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Sample records for reducing plasmodium falciparum-infected

  1. The Dynamics of Natural Plasmodium falciparum Infections

    PubMed Central

    Felger, Ingrid; Maire, Martin; Bretscher, Michael T.; Falk, Nicole; Tiaden, André; Sama, Wilson; Beck, Hans-Peter; Owusu-Agyei, Seth; Smith, Thomas A.

    2012-01-01

    Background Natural immunity to Plasmodium falciparum has been widely studied, but its effects on parasite dynamics are poorly understood. Acquisition and clearance rates of untreated infections are key elements of the dynamics of malaria, but estimating these parameters is challenging because of frequent super-infection and imperfect detectability of parasites. Consequently, information on effects of host immune status or age on infection dynamics is fragmentary. Methods An age-stratified cohort of 347 individuals from Northern Ghana was sampled six times at 2 month intervals. High-throughput capillary electrophoresis was used to genotype the msp-2 locus of all P. falciparum infections detected by PCR. Force of infection (FOI) and duration were estimated for each age group using an immigration-death model that allows for imperfect detection of circulating parasites. Results Allowing for imperfect detection substantially increased estimates of FOI and duration. Effects of naturally acquired immunity on the FOI and duration would be reflected in age dependence in these indices, but in our cohort data FOI tended to increase with age in children. Persistence of individual parasite clones was characteristic of all age-groups. Duration peaked in 5–9 year old children (average duration 319 days, 95% confidence interval 318;320). Conclusions The main age-dependence is on parasite densities, with only small age-variations in the FOI and persistence of infections. This supports the hypothesis that acquired immunity controls transmission mainly by limiting blood-stage parasite densities rather than changing rates of acquisition or clearance of infections. PMID:23029082

  2. Peripheral Blood Cell Signatures of Plasmodium falciparum Infection during Pregnancy

    PubMed Central

    Ibitokou, Samad; Oesterholt, Mayke; Brutus, Laurent; Borgella, Sophie; Agbowaï, Carine; Ezinmègnon, Sèm; Lusingu, John; Schmiegelow, Christentze; Massougbodji, Achille; Deloron, Philippe; Troye-Blomberg, Marita; Varani, Stefania; Luty, Adrian J. F.; Fievet, Nadine

    2012-01-01

    Sequestration of Plasmodium falciparum-infected erythrocytes in placental intervillous spaces causes inflammation and pathology. Knowledge of the profiles of immune cells associated with the physiopathology of pregnancy-associated malaria (PAM) is scarce. We conducted a longitudinal, prospective study, both in Benin and Tanzania, including ∼1000 pregnant women in each site with systematic follow-up at scheduled antenatal visits until delivery. We used ex vivo flow cytometry to identify peripheral blood mononuclear cell (PBMC) profiles that are associated with PAM and anaemia, determining the phenotypic composition and activation status of PBMC in selected sub-groups with and without PAM both at inclusion and at delivery in a total of 302 women. Both at inclusion and at delivery PAM was associated with significantly increased frequencies both of B cells overall and of activated B cells. Infection-related profiles were otherwise quite distinct at the two different time-points. At inclusion, PAM was associated with anaemia, with an increased frequency of immature monocytes and with a decreased frequency of regulatory T cells (Treg). At delivery, infected women presented with significantly fewer plasmacytoid dendritic cells (DC), more myeloid DC expressing low levels of HLA-DR, and more effector T cells (Teff) compared to uninfected women. Independent associations with an increased risk of anaemia were found for altered antigen-presenting cell frequencies at inclusion, but for an increased frequency of Teff at delivery. Our findings emphasize the prominent role played by B cells during PAM whenever it arises during pregnancy, whilst also revealing signature changes in other circulating cell types that, we conclude, primarily reflect the relative duration of the infections. Thus, the acute, recently-acquired infections present at delivery were marked by changes in DC and Teff frequencies, contrasting with infections at inclusion, considered chronic in nature, that

  3. MicroRNA-regulation of Anopheles gambiae immunity to Plasmodium falciparum infection and midgut microbiota.

    PubMed

    Dennison, Nathan J; BenMarzouk-Hidalgo, Omar J; Dimopoulos, George

    2015-03-01

    Invasion of the malaria vector Anopheles gambiae midgut by Plasmodium parasites triggers transcriptional changes of immune genes that mediate the antiparasitic defense. This response is largely regulated by the Toll and Immune deficiency (IMD) pathways. To determine whether A. gambiae microRNAs (miRNAs) are involved in regulating the anti-Plasmodium defense, we showed that suppression of miRNA biogenesis results in increased resistance to Plasmodium falciparum infection. In silico analysis of A. gambiae immune effector genes identified multiple transcripts with miRNA binding sites. A comparative miRNA microarray abundance analysis of P. falciparum infected and naïve mosquito midgut tissues showed elevated abundance of miRNAs aga-miR-989 and aga-miR-305 in infected midguts. Antagomir inhibition of aga-miR-305 increased resistance to P. falciparum infection and suppressed the midgut microbiota. Conversely, treatment of mosquitoes with an artificial aga-miR-305 mimic increased susceptibility to P. falciparum infection and resulted in expansion of midgut microbiota, suggesting that aga-miR-305 acts as a P. falciparum and gut microbiota agonist by negatively regulating the mosquito immune response. In silico prediction of aga-miR-305 target genes identified several anti-Plasmodium effectors. Our study shows that A. gambiae aga-miR-305 regulates the anti-Plasmodium response and midgut microbiota, likely through post-transcriptional modification of immune effector genes.

  4. Failure to block adhesion of Plasmodium falciparum-infected erythrocytes to ICAM-1 with soluble ICAM-1.

    PubMed Central

    Craig, A G; Pinches, R; Khan, S; Roberts, D J; Turner, G D; Newbold, C I; Berendt, A R

    1997-01-01

    The adhesion of Plasmodium falciparum-infected erythrocytes is thought to play a central role in the pathogenesis of severe malaria. ICAM-1 has been identified as one of the host receptors for parasitized erythrocytes and has been implicated as being involved in progression to cerebral malaria. Thus, intervention strategies based on the reversal of this interaction could potentially be used to reduce morbidity and mortality. We have investigated the inhibition of the interaction between ICAM-1 and infected erythrocytes by using recombinant soluble ICAM-1 as competitor and find that we are unable to reduce adhesion to ICAM-1 in vitro. PMID:9353036

  5. Severe Plasmodium falciparum infection mimicking acute myocardial infarction.

    PubMed

    Sulaiman, Helmi; Ismail, Muhammad Dzafir; Jalalonmuhali, Maisarah; Atiya, Nadia; Ponnampalavanar, Sasheela

    2014-08-30

    This case report describes a case of presumed acute myocardial infarction in a returned traveler who was later diagnosed to have severe malaria. Emergency coronary angiography was normal and subsequent peripheral blood film was positive for Plasmodium falciparum.

  6. Prevalence and risk factors of Plasmodium falciparum infections in pregnant women of Luanda, Angola.

    PubMed

    Valente, Bianor; Campos, Paulo A; do Rosário, Virgílio E; Varandas, Luis; Silveira, Henrique

    2011-10-01

    Pregnant women are at increased risk of malaria, but in Angola, epidemiologic data from this group is almost inexistent. We conducted a cross-sectional study to determine the prevalence and risk factors of Plasmodium falciparum infections in 567 pregnant Angolan women living in Luanda province. One in five women had P. falciparum at delivery, diagnosed by PCR assay. Age, residence and history of malaria during pregnancy were significantly associated with P. falciparum infection, but gravidity and use of anti-malarial drugs were not. Placental infections were significantly more common in women ≤18 years old and in primigravidae, but we could not correlate placental infections with poor pregnancy outcomes. These findings are relevant to malaria control policies in Luanda, Angola.

  7. Type I Interferons Regulate Immune Responses in Humans with Blood-Stage Plasmodium falciparum Infection

    PubMed Central

    Montes de Oca, Marcela; Kumar, Rajiv; de Labastida Rivera, Fabian; Amante, Fiona H.; Sheel, Meru; Faleiro, Rebecca J.; Bunn, Patrick T.; Best, Shannon E.; Beattie, Lynette; Ng, Susanna S.; Edwards, Chelsea L.; Boyle, Glen M.; Price, Ric N.; Anstey, Nicholas M.; Loughland, Jessica R.; Burel, Julie; Doolan, Denise L.; Haque, Ashraful; McCarthy, James S.; Engwerda, Christian R.

    2016-01-01

    Summary The development of immunoregulatory networks is important to prevent disease. However, these same networks allow pathogens to persist and reduce vaccine efficacy. Here, we identify type I interferons (IFNs) as important regulators in developing anti-parasitic immunity in healthy volunteers infected for the first time with Plasmodium falciparum. Type I IFNs suppressed innate immune cell function and parasitic-specific CD4+ T cell IFNγ production, and they promoted the development of parasitic-specific IL-10-producing Th1 (Tr1) cells. Type I IFN-dependent, parasite-specific IL-10 production was also observed in P. falciparum malaria patients in the field following chemoprophylaxis. Parasite-induced IL-10 suppressed inflammatory cytokine production, and IL-10 levels after drug treatment were positively associated with parasite burdens before anti-parasitic drug administration. These findings have important implications for understanding the development of host immune responses following blood-stage P. falciparum infection, and they identify type I IFNs and related signaling pathways as potential targets for therapies or vaccine efficacy improvement. PMID:27705789

  8. Theoretical models for near forward light scattering by a Plasmodium falciparum infected red blood cell

    NASA Astrophysics Data System (ADS)

    Sharma, S. K.

    2012-12-01

    A number of experimental elastic light scattering studies have been performed in the past few years with the aim of developing automated in vivo tools for differentiating a healthy red blood cell from a Plasmodium falciparum infected cell. This paper examines some theoretical aspects of the problem. An attempt has been made to simulate the scattering patterns of healthy as well as infected individual red blood cells. Two models, namely, a homogeneous sphere model and a coated sphere model have been considered. The scattering patterns predicted by these models are examined. A possible method for discriminating infected red blood cells from healthy ones has been suggested.

  9. Analysis of Breath Specimens for Biomarkers of Plasmodium falciparum Infection

    PubMed Central

    Berna, Amalia Z.; McCarthy, James S.; Wang, Rosalind X.; Saliba, Kevin J.; Bravo, Florence G.; Cassells, Julie; Padovan, Benjamin; Trowell, Stephen C.

    2015-01-01

    Currently, the majority of diagnoses of malaria rely on a combination of the patient's clinical presentation and the visualization of parasites on a stained blood film. Breath offers an attractive alternative to blood as the basis for simple, noninvasive diagnosis of infectious diseases. In this study, breath samples were collected from individuals during controlled malaria to determine whether specific malaria-associated volatiles could be detected in breath. We identified 9 compounds whose concentrations varied significantly over the course of malaria: carbon dioxide, isoprene, acetone, benzene, cyclohexanone, and 4 thioethers. The latter group, consisting of allyl methyl sulfide, 1-methylthio-propane, (Z)-1-methylthio-1-propene, and (E)-1-methylthio-1-propene, had not previously been associated with any disease or condition. Before the availability of antimalarial drug treatment, there was evidence of concurrent 48-hour cyclical changes in the levels of both thioethers and parasitemia. When thioether concentrations were subjected to a phase shift of 24 hours, a direct correlation between the parasitemia and volatile levels was revealed. Volatile levels declined monotonically approximately 6.5 hours after initial drug treatment, correlating with clearance of parasitemia. No thioethers were detected in in vitro cultures of Plasmodium falciparum. The metabolic origin of the thioethers is not known, but results suggest that interplay between host and parasite metabolic pathways is involved in the production of these thioethers. PMID:25810441

  10. Molecular Aspects of Plasmodium falciparum Infection during Pregnancy

    PubMed Central

    Ndam, Nicaise Tuikue; Deloron, Philippe

    2007-01-01

    Cytoadherence of Plasmodium-falciparum-parasitized red blood cells (PRBCs) to host receptors is the key phenomenon in the pathological process of the malaria disease. Some of these interactions can originate poor outcomes responsible for 1 to 3 million annual deaths mostly occurring among children in sub-Saharan Africa. Pregnancy-associated malaria (PAM) represents an important exception of the disease occurring at adulthood in malaria endemic settings. Consequences of this are shared between the mother (maternal anemia) and the baby (low birth weight and infant mortality). Demonstrating that parasites causing PAM express specific variant surface antigens (VSAPAM), including the P. falciparum erythrocyte membrane protein 1 (P f EMP1) variant VAR2CSA, that are targets for protective immunity has strengthened the possibility for the development of PAM-specific vaccine. In this paper, we review the molecular basis of malaria pathogenesis attributable to the erythrocyte stages of the parasites, and findings supporting potential anti-PAM vaccine components evidenced in PAM. PMID:17641725

  11. Marked Rise in the Prevalence of Asymptomatic Plasmodium falciparum Infection in Rural Gabon

    PubMed Central

    Pegha Moukandja, Irène; Biteghe Bi Essone, Jean Claude; Sagara, Issaka; Kassa Kassa, Roland Fabrice; Ondzaga, Julien; Lékana Douki, Jean-Bernard; Bouyou Akotet, Marielle; Nkoghe Mba, Dieudonne; Touré Ndouo, Fousseyni S.

    2016-01-01

    Control strategies implemented a decade ago led to a marked reduction in the prevalence of malaria in many countries. In Dienga, southeastern Gabon, the prevalence of microscopic P. falciparum infection was 7% in 2003, close to the pre-elimination threshold of 5%. The aim of this work was to determine the prevalence of P. falciparum infection in the same community a decade later. A cohort of 370 individuals aged from 3 to 85 years living in Dienga was investigated for P. falciparum infection; during six passages (P) in 15-month period. Demographic data were collected, along with behaviors and attitudes towards malaria. Plasmodium infection was diagnosed by microscopy (ME), followed by PCR to detect submicroscopic infection. The prevalence of P. falciparum infection in P1, P2, P3, P4, P5 and P6 was respectively 43.5% (25.1% ME+, 18.4% PCR+); 40.9% (27.0% ME+, 13.9% PCR+), 52.7% (26.1% ME+, 26.6% PCR+); 34.1% (14.1% ME+, 20% PCR+), 57.7% (25.4.% ME+, 32.3% PCR+); and 46.2% (21.4% ME+, 24.8% PCR+) with an overall average of 45.9% (95%CI [37.0–54.7], 23.2% ME+ and 22.7% PCR+). P4 and P5 prevalences were statically different throughout the six passages. Microscopic prevalence was significantly higher than that observed ten years ago (23% [n = 370] vs 7% [n = 323], p < 0.001). Asymptomatic infections were the most frequent (96%). Gametocytes were detected in levels ranging from 5.9% to 13.9%. Insecticide-treated nets, indoor residual insecticides, and self-medication were used by respectively 33.2% (95%CI [29.0–37.4]), 17.7% (95%CI [15.5–19.9]) and 12.1% (95%CI [10.6–13.6]) of the study population. A near-threefold increase in P. falciparum infection has been observed in a rural area of southeastern Gabon during a 10-year period. Most infections were asymptomatic, but these subjects likely represent a parasite reservoir. These findings call for urgent reinforcement of preventive measures. PMID:27228058

  12. Marked Rise in the Prevalence of Asymptomatic Plasmodium falciparum Infection in Rural Gabon.

    PubMed

    Pegha Moukandja, Irène; Biteghe Bi Essone, Jean Claude; Sagara, Issaka; Kassa Kassa, Roland Fabrice; Ondzaga, Julien; Lékana Douki, Jean-Bernard; Bouyou Akotet, Marielle; Nkoghe Mba, Dieudonne; Touré Ndouo, Fousseyni S

    2016-01-01

    Control strategies implemented a decade ago led to a marked reduction in the prevalence of malaria in many countries. In Dienga, southeastern Gabon, the prevalence of microscopic P. falciparum infection was 7% in 2003, close to the pre-elimination threshold of 5%. The aim of this work was to determine the prevalence of P. falciparum infection in the same community a decade later. A cohort of 370 individuals aged from 3 to 85 years living in Dienga was investigated for P. falciparum infection; during six passages (P) in 15-month period. Demographic data were collected, along with behaviors and attitudes towards malaria. Plasmodium infection was diagnosed by microscopy (ME), followed by PCR to detect submicroscopic infection. The prevalence of P. falciparum infection in P1, P2, P3, P4, P5 and P6 was respectively 43.5% (25.1% ME+, 18.4% PCR+); 40.9% (27.0% ME+, 13.9% PCR+), 52.7% (26.1% ME+, 26.6% PCR+); 34.1% (14.1% ME+, 20% PCR+), 57.7% (25.4.% ME+, 32.3% PCR+); and 46.2% (21.4% ME+, 24.8% PCR+) with an overall average of 45.9% (95%CI [37.0-54.7], 23.2% ME+ and 22.7% PCR+). P4 and P5 prevalences were statically different throughout the six passages. Microscopic prevalence was significantly higher than that observed ten years ago (23% [n = 370] vs 7% [n = 323], p < 0.001). Asymptomatic infections were the most frequent (96%). Gametocytes were detected in levels ranging from 5.9% to 13.9%. Insecticide-treated nets, indoor residual insecticides, and self-medication were used by respectively 33.2% (95%CI [29.0-37.4]), 17.7% (95%CI [15.5-19.9]) and 12.1% (95%CI [10.6-13.6]) of the study population. A near-threefold increase in P. falciparum infection has been observed in a rural area of southeastern Gabon during a 10-year period. Most infections were asymptomatic, but these subjects likely represent a parasite reservoir. These findings call for urgent reinforcement of preventive measures. PMID:27228058

  13. J-dot targeting of an exported HSP40 in Plasmodium falciparum-infected erythrocytes.

    PubMed

    Petersen, Wiebke; Külzer, Simone; Engels, Sonja; Zhang, Qi; Ingmundson, Alyssa; Rug, Melanie; Maier, Alexander G; Przyborski, Jude M

    2016-07-01

    Plasmodium falciparum exports a large number of proteins to its host cell, the mature human erythrocyte, where they are involved in host cell modification. Amongst the proteins trafficked to the host cell, many are heat shock protein (HSP)40 homologues. We previously demonstrated that at least two exported PfHSP40s (referred to as PFE55 and PFA660) localise to mobile structures in the P. falciparum-infected erythrocyte (Kulzer et al., 2010), termed J-dots. The complete molecular content of these structures has not yet been completely resolved, however it is known that they also contain an exported HSP70, PfHSP70x, and are potentially involved in transport of the major cytoadherance ligand, PfEMP1, through the host cell. To understand more about the nature of the association of exported HSP40s with J-dots, here we have studied the signal requirements for recruitment of the proteins to these structures. By expressing various exported GFP chimeras, we can demonstrate that the predicted substrate binding domain is necessary and sufficient for J-dot targeting. This targeting only occurs in human erythrocytes infected with P. falciparum, as it is not conserved when expressing a P. falciparum HSP40 in Plasmodium berghei-infected murine red blood cells, suggesting that J-dots are P. falciparum-specific. This data reveals a new mechanism for targeting of exported proteins to intracellular structures in the P. falciparum-infected erythrocyte.

  14. Subtle changes in Plasmodium falciparum infection complexity following enhanced intervention in Malawi.

    PubMed

    Sisya, Tamika J; Kamn'gona, Raphael M; Vareta, Jimmy A; Fulakeza, Joseph M; Mukaka, Mavuto F J; Seydel, Karl B; Laufer, Miriam K; Taylor, Terrie E; Nkhoma, Standwell C

    2015-02-01

    With support from the Global Fund, the United States President's Malaria Initiative (PMI) and other cooperating partners, Malawi is implementing a comprehensive malaria control programme involving indoor residual spraying in targeted districts, universal coverage with insecticide-treated bed nets, use of rapid diagnostic tests to confirm the clinical diagnosis of malaria and use of the highly effective artemisinin-based combination therapy, artemether-lumefantrine (AL), as the first-line treatment for malaria. We genotyped 24 genome-wide single nucleotide polymorphisms (SNPs) in Plasmodium falciparum infections (n=316) sampled from a single location in Malawi before (2006 and 2007) and after enhanced intervention (2008 and 2012). The SNP data generated were used to examine temporal changes in the proportion of multiple-genotype infections (MIs), mean number of heterozygous SNPs within MIs, parasite genetic diversity (expected heterozygosity and genotypic richness), multilocus linkage disequilibrium and effective population size (N(e)). While the proportion of MIs, expected heterozygosity, genotypic richness, multilocus linkage disequilibrium and Ne were unchanged over time, the mean number (±standard deviation) of heterozygous SNPs within MIs decreased significantly (p=0.01) from 9(±1) in 2006 to 7(±1) in 2012. These findings indicate that the genetic diversity of P. falciparum malaria parasites in this area remains high, suggesting that only subtle gains, if any, have been made in reducing malaria transmission. Continued surveillance is required to evaluate the impact of malaria control interventions in this area and the rest of Malawi, and to better target control interventions.

  15. Prevalence and transmission pattern of Plasmodium falciparum infection in Osogbo metropolis, southwest, Nigeria.

    PubMed

    Ogungbamigbe, T O; Ojurongbe, O O; Ogunro, P S; Olowe, O A; Elemile, P O

    2007-12-01

    Plasmodium falciparum malaria is an endemic disease especially in tropical areas with heavy rainfall that spread round the year. We therefore sought to investigate the prevalence pattern and clinical presentation of falciparum malaria in Oso degrees c were assessed and screened for plasmodium falciparum infection by clinical assessment and microscopy using both thick and thin blood smears over a period of 12 months- August 2004 and July 2005. The prevalence of Plasmodium falciparum infection was found to be 52.8% with 341/646 of the patients been positive for Plasmodium falciparum parasite based on microscopy. Three hundred and five (47.2%) were aparasitaemic of which 162 (25.1%) had bronchopneumonia, 99 (15.3%) had upper respiratory tract infection, 32 (5.0%) had gastroenteritis and 12 (1.9%) had Otitis media. Between August and November 2004, 250 patients were screened and 160 (57.6%) of these patients were positive, while 180 patients were screened between December 2004 and March 2005 and 51 (28.3%) were positive. Between April 2005 and July 2005, 216 patients were screened and 130 (60.2%) of the patients were positive. When compared, the differences in the percentage of patients with positive microscopy in December to March with April to July and August to November were found to be significant (P < 0.0001), whereas the percentage difference in patients with positive microscopy in August to November and April to July was not significant (P = 0.442). The result of this study clearly shows that there are two distinct peaks of malaria transmission pattern in consonance with the rainfall pattern in the area. PMID:18564645

  16. Circulating concentrations of soluble granzyme A and B increase during natural and experimental Plasmodium falciparum infections.

    PubMed

    Hermsen, C C; Konijnenberg, Y; Mulder, L; Loé, C; van Deuren, M; van der Meer, J W M; van Mierlo, G J; Eling, W M C; Hack, C E; Sauerwein, R W

    2003-06-01

    Release of soluble Granzymes (sGranzymes) is considered to reflect activation of cytotoxic T lymphocytes and NK cells. sGranzymes and a number of pro-inflammatory cytokines were measured in plasma of malaria patients with natural or experimentally induced Plasmodium falciparum infections. Concentrations of sGranzyme A and B, IL-10, IL-12p70 and CRP were significantly increased in African children presenting with clinical malaria; IL-10 and CRP concentrations were significantly correlated with disease severity. In nonimmune Dutch volunteers which were experimentally infected by P. falciparum-infected mosquitoes, sGranzyme A increment started 1-2 days prior to clinical symptoms and microscopically detectable parasitaemia. This coincided with increases in IFNgamma, IL-12p40 and IL-8, while sGranzyme B and IL-10 levels increased 24-48 h later. The elevation of sGranzyme A and IFNgamma in nonimmune volunteers suggests that NK cells are activated upon release of parasites by infected liver cells and subsequently during blood stage infection; thus, NK cells are likely involved innate immune human host resistance in the early phase of a malaria infection.

  17. Interferon regulatory factor-1 polymorphisms are associated with the control of Plasmodium falciparum infection

    PubMed Central

    Mangano, Valentina D; Luoni, Gaia; Rockett, Kirk A; Sirima, Bienvenu S; Konaté, Amadou; Forton, Julian; Clark, Taane; Bancone, Germana; Akha, Elham Sadighi; Kwiatkowski, Dominic P; Modiano, David

    2010-01-01

    We describe the haplotypic structure of the Interferon Regulatory Factor-1 (IRF-1) locus in two West African ethnic groups, Fulani and Mossi, that differ in their susceptibility and immune response to Plasmodium falciparum malaria. Both populations showed significant associations between IRF-1 polymorphisms and carriage of P. falciparum infection, with different patterns of association that may reflect their different haplotypic architecture. Genetic variation at this locus does not therefore account for the Fulani-specific resistance to malaria while it could contribute to parasite clearance's ability in populations living in endemic areas. We then conducted a case-control study of three haplotype-tagging Single Nucleotide Polymorphisms (htSNPs) in 370 hospitalized malaria patients (160 severe and 210 uncomplicated) and 410 healthy population controls, all from the Mossi ethnic group. All 3 htSNPs showed correlation with blood infection levels in malaria patients, and the rs10065633 polymorphism was associated with severe disease (p=0.02). These findings provide the first evidence of the involvement in malaria susceptibility of a specific locus within the 5q31 region, previously shown to be linked with P. falciparum infection levels. PMID:18200030

  18. Plasmodium falciparum infection rates for some Anopheles spp. from Guinea-Bissau, West Africa

    PubMed Central

    Sanford, Michelle R.; Cornel, Anthony J.; Nieman, Catelyn C.; Dinis, Joao; Marsden, Clare D.; Weakley, Allison M.; Han, Sarah; Rodrigues, Amabelia; Lanzaro, Gregory C.; Lee, Yoosook

    2014-01-01

    Presence of Plasmodium falciparum circumsporozoite protein (CSP) was detected by enzyme linked immunosorbent assay (ELISA) in a sample of Anopheles gambiae s.s., A. melas and A. pharoensis collected in Guinea-Bissau during October and November 2009. The percentage of P. falciparum infected samples (10.2% overall; confidence interval (CI): 7.45-13.6%) was comparable to earlier studies from other sites in Guinea-Bissau (9.6-12.4%). The majority of the specimens collected were identified as A. gambiae which had an individual infection rate of 12.6 % (CI: 8.88-17.6) across collection sites. A small number of specimens of A. coluzzii, A. coluzzii x A. gambiae hybrids, A. melas and A. pharoensis were collected and had infection rates of 4.3% (CI:0.98-12.4), 4.1% (CI:0.35-14.5), 11.1% (CI:1.86-34.1) and 33.3% (CI:9.25-70.4) respectively. Despite being present in low numbers in indoor collections, the exophilic feeding behaviors of A. melas (N=18) and A. pharoensis (N=6) and high infection rates observed in this survey suggest falciparum-malaria transmission potential outside of the protection of bed nets. PMID:25383188

  19. A microfluidic system to study cytoadhesion of Plasmodium falciparum infected erythrocytes to primary brain microvascularendothelial cells.

    PubMed

    Herricks, Thurston; Seydel, Karl B; Turner, George; Molyneux, Malcolm; Heyderman, Robert; Taylor, Terrie; Rathod, Pradipsinh K

    2011-09-01

    The cellular events leading to severe and complicated malaria in some Plasmodium falciparum infections are poorly understood. Additional tools are required to better understand the pathogenesis of this disease. In this technical report, we describe a microfluidic culture system and image processing algorithms that were developed to observe cytoadhesion interactions of P. falciparum parasitized erythrocytes rolling on primary brain microvascularendothelial cells. We isolated and cultured human primary microvascular brain endothelial cells in a closed loop microfluidic culture system where a peristaltic pump and media reservoirs were integrated onto a microscope stage insert. We developed image processing methods to enhance contrast of rolling parasitized erythrocytes on endothelial cells and to estimate the local wall shear stress. The velocity of parasitized erythrocytes rolling on primary brain microvascularendothelial cells was then measured under physiologically relevant wall shear stresses. Finally, we deployed this method successfully at a field site in Blantyre, Malawi. The method is a promising new tool for the investigation of the pathogenesis of severe malaria.

  20. De Novo Generated Human Red Blood Cells in Humanized Mice Support Plasmodium falciparum Infection.

    PubMed

    Amaladoss, Anburaj; Chen, Qingfeng; Liu, Min; Dummler, Sara K; Dao, Ming; Suresh, Subra; Chen, Jianzhu; Preiser, Peter R

    2015-01-01

    Immunodeficient mouse-human chimeras provide a powerful approach to study host specific pathogens like Plasmodium (P.) falciparum that causes human malaria. Existing mouse models of P. falciparum infection require repeated injections of human red blood cells (RBCs). In addition, clodronate lipsomes and anti-neutrophil antibodies are injected to suppress the clearance of human RBCs by the residual immune system of the immunodeficient mice. Engraftment of NOD-scid Il2rg-/- mice with human hematopoietic stem cells leads to reconstitution of human immune cells. Although human B cell reconstitution is robust and T cell reconstitution is reasonable in the recipient mice, human RBC reconstitution is generally poor or undetectable. The poor reconstitution is mainly the result of a deficiency of appropriate human cytokines that are necessary for the development and maintenance of these cell lineages. Delivery of plasmid DNA encoding human erythropoietin and interleukin-3 into humanized mice by hydrodynamic tail-vein injection resulted in significantly enhanced reconstitution of erythrocytes. With this improved humanized mouse, here we show that P. falciparum infects de novo generated human RBCs, develops into schizonts and causes successive reinvasion. We also show that different parasite strains exhibit variation in their ability to infect these humanized mice. Parasites could be detected by nested PCR in the blood samples of humanized mice infected with P. falciparum K1 and HB3 strains for 3 cycles, whereas in other strains such as 3D7, DD2, 7G8, FCR3 and W2mef parasites could only be detected for 1 cycle. In vivo adaptation of K1 strain further improves the infection efficiency and parasites can be detected by microscopy for 3 cycles. The parasitemia ranges between 0.13 and 0.25% at the first cycle of infection, falls between 0.08 and 0.15% at the second cycle, and drops to barely detectable levels at the third cycle of infection. Compared to existing mouse models, our

  1. Adverse Pregnancy Outcomes in an Area Where Multidrug-Resistant Plasmodium vivax and Plasmodium falciparum Infections Are Endemic

    PubMed Central

    Poespoprodjo, Jeanne Rini; Fobia, Wendy; Kenangalem, Enny; Lampah, Daniel A.; Warikar, Noah; Seal, Andrew; McGready, Rose; Sugiarto, Paulus; Tjitra, Emiliana; Anstey, Nicholas M.; Price, Ric N.

    2009-01-01

    Background Plasmodium falciparum infection exerts a considerable burden on pregnant women, but less is known about the adverse consequences of Plasmodium vivax infection. Methods In Papua, Indonesia, where multiple drug resistance to both species has emerged, we conducted a cross-sectional hospital-based study to quantify the risks and consequences of maternal malaria. Results From April 2004 through December 2006, 3046 pregnant women were enrolled in the study. The prevalence of parasitemia at delivery was 16.8% (432 of 2570 women had infections), with 152 (35.2%) of these 432 infections being associated with fever. The majority of infections were attributable to P. falciparum (250 [57.9%]); 146 (33.8%) of the infections were attributable to P. vivax, and 36 (8.3%) were coinfections with both species. At delivery, P. falciparum infection was associated with severe anemia (hemoglobin concentration, <7 g/dL; odds ratio [OR], 2.8; 95% confidence interval [95% CI], 2.0–4.0) and a 192 g (95% CI, 119–265) reduction in mean birth weight (P < .001). P. vivax infection was associated with an increased risk of moderate anemia (hemoglobin concentration, 7–11 g/dL; OR, 1.8; 95% CI, 1.2–2.9; P = .01) and a 108 g (95% CI, 17.5–199) reduction in mean birth weight (P < .019). Parasitemia was associated with preterm delivery (OR, 1.5; 95% CI, 1.1–2.0; P = .02) and stillbirth (OR, 2.3; 95% CI, 1.3–4.1; P = .007) but was not associated with these outcomes after controlling for the presence of fever and severe anemia, suggesting that malaria increases the risk of preterm delivery and stillbirth through fever and contribution to severe anemia rather than through parasitemia per se. Conclusions These observations highlight the need for novel, safe, and effective treatment and prevention strategies against both multidrug-resistant P. falciparum and multidrug-resistant P. vivax infections in pregnant women in areas of mixed endemicity. PMID:18419439

  2. Febrile temperatures induce cytoadherence of ring-stage Plasmodium falciparum-infected erythrocytes.

    PubMed

    Udomsangpetch, Rachanee; Pipitaporn, Busaba; Silamut, Kamolrat; Pinches, Robert; Kyes, Sue; Looareesuwan, Sornchai; Newbold, Christopher; White, Nicholas J

    2002-09-01

    In falciparum malaria, the malaria parasite induces changes at the infected red blood cell surface that lead to adherence to vascular endothelium and other red blood cells. As a result, the more mature stages of Plasmodium falciparum are sequestered in the microvasculature and cause vital organ dysfunction, whereas the ring stages circulate in the blood stream. Malaria is characterized by fever. We have studied the effect of febrile temperatures on the cytoadherence in vitro of P. falciparum-infected erythrocytes. Freshly obtained ring-stage-infected red blood cells from 10 patients with acute falciparum malaria did not adhere to the principle vascular adherence receptors CD36 or intercellular adhesion molecule-1 (ICAM-1). However, after a brief period of heating to 40 degrees C, all ring-infected red blood cells adhered to CD36, and some isolates adhered to ICAM-1, whereas controls incubated at 37 degrees C did not. Heating to 40 degrees C accelerated cytoadherence and doubled the maximum cytoadherence observed (P < 0.01). Erythrocytes infected by ring-stages of the ICAM-1 binding clone A4var also did not cytoadhere at 37 degrees C, but after heating to febrile temperatures bound to both CD36 and ICAM-1. Adherence of red blood cells infected with trophozoites was also increased considerably by brief heating. The factor responsible for heat induced adherence was shown to be the parasite derived variant surface protein PfEMP-1. RNA analysis showed that levels of var mRNA did not differ between heated and unheated ring-stage parasites. Thus fever-induced adherence appeared to involve increased trafficking of PfEMP-1 to the erythrocyte membrane. Fever induced cytoadherence is likely to have important pathological consequences and may explain both clinical deterioration with fever in severe malaria and the effects of antipyretics on parasite clearance. PMID:12177447

  3. Cells and mediators of inflammation (C-reactive protein, nitric oxide, platelets and neutrophils) in the acute and convalescent phases of uncomplicated Plasmodium vivax and Plasmodium falciparum infection.

    PubMed

    Lima-Junior, Josué da Costa; Rodrigues-da-Silva, Rodrigo Nunes; Pereira, Virgínia Araújo; Storer, Fábio Luiz; Perce-da-Silva, Daiana de Souza; Fabrino, Daniela Leite; Santos, Fátima; Banic, Dalma Maria; Oliveira-Ferreira, Joseli de

    2012-12-01

    The haematological changes and release of soluble mediators, particularly C-reactive protein (CRP) and nitric oxide (NO), during uncomplicated malaria have not been well studied, especially in Brazilian areas in which the disease is endemic. Therefore, the present study examined these factors in acute (day 0) and convalescent phase (day 15) patients infected with Plasmodium falciparum and Plasmodium vivax malaria in the Brazilian Amazon. Haematologic parameters were measured using automated cell counting, CRP levels were measured with ELISA and NO plasma levels were measured by the Griess reaction. Our data indicate that individuals with uncomplicated P. vivax and P. falciparum infection presented similar inflammatory profiles with respect to white blood cells, with high band cell production and a considerable degree of thrombocytopaenia during the acute phase of infection. Higher CRP levels were detected in acute P. vivax infection than in acute P. falciparum infection, while higher NO was detected in patients with acute and convalescent P. falciparum infections. Although changes in these mediators cannot predict malaria infection, the haematological aspects associated with malaria infection, especially the roles of platelets and band cells, need to be investigated further.

  4. Detection and cartography of the fluorinated antimalarial drug mefloquine in normal and Plasmodium falciparum infected red blood cells by scanning ion microscopy and mass spectrometry.

    PubMed

    Adovelande, J; Boulard, Y; Berry, J P; Galle, P; Slodzian, G; Schrével, J

    1994-01-01

    Due to the presence of fluorine atoms in its molecule, the antimalarial drug mefloquine (MQ) can be easily detected in normal and Plasmodium falciparum infected red blood cells (RBC) by scanning ion microscopy and mass spectrometry. The P falciparum infected RBC exhibited intense distribution of MQ inside the parasite. The main compartments of the parasite which accumulate the drug were the food vacuole and the cytoplasm. The correlation between fluorine (19F-) and phosphorus (31P-) as well as probes for the DNA synthesis (BrdU and IdU) emissions shows that the parasite nucleus is also accessible to the drug. This study demonstrates that SIMS technique on smear preparations is an efficient approach for the direct detection and cartography of fluorinated antimalarial drugs in normal and P falciparum infected RBC, without radioactive labelling.

  5. The Practice of Jhum Cultivation and Its Relationship to Plasmodium falciparum Infection in the Chittagong Hill Districts of Bangladesh

    PubMed Central

    Galagan, Sean R.; Prue, Chai Shwai; Khyang, Jacob; Khan, Wasif Ali; Ahmed, Sabeena; Ram, Malathi; Alam, Mohammad Shafiul; Haq, M. Zahirul; Akter, Jasmin; Streatfield, Peter Kim; Glass, Gregory; Norris, Douglas E.; Nyunt, Myaing Myaing; Shields, Timothy; Sullivan, David J.; Sack, David A.

    2014-01-01

    Malaria is endemic in the Chittagong Hill Districts of southeastern Bangladesh. Previous epidemiological analyses identified the agricultural practice of jhum cultivation as a potential risk factor for malaria infection. We conducted qualitative interviews with jhum cultivators and surveillance workers to describe jhum cultivation and used demographic and malaria surveillance in two study unions from May of 2010 to August of 2012 to better understand the relationship between jhum cultivation and malaria infection. Qualitative interviews revealed that jhum cultivation is conducted on remote, steep hillsides by ethnic tribal groups. Quantitative analyses found that adult jhum cultivators and individuals who live in the same residence had significantly higher incidence rates of symptomatic Plasmodium falciparum infection compared with non-cultivators. These results confirm that jhum cultivation is an independent risk factor for malaria infection and underscore the need for malaria testing and treatment services to reach remote populations in the Chittagong Hill Districts. PMID:24821843

  6. Parasitic co-infections: does Ascaris lumbricoides protect against Plasmodium falciparum infection?

    PubMed

    Brutus, Laurent; Watier, Laurence; Briand, Valérie; Hanitrasoamampionona, Virginie; Razanatsoarilala, Hélène; Cot, Michel

    2006-08-01

    A controlled randomized trial of antihelminthic treatment was undertaken in 1996-1997 in a rural area of Madagascar where populations were simultaneously infected with Ascaris lumbricoides and Plasmodium falciparum. Levamisole was administered bimonthly to 164 subjects, randomized on a family basis, whereas 186 were controls. While levamisole proved to be highly effective in reducing Ascaris egg loads in the treated group (P < 10(-3) at all bimonthly visits), subjects more than 5 years of age, treated with levamisole had a significant increase in their P. falciparum densities compared with controls (P = 0.02), whereas there was no effect of anti-helminthic treatment on children 6 months to 4 years of age. The demonstration of a clear negative interaction between Ascaris infection and malaria parasite density has important implications. Single community therapy programs to deliver treatments against several parasitic infections could avoid an increase of malaria attacks after mass treatment of ascariasis.

  7. Impact of trehalose transporter knockdown on Anopheles gambiae stress adaptation and susceptibility to Plasmodium falciparum infection

    PubMed Central

    Liu, Kun; Dong, Yuemei; Huang, Yuzheng; Rasgon, Jason L.; Agre, Peter

    2013-01-01

    Anopheles gambiae is a major vector mosquito for Plasmodium falciparum, the deadly pathogen causing most human malaria in sub-Saharan Africa. Synthesized in the fat body, trehalose is the predominant sugar in mosquito hemolymph. It not only provides energy but also protects the mosquito against desiccation and heat stresses. Trehalose enters the mosquito hemolymph by the trehalose transporter AgTreT1. In adult female A. gambiae, AgTreT1 is predominantly expressed in the fat body. We found that AgTreT1 expression is induced by environmental stresses such as low humidity or elevated temperature. AgTreT1 RNA silencing reduces the hemolymph trehalose concentration by 40%, and the mosquitoes succumb sooner after exposure to desiccation or heat. After an infectious blood meal, AgTreT1 RNA silencing reduces the number of P. falciparum oocysts in the mosquito midgut by over 70% compared with mock-injected mosquitoes. These data reveal important roles for AgTreT1 in stress adaptation and malaria pathogen development in a major vector mosquito. Thus, AgTreT1 may be a potential target for malaria vector control. PMID:24101462

  8. Shrinking a large dataset to identify variables associated with increased risk of Plasmodium falciparum infection in Western Kenya.

    PubMed

    Tremblay, M; Dahm, J S; Wamae, C N; De Glanville, W A; Fèvre, E M; Döpfer, D

    2015-12-01

    Large datasets are often not amenable to analysis using traditional single-step approaches. Here, our general objective was to apply imputation techniques, principal component analysis (PCA), elastic net and generalized linear models to a large dataset in a systematic approach to extract the most meaningful predictors for a health outcome. We extracted predictors for Plasmodium falciparum infection, from a large covariate dataset while facing limited numbers of observations, using data from the People, Animals, and their Zoonoses (PAZ) project to demonstrate these techniques: data collected from 415 homesteads in western Kenya, contained over 1500 variables that describe the health, environment, and social factors of the humans, livestock, and the homesteads in which they reside. The wide, sparse dataset was simplified to 42 predictors of P. falciparum malaria infection and wealth rankings were produced for all homesteads. The 42 predictors make biological sense and are supported by previous studies. This systematic data-mining approach we used would make many large datasets more manageable and informative for decision-making processes and health policy prioritization.

  9. Associations between the IL-4 -590 T allele and Plasmodium falciparum infection prevalence in asymptomatic Fulani of Mali.

    PubMed

    Vafa, Manijeh; Maiga, Bakary; Berzins, Klavs; Hayano, Masashi; Bereczky, Sandor; Dolo, Amagana; Daou, Modibo; Arama, Charles; Kouriba, Bourema; Färnert, Anna; Doumbo, Ogobara K; Troye-Blomberg, Marita

    2007-07-01

    In this study, we compared the genotype and allele frequencies of the IL-10 -1087 A/G and IL-4 -590 C/T single nucleotide polymorphisms in asymptomatic subjects of two sympatric ethnic tribes differing in susceptibility to malaria, the Fulani and the Dogon in Mali. The genotype data was correlated with ethnicity and malariometric indexes. A statistically significant inter-ethnic difference in allele and genotype frequency for both loci was noted (P<0.0001). Within the Fulani, the prevalence of Plasmodium falciparum infection, as detected by both microscopy and PCR, was associated with the IL-4 -590 T allele (P=0.005 and P=0.0005, respectively), whereas, no such associations were seen in the Dogon. Inter-ethnic differences in spleen rates, higher in the Fulani than the Dogon, were seen between T carriers (TT and CT) of both groups (P<0.0001). Parasite densities and number of concurrent clones did not vary between IL-4 genotypes within any of the studied groups. These results suggest an association between the IL-4 -590 T allele and P. falciparum prevalence within the Fulani but not the Dogon. No associations between IL-10 genotypes and studied malariometric indexes were observed in any of the two communities.

  10. Plasmodium falciparum Infection Induces Expression of a Mosquito Salivary Protein (Agaphelin) That Targets Neutrophil Function and Inhibits Thrombosis without Impairing Hemostasis

    PubMed Central

    Waisberg, Michael; Molina-Cruz, Alvaro; Mizurini, Daniella M.; Gera, Nidhi; Sousa, Beatriz C.; Ma, Dongying; Leal, Ana C.; Gomes, Tainá; Kotsyfakis, Michalis; Ribeiro, José M. C.; Lukszo, Jan; Reiter, Karine; Porcella, Stephen F.; Oliveira, Carlo J.; Monteiro, Robson Q.; Barillas-Mury, Carolina; Pierce, Susan K.; Francischetti, Ivo M. B.

    2014-01-01

    Background Invasion of mosquito salivary glands (SGs) by Plasmodium falciparum sporozoites is an essential step in the malaria life cycle. How infection modulates gene expression, and affects hematophagy remains unclear. Principal Findings Using Affimetrix chip microarray, we found that at least 43 genes are differentially expressed in the glands of Plasmodium falciparum-infected Anopheles gambiae mosquitoes. Among the upregulated genes, one codes for Agaphelin, a 58-amino acid protein containing a single Kazal domain with a Leu in the P1 position. Agaphelin displays high homology to orthologs present in Aedes sp and Culex sp salivary glands, indicating an evolutionarily expanded family. Kinetics and surface plasmon resonance experiments determined that chemically synthesized Agaphelin behaves as a slow and tight inhibitor of neutrophil elastase (KD∼10 nM), but does not affect other enzymes, nor promotes vasodilation, or exhibit antimicrobial activity. TAXIscan chamber assay revealed that Agaphelin inhibits neutrophil chemotaxis toward fMLP, affecting several parameter associated with cell migration. In addition, Agaphelin reduces paw edema formation and accumulation of tissue myeloperoxidase triggered by injection of carrageenan in mice. Agaphelin also blocks elastase/cathepsin-mediated platelet aggregation, abrogates elastase-mediated cleavage of tissue factor pathway inhibitor, and attenuates neutrophil-induced coagulation. Notably, Agaphelin inhibits neutrophil extracellular traps (NETs) formation and prevents FeCl3-induced arterial thrombosis, without impairing hemostasis. Conclusions Blockade of neutrophil elastase emerges as a novel antihemostatic mechanism in hematophagy; it also supports the notion that neutrophils and the innate immune response are targets for antithrombotic therapy. In addition, Agaphelin is the first antihemostatic whose expression is induced by Plasmodium sp infection. These results suggest that an important interplay takes place in

  11. Haptoglobin phenotype prevalence and cytokine profiles during Plasmodium falciparum infection in Dogon and Fulani ethnic groups living in Mali

    PubMed Central

    2013-01-01

    Background The Fulani are known to have a lower parasitaemia and less clinical episodes of malaria as compared to the Dogon sympatric ethnic group, living in Mali. Higher circulating malaria-specific antibody titers and increased pro-inflammatory cytokine levels have been shown in Fulani individuals. Several studies have tried to link haptoglobin (Hp) phenotypes with susceptibility to malaria, but without consensus. This study investigated the role of Hp phenotypes and cytokine levels in Dogon and Fulani during asymptomatic Plasmodium falciparum infection. Methods Two different cohorts were combined in this study: a 2008 cohort with 77 children aged between two and ten years and a 2001 cohort, with 82 children and adults, aged between 11 and 68 years. Hp phenotypes in plasma were measured by Western Blot. Circulating levels of sCD163, IL-6, IL-10, IFN-γ and TNF were measured by ELISA. Multiple regression analysis was performed to associate Hp phenotypes with cytokine profiles. In addition, in vitro stimulation of peripheral blood mononuclear cells (PBMCs) with Hp:Hb complexes was performed and cytokine release in corresponding supernatants were measured using cytometric bead array. Results The results revealed a higher Hp2-2 phenotype prevalence in the Fulani. The Hp2-2 phenotype was associated with a higher susceptibility to P. falciparum infection in Dogon, but not in Fulani. In concordance with previous studies, Fulani showed increased inflammatory mediators (IL-6, IFN-γ) and additionally also increased sCD163 levels compared to Dogon, irrespective of infection. Furthermore, infected individuals showed elevated sCD163 levels compared to uninfected individuals, in both Fulani and Dogon. Multiple regression analysis revealed that the Hp1-1 phenotype was associated with higher levels of TNF and IFN-γ, as compared to the Hp2-2 phenotype. In vitro stimulation of PBMCs with Hb:Hp1-1 complexes resulted in a pro-inflammatory cytokine profile, whilst stimulation with

  12. Spatial association with PTEX complexes defines regions for effector export into Plasmodium falciparum-infected erythrocytes

    PubMed Central

    Riglar, David T.; Rogers, Kelly L.; Hanssen, Eric; Turnbull, Lynne; Bullen, Hayley E.; Charnaud, Sarah C.; Przyborski, Jude; Gilson, Paul R.; Whitchurch, Cynthia B.; Crabb, Brendan S.; Baum, Jake; Cowman, Alan F.

    2013-01-01

    Export of proteins into the infected erythrocyte is critical for malaria parasite survival. The majority of effector proteins are thought to export via a proteinaceous translocon, resident in the parasitophorous vacuole membrane surrounding the parasite. Identification of the Plasmodium translocon of exported proteins and its biochemical association with exported proteins suggests it performs this role. Direct evidence for this, however, is lacking. Here using viable purified Plasmodium falciparum merozoites and three-dimensional structured illumination microscopy, we investigate remodelling events immediately following parasite invasion. We show that multiple complexes of the Plasmodium translocon of exported proteins localize together in foci that dynamically change in clustering behaviour. Furthermore, we provide conclusive evidence of spatial association between exported proteins and exported protein 2, a core component of the Plasmodium translocon of exported proteins, during native conditions and upon generation of translocation intermediates. These data provide the most direct cellular evidence to date that protein export occurs at regions of the parasitophorous vacuole membrane housing the Plasmodium translocon of exported proteins complex. PMID:23361006

  13. Plasmodium falciparum infection increases Anopheles gambiae attraction to nectar sources and sugar uptake

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Plasmodium parasites are known to manipulate the behaviour of their vectors so as to enhance their transmission. However, it is unknown if this vector manipulation also affects mosquito-plant interaction and sugar uptake. Dual-choice olfactometer and probing assays were used to study plant seeking b...

  14. Epidemiology of subpatent Plasmodium falciparum infection: implications for detection of hotspots with imperfect diagnostics

    PubMed Central

    2013-01-01

    Background At the local level, malaria transmission clusters in hotspots, which may be a group of households that experience higher than average exposure to infectious mosquitoes. Active case detection often relying on rapid diagnostic tests for mass screen and treat campaigns has been proposed as a method to detect and treat individuals in hotspots. Data from a cross-sectional survey conducted in north-western Tanzania were used to examine the spatial distribution of Plasmodium falciparum and the relationship between household exposure and parasite density. Methods Dried blood spots were collected from consenting individuals from four villages during a survey conducted in 2010. These were analysed by PCR for the presence of P. falciparum, with the parasite density of positive samples being estimated by quantitative PCR. Household exposure was estimated using the distance-weighted PCR prevalence of infection. Parasite density simulations were used to estimate the proportion of infections that would be treated using a screen and treat approach with rapid diagnostic tests (RDT) compared to targeted mass drug administration (tMDA) and Mass Drug Administration (MDA). Results Polymerase chain reaction PCR analysis revealed that of the 3,057 blood samples analysed, 1,078 were positive. Mean distance-weighted PCR prevalence per household was 34.5%. Parasite density was negatively associated with transmission intensity with the odds of an infection being subpatent increasing with household exposure (OR 1.09 per 1% increase in exposure). Parasite density was also related to age, being highest in children five to ten years old and lowest in those > 40 years. Simulations of different tMDA strategies showed that treating all individuals in households where RDT prevalence was above 20% increased the number of infections that would have been treated from 43 to 55%. However, even with this strategy, 45% of infections remained untreated. Conclusion The negative relationship

  15. Detection of Plasmodium falciparum-infected red blood cells by optical stretching

    NASA Astrophysics Data System (ADS)

    Mauritz, Jakob M. A.; Tiffert, Teresa; Seear, Rachel; Lautenschläger, Franziska; Esposito, Alessandro; Lew, Virgilio L.; Guck, Jochen; Kaminski, Clemens F.

    2010-05-01

    We present the application of a microfluidic optical cell stretcher to measure the elasticity of malaria-infected red blood cells. The measurements confirm an increase in host cell rigidity during the maturation of the parasite Plasmodium falciparum. The device combines the selectivity and sensitivity of single-cell elasticity measurements with a throughput that is higher than conventional single-cell techniques. The method has potential to detect early stages of infection with excellent sensitivity and high speed.

  16. A direct comparison of real time PCR on plasma and blood to detect Plasmodium falciparum infection in children

    PubMed Central

    2012-01-01

    Background Estimation of Plasmodium falciparum parasitaemia can vary with the method used and time of sampling. Quantitative real time PCR (qPCR) on whole blood or plasma samples has previously been shown to be more sensitive than thick film microscopy. However the efficiencies of each method have not been compared using samples obtained from infants less than one year old. Methods A multiple of statistical approaches were used to compare the performance of qPCR on whole blood or plasma to detect the 18 S ribosomal gene of P. falciparum in 548 samples from children aged 2.5 or 24 months. Parasite prevalence in matched samples was compared using Mcnemar’s test and agreement of positive results quantified as Kappa scores. Parasite prevalences between different age groups were compared by Fisher’s test. Results from analyses by thick film microscopy were also available from children at 24 months and their correlation to each qPCR method examined by the Spearman’s test. Finally the association of P. falciparum infection with the incidence of multiple malaria episodes from contact to 24 months of age was evaluated using negative binomial regression. Results These analyses showed that qPCR from whole blood detected approximately 3-fold more cases of infection than plasma qPCR. Both qPCR methods agreed well with each other although qPCR from plasma had a greater agreement with microscopy (96.85%) than did qPCR from blood (69.7%). At 24 months the prevalence of infection detected by all methods was associated with anaemia (p < 0.05). Conclusions The data presented here demonstrates that low levels of parasitaemia are better detected by qPCR using parasite DNA from whole blood than from plasma. However plasma samples provide a viable substitute when parasite smears are unavailable. PMID:22704637

  17. Equivalent susceptibility of Anopheles gambiae M and S molecular forms and Anopheles arabiensis to Plasmodium falciparum infection in Burkina Faso

    PubMed Central

    2013-01-01

    Background The Anopheles gambiae sensu lato (s.l.) species complex in Burkina Faso consists of Anopheles arabiensis, and molecular forms M and S of Anopheles gambiae sensu stricto (s.s.). Previous studies comparing the M and S forms for level of infection with Plasmodium falciparum have yielded conflicting results. Methods Mosquito larvae were sampled from natural pools, reared to adulthood under controlled conditions, and challenged with natural P. falciparum by experimental feeding with blood from gametocyte carriers. Oocyst infection prevalence and intensity was determined one week after infection. DNA from carcasses was genotyped to identify species and molecular form. Results In total, 7,400 adult mosquitoes grown from wild-caught larvae were challenged with gametocytes in 29 experimental infections spanning four transmission seasons. The overall infection prevalence averaged 40.7% for A. gambiae M form, 41.4% for A. gambiae S form, and 40.1% for A. arabiensis. There was no significant difference in infection prevalence or intensity between the three population groups. Notably, infection experiments in which the population groups were challenged in parallel on the same infective blood displayed less infection difference between population groups, while infections with less balanced composition of population groups had lower statistical power and displayed apparent differences that fluctuated more often from the null average. Conclusion The study clearly establishes that, at the study site in Burkina Faso, there is no difference in genetic susceptibility to P. falciparum infection between three sympatric population groups of the A. gambiae s.l. complex. Feeding the mosquito groups on the same infective blood meal greatly increases statistical power. Conversely, comparison of the different mosquito groups between, rather than within, infections yields larger apparent difference between mosquito groups, resulting from lower statistical power and greater noise

  18. Evidence of promiscuous endothelial binding by Plasmodium falciparum-infected erythrocytes.

    PubMed

    Esser, Claudia; Bachmann, Anna; Kuhn, Daniela; Schuldt, Kathrin; Förster, Birgit; Thiel, Meike; May, Jürgen; Koch-Nolte, Friedrich; Yáñez-Mó, María; Sánchez-Madrid, Francisco; Schinkel, Alfred H; Jalkanen, Sirpa; Craig, Alister G; Bruchhaus, Iris; Horstmann, Rolf D

    2014-05-01

    The adhesion of infected red blood cells (iRBCs) to human endothelium is considered a key event in the pathogenesis of cerebral malaria and other life-threatening complications caused by the most prevalent malaria parasite Plasmodium falciparum. In the past 30 years, 14 endothelial receptors for iRBCs have been identified. Exposing 10 additional surface proteins of endothelial cells to a mixture of P.  falciparum isolates from three Ghanaian malaria patients, we identified seven new iRBC receptors, all expressed in brain vessels. This finding strongly suggests that endothelial binding of P.  falciparum iRBCs is promiscuous and may use a combination of endothelial surface moieties.

  19. Mosquito Passage Dramatically Changes var Gene Expression in Controlled Human Plasmodium falciparum Infections

    PubMed Central

    Bachmann, Anna; Petter, Michaela; Krumkamp, Ralf; Esen, Meral; Held, Jana; Scholz, Judith A. M.; Li, Tao; Sim, B. Kim Lee; Hoffman, Stephen L.; Kremsner, Peter G.; Mordmüller, Benjamin; Duffy, Michael F.; Tannich, Egbert

    2016-01-01

    Virulence of the most deadly malaria parasite Plasmodium falciparum is linked to the variant surface antigen PfEMP1, which is encoded by about 60 var genes per parasite genome. Although the expression of particular variants has been associated with different clinical outcomes, little is known about var gene expression at the onset of infection. By analyzing controlled human malaria infections via quantitative real-time PCR, we show that parasite populations from 18 volunteers expressed virtually identical transcript patterns that were dominated by the subtelomeric var gene group B and, to a lesser extent, group A. Furthermore, major changes in composition and frequency of var gene transcripts were detected between the parental parasite culture that was used to infect mosquitoes and Plasmodia recovered from infected volunteers, suggesting that P. falciparum resets its var gene expression during mosquito passage and starts with the broad expression of a specific subset of var genes when entering the human blood phase. PMID:27070311

  20. Mosquito Passage Dramatically Changes var Gene Expression in Controlled Human Plasmodium falciparum Infections.

    PubMed

    Bachmann, Anna; Petter, Michaela; Krumkamp, Ralf; Esen, Meral; Held, Jana; Scholz, Judith A M; Li, Tao; Sim, B Kim Lee; Hoffman, Stephen L; Kremsner, Peter G; Mordmüller, Benjamin; Duffy, Michael F; Tannich, Egbert

    2016-04-01

    Virulence of the most deadly malaria parasite Plasmodium falciparum is linked to the variant surface antigen PfEMP1, which is encoded by about 60 var genes per parasite genome. Although the expression of particular variants has been associated with different clinical outcomes, little is known about var gene expression at the onset of infection. By analyzing controlled human malaria infections via quantitative real-time PCR, we show that parasite populations from 18 volunteers expressed virtually identical transcript patterns that were dominated by the subtelomeric var gene group B and, to a lesser extent, group A. Furthermore, major changes in composition and frequency of var gene transcripts were detected between the parental parasite culture that was used to infect mosquitoes and Plasmodia recovered from infected volunteers, suggesting that P. falciparum resets its var gene expression during mosquito passage and starts with the broad expression of a specific subset of var genes when entering the human blood phase.

  1. Quantitative non-invasive intracellular imaging of Plasmodium falciparum infected human erythrocytes

    NASA Astrophysics Data System (ADS)

    Edward, Kert; Farahi, Faramarz

    2014-05-01

    Malaria is a virulent pathological condition which results in over a million annual deaths. The parasitic agent Plasmodium falciparum has been extensively studied in connection with this epidemic but much remains unknown about its development inside the red blood cell host. Optical and fluorescence imaging are among the two most common procedures for investigating infected erythrocytes but both require the introduction of exogenous contrast agents. In this letter, we present a procedure for the non-invasive in situ imaging of malaria infected red blood cells. The procedure is based on the utilization of simultaneously acquired quantitative phase and independent topography data to extract intracellular information. Our method allows for the identification of the developmental stages of the parasite and facilitates in situ analysis of the morphological changes associated with the progression of this disease. This information may assist in the development of efficacious treatment therapies for this condition.

  2. A two-compartment model of osmotic lysis in Plasmodium falciparum-infected erythrocytes.

    PubMed

    Wagner, Marissa A; Andemariam, Biree; Desai, Sanjay A

    2003-01-01

    We recently identified a voltage-dependent anion channel on the surface of human red blood cells (RBCs) infected with the malaria parasite, Plasmodium falciparum. This channel, the plasmodial erythrocyte surface anion channel (PESAC), likely accounts for the increased permeability of infected RBCs to various small solutes, as assessed quantitatively with radioisotope flux and patch-clamp studies. Whereas this increased permeability has also been studied by following osmotic lysis of infected cells in permeant solutes, these experiments have been limited to qualitative comparisons of lysis rates. To permit more quantitative examination of lysis rates, we have developed a mathematical model for osmotic fragility of infected cells based on diffusional uptake via PESAC and the two-compartment geometry of infected RBCs. This model, combined with a simple light scattering assay designed to track osmotic lysis precisely, produced permeability coefficients that match both previous isotope flux and patch-clamp estimates. Our model and light scattering assay also revealed Michaelian kinetics for inhibition of PESAC by furosemide, suggesting a 1:1 stoichiometry for their interaction. PMID:12524269

  3. The influence of urbanisation on measures of Plasmodium falciparum infection prevalence in East Africa

    PubMed Central

    Omumbo, J.A.; Guerra, C.A.; Hay, S.I.; Snow, R.W.

    2011-01-01

    There is a growing interest in the effects of urbanisation in Africa on Plasmodium falciparum risks and disease outcomes. We undertook a review of published and unpublished literature to identify parasite survey data from communities in East Africa. Data were selected to represent the most reliable and contemporary estimates of infection prevalence and were categorised by urban or rural status using a number of approaches. We identified 329 spatially distinct surveys undertaken since 1980 in the sub-region of which 37 were undertaken in urban settlements and 292 in rural settlements. Overall rural settlements reported significantly higher parasite prevalence among children aged 0–14 than urban settlements (on average 10% higher infection rates; p < 0.05). No urban settlements recorded parasite prevalence in excess of 75%. In areas of East Africa where climatic conditions are likely to support higher parasite transmission, the rural–urban difference was most marked. There was a significant trend towards documenting higher classes of parasite prevalence in rural compared to urban settlements (p < 0.05) and the mean difference between rural and urban samples was 18% (p < 0.001). These results further highlight the need to better define urban extents in Africa in order to capture the non-climatic determinants of infection and disease risk and provide a more informed approach to describing the burden of disease across the continent. PMID:15589793

  4. Placental Malaria in Colombia: Histopathologic Findings in Plasmodium vivax and P. falciparum Infections

    PubMed Central

    Carmona-Fonseca, Jaime; Arango, Eliana; Maestre, Amanda

    2013-01-01

    Studies on gestational malaria and placental malaria have been scarce in malaria-endemic areas of the Western Hemisphere. To describe the histopathology of placental malaria in Colombia, a longitudinal descriptive study was conducted. In this study, 179 placentas were studied by histologic analysis (112 with gestational malaria and 67 negative for malaria). Placental malaria was confirmed in 22.35%, 50.0% had previous infections, and 47.5% had acute infections. Typical malaria-associated changes were observed in 37%. The most common changes were villitis, intervillitis, deciduitis, increased fibrin deposition, increased syncytial knots, mononuclear (monocytes/macrophages and lymphocytes), polymorphonuclear cell infiltration, and trophozoites in fetal erythrocytes. No association was found between type of placental changes observed and histopathologic classification of placental malaria. The findings are consistent with those reported for placental malaria in other regions. Plasmodium vivax was the main parasite responsible for placental and gestational malaria, but its role in the pathogenesis of placental malaria was not conclusive. PMID:23546807

  5. Comparison of Plasmodium falciparum infections in Panamanian and Colombian owl monkeys.

    PubMed

    Rossan, R N; Harper, J S; Davidson, D E; Escajadillo, A; Christensen, H A

    1985-11-01

    Parameters of blood-induced infections of the Vietnam Oak Knoll, Vietnam Smith, and Uganda Palo Alto strains of Plasmodium falciparum studied in 395 Panamanian owl monkeys in this laboratory between 1976-1984 were compared with those reported from another laboratory for 665 Colombian owl monkeys, studied between 1968-1975, and, at the time, designated Aotus trivirgatus griseimembra. The virulence of these strains was less in Panamanian than in Colombian owl monkeys, as indicated by lower mortality rates of the Panamanian monkeys during the first 30 days of patency. Maximum parasitemias of the Vietnam Smith and Uganda Palo Alto strain, in Panamanian owl monkeys dying during the first 15 days of patent infection, were significantly higher than in Colombian owl monkeys. Panamanian owl monkeys that survived the primary attack had significantly higher maximum parasitemias than the surviving Colombian owl monkeys. Peak parasitemias were attained significantly earlier after patency in Panamanian than in Colombian owl monkeys, irrespective of the strain of P. falciparum. More Panamanian than Colombian owl monkeys evidenced self-limited infection after the primary attack of either the Vietnam Smith or Uganda Palo Alto strain. The duration of the primary attacks and recrudescences were significantly shorter in Panamanian than in Colombian owl monkeys. Mean peak parasitemias during recrudescence were usually higher in Panamanian owl monkeys than in Colombian monkeys. Differences of infection parameters were probably attributable, in part, to geographical origin of the two monkey hosts and parasite strains. PMID:3914842

  6. A kinetic fluorescence assay reveals unusual features of Ca++ uptake in Plasmodium falciparum-infected erythrocytes

    PubMed Central

    2014-01-01

    Background To facilitate development within erythrocytes, malaria parasites increase their host cell uptake of diverse solutes including Ca++. The mechanism and molecular basis of increased Ca++ permeability remains less well studied than that of other solutes. Methods Based on an appropriate Ca++ affinity and its greater brightness than related fluorophores, Fluo-8 was selected and used to develop a robust fluorescence-based assay for Ca++ uptake by human erythrocytes infected with Plasmodium falciparum. Results Both uninfected and infected cells exhibited a large Ca++-dependent fluorescence signal after loading with the Fluo-8 dye. Probenecid, an inhibitor of erythrocyte organic anion transporters, abolished the fluorescence signal in uninfected cells; in infected cells, this agent increased fluorescence via mechanisms that depend on parasite genotype. Kinetic fluorescence measurements in 384-well microplates revealed that the infected cell Ca++ uptake is not mediated by the plasmodial surface anion channel (PSAC), a parasite nutrient channel at the host membrane; it also appears to be distinct from mammalian Ca++ channels. Imaging studies confirmed a low intracellular Ca++ in uninfected cells and higher levels in both the host and parasite compartments of infected cells. Parasite growth inhibition studies revealed a conserved requirement for extracellular Ca++. Conclusions Nondestructive loading of Fluo-8 into human erythrocytes permits measurement of Ca++ uptake kinetics. The greater Ca++ permeability of cells infected with malaria parasites is apparent when probenecid is used to inhibit Fluo-8 efflux at the host membrane. This permeability is mediated by a distinct pathway and may be essential for intracellular parasite development. The miniaturized assay presented here should help clarify the precise transport mechanism and may identify inhibitors suitable for antimalarial drug development. PMID:24885754

  7. Sustained activation of Akt elicits mitochondrial dysfunction to block Plasmodium falciparum infection in the mosquito host.

    PubMed

    Luckhart, Shirley; Giulivi, Cecilia; Drexler, Anna L; Antonova-Koch, Yevgeniya; Sakaguchi, Danielle; Napoli, Eleonora; Wong, Sarah; Price, Mark S; Eigenheer, Richard; Phinney, Brett S; Pakpour, Nazzy; Pietri, Jose E; Cheung, Kong; Georgis, Martha; Riehle, Michael

    2013-02-01

    The overexpression of activated, myristoylated Akt in the midgut of female transgenic Anopheles stephensi results in resistance to infection with the human malaria parasite Plasmodium falciparum but also decreased lifespan. In the present study, the understanding of mitochondria-dependent midgut homeostasis has been expanded to explain this apparent paradox in an insect of major medical importance. Given that Akt signaling is essential for cell growth and survival, we hypothesized that sustained Akt activation in the mosquito midgut would alter the balance of critical pathways that control mitochondrial dynamics to enhance parasite killing at some cost to survivorship. Toxic reactive oxygen and nitrogen species (RNOS) rise to high levels in the midgut after blood feeding, due to a combination of high NO production and a decline in FOXO-dependent antioxidants. Despite an apparent increase in mitochondrial biogenesis in young females (3 d), energy deficiencies were apparent as decreased oxidative phosphorylation and increased [AMP]/[ATP] ratios. In addition, mitochondrial mass was lower and accompanied by the presence of stalled autophagosomes in the posterior midgut, a critical site for blood digestion and stem cell-mediated epithelial maintenance and repair, and by functional degradation of the epithelial barrier. By 18 d, the age at which An. stephensi would transmit P. falciparum to human hosts, mitochondrial dysfunction coupled to Akt-mediated repression of autophagy/mitophagy was more evident and midgut epithelial structure was markedly compromised. Inhibition of RNOS by co-feeding of the nitric-oxide synthase inhibitor L-NAME at infection abrogated Akt-dependent killing of P. falciparum that begins within 18 h of infection in 3-5 d old mosquitoes. Hence, Akt-induced changes in mitochondrial dynamics perturb midgut homeostasis to enhance parasite resistance and decrease mosquito infective lifespan. Further, quality control of mitochondrial function in the

  8. Sustained Activation of Akt Elicits Mitochondrial Dysfunction to Block Plasmodium falciparum Infection in the Mosquito Host

    PubMed Central

    Drexler, Anna L.; Antonova-Koch, Yevgeniya; Sakaguchi, Danielle; Napoli, Eleonora; Wong, Sarah; Price, Mark S.; Eigenheer, Richard; Phinney, Brett S.; Pakpour, Nazzy; Pietri, Jose E.; Cheung, Kong; Georgis, Martha; Riehle, Michael

    2013-01-01

    The overexpression of activated, myristoylated Akt in the midgut of female transgenic Anopheles stephensi results in resistance to infection with the human malaria parasite Plasmodium falciparum but also decreased lifespan. In the present study, the understanding of mitochondria-dependent midgut homeostasis has been expanded to explain this apparent paradox in an insect of major medical importance. Given that Akt signaling is essential for cell growth and survival, we hypothesized that sustained Akt activation in the mosquito midgut would alter the balance of critical pathways that control mitochondrial dynamics to enhance parasite killing at some cost to survivorship. Toxic reactive oxygen and nitrogen species (RNOS) rise to high levels in the midgut after blood feeding, due to a combination of high NO production and a decline in FOXO-dependent antioxidants. Despite an apparent increase in mitochondrial biogenesis in young females (3 d), energy deficiencies were apparent as decreased oxidative phosphorylation and increased [AMP]/[ATP] ratios. In addition, mitochondrial mass was lower and accompanied by the presence of stalled autophagosomes in the posterior midgut, a critical site for blood digestion and stem cell-mediated epithelial maintenance and repair, and by functional degradation of the epithelial barrier. By 18 d, the age at which An. stephensi would transmit P. falciparum to human hosts, mitochondrial dysfunction coupled to Akt-mediated repression of autophagy/mitophagy was more evident and midgut epithelial structure was markedly compromised. Inhibition of RNOS by co-feeding of the nitric-oxide synthase inhibitor L-NAME at infection abrogated Akt-dependent killing of P. falciparum that begins within 18 h of infection in 3–5 d old mosquitoes. Hence, Akt-induced changes in mitochondrial dynamics perturb midgut homeostasis to enhance parasite resistance and decrease mosquito infective lifespan. Further, quality control of mitochondrial function in the

  9. Trends in multiplicity of Plasmodium falciparum infections among asymptomatic residents in the middle belt of Ghana

    PubMed Central

    2013-01-01

    Background Malaria is the most important cause of mortality and morbidity in children living in the Kintampo districts in the middle part of Ghana. This study has investigated the multiplicity of infection (MOI) within asymptomatic residents of the Kintampo districts, and the influence of age and seasonality on MOI, by studying the distribution of the polymorphic Plasmodium falciparum antigen merozoite surface protein 2 (MSP2). Methods DNA was extracted from an asymptomatic cohort of children and adults infected with P. falciparum during the period November 2003 to October 2004. Polymerase chain reaction was carried out and multiplicity of infection (MOI) was determined. Results Children under 10 years of age had an average MOI of 2.3 while adults 18 years and above had an average MOI of 1.4. Children below five years had high and low average MOIs of 2.8 in the March/April survey and 0.9 in the May/June survey respectively. A similar trend in the monthly distribution of MOI was observed for the entire cohort. IC/3D7 strains outnumbered the FC27 strains throughout the year by a ratio of about 4:1 with the difference between the prevalence of the two strains being least marked in the March/April survey, at the beginning of the rainy season. MOI was not linked to the level of malaria transmission as measured by the entomological inoculation rate. Discussion/conclusion The impact of interventions, introduced since this baseline study was carried out on the parasite diversity of asymptomatic residents will be the subject of further investigations. PMID:23327681

  10. Absence of an association between Plasmodium falciparum infection and post-ivermectin Loa-related non-neurologic serious adverse events.

    PubMed

    Fokom-Domgue, Joël; Pion, Sébastien D; Gounoue, Raceline; Akame, Julie; Nguipdop-Djomo, Patrick; Twum-Danso, Nana A Y; Thylefors, Björn; Boussinesq, Michel; Kamgno, Joseph

    2014-02-01

    Although ivermectin treatment can induce serious adverse events (SAEs) in individuals harboring high Loa loa microfilaremia (mf), not all patients with high mf levels develop such reactions, suggesting that cofactors may be involved. A study was conducted in Cameroon to investigate the possible role of Plasmodium coinfection at the time of ivermectin treatment in the development of SAEs. Before their first ivermectin treatment, thick smears were obtained from 4,175 individuals to determine the burden of Plasmodium sp., L. loa, and Mansonella perstans. After treatment, 18 (4.3 per 1,000) patients developed a non-neurologic SAE. Logistic regression analysis, adjusting for age, sex, P. falciparum infection, and M. perstans infection intensities, confirmed that L. loa mf was the main risk factor for SAEs. We found no evidence that coinfection with P. falciparum at the time of ivermectin treatment was associated with the occurrence of Loa-related SAEs in this population. PMID:24420781

  11. Fever in uncomplicated Plasmodium falciparum infection: effects of quinine and paracetamol.

    PubMed

    Krishna, S; Supanaranond, W; Pukrittayakamee, S; ter Kuile, F; Supputamangkol, Y; Attatamsoonthorn, K; Ruprah, M; White, N J

    1995-01-01

    The effects of quinine and paracetamol on fever were studied in 21 adult patients with acute uncomplicated falciparum malaria. Quinine alone (n = 7) had no significant effect on fever, whereas paracetamol given 2 h after quinine (n = 7) or 2 h before quinine (n = 7) reduced temperature by a mean of 2.1 degrees C (standard deviation [SD] 0.95) and 2.1 degrees C (SD 0.79) respectively. A temperature reduction of 1 degree C was associated with a mean decrement of 9.7 beats/min (SD 3.3) in the pulse rate. Quinine does not possess useful antipyretic activity.

  12. Declining Responsiveness of Plasmodium falciparum Infections to Artemisinin-Based Combination Treatments on the Kenyan Coast

    PubMed Central

    Borrmann, Steffen; Sasi, Philip; Mwai, Leah; Bashraheil, Mahfudh; Abdallah, Ahmed; Muriithi, Steven; Frühauf, Henrike; Schaub, Barbara; Pfeil, Johannes; Peshu, Judy; Hanpithakpong, Warunee; Rippert, Anja; Juma, Elizabeth; Tsofa, Benjamin; Mosobo, Moses; Lowe, Brett; Osier, Faith; Fegan, Greg; Lindegårdh, Niklas; Nzila, Alexis; Peshu, Norbert; Mackinnon, Margaret; Marsh, Kevin

    2011-01-01

    Background The emergence of artemisinin-resistant P. falciparum malaria in South-East Asia highlights the need for continued global surveillance of the efficacy of artemisinin-based combination therapies. Methods On the Kenyan coast we studied the treatment responses in 474 children 6–59 months old with uncomplicated P. falciparum malaria in a randomized controlled trial of dihydroartemisinin-piperaquine vs. artemether-lumefantrine from 2005 to 2008. (ISRCTN88705995) Results The proportion of patients with residual parasitemia on day 1 rose from 55% in 2005–2006 to 87% in 2007–2008 (odds ratio, 5.4, 95%CI, 2.7–11.1; P<0.001) and from 81% to 95% (OR, 4.1, 95%CI, 1.7–9.9; P = 0.002) in the DHA-PPQ and AM-LM groups, respectively. In parallel, Kaplan-Meier estimated risks of apparent recrudescent infection by day 84 increased from 7% to 14% (P = 0.1) and from 6% to 15% (P = 0.05) with DHA-PPQ and AM-LM, respectively. Coinciding with decreasing transmission in the study area, clinical tolerance to parasitemia (defined as absence of fever) declined between 2005–2006 and 2007–2008 (OR body temperature >37.5°C, 2.8, 1.9–4.1; P<0.001). Neither in vitro sensitivity of parasites to DHA nor levels of antibodies against parasite extract accounted for parasite clearance rates or changes thereof. Conclusions The significant, albeit small, decline through time of parasitological response rates to treatment with ACTs may be due to the emergence of parasites with reduced drug sensitivity, to the coincident reduction in population-level clinical immunity, or both. Maintaining the efficacy of artemisinin-based therapy in Africa would benefit from a better understanding of the mechanisms underlying reduced parasite clearance rates. Trial Registration Controlled-Trials.com ISRCTN88705995 PMID:22102856

  13. Monoclonal antibody OKM5 inhibits the in vitro binding of Plasmodium falciparum-infected erythrocytes to monocytes, endothelial, and C32 melanoma cells

    SciTech Connect

    Barnwell, J.W.; Ockenhouse, C.F.; Knowles, D.M. II

    1985-11-01

    Plasmodium falciparum-infected erythrocytes bind in vitro to human endothelial cells, monocytes, and a certain melanoma cell line. Evidence suggests that this interaction is mediated by similar mechanisms which lead to the sequestration of parasitized erythrocytes in vivo through their attachment to endothelial cells of small blood vessels. They show here the monoclonal antibody OKM5, previously shown to react with the membranes of endothelial cells, monocyte,s and platelets, also reacts with the C32 melanoma cell line which also binds P. falciparum-infected erythrocytes. At relatively low concentrations, OKM5 inhibits and reverses the in vitro adherence of infected erythrocytes to target cells. As with monocytes, OKM5 antibody recognizes an /sup 125/I-labeled protein of approximately 88 Kd on the surface of C32 melanoma cells. It seems likely, therefore, that the 88 Kd polypeptide plays a role in cytoadherence, possibly as the receptor or part of a receptor for a ligand on the surface of infected erythrocytes.

  14. Copper pathways in Plasmodium falciparum infected erythrocytes indicate an efflux role for the copper P-ATPase.

    PubMed

    Rasoloson, Dominique; Shi, Lirong; Chong, Curtis R; Kafsack, Bjorn F; Sullivan, David J

    2004-08-01

    Copper, like iron, is a transition metal that can generate oxygen radicals by the Fenton reaction. The Plasmodium parasite invades an erythrocyte host cell containing 20 microM copper, of which 70% is contained in the Cu/Zn SOD (cuprozinc superoxide dismutase). In the present study, we follow the copper pathways in the Plasmodium-infected erythrocyte. Metal-determination analysis shows that the total copper content of Percoll-purified trophozoite-stage-infected erythrocytes is 66% that of uninfected erythrocytes. This decrease parallels the decrease seen in Cu/Zn SOD levels in parasite-infected erythrocytes. Neocuproine, an intracellular copper chelator, arrests parasites at the ring-to-trophozoite stage transition and also specifically decreases intraparasitic levels of Cu/Zn SOD and catalase. Up to 150 microM BCS (2,9-dimethyl-4,7-diphenyl-1,10-phenanthrolinedisulphonic acid), an extracellular copper chelator, has no effect on parasite growth. We characterized a single copy PfCuP-ATPase (Plasmodium falciparum copper P-ATPase) transporter, which, like the Crypto-sporidium parvum copper P-ATPase, has a single copper-binding domain: 'Met-Xaa-Cys-Xaa-Xaa-Cys'. Recombinant expression of the N-terminal metal-binding domain reveals that the protein specifically binds reduced copper. Transcription of the PfCuP-ATPase gene is the highest at late ring stage/early trophozoite, and is down-regulated in the presence of neocuproine. Immunofluorescence and electron microscopy indicate the transporter to be both in the parasite and on the erythrocyte membrane. Both the decrease in total copper and the location of the PfCuP-ATPase gene indicate a copper-efflux pathway from the infected erythrocyte.

  15. Confirmation of the protective effect of Ascaris lumbricoides on Plasmodium falciparum infection: results of a randomized trial in Madagascar.

    PubMed

    Brutus, Laurent; Watier, Laurence; Hanitrasoamampionona, Virginie; Razanatsoarilala, Hélène; Cot, Michel

    2007-12-01

    A controlled randomized trial of anti-helminthic treatment was undertaken in 1996-1997 in a rural area of Madagascar where populations were simultaneously infected with Ascaris lumbricoides, Plasmodium falciparum, and Schistosoma mansoni. Levamisole was administered bimonthly to 107 subjects, whereas 105 were controls. Levamisole was highly effective in reducing Ascaris egg loads in the treated group (P < 10(-3) at all visits), whereas it had no effect on schistosomiasis. Subjects 5-14 years of age, treated with levamisole, had a significant increase of their P. falciparum densities compared with controls (P = 0.003). There was no effect of the treatment on children 6 months to 4 years of age, nor on adults > 15 years of age. This study confirms the results of a randomized trial, which showed a negative interaction in those > 5 years of age between Ascaris and malaria parasite density in another Malagasy population, submitted to a higher malaria transmission.

  16. Demonstration of specific binding of heparin to Plasmodium falciparum-infected vs. non-infected red blood cells by single-molecule force spectroscopy

    NASA Astrophysics Data System (ADS)

    Valle-Delgado, Juan José; Urbán, Patricia; Fernàndez-Busquets, Xavier

    2013-04-01

    Glycosaminoglycans (GAGs) play an important role in the sequestration of Plasmodium falciparum-infected red blood cells (pRBCs) in the microvascular endothelium of different tissues, as well as in the formation of small clusters (rosettes) between infected and non-infected red blood cells (RBCs). Both sequestration and rosetting have been recognized as characteristic events in severe malaria. Here we have used heparin and pRBCs infected by the 3D7 strain of P. falciparum as a model to study GAG-pRBC interactions. Fluorescence microscopy and fluorescence-assisted cell sorting assays have shown that exogenously added heparin has binding specificity for pRBCs (preferentially for those infected with late forms of the parasite) vs. RBCs. Heparin-pRBC adhesion has been probed by single-molecule force spectroscopy, obtaining an average binding force ranging between 28 and 46 pN depending on the loading rate. No significant binding of heparin to non-infected RBCs has been observed in control experiments. This work represents the first approach to quantitatively evaluate GAG-pRBC molecular interactions at the individual molecule level.Glycosaminoglycans (GAGs) play an important role in the sequestration of Plasmodium falciparum-infected red blood cells (pRBCs) in the microvascular endothelium of different tissues, as well as in the formation of small clusters (rosettes) between infected and non-infected red blood cells (RBCs). Both sequestration and rosetting have been recognized as characteristic events in severe malaria. Here we have used heparin and pRBCs infected by the 3D7 strain of P. falciparum as a model to study GAG-pRBC interactions. Fluorescence microscopy and fluorescence-assisted cell sorting assays have shown that exogenously added heparin has binding specificity for pRBCs (preferentially for those infected with late forms of the parasite) vs. RBCs. Heparin-pRBC adhesion has been probed by single-molecule force spectroscopy, obtaining an average binding force

  17. Pf155/RESA protein influences the dynamic microcirculatory behavior of ring-stage Plasmodium falciparum infected red blood cells

    NASA Astrophysics Data System (ADS)

    Diez-Silva, Monica; Park, Yongkeun; Huang, Sha; Bow, Hansen; Mercereau-Puijalon, Odile; Deplaine, Guillaume; Lavazec, Catherine; Perrot, Sylvie; Bonnefoy, Serge; Feld, Michael S.; Han, Jongyoon; Dao, Ming; Suresh, Subra

    2012-08-01

    Proteins exported by Plasmodium falciparum to the red blood cell (RBC) membrane modify the structural properties of the parasitized RBC (Pf-RBC). Although quasi-static single cell assays show reduced ring-stage Pf-RBCs deformability, the parameters influencing their microcirculatory behavior remain unexplored. Here, we study the dynamic properties of ring-stage Pf-RBCs and the role of the parasite protein Pf155/Ring-Infected Erythrocyte Surface Antigen (RESA). Diffraction phase microscopy revealed RESA-driven decreased Pf-RBCs membrane fluctuations. Microfluidic experiments showed a RESA-dependent reduction in the Pf-RBCs transit velocity, which was potentiated at febrile temperature. In a microspheres filtration system, incubation at febrile temperature impaired traversal of RESA-expressing Pf-RBCs. These results show that RESA influences ring-stage Pf-RBCs microcirculation, an effect that is fever-enhanced. This is the first identification of a parasite factor influencing the dynamic circulation of young asexual Pf-RBCs in physiologically relevant conditions, offering novel possibilities for interventions to reduce parasite survival and pathogenesis in its human host.

  18. Plasmodium falciparum-Infected Erythrocytes and β-Hematin Induce Partial Maturation of Human Dendritic Cells and Increase Their Migratory Ability in Response to Lymphoid Chemokines ▿ †

    PubMed Central

    Giusti, Pablo; Urban, Britta C.; Frascaroli, Giada; Albrecht, Letusa; Tinti, Anna; Troye-Blomberg, Marita; Varani, Stefania

    2011-01-01

    Acute and chronic Plasmodium falciparum infections alter the immune competence of the host possibly through changes in dendritic cell (DC) functionality. DCs are the most potent activators of T cells, and migration is integral to their function. Mature DCs express lymphoid chemokine receptors (CCRs), expression of which enables them to migrate to the lymph nodes, where they encounter naïve T cells. The present study aimed to investigate the impact of the synthetic analog to malaria parasite pigment hemozoin, i.e., β-hematin, or infected erythrocytes (iRBCs) on the activation status of human monocyte-derived DCs and on their expression of CCRs. Human monocyte-derived DCs partially matured upon incubation with β-hematin as indicated by an increased expression of CD80 and CD83. Both β-hematin and iRBCs provoked the release of proinflammatory and anti-inflammatory cytokines, such as interleukin-6 (IL-6), IL-10, and tumor necrosis factor alpha, but not IL-12, and induced upregulation of the lymphoid chemokine receptor CXCR4, which was coupled to an increased migration to lymphoid ligands. Taken together, these results suggest that the partial and transient maturation of human myeloid DCs upon stimulation with malaria parasite-derived products and the increased IL-10 but lack of IL-12 secretion may lead to suboptimal activation of T cells. This may in turn lead to impaired adaptive immune responses and therefore insufficient clearance of the parasites. PMID:21464084

  19. Spleen enlargement and genetic diversity of Plasmodium falciparum infection in two ethnic groups with different malaria susceptibility in Mali, West Africa.

    PubMed

    Bereczky, S; Dolo, A; Maiga, B; Hayano, M; Granath, F; Montgomery, S M; Daou, M; Arama, C; Troye-Blomberg, M; Doumbo, O K; Färnert, A

    2006-03-01

    The high resistance to malaria in the nomadic Fulani population needs further understanding. The ability to cope with multiclonal Plasmodium falciparum infections was assessed in a cross-sectional survey in the Fulani and the Dogon, their sympatric ethnic group in Mali. The Fulani had lower parasite prevalence and densities and more prominent spleen enlargement. Spleen rates in children aged 2-9 years were 75% in the Fulani and 44% in the Dogon (P<0.001). There was no difference in number of P. falciparum genotypes, defined by merozoite surface protein 2 polymorphism, with mean values of 2.25 and 2.11 (P=0.503) in the Dogon and Fulani, respectively. Spleen rate increased with parasite prevalence, density and number of co-infecting clones in asymptomatic Dogon. Moreover, splenomegaly was increased in individuals with clinical malaria in the Dogon, odds ratio 3.67 (95% CI 1.65-8.15, P=0.003), but not found in the Fulani, 1.36 (95% CI 0.53-3.48, P=0.633). The more susceptible Dogon population thus appear to respond with pronounced spleen enlargement to asymptomatic multiclonal infections and acute disease whereas the Fulani have generally enlarged spleens already functional for protection. The results emphasize the importance of spleen function in protective immunity to the polymorphic malaria parasite.

  20. The Prevalence of α-Thalassemia and Its Relation to Plasmodium falciparum Infection in Patients Presenting to Clinics in Two Distinct Ecological Zones in Ghana.

    PubMed

    Ghartey-Kwansah, George; Boampong, Johnson N; Aboagye, Benjamin; Afoakwah, Richmond; Ameyaw, Elvis O; Quashie, Neils B

    2016-01-01

    Thalassemia and sickle cell disease constitute the most monogenic hemoglobin (Hb) disorders worldwide. Clinical symptoms of α(+)-thalassemia (α(+)-thal) are related to inadequate Hb production and accumulation of β- and/or γ-globin subunits. The association of thalassemia with malaria remains contentious, though from its distribution it appears to have offered some protection against the disease. Data on the prevalence of thalassemia in Ghana and its link with malaria is scanty and restricted. It was an objective of this cross-sectional study to determine the prevalence of thalassemia in areas representing two of Ghana's distinct ecological zones. The relationship between thalassemia and Plasmodium falciparium (P. falciparum) infection was also ascertained. Overall, 277 patients presenting to health facilities in the study areas were recruited to participate. Tests were carried out to determine the presence of α(+)-thal, sickle cell and malaria parasites in the blood samples of participants. The outcome of this study showed an α(+)-thal frequency of 19.9% for heterozygotes (-α/αα) and 6.8% for homozygotes (-α/-α). Plasmodium falciparum was detected in 17.7% of the overall study population and 14.9% in those with α(+)-thal. No association was observed between those with α(+)-thal and the study sites (p > 0.05). A test of the Hardy-Weinberg law yielded no significant difference (p < 0.001). Findings from this study suggest a modest distribution of α(+)-thal in Ghana with no bias to the ecological zones. Although the prevalence and parasite density were relatively low in those with the disorder, no association was found between them.

  1. Interaction between Endothelial Protein C Receptor and Intercellular Adhesion Molecule 1 to Mediate Binding of Plasmodium falciparum-Infected Erythrocytes to Endothelial Cells

    PubMed Central

    Avril, Marion; Bernabeu, Maria; Benjamin, Maxwell; Brazier, Andrew Jay

    2016-01-01

    ABSTRACT Intercellular adhesion molecule 1 (ICAM-1) and the endothelial protein C receptor (EPCR) are candidate receptors for the deadly complication cerebral malaria. However, it remains unclear if Plasmodium falciparum parasites with dual binding specificity are involved in cytoadhesion or different parasite subpopulations bind in brain microvessels. Here, we investigated this issue by studying different subtypes of ICAM-1-binding parasite lines. We show that two parasite lines expressing domain cassette 13 (DC13) of the P. falciparum erythrocyte membrane protein 1 (PfEMP1) family have dual binding specificity for EPCR and ICAM-1 and further mapped ICAM-1 binding to the first DBLβ domain following the PfEMP1 head structure in both proteins. As PfEMP1 head structures have diverged between group A (EPCR binders) and groups B and C (CD36 binders), we also investigated how ICAM-1-binding parasites with different coreceptor binding traits influence P. falciparum-infected erythrocyte binding to endothelial cells. Whereas levels of binding to tumor necrosis factor alpha (TNF-α)-stimulated endothelial cells from the lung and brain by all ICAM-1-binding parasite lines increased, group A (EPCR and ICAM-1) was less dependent than group B (CD36 and ICAM-1) on ICAM-1 upregulation. Furthermore, both group A DC13 parasite lines had higher binding levels to brain endothelial cells (a microvascular niche with limited CD36 expression). This study shows that ICAM-1 is a coreceptor for a subset of EPCR-binding parasites and provides the first evidence of how EPCR and ICAM-1 interact to mediate parasite binding to both resting and TNF-α-activated primary brain and lung endothelial cells. PMID:27406562

  2. Recruitment of Factor H as a Novel Complement Evasion Strategy for Blood-Stage Plasmodium falciparum Infection.

    PubMed

    Kennedy, Alexander T; Schmidt, Christoph Q; Thompson, Jennifer K; Weiss, Greta E; Taechalertpaisarn, Tana; Gilson, Paul R; Barlow, Paul N; Crabb, Brendan S; Cowman, Alan F; Tham, Wai-Hong

    2016-02-01

    The human complement system is the frontline defense mechanism against invading pathogens. The coexistence of humans and microbes throughout evolution has produced ingenious molecular mechanisms by which microorganisms escape complement attack. A common evasion strategy used by diverse pathogens is the hijacking of soluble human complement regulators to their surfaces to afford protection from complement activation. One such host regulator is factor H (FH), which acts as a negative regulator of complement to protect host tissues from aberrant complement activation. In this report, we show that Plasmodium falciparum merozoites, the invasive form of the malaria parasites, actively recruit FH and its alternative spliced form FH-like protein 1 when exposed to human serum. We have mapped the binding site in FH that recognizes merozoites and identified Pf92, a member of the six-cysteine family of Plasmodium surface proteins, as its direct interaction partner. When bound to merozoites, FH retains cofactor activity, a key function that allows it to downregulate the alternative pathway of complement. In P. falciparum parasites that lack Pf92, we observed changes in the pattern of C3b cleavage that are consistent with decreased regulation of complement activation. These results also show that recruitment of FH affords P. falciparum merozoites protection from complement-mediated lysis. Our study provides new insights on mechanisms of immune evasion of malaria parasites and highlights the important function of surface coat proteins in the interplay between complement regulation and successful infection of the host.

  3. Surface antigen expression on Plasmodium falciparum-infected erythrocytes is modified in alpha- and beta-thalassemia

    PubMed Central

    1991-01-01

    In an attempt to determine the mechanism whereby thalassemia in its milder forms may protect against malaria, we have examined the expression of neoantigen at the surface of Plasmodium falciparum- parasitized thalassemic red cells. Neoantigen expression was estimated by measurement of antibody bound after incubation in serum from adults living in a malaria-endemic area, using a quantitative radiometric antiglobulin assay. We found that P. falciparum-parasitized alpha- and beta-thalassemic red cells bind greater levels of antibody from endemic serum than controls: mean binding ratios (+/- SE), respectively, for alpha- and beta-thalassemia compared with controls were 1.69 +/- 0.12 and 1.23 +/- 0.06 on a cell for cell basis, and 1.97 +/- 0.11 and 1.47 +/- 0.08 after a correction for surface area differences. Binding of antibody increased exponentially during parasite maturation. In addition, we found a small but significant degree of binding of naturally occurring antibody to parasitized red cells, the extent of which was also greater in thalassemia. The apparent protective effect of thalassemia against malaria may be related to enhanced immune recognition and hence clearance of parasitized erythrocytes. PMID:2007853

  4. Induction of pro-inflammatory response of the placental trophoblast by Plasmodium falciparum infected erythrocytes and TNF

    PubMed Central

    2013-01-01

    Background Plasmodium falciparum placental malaria is characterized by the sequestration of infected erythrocytes (IEs) in the placental intervillous space via adherence to chondroitin sulphate A (CSA), production of inflammatory molecules, and leukocytes infiltration. Previous reports suggest that the syncytiotrophoblast (ST) immunologically responds to IEs contact. This study explores the inflammatory response induced in BeWo cells by adherence of IEs and TNFstimulation. Methods A non-syncitialized BeWo cells (trophoblast model) were used to evaluate its response to CSA-adherents IEs (FCB1csa, FCB2csa, FCR3csa, 3D7csa) and TNF stimulation. Expression of membrane ICAM-1 (mICAM-1) receptor in BeWo cells was quantified by flow cytometry and the IL-8, IL-6 and soluble ICAM-1 (sICAM-1) concentrations were quantified by enzyme-linked immunosorbentassay (ELISA) in BeWo stimulated supernatants. Results BeWo cells stimulated with TNF and CSA-adherents IEs of FCB1csa and 3D7csa (strains with higher adhesion) increase the expression of ICAM-1 on the surface of cells and the secretion of immune factors IL-8, IL-6 and sICAM-1. This inflammatory response appears to be related to the level of adherence of IEs because less adherent strains do not induce significant changes. Conclusions It was found that BeWo cells responds to CSA-IEs and to TNF favouring a placental pro-inflammatory environment, evidenced by increases in the expression of membrane mICAM-1 and release of soluble ICAM-1, as well as the IL-8 and IL-6 secretion. The expression of ICAM-1 in BeWo cells might be associated to an increase in leukocyte adhesion to the trophoblast barrier, promoting greater inflammation, while the sICAM-1 release could be a protection mechanism activated by trophoblastic cells, in order to regulate the local inflammatory response. PMID:24237643

  5. Plasmodium falciparum-Infected Erythrocyte Knob Density Is Linked to the PfEMP1 Variant Expressed

    PubMed Central

    Subramani, Ramesh; Quadt, Katharina; Jeppesen, Anine E.; Hempel, Casper; Petersen, Jens Emil Vang; Hassenkam, Tue; Hviid, Lars

    2015-01-01

    ABSTRACT Members of the clonally variant Plasmodium falciparum erythrocyte membrane protein 1 (PfEMP1) family mediate adhesion of infected erythrocytes (IEs) to vascular receptors. PfEMP1 expression is normally confined to nanoscale knob protrusions on the IE surface membrane. To investigate the relationship between the densities of these IE surface knobs and the PfEMP1 variant expressed, we used specific antibody panning to generate three sublines of the P. falciparum clone IT4, which expresses the PfEMP1 variants IT4VAR04, IT4VAR32b, and IT4VAR60. The knob density in each subline was then determined by atomic force microscopy (AFM) and scanning electron microscopy (SEM) and compared to PfEMP1 and knob-associated histidine-rich protein (KAHRP) expression. Selection for uniform expression of IT4VAR04 produced little change in knob density, compared to unselected IEs. In contrast, selection for IT4VAR32b expression increased knob density approximately 3-fold, whereas IEs selected for IT4VAR60 expression were essentially knobless. When IT4VAR60+ IEs were subsequently selected to express IT4VAR04 or IT4VAR32b, they again displayed low and high knob densities, respectively. All sublines expressed KAHRP regardless of the PfEMP1 expressed. Our study documents for the first time that knob density is related to the PfEMP1 variant expressed. This may reflect topological requirements to ensure optimal adhesive properties of the IEs. PMID:26443460

  6. A country-wide malaria survey in Mozambique. I. Plasmodium falciparum infection in children in different epidemiological settings

    PubMed Central

    Mabunda, Samuel; Casimiro, Sónia; Quinto, Llorenç; Alonso, Pedro

    2008-01-01

    Background Across tropical Africa the bulk of malaria-related morbidity and mortality is particularly high during childhood. Classical malariometric surveys have relied on assessing malaria infection prevalence. The last comprehensive evaluation of the malaria situation in Mozambique was carried out during the 1950s. This study aims to characterize the malaria transmission intensities and to estimate the disease burden that may help guide control programme. Methods Between February 2002 and April 2003, a house-to-house survey, was carried out in 24 districts randomly selected. A total of 8,816 children aged below 10 years old were enrolled. Finger prick and blood collection were performed to prepare thick and thin films for malaria parasite species identification, density and haemoglobin concentration. Axillary temperature was also measured. Prevalence of infection, parasite density and anaemia were estimated for age groups category in each region/stratum. Comparisons between proportions were made using Chi-square test or Fisher exact. Relationship between age groups, region/stratum and parasite prevalence, density was determined using linear regression. All survey mean estimations were adjusted for sampling weights, clustering and stratification. Results Malaria parasite prevalence was 58.9% (5.190/8.816), the majority of blood smears 52.4% (4,616/8,816) were due to Plasmodium falciparum and geometric mean parasite density was 1,211 parasites/μl (95% CI, 1,141 – 1.286). Gametocytes prevalence, only for P. falciparum was 5.6% (518/8,816). The burden was highest in the northern regions and in the coastal stratum. Parasite infection and geometric mean parasite density peaked during the second year of life and thereafter decreased with increasing age. Mean haemoglobin concentrations was 9.9 g/dl (95% CI 9.5 – 10.2). Anaemia prevalence was 69.8% (6.257/8.816) and among anaemic children 11.5% (743/6.257) were severely anaemic. Anaemia rose dramatically during the

  7. Impact of mosquito bites on asexual parasite density and gametocyte prevalence in asymptomatic chronic Plasmodium falciparum infections and correlation with IgE and IgG titers.

    PubMed

    Lawaly, Ramatoulaye; Konate, Lassana; Marrama, Laurence; Dia, Ibrahima; Diallo, Diawo; Diène Sarr, Fatoumata; Schneider, Bradley S; Casademont, Isabelle; Diallo, Mawlouth; Brey, Paul T; Sakuntabhai, Anavaj; Mecheri, Salah; Paul, Richard

    2012-06-01

    An immunomodulatory role of arthropod saliva has been well documented, but evidence for an effect on Plasmodium sp. infectiousness remains controversial. Mosquito saliva may orient the immune response toward a Th2 profile, thereby priming a Th2 response against subsequent antigens, including Plasmodium. Orientation toward a Th1 versus a Th2 profile promotes IgG and IgE proliferation, respectively, where the former is crucial for the development of an efficient antiparasite immune response. Here we assessed the direct effect of mosquito bites on the density of Plasmodium falciparum asexual parasites and the prevalence of gametocytes in chronic, asymptomatic infections in a longitudinal cohort study of seasonal transmission. We additionally correlated these parasitological measures with IgE and IgG antiparasite and anti-salivary gland extract titers. The mosquito biting density was positively correlated with the asexual parasite density but not asexual parasite prevalence and was negatively correlated with gametocyte prevalence. Individual anti-salivary gland IgE titers were also negatively correlated with gametocyte carriage and were strongly positively correlated with antiparasite IgE titers, consistent with the hypothesis that mosquito bites predispose individuals to develop an IgE antiparasite response. We provide evidence that mosquito bites have an impact on asymptomatic infections and differentially so for the production of asexual and sexual parasites. An increased research focus on the immunological impact of mosquito bites during asymptomatic infections is warranted, to establish whether strategies targeting the immune response to saliva can reduce the duration of infection and the onward transmission of the parasite.

  8. Rosetting Plasmodium falciparum-infected erythrocytes bind to human brain microvascular endothelial cells in vitro, demonstrating a dual adhesion phenotype mediated by distinct P. falciparum erythrocyte membrane protein 1 domains.

    PubMed

    Adams, Yvonne; Kuhnrae, Pongsak; Higgins, Matthew K; Ghumra, Ashfaq; Rowe, J Alexandra

    2014-03-01

    Adhesion interactions between Plasmodium falciparum-infected erythrocytes (IE) and human cells underlie the pathology of severe malaria. IE cytoadhere to microvascular endothelium or form rosettes with uninfected erythrocytes to survive in vivo by sequestering IE in the microvasculature and avoiding splenic clearance mechanisms. Both rosetting and cytoadherence are mediated by the parasite-derived IE surface protein family Plasmodium falciparum erythrocyte membrane protein 1 (PfEMP1). Rosetting and cytoadherence have been widely studied as separate entities; however, the ability of rosetting P. falciparum strains to cytoadhere has received little attention. Here, we show that IE of the IT/R29 strain expressing a rosette-mediating PfEMP1 variant (IT4var09) cytoadhere in vitro to a human brain microvascular endothelial cell line (HBEC-5i). Cytoadherence was inhibited by heparin and by treatment of HBEC-5i with heparinase III, suggesting that the endothelial receptors for IE binding are heparan sulfate proteoglycans. Antibodies to the N-terminal regions of the IT4var09 PfEMP1 variant (NTS-DBL1α and DBL2γ domains) specifically inhibited and reversed cytoadherence down to low concentrations (<10 μg/ml of total IgG). Surface plasmon resonance experiments showed that the NTS-DBLα and DBL2γ domains bind strongly to heparin, with half-maximal binding at a concentration of ∼0.5 μM in both cases. Therefore, cytoadherence of IT/R29 IE is distinct from rosetting, which is primarily mediated by NTS-DBL1α interactions with complement receptor 1. These data show that IT4var09-expressing parasites are capable of dual interactions with both endothelial cells and uninfected erythrocytes via distinct receptor-ligand interactions.

  9. Small, clonally variant antigens expressed on the surface of the Plasmodium falciparum-infected erythrocyte are encoded by the rif gene family and are the target of human immune responses.

    PubMed

    Fernandez, V; Hommel, M; Chen, Q; Hagblom, P; Wahlgren, M

    1999-11-15

    Disease severity in Plasmodium falciparum infections is a direct consequence of the parasite's efficient evasion of the defense mechanisms of the human host. To date, one parasite-derived molecule, the antigenically variant adhesin P. falciparum erythrocyte membrane protein 1 (PfEMP1), is known to be transported to the infected erythrocyte (pRBC) surface, where it mediates binding to different host receptors. Here we report that multiple additional proteins are expressed by the parasite at the pRBC surface, including a large cluster of clonally variant antigens of 30-45 kD. We have found these antigens to be identical to the rifins, predicted polypeptides encoded by the rif multigene family. These parasite products, formerly called rosettins after their identification in rosetting parasites, are prominently expressed by fresh isolates of P. falciparum. Rifins are immunogenic in natural infections and strain-specifically recognized by human immune sera in immunoprecipitation of surface-labeled pRBC extracts. Furthermore, human immune sera agglutinate pRBCs digested with trypsin at conditions such that radioiodinated PfEMP1 polypeptides are not detected but rifins are detected, suggesting the presence of epitopes in rifins targeted by agglutinating antibodies. When analyzed by two-dimensional electrophoresis, the rifins resolved into several isoforms in the pI range of 5.5-6.5, indicating molecular microheterogeneity, an additional potential novel source of antigenic diversity in P. falciparum. Prominent polypeptides of 20, 22, 76-80, 140, and 170 kD were also detected on the surfaces of pRBCs bearing in vitro-propagated or field-isolated parasites. In this report, we describe the rifins, the second family of clonally variant antigens known to be displayed by P. falciparum on the surface of the infected erythrocyte.

  10. Platelet-mediated clumping of Plasmodium falciparum-infected erythrocytes is a common adhesive phenotype and is associated with severe malaria

    PubMed Central

    Pain, Arnab; Ferguson, David J. P.; Kai, Oscar; Urban, Britta C.; Lowe, Brett; Marsh, Kevin; Roberts, David J.

    2001-01-01

    Sequestration of malaria-infected erythrocytes in the peripheral circulation has been associated with the virulence of Plasmodium falciparum. Defining the adhesive phenotypes of infected erythrocytes may therefore help us to understand how severe disease is caused and how to prevent or treat it. We have previously shown that malaria-infected erythrocytes may form apparent autoagglutinates of infected erythrocytes. Here we show that such autoagglutination of a laboratory line of P. falciparum is mediated by platelets and that the formation of clumps of infected erythrocytes and platelets requires expression of the platelet surface glycoprotein CD36. Platelet-dependent clumping is a distinct adhesive phenotype, expressed by some but not all CD36-binding parasite lines, and is common in field isolates of P. falciparum. Finally, we have established that platelet-mediated clumping is strongly associated with severe malaria. Precise definition of the molecular basis of this intriguing adhesive phenotype may help to elucidate the complex pathophysiology of malaria. PMID:11172032

  11. A PfRH5-based vaccine is efficacious against heterologous strain blood-stage Plasmodium falciparum infection in aotus monkeys.

    PubMed

    Douglas, Alexander D; Baldeviano, G Christian; Lucas, Carmen M; Lugo-Roman, Luis A; Crosnier, Cécile; Bartholdson, S Josefin; Diouf, Ababacar; Miura, Kazutoyo; Lambert, Lynn E; Ventocilla, Julio A; Leiva, Karina P; Milne, Kathryn H; Illingworth, Joseph J; Spencer, Alexandra J; Hjerrild, Kathryn A; Alanine, Daniel G W; Turner, Alison V; Moorhead, Jeromy T; Edgel, Kimberly A; Wu, Yimin; Long, Carole A; Wright, Gavin J; Lescano, Andrés G; Draper, Simon J

    2015-01-14

    Antigenic diversity has posed a critical barrier to vaccine development against the pathogenic blood-stage infection of the human malaria parasite Plasmodium falciparum. To date, only strain-specific protection has been reported by trials of such vaccines in nonhuman primates. We recently showed that P. falciparum reticulocyte binding protein homolog 5 (PfRH5), a merozoite adhesin required for erythrocyte invasion, is highly susceptible to vaccine-inducible strain-transcending parasite-neutralizing antibody. In vivo efficacy of PfRH5-based vaccines has not previously been evaluated. Here, we demonstrate that PfRH5-based vaccines can protect Aotus monkeys against a virulent vaccine-heterologous P. falciparum challenge and show that such protection can be achieved by a human-compatible vaccine formulation. Protection was associated with anti-PfRH5 antibody concentration and in vitro parasite-neutralizing activity, supporting the use of this in vitro assay to predict the in vivo efficacy of future vaccine candidates. These data suggest that PfRH5-based vaccines have potential to achieve strain-transcending efficacy in humans.

  12. A PfRH5-Based Vaccine Is Efficacious against Heterologous Strain Blood-Stage Plasmodium falciparum Infection in Aotus Monkeys

    PubMed Central

    Douglas, Alexander D.; Baldeviano, G. Christian; Lucas, Carmen M.; Lugo-Roman, Luis A.; Crosnier, Cécile; Bartholdson, S. Josefin; Diouf, Ababacar; Miura, Kazutoyo; Lambert, Lynn E.; Ventocilla, Julio A.; Leiva, Karina P.; Milne, Kathryn H.; Illingworth, Joseph J.; Spencer, Alexandra J.; Hjerrild, Kathryn A.; Alanine, Daniel G.W.; Turner, Alison V.; Moorhead, Jeromy T.; Edgel, Kimberly A.; Wu, Yimin; Long, Carole A.; Wright, Gavin J.; Lescano, Andrés G.; Draper, Simon J.

    2015-01-01

    Summary Antigenic diversity has posed a critical barrier to vaccine development against the pathogenic blood-stage infection of the human malaria parasite Plasmodium falciparum. To date, only strain-specific protection has been reported by trials of such vaccines in nonhuman primates. We recently showed that P. falciparum reticulocyte binding protein homolog 5 (PfRH5), a merozoite adhesin required for erythrocyte invasion, is highly susceptible to vaccine-inducible strain-transcending parasite-neutralizing antibody. In vivo efficacy of PfRH5-based vaccines has not previously been evaluated. Here, we demonstrate that PfRH5-based vaccines can protect Aotus monkeys against a virulent vaccine-heterologous P. falciparum challenge and show that such protection can be achieved by a human-compatible vaccine formulation. Protection was associated with anti-PfRH5 antibody concentration and in vitro parasite-neutralizing activity, supporting the use of this in vitro assay to predict the in vivo efficacy of future vaccine candidates. These data suggest that PfRH5-based vaccines have potential to achieve strain-transcending efficacy in humans. PMID:25590760

  13. Plasmodium falciparum Infection of Human Volunteers Activates Monocytes and CD16+ Dendritic Cells and Induces Upregulation of CD16 and CD1c Expression

    PubMed Central

    Teirlinck, Anne C.; Roestenberg, Meta; Bijker, Else M.; Hoffman, Stephen L.

    2015-01-01

    Antigen-presenting cells (APCs) are key players in the induction and regulation of immune responses. In Plasmodium falciparum malaria, determination of which cells and pathways are activated in the network of APCs remains elusive. We therefore investigated the effects of a controlled human malaria infection in healthy, malaria-naive volunteers on the subset composition and activation status of dendritic cells (DCs) and monocytes. While subsets of monocytes increased in frequency during blood-stage infection, DC frequencies remained largely stable. Activation markers classically associated with peptide presentation to and priming of αβT cells, HLA-DR and CD86, were upregulated in monocytes and inflammatory CD16 myeloid DCs (mDCs) but not in the classical CD1c, BDCA2, or BDCA3 DC subsets. In addition, these activated APC subsets showed increased expression of CD1c, which is involved in glycolipid antigen presentation, and of the immune complex binding Fcγ receptor III (CD16). Our data show that P. falciparum asexual parasites do not activate classical DC subsets but instead activate mainly monocytes and inflammatory CD16 mDCs and appear to prime alternative activation pathways via induction of CD16 and/or CD1c. Changes in expression of these surface molecules might increase antigen capture and enhance glycolipid antigen presentation in addition to the classical major histocompatibility complex class II (MHC-II) peptide presentation and thereby contribute to the initiation of T-cell responses in malaria. (This study has been registered at Clinicaltrials.gov under registration no. NCT01086917.) PMID:26169270

  14. Pharmacokinetics of co-formulated mefloquine and artesunate in pregnant and non-pregnant women with uncomplicated Plasmodium falciparum infection in Burkina Faso

    PubMed Central

    Valea, Innocent; Tinto, Halidou; Traore/Coulibaly, Maminata; Toe, Laeticia C.; Lindegardh, Niklas; Tarning, Joel; Van Geertruyden, Jean-Pierre; D'Alessandro, Umberto; Davies, Geraint R.; Ward, Stephen A.

    2014-01-01

    Objectives Mefloquine/artesunate has recently been developed as a fixed-dose combination, providing a promising rescue/alternative treatment for malaria during pregnancy. However, limited data are available on the effect of pregnancy on its pharmacokinetic properties. This study was conducted to assess the pharmacokinetic properties of mefloquine/carboxymefloquine and artesunate/dihydroartemisinin in pregnant and non-pregnant women with uncomplicated malaria. Methods Twenty-four women in their second and third trimesters of pregnancy and 24 paired non-pregnant women were enrolled. All patients were treated for uncomplicated Plasmodium falciparum malaria with a standard fixed-dose combination of oral mefloquine and artesunate one daily over 3 days. Frequent blood samples were collected before treatment and at scheduled times post-dose for the drug measurements and pharmacokinetic analyses. The study was registered at www.clinicaltrials.gov (identifier: NCT00701961). Results The total median exposure to mefloquine and dihydroartemisinin was not significantly different between the pregnant and non-pregnant women (P > 0.05). There was a trend of higher exposure to mefloquine in the pregnant women, but this difference did not reach statistical significance (656 700 versus 542 400 h × ng/mL; P = 0.059). However, the total exposure to carboxymefloquine was 49% lower during pregnancy (735 600 versus 1 499 000 h × ng/mL; P < 0.001) and the total drug exposure to artesunate was 42% higher during pregnancy (89.0 versus 62.9 h × ng/mL; P = 0.039) compared with non-pregnant controls. Conclusions The plasma levels of mefloquine and dihydroartemisinin appeared to be similar in both pregnant and non-pregnant women, but there were significant differences in carboxymefloquine and artesunate exposure. The data presented here do not warrant a dose adjustment in pregnant patients, but an extensive analysis of the data could provide a better

  15. The Effect of Insecticide Treated Nets (ITNs) on Plasmodium falciparum Infection in Rural and Semi-Urban Communities in the South West Region of Cameroon

    PubMed Central

    Apinjoh, Tobias O.; Anchang-Kimbi, Judith K.; Mugri, Regina N.; Tangoh, Delphine A.; Nyingchu, Robert V.; Chi, Hanesh F.; Tata, Rolland B.; Njumkeng, Charles; Njua-Yafi, Clarisse; Achidi, Eric A.

    2015-01-01

    Insecticide Treated Nets (ITNs) have been shown to reduce morbidity and mortality, but coverage and proper utilization continues to be moderate in many parts of sub-Saharan Africa. The gains made through a nationwide free distribution were explored as well as the effect on malaria prevalence in semi-urban and rural communities in south western Cameroon. A cross sectional survey was conducted between August and December 2013. Information on net possession, status and use were collected using a structured questionnaire while malaria parasitaemia was determined on Giemsa-stained blood smears by light microscopy. ITN ownership increased from 41.9% to 68.1% following the free distribution campaign, with 58.3% (466/799) reportedly sleeping under the net. ITN ownership was lower in rural settings (adjusted OR = 1.93, 95%CI = 1.36–2.74, p<0.001) and at lower altitude (adjusted OR = 1.79, 95%CI = 1.22–2.62, p = 0.003) compared to semi-urban settings and intermediate altitude respectively. Conversely, ITN usage was higher in semi-urban settings (p = 0.002) and at intermediate altitude (p = 0.002) compared with rural localities and low altitude. Malaria parasitaemia prevalence was higher in rural (adjusted OR = 1.63, 95%CI = 1.07–2.49) compared to semi-urban settings and in those below 15 years compared to those 15 years and above. Overall, participants who did not sleep under ITN were more susceptible to malaria parasitaemia (adjusted OR = 1.70, 95%CI = 1.14–2.54, p = 0.009). Despite the free distribution campaign, ITN ownership and usage, though improved, is still low. As children who reside in rural settings have greater disease burden (parasitemia) than children in semi-urban settings, the potential gains on both reducing inequities in ITN possession as well as disease burden might be substantial if equitable distribution strategies are adopted. PMID:25714837

  16. Preserved dendritic cell HLA-DR expression and reduced regulatory T cell activation in asymptomatic Plasmodium falciparum and P. vivax infection.

    PubMed

    Kho, Steven; Marfurt, Jutta; Noviyanti, Rintis; Kusuma, Andreas; Piera, Kim A; Burdam, Faustina H; Kenangalem, Enny; Lampah, Daniel A; Engwerda, Christian R; Poespoprodjo, Jeanne R; Price, Ric N; Anstey, Nicholas M; Minigo, Gabriela; Woodberry, Tonia

    2015-08-01

    Clinical illness with Plasmodium falciparum or Plasmodium vivax compromises the function of dendritic cells (DC) and expands regulatory T (Treg) cells. Individuals with asymptomatic parasitemia have clinical immunity, restricting parasite expansion and preventing clinical disease. The role of DC and Treg cells during asymptomatic Plasmodium infection is unclear. During a cross-sectional household survey in Papua, Indonesia, we examined the number and activation of blood plasmacytoid DC (pDC), CD141(+), and CD1c(+) myeloid DC (mDC) subsets and Treg cells using flow cytometry in 168 afebrile children (of whom 15 had P. falciparum and 36 had P. vivax infections) and 162 afebrile adults (of whom 20 had P. falciparum and 20 had P. vivax infections), alongside samples from 16 patients hospitalized with uncomplicated malaria. Unlike DC from malaria patients, DC from children and adults with asymptomatic, microscopy-positive P. vivax or P. falciparum infection increased or retained HLA-DR expression. Treg cells in asymptomatic adults and children exhibited reduced activation, suggesting increased immune responsiveness. The pDC and mDC subsets varied according to clinical immunity (asymptomatic or symptomatic Plasmodium infection) and, in asymptomatic infection, according to host age and parasite species. In conclusion, active control of asymptomatic infection was associated with and likely contingent upon functional DC and reduced Treg cell activation.

  17. Safety, immunogenicity and protective effect of the SPf66 malaria synthetic vaccine against Plasmodium falciparum infection in a randomized double-blind placebo-controlled field trial in an endemic area of Ecuador.

    PubMed

    Sempértegui, F; Estrella, B; Moscoso, J; Piedrahita, L; Hernández, D; Gaybor, J; Naranjo, P; Mancero, O; Arias, S; Bernal, R

    1994-03-01

    A total of 537 subjects were randomized to receive either SPf66 malaria vaccine against Plasmodium falciparum or placebo in three doses (days 0, 30 and 180). Subjects completing the course of vaccination (230 in the vaccine and 238 in the placebo group) were followed up for a further 12 months. Case detection surveillance was implemented by parasitological cross-sectional surveys every 2 months and by monthly household visits to each participant. Symptomatic subjects were also diagnosed in a local health centre. Minor local side-effects were observed mainly after the second dose in about 19% of the vaccinated subjects and in 3.7% of the placebo group. Thirty days after the third dose the prevalence of anti-SPf66 antibodies was 57% in the vaccine and 8.8% in the placebo groups. The prevaccination prevalence of antibodies measured by indirect immunofluorescence assay increased with age and seemed to be inversely related to anti-SPf66 antibody production. Immune response to SPf66 was independent of age. Vaccine efficacy was calculated based on person-time of exposure. The protective effect considering any malaria episode was 66.8% (95% confidence interval = -2.7-89.3%) and considering only one episode per individual was 60.2% (95% confidence interval = -26-87.5%).

  18. Soil-transmitted helminths and Plasmodium falciparum malaria: epidemiology, clinical manifestations, and the role of nitric oxide in malaria and geohelminth co-infection. Do worms have a protective role in P. falciparum infection?

    PubMed

    Basavaraju, Sridhar V; Schantz, Peter

    2006-12-01

    Malaria and intestinal helminths are sources of significant morbidity worldwide. Given the nature of shared endemicity, these diseases often co-exist in the same populations. Therefore, much attention is now being given to the interaction between helminths and Plasmodium in the situation of co-infection. Existing evidence is consistent with the hypothesis that helminths are associated with continued and possibly increased incidence of malaria infection. However, data from some recent clinical fieldwork suggest protection from cerebral malaria in the setting of helminth co-infection. Nitric oxide, coupled with the immunoglobulin E (IgE) receptor, CD23, appears to be a crucial factor in preventing the development of cerebral malaria, thus improving chances for the survival of both host and parasite. In this work, we review literature on the subject of helminth and malaria co-infection, and offer a theoretical explanation of the helminth modulation of clinical malaria. In doing so, we advocate further research on this subject and also the need for a dual approach in global disease control intervention, which simultaneously targets both malaria and geohelminth infection.

  19. Spatial Effects on the Multiplicity of Plasmodium falciparum Infections

    PubMed Central

    Karl, Stephan; White, Michael T.; Milne, George J.; Gurarie, David; Hay, Simon I.; Barry, Alyssa E.; Felger, Ingrid; Mueller, Ivo

    2016-01-01

    As malaria is being pushed back on many frontiers and global case numbers are declining, accurate measurement and prediction of transmission becomes increasingly difficult. Low transmission settings are characterised by high levels of spatial heterogeneity, which stands in stark contrast to the widely used assumption of spatially homogeneous transmission used in mathematical transmission models for malaria. In the present study an individual-based mathematical malaria transmission model that incorporates multiple parasite clones, variable human exposure and duration of infection, limited mosquito flight distance and most importantly geographically heterogeneous human and mosquito population densities was used to illustrate the differences between homogeneous and heterogeneous transmission assumptions when aiming to predict surrogate indicators of transmission intensity such as population parasite prevalence or multiplicity of infection (MOI). In traditionally highly malaria endemic regions where most of the population harbours malaria parasites, humans are often infected with multiple parasite clones. However, studies have shown also in areas with low overall parasite prevalence, infection with multiple parasite clones is a common occurrence. Mathematical models assuming homogeneous transmission between humans and mosquitoes cannot explain these observations. Heterogeneity of transmission can arise from many factors including acquired immunity, body size and occupational exposure. In this study, we show that spatial heterogeneity has a profound effect on predictions of MOI and parasite prevalence. We illustrate, that models assuming homogeneous transmission underestimate average MOI in low transmission settings when compared to field data and that spatially heterogeneous models predict stable transmission at much lower overall parasite prevalence. Therefore it is very important that models used to guide malaria surveillance and control strategies in low transmission and elimination settings take into account the spatial features of the specific target area, including human and mosquito vector distribution. PMID:27711149

  20. Clonal outbreak of Plasmodium falciparum infection in eastern Panama.

    PubMed

    Obaldia, Nicanor; Baro, Nicholas K; Calzada, Jose E; Santamaria, Ana M; Daniels, Rachel; Wong, Wesley; Chang, Hsiao-Han; Hamilton, Elizabeth J; Arevalo-Herrera, Myriam; Herrera, Socrates; Wirth, Dyann F; Hartl, Daniel L; Marti, Matthias; Volkman, Sarah K

    2015-04-01

    Identifying the source of resurgent parasites is paramount to a strategic, successful intervention for malaria elimination. Although the malaria incidence in Panama is low, a recent outbreak resulted in a 6-fold increase in reported cases. We hypothesized that parasites sampled from this epidemic might be related and exhibit a clonal population structure. We tested the genetic relatedness of parasites, using informative single-nucleotide polymorphisms and drug resistance loci. We found that parasites were clustered into 3 clonal subpopulations and were related to parasites from Colombia. Two clusters of Panamanian parasites shared identical drug resistance haplotypes, and all clusters shared a chloroquine-resistance genotype matching the pfcrt haplotype of Colombian origin. Our findings suggest these resurgent parasite populations are highly clonal and that the high clonality likely resulted from epidemic expansion of imported or vestigial cases. Malaria outbreak investigations that use genetic tools can illuminate potential sources of epidemic malaria and guide strategies to prevent further resurgence in areas where malaria has been eliminated.

  1. Clonal Outbreak of Plasmodium falciparum Infection in Eastern Panama

    PubMed Central

    Obaldia, Nicanor; Baro, Nicholas K.; Calzada, Jose E.; Santamaria, Ana M.; Daniels, Rachel; Wong, Wesley; Chang, Hsiao-Han; Hamilton, Elizabeth J.; Arevalo-Herrera, Myriam; Herrera, Socrates; Wirth, Dyann F.; Hartl, Daniel L.; Marti, Matthias; Volkman, Sarah K.

    2015-01-01

    Identifying the source of resurgent parasites is paramount to a strategic, successful intervention for malaria elimination. Although the malaria incidence in Panama is low, a recent outbreak resulted in a 6-fold increase in reported cases. We hypothesized that parasites sampled from this epidemic might be related and exhibit a clonal population structure. We tested the genetic relatedness of parasites, using informative single-nucleotide polymorphisms and drug resistance loci. We found that parasites were clustered into 3 clonal subpopulations and were related to parasites from Colombia. Two clusters of Panamanian parasites shared identical drug resistance haplotypes, and all clusters shared a chloroquine-resistance genotype matching the pfcrt haplotype of Colombian origin. Our findings suggest these resurgent parasite populations are highly clonal and that the high clonality likely resulted from epidemic expansion of imported or vestigial cases. Malaria outbreak investigations that use genetic tools can illuminate potential sources of epidemic malaria and guide strategies to prevent further resurgence in areas where malaria has been eliminated. PMID:25336725

  2. Biliverdin targets enolase and eukaryotic initiation factor 2 (eIF2α) to reduce the growth of intraerythrocytic development of the malaria parasite Plasmodium falciparum

    PubMed Central

    Alves, Eduardo; Maluf, Fernando V.; Bueno, Vânia B.; Guido, Rafael V. C.; Oliva, Glaucius; Singh, Maneesh; Scarpelli, Pedro; Costa, Fahyme; Sartorello, Robson; Catalani, Luiz H.; Brady, Declan; Tewari, Rita; Garcia, Celia R. S.

    2016-01-01

    In mammals, haem degradation to biliverdin (BV) through the action of haem oxygenase (HO) is a critical step in haem metabolism. The malaria parasite converts haem into the chemically inert haemozoin to avoid toxicity. We discovered that the knock-out of HO in P. berghei is lethal; therefore, we investigated the function of biliverdin (BV) and haem in the parasite. Addition of external BV and haem to P. falciparum-infected red blood cell (RBC) cultures delays the progression of parasite development. The search for a BV molecular target within the parasites identified P. falciparum enolase (Pf enolase) as the strongest candidate. Isothermal titration calorimetry using recombinant full-length Plasmodium enolase suggested one binding site for BV. Kinetic assays revealed that BV is a non-competitive inhibitor. We employed molecular modelling studies to predict the new binding site as well as the binding mode of BV to P. falciparum enolase. Furthermore, addition of BV and haem targets the phosphorylation of Plasmodium falciparum eIF2α factor, an eukaryotic initiation factor phosphorylated by eIF2α kinases under stress conditions. We propose that BV targets enolase to reduce parasite glycolysis rates and changes the eIF2α phosphorylation pattern as a molecular mechanism for its action. PMID:26915471

  3. Immunisation against a serine protease inhibitor reduces intensity of Plasmodium berghei infection in mosquitoes.

    PubMed

    Williams, Andrew R; Zakutansky, Sara E; Miura, Kazutoyo; Dicks, Matthew D J; Churcher, Thomas S; Jewell, Kerry E; Vaughan, Aisling M; Turner, Alison V; Kapulu, Melissa C; Michel, Kristin; Long, Carole A; Sinden, Robert E; Hill, Adrian V S; Draper, Simon J; Biswas, Sumi

    2013-10-01

    The mosquito innate immune response is able to clear the majority of Plasmodium parasites. This immune clearance is controlled by a number of regulatory molecules including serine protease inhibitors (serpins). To determine whether such molecules could represent a novel target for a malaria transmission-blocking vaccine, we vaccinated mice with Anopheles gambiae serpin-2. Antibodies against Anopheles gambiae serpin-2 significantly reduced the infection of a heterologous Anopheles species (Anopheles stephensi) by Plasmodium berghei, however this effect was not observed with Plasmodium falciparum. Therefore, this approach of targeting regulatory molecules of the mosquito immune system may represent a novel approach to transmission-blocking malaria vaccines.

  4. Primaquine or other 8-aminoquinoline for reducing Plasmodium falciparum transmission

    PubMed Central

    Graves, Patricia M; Gelband, Hellen; Garner, Paul

    2015-01-01

    Background Mosquitoes become infected with Plasmodium when they ingest gametocyte-stage parasites from an infected person's blood. Plasmodium falciparum gametocytes are sensitive to the drug primaquine (PQ) and other 8-aminoquinolines (8AQ); these drugs could prevent parasite transmission from infected people to mosquitoes, and consequently reduce the incidence of malaria. However, PQ will not directly benefit the individual, and could be harmful to those with glucose-6-phosphate dehydrogenase (G6PD) deficiency. In 2010, The World Health Organization (WHO) recommended a single dose of PQ at 0.75 mg/kg, alongside treatment for P. falciparum malaria to reduce transmission in areas approaching malaria elimination. In 2013 the WHO revised this to 0.25 mg/kg due to concerns about safety. Objectives To assess whether giving PQ or an alternative 8AQ alongside treatment for P. falciparum malaria reduces malaria transmission, and to estimate the frequency of severe or haematological adverse events when PQ is given for this purpose. Search methods We searched the following databases up to 10 Feb 2014 for trials: the Cochrane Infectious Diseases Group Specialized Register; the Cochrane Central Register of Controlled Trials (CENTRAL), published in The Cochrane Library; MEDLINE; EMBASE; LILACS; metaRegister of Controlled Trials (mRCT); and the WHO trials search portal using 'malaria*', 'falciparum', and 'primaquine' as search terms. In addition, we searched conference proceedings and reference lists of included studies, and contacted researchers and organizations. Selection criteria Randomized controlled trials (RCTs) or quasi-RCTs comparing PQ (or alternative 8AQ) given as a single dose or short course alongside treatment for P. falciparum malaria with malaria treatment given without PQ/8AQ in adults or children. Data collection and analysis Two authors independently screened all abstracts, applied inclusion criteria, and extracted data. We sought evidence of an impact on

  5. Treatment uptake by individuals infected with Plasmodium falciparum in rural Gambia, West Africa.

    PubMed Central

    von Seidlein, Lorenz; Clarke, Sian; Alexander, Neâl; Manneh, Fandingding; Doherty, Tom; Pinder, Margaret; Walraven, Gijs; Greenwood, Brian

    2002-01-01

    OBJECTIVE: To find out what proportion of Plasmodium falciparum infections are treated in rural Gambia. METHODS: Subjects from four villages in the Gambia were followed over nine months through visits to village health workers. Monthly cross-sectional malaria surveys measured the prevalence of P. falciparum infection. Linked databases were searched for treatment requests. Treated cases were individuals with parasitaemia who requested treatment during narrow or extended periods (14 or 28 days, respectively) before or after a positive blood film was obtained. FINDINGS: Parasite prevalence peaked in November 1998, when 399/653 (61%) individuals had parasitaemia. Parasite prevalence was highest throughout the study in children aged 5-10 years. Although access to treatment was better than in most of sub-Saharan Africa, only 20% of infected individuals sought medical treatment up to 14 days before or after a positive blood film. Within two months of a positive blood film, 199/726 (27%) individuals with parasitaemia requested treatment. Despite easy access to health care, less than half (42%) of those with parasite densities consistent with malaria attacks (5000/ l) requested treatment. High parasite density and infection during October-November were associated with more frequent treatment requests. Self-treatment was infrequent in study villages: in 3/120 (2.5%) households antimalarial drugs had been used in the preceding malaria season. CONCLUSION: Many P. falciparum infections may be untreated because of their subclinical nature. Intermittent presumptive treatment may reduce morbidity and mortality. It is likely that not all untreated infections were asymptomatic. Qualitative research should explore barriers to treatment uptake, to allow educational interventions to be planned. PMID:12471399

  6. Antibody response dynamics to the Plasmodium falciparum conserved vaccine candidate antigen, merozoite surface protein-1 C-terminal 19kD (MSP1-19kD), in Peruvians exposed to hypoendemic malaria transmission

    PubMed Central

    Torres, Katherine J; Clark, Eva H; Hernandez, Jean N; Soto-Cornejo, Katherine E; Gamboa, Dionicia; Branch, OraLee H

    2008-01-01

    Background In high-transmission areas, developing immunity to symptomatic Plasmodium falciparum infections requires 2–10 years of uninterrupted exposure. Delayed malaria-immunity has been attributed to difficult-to-develop and then short-lived antibody responses. Methods In a study area with <0.5 P. falciparum infections/person/year, antibody responses to the MSP1-19kD antigen were evaluated and associations with P. falciparum infections in children and adults. In months surrounding and during the malaria seasons of 2003–2004, 1,772 participants received ≥6 active visits in one study-year. Community-wide surveys were conducted at the beginning and end of each malaria season, and weekly active visits were completed for randomly-selected individuals each month. There were 79 P. falciparum infections with serum samples collected during and approximately one month before and after infection. Anti-MSP1-19kD IgG levels were measured by ELISA. Results The infection prevalence during February-July was similar in children (0.02–0.12 infections/person/month) and adults (0.03–0.14 infections/person/month) and was negligible in the four-month dry season. In children and adults, the seroprevalence was maintained in the beginning (children = 28.9%, adults = 61.8%) versus ending malaria-season community survey (children = 26.7%, adults = 64.6%). Despite the four-month non-transmission season, the IgG levels in Plasmodium-negative adults were similar to P. falciparum-positive adults. Although children frequently responded upon infection, the transition from a negative/low level before infection to a high level during/after infection was slower in children. Adults and children IgG-positive before infection had reduced symptoms and parasite density. Conclusion Individuals in low transmission areas can rapidly develop and maintain αMSP1-19kD IgG responses for >4 months, unlike responses reported in high transmission study areas. A greater immune capacity might contribute

  7. Primaquine or other 8-aminoquinoline for reducing Plasmodium falciparum transmission

    PubMed Central

    Graves, Patricia M; Gelband, Hellen; Garner, Paul

    2015-01-01

    Background Mosquitoes become infected with Plasmodium when they ingest gametocyte-stage parasites from an infected person's blood. Plasmodium falciparum gametocytes are sensitive to the drug primaquine (PQ) and other 8-aminoquinolines (8AQ); these drugs could prevent parasite transmission from infected people to mosquitoes, and consequently reduce the incidence of malaria. However, PQ will not directly benefit the individual, and could be harmful to those with glucose-6-phosphate dehydrogenase (G6PD) deficiency. In 2010, The World Health Organization (WHO) recommended a single dose of PQ at 0.75 mg/kg, alongside treatment for P. falciparum malaria to reduce transmission in areas approaching malaria elimination. In 2013 the WHO revised this to 0.25 mg/kg due to concerns about safety. Objectives To assess whether giving PQ or an alternative 8AQ alongside treatment for P. falciparum malaria reduces malaria transmission, and to estimate the frequency of severe or haematological adverse events when PQ is given for this purpose. Search methods We searched the following databases up to 10 Feb 2014 for trials: the Cochrane Infectious Diseases Group Specialized Register; the Cochrane Central Register of Controlled Trials (CENTRAL), published in The Cochrane Library; MEDLINE; EMBASE; LILACS; metaRegister of Controlled Trials (mRCT); and the WHO trials search portal using 'malaria*', 'falciparum', and 'primaquine' as search terms. In addition, we searched conference proceedings and reference lists of included studies, and contacted researchers and organizations. Selection criteria Randomized controlled trials (RCTs) or quasi-RCTs comparing PQ (or alternative 8AQ) given as a single dose or short course alongside treatment for P. falciparum malaria with malaria treatment given without PQ/8AQ in adults or children. Data collection and analysis Two authors independently screened all abstracts, applied inclusion criteria, and extracted data. We sought evidence of an impact on

  8. The Association of High Prevalence of Trophozoites in Peripheral Blood with Lower Antibody Response to P. falciparum Infected Erythrocytes among Asymptomatic Children in Sudan

    PubMed Central

    Mohamed, Sara N.; Hassan, Dina A.; El Hussein, Abdelrahim M.; Osman, Ihssan M.; Ibrahim, Muntasir E.; Nour, Bakri Y.

    2016-01-01

    Background. The most prominent variant surface antigens (VSAs) of Plasmodium falciparum are the var gene-encoded Plasmodium falciparum erythrocyte membrane protein 1 (PfEMP1) family, which serves as a parasite-sequestering ligand to endothelial cells. In this study we have examined the antibody reactivity of autologous plasma from symptomatic and asymptomatic malaria infected children against the infected erythrocytes' surface antigens using flow cytometry. Methods. Ethidium-bromide-labelled erythrocytic mature forms of P. falciparum parasites obtained from symptomatic and asymptomatic children were sequentially incubated with autologous plasma and fluorescein isothiocyanate-conjugated (FITC) antihuman IgG. Plasma antibody reactivity was detected by flow cytometry. Results. Asymptomatic children had more prevalence of trophozoites in peripheral blood (66%) compared to symptomatic children (16%), p = 0.002. The mean percentage of infected RBCs reacting with autologous sera was 89.78 among symptomatic children compared to 79.62 among asymptomatic children (p = 0.09). Moreover, the mean fluorescence intensity (MFI) in the asymptomatic was significantly higher compared to symptomatic children (p value = 0.040). Conclusion. Variant surface antigens on Plasmodium falciparum infected RBCs from symptomatic malaria children tend to be better recognized by IgG antibodies. This may suggest a role of some IgG antibodies in severity of malaria. PMID:27433028

  9. Interethnic Differences in Antigen-Presenting Cell Activation and TLR Responses in Malian Children during Plasmodium falciparum Malaria

    PubMed Central

    Boström, Stéphanie; Dara, Victor; Traore, Boubacar; Dolo, Amagana; Doumbo, Ogobara; Varani, Stefania; Troye-Blomberg, Marita

    2011-01-01

    The Fulani ethnic group from West Africa is relatively better protected against Plasmodium falciparum malaria as compared to other sympatric ethnic groups, such as the Dogon. However, the mechanisms behind this lower susceptibility to malaria are largely unknown, particularly those concerning innate immunity. Antigen-presenting cells (APCs), and in particular dendritic cells (DCs) are important components of the innate and adaptive immune systems. Therefore, in this study we investigated whether APCs obtained from Fulani and Dogon children exhibited differences in terms of activation status and toll-like receptor (TLR) responses during malaria infection. Lower frequency and increased activation was observed in circulating plasmacytoid DCs and BDCA-3+ myeloid DCs of infected Fulani as compared to their uninfected counterparts. Conversely, a higher frequency and reduced activation was observed in the same DC subsets obtained from peripheral blood of P. falciparum-infected Dogon children as compared to their uninfected peers. Moreover, infected individuals of both ethnic groups exhibited higher percentages of both classical and inflammatory monocytes that were less activated as compared to their non-infected counterparts. In line with APC impairment during malaria infection, TLR4, TLR7 and TLR9 responses were strongly inhibited by P. falciparum infection in Dogon children, while no such TLR inhibition was observed in the Fulani children. Strikingly, the TLR-induced IFN-γ release was completely abolished in the Dogon undergoing infection while no difference was seen within infected and non-infected Fulani. Thus, P. falciparum infection is associated with altered activation status of important APC subsets and strongly inhibited TLR responses in peripheral blood of Dogon children. In contrast, P. falciparum induces DC activation and does not affect the innate response to specific TLR ligands in Fulani children. These findings suggest that DCs and TLR signalling may be

  10. Interethnic differences in antigen-presenting cell activation and TLR responses in Malian children during Plasmodium falciparum malaria.

    PubMed

    Arama, Charles; Giusti, Pablo; Boström, Stéphanie; Dara, Victor; Traore, Boubacar; Dolo, Amagana; Doumbo, Ogobara; Varani, Stefania; Troye-Blomberg, Marita

    2011-03-31

    The Fulani ethnic group from West Africa is relatively better protected against Plasmodium falciparum malaria as compared to other sympatric ethnic groups, such as the Dogon. However, the mechanisms behind this lower susceptibility to malaria are largely unknown, particularly those concerning innate immunity. Antigen-presenting cells (APCs), and in particular dendritic cells (DCs) are important components of the innate and adaptive immune systems. Therefore, in this study we investigated whether APCs obtained from Fulani and Dogon children exhibited differences in terms of activation status and toll-like receptor (TLR) responses during malaria infection. Lower frequency and increased activation was observed in circulating plasmacytoid DCs and BDCA-3+ myeloid DCs of infected Fulani as compared to their uninfected counterparts. Conversely, a higher frequency and reduced activation was observed in the same DC subsets obtained from peripheral blood of P. falciparum-infected Dogon children as compared to their uninfected peers. Moreover, infected individuals of both ethnic groups exhibited higher percentages of both classical and inflammatory monocytes that were less activated as compared to their non-infected counterparts. In line with APC impairment during malaria infection, TLR4, TLR7 and TLR9 responses were strongly inhibited by P. falciparum infection in Dogon children, while no such TLR inhibition was observed in the Fulani children. Strikingly, the TLR-induced IFN-γ release was completely abolished in the Dogon undergoing infection while no difference was seen within infected and non-infected Fulani. Thus, P. falciparum infection is associated with altered activation status of important APC subsets and strongly inhibited TLR responses in peripheral blood of Dogon children. In contrast, P. falciparum induces DC activation and does not affect the innate response to specific TLR ligands in Fulani children. These findings suggest that DCs and TLR signalling may be

  11. Plasmodium falciparum Founder Populations in Western Cambodia Have Reduced Artemisinin Sensitivity In Vitro

    PubMed Central

    Amaratunga, Chanaki; Witkowski, Benoit; Dek, Dalin; Try, Vorleak; Khim, Nimol; Miotto, Olivo

    2014-01-01

    Reduced Plasmodium falciparum sensitivity to short-course artemisinin (ART) monotherapy manifests as a long parasite clearance half-life. We recently defined three parasite founder populations with long half-lives in Pursat, western Cambodia, where reduced ART sensitivity is prevalent. Using the ring-stage survival assay, we show that these founder populations have reduced ART sensitivity in vitro at the early ring stage of parasite development and that a genetically admixed population contains subsets of parasites with normal or reduced ART sensitivity. PMID:24867977

  12. Molecular inference of sources and spreading patterns of Plasmodium falciparum malaria parasites in internally displaced persons settlements in Myanmar-China border area.

    PubMed

    Lo, Eugenia; Zhou, Guofa; Oo, Winny; Lee, Ming-Chieh; Baum, Elisabeth; Felgner, Philip L; Yang, Zhaoqing; Cui, Liwang; Yan, Guiyun

    2015-07-01

    In Myanmar, civil unrest and establishment of internally displaced persons (IDP) settlement along the Myanmar-China border have impacted malaria transmission. The growing IDP populations raise deep concerns about health impact on local communities. Microsatellite markers were used to examine the source and spreading patterns of Plasmodium falciparum between IDP settlement and surrounding villages in Myanmar along the China border. Genotypic structure of P. falciparum was compared over the past three years from the same area and the demographic history was inferred to determine the source of recent infections. In addition, we examined if border migration is a factor of P. falciparum infections in China by determining gene flow patterns across borders. Compared to local community, the IDP samples showed a reduced and consistently lower genetic diversity over the past three years. A strong signature of genetic bottleneck was detected in the IDP samples. P. falciparum infections from the border regions in China were genetically similar to Myanmar and parasite gene flow was not constrained by geographical distance. Reduced genetic diversity of P. falciparum suggested intense malaria control within the IDP settlement. Human movement was a key factor to the spread of malaria both locally in Myanmar and across the international border.

  13. Interactive cost of Plasmodium infection and insecticide resistance in the malaria vector Anopheles gambiae

    PubMed Central

    Alout, Haoues; Dabiré, Roch K.; Djogbénou, Luc S.; Abate, Luc; Corbel, Vincent; Chandre, Fabrice; Cohuet, Anna

    2016-01-01

    Insecticide resistance raises concerns for the control of vector-borne diseases. However, its impact on parasite transmission could be diverse when considering the ecological interactions between vector and parasite. Thus we investigated the fitness cost associated with insecticide resistance and Plasmodium falciparum infection as well as their interactive cost on Anopheles gambiae survival and fecundity. In absence of infection, we observed a cost on fecundity associated with insecticide resistance. However, survival was higher for mosquito bearing the kdr mutation and equal for those with the ace-1R mutation compared to their insecticide susceptible counterparts. Interestingly, Plasmodium infection reduced survival only in the insecticide resistant strains but not in the susceptible one and infection was associated with an increase in fecundity independently of the strain considered. This study provides evidence for a survival cost associated with infection by Plasmodium parasite only in mosquito selected for insecticide resistance. This suggests that the selection of insecticide resistance mutation may have disturbed the interaction between parasites and vectors, resulting in increased cost of infection. Considering the fitness cost as well as other ecological aspects of this natural mosquito-parasite combination is important to predict the epidemiological impact of insecticide resistance. PMID:27432257

  14. Purification Methodology for Viable and Infective Plasmodium vivax Gametocytes That Is Compatible with Transmission-Blocking Assays

    PubMed Central

    Vera, Omaira; Brelas de Brito, Paula; Albrecht, Letusa; Martins-Campos, Keillen Monick; Pimenta, Paulo F. P.; Monteiro, Wuelton M.; Lacerda, Marcus V. G.

    2015-01-01

    Significant progress toward the control of malaria has been achieved, especially regarding Plasmodium falciparum infections. However, the unique biology of Plasmodium vivax hampers current control strategies. The early appearance of P. vivax gametocytes in the peripheral blood and the impossibility of culturing this parasite are major drawbacks. Using blood samples from 40 P. vivax-infected patients, we describe here a methodology to purify viable gametocytes and further infect anophelines. This method opens new avenues to validate transmission-blocking strategies. PMID:26239989

  15. Human immune responses that reduce the transmission of Plasmodium falciparum in African populations

    PubMed Central

    Bousema, Teun; Sutherland, Colin J.; Churcher, Thomas S.; Mulder, Bert; Gouagna, Louis C.; Riley, Eleanor M.; Targett, Geoffrey A.T.; Drakeley, Chris J.

    2011-01-01

    Malaria-infected individuals can develop antibodies which reduce the infectiousness of Plasmodium gametocytes to biting Anopheles mosquitoes. When ingested in a bloodmeal together with gametocytes, these antibodies reduce or prevent subsequent parasite maturation in the insect host. This transmission-blocking immunity is usually measured in human sera by testing its effect on the infectivity of gametocytes grown in vitro. Here we evaluate evidence of transmission-blocking immunity in eight studies conducted in three African countries. Plasmodium falciparum gametocytes isolated from each individual were fed to mosquitoes in both autologous plasma collected with the parasites, and permissive serum from non-exposed donors. Evidence of transmission reducing effects of autologous plasma was found in all countries. Experiments involving 116 Gambian children (aged 0.5–15 years) were combined to determine which factors were associated with transmission reducing immune responses. The chances of infecting at least one mosquito and the average proportion of infected mosquitoes were negatively associated with recent exposure to gametocytes and sampling late in the season. These results suggest that effective malaria transmission-reducing antibodies do not commonly circulate in African children, and that recent gametocyte carriage is required to initiate and/or boost such responses. PMID:20974145

  16. Disruption of Parasite hmgb2 Gene Attenuates Plasmodium berghei ANKA Pathogenicity

    PubMed Central

    Lawson-Hogban, Nadou; Boisson, Bertrand; Soares, Miguel P.; Péronet, Roger; Smith, Leanna; Ménard, Robert; Huerre, Michel; Mécheri, Salah

    2015-01-01

    Eukaryotic high-mobility-group-box (HMGB) proteins are nuclear factors involved in chromatin remodeling and transcription regulation. When released into the extracellular milieu, HMGB1 acts as a proinflammatory cytokine that plays a central role in the pathogenesis of several immune-mediated inflammatory diseases. We found that the Plasmodium genome encodes two genuine HMGB factors, Plasmodium HMGB1 and HMGB2, that encompass, like their human counterparts, a proinflammatory domain. Given that these proteins are released from parasitized red blood cells, we then hypothesized that Plasmodium HMGB might contribute to the pathogenesis of experimental cerebral malaria (ECM), a lethal neuroinflammatory syndrome that develops in C57BL/6 (susceptible) mice infected with Plasmodium berghei ANKA and that in many aspects resembles human cerebral malaria elicited by P. falciparum infection. The pathogenesis of experimental cerebral malaria was suppressed in C57BL/6 mice infected with P. berghei ANKA lacking the hmgb2 gene (Δhmgb2 ANKA), an effect associated with a reduction of histological brain lesions and with lower expression levels of several proinflammatory genes. The incidence of ECM in pbhmgb2-deficient mice was restored by the administration of recombinant PbHMGB2. Protection from experimental cerebral malaria in Δhmgb2 ANKA-infected mice was associated with reduced sequestration in the brain of CD4+ and CD8+ T cells, including CD8+ granzyme B+ and CD8+ IFN-γ+ cells, and, to some extent, neutrophils. This was consistent with a reduced parasite sequestration in the brain, lungs, and spleen, though to a lesser extent than in wild-type P. berghei ANKA-infected mice. In summary, Plasmodium HMGB2 acts as an alarmin that contributes to the pathogenesis of cerebral malaria. PMID:25916985

  17. Disruption of Parasite hmgb2 Gene Attenuates Plasmodium berghei ANKA Pathogenicity.

    PubMed

    Briquet, Sylvie; Lawson-Hogban, Nadou; Boisson, Bertrand; Soares, Miguel P; Péronet, Roger; Smith, Leanna; Ménard, Robert; Huerre, Michel; Mécheri, Salah; Vaquero, Catherine

    2015-07-01

    Eukaryotic high-mobility-group-box (HMGB) proteins are nuclear factors involved in chromatin remodeling and transcription regulation. When released into the extracellular milieu, HMGB1 acts as a proinflammatory cytokine that plays a central role in the pathogenesis of several immune-mediated inflammatory diseases. We found that the Plasmodium genome encodes two genuine HMGB factors, Plasmodium HMGB1 and HMGB2, that encompass, like their human counterparts, a proinflammatory domain. Given that these proteins are released from parasitized red blood cells, we then hypothesized that Plasmodium HMGB might contribute to the pathogenesis of experimental cerebral malaria (ECM), a lethal neuroinflammatory syndrome that develops in C57BL/6 (susceptible) mice infected with Plasmodium berghei ANKA and that in many aspects resembles human cerebral malaria elicited by P. falciparum infection. The pathogenesis of experimental cerebral malaria was suppressed in C57BL/6 mice infected with P. berghei ANKA lacking the hmgb2 gene (Δhmgb2 ANKA), an effect associated with a reduction of histological brain lesions and with lower expression levels of several proinflammatory genes. The incidence of ECM in pbhmgb2-deficient mice was restored by the administration of recombinant PbHMGB2. Protection from experimental cerebral malaria in Δhmgb2 ANKA-infected mice was associated with reduced sequestration in the brain of CD4(+) and CD8(+) T cells, including CD8(+) granzyme B(+) and CD8(+) IFN-γ(+) cells, and, to some extent, neutrophils. This was consistent with a reduced parasite sequestration in the brain, lungs, and spleen, though to a lesser extent than in wild-type P. berghei ANKA-infected mice. In summary, Plasmodium HMGB2 acts as an alarmin that contributes to the pathogenesis of cerebral malaria. PMID:25916985

  18. Disruption of Parasite hmgb2 Gene Attenuates Plasmodium berghei ANKA Pathogenicity.

    PubMed

    Briquet, Sylvie; Lawson-Hogban, Nadou; Boisson, Bertrand; Soares, Miguel P; Péronet, Roger; Smith, Leanna; Ménard, Robert; Huerre, Michel; Mécheri, Salah; Vaquero, Catherine

    2015-07-01

    Eukaryotic high-mobility-group-box (HMGB) proteins are nuclear factors involved in chromatin remodeling and transcription regulation. When released into the extracellular milieu, HMGB1 acts as a proinflammatory cytokine that plays a central role in the pathogenesis of several immune-mediated inflammatory diseases. We found that the Plasmodium genome encodes two genuine HMGB factors, Plasmodium HMGB1 and HMGB2, that encompass, like their human counterparts, a proinflammatory domain. Given that these proteins are released from parasitized red blood cells, we then hypothesized that Plasmodium HMGB might contribute to the pathogenesis of experimental cerebral malaria (ECM), a lethal neuroinflammatory syndrome that develops in C57BL/6 (susceptible) mice infected with Plasmodium berghei ANKA and that in many aspects resembles human cerebral malaria elicited by P. falciparum infection. The pathogenesis of experimental cerebral malaria was suppressed in C57BL/6 mice infected with P. berghei ANKA lacking the hmgb2 gene (Δhmgb2 ANKA), an effect associated with a reduction of histological brain lesions and with lower expression levels of several proinflammatory genes. The incidence of ECM in pbhmgb2-deficient mice was restored by the administration of recombinant PbHMGB2. Protection from experimental cerebral malaria in Δhmgb2 ANKA-infected mice was associated with reduced sequestration in the brain of CD4(+) and CD8(+) T cells, including CD8(+) granzyme B(+) and CD8(+) IFN-γ(+) cells, and, to some extent, neutrophils. This was consistent with a reduced parasite sequestration in the brain, lungs, and spleen, though to a lesser extent than in wild-type P. berghei ANKA-infected mice. In summary, Plasmodium HMGB2 acts as an alarmin that contributes to the pathogenesis of cerebral malaria.

  19. Plasmodium falciparum Na+/H+ Exchanger 1 Transporter Is Involved in Reduced Susceptibility to Quinine ▿

    PubMed Central

    Henry, Maud; Briolant, Sébastien; Zettor, Agnès; Pelleau, Stéphane; Baragatti, Meili; Baret, Eric; Mosnier, Joel; Amalvict, Rémy; Fusai, Thierry; Rogier, Christophe; Pradines, Bruno

    2009-01-01

    Polymorphisms in the Plasmodium falciparum crt (Pfcrt), Pfmdr1, and Pfmrp genes were not significantly associated with quinine (QN) 50% inhibitory concentrations (IC50s) in 23 strains of Plasmodium falciparum. An increased number of DNNND repeats in Pfnhe-1 microsatellite ms4760 was associated with an increased IC50 of QN (P = 0.0007). Strains with only one DNNND repeat were more susceptible to QN (mean IC50 of 154 nM). Strains with two DNNND repeats had intermediate susceptibility to QN (mean IC50 of 548 nM). Strains with three DNNND repeats had reduced susceptibility to QN (mean IC50 of 764 nM). Increased numbers of NHNDNHNNDDD repeats were associated with a decreased IC50 of QN (P = 0.0020). Strains with profile 7 for Pfnhe-1 ms4760 (ms4760-7) were significantly associated with reduced QN susceptibility (mean IC50 of 764 nM). The determination of DNNND and NHNDNHNNDDD repeats in Pfnhe-1 ms4760 could be a good marker of QN resistance and provide an attractive surveillance method to monitor temporal trends in P. falciparum susceptibility to QN. The validity of the markers should be further supported by analyzing more isolates. PMID:19273668

  20. Plasmodium falciparum Plasmodium helical interspersed subtelomeric proteins contribute to cytoadherence and anchor P. falciparum erythrocyte membrane protein 1 to the host cell cytoskeleton.

    PubMed

    Oberli, Alexander; Zurbrügg, Laura; Rusch, Sebastian; Brand, Françoise; Butler, Madeleine E; Day, Jemma L; Cutts, Erin E; Lavstsen, Thomas; Vakonakis, Ioannis; Beck, Hans-Peter

    2016-10-01

    Adherence of Plasmodium falciparum-infected erythrocytes to host endothelium is conferred through the parasite-derived virulence factor P. falciparum erythrocyte membrane protein 1 (PfEMP1), the major contributor to malaria severity. PfEMP1 located at knob structures on the erythrocyte surface is anchored to the cytoskeleton, and the Plasmodium helical interspersed subtelomeric (PHIST) gene family plays a role in many host cell modifications including binding the intracellular domain of PfEMP1. Here, we show that conditional reduction of the PHIST protein PFE1605w strongly reduces adhesion of infected erythrocytes to the endothelial receptor CD36. Adhesion to other endothelial receptors was less affected or even unaltered by PFE1605w depletion, suggesting that PHIST proteins might be optimized for subsets of PfEMP1 variants. PFE1605w does not play a role in PfEMP1 transport, but it directly interacts with both the intracellular segment of PfEMP1 and with cytoskeletal components. This is the first report of a PHIST protein interacting with key molecules of the cytoadherence complex and the host cytoskeleton, and this functional role seems to play an essential role in the pathology of P. falciparum.

  1. Parasite-induced permeation of nucleosides in Plasmodium falciparum malaria.

    PubMed

    Upston, J M; Gero, A M

    1995-06-14

    A mechanism which mediates the transport of the nonphysiological nucleoside, L-adenosine, was demonstrated in Plasmodium falciparum infected erythrocytes and naturally released merozoites. L-Adenosine was not a substrate for influx in freed intraerythrocytic parasites or in normal human erythrocytes nor was L-adenosine transported in a variety of cell types including other parasitic protozoa such as Crithidia luciliae, Trichomonas vaginalis, Giardia intestinalis, or the mammalian cells, Buffalo Green Monkey and HeLa cells. L-Adenosine transport in P. falciparum infected cells was nonsaturable, with a rate of 0.13 +/- 0.01 pmol/microliter cell water per s per microM L-adenosine, yet the transport was inhibited by furosemide, phloridzin and piperine with IC50 values between 1-13 microM, distinguishing the transport pathway from simple diffusion. The channel-like permeation was selective as disaccharides were not permeable to parasitised cells. In addition, an unusual metabolic property of parasitic adenosine deaminase was found in that L-adenosine was metabolised to L-inosine by both P. falciparum infected erythrocytes and merozoites, an activity which was inhibited by 50 nM deoxycoformycin. No other cell type examined displayed this enzymic activity. The results further substantiate that nucleoside transport in P. falciparum infected cells was significantly altered compared to uninfected erythrocytes and that L-adenosine transport and metabolism was a biochemical property of Plasmodium infected cells and merozoites and not found in normal erythrocytes nor any of the other cell types investigated.

  2. Clinical Indicators for Bacterial Co-Infection in Ghanaian Children with P. falciparum Infection

    PubMed Central

    Nielsen, Maja Verena; Amemasor, Solomon; Agyekum, Alex; Loag, Wibke; Marks, Florian; Sarpong, Nimako; Dekker, Denise; Adu-Sarkodie, Yaw; May, Jürgen

    2015-01-01

    Differentiation of infectious causes in severely ill children is essential but challenging in sub- Saharan Africa. The aim of the study was to determine clinical indicators that are able to identify bacterial co-infections in P. falciparum infected children in rural Ghana. In total, 1,915 severely ill children below the age of 15 years were recruited at Agogo Presbyterian Hospital in Ghana between May 2007 and February 2011. In 771 (40%) of the children malaria parasites were detected. This group was analyzed for indicators of bacterial co-infections using bivariate and multivariate regression analyses with 24 socio-economic variables, 16 terms describing medical history and anthropometrical information and 68 variables describing clinical symptoms. The variables were tested for sensitivity, specificity, positive predictive value and negative predictive value. In 46 (6.0%) of the children with malaria infection, bacterial co-infection was detected. The most frequent pathogens were non-typhoid salmonellae (45.7%), followed by Streptococcus spp. (13.0%). Coughing, dehydration, splenomegaly, severe anemia and leukocytosis were positively associated with bacteremia. Domestic hygiene and exclusive breastfeeding is negatively associated with bacteremia. In cases of high parasitemia (>10,000/μl), a significant association with bacteremia was found for splenomegaly (OR 8.8; CI 1.6–48.9), dehydration (OR 18.2; CI 2.0–166.0) and coughing (OR 9.0; CI 0.7–118.6). In children with low parasitemia, associations with bacteremia were found for vomiting (OR 4.7; CI 1.4–15.8), severe anemia (OR 3.3; CI 1.0–11.1) and leukocytosis (OR 6.8 CI 1.9–24.2). Clinical signs of impaired microcirculation were negatively associated with bacteremia. Ceftriaxone achieved best coverage of isolated pathogens. The results demonstrate the limitation of clinical symptoms to determine bacterial co-infections in P. falciparum infected children. Best clinical indicators are dependent on the

  3. Reduced Artemisinin Susceptibility of Plasmodium falciparum Ring Stages in Western Cambodia

    PubMed Central

    Khim, Nimol; Chim, Pheaktra; Kim, Saorin; Ke, Sopheakvatey; Kloeung, Nimol; Chy, Sophy; Duong, Socheat; Leang, Rithea; Ringwald, Pascal; Dondorp, Arjen M.; Tripura, Rupam; Benoit-Vical, Françoise; Berry, Antoine; Gorgette, Olivier; Ariey, Frédéric; Barale, Jean-Christophe; Mercereau-Puijalon, Odile

    2013-01-01

    The declining efficacy of artemisinin derivatives against Plasmodium falciparum in western Cambodia is a major concern. The knowledge gap in the understanding of the mechanisms involved hampers designing monitoring tools. Here, we culture-adapted 20 isolates from Pailin and Ratanakiri (areas of artemisinin resistance and susceptibility in western and eastern Cambodia, respectively) and studied their in vitro response to dihydroartemisinin. No significant difference between the two sets of isolates was observed in the classical isotopic test. However, a 6-h pulse exposure to 700 nM dihydroartemisinin (ring-stage survival assay -RSA]) revealed a clear-cut geographic dichotomy. The survival rate of exposed ring-stage parasites (ring stages) was 17-fold higher in isolates from Pailin (median, 13.5%) than in those from Ratanakiri (median, 0.8%), while exposed mature stages were equally and highly susceptible (0.6% and 0.7%, respectively). Ring stages survived drug exposure by cell cycle arrest and resumed growth upon drug withdrawal. The reduced susceptibility to artemisinin in Pailin appears to be associated with an altered in vitro phenotype of ring stages from Pailin in the RSA. PMID:23208708

  4. Reduced Plasmodium Parasite Burden Associates with CD38+ CD4+ T Cells Displaying Cytolytic Potential and Impaired IFN-γ Production

    PubMed Central

    Burel, Julie G.; Apte, Simon H.; Groves, Penny L.; Klein, Kerenaftali; McCarthy, James S.; Doolan, Denise L.

    2016-01-01

    Using a unique resource of samples from a controlled human malaria infection (CHMI) study, we identified a novel population of CD4+ T cells whose frequency in the peripheral blood was inversely correlated with parasite burden following P. falciparum infection. These CD4+ T cells expressed the multifunctional ectoenzyme CD38 and had unique features that distinguished them from other CD4+ T cells. Specifically, their phenotype was associated with proliferation, activation and cytotoxic potential as well as significantly impaired production of IFN-γ and other cytokines and reduced basal levels of activated STAT1. A CD38+ CD4+ T cell population with similar features was identified in healthy uninfected individuals, at lower frequency. CD38+ CD4+ T cells could be generated in vitro from CD38- CD4+ T cells after antigenic or mitogenic stimulation. This is the first report of a population of CD38+ CD4+ T cells with a cytotoxic phenotype and markedly impaired IFN-γ capacity in humans. The expansion of this CD38+ CD4+ T population following infection and its significant association with reduced blood-stage parasite burden is consistent with an important functional role for these cells in protective immunity to malaria in humans. Their ubiquitous presence in humans suggests that they may have a broad role in host-pathogen defense. Trial Registration ClinicalTrials.gov clinical trial numbers ACTRN12612000814875, ACTRN12613000565741 and ACTRN12613001040752 PMID:27662621

  5. A high-sensitivity HPLC assay for measuring intracellular Na+ and K+ and its application to Plasmodium falciparum infected erythrocytes

    PubMed Central

    Winterberg, Markus; Kirk, Kiaran

    2016-01-01

    The measurement of intracellular ion concentrations, and the screening of chemical agents to identify molecules targeting ion transport, has traditionally involved low-throughput techniques. Here we present a novel HPLC method that allows the rapid, high-sensitivity measurement of cell Na+ and K+ content, demonstrating its utility by monitoring the ionic changes induced in the intracellular malaria parasite by the new spiroindolone antimalarial KAE609. PMID:27385291

  6. A simple protocol for platelet-mediated clumping of Plasmodium falciparum-infected erythrocytes in a resource poor setting.

    PubMed

    Tembo, Dumizulu L; Montgomery, Jacqui; Craig, Alister G; Wassmer, Samuel C

    2013-01-01

    P. falciparum causes the majority of severe malarial infections. The pathophysiological mechanisms underlying cerebral malaria (CM) are not fully understood and several hypotheses have been put forward, including mechanical obstruction of microvessels by P. falciparum-parasitized red blood cells (pRBC). Indeed, during the intra-erythrocytic stage of its life cycle, P. falciparum has the unique ability to modify the surface of the infected erythrocyte by exporting surface antigens with varying adhesive properties onto the RBC membrane. This allows the sequestration of pRBC in multiple tissues and organs by adhesion to endothelial cells lining the microvasculature of post-capillary venules (1). By doing so, the mature forms of the parasite avoid splenic clearance of the deformed infected erythrocytes (2) and restrict their environment to a more favorable low oxygen pressure (3). As a consequence of this sequestration, it is only immature asexual parasites and gametocytes that can be detected in peripheral blood. Cytoadherence and sequestration of mature pRBC to the numerous host receptors expressed on microvascular beds occurs in severe and uncomplicated disease. However, several lines of evidence suggest that only specific adhesive phenotypes are likely to be associated with severe pathological outcomes of malaria. One example of such specific host-parasite interactions has been demonstrated in vitro, where the ability of intercellular adhesion molecule-1 to support binding of pRBC with particular adhesive properties has been linked to development of cerebral malaria (4,5). The placenta has also been recognized as a site of preferential pRBC accumulation in malaria-infected pregnant women, with chondrotin sulphate A expressed on syncytiotrophoblasts that line the placental intervillous space as the main receptor (6). Rosetting of pRBC to uninfected erythrocytes via the complement receptor 1 (CD35)(7,8) has also been associated with severe disease (9). One of the most recently described P. falciparum cytoadherence phenotypes is the ability of the pRBC to form platelet-mediated clumps in vitro. The formation of such pRBC clumps requires CD36, a glycoprotein expressed on the surface of platelets. Another human receptor, gC1qR/HABP1/p32, expressed on diverse cell types including endothelial cells and platelets, has also been shown to facilitate pRBC adhesion on platelets to form clumps (10). Whether clumping occurs in vivo remains unclear, but it may account for the significant accumulation of platelets described in brain microvasculature of Malawian children who died from CM (11). In addition, the ability of clinical isolate cultures to clump in vitro was directly linked to the severity of disease in Malawian (12) and Mozambican patients (13), (although not in Malian (14)). With several aspects of the pRBC clumping phenotype poorly characterized, current studies on this subject have not followed a standardized procedure. This is an important issue because of the known high variability inherent in the assay (15). Here, we present a method for in vitro platelet-mediated clumping of P. falciparum with hopes that it will provide a platform for a consistent method for other groups and raise awareness of the limitations in investigating this phenotype in future studies. Being based in Malawi, we provide a protocol specifically designed for a limited resource setting, with the advantage that freshly collected clinical isolates can be examined for phenotype without need for cryopreservation. PMID:23711755

  7. A simple protocol for platelet-mediated clumping of Plasmodium falciparum-infected erythrocytes in a resource poor setting.

    PubMed

    Tembo, Dumizulu L; Montgomery, Jacqui; Craig, Alister G; Wassmer, Samuel C

    2013-01-01

    P. falciparum causes the majority of severe malarial infections. The pathophysiological mechanisms underlying cerebral malaria (CM) are not fully understood and several hypotheses have been put forward, including mechanical obstruction of microvessels by P. falciparum-parasitized red blood cells (pRBC). Indeed, during the intra-erythrocytic stage of its life cycle, P. falciparum has the unique ability to modify the surface of the infected erythrocyte by exporting surface antigens with varying adhesive properties onto the RBC membrane. This allows the sequestration of pRBC in multiple tissues and organs by adhesion to endothelial cells lining the microvasculature of post-capillary venules (1). By doing so, the mature forms of the parasite avoid splenic clearance of the deformed infected erythrocytes (2) and restrict their environment to a more favorable low oxygen pressure (3). As a consequence of this sequestration, it is only immature asexual parasites and gametocytes that can be detected in peripheral blood. Cytoadherence and sequestration of mature pRBC to the numerous host receptors expressed on microvascular beds occurs in severe and uncomplicated disease. However, several lines of evidence suggest that only specific adhesive phenotypes are likely to be associated with severe pathological outcomes of malaria. One example of such specific host-parasite interactions has been demonstrated in vitro, where the ability of intercellular adhesion molecule-1 to support binding of pRBC with particular adhesive properties has been linked to development of cerebral malaria (4,5). The placenta has also been recognized as a site of preferential pRBC accumulation in malaria-infected pregnant women, with chondrotin sulphate A expressed on syncytiotrophoblasts that line the placental intervillous space as the main receptor (6). Rosetting of pRBC to uninfected erythrocytes via the complement receptor 1 (CD35)(7,8) has also been associated with severe disease (9). One of the most recently described P. falciparum cytoadherence phenotypes is the ability of the pRBC to form platelet-mediated clumps in vitro. The formation of such pRBC clumps requires CD36, a glycoprotein expressed on the surface of platelets. Another human receptor, gC1qR/HABP1/p32, expressed on diverse cell types including endothelial cells and platelets, has also been shown to facilitate pRBC adhesion on platelets to form clumps (10). Whether clumping occurs in vivo remains unclear, but it may account for the significant accumulation of platelets described in brain microvasculature of Malawian children who died from CM (11). In addition, the ability of clinical isolate cultures to clump in vitro was directly linked to the severity of disease in Malawian (12) and Mozambican patients (13), (although not in Malian (14)). With several aspects of the pRBC clumping phenotype poorly characterized, current studies on this subject have not followed a standardized procedure. This is an important issue because of the known high variability inherent in the assay (15). Here, we present a method for in vitro platelet-mediated clumping of P. falciparum with hopes that it will provide a platform for a consistent method for other groups and raise awareness of the limitations in investigating this phenotype in future studies. Being based in Malawi, we provide a protocol specifically designed for a limited resource setting, with the advantage that freshly collected clinical isolates can be examined for phenotype without need for cryopreservation.

  8. Impact of age of first exposure to Plasmodium falciparum on antibody responses to malaria in children: a randomized, controlled trial in Mozambique

    PubMed Central

    2014-01-01

    Background The impact of the age of first Plasmodium falciparum infection on the rate of acquisition of immunity to malaria and on the immune correlates of protection has proven difficult to elucidate. A randomized, double-blind, placebo-controlled trial using monthly chemoprophylaxis with sulphadoxine-pyrimethamine plus artesunate was conducted to modify the age of first P. falciparum erythrocytic exposure in infancy and assess antibodies and malaria risk over two years. Methods Participants (n = 349) were enrolled at birth to one of three groups: late exposure, early exposure and control group, and were followed up for malaria morbidity and immunological analyses at birth, 2.5, 5.5, 10.5, 15 and 24 months of age. Total IgG, IgG subclasses and IgM responses to MSP-119, AMA-1, and EBA-175 were measured by ELISA, and IgG against variant antigens on the surface of infected erythrocytes by flow cytometry. Factors affecting antibody responses in relation to chemoprophylaxis and malaria incidence were evaluated. Results Generally, antibody responses did not vary significantly between exposure groups except for levels of IgM to EBA-175, and seropositivity of IgG1 and IgG3 to MSP-119. Previous and current malaria infections were strongly associated with increased IgG against MSP-119, EBA-175 and AMA-1 (p < 0.0001). After adjusting for exposure, only higher levels of anti-EBA-175 IgG were significantly associated with reduced clinical malaria incidence (IRR 0.67, p = 0.0178). Conclusions Overall, the age of first P. falciparum infection did not influence the magnitude and breadth of IgG responses, but previous exposure was critical for antibody acquisition. IgG responses to EBA-175 were the strongest correlate of protection against clinical malaria. Trial registration ClinicalTrials.gov: NCT00231452. PMID:24674654

  9. Reduced ribosomes of the apicoplast and mitochondrion of Plasmodium spp. and predicted interactions with antibiotics.

    PubMed

    Gupta, Ankit; Shah, Priyanka; Haider, Afreen; Gupta, Kirti; Siddiqi, Mohammad Imran; Ralph, Stuart A; Habib, Saman

    2014-05-01

    Apicomplexan protists such as Plasmodium and Toxoplasma contain a mitochondrion and a relic plastid (apicoplast) that are sites of protein translation. Although there is emerging interest in the partitioning and function of translation factors that participate in apicoplast and mitochondrial peptide synthesis, the composition of organellar ribosomes remains to be elucidated. We carried out an analysis of the complement of core ribosomal protein subunits that are encoded by either the parasite organellar or nuclear genomes, accompanied by a survey of ribosome assembly factors for the apicoplast and mitochondrion. A cross-species comparison with other apicomplexan, algal and diatom species revealed compositional differences in apicomplexan organelle ribosomes and identified considerable reduction and divergence with ribosomes of bacteria or characterized organelle ribosomes from other organisms. We assembled structural models of sections of Plasmodium falciparum organellar ribosomes and predicted interactions with translation inhibitory antibiotics. Differences in predicted drug-ribosome interactions with some of the modelled structures suggested specificity of inhibition between the apicoplast and mitochondrion. Our results indicate that Plasmodium and Toxoplasma organellar ribosomes have a unique composition, resulting from the loss of several large and small subunit proteins accompanied by significant sequence and size divergences in parasite orthologues of ribosomal proteins.

  10. The effect of malaria control on Plasmodium falciparum in Africa between 2000 and 2015.

    PubMed

    Bhatt, S; Weiss, D J; Cameron, E; Bisanzio, D; Mappin, B; Dalrymple, U; Battle, K E; Moyes, C L; Henry, A; Eckhoff, P A; Wenger, E A; Briët, O; Penny, M A; Smith, T A; Bennett, A; Yukich, J; Eisele, T P; Griffin, J T; Fergus, C A; Lynch, M; Lindgren, F; Cohen, J M; Murray, C L J; Smith, D L; Hay, S I; Cibulskis, R E; Gething, P W

    2015-10-01

    Since the year 2000, a concerted campaign against malaria has led to unprecedented levels of intervention coverage across sub-Saharan Africa. Understanding the effect of this control effort is vital to inform future control planning. However, the effect of malaria interventions across the varied epidemiological settings of Africa remains poorly understood owing to the absence of reliable surveillance data and the simplistic approaches underlying current disease estimates. Here we link a large database of malaria field surveys with detailed reconstructions of changing intervention coverage to directly evaluate trends from 2000 to 2015, and quantify the attributable effect of malaria disease control efforts. We found that Plasmodium falciparum infection prevalence in endemic Africa halved and the incidence of clinical disease fell by 40% between 2000 and 2015. We estimate that interventions have averted 663 (542-753 credible interval) million clinical cases since 2000. Insecticide-treated nets, the most widespread intervention, were by far the largest contributor (68% of cases averted). Although still below target levels, current malaria interventions have substantially reduced malaria disease incidence across the continent. Increasing access to these interventions, and maintaining their effectiveness in the face of insecticide and drug resistance, should form a cornerstone of post-2015 control strategies.

  11. Plasmodium falciparum var genes expressed in children with severe malaria encode CIDRα1 domains.

    PubMed

    Jespersen, Jakob S; Wang, Christian W; Mkumbaye, Sixbert I; Minja, Daniel Tr; Petersen, Bent; Turner, Louise; Petersen, Jens Ev; Lusingu, John Pa; Theander, Thor G; Lavstsen, Thomas

    2016-01-01

    Most severe Plasmodium falciparum infections are experienced by young children. Severe symptoms are precipitated by vascular sequestration of parasites expressing a particular subset of the polymorphic P. falciparum erythrocyte membrane protein 1 (PfEMP1) adhesion molecules. Parasites binding human endothelial protein C receptor (EPCR) through the CIDRα1 domain of certain PfEMP1 were recently associated with severe malaria in children. However, it has remained unclear to which extend the EPCR-binding CIDRα1 domains epitomize PfEMP1 expressed in severe malaria. Here, we characterized the near full-length transcripts dominating the var transcriptome in children with severe malaria and found that the only common feature of the encoded PfEMP1 was CIDRα1 domains. Such genes were highly and dominantly expressed in both children with severe malarial anaemia and cerebral malaria. These observations support the hypothesis that the CIDRα1-EPCR interaction is key to the pathogenesis of severe malaria and strengthen the rationale for pursuing a vaccine or adjunctive treatment aiming at inhibiting or reducing the damaging effects of this interaction. PMID:27354391

  12. The effect of malaria control on Plasmodium falciparum in Africa between 2000 and 2015.

    PubMed

    Bhatt, S; Weiss, D J; Cameron, E; Bisanzio, D; Mappin, B; Dalrymple, U; Battle, K E; Moyes, C L; Henry, A; Eckhoff, P A; Wenger, E A; Briët, O; Penny, M A; Smith, T A; Bennett, A; Yukich, J; Eisele, T P; Griffin, J T; Fergus, C A; Lynch, M; Lindgren, F; Cohen, J M; Murray, C L J; Smith, D L; Hay, S I; Cibulskis, R E; Gething, P W

    2015-10-01

    Since the year 2000, a concerted campaign against malaria has led to unprecedented levels of intervention coverage across sub-Saharan Africa. Understanding the effect of this control effort is vital to inform future control planning. However, the effect of malaria interventions across the varied epidemiological settings of Africa remains poorly understood owing to the absence of reliable surveillance data and the simplistic approaches underlying current disease estimates. Here we link a large database of malaria field surveys with detailed reconstructions of changing intervention coverage to directly evaluate trends from 2000 to 2015, and quantify the attributable effect of malaria disease control efforts. We found that Plasmodium falciparum infection prevalence in endemic Africa halved and the incidence of clinical disease fell by 40% between 2000 and 2015. We estimate that interventions have averted 663 (542-753 credible interval) million clinical cases since 2000. Insecticide-treated nets, the most widespread intervention, were by far the largest contributor (68% of cases averted). Although still below target levels, current malaria interventions have substantially reduced malaria disease incidence across the continent. Increasing access to these interventions, and maintaining their effectiveness in the face of insecticide and drug resistance, should form a cornerstone of post-2015 control strategies. PMID:26375008

  13. Balancing drug resistance and growth rates via compensatory mutations in the Plasmodium falciparum chloroquine resistance transporter

    PubMed Central

    Petersen, Ines; Gabryszewski, Stanislaw J.; Johnston, Geoffrey L.; Dhingra, Satish K.; Ecker, Andrea; Lewis, Rebecca E.; de Almeida, Mariana Justino; Straimer, Judith; Henrich, Philipp H.; Palatulan, Eugene; Johnson, David J.; Coburn-Flynn, Olivia; Sanchez, Cecilia; Lehane, Adele M.; Lanzer, Michael; Fidock, David A.

    2015-01-01

    Summary The widespread use of chloroquine to treat Plasmodium falciparum infections has resulted in the selection and dissemination of variant haplotypes of the primary resistance determinant PfCRT. These haplotypes have encountered drug pressure and within-host competition with wild-type drug-sensitive parasites. To examine these selective forces in vitro, we genetically engineered P. falciparum to express geographically diverse PfCRT haplotypes. Variant alleles from the Philippines (PH1 and PH2, which differ solely by the C72S mutation) both conferred a moderate gain of chloroquine resistance and a reduction in growth rates in vitro. Of the two, PH2 showed higher IC50 values, contrasting with reduced growth. Furthermore, a highly mutated pfcrt allele from Cambodia (Cam734) conferred moderate chloroquine resistance and enhanced growth rates, when tested against wild-type pfcrt in co-culture competition assays. These three alleles mediated cross-resistance to amodiaquine, an antimalarial drug widely used in Africa. Each allele, along with the globally prevalent Dd2 and 7G8 alleles, rendered parasites more susceptible to lumefantrine, the partner drug used in the leading first-line artemisinin-based combination therapy. These data reveal ongoing region-specific evolution of PfCRT that impacts drug susceptibility and relative fitness in settings of mixed infections, and raise important considerations about optimal agents to treat chloroquine-resistant malaria. PMID:25898991

  14. Within-host competition and drug resistance in the human malaria parasite Plasmodium falciparum.

    PubMed

    Bushman, Mary; Morton, Lindsay; Duah, Nancy; Quashie, Neils; Abuaku, Benjamin; Koram, Kwadwo A; Dimbu, Pedro Rafael; Plucinski, Mateusz; Gutman, Julie; Lyaruu, Peter; Kachur, S Patrick; de Roode, Jacobus C; Udhayakumar, Venkatachalam

    2016-03-16

    Infections with the malaria parasite Plasmodium falciparum typically comprise multiple strains, especially in high-transmission areas where infectious mosquito bites occur frequently. However, little is known about the dynamics of mixed-strain infections, particularly whether strains sharing a host compete or grow independently. Competition between drug-sensitive and drug-resistant strains, if it occurs, could be a crucial determinant of the spread of resistance. We analysed 1341 P. falciparum infections in children from Angola, Ghana and Tanzania and found compelling evidence for competition in mixed-strain infections: overall parasite density did not increase with additional strains, and densities of individual chloroquine-sensitive (CQS) and chloroquine-resistant (CQR) strains were reduced in the presence of competitors. We also found that CQR strains exhibited low densities compared with CQS strains (in the absence of chloroquine), which may underlie observed declines of chloroquine resistance in many countries following retirement of chloroquine as a first-line therapy. Our observations support a key role for within-host competition in the evolution of drug-resistant malaria. Malaria control and resistance-management efforts in high-transmission regions may be significantly aided or hindered by the effects of competition in mixed-strain infections. Consideration of within-host dynamics may spur development of novel strategies to minimize resistance while maximizing the benefits of control measures.

  15. Balancing drug resistance and growth rates via compensatory mutations in the Plasmodium falciparum chloroquine resistance transporter.

    PubMed

    Petersen, Ines; Gabryszewski, Stanislaw J; Johnston, Geoffrey L; Dhingra, Satish K; Ecker, Andrea; Lewis, Rebecca E; de Almeida, Mariana Justino; Straimer, Judith; Henrich, Philipp P; Palatulan, Eugene; Johnson, David J; Coburn-Flynn, Olivia; Sanchez, Cecilia; Lehane, Adele M; Lanzer, Michael; Fidock, David A

    2015-07-01

    The widespread use of chloroquine to treat Plasmodium falciparum infections has resulted in the selection and dissemination of variant haplotypes of the primary resistance determinant PfCRT. These haplotypes have encountered drug pressure and within-host competition with wild-type drug-sensitive parasites. To examine these selective forces in vitro, we genetically engineered P. falciparum to express geographically diverse PfCRT haplotypes. Variant alleles from the Philippines (PH1 and PH2, which differ solely by the C72S mutation) both conferred a moderate gain of chloroquine resistance and a reduction in growth rates in vitro. Of the two, PH2 showed higher IC50 values, contrasting with reduced growth. Furthermore, a highly mutated pfcrt allele from Cambodia (Cam734) conferred moderate chloroquine resistance and enhanced growth rates, when tested against wild-type pfcrt in co-culture competition assays. These three alleles mediated cross-resistance to amodiaquine, an antimalarial drug widely used in Africa. Each allele, along with the globally prevalent Dd2 and 7G8 alleles, rendered parasites more susceptible to lumefantrine, the partner drug used in the leading first-line artemisinin-based combination therapy. These data reveal ongoing region-specific evolution of PfCRT that impacts drug susceptibility and relative fitness in settings of mixed infections, and raise important considerations about optimal agents to treat chloroquine-resistant malaria.

  16. Plasmodium falciparum var genes expressed in children with severe malaria encode CIDRα1 domains.

    PubMed

    Jespersen, Jakob S; Wang, Christian W; Mkumbaye, Sixbert I; Minja, Daniel Tr; Petersen, Bent; Turner, Louise; Petersen, Jens Ev; Lusingu, John Pa; Theander, Thor G; Lavstsen, Thomas

    2016-01-01

    Most severe Plasmodium falciparum infections are experienced by young children. Severe symptoms are precipitated by vascular sequestration of parasites expressing a particular subset of the polymorphic P. falciparum erythrocyte membrane protein 1 (PfEMP1) adhesion molecules. Parasites binding human endothelial protein C receptor (EPCR) through the CIDRα1 domain of certain PfEMP1 were recently associated with severe malaria in children. However, it has remained unclear to which extend the EPCR-binding CIDRα1 domains epitomize PfEMP1 expressed in severe malaria. Here, we characterized the near full-length transcripts dominating the var transcriptome in children with severe malaria and found that the only common feature of the encoded PfEMP1 was CIDRα1 domains. Such genes were highly and dominantly expressed in both children with severe malarial anaemia and cerebral malaria. These observations support the hypothesis that the CIDRα1-EPCR interaction is key to the pathogenesis of severe malaria and strengthen the rationale for pursuing a vaccine or adjunctive treatment aiming at inhibiting or reducing the damaging effects of this interaction.

  17. Transcriptomic evidence for modulation of host inflammatory responses during febrile Plasmodium falciparum malaria

    PubMed Central

    Tran, Tuan M.; Jones, Marcus B.; Ongoiba, Aissata; Bijker, Else M.; Schats, Remko; Venepally, Pratap; Skinner, Jeff; Doumbo, Safiatou; Quinten, Edwin; Visser, Leo G.; Whalen, Elizabeth; Presnell, Scott; O’Connell, Elise M.; Kayentao, Kassoum; Doumbo, Ogobara K.; Chaussabel, Damien; Lorenzi, Hernan; Nutman, Thomas B.; Ottenhoff, Tom H. M.; Haks, Mariëlle C.; Traore, Boubacar; Kirkness, Ewen F.; Sauerwein, Robert W.; Crompton, Peter D.

    2016-01-01

    Identifying molecular predictors and mechanisms of malaria disease is important for understanding how Plasmodium falciparum malaria is controlled. Transcriptomic studies in humans have so far been limited to retrospective analysis of blood samples from clinical cases. In this prospective, proof-of-principle study, we compared whole-blood RNA-seq profiles at pre-and post-infection time points from Malian adults who were either asymptomatic (n = 5) or febrile (n = 3) during their first seasonal PCR-positive P. falciparum infection with those from malaria-naïve Dutch adults after a single controlled human malaria infection (n = 5). Our data show a graded activation of pathways downstream of pro-inflammatory cytokines, with the highest activation in malaria-naïve Dutch individuals and significantly reduced activation in malaria-experienced Malians. Newly febrile and asymptomatic infections in Malians were statistically indistinguishable except for genes activated by pro-inflammatory cytokines. The combined data provide a molecular basis for the development of a pyrogenic threshold as individuals acquire immunity to clinical malaria. PMID:27506615

  18. Parasite Sequestration in Plasmodium falciparum Malaria: Spleen and Antibody Modulation of Cytoadherence of Infected Erythrocytes

    NASA Astrophysics Data System (ADS)

    David, Peter H.; Hommel, Marcel; Miller, Louis H.; Udeinya, Iroka J.; Oligino, Lynette D.

    1983-08-01

    Sequestration, the adherence of infected erythrocytes containing late developmental stages of the parasite (trophozoites and schizonts) to the endothelium of capillaries and venules, is characteristic of Plasmodium falciparum infections. We have studied two host factors, the spleen and antibody, that influence sequestration of P. falciparum in the squirrel monkey. Sequestration of trophozoite/schizont-infected erythrocytes that occurs in intact animals is reduced in splenectomized animals; in vitro, when infected blood is incubated with monolayers of human melanoma cells, trophozoite/schizont-infected erythrocytes from intact animals but not from splenectomized animals bind to the melanoma cells. The switch in cytoadherence characteristics of the infected erythrocytes from nonbinding to binding occurs with a cloned parasite. Immune serum can inhibit and reverse in vitro binding to melanoma cells of infected erythrocytes from intact animals. Similarly, antibody can reverse in vivo sequestration as shown by the appearance of trophozoite/schizont-infected erythrocytes in the peripheral blood of an intact animal after inoculation with immune serum. These results indicate that the spleen modulates the expression of parasite alterations of the infected erythrocyte membrane responsible for sequestration and suggest that the prevention and reversal of sequestration could be one of the effector mechanisms involved in antibody-mediated protection against P. falciparum malaria.

  19. Transcriptomic evidence for modulation of host inflammatory responses during febrile Plasmodium falciparum malaria.

    PubMed

    Tran, Tuan M; Jones, Marcus B; Ongoiba, Aissata; Bijker, Else M; Schats, Remko; Venepally, Pratap; Skinner, Jeff; Doumbo, Safiatou; Quinten, Edwin; Visser, Leo G; Whalen, Elizabeth; Presnell, Scott; O'Connell, Elise M; Kayentao, Kassoum; Doumbo, Ogobara K; Chaussabel, Damien; Lorenzi, Hernan; Nutman, Thomas B; Ottenhoff, Tom H M; Haks, Mariëlle C; Traore, Boubacar; Kirkness, Ewen F; Sauerwein, Robert W; Crompton, Peter D

    2016-01-01

    Identifying molecular predictors and mechanisms of malaria disease is important for understanding how Plasmodium falciparum malaria is controlled. Transcriptomic studies in humans have so far been limited to retrospective analysis of blood samples from clinical cases. In this prospective, proof-of-principle study, we compared whole-blood RNA-seq profiles at pre-and post-infection time points from Malian adults who were either asymptomatic (n = 5) or febrile (n = 3) during their first seasonal PCR-positive P. falciparum infection with those from malaria-naïve Dutch adults after a single controlled human malaria infection (n = 5). Our data show a graded activation of pathways downstream of pro-inflammatory cytokines, with the highest activation in malaria-naïve Dutch individuals and significantly reduced activation in malaria-experienced Malians. Newly febrile and asymptomatic infections in Malians were statistically indistinguishable except for genes activated by pro-inflammatory cytokines. The combined data provide a molecular basis for the development of a pyrogenic threshold as individuals acquire immunity to clinical malaria. PMID:27506615

  20. Within-host competition and drug resistance in the human malaria parasite Plasmodium falciparum.

    PubMed

    Bushman, Mary; Morton, Lindsay; Duah, Nancy; Quashie, Neils; Abuaku, Benjamin; Koram, Kwadwo A; Dimbu, Pedro Rafael; Plucinski, Mateusz; Gutman, Julie; Lyaruu, Peter; Kachur, S Patrick; de Roode, Jacobus C; Udhayakumar, Venkatachalam

    2016-03-16

    Infections with the malaria parasite Plasmodium falciparum typically comprise multiple strains, especially in high-transmission areas where infectious mosquito bites occur frequently. However, little is known about the dynamics of mixed-strain infections, particularly whether strains sharing a host compete or grow independently. Competition between drug-sensitive and drug-resistant strains, if it occurs, could be a crucial determinant of the spread of resistance. We analysed 1341 P. falciparum infections in children from Angola, Ghana and Tanzania and found compelling evidence for competition in mixed-strain infections: overall parasite density did not increase with additional strains, and densities of individual chloroquine-sensitive (CQS) and chloroquine-resistant (CQR) strains were reduced in the presence of competitors. We also found that CQR strains exhibited low densities compared with CQS strains (in the absence of chloroquine), which may underlie observed declines of chloroquine resistance in many countries following retirement of chloroquine as a first-line therapy. Our observations support a key role for within-host competition in the evolution of drug-resistant malaria. Malaria control and resistance-management efforts in high-transmission regions may be significantly aided or hindered by the effects of competition in mixed-strain infections. Consideration of within-host dynamics may spur development of novel strategies to minimize resistance while maximizing the benefits of control measures. PMID:26984625

  1. Hemoglobinopathies: Slicing the Gordian Knot of Plasmodium falciparum Malaria Pathogenesis

    PubMed Central

    Taylor, Steve M.; Cerami, Carla; Fairhurst, Rick M.

    2013-01-01

    Plasmodium falciparum malaria kills over 500,000 children every year and has been a scourge of humans for millennia. Owing to the co-evolution of humans and P. falciparum parasites, the human genome is imprinted with polymorphisms that not only confer innate resistance to falciparum malaria, but also cause hemoglobinopathies. These genetic traits—including hemoglobin S (HbS), hemoglobin C (HbC), and α-thalassemia—are the most common monogenic human disorders and can confer remarkable degrees of protection from severe, life-threatening falciparum malaria in African children: the risk is reduced 70% by homozygous HbC and 90% by heterozygous HbS (sickle-cell trait). Importantly, this protection is principally present for severe disease and largely absent for P. falciparum infection, suggesting that these hemoglobinopathies specifically neutralize the parasite's in vivo mechanisms of pathogenesis. These hemoglobin variants thus represent a “natural experiment” to identify the cellular and molecular mechanisms by which P. falciparum produces clinical morbidity, which remain partially obscured due to the complexity of interactions between this parasite and its human host. Multiple lines of evidence support a restriction of parasite growth by various hemoglobinopathies, and recent data suggest this phenomenon may result from host microRNA interference with parasite metabolism. Multiple hemoglobinopathies mitigate the pathogenic potential of parasites by interfering with the export of P. falciparum erythrocyte membrane protein 1 (PfEMP1) to the surface of the host red blood cell. Few studies have investigated their effects upon the activation of the innate and adaptive immune systems, although recent murine studies suggest a role for heme oxygenase-1 in protection. Ultimately, the identification of mechanisms of protection and pathogenesis can inform future therapeutics and preventive measures. Hemoglobinopathies slice the “Gordian knot” of host and parasite

  2. Long-term persistence of sterile immunity in a volunteer immunized with X-irradiated Plasmodium falciparum sporozoites.

    PubMed

    Edelman, R; Hoffman, S L; Davis, J R; Beier, M; Sztein, M B; Losonsky, G; Herrington, D A; Eddy, H A; Hollingdale, M R; Gordon, D M

    1993-10-01

    Three volunteers were immunized by repeated exposure to the bites of Plasmodium falciparum-infected, X-irradiated mosquitoes to characterize immunologic responses and duration of protective immunity. A primary series of immunizations had been shown previously to induce sterile immunity in these volunteers against sporozoite-induced P. falciparum malaria. In the current study, antibodies to sporozoites circulated at high levels for at least 9-12 months after the volunteers were administered booster bites from X-irradiated infective mosquitoes. One volunteer challenged a second time with P. falciparum 9 months after his last immunization was again shown to be protected, whereas all 5 control subjects developed patent infections. These results set a new standard for persistence of sterile immunity against experimental P. falciparum infection.

  3. Plasmodium falciparum Histidine-Rich Protein II Compromises Brain Endothelial Barriers and May Promote Cerebral Malaria Pathogenesis

    PubMed Central

    Pal, Priya; Daniels, Brian P.; Oskman, Anna; Diamond, Michael S.; Klein, Robyn S.

    2016-01-01

    ABSTRACT Cerebral malaria (CM) is a disease of the vascular endothelium caused by Plasmodium falciparum. It is characterized by parasite sequestration, inflammatory cytokine production, and vascular leakage. A distinguishing feature of P. falciparum infection is parasite production and secretion of histidine-rich protein II (HRPII). Plasma HRPII is a diagnostic and prognostic marker for falciparum malaria. We demonstrate that disruption of a human cerebral microvascular endothelial barrier by P. falciparum-infected erythrocytes depends on expression of HRPII. Purified recombinant or native HRPII can recapitulate these effects. HRPII action occurs via activation of the inflammasome, resulting in decreased integrity of tight junctions and increased endothelial permeability. We propose that HRPII is a virulence factor that may contribute to cerebral malaria by compromising endothelial barrier integrity within the central nervous system. PMID:27273825

  4. Plasmodium falciparum isolates from Angola show the StctVMNT haplotype in the pfcrt gene

    PubMed Central

    2010-01-01

    Background Effective treatment remains a mainstay of malaria control, but it is unfortunately strongly compromised by drug resistance, particularly in Plasmodium falciparum, the most important human malaria parasite. Although P. falciparum chemoresistance is well recognized all over the world, limited data are available on the distribution and prevalence of pfcrt and pfmdr1 haplotypes that mediate resistance to commonly used drugs and that show distinct geographic differences. Methods Plasmodium falciparum-infected blood samples collected in 2007 at four municipalities of Luanda, Angola, were genotyped using PCR and direct DNA sequencing. Single nucleotide polymorphisms in the P. falciparum pfcrt and pfmdr1 genes were assessed and haplotype prevalences were determined. Results and Discussion The most prevalent pfcrt haplotype was StctVMNT (representing amino acids at codons 72-76). This result was unexpected, since the StctVMNT haplotype has previously been seen mainly in parasites from South America and India. The CVIET, CVMNT and CVINT drug-resistance haplotypes were also found, and one previously undescribed haplotype (CVMDT) was detected. Regarding pfmdr1, the most prevalent haplotype was YEYSNVD (representing amino acids at codons 86, 130, 184, 1034, 1042, 1109 and 1246). Wild haplotypes for pfcrt and pfmdr1 were uncommon; 3% of field isolates harbored wild type pfcrt (CVMNK), whereas 21% had wild type pfmdr1 (NEYSNVD). The observed predominance of the StctVMNT haplotype in Angola could be a result of frequent travel between Brazil and Angola citizens in the context of selective pressure of heavy CQ use. Conclusions The high prevalence of the pfcrt SVMNT haplotype and the pfmdr1 86Y mutation confirm high-level chloroquine resistance and might suggest reduced efficacy of amodiaquine in Angola. Further studies must be encouraged to examine the in vitro sensitivity of pfcrt SVMNT parasites to artesunate and amodiaquine for better conclusive data. PMID:20565881

  5. Infants' Peripheral Blood Lymphocyte Composition Reflects Both Maternal and Post-Natal Infection with Plasmodium falciparum.

    PubMed

    Nouatin, Odilon; Gbédandé, Komi; Ibitokou, Samad; Vianou, Bertin; Houngbegnon, Parfait; Ezinmegnon, Sem; Borgella, Sophie; Akplogan, Carine; Cottrell, Gilles; Varani, Stefania; Massougbodji, Achille; Moutairou, Kabirou; Troye-Blomberg, Marita; Deloron, Philippe; Luty, Adrian J F; Fievet, Nadine

    2015-01-01

    Maternal parasitoses modulate fetal immune development, manifesting as altered cellular immunological activity in cord blood that may be linked to enhanced susceptibility to infections in early life. Plasmodium falciparum typifies such infections, with distinct placental infection-related changes in cord blood exemplified by expanded populations of parasite antigen-specific regulatory T cells. Here we addressed whether such early-onset cellular immunological alterations persist through infancy. Specifically, in order to assess the potential impacts of P. falciparum infections either during pregnancy or during infancy, we quantified lymphocyte subsets in cord blood and in infants' peripheral blood during the first year of life. The principal age-related changes observed, independent of infection status, concerned decreases in the frequencies of CD4+, NKdim and NKT cells, whilst CD8+, Treg and Teff cells' frequencies increased from birth to 12 months of age. P. falciparum infections present at delivery, but not those earlier in gestation, were associated with increased frequencies of Treg and CD8+ T cells but fewer CD4+ and NKT cells during infancy, thus accentuating the observed age-related patterns. Overall, P. falciparum infections arising during infancy were associated with a reversal of the trends associated with maternal infection i.e. with more CD4+ cells, with fewer Treg and CD8+ cells. We conclude that maternal P. falciparum infection at delivery has significant and, in some cases, year-long effects on the composition of infants' peripheral blood lymphocyte populations. Those effects are superimposed on separate and independent age- as well as infant infection-related alterations that, respectively, either match or run counter to them. PMID:26580401

  6. Misclassification of Plasmodium infections by conventional microscopy and the impact of remedial training on the proficiency of laboratory technicians in species identification

    PubMed Central

    2013-01-01

    Background Malaria diagnosis is largely dependent on the demonstration of parasites in stained blood films by conventional microscopy. Accurate identification of the infecting Plasmodium species relies on detailed examination of parasite morphological characteristics, such as size, shape, pigment granules, besides the size and shape of the parasitized red blood cells and presence of cell inclusions. This work explores misclassifications of four Plasmodium species by conventional microscopy relative to the proficiency of microscopists and morphological characteristics of the parasites on Giemsa-stained blood films. Case description Ten-day malaria microscopy remedial courses on parasite detection, species identification and parasite counting were conducted for public health and research laboratory personnel. Proficiency in species identification was assessed at the start (pre) and the end (post) of each course using known blood films of Plasmodium falciparum, Plasmodium malariae, Plasmodium ovale and Plasmodium vivax infections with densities ranging from 1,000 to 30,000 parasites/μL. Outcomes were categorized as false negative, positive without speciation, P. falciparum, P. malariae, P. ovale, P. vivax and mixed infections. Discussion and evaluation Reported findings are based on 1,878 P. falciparum, 483 P. malariae, 581 P. ovale and 438 P. vivax cumulative results collated from 2008 to 2010 remedial courses. Pre-training false negative and positive misclassifications without speciation were significantly lower on P. falciparum infections compared to non-falciparum infections (p < 0.0001). Post-training misclassifications decreased significantly compared to pre- training misclassifications which in turn led to significant improvements in the identification of the four species. However, P. falciparum infections were highly misclassified as mixed infections, P. ovale misclassified as P. vivax and P. vivax similarly misclassified as P. ovale (p < 0

  7. Complement activation in primiparous women from a malaria endemic area is associated with reduced birthweight.

    PubMed

    Khattab, A; Kremsner, P G; Meri, S

    2013-02-01

    The hallmark of placental malaria (PM) due to Plasmodium falciparum infection is the accumulation of mature-stage parasites, monocytes and macrophages in the maternal vascular bed of the placenta. The mechanisms leading to morbidity and mortality in PM are incompletely understood. However, an inflammatory response in the placenta has been related to both severe anemia in the mother and low birthweight (<2500 g) in the newborn. In this study we analyzed whether complement activation as a mediator of inflammation could contribute to poor pregnancy outcome in PM. The concentrations of the soluble terminal complement complex (TCC) were measured as an indicator of complement activation in placental, cord and peripheral blood samples from 146 women from a malaria endemic area. Placental and cord plasma samples of primiparous women, a group vulnerable to PM, showed significantly higher levels of TCC than multiparous women. Additionally, in women with malaria history during pregnancy or placental infection by P. falciparum at delivery, the TCC levels in the corresponding placental and cord plasma samples were significantly higher than in the malaria negative group. In multiple regression analysis parity was shown to be the main determinant of TCC levels. Placental plasma samples corresponding to babies weighing less than 2700 g had significantly higher levels of TCC than babies carrying more weight. In conclusion, both primiparity and P. falciparum infection were related to a local increase of complement activation in the placentas. Association between reduced birthweight and higher levels of TCC in placental blood suggests a role for complement activation in influencing the pregnancy outcome in malaria exposed women. PMID:23261341

  8. A bedside dipstick method to detect Plasmodium falciparum.

    PubMed

    Shah, Ira; Deshmukh, C T

    2004-11-01

    We conducted this study to determine efficacy of Parasight-F (an HRP-II antigen dipstick method to detect P. Falciparum) in children. A total of 30 children were enrolled in the age group of 2 months to 12 years whose peripheral smear showed asexual forms of Plasmodium falciparum. All patients were tested for presence of HRP-II antigen of Plasmodium falciparum in their blood by the Parasight-F dipstick test by either an EDTA sample or a finger prick blood sample. The sensitivity of Parasight-F was 83.3 % However, the sensitivity of Parasight-F to detect Plasmodium Falciparum in case of mixed Plasmodium (Vivax + Falciparum) infection was only 25 %. Also, all patients less than 6 months of age had a negative Parasight-F test. Parasitic index, prior treatment with antimalarials or severity of Falciparum malaria have no effect on the sensitivity of Parasight-F test. We conclude that Parasight-F is an effective tool for diagnosis of Plasmoduim falciparum malaria in children. PMID:15591666

  9. Chickens treated with a nitric oxide inhibitor became more resistant to Plasmodium gallinaceum infection due to reduced anemia, thrombocytopenia and inflammation

    PubMed Central

    2013-01-01

    Malaria is a serious infectious disease caused by parasites of the Plasmodium genus that affect different vertebrate hosts. Severe malaria leads to host death and involves different pathophysiological phenomena such as anemia, thrombocytopenia and inflammation. Nitric oxide (NO) is an important effector molecule in this disease, but little is known about its role in avian malaria models. Plasmodium gallinaceum- infected chickens were treated with aminoguanidine (AG), an inhibitor of inducible nitric oxide synthase, to observe the role of NO in the pathogenesis of this avian model. AG increased the survival of chickens, but also induced higher parasitemia. Treated chickens demonstrated reduced anemia and thrombocytopenia. Moreover, erythrocytes at different stages of maturation, heterophils, monocytes and thrombocytes were infected by Plasmodium gallinaceum and animals presented a generalized leucopenia. Activated leukocytes and thrombocytes with elongated double nuclei were observed in chickens with higher parasitemia; however, eosinophils were not involved in the infection. AG reduced levels of hemozoin in the spleen and liver, indicating lower inflammation. Taken together, the results suggest that AG reduced anemia, thrombocytopenia and inflammation, explaining the greater survival rate of the treated chickens. PMID:23398940

  10. Plasmodium falciparum: growth response to potassium channel blocking compounds.

    PubMed

    Waller, Karena L; Kim, Kami; McDonald, Thomas V

    2008-11-01

    Potassium channels are essential for cell survival and regulate the cell membrane potential and electrochemical gradient. During its lifecycle, Plasmodium falciparum parasites must rapidly adapt to dramatically variant ionic conditions within the mosquito mid-gut, the hepatocyte and red blood cell (RBC) cytosols, and the human circulatory system. To probe the participation of K(+) channels in parasite viability, growth response assays were performed in which asexual stage P. falciparum parasites were cultured in the presence of various Ca(2+)-activated K(+) channel blocking compounds. These data describe the novel anti-malarial effects of bicuculline methiodide and tubocurarine chloride and the novel lack of effect of apamine and verruculogen. Taken together, the data herein imply the presence of K(+) channels, or other parasite-specific targets, in P. falciparum-infected RBCs that are sensitive to blockade with Ca(2+)-activated K(+) channel blocking compounds. PMID:18703053

  11. Plasmodium Falciparum Malaria

    PubMed Central

    Schmidt, John A.; Udeinya, Iroka J.; Leech, James H.; Hay, Robert J.; Aikawa, Masamichi; Barnwell, John; Green, Ira; Miller, Louis H.

    1982-01-01

    Erythrocytes infected with Plasmodium falciparum trophozoites and schizonts are not seen in the peripheral circulation because they attach to venular endothelium via knoblike structures on the infected erythrocyte membrane. We have recently shown that erythrocytes containing P. falciparum trophozoites and schizonts likewise attach to cultured human venous endothelial cells via knobs. In search of a more practical target cell for large scale binding studies designed to characterize and isolate the knob ligand, we tested various normal cells and continuous cell lines for their ability to bind P. falciparum-infected erythrocytes. Of the 18 cell types tested, binding of infected erythrocytes was observed to a human amelanotic melanoma cell line and amnion epithelial cells as well as to human aortic and umbilical vein endothelial cells. 96-100% of amelanotic melanoma cells bound 17±4 (±1 SEM) infected erythrocytes per positive cell, whereas fewer endothelial cells (4-59%) and amnion epithelial cells (8-19%) were capable of binding 12±5 and 4±1 infected erythrocytes per positive cell, respectively. Further studies designed to compare the mechanism of binding to the amelanotic melanoma cell line and endothelial cells showed the following results. First, that adhesion of infected erythrocytes to these two cell types was parasite stage-specific in that only erythrocytes containing late ring forms, trophozoites, and schizonts bound. Erythrocytes containing early ring forms, which do not attach to venular endothelium in vivo, did not bind to either cell type. Second, erythrocytes infected with trophozoites and schizonts of P. vivax or a knobless strain of P. falciparum, both of which continue to circulate in vivo, did not bind to either target cell type. Third, transmission electron microscopy showed that infected erythrocytes attached to the amelanotic melanoma cells via knobs. We conclude that cultured human endothelial cells and an amelanotic melanoma cell line share

  12. Reduced erythrocyte susceptibility and increased host clearance of young parasites slows Plasmodium growth in a murine model of severe malaria

    NASA Astrophysics Data System (ADS)

    Khoury, David S.; Cromer, Deborah; Best, Shannon E.; James, Kylie R.; Sebina, Ismail; Haque, Ashraful; Davenport, Miles P.

    2015-05-01

    The best correlate of malaria severity in human Plasmodium falciparum (Pf) infection is the total parasite load. Pf-infected humans could control parasite loads by two mechanisms, either decreasing parasite multiplication, or increasing parasite clearance. However, few studies have directly measured these two mechanisms in vivo. Here, we have directly quantified host clearance of parasites during Plasmodium infection in mice. We transferred labelled red blood cells (RBCs) from Plasmodium infected donors into uninfected and infected recipients, and tracked the fate of donor parasites by frequent blood sampling. We then applied age-based mathematical models to characterise parasite clearance in the recipient mice. Our analyses revealed an increased clearance of parasites in infected animals, particularly parasites of a younger developmental stage. However, the major decrease in parasite multiplication in infected mice was not mediated by increased clearance alone, but was accompanied by a significant reduction in the susceptibility of RBCs to parasitisation.

  13. Prevalence of Plasmodium falciparum transmission reducing immunity among primary school children in a malaria moderate transmission region in Zimbabwe.

    PubMed

    Paul, Noah H; Vengesai, Arthur; Mduluza, Takafira; Chipeta, James; Midzi, Nicholas; Bansal, Geetha P; Kumar, Nirbhay

    2016-11-01

    Malaria continues to cause alarming morbidity and mortality in more than 100 countries worldwide. Antigens in the various life cycle stages of malaria parasites are presented to the immune system during natural infection and it is widely recognized that after repeated malaria exposure, adults develop partially protective immunity. Specific antigens of natural immunity represent among the most important targets for the development of malaria vaccines. Immunity against the transmission stages of the malaria parasite represents an important approach to reduce malaria transmission and is believed to become an important tool for gradual elimination of malaria. Development of immunity against Plasmodium falciparum sexual stages was evaluated in primary school children aged 6-16 years in Makoni district of Zimbabwe, an area of low to modest malaria transmission. Malaria infection was screened by microscopy, rapid diagnostic tests and finally using nested PCR. Plasma samples were tested for antibodies against recombinant Pfs48/45 and Pfs47 by ELISA. Corresponding serum samples were used to test for P. falciparum transmission reducing activity in Anopheles stephensi and An. gambiae mosquitoes using the membrane feeding assay. The prevalence of malaria diagnosed by rapid diagnostic test kit (Paracheck)™ was 1.7%. However, of the randomly tested blood samples, 66% were positive by nested PCR. ELISA revealed prevalence (64% positivity at 1:500 dilution, in randomly selected 66 plasma samples) of antibodies against recombinant Pfs48/45 (mean A 405nm=0.53, CI=0.46-0.60) and Pfs47 (mean A405nm=0.91, CI=0.80-1.02); antigens specific to the sexual stages. The mosquito membrane feeding assay demonstrated measurable transmission reducing ability of the samples that were positive for Pfs48/45 antibodies by ELISA. Interestingly, 3 plasma samples revealed enhancement of infectivity of P. falciparum in An. stephensi mosquitoes. These studies revealed the presence of antibodies with

  14. Tracing the origins and signatures of selection of antifolate resistance in island populations of Plasmodium falciparum

    PubMed Central

    2010-01-01

    Background Resistance of the malaria parasite Plasmodium falciparum to sulfadoxine-pyrimethamine (SP) has evolved worldwide. In the archipelago of São Tomé and Principe (STP), West Africa, although SP resistance is highly prevalent the drug is still in use in particular circumstances. To address the evolutionary origins of SP resistance in these islands, we genotyped point mutations at P. falciparum dhfr and dhps genes and analysed microsatellites flanking those genes. Methods Blood samples were collected in July and December 2004 in three localities of São Tomé Island and one in Principe Island. Species-specific nested-PCR was used to identify P. falciparum infected samples. Subsequently, SNPs at the dhfr and dhps genes were identified through PCR-RFLP. Isolates were also analysed for three microsatellite loci flanking the dhfr gene, three loci flanking dhps and four loci located at putative neutral genomic regions. Results An increase of resistance-associated mutations at dhfr and dhps was observed, in particular for the dhfr/dhps quintuple mutant, associated with clinical SP failure. Analysis of flanking microsatellites suggests multiple independent introductions for dhfr and dhps mutant haplotypes, possibly from West Africa. A reduced genetic diversity and increased differentiation at flanking microsatellites when compared to neutral loci is consistent with a selective sweep for resistant alleles at both loci. Conclusions This study provides additional evidence for the crucial role of gene flow and drug selective pressures in the rapid spread of SP resistance in P. falciparum populations, from only a few mutation events giving rise to resistance-associated mutants. It also highlights the importance of human migration in the spread of drug resistant malaria parasites, as the distance between the islands and mainland is not consistent with mosquito-mediated parasite dispersal. PMID:20534146

  15. Profoundly Reduced CD1c+ Myeloid Dendritic Cell HLA-DR and CD86 Expression and Increased Tumor Necrosis Factor Production in Experimental Human Blood-Stage Malaria Infection

    PubMed Central

    Minigo, Gabriela; Burel, Julie; Tipping, Peta E.; Piera, Kim A.; Amante, Fiona H.; Engwerda, Christian R.; Good, Michael F.; Doolan, Denise L.; Anstey, Nicholas M.; McCarthy, James S.; Woodberry, Tonia

    2016-01-01

    Dendritic cells (DCs) are sentinels of the immune system that uniquely prime naive cells and initiate adaptive immune responses. CD1c (BDCA-1) myeloid DCs (CD1c+ mDCs) highly express HLA-DR, have a broad Toll-like receptor (TLR) repertoire, and secrete immune modulatory cytokines. To better understand immune responses to malaria, CD1c+ mDC maturation and cytokine production were examined in healthy volunteers before and after experimental intravenous Plasmodium falciparum infection with 150- or 1,800-parasite-infected red blood cells (pRBCs). After either dose, CD1c+ mDCs significantly reduced HLA-DR expression in prepatent infections. Circulating CD1c+ mDCs did not upregulate HLA-DR after pRBC or TLR ligand stimulation and exhibited reduced CD86 expression. At peak parasitemia, CD1c+ mDCs produced significantly more tumor necrosis factor (TNF), whereas interleukin-12 (IL-12) production was unchanged. Interestingly, only the 1,800-pRBC dose caused a reduction in the circulating CD1c+ mDC count with evidence of apoptosis. The 1,800-pRBC dose produced no change in T cell IFN-γ or IL-2 production at peak parasitemia or at 3 weeks posttreatment. Overall, CD1c+ mDCs are compromised by P. falciparum exposure, with impaired HLA-DR and CD86 expression, and have an increased capacity for TNF but not IL-12 production. A first prepatent P. falciparum infection is sufficient to modulate CD1c+ mDC responsiveness, likely contributing to hampered effector T cell cytokine responses and assisting parasite immune evasion. PMID:26902728

  16. Profoundly Reduced CD1c+ Myeloid Dendritic Cell HLA-DR and CD86 Expression and Increased Tumor Necrosis Factor Production in Experimental Human Blood-Stage Malaria Infection.

    PubMed

    Loughland, Jessica R; Minigo, Gabriela; Burel, Julie; Tipping, Peta E; Piera, Kim A; Amante, Fiona H; Engwerda, Christian R; Good, Michael F; Doolan, Denise L; Anstey, Nicholas M; McCarthy, James S; Woodberry, Tonia

    2016-05-01

    Dendritic cells (DCs) are sentinels of the immune system that uniquely prime naive cells and initiate adaptive immune responses. CD1c (BDCA-1) myeloid DCs (CD1c(+) mDCs) highly express HLA-DR, have a broad Toll-like receptor (TLR) repertoire, and secrete immune modulatory cytokines. To better understand immune responses to malaria, CD1c(+) mDC maturation and cytokine production were examined in healthy volunteers before and after experimental intravenous Plasmodium falciparum infection with 150- or 1,800-parasite-infected red blood cells (pRBCs). After either dose, CD1c(+) mDCs significantly reduced HLA-DR expression in prepatent infections. Circulating CD1c(+) mDCs did not upregulate HLA-DR after pRBC or TLR ligand stimulation and exhibited reduced CD86 expression. At peak parasitemia, CD1c(+) mDCs produced significantly more tumor necrosis factor (TNF), whereas interleukin-12 (IL-12) production was unchanged. Interestingly, only the 1,800-pRBC dose caused a reduction in the circulating CD1c(+) mDC count with evidence of apoptosis. The 1,800-pRBC dose produced no change in T cell IFN-γ or IL-2 production at peak parasitemia or at 3 weeks posttreatment. Overall, CD1c(+) mDCs are compromised by P. falciparum exposure, with impaired HLA-DR and CD86 expression, and have an increased capacity for TNF but not IL-12 production. A first prepatent P. falciparum infection is sufficient to modulate CD1c(+) mDC responsiveness, likely contributing to hampered effector T cell cytokine responses and assisting parasite immune evasion.

  17. Therapeutic response of multidrug-resistant Plasmodium falciparum and P. vivax to chloroquine and sulfadoxine-pyrimethamine in southern Papua, Indonesia.

    PubMed

    Ratcliff, A; Siswantoro, H; Kenangalem, E; Wuwung, M; Brockman, A; Edstein, M D; Laihad, F; Ebsworth, E P; Anstey, N M; Tjitra, E; Price, R N

    2007-04-01

    To determine the level of antimalarial drug resistance in southern Papua, Indonesia, we assessed the therapeutic efficacy of chloroquine plus sulfadoxine-pyrimethamine (CQ+SP) for Plasmodium falciparum infections as well as CQ monotherapy for P. vivax infections. Patients with P. falciparum failing therapy were re-treated with unsupervised quinine+/-doxycycline therapy and those with P. vivax with either unsupervised quinine+/-doxycycline or amodiaquine. In total, 143 patients were enrolled in the study (103 treated with CQ+SP and 40 with CQ). Early treatment failures occurred in four patients (4%) with P. falciparum and six patients (15%) with P. vivax. The failure rate by Day 28 for P. vivax was 65% (95% CI 49-81). After PCR correction for re-infections, the Day 42 recrudescence rate for P. falciparum infections was 48% (95% CI 31-65). Re-treatment with unsupervised quinine+/-doxycycline resulted in further recurrence of malaria in 48% (95% CI 31-65) of P. falciparum infections and 70% (95% CI 37-100) of P. vivax infections. Eleven patients with recurrent P. vivax were re-treated with amodiaquine; there were no early or late treatment failures. In southern Papua, a high prevalence of drug resistance of P. falciparum and P. vivax exists both to first- and second-line therapies. Preliminary data indicate that amodiaquine retains superior efficacy compared with CQ for CQ-resistant P. vivax.

  18. Atovaquone-Proguanil Remains a Potential Stopgap Therapy for Multidrug-Resistant Plasmodium falciparum in Areas along the Thai-Cambodian Border.

    PubMed

    Saunders, David L; Chaorattanakawee, Suwanna; Gosi, Panita; Lanteri, Charlotte; Somethy, Sok; Kuntawunginn, Worachet; Ittiverakul, Mali; Chann, Soklyda; Gregory, Carrie; Chuor, Char Meng; Prom, Satharath; Spring, Michele D; Lon, Chanthap

    2016-03-01

    Our recent report of dihydroartemisinin-piperaquine failure to treat Plasmodium falciparum infections in Cambodia adds new urgency to the search for alternative treatments. Despite dihydroartemisinin-piperaquine failure, and higher piperaquine 50% inhibitory concentrations (IC50s) following reanalysis than those previously reported, P. falciparum remained sensitive to atovaquone (ATQ) in vitro. There were no point mutations in the P. falciparum cytochrome b ATQ resistance gene. Mefloquine, artemisinin, chloroquine, and quinine IC50s remained comparable to those from other recent reports. Atovaquone-proguanil may be a useful stopgap but remains susceptible to developing resistance when used as blood-stage therapy. PMID:26711753

  19. Serum protein concentrations in Plasmodium falciparum malaria.

    PubMed

    Graninger, W; Thalhammer, F; Hollenstein, U; Zotter, G M; Kremsner, P G

    1992-12-01

    In patients with uncomplicated Plasmodium falciparum infection cytokine-mediated serum protein levels of C-reactive protein (CRP), coeruloplasmin (COE), beta 2-microglobulin (B2M), alpha 1-acid glycoprotein (AAG), alpha 1-antitrypsin (AAT), haptoglobin (HPT), prealbumin (PRE), retinol binding protein (RBP), albumin (ALB) and transferrin (TRF) were measured in an endemic area of the Amazonian rain forest. Semi-immune (SI) and nonimmune (NI) patients were investigated. In both patient groups the serum concentrations of CRP, COE and B2M were elevated on admission. In addition AAG and AAT concentrations were increased in NI patients compared to control subjects. Significantly lower serum concentrations of HPT, PRE, RBP, ALB and TRF were seen in both patient groups during the acute phase of the disease, and were more pronounced in NI patients. After a 28-day follow-up, AAT and B2M were normal in SI patients but HPT, AAT and B2M were still significantly altered in NI patients.

  20. Maternal-foetal transfer of Plasmodium falciparum and Plasmodium vivax antibodies in a low transmission setting

    PubMed Central

    Charnaud, Sarah C.; McGready, Rose; Herten-Crabb, Asha; Powell, Rosanna; Guy, Andrew; Langer, Christine; Richards, Jack S.; Gilson, Paul R.; Chotivanich, Kesinee; Tsuboi, Takafumi; Narum, David L.; Pimanpanarak, Mupawjay; Simpson, Julie A.; Beeson, James G.; Nosten, François; Fowkes, Freya J. I.

    2016-01-01

    During pregnancy immunolglobulin G (IgG) antibodies are transferred from mother to neonate across the placenta. Studies in high transmission areas have shown transfer of P. falciparum-specific IgG, but the extent and factors influencing maternal-foetal transfer in low transmission areas co-endemic for both P. falciparum and P. vivax are unknown. Pregnant women were screened weekly for Plasmodium infection. Mother-neonate paired serum samples at delivery were tested for IgG to antigens from P. falciparum, P. vivax and other infectious diseases. Antibodies to malarial and non-malarial antigens were highly correlated between maternal and neonatal samples (median [range] spearman ρ = 0.78 [0.57–0.93]), although Plasmodium spp. antibodies tended to be lower in neonates than mothers. Estimated gestational age at last P. falciparum infection, but not P. vivax infection, was positively associated with antibody levels in the neonate (P. falciparum merozoite, spearman ρ median [range] 0.42 [0.33–0.66], PfVAR2CSA 0.69; P. vivax ρ = 0.19 [0.09–0.3]). Maternal-foetal transfer of anti-malarial IgG to Plasmodium spp. antigens occurs in low transmission settings. P. vivax IgG acquisition is not associated with recent exposure unlike P. falciparum IgG, suggesting a difference in acquisition of antibodies. IgG transfer is greatest in the final weeks of pregnancy which has implications for the timing of future malaria vaccination strategies in pregnant women. PMID:26861682

  1. Current clinical efficacy of chloroquine for the treatment of Plasmodium falciparum infections in urban Dar es Salaam, United Republic of Tanzania.

    PubMed Central

    Premji, Z.; Makwaya, C.; Minjas, J. N.

    1999-01-01

    Reported is the use of a 14-day WHO protocol, which takes into account the clinical, parasitological and haematological responses to antimalarial drugs, to determine the efficacy of chloroquine in the treatment of uncomplicated malaria in young children (n = 200) in urban Dar es Salaam. Chloroquine failure was found in 43% of the children. Of these, 12.5% were considered to be early treatment failures and were given a single dose of sulfadoxine-pyrimethamine. Fever subsided in all children treated with sulfadoxine-pyrimethamine and there were no parasitological failures. In addition, children treated with sulfadoxine-pyrimethamine because of early treatment failure with chloroquine had better haematological recovery than the chloroquine-sensitive group. It is concluded that chloroquine can no longer be considered an effective therapy for P. falciparum malaria in young children in Dar es Salaam. PMID:10534897

  2. Social Acceptability and Durability of Two Different House Screening Interventions against Exposure to Malaria Vectors, Plasmodium falciparum Infection, and Anemia in Children in The Gambia, West Africa

    PubMed Central

    Kirby, Matthew J.; Bah, Pateh; Jones, Caroline O. H.; Kelly, Ann H.; Jasseh, Momodou; Lindsay, Steve W.

    2010-01-01

    The social acceptability and durability of two house screening interventions were addressed using focus group discussions, questionnaires, indoor climate measurements, and durability surveys. Participants recognized that screening stopped mosquitoes (79–96%) and other insects (86–98%) entering their houses. These and other benefits were appreciated by significantly more recipients of full screening than users of screened ceilings. Full screened houses were 0.26°C hotter at night (P = 0.05) than houses with screened ceilings and 0.51°C (P < 0.001) hotter than houses with no screening (28.43°C), though only 9% of full screened house users and 17% of screened ceiling users complained about the heat. Although 71% of screened doors and 85% of ceilings had suffered some damage after 12 months, the average number of holes of any size was < 5 for doors and < 7 for ceilings. In conclusion, house screening is a well-appreciated and durable vector control tool. PMID:21036822

  3. Glucose-6-phosphate dehydrogenase status and risk of hemolysis in Plasmodium falciparum-infected African children receiving single-dose primaquine.

    PubMed

    Eziefula, Alice C; Pett, Helmi; Grignard, Lynn; Opus, Salome; Kiggundu, Moses; Kamya, Moses R; Yeung, Shunmay; Staedke, Sarah G; Bousema, Teun; Drakeley, Chris

    2014-08-01

    Glucose-6-phosphate dehydrogenase (G6PD) enzyme function and genotype were determined in Ugandan children with uncomplicated falciparum malaria enrolled in a primaquine trial after exclusion of severe G6PD deficiency by fluorescent spot test. G6PD A- heterozygotes and hemizygotes/homozygotes experienced dose-dependent lower hemoglobin concentrations after treatment. No severe anemia was observed. PMID:24913169

  4. Piperaquine Monotherapy of Drug-Susceptible Plasmodium falciparum Infection Results in Rapid Clearance of Parasitemia but Is Followed by the Appearance of Gametocytemia

    PubMed Central

    Pasay, Cielo J.; Rockett, Rebecca; Sekuloski, Silvana; Griffin, Paul; Marquart, Louise; Peatey, Christopher; Wang, Claire Y. T.; O'Rourke, Peter; Elliott, Suzanne; Baker, Mark; Möhrle, Jörg J.; McCarthy, James S.

    2016-01-01

    Background. Piperaquine, coformulated with dihydroartemisinin, is a component of a widely used artemisinin combination therapy. There is a paucity of data on its antimalarial activity as a single agent. Such data, if available, would inform selection of new coformulations. Methods. We undertook a study in healthy subjects, using the induced blood stage malaria (IBSM) model to test the antimalarial activity of single doses of piperaquine (960, 640, and 480 mg) in 3 cohorts. In a pilot study in the third cohort, gametocyte clearance following administration of 15 mg, or 45 mg or no primaquine was investigated. Results. Parasite clearance over the 48-hour period after piperaquine administration was more rapid in the 960 mg cohort, compared with the 640 mg cohort (parasite reduction ratio, 2951 [95% confidence interval {CI}, 1520–5728] vs 586 [95% CI, 351–978]; P < .001). All 24 subjects developed gametocytemia as determined by pfs25 transcripts. Clearance of pfs25 was significantly faster in those receiving primaquine than in those not receiving primaquine (P < .001). Conclusions. Piperaquine possesses rapid parasite-clearing activity, but monotherapy is followed by the appearance of gametocytemia, which could facilitate the spread of malaria. This new information should be taken into account when developing future antimalarial coformulations. Clinical Trials Registration ACTRN12613000565741. PMID:27056954

  5. Pharmacokinetics and pharmacodynamics of artesunate and dihydroartemisinin following oral treatment in pregnant women with asymptomatic Plasmodium falciparum infections in Kinshasa DRC

    PubMed Central

    2011-01-01

    Background In many malaria-endemic countries, increasing resistance may soon compromise the efficacy of sulphadoxine-pyrimethamine (SP) for intermittent preventative treatment (IPT) of malaria in pregnancy. Artemisinin-based IPT regimens represent a promising potential alternative to SP. Pharmacokinetic and safety data supporting the use of artemisinin derivatives in pregnancy are urgently needed. Methods Subjects included pregnant women with asymptomatic falciparum parasitaemia between 22-26 weeks (n = 13) or 32-36 weeks gestation (n = 13), the same women at three months postpartum, and 25 non-pregnant parasitaemic controls. All subjects received 200 mg orally administered AS. Plasma total and free levels of AS and its active metabolite DHA were determined using a validated LC-MS method. Non-compartmental pharmacokinetic analysis was performed using standard methods. Results All pregnant women delivered live babies. The median birth weight was 3025 grams [range 2130, 3620]; 2 of 26 babies had birth weights less than 2500 grams. Rates of parasite clearance by 12 hours post-dose were high and comparable among the groups. Rapid elimination of AS was observed in all three groups. The 90% CI for the pregnancy:postpartum ratio of geometric means for total and free AUC fell within the pre-specified 0.66 - 1.50 therapeutic equivalence interval. However, more pronounced pharmacokinetic differences were observed between the pregnancy and control subjects, with the 90% CI for the pregnancy:control ratio of geometric means for both total 0.68 (90% CI 0.57-0.81) and free AUC 0.78 (90% CI 0.63-0.95) not fully contained within the 0.66 - 1.50 interval. All subjects cleared parasites rapidly, and there was no difference in the percentage of women who were parasitaemic 12 hours after dosing. Conclusions A single dose of orally administered AS was found to be both effective and without adverse effects in this study of second and third trimester pregnant women in the DRC. Although DHA AUC during pregnancy and postpartum were similar, the AUC for the pregnant group was less than the non-pregnant controls. The findings of this study suggest that additional studies on the pharmacokinetics of AS in pregnant women are needed. Trial Registration ClinicalTrials.gov: NCT00538382 PMID:21352601

  6. ama1 Genes of Sympatric Plasmodium vivax and P. falciparum from Venezuela Differ Significantly in Genetic Diversity and Recombination Frequency

    PubMed Central

    Ord, Rosalynn L.; Tami, Adriana; Sutherland, Colin J.

    2008-01-01

    Background We present the first population genetic analysis of homologous loci from two sympatric human malaria parasite populations sharing the same human hosts, using full-length sequences of ama1 genes from Plasmodium vivax and P. falciparum collected in the Venezuelan Amazon. Methodology/Principal Findings Significant differences between the two species were found in genetic diversity at the ama1 locus, with 18 distinct haplotypes identified among the 73 Pvama1 sequences obtained, compared to 6 unique haplotypes from 30 Pfama1 sequences, giving overall diversity estimates of h = 0.9091, and h = 0.538 respectively. Levels of recombination were also found to differ between the species, with P. falciparum exhibiting very little recombination across the 1.77kb sequence. In contrast, analysis of patterns of nucleotide substitutions provided evidence that polymorphisms in the ama1 gene of both species are maintained by balancing selection, particularly in domain I. The two distinct population structures observed are unlikely to result from different selective forces acting upon the two species, which share both human and mosquito hosts in this setting. Rather, the highly structured P. falciparum population appears to be the result of a population bottleneck, while the much less structured P. vivax population is likely to be derived from an ancient pool of diversity, as reflected in a larger estimate of effective population size for this species. Greatly reduced mosquito transmission in 1997, due to low rainfall prior to the second survey, was associated with far fewer P. falciparum infections, but an increase in P. vivax infections, probably due to hypnozoite activation. Conclusions/Significance The relevance of these findings to putative competitive interactions between these two important human pathogen species is discussed. These results highlight the need for future control interventions to employ strategies targeting each of the parasite species present

  7. Efficacy of dihydroartemisinin-piperaquine for treatment of uncomplicated Plasmodium falciparum and Plasmodium vivax in Cambodia, 2008 to 2010.

    PubMed

    Leang, Rithea; Barrette, Amy; Bouth, Denis Mey; Menard, Didier; Abdur, Rashid; Duong, Socheat; Ringwald, Pascal

    2013-02-01

    We describe here the results of antimalarial therapeutic efficacy studies conducted in Cambodia from 2008 to 2010. A total of 15 studies in four sentinel sites were conducted using dihydroartemisinin-piperaquine (DP) for the treatment of Plasmodium falciparum infection and chloroquine (CQ) and DP for the treatment of P. vivax infection. All studies were performed according to the standard World Health Organization protocol for the assessment of antimalarial treatment efficacy. Among the studies of DP for the treatment of P. falciparum, an increase in treatment failure was observed in the western provinces. In 2010, the PCR-corrected treatment failure rates for DP on day 42 were 25% (95% confidence interval [CI] = 10 to 51%) in Pailin and 10.7% (95% CI = 4 to 23%) in Pursat, while the therapeutic efficacy of DP remained high (100%) in Ratanakiri and Preah Vihear provinces, located in northern and eastern Cambodia. For the studies of P. vivax, the day 28 uncorrected treatment failure rate among patients treated with CQ ranged from 4.4 to 17.4%; DP remained 100% effective in all sites. Further study is required to investigate suspected P. falciparum resistance to piperaquine in western Cambodia; the results of in vitro and molecular studies were not found to support the therapeutic efficacy findings. The emergence of artemisinin resistance in this region has likely put additional pressure on piperaquine. Although DP appears to be an appropriate new first-line treatment for P. vivax in Cambodia, alternative treatments are urgently needed for P. falciparum-infected patients in western Cambodia.

  8. Changes in B Cell Populations and Merozoite Surface Protein-1-Specific Memory B Cell Responses after Prolonged Absence of Detectable P. falciparum Infection

    PubMed Central

    Ayieko, Cyrus; Maue, Alexander C.; Jura, Walter G. Z. O.; Noland, Gregory S.; Ayodo, George; Rochford, Rosemary; John, Chandy C.

    2013-01-01

    Clinical immunity to malaria declines in the absence of repeated parasite exposure. However, little is known about how B cell populations and antigen-specific memory B cells change in the absence of P. falciparum infection. A successful indoor residual insecticide spraying campaign in a highland area of western Kenya, led to an absence of blood-stage P. falciparum infection between March 2007 and April 2008. We assessed memory B cell responses in 45 adults at the beginning (April 2008) and end (April 2009) of a subsequent 12-month period during which none of the adults had evidence of asymptomatic parasitemia or clinical disease. Antibodies and memory B cells to the 42-kDa portion of the merozoite surface protein-1 (MSP-142) were measured using ELISA and ELISPOT assays, respectively. B cell populations were characterized by flow cytometry. From 2008 to 2009, the prevalence of MSP-142-specific memory B cells (45% vs. 55%, respectively, P = 0.32) or antibodies (91% vs. 82%, respectively, P = 0.32) did not differ significantly, although specific individuals did change from positive to negative and vice versa, particularly for memory B cells, suggesting possible low-level undetected parasitemia may have occurred in some individuals. The magnitude of MSP-142-specific memory B cells and levels of antibodies to MSP-142 also did not differ from 2008 to 2009 (P>0.10 for both). However, from 2008 to 2009 the proportions of both class-switched atypical (CD19+IgD-CD27-CD21-IgM-) and class-switched activated (CD19+IgD-CD27+CD21-IgM-) memory B cells decreased (both P<0.001). In contrast, class-switched resting classical memory B cells (CD19+IgD-CD27+CD21+IgM-) increased (P<0.001). In this area of seasonal malaria transmission, a one- year absence of detectable P. falciparum infection was not associated with changes in the prevalence or level of MSP-142 specific memory B cells, but was associated with major changes in overall memory B cell subsets. PMID:23826242

  9. Plasmodium chabaudi-Infected Erythrocytes Adhere to CD36 and Bind to Microvascular Endothelial Cells in an Organ-Specific Way

    PubMed Central

    Mota, Maria M.; Jarra, William; Hirst, Elizabeth; Patnaik, Pradeep K.; Holder, Anthony A.

    2000-01-01

    Adherence of erythrocytes infected with Plasmodium falciparum to microvascular endothelial cells (sequestration) is considered to play an important role in parasite virulence and pathogenesis. However, the real importance of sequestration for infection and disease has never been fully assessed. The absence of an appropriate in vivo model for sequestration has been a major barrier. We have examined the rodent malaria parasite Plasmodium chabaudi chabaudi AS in mice as a potential model. Erythrocytes infected with this parasite adhere in vitro to purified CD36, a critical endothelium receptor for binding P. falciparum-infected erythrocytes. P. c. chabaudi-infected erythrocytes adhere in vitro to endothelial cells in a gamma interferon-dependent manner, suggesting the involvement of additional adhesion molecules in the binding process, as is also the case with P. falciparum-infected cells. Furthermore, plasma or sera from infected and hyperimmune mice, respectively, have the ability to block binding of infected erythrocytes to endothelial cells. In vivo, erythrocytes containing mature P. c. chabaudi parasites are sequestered from the peripheral circulation. Sequestration is organ specific, occurring primarily in the liver, although intimate contact between infected erythrocytes and endothelial cells is also observed in the spleen and brain. The results are discussed in the context of the use of this model to study (i) the relationship between endothelial cell activation and the level of sequestration and (ii) the primary function of sequestration in malaria infection. PMID:10858230

  10. Efficacy of chloroquine for the treatment of uncomplicated Plasmodium falciparum malaria in Honduras.

    PubMed

    Mejia Torres, Rosa Elena; Banegas, Engels Ilich; Mendoza, Meisy; Diaz, Cesar; Bucheli, Sandra Tamara Mancero; Fontecha, Gustavo A; Alam, Md Tauqeer; Goldman, Ira; Udhayakumar, Venkatachalam; Zambrano, Jose Orlinder Nicolas

    2013-05-01

    Chloroquine (CQ) is officially used for the primary treatment of Plasmodium falciparum malaria in Honduras. In this study, the therapeutic efficacy of CQ for the treatment of uncomplicated P. falciparum malaria in the municipality of Puerto Lempira, Gracias a Dios, Honduras was evaluated using the Pan American Health Organization-World Health Organization protocol with a follow-up of 28 days. Sixty-eight patients from 6 months to 60 years of age microscopically diagnosed with uncomplicated P. falciparum malaria were included in the final analysis. All patients who were treated with CQ (25 mg/kg over 3 days) cleared parasitemia by day 3 and acquired no new P. falciparum infection within 28 days of follow-up. All the parasite samples sequenced for CQ resistance mutations (pfcrt) showed only the CQ-sensitive genotype (CVMNK). This finding shows that CQ remains highly efficacious for the treatment of uncomplicated P. falciparum malaria in Gracias a Dios, Honduras.

  11. Host iron status and iron supplementation mediate susceptibility to erythrocytic stage Plasmodium falciparum.

    PubMed

    Clark, Martha A; Goheen, Morgan M; Fulford, Anthony; Prentice, Andrew M; Elnagheeb, Marwa A; Patel, Jaymin; Fisher, Nancy; Taylor, Steve M; Kasthuri, Raj S; Cerami, Carla

    2014-07-25

    Iron deficiency and malaria have similar global distributions, and frequently co-exist in pregnant women and young children. Where both conditions are prevalent, iron supplementation is complicated by observations that iron deficiency anaemia protects against falciparum malaria, and that iron supplements increase susceptibility to clinically significant malaria, but the mechanisms remain obscure. Here, using an in vitro parasite culture system with erythrocytes from iron-deficient and replete human donors, we demonstrate that Plasmodium falciparum infects iron-deficient erythrocytes less efficiently. In addition, owing to merozoite preference for young erythrocytes, iron supplementation of iron-deficient individuals reverses the protective effects of iron deficiency. Our results provide experimental validation of field observations reporting protective effects of iron deficiency and harmful effects of iron administration on human malaria susceptibility. Because recovery from anaemia requires transient reticulocytosis, our findings imply that in malarious regions iron supplementation should be accompanied by effective measures to prevent falciparum malaria.

  12. Malaria morbidity in Papua Indonesia, an area with multidrug resistant Plasmodium vivax and Plasmodium falciparum

    PubMed Central

    Karyana, Muhammad; Burdarm, Lenny; Yeung, Shunmay; Kenangalem, Enny; Wariker, Noah; Maristela, Rilia; Umana, Ketut Gde; Vemuri, Ram; Okoseray, Maurits J; Penttinen, Pasi M; Ebsworth, Peter; Sugiarto, Paulus; Anstey, Nicholas M; Tjitra, Emiliana; Price, Richard N

    2008-01-01

    Background Multidrug resistance has emerged to both Plasmodium vivax and Plasmodium falciparum and yet the comparative epidemiology of these infections is poorly defined. Methods All laboratory-confirmed episodes of malaria in Timika, Papua, Indonesia, presenting to community primary care clinics and an inpatient facility were reviewed over a two-year period. In addition information was gathered from a house-to-house survey to quantify the prevalence of malaria and treatment-seeking behaviour of people with fever. Results Between January 2004 and December 2005, 99,158 laboratory-confirmed episodes of malaria were reported, of which 58% (57,938) were attributable to P. falciparum and 37% (36,471) to P. vivax. Malaria was most likely to be attributable to pure P. vivax in children under one year of age (55% 2,684/4,889). In the household survey, the prevalence of asexual parasitaemia was 7.5% (290/3,890) for P. falciparum and 6.4% (248/3,890) for P. vivax. The prevalence of P. falciparum infection peaked in young adults aged 15–25 years (9.8% 69/707), compared to P. vivax infection which peaked in children aged 1 to 4 years (9.5% 61/642). Overall 35% (1,813/5,255) of people questioned reported a febrile episode in the preceding month. Of the 60% of people who were estimated to have had malaria, only 39% would have been detected by the surveillance network. The overall incidence of malaria was therefore estimated as 876 per 1,000 per year (Range: 711–906). Conclusion In this region of multidrug-resistant P. vivax and P. falciparum, both species are associated with substantial morbidity, but with significant differences in the age-related risk of infection. PMID:18673572

  13. Molecular Investigation into a Malaria Outbreak in Cusco, Peru: Plasmodium falciparum BV1 Lineage is Linked to a Second Outbreak in Recent Times.

    PubMed

    Okoth, Sheila Akinyi; Chenet, Stella M; Arrospide, Nancy; Gutierrez, Sonia; Cabezas, Cesar; Matta, Jose Antonio; Udhayakumar, Venkatachalam

    2016-01-01

    In November 2013, a Plasmodium falciparum malaria outbreak of 11 cases occurred in Cusco, southern Peru, where falciparum malaria had not been reported since 1946. Although initial microscopic diagnosis reported only Plasmodium vivax infection in each of the specimens, subsequent examination by the national reference laboratory confirmed P. falciparum infection in all samples. Molecular typing of four available isolates revealed identity as the B-variant (BV1) strain that was responsible for a malaria outbreak in Tumbes, northern Peru, between 2010 and 2012. The P. falciparum BV1 strain is multidrug resistant, can escape detection by PfHRP2-based rapid diagnostic tests, and has contributed to two malaria outbreaks in Peru. This investigation highlights the importance of accurate species diagnosis given the potential for P. falciparum to be reintroduced to regions where it may have been absent. Similar molecular epidemiological investigations can track the probable source(s) of outbreak parasite strains for malaria surveillance and control purposes.

  14. Molecular Investigation into a Malaria Outbreak in Cusco, Peru: Plasmodium falciparum BV1 Lineage is Linked to a Second Outbreak in Recent Times.

    PubMed

    Okoth, Sheila Akinyi; Chenet, Stella M; Arrospide, Nancy; Gutierrez, Sonia; Cabezas, Cesar; Matta, Jose Antonio; Udhayakumar, Venkatachalam

    2016-01-01

    In November 2013, a Plasmodium falciparum malaria outbreak of 11 cases occurred in Cusco, southern Peru, where falciparum malaria had not been reported since 1946. Although initial microscopic diagnosis reported only Plasmodium vivax infection in each of the specimens, subsequent examination by the national reference laboratory confirmed P. falciparum infection in all samples. Molecular typing of four available isolates revealed identity as the B-variant (BV1) strain that was responsible for a malaria outbreak in Tumbes, northern Peru, between 2010 and 2012. The P. falciparum BV1 strain is multidrug resistant, can escape detection by PfHRP2-based rapid diagnostic tests, and has contributed to two malaria outbreaks in Peru. This investigation highlights the importance of accurate species diagnosis given the potential for P. falciparum to be reintroduced to regions where it may have been absent. Similar molecular epidemiological investigations can track the probable source(s) of outbreak parasite strains for malaria surveillance and control purposes. PMID:26483121

  15. Analysis of genetic mutations associated with anti-malarial drug resistance in Plasmodium falciparum from the Democratic Republic of East Timor

    PubMed Central

    de Almeida, Afonso; Arez, Ana Paula; Cravo, Pedro VL; do Rosário, Virgílio E

    2009-01-01

    Background In response to chloroquine (CQ) resistance, the policy for the first-line treatment of uncomplicated malaria in the Democratic Republic of East Timor (DRET) was changed in early 2000. The combination of sulphadoxine-pyrimethamine (SP) was then introduced for the treatment of uncomplicated falciparum malaria. Methods Blood samples were collected in two different periods (2003–2004 and 2004–2005) from individuals attending hospitals or clinics in six districts of the DRET and checked for Plasmodium falciparum infection. 112 PCR-positive samples were inspected for genetic polymorphisms in the pfcrt, pfmdr1, pfdhfr and pfdhps genes. Different alleles were interrogated for potential associations that could be indicative of non-random linkage. Results Overall prevalence of mutations associated with resistance to CQ and SP was extremely high. The mutant form of Pfcrt (76T) was found to be fixed even after five years of alleged CQ removal. There was a significant increase in the prevalence of the pfdhps 437G mutation (X2 = 31.1; p = 0.001) from the first to second survey periods. A non-random association was observed between pfdhfr51/pfdhps437 (p = 0.001) and pfdhfr 59/pfdhps 437 (p = 0.013) alleles. Conclusion Persistence of CQ-resistant mutants even after supposed drug withdrawal suggests one or all of the following: local P. falciparum may still be inadvertently exposed to the drug, that mutant parasites are being "imported" into the country, and/or reduced genetic diversity and low parasite transmission help maintain mutant haplotypes. The association between pfdhfr51/pfdhps437 and pfdhfr 59/pfdhps 437 alleles indicates that these are undergoing concomitant positive selection in the DRET. PMID:19358729

  16. Multiplicity of Infection and Disease Severity in Plasmodium vivax

    PubMed Central

    Pacheco, M. Andreína; Lopez-Perez, Mary; Vallejo, Andrés F.; Herrera, Sócrates; Arévalo-Herrera, Myriam; Escalante, Ananias A.

    2016-01-01

    Background Multiplicity of infection (MOI) refers to the average number of distinct parasite genotypes concurrently infecting a patient. Although several studies have reported on MOI and the frequency of multiclonal infections in Plasmodium falciparum, there is limited data on Plasmodium vivax. Here, MOI and the frequency of multiclonal infections were studied in areas from South America where P. vivax and P. falciparum can be compared. Methodology/Principal Findings As part of a passive surveillance study, 1,328 positive malaria patients were recruited between 2011 and 2013 in low transmission areas from Colombia. Of those, there were only 38 P. vivax and 24 P. falciparum clinically complicated cases scattered throughout the time of the study. Samples from uncomplicated cases were matched in time and location with the complicated cases in order to compare the circulating genotypes for these two categories. A total of 92 P. vivax and 57 P. falciparum uncomplicated cases were randomly subsampled. All samples were genotyped by using neutral microsatellites. Plasmodium vivax showed more multiclonal infections (47.7%) than P. falciparum (14.8%). Population genetics and haplotype network analyses did not detect differences in the circulating genotypes between complicated and uncomplicated cases in each parasite. However, a Fisher exact test yielded a significant association between having multiclonal P. vivax infections and complicated malaria. No association was found for P. falciparum infections. Conclusion The association between multiclonal infections and disease severity in P. vivax is consistent with previous observations made in rodent malaria. The contrasting pattern between P. vivax and P. falciparum could be explained, at least in part, by the fact that P. vivax infections have lineages that were more distantly related among them than in the case of the P. falciparum multiclonal infections. Future research should address the possible role that acquired

  17. Clinical and Laboratory Features of Human Plasmodium knowlesi Infection

    PubMed Central

    Daneshvar, Cyrus; Davis, Timothy M. E.; Cox-Singh, Janet; Rafa’ee, Mohammad Zakri; Zakaria, Siti Khatijah; Divis, Paul C. S.; Singh, Balbir

    2010-01-01

    Background Plasmodium knowlesi is increasingly recognized as a cause of human malaria in Southeast Asia but there are no detailed prospective clinical studies of naturally acquired infections. Methods In a systematic study of the presentation and course of patients with acute P. knowlesi infection, clinical and laboratory data were collected from previously untreated, nonpregnant adults admitted to the hospital with polymerase chain reaction–confirmed acute malaria at Kapit Hospital (Sarawak, Malaysia) from July 2006 through February 2008. Results Of 152 patients recruited, 107 (70%) had P. knowlesi infection, 24 (16%) had Plasmodium falciparum infection, and 21 (14%) had Plasmodium vivax. Patients with P. knowlesi infection presented with a nonspecific febrile illness, had a baseline median parasitemia value at hospital admission of 1387 parasites/μL (interquartile range, 6–222,570 parasites/μL), and all were thrombocytopenic at hospital admission or on the following day. Most (93.5%) of the patients with P. knowlesi infection had uncomplicated malaria that responded to chloroquine and primaquine treatment. Based on World Health Organization criteria for falciparum malaria, 7 patients with P. knowlesi infection (6.5%) had severe infections at hospital admission. The most frequent complication was respiratory distress, which was present at hospital admission in 4 patients and developed after admission in an additional 3 patients. P. knowlesi parasitemia at hospital admission was an independent determinant of respiratory distress, as were serum creatinine level, serum bilirubin, and platelet count at admission (P < .002 for each). Two patients with knowlesi malaria died, representing a case fatality rate of 1.8% (95% confidence interval, 0.2%–6.6%). Conclusions Knowlesi malaria causes a wide spectrum of disease. Most cases are uncomplicated and respond promptly to treatment, but approximately 1 in 10 patients develop potentially fatal complications. PMID

  18. Plasmodium falciparum Acyl Carrier Protein Crystal Structures in Disulfide-linked and Reduced States and their Prevalence during Blood Stage Growth

    PubMed Central

    Gallagher, John R.; Prigge, Sean T.

    2009-01-01

    Acyl Carrier Protein (ACP) has a single reactive sulfhydryl necessary for function in covalently binding nascent fatty acids during biosynthesis. In Plasmodium falciparum, the causative agent of the most lethal form of malaria, fatty acid biosynthesis occurs in the apicoplast organelle during the liver stage of the parasite life cycle. During the blood stage, fatty acid biosynthesis is inactive and the redox state of the apicoplast has not been determined. We solved the crystal structure of ACP from P. falciparum in reduced and disulfide-linked forms, and observe the surprising result that the disulfide in the PfACP cross-linked dimer is sequestered from bulk solvent in a tight molecular interface. We assessed solvent accessibility of the disulfide with small molecule reducing agents and found that the disulfide is protected from BME but less so for other common reducing agents. We examined cultured P. falciparum parasites to determine which form of PfACP is prevalent during the blood stages. We readily detected monomeric PfACP in parasite lysate, but do not observe the disulfide-linked form, even under conditions of oxidative stress. To demonstrate that PfACP contains a free sulfhydryl and is not acylated or in the apo state, we treated blood stage parasites with the disulfide forming reagent diamide. We found that the effects of diamide are reversed with reducing agent. Together, these results suggest that the apicoplast is a reducing compartment, as suggested by models of P. falciparum metabolism, and that PfACP is maintained in a reduced state during blood stage growth. PMID:19768685

  19. Species-Specific Inhibition of Cerebral Malaria in Mice Coinfected with Plasmodium spp.

    PubMed Central

    Voza, Tatiana; Vigário, Ana M.; Belnoue, Elodie; Grüner, Anne Charlotte; Deschemin, Jean-Christophe; Kayibanda, Michèle; Delmas, Florian; Janse, Chris J.; Franke-Fayard, Blandine; Waters, Andrew P.; Landau, Irène; Snounou, Georges; Rénia, Laurent

    2005-01-01

    Recent epidemiological observations suggest that clinical evolution of Plasmodium falciparum infections might be influenced by the concurrent presence of another Plasmodium species, and such mixed-species infections are now known to occur frequently in residents of most areas of endemicity. We used mice infected with P. berghei ANKA (PbA), a model for cerebral malaria (CM), to investigate the influence of experimental mixed-species infections on the expression of this pathology. Remarkably, the development of CM was completely inhibited by the simultaneous presence of P. yoelii yoelii but not that of P. vinckei or another line of P. berghei. In the protected coinfected mice, the accumulation of CD8+ T cells in the brain vasculature, a pivotal step in CM pathogenesis, was found to be abolished. Protection from CM was further found to be associated with species-specific suppression of PbA multiplication. These observations establish the concept of mixed Plasmodium species infections as potential modulators of pathology and open novel avenues to investigate mechanisms implicated in the pathogenesis of malaria. PMID:16040990

  20. Admission of Hb S heterozygotes to a general hospital is relatively reduced in malarial areas.

    PubMed Central

    Colombo, B; Felicetti, L

    1985-01-01

    A comparison between the frequency of Hb S heterozygotes in blood donors, outpatients, and inpatients of a general hospital carried out at the Maputo Central Hospital, Mozambique, where Plasmodium falciparum malaria is endemic, showed a statistically significant lower percentage of Hb S heterozygotes in the inpatient group. Evidence is thus provided that the protection given by Hb S to heterozygotes concerns not only malarial infection itself, but probably a wide spectrum of diseases to which persons who have a special resistance to P falciparum infection are less prone. PMID:4045956

  1. Primary structure and subcellular localization of the knob-associated histidine-rich protein of Plasmodium falciparum.

    PubMed Central

    Pologe, L G; Pavlovec, A; Shio, H; Ravetch, J V

    1987-01-01

    Plasmodium falciparum-infected erythrocytes bind to venular endothelial cells by means of electron-dense deformations (knobs) on the parasitized erythrocyte surface. The primary structure of a parasite-derived histidine-rich protein associated with the knob structure was deduced from cDNA sequence analysis. The 634 amino acid sequence is rich in lysine and histidine and contains three distinct, tandemly repeated domains. Indirect immunofluorescence, using affinity-purified monospecific antibodies directed against recombinant protein synthesized in Escherichia coli, localized the knob-associated histidine-rich protein to the membrane of knobby infected erythrocytes. Immunoelectron microscopy established that the protein is clustered on the cytoplasmic side of the erythrocyte membrane and is associated with the electron-dense knobs. A role for this histidine-rich protein in knob structure and cytoadherence is suggested based upon these data. Images PMID:3313387

  2. [Multiple and successive treatment failures in a patient infected by Plasmodium falciparum in Cambodia and treated by dihydroartemisinin-piperaquine].

    PubMed

    Witkowski, B; Khim, N; Kim, S; Domergue, A; Duru, V; Menard, D

    2016-05-01

    Cases of treatment failures following administration of artemisinin-based combination therapies (ACT) remain rare in malaria endemic areas. In Cambodia, however, failures of these treatments are now commonly observed. Usually, these post-treatment recurrences occur only once and a second course of the same treatment is sufficient to cure patients.We describe here an atypical case of a Plasmodium falciparum-infected patient manifesting several malaria recrudescence episodes following dihydroartemisinin-piperaquine (Eurartesim®) treatment. This case report illustrates the current issue of resistance to the latest generation of antimalarial drugs in Southeast Asia and highlights the difficulty in efficaciously fighting malaria in this region if new therapy remains unimplemented. PMID:27100863

  3. Plasmodium falciparum field isolates from areas of repeated emergence of drug resistant malaria show no evidence of hypermutator phenotype.

    PubMed

    Brown, Tyler S; Jacob, Christopher G; Silva, Joana C; Takala-Harrison, Shannon; Djimdé, Abdoulaye; Dondorp, Arjen M; Fukuda, Mark; Noedl, Harald; Nyunt, Myaing Myaing; Kyaw, Myat Phone; Mayxay, Mayfong; Hien, Tran Tinh; Plowe, Christopher V; Cummings, Michael P

    2015-03-01

    Multiple transcontinental waves of drug resistance in Plasmodium falciparum have originated in Southeast Asia before spreading westward, first into the rest of Asia and then to sub-Saharan Africa. In vitro studies have suggested that hypermutator P. falciparum parasites may exist in Southeast Asia and that an increased rate of acquisition of new mutations in these parasites may explain the repeated emergence of drug resistance in Southeast Asia. This study is the first to test the hypermutator hypothesis using field isolates. Using genome-wide SNP data from human P. falciparum infections in Southeast Asia and West Africa and a test for relative rate differences we found no evidence of increased relative substitution rates in P. falciparum isolates from Southeast Asia. Instead, we found significantly increased substitution rates in Mali and Bangladesh populations relative to those in populations from Southeast Asia. Additionally we found no association between increased relative substitution rates and parasite clearance following treatment with artemisinin derivatives.

  4. Plasmodium falciparum field isolates from areas of repeated emergence of drug resistant malaria show no evidence of hypermutator phenotype.

    PubMed

    Brown, Tyler S; Jacob, Christopher G; Silva, Joana C; Takala-Harrison, Shannon; Djimdé, Abdoulaye; Dondorp, Arjen M; Fukuda, Mark; Noedl, Harald; Nyunt, Myaing Myaing; Kyaw, Myat Phone; Mayxay, Mayfong; Hien, Tran Tinh; Plowe, Christopher V; Cummings, Michael P

    2015-03-01

    Multiple transcontinental waves of drug resistance in Plasmodium falciparum have originated in Southeast Asia before spreading westward, first into the rest of Asia and then to sub-Saharan Africa. In vitro studies have suggested that hypermutator P. falciparum parasites may exist in Southeast Asia and that an increased rate of acquisition of new mutations in these parasites may explain the repeated emergence of drug resistance in Southeast Asia. This study is the first to test the hypermutator hypothesis using field isolates. Using genome-wide SNP data from human P. falciparum infections in Southeast Asia and West Africa and a test for relative rate differences we found no evidence of increased relative substitution rates in P. falciparum isolates from Southeast Asia. Instead, we found significantly increased substitution rates in Mali and Bangladesh populations relative to those in populations from Southeast Asia. Additionally we found no association between increased relative substitution rates and parasite clearance following treatment with artemisinin derivatives. PMID:25514047

  5. Plasmodium falciparum field isolates from areas of repeated emergence of drug resistant malaria show no evidence of hypermutator phenotype

    PubMed Central

    Brown, Tyler S.; Jacob, Christopher G.; Silva, Joana C.; Takala-Harrison, Shannon; Djimdé, Abdoulaye; Dondorp, Arjen M.; Fukuda, Mark; Noedl, Harald; Nyunt, Myaing Myaing; Kyaw, Myat Phone; Mayxay, Mayfong; Hien, Tran Tinh; Plowe, Christopher V.; Cummings, Michael P.

    2015-01-01

    Multiple transcontinental waves of drug resistance in Plasmodium falciparum have originated in Southeast Asia before spreading westward, first into the rest of Asia and then to sub-Saharan Africa. In vitro studies have suggested that hypermutator P. falciparum parasites may exist in Southeast Asia and that an increased rate of acquisition of new mutations in these parasites may explain the repeated emergence of drug resistance in Southeast Asia. This study is the first to test the hypermutator hypothesis using field isolates. Using genome-wide SNP data from human P. falciparum infections in Southeast Asia and West Africa and a test for relative rate differences we found no evidence of increased relative substitution rates in P. falciparum isolates from Southeast Asia. Instead, we found significantly increased substitution rates in Mali and Bangladesh populations relative to those in populations from Southeast Asia. Additionally we found no association between increased relative substitution rates and parasite clearance following treatment with artemisinin derivatives. PMID:25514047

  6. A Novel Pyrazolopyridine with in Vivo Activity in Plasmodium berghei- and Plasmodium falciparum-Infected Mouse Models from Structure-Activity Relationship Studies around the Core of Recently Identified Antimalarial Imidazopyridazines.

    PubMed

    Le Manach, Claire; Paquet, Tanya; Brunschwig, Christel; Njoroge, Mathew; Han, Ze; Gonzàlez Cabrera, Diego; Bashyam, Sridevi; Dhinakaran, Rajkumar; Taylor, Dale; Reader, Janette; Botha, Mariette; Churchyard, Alisje; Lauterbach, Sonja; Coetzer, Theresa L; Birkholtz, Lyn-Marie; Meister, Stephan; Winzeler, Elizabeth A; Waterson, David; Witty, Michael J; Wittlin, Sergio; Jiménez-Díaz, María-Belén; Santos Martínez, María; Ferrer, Santiago; Angulo-Barturen, Iñigo; Street, Leslie J; Chibale, Kelly

    2015-11-12

    Toward improving pharmacokinetics, in vivo efficacy, and selectivity over hERG, structure-activity relationship studies around the central core of antimalarial imidazopyridazines were conducted. This study led to the identification of potent pyrazolopyridines, which showed good in vivo efficacy and pharmacokinetics profiles. The lead compounds also proved to be very potent in the parasite liver and gametocyte stages, which makes them of high interest. PMID:26502160

  7. Parasitostatic effect of maslinic acid. I. Growth arrest of Plasmodium falciparum intraerythrocytic stages

    PubMed Central

    2011-01-01

    Background Natural products have played an important role as leads for the development of new drugs against malaria. Recent studies have shown that maslinic acid (MA), a natural triterpene obtained from olive pomace, which displays multiple biological and antimicrobial activities, also exerts inhibitory effects on the development of some Apicomplexan, including Eimeria, Toxoplasma and Neospora. To ascertain if MA displays anti-malarial activity, the main objective of this study was to asses the effect of MA on Plasmodium falciparum-infected erythrocytes in vitro. Methods Synchronized P. falciparum-infected erythrocyte cultures were incubated under different conditions with MA, and compared to chloroquine and atovaquone treated cultures. The effects on parasite growth were determined by monitoring the parasitaemia and the accumulation of the different infective stages visualized in thin blood smears. Results MA inhibits the growth of P. falciparum Dd2 and 3D7 strains in infected erythrocytes in, dose-dependent manner, leading to the accumulation of immature forms at IC50 concentrations, while higher doses produced non-viable parasite cells. MA-treated infected-erythrocyte cultures were compared to those treated with chloroquine or atovaquone, showing significant differences in the pattern of accumulation of parasitic stages. Transient MA treatment at different parasite stages showed that the compound targeted intra-erythrocytic processes from early-ring to schizont stage. These results indicate that MA has a parasitostatic effect, which does not inactivate permanently P. falciparum, as the removal of the compound allowed the infection to continue Conclusions MA displays anti-malarial activity at multiple intraerythrocytic stages of the parasite and, depending on the dose and incubation time, behaves as a plasmodial parasitostatic compound. This novel parasitostatic effect appears to be unrelated to previous mechanisms proposed for current anti-malarial drugs, and

  8. Cortisol, prolactin, cytokines and the susceptibility of pregnant Sudanese women to Plasmodium falciparum malaria.

    PubMed

    Bayoumi, N K; Elhassan, E M; Elbashir, M I; Adam, I

    2009-03-01

    Understanding the hormonal and cytokine interactions that underlie susceptibility to the disease should be helpful in elucidating the pathogenesis of malaria during pregnancy. The current study was conducted in the Wad Medani hospital, in an area of central Sudan that is characterised by unstable malarial transmission. Its aims were to investigate the roles and interactions of cortisol, prolactin, interferon-gamma (IFN-gamma), interleukin-4 (IL-4) and interleukin-10 (IL-10) in pregnant women with Plasmodium falciparum malaria. The 82 pregnant subjects who were enrolled either had uncomplicated, P. falciparum malaria (the 47 cases) or were apparently uninfected and healthy women (the 37 controls) who were similar to the cases in terms of their mean age, weight, gravidity, gestational age and haemoglobin concentration. Compared with the controls, the cases were found to have significantly higher serum concentrations of total cortisol and IL-10 and significantly lower levels of prolactin and IFN-gamma (but similar concentrations of IL-4). The hormone and cytokine concentrations measured in the infected primigravidae were similar to those recorded in the infected multigravidae. Among the cases, there was a significant positive correlation between serum cortisol and IL-10 (r=0.188; P=0.025) and significant negative correlations between prolactin and both IL-4 (r=-0.175; P=0.038) and IL-10 (r=-0.186; P=0.027) but no significant correlation between prolactin and cortisol. During pregnancy, immune responses appear to be influenced by P. falciparum infections, irrespective of parity. Cortisol, prolactin and some cytokines appear to be key mediators in the host response to P. ?falciparum infection, although further research on this subject is clearly needed.

  9. Separation of Plasmodium falciparum Late Stage-infected Erythrocytes by Magnetic Means

    PubMed Central

    Coronado, Lorena Michelle; Tayler, Nicole Michelle; Correa, Ricardo; Giovani, Rita Marissa; Spadafora, Carmenza

    2013-01-01

    Unlike other Plasmodium species, P. falciparum can be cultured in the lab, which facilitates its study 1. While the parasitemia achieved can reach the ≈40% limit, the investigator usually keeps the percentage at around 10%. In many cases it is necessary to isolate the parasite-containing red blood cells (RBCs) from the uninfected ones, to enrich the culture and proceed with a given experiment. When P. falciparum infects the erythrocyte, the parasite degrades and feeds from haemoglobin 2, 3. However, the parasite must deal with a very toxic iron-containing haem moiety 4, 5. The parasite eludes its toxicity by transforming the haem into an inert crystal polymer called haemozoin 6, 7. This iron-containing molecule is stored in its food vacuole and the metal in it has an oxidative state which differs from the one in haem 8. The ferric state of iron in the haemozoin confers on it a paramagnetic property absent in uninfected erythrocytes. As the invading parasite reaches maturity, the content of haemozoin also increases 9, which bestows even more paramagnetism on the latest stages of P. falciparum inside the erythrocyte. Based on this paramagnetic property, the latest stages of P. falciparum infected-red blood cells can be separated by passing the culture through a column containing magnetic beads. These beads become magnetic when the columns containing them are placed on a magnet holder. Infected RBCs, due to their paramagnetism, will then be trapped inside the column, while the flow-through will contain, for the most part, uninfected erythrocytes and those containing early stages of the parasite. Here, we describe the methodology to enrich the population of late stage parasites with magnetic columns, which maintains good parasite viability 10. After performing this procedure, the unattached culture can be returned to an incubator to allow the remaining parasites to continue growing. PMID:23486405

  10. Reduced in vitro doxycycline susceptibility in plasmodium falciparum field isolates from Kenya is associated with PfTetQ KYNNNN sequence polymorphism.

    PubMed

    Achieng, Angela O; Ingasia, Luiser A; Juma, Dennis W; Cheruiyot, Agnes C; Okudo, Charles A; Yeda, Redemptah A; Cheruiyot, Jelagat; Akala, Hoseah M; Johnson, Jacob; Andangalu, Ben; Eyase, Fredrick; Jura, Walter G Z O; Kamau, Edwin

    2014-10-01

    Doxycycline is widely used for malaria prophylaxis by international travelers. However, there is limited information on doxycycline efficacy in Kenya, and genetic polymorphisms associated with reduced efficacy are not well defined. In vitro doxycycline susceptibility profiles for 96 Plasmodium falciparum field isolates from Kenya were determined. Genetic polymorphisms were assessed in P. falciparum metabolite drug transporter (Pfmdt) and P. falciparum GTPase tetQ (PftetQ) genes. Copy number variation of the gene and the number of KYNNNN amino acid motif repeats within the protein encoded by PftetQ were determined. Reduced in vitro susceptibility to doxycycline was defined by 50% inhibitory concentrations (IC50s) of ≥35,000 nM. The odds ratio (OR) of having 2 PfTetQ KYNNNN amino acid repeats in isolates with IC50s of >35,000 nM relative to those with IC50s of <35,000 nM is 15 (95% confidence interval [CI], 3.0 to 74.3; P value of <0.0002). Isolates with 1 copy of the Pfmdt gene had a median IC50 of 6,971 nM, whereas those with a Pfmdt copy number of >1 had a median IC50 of 9,912 nM (P = 0.0245). Isolates with 1 copy of PftetQ had a median IC50 of 6,370 nM, whereas isolates with a PftetQ copy number of >1 had a median IC50 of 3,422 nM (P < 0.0007). Isolates with 2 PfTetQ KYNNNN motif repeats had a median IC50 of 26,165 nM, whereas isolates with 3 PfTetQ KYNNNN repeats had a median IC50 of 3,352 nM (P = 0.0023). PfTetQ sequence polymorphism is associated with a reduced doxycycline susceptibility phenotype in Kenyan isolates and is a potential marker for susceptibility testing. PMID:25070109

  11. Effect of Mature Blood-Stage Plasmodium Parasite Sequestration on Pathogen Biomass in Mathematical and In Vivo Models of Malaria

    PubMed Central

    Khoury, David S.; Cromer, Deborah; Best, Shannon E.; James, Kylie R.; Kim, Peter S.; Engwerda, Christian R.; Haque, Ashraful

    2014-01-01

    Parasite biomass and microvasculature obstruction are strongly associated with disease severity and death in Plasmodium falciparum-infected humans. This is related to sequestration of mature, blood-stage parasites (schizonts) in peripheral tissue. The prevailing view is that schizont sequestration leads to an increase in pathogen biomass, yet direct experimental data to support this are lacking. Here, we first studied parasite population dynamics in inbred wild-type (WT) mice infected with the rodent species of malaria, Plasmodium berghei ANKA. As is commonly reported, these mice became moribund due to large numbers of parasites in multiple tissues. We then studied infection dynamics in a genetically targeted line of mice, which displayed minimal tissue accumulation of parasites. We constructed a mathematical model of parasite biomass dynamics, incorporating schizont-specific host clearance, both with and without schizont sequestration. Combined use of mathematical and in vivo modeling indicated, first, that the slowing of parasite growth in the genetically targeted mice can be attributed to specific clearance of schizonts from the circulation and, second, that persistent parasite growth in WT mice can be explained solely as a result of schizont sequestration. Our work provides evidence that schizont sequestration could be a major biological process driving rapid, early increases in parasite biomass during blood-stage Plasmodium infection. PMID:24144725

  12. Effect of mature blood-stage Plasmodium parasite sequestration on pathogen biomass in mathematical and in vivo models of malaria.

    PubMed

    Khoury, David S; Cromer, Deborah; Best, Shannon E; James, Kylie R; Kim, Peter S; Engwerda, Christian R; Haque, Ashraful; Davenport, Miles P

    2014-01-01

    Parasite biomass and microvasculature obstruction are strongly associated with disease severity and death in Plasmodium falciparum-infected humans. This is related to sequestration of mature, blood-stage parasites (schizonts) in peripheral tissue. The prevailing view is that schizont sequestration leads to an increase in pathogen biomass, yet direct experimental data to support this are lacking. Here, we first studied parasite population dynamics in inbred wild-type (WT) mice infected with the rodent species of malaria, Plasmodium berghei ANKA. As is commonly reported, these mice became moribund due to large numbers of parasites in multiple tissues. We then studied infection dynamics in a genetically targeted line of mice, which displayed minimal tissue accumulation of parasites. We constructed a mathematical model of parasite biomass dynamics, incorporating schizont-specific host clearance, both with and without schizont sequestration. Combined use of mathematical and in vivo modeling indicated, first, that the slowing of parasite growth in the genetically targeted mice can be attributed to specific clearance of schizonts from the circulation and, second, that persistent parasite growth in WT mice can be explained solely as a result of schizont sequestration. Our work provides evidence that schizont sequestration could be a major biological process driving rapid, early increases in parasite biomass during blood-stage Plasmodium infection. PMID:24144725

  13. Plasmodium falciparum evades mosquito immunity by disrupting JNK-mediated apoptosis of invaded midgut cells

    PubMed Central

    Ramphul, Urvashi N.; Garver, Lindsey S.; Molina-Cruz, Alvaro; Canepa, Gaspar E.; Barillas-Mury, Carolina

    2015-01-01

    The malaria parasite, Plasmodium, must survive and develop in the mosquito vector to be successfully transmitted to a new host. The Plasmodium falciparum Pfs47 gene is critical for malaria transmission. Parasites that express Pfs47 (NF54 WT) evade mosquito immunity and survive, whereas Pfs47 knockouts (KO) are efficiently eliminated by the complement-like system. Two alternative approaches were used to investigate the mechanism of action of Pfs47 on immune evasion. First, we examined whether Pfs47 affected signal transduction pathways mediating mosquito immune responses, and show that the Jun-N-terminal kinase (JNK) pathway is a key mediator of Anopheles gambiae antiplasmodial responses to P. falciparum infection and that Pfs47 disrupts JNK signaling. Second, we used microarrays to compare the global transcriptional responses of A. gambiae midguts to infection with WT and KO parasites. The presence of Pfs47 results in broad and profound changes in gene expression in response to infection that are already evident 12 h postfeeding, but become most prominent at 26 h postfeeding, the time when ookinetes invade the mosquito midgut. Silencing of 15 differentially expressed candidate genes identified caspase-S2 as a key effector of Plasmodium elimination in parasites lacking Pfs47. We provide experimental evidence that JNK pathway regulates activation of caspases in Plasmodium-invaded midgut cells, and that caspase activation is required to trigger midgut epithelial nitration. Pfs47 alters the cell death pathway of invaded midgut cells by disrupting JNK signaling and prevents the activation of several caspases, resulting in an ineffective nitration response that makes the parasite undetectable by the mosquito complement-like system. PMID:25552553

  14. Role of the Plasmodium Export Element in Trafficking Parasite Proteins to the Infected Erythrocyte

    PubMed Central

    Boddey, Justin A; Moritz, Robert L; Simpson, Richard J; Cowman, Alan F

    2009-01-01

    The intracellular survival of Plasmodium falciparum within human erythrocytes is dependent on export of parasite proteins that remodel the host cell. Most exported proteins require a conserved motif (RxLxE/Q/D), termed the Plasmodium export element (PEXEL) or vacuolar targeting sequence (VTS), for targeting beyond the parasitophorous vacuole membrane and into the host cell; however, the precise role of this motif in export is poorly defined. We used transgenic P. falciparum expressing chimeric proteins to investigate the function of the PEXEL motif for export. The PEXEL constitutes a bifunctional export motif comprising a protease recognition sequence that is cleaved, in the endoplasmic reticulum, from proteins destined for export, in a PEXEL arginine- and leucine-dependent manner. Following processing, the remaining conserved PEXEL residue is required to direct the mature protein to the host cell. Furthermore, we demonstrate that N acetylation of proteins following N-terminal processing is a PEXEL-independent process that is insufficient for correct export to the host cell. This work defines the role of each residue in the PEXEL for export into the P. falciparum-infected erythrocyte. PMID:19055692

  15. Immunogenicity of the Plasmodium falciparum PfEMP1-VarO Adhesin: Induction of Surface-Reactive and Rosette-Disrupting Antibodies to VarO Infected Erythrocytes.

    PubMed

    Guillotte, Micheline; Juillerat, Alexandre; Igonet, Sébastien; Hessel, Audrey; Petres, Stéphane; Crublet, Elodie; Le Scanf, Cécile; Lewit-Bentley, Anita; Bentley, Graham A; Vigan-Womas, Inès; Mercereau-Puijalon, Odile

    2015-01-01

    Adhesion of Plasmodium falciparum-infected red blood cells (iRBC) to human erythrocytes (i.e. rosetting) is associated with severe malaria. Rosetting results from interactions between a subset of variant PfEMP1 (Plasmodium falciparum erythrocyte membrane protein 1) adhesins and specific erythrocyte receptors. Interfering with such interactions is considered a promising intervention against severe malaria. To evaluate the feasibility of a vaccine strategy targetting rosetting, we have used here the Palo Alto 89F5 VarO rosetting model. PfEMP1-VarO consists of five Duffy-Binding Like domains (DBL1-5) and one Cysteine-rich Interdomain Region (CIDR1). The binding domain has been mapped to DBL1 and the ABO blood group was identified as the erythrocyte receptor. Here, we study the immunogenicity of all six recombinant PfEMP1-VarO domains and the DBL1- CIDR1 Head domain in BALB/c and outbred OF1 mice. Five readouts of antibody responses are explored: ELISA titres on the recombinant antigen, VarO-iRBC immunoblot reactivity, VarO-iRBC surface-reactivity, capacity to disrupt VarO rosettes and the capacity to prevent VarO rosette formation. For three domains, we explore influence of the expression system on antigenicity and immunogenicity. We show that correctly folded PfEMP1 domains elicit high antibody titres and induce a homogeneous response in outbred and BALB/c mice after three injections. High levels of rosette-disrupting and rosette-preventing antibodies are induced by DBL1 and the Head domain. Reduced-alkylated or denatured proteins fail to induce surface-reacting and rosette-disrupting antibodies, indicating that surface epitopes are conformational. We also report limited cross-reactivity between some PfEMP1 VarO domains. These results highlight the high immunogenicity of the individual domains in outbred animals and provide a strong basis for a rational vaccination strategy targeting rosetting. PMID:26222304

  16. Selective killing of the human malaria parasite Plasmodium falciparum by a benzylthiazolium dye.

    PubMed

    Kelly, Jane X; Winter, Rolf W; Braun, Theodore P; Osei-Agyemang, Myralyn; Hinrichs, David J; Riscoe, Michael K

    2007-06-01

    Malaria is an infectious disease caused by protozoan parasites of the genus Plasmodium. The most virulent form of the disease is caused by Plasmodium falciparum which infects hundreds of millions of people and is responsible for the deaths of 1-2 million individuals each year. An essential part of the parasitic process is the remodeling of the red blood cell membrane and its protein constituents to permit a higher flux of nutrients and waste products into or away from the intracellular parasite. Much of this increased permeability is due to a single type of broad specificity channel variously called the new permeation pathway (NPP), the nutrient channel, and the Plasmodial surface anion channel (PSAC). This channel is permeable to a range of low molecular weight solutes both charged and uncharged, with a strong preference for anions. Drugs such as furosemide that are known to block anion-selective channels inhibit PSAC. In this study, we have investigated a dye known as benzothiocarboxypurine, BCP, which had been studied as a possible diagnostic aid given its selective uptake by P. falciparum infected red cells. We found that the dye enters parasitized red cells via the furosemide-inhibitable PSAC, forms a brightly fluorescent complex with parasite nucleic acids, and is selectively toxic to infected cells. Our study describes an antimalarial agent that exploits the altered permeability of Plasmodium-infected red cells as a means to killing the parasite and highlights a chemical reagent that may prove useful in high throughput screening of compounds for inhibitors of the channel.

  17. Protein farnesyltransferase and protein prenylation in Plasmodium falciparum.

    PubMed

    Chakrabarti, Debopam; Da Silva, Thiago; Barger, Jennifer; Paquette, Steve; Patel, Hetal; Patterson, Shelley; Allen, Charles M

    2002-11-01

    Comparison of the malaria parasite and mammalian protein prenyltransferases and their cellular substrates is important for establishing this enzyme as a target for developing antimalarial agents. Nineteen heptapeptides differing only in their carboxyl-terminal amino acid were tested as alternative substrates of partially purified Plasmodium falciparum protein farnesyltransferase. Only NRSCAIM and NRSCAIQ serve as substrates, with NRSCAIM being the best. Peptidomimetics, FTI-276 and GGTI-287, inhibit the transferase with IC(50) values of 1 and 32 nm, respectively. Incubation of P. falciparum-infected erythrocytes with [(3)H]farnesol labels 50- and 22-28-kDa proteins, whereas [(3)H]geranylgeraniol labels only 22-28-kDa proteins. The 50-kDa protein is shown to be farnesylated, whereas the 22-28-kDa proteins are geranylgeranylated, irrespective of the labeling prenol. Protein labeling is inhibited more than 50% by either 5 microm FTI-277 or GGTI-298. The same concentration of inhibitors also inhibits parasite growth from the ring stage by 50%, decreases expression of prenylated proteins as measured with prenyl-specific antibody, and inhibits parasite differentiation beyond the trophozoite stage. Furthermore, differentiation specific prenylation of P. falciparum proteins is demonstrated. Protein labeling is detected predominantly during the trophozoite to schizont and schizont to ring transitions. These results demonstrate unique properties of protein prenylation in P. falciparum: a limited specificity of the farnesyltransferase for peptide substrates compared with mammalian enzymes, the ability to use farnesol to label both farnesyl and geranylgeranyl moieties on proteins, differentiation specific protein prenylation, and the ability of peptidomimetic prenyltransferase inhibitors to block parasite differentiation.

  18. Fucosylated chondroitin sulfate inhibits Plasmodium falciparum cytoadhesion and merozoite invasion.

    PubMed

    Bastos, Marcele F; Albrecht, Letusa; Kozlowski, Eliene O; Lopes, Stefanie C P; Blanco, Yara C; Carlos, Bianca C; Castiñeiras, Catarina; Vicente, Cristina P; Werneck, Claudio C; Wunderlich, Gerhard; Ferreira, Marcelo U; Marinho, Claudio R F; Mourão, Paulo A S; Pavão, Mauro S G; Costa, Fabio T M

    2014-01-01

    Sequestration of Plasmodium falciparum-infected erythrocytes (Pf-iEs) in the microvasculature of vital organs plays a key role in the pathogenesis of life-threatening malaria complications, such as cerebral malaria and malaria in pregnancy. This phenomenon is marked by the cytoadhesion of Pf-iEs to host receptors on the surfaces of endothelial cells, on noninfected erythrocytes, and in the placental trophoblast; therefore, these sites are potential targets for antiadhesion therapies. In this context, glycosaminoglycans (GAGs), including heparin, have shown the ability to inhibit Pf-iE cytoadherence and growth. Nevertheless, the use of heparin was discontinued due to serious side effects, such as bleeding. Other GAG-based therapies were hampered due to the potential risk of contamination with prions and viruses, as some GAGs are isolated from mammals. In this context, we investigated the effects and mechanism of action of fucosylated chondroitin sulfate (FucCS), a unique and highly sulfated GAG isolated from the sea cucumber, with respect to P. falciparum cytoadhesion and development. FucCS was effective in inhibiting the cytoadherence of Pf-iEs to human lung endothelial cells and placenta cryosections under static and flow conditions. Removal of the sulfated fucose branches of the FucCS structure virtually abolished the inhibitory effects of FucCS. Importantly, FucCS rapidly disrupted rosettes at high levels, and it was also able to block parasite development by interfering with merozoite invasion. Collectively, these findings highlight the potential of FucCS as a candidate for adjunct therapy against severe malaria.

  19. Fucosylated Chondroitin Sulfate Inhibits Plasmodium falciparum Cytoadhesion and Merozoite Invasion

    PubMed Central

    Bastos, Marcele F.; Albrecht, Letusa; Kozlowski, Eliene O.; Lopes, Stefanie C. P.; Blanco, Yara C.; Carlos, Bianca C.; Castiñeiras, Catarina; Vicente, Cristina P.; Werneck, Claudio C.; Wunderlich, Gerhard; Ferreira, Marcelo U.; Marinho, Claudio R. F.; Mourão, Paulo A. S.; Pavão, Mauro S. G.

    2014-01-01

    Sequestration of Plasmodium falciparum-infected erythrocytes (Pf-iEs) in the microvasculature of vital organs plays a key role in the pathogenesis of life-threatening malaria complications, such as cerebral malaria and malaria in pregnancy. This phenomenon is marked by the cytoadhesion of Pf-iEs to host receptors on the surfaces of endothelial cells, on noninfected erythrocytes, and in the placental trophoblast; therefore, these sites are potential targets for antiadhesion therapies. In this context, glycosaminoglycans (GAGs), including heparin, have shown the ability to inhibit Pf-iE cytoadherence and growth. Nevertheless, the use of heparin was discontinued due to serious side effects, such as bleeding. Other GAG-based therapies were hampered due to the potential risk of contamination with prions and viruses, as some GAGs are isolated from mammals. In this context, we investigated the effects and mechanism of action of fucosylated chondroitin sulfate (FucCS), a unique and highly sulfated GAG isolated from the sea cucumber, with respect to P. falciparum cytoadhesion and development. FucCS was effective in inhibiting the cytoadherence of Pf-iEs to human lung endothelial cells and placenta cryosections under static and flow conditions. Removal of the sulfated fucose branches of the FucCS structure virtually abolished the inhibitory effects of FucCS. Importantly, FucCS rapidly disrupted rosettes at high levels, and it was also able to block parasite development by interfering with merozoite invasion. Collectively, these findings highlight the potential of FucCS as a candidate for adjunct therapy against severe malaria. PMID:24395239

  20. Host Erythrocyte Environment Influences the Localization of Exported Protein 2, an Essential Component of the Plasmodium Translocon

    PubMed Central

    Meibalan, Elamaran; Comunale, Mary Ann; Lopez, Ana M.; Bergman, Lawrence W.; Mehta, Anand; Vaidya, Akhil B.

    2015-01-01

    Malaria parasites replicating inside red blood cells (RBCs) export a large subset of proteins into the erythrocyte cytoplasm to facilitate parasite growth and survival. PTEX, the parasite-encoded translocon, mediates protein transport across the parasitophorous vacuolar membrane (PVM) in Plasmodium falciparum-infected erythrocytes. Proteins exported into the erythrocyte cytoplasm have been localized to membranous structures, such as Maurer's clefts, small vesicles, and a tubovesicular network. Comparable studies of protein trafficking in Plasmodium vivax-infected reticulocytes are limited. With Plasmodium yoelii-infected reticulocytes, we identified exported protein 2 (Exp2) in a proteomic screen of proteins putatively transported across the PVM. Immunofluorescence studies showed that P. yoelii Exp2 (PyExp2) was primarily localized to the PVM. Unexpectedly, PyExp2 was also associated with distinct, membrane-bound vesicles in the reticulocyte cytoplasm. This is in contrast to P. falciparum in mature RBCs, where P. falciparum Exp2 (PfExp2) is exclusively localized to the PVM. Two P. yoelii-exported proteins, PY04481 (encoded by a pyst-a gene) and PY06203 (PypAg-1), partially colocalized with these PyExp2-positive vesicles. Further analysis revealed that with P. yoelii, Plasmodium berghei, and P. falciparum, cytoplasmic Exp2-positive vesicles were primarily observed in CD71+ reticulocytes versus mature RBCs. In transgenic P. yoelii 17X parasites, the association of hemagglutinin-tagged PyExp2 with the PVM and cytoplasmic vesicles was retained, but the pyexp2 gene was refractory to deletion. These data suggest that the localization of Exp2 in mouse and human RBCs can be influenced by the host cell environment. Exp2 may function at multiple points in the pathway by which parasites traffic proteins into and through the reticulocyte cytoplasm. PMID:25662767

  1. Establishment of a murine model of cerebral malaria in KunMing mice infected with Plasmodium berghei ANKA.

    PubMed

    Ding, Yan; Xu, Wenyue; Zhou, Taoli; Liu, Taiping; Zheng, Hong; Fu, Yong

    2016-10-01

    Malaria remains one of the most devastating diseases. Cerebral malaria (CM) is a severe complication of Plasmodium falciparum infection resulting in high mortality and morbidity worldwide. Analysis of precise mechanisms of CM in humans is difficult for ethical reasons and animal models of CM have been employed to study malaria pathogenesis. Here, we describe a new experimental cerebral malaria (ECM) model with Plasmodium berghei ANKA infection in KunMing (KM) mice. KM mice developed ECM after blood-stage or sporozoites infection, and the development of ECM in KM mice has a dose-dependent relationship with sporozoites inoculums. Histopathological findings revealed important features associated with ECM, including accumulation of mononuclear cells and red blood cells in brain microvascular, and brain parenchymal haemorrhages. Blood-brain barrier (BBB) examination showed that BBB disruption was present in infected KM mice when displaying clinical signs of CM. In vivo bioluminescent imaging experiment indicated that parasitized red blood cells accumulated in most vital organs including heart, lung, spleen, kidney, liver and brain. The levels of inflammatory cytokines interferon-gamma, tumour necrosis factor-alpha, interleukin (IL)-17, IL-12, IL-6 and IL-10 were all remarkably increased in KM mice infected with P. berghei ANKA. This study indicates that P. berghei ANKA infection in KM mice can be used as ECM model to extend further research on genetic, pharmacological and vaccine studies of CM. PMID:27574013

  2. Genomic Analysis Reveals a Common Breakpoint in Amplifications of the Plasmodium vivax Multidrug Resistance 1 Locus in Thailand

    PubMed Central

    Auburn, Sarah; Serre, David; Pearson, Richard D.; Amato, Roberto; Sriprawat, Kanlaya; To, Sheren; Handayuni, Irene; Suwanarusk, Rossarin; Russell, Bruce; Drury, Eleanor; Stalker, Jim; Miotto, Olivo; Kwiatkowski, Dominic P.; Nosten, Francois; Price, Ric N.

    2016-01-01

    In regions of coendemicity for Plasmodium falciparum and Plasmodium vivax where mefloquine is used to treat P. falciparum infection, drug pressure mediated by increased copy numbers of the multidrug resistance 1 gene (pvmdr1) may select for mefloquine-resistant P. vivax. Surveillance is not undertaken routinely owing in part to methodological challenges in detection of gene amplification. Using genomic data on 88 P. vivax samples from western Thailand, we identified pvmdr1 amplification in 17 isolates, all exhibiting tandem copies of a 37.6–kilobase pair region with identical breakpoints. A novel breakpoint-specific polymerase chain reaction assay was designed to detect the amplification. The assay demonstrated high sensitivity, identifying amplifications in 13 additional, polyclonal infections. Application to 132 further samples identified the common breakpoint in all years tested (2003–2015), with a decline in prevalence after 2012 corresponding to local discontinuation of mefloquine regimens. Assessment of the structure of pvmdr1 amplification in other geographic regions will yield information about the population-specificity of the breakpoints and underlying amplification mechanisms. PMID:27456706

  3. Genomic Analysis Reveals a Common Breakpoint in Amplifications of the Plasmodium vivax Multidrug Resistance 1 Locus in Thailand.

    PubMed

    Auburn, Sarah; Serre, David; Pearson, Richard D; Amato, Roberto; Sriprawat, Kanlaya; To, Sheren; Handayuni, Irene; Suwanarusk, Rossarin; Russell, Bruce; Drury, Eleanor; Stalker, Jim; Miotto, Olivo; Kwiatkowski, Dominic P; Nosten, Francois; Price, Ric N

    2016-10-15

    In regions of coendemicity for Plasmodium falciparum and Plasmodium vivax where mefloquine is used to treat P. falciparum infection, drug pressure mediated by increased copy numbers of the multidrug resistance 1 gene (pvmdr1) may select for mefloquine-resistant P. vivax Surveillance is not undertaken routinely owing in part to methodological challenges in detection of gene amplification. Using genomic data on 88 P. vivax samples from western Thailand, we identified pvmdr1 amplification in 17 isolates, all exhibiting tandem copies of a 37.6-kilobase pair region with identical breakpoints. A novel breakpoint-specific polymerase chain reaction assay was designed to detect the amplification. The assay demonstrated high sensitivity, identifying amplifications in 13 additional, polyclonal infections. Application to 132 further samples identified the common breakpoint in all years tested (2003-2015), with a decline in prevalence after 2012 corresponding to local discontinuation of mefloquine regimens. Assessment of the structure of pvmdr1 amplification in other geographic regions will yield information about the population-specificity of the breakpoints and underlying amplification mechanisms. PMID:27456706

  4. Genomic Analysis Reveals a Common Breakpoint in Amplifications of the Plasmodium vivax Multidrug Resistance 1 Locus in Thailand.

    PubMed

    Auburn, Sarah; Serre, David; Pearson, Richard D; Amato, Roberto; Sriprawat, Kanlaya; To, Sheren; Handayuni, Irene; Suwanarusk, Rossarin; Russell, Bruce; Drury, Eleanor; Stalker, Jim; Miotto, Olivo; Kwiatkowski, Dominic P; Nosten, Francois; Price, Ric N

    2016-10-15

    In regions of coendemicity for Plasmodium falciparum and Plasmodium vivax where mefloquine is used to treat P. falciparum infection, drug pressure mediated by increased copy numbers of the multidrug resistance 1 gene (pvmdr1) may select for mefloquine-resistant P. vivax Surveillance is not undertaken routinely owing in part to methodological challenges in detection of gene amplification. Using genomic data on 88 P. vivax samples from western Thailand, we identified pvmdr1 amplification in 17 isolates, all exhibiting tandem copies of a 37.6-kilobase pair region with identical breakpoints. A novel breakpoint-specific polymerase chain reaction assay was designed to detect the amplification. The assay demonstrated high sensitivity, identifying amplifications in 13 additional, polyclonal infections. Application to 132 further samples identified the common breakpoint in all years tested (2003-2015), with a decline in prevalence after 2012 corresponding to local discontinuation of mefloquine regimens. Assessment of the structure of pvmdr1 amplification in other geographic regions will yield information about the population-specificity of the breakpoints and underlying amplification mechanisms.

  5. Plasmodium knowlesi Skeleton-Binding Protein 1 Localizes to the ‘Sinton and Mulligan’ Stipplings in the Cytoplasm of Monkey and Human Erythrocytes

    PubMed Central

    Lucky, Amuza Byaruhanga; Sakaguchi, Miako; Katakai, Yuko; Kawai, Satoru; Yahata, Kazuhide; Templeton, Thomas J.

    2016-01-01

    The malaria parasite, Plasmodium, exports protein products to the infected erythrocyte to introduce modifications necessary for the establishment of nutrient acquisition and surface display of host interaction ligands. Erythrocyte remodeling impacts parasite virulence and disease pathology and is well documented for the human malaria parasite Plasmodium falciparum, but has been less described for other Plasmodium species. For P. falciparum, the exported protein skeleton-binding protein 1 (PfSBP1) is involved in the trafficking of erythrocyte surface ligands and localized to membranous structures within the infected erythrocyte, termed Maurer's clefts. In this study, we analyzed SBP1 orthologs across the Plasmodium genus by BLAST analysis and conserved gene synteny, which were also recently described by de Niz et al. (2016). To evaluate the localization of an SBP1 ortholog, we utilized the zoonotic malaria parasite, Plasmodium knowlesi. Immunofluorescence assay of transgenic P. knowlesi parasites expressing epitope-tagged recombinant PkSBP1 revealed a punctate staining pattern reminiscent of Maurer's clefts, following infection of either monkey or human erythrocytes. The recombinant PkSBP1-positive puncta co-localized with Giemsa-stained structures, known as ‘Sinton and Mulligan’ stipplings. Immunoelectron microscopy also showed that recombinant PkSBP1 localizes within or on the membranous structures akin to the Maurer's clefts. The recombinant PkSBP1 expressed in P. falciparum-infected erythrocytes co-localized with PfSBP1 at the Maurer's clefts, indicating an analogous trafficking pattern. A member of the P. knowlesi 2TM protein family was also expressed and localized to membranous structures in infected monkey erythrocytes. These results suggest that the trafficking machinery and induced erythrocyte cellular structures of P. knowlesi are similar following infection of both monkey and human erythrocytes, and are conserved with P. falciparum. PMID:27732628

  6. Neutralizing Antibodies against Plasmodium falciparum Associated with Successful Cure after Drug Therapy

    PubMed Central

    Goh, Yun Shan; Peng, Kaitian; Chia, Wan Ni; Siau, Anthony; Chotivanich, Kesinee; Gruner, Anne-Charlotte; Preiser, Peter; Mayxay, Mayfong; Pukrittayakamee, Sasithon; Sriprawat, Kanlaya; Nosten, Francois; White, Nicholas J.

    2016-01-01

    An effective antibody response can assist drug treatment to contribute to better parasite clearance in malaria patients. To examine this, sera were obtained from two groups of adult patients with acute falciparum malaria, prior to drug treatment: patients who (1) have subsequent recrudescent infection, or (2) were cured by Day 28 following treatment. Using a Plasmodium falciparum antigen library, we examined the antibody specificities in these sera. While the antibody repertoire of both sera groups was extremely broad and varied, there was a differential antibody profile between the two groups of sera. The proportion of cured patients with antibodies against EXP1, MSP3, GLURP, RAMA, SEA and EBA181 was higher than the proportion of patients with recrudescent infection. The presence of these antibodies was associated with higher odds of treatment cure. Sera containing all six antibodies impaired the invasion of P. falciparum clinical isolates into erythrocytes. These results suggest that antibodies specific against EXP1, MSP3, GLURP, RAMA, SEA and EBA181 in P. falciparum infections could assist anti-malarial drug treatment and contribute to the resolution of the malarial infection. PMID:27427762

  7. Metabolic Dysregulation Induced in Plasmodium falciparum by Dihydroartemisinin and Other Front-Line Antimalarial Drugs.

    PubMed

    Cobbold, Simon A; Chua, Hwa H; Nijagal, Brunda; Creek, Darren J; Ralph, Stuart A; McConville, Malcolm J

    2016-01-15

    Detailed information on the mode of action of antimalarial drugs can be used to improve existing drugs, identify new drug targets, and understand the basis of drug resistance. In this study we describe the use of a time-resolved, mass spectrometry (MS)-based metabolite profiling approach to map the metabolic perturbations induced by a panel of clinical antimalarial drugs and inhibitors on Plasmodium falciparum asexual blood stages. Drug-induced changes in metabolite levels in P. falciparum-infected erythrocytes were monitored over time using gas chromatography-MS and liquid chromatography-MS and changes in specific metabolic fluxes confirmed by nonstationary [(13)C]-glucose labeling. Dihydroartemisinin (DHA) was found to disrupt hemoglobin catabolism within 1 hour of exposure, resulting in a transient decrease in hemoglobin-derived peptides. Unexpectedly, it also disrupted pyrimidine biosynthesis, resulting in increased [(13)C]-glucose flux toward malate production, potentially explaining the susceptibility of P. falciparum to DHA during early blood-stage development. Unique metabolic signatures were also found for atovaquone, chloroquine, proguanil, cycloguanil and methylene blue. We also show that this approach can be used to identify the mode of action of novel antimalarials, such as the compound Torin 2, which inhibits hemoglobin catabolism. PMID:26150544

  8. Protective value of elevated levels of gamma interferon in serum against exoerythrocytic stages of Plasmodium falciparum.

    PubMed

    Deloron, P; Chougnet, C; Lepers, J P; Tallet, S; Coulanges, P

    1991-09-01

    In vitro experiments suggested that gamma interferon, CD8+ T cells, and anticircumsporozoite antibodies inhibited the exoerythrocytic stages of malaria parasites. To assess the role played in vivo by these factors, we conducted a prospective study in Madagascar. Forty individuals with a negative blood smear were followed for 8 weeks to detect the appearance of parasites in blood. Nineteen subjects remained negative for malaria, whereas 21 individuals became positive during follow-up. Among these, seven presented with blood parasites within the first 2 weeks and were excluded, as they probably were infected by sporozoites at enrollment. When measured at enrollment, antibodies to the synthetic peptide (NANP)5, lymphocyte proliferation with (NANP)5, and various lymphocytes subsets were similar among individuals that later presented with a Plasmodium falciparum blood infection or were not infected. Conversely, the level of gamma interferon in serum was higher in individuals that did not present with a P. falciparum infection during follow-up. These data suggest that gamma interferon may inhibit the malaria exoerythrocytic stages of development under in vivo conditions, as it does in vitro.

  9. Protective value of elevated levels of gamma interferon in serum against exoerythrocytic stages of Plasmodium falciparum.

    PubMed Central

    Deloron, P; Chougnet, C; Lepers, J P; Tallet, S; Coulanges, P

    1991-01-01

    In vitro experiments suggested that gamma interferon, CD8+ T cells, and anticircumsporozoite antibodies inhibited the exoerythrocytic stages of malaria parasites. To assess the role played in vivo by these factors, we conducted a prospective study in Madagascar. Forty individuals with a negative blood smear were followed for 8 weeks to detect the appearance of parasites in blood. Nineteen subjects remained negative for malaria, whereas 21 individuals became positive during follow-up. Among these, seven presented with blood parasites within the first 2 weeks and were excluded, as they probably were infected by sporozoites at enrollment. When measured at enrollment, antibodies to the synthetic peptide (NANP)5, lymphocyte proliferation with (NANP)5, and various lymphocytes subsets were similar among individuals that later presented with a Plasmodium falciparum blood infection or were not infected. Conversely, the level of gamma interferon in serum was higher in individuals that did not present with a P. falciparum infection during follow-up. These data suggest that gamma interferon may inhibit the malaria exoerythrocytic stages of development under in vivo conditions, as it does in vitro. PMID:1774292

  10. Fatal Plasmodium falciparum Malaria Causes Specific Patterns of Splenic Architectural Disorganization

    PubMed Central

    Urban, Britta C.; Hien, Tran T.; Day, Nicholas P.; Phu, Nguyen H.; Roberts, Rachel; Pongponratn, Emsri; Jones, Margret; Mai, Nguyen T. H.; Bethell, Delia; Turner, Gareth D. H.; Ferguson, David; White, Nicholas J.; Roberts, David J.

    2005-01-01

    The spleen is critical for host defense against pathogens, including Plasmodium falciparum. It has a dual role, not only removing aged or antigenically altered erythrocytes from the blood but also as the major lymphoid organ for blood-borne or systemic infections. The human malaria parasite P. falciparum replicates within erythrocytes during asexual blood stages and causes repeated infections that can be associated with severe disease. In spite of the crucial role of the spleen in the innate and acquired immune response to malaria, there is little information on the pathology of the spleen in human malaria. We performed a histological and quantitative immunohistochemical study of spleen sections from Vietnamese adults dying from severe falciparum malaria and compared the findings with the findings for spleen sections from control patients and patients dying from systemic bacterial sepsis. Here we report that the white pulp in the spleens of patients dying from malaria showed a marked architectural disorganization. We observed a marked dissolution of the marginal zones with relative loss of B cells. Furthermore, we found strong HLA-DR expression on sinusoidal lining cells but downregulation on cordal macrophages. P. falciparum infection results in alterations in splenic leukocytes, many of which are not seen in sepsis. PMID:15784539

  11. Neutralizing Antibodies against Plasmodium falciparum Associated with Successful Cure after Drug Therapy.

    PubMed

    Goh, Yun Shan; Peng, Kaitian; Chia, Wan Ni; Siau, Anthony; Chotivanich, Kesinee; Gruner, Anne-Charlotte; Preiser, Peter; Mayxay, Mayfong; Pukrittayakamee, Sasithon; Sriprawat, Kanlaya; Nosten, Francois; White, Nicholas J; Renia, Laurent

    2016-01-01

    An effective antibody response can assist drug treatment to contribute to better parasite clearance in malaria patients. To examine this, sera were obtained from two groups of adult patients with acute falciparum malaria, prior to drug treatment: patients who (1) have subsequent recrudescent infection, or (2) were cured by Day 28 following treatment. Using a Plasmodium falciparum antigen library, we examined the antibody specificities in these sera. While the antibody repertoire of both sera groups was extremely broad and varied, there was a differential antibody profile between the two groups of sera. The proportion of cured patients with antibodies against EXP1, MSP3, GLURP, RAMA, SEA and EBA181 was higher than the proportion of patients with recrudescent infection. The presence of these antibodies was associated with higher odds of treatment cure. Sera containing all six antibodies impaired the invasion of P. falciparum clinical isolates into erythrocytes. These results suggest that antibodies specific against EXP1, MSP3, GLURP, RAMA, SEA and EBA181 in P. falciparum infections could assist anti-malarial drug treatment and contribute to the resolution of the malarial infection. PMID:27427762

  12. Independent Emergence of Artemisinin Resistance Mutations Among Plasmodium falciparum in Southeast Asia

    PubMed Central

    Takala-Harrison, Shannon; Jacob, Christopher G.; Arze, Cesar; Cummings, Michael P.; Silva, Joana C.; Dondorp, Arjen M.; Fukuda, Mark M.; Hien, Tran Tinh; Mayxay, Mayfong; Noedl, Harald; Nosten, Francois; Kyaw, Myat P.; Nhien, Nguyen Thanh Thuy; Imwong, Mallika; Bethell, Delia; Se, Youry; Lon, Chanthap; Tyner, Stuart D.; Saunders, David L.; Ariey, Frederic; Mercereau-Puijalon, Odile; Menard, Didier; Newton, Paul N.; Khanthavong, Maniphone; Hongvanthong, Bouasy; Starzengruber, Peter; Fuehrer, Hans-Peter; Swoboda, Paul; Khan, Wasif A.; Phyo, Aung Pyae; Nyunt, Myaing M.; Nyunt, Myat H.; Brown, Tyler S.; Adams, Matthew; Pepin, Christopher S.; Bailey, Jason; Tan, John C.; Ferdig, Michael T.; Clark, Taane G.; Miotto, Olivo; MacInnis, Bronwyn; Kwiatkowski, Dominic P.; White, Nicholas J.; Ringwald, Pascal; Plowe, Christopher V.

    2015-01-01

    Background. The emergence of artemisinin-resistant Plasmodium falciparum in Southeast Asia threatens malaria treatment efficacy. Mutations in a kelch protein encoded on P. falciparum chromosome 13 (K13) have been associated with resistance in vitro and in field samples from Cambodia. Methods. P. falciparum infections from artesunate efficacy trials in Bangladesh, Cambodia, Laos, Myanmar, and Vietnam were genotyped at 33 716 genome-wide single-nucleotide polymorphisms (SNPs). Linear mixed models were used to test associations between parasite genotypes and parasite clearance half-lives following artesunate treatment. K13 mutations were tested for association with artemisinin resistance, and extended haplotypes on chromosome 13 were examined to determine whether mutations arose focally and spread or whether they emerged independently. Results. The presence of nonreference K13 alleles was associated with prolonged parasite clearance half-life (P = 1.97 × 10−12). Parasites with a mutation in any of the K13 kelch domains displayed longer parasite clearance half-lives than parasites with wild-type alleles. Haplotype analysis revealed both population-specific emergence of mutations and independent emergence of the same mutation in different geographic areas. Conclusions. K13 appears to be a major determinant of artemisinin resistance throughout Southeast Asia. While we found some evidence of spreading resistance, there was no evidence of resistance moving westward from Cambodia into Myanmar. PMID:25180241

  13. Evaluation of FRET real-time PCR assay for rapid detection and differentiation of Plasmodium species in returning travellers and migrants

    PubMed Central

    Safeukui, Innocent; Millet, Pascal; Boucher, Sébastien; Melinard, Laurence; Fregeville, Frédéric; Receveur, Marie-Catherine; Pistone, Thierry; Fialon, Pierre; Vincendeau, Philippe; Fleury, Hervé; Malvy, Denis

    2008-01-01

    Background A simple real-time PCR assay using one set of primer and probe for rapid, sensitive and quantitative detection of Plasmodium species, with simultaneous differentiation of Plasmodium falciparum from the three other Plasmodium species (Plasmodium vivax, Plasmodium ovale and Plasmodium malariae) in febrile returning travellers and migrants was developed and evaluated. Methods Consensus primers were used to amplify a species-specific region of the multicopy 18S rRNA gene, and fluorescence resonance energy transfer hybridization probes were used for detection in a LightCycler platform (Roche). The anchor probe sequence was designed to be perfect matches to the 18S rRNA gene of the fourth Plasmodium species, while the acceptor probe sequence was designed for P. falciparum over a region containing one mismatched, which allowed differentiation of the three other Plasmodium species. The performance characteristics of the real-time PCR assay were compared with those of conventional PCR and microscopy-based diagnosis from 119 individuals with a suspected clinical diagnostic of imported malaria. Results Blood samples with parasite densities less than 0.01% were all detected, and analytical sensitivity was 0.5 parasite per PCR reaction. The melt curve means Tms (standard deviation) in clinical isolates were 60.5°C (0.6°C) for P. falciparum infection and 64.6°C (1.8°C) for non-P. falciparum species. These Tms values of the P. falciparum or non-P. falciparum species did not vary with the geographic origin of the parasite. The real-time PCR results correlated with conventional PCR using both genus-specific (Kappa coefficient: 0.95, 95% confidence interval: 0.9 – 1) or P. falciparum-specific (0.91, 0.8 – 1) primers, or with the microscopy results (0.70, 0.6 – 0.8). The real-time assay was 100% sensitive and specific for differentiation of P. falciparum to non-P. falciparum species, compared with conventional PCR or microscopy. The real-time PCR assay can also

  14. Relationship between Antibody Levels, IgG Binding to Plasmodium falciparum-Infected Erythrocytes, and Disease Outcome in Hospitalized Urban Malaria Patients from Dakar, Sénégal

    PubMed Central

    Mbengue, Babacar; Fall, Mouhamadou Mansour; Sylla Niang, Maguette; Niang, Birahim; Varela, Marie Louise; Diatta, Antoine Marie; Mbow, Moustapha; Ndiaye, Kantome; Ndiaye Diallo, Rokhaya; Dieye, Alioune; Perraut, Ronald

    2016-01-01

    Background. Management of clinical malaria requires the development of reliable diagnostic methods and efficient biomarkers for follow-up of patients. Protection is partly based on IgG responses to parasite antigens exposed at the surface of infected erythrocytes (iRBCs). These IgG responses appeared low during clinical infection, particularly in severe disease. Methods. We analyzed the IgG binding capacity to the surface of live erythrocytes infected by knob positive FCR3 strain. Sera from 69 cerebral malaria (CM) and 72 mild malaria (MM) cases were analyzed by ELISA for IgG responses to five antigens from iRBC and by flow cytometry for IgG binding as expressed in labeling index ratio (LIR). The relationship between IgG levels, LIR, parasitemia, age, and the clinical outcomes was evaluated. Results. We found a significant decrease of LIR in adult CM fatal cases compared to surviving patients (p = 0.019). In MM, LIRs were correlated to IgG anti-iRBC and anti-PfEMP3/5 levels. In CM, no correlation was found between LIR, IgG levels, and parasitemia. Conclusion. The IgG binding assay was able to discriminate outcome of cerebral malaria cases and it deserves further development as a potential functional-associated assay for symptomatic malaria analysis. PMID:27563669

  15. Relationship between Antibody Levels, IgG Binding to Plasmodium falciparum-Infected Erythrocytes, and Disease Outcome in Hospitalized Urban Malaria Patients from Dakar, Sénégal.

    PubMed

    Mbengue, Babacar; Fall, Mouhamadou Mansour; Sylla Niang, Maguette; Niang, Birahim; Varela, Marie Louise; Diatta, Antoine Marie; Mbow, Moustapha; Ndiaye, Kantome; Ndiaye Diallo, Rokhaya; Dieye, Alioune; Perraut, Ronald

    2016-01-01

    Background. Management of clinical malaria requires the development of reliable diagnostic methods and efficient biomarkers for follow-up of patients. Protection is partly based on IgG responses to parasite antigens exposed at the surface of infected erythrocytes (iRBCs). These IgG responses appeared low during clinical infection, particularly in severe disease. Methods. We analyzed the IgG binding capacity to the surface of live erythrocytes infected by knob positive FCR3 strain. Sera from 69 cerebral malaria (CM) and 72 mild malaria (MM) cases were analyzed by ELISA for IgG responses to five antigens from iRBC and by flow cytometry for IgG binding as expressed in labeling index ratio (LIR). The relationship between IgG levels, LIR, parasitemia, age, and the clinical outcomes was evaluated. Results. We found a significant decrease of LIR in adult CM fatal cases compared to surviving patients (p = 0.019). In MM, LIRs were correlated to IgG anti-iRBC and anti-PfEMP3/5 levels. In CM, no correlation was found between LIR, IgG levels, and parasitemia. Conclusion. The IgG binding assay was able to discriminate outcome of cerebral malaria cases and it deserves further development as a potential functional-associated assay for symptomatic malaria analysis. PMID:27563669

  16. Submicroscopic and Asymptomatic Plasmodium Parasitaemia Associated with Significant Risk of Anaemia in Papua, Indonesia

    PubMed Central

    Handayuni, Irene; Trianty, Leily; Utami, Retno A. S.; Tirta, Yusrifar Kharisma; Kenangalem, Enny; Lampah, Daniel; Kusuma, Andreas; Wirjanata, Grennady; Kho, Steven; Simpson, Julie A.; Auburn, Sarah; Douglas, Nicholas M.; Noviyanti, Rintis; Anstey, Nicholas M.; Poespoprodjo, Jeanne R.; Marfurt, Jutta

    2016-01-01

    Submicroscopic Plasmodium infections are an important parasite reservoir, but their clinical relevance is poorly defined. A cross-sectional household survey was conducted in southern Papua, Indonesia, using cluster random sampling. Data were recorded using a standardized questionnaire. Blood samples were collected for haemoglobin measurement. Plasmodium parasitaemia was determined by blood film microscopy and PCR. Between April and July 2013, 800 households and 2,830 individuals were surveyed. Peripheral parasitaemia was detected in 37.7% (968/2,567) of individuals, 36.8% (357) of whom were identified by blood film examination. Overall the prevalence of P. falciparum parasitaemia was 15.4% (396/2567) and that of P. vivax 18.3% (471/2567). In parasitaemic individuals, submicroscopic infection was significantly more likely in adults (adjusted odds ratio (AOR): 3.82 [95%CI: 2.49–5.86], p<0.001) compared to children, females (AOR = 1.41 [1.07–1.86], p = 0.013), individuals not sleeping under a bednet (AOR = 1.4 [1.0–1.8], p = 0.035), and being afebrile (AOR = 3.2 [1.49–6.93], p = 0.003). The risk of anaemia (according to WHO guidelines) was 32.8% and significantly increased in those with asymptomatic parasitaemia (AOR 2.9 [95% 2.1–4.0], p = 0.007), and submicroscopic P. falciparum infections (AOR 2.5 [95% 1.7–3.6], p = 0.002). Asymptomatic and submicroscopic infections in this area co-endemic for P. falciparum and P. vivax constitute two thirds of detectable parasitaemia and are associated with a high risk of anaemia. Novel public health strategies are needed to detect and eliminate these parasite reservoirs, for the benefit both of the patient and the community. PMID:27788243

  17. Linking Murine and Human Plasmodium falciparum Challenge Models in a Translational Path for Antimalarial Drug Development

    PubMed Central

    McCarthy, James S.; Marquart, Louise; Sekuloski, Silvana; Trenholme, Katharine; Elliott, Suzanne; Griffin, Paul; Rockett, Rebecca; O'Rourke, Peter; Sloots, Theo; Angulo-Barturen, Iñigo; Ferrer, Santiago; Jiménez-Díaz, María Belén; Martínez, María-Santos; Duparc, Stephan; Leroy, Didier; Wells, Timothy N. C.; Baker, Mark

    2016-01-01

    Effective progression of candidate antimalarials is dependent on optimal dosing in clinical studies, which is determined by a sound understanding of pharmacokinetics and pharmacodynamics (PK/PD). Recently, two important translational models for antimalarials have been developed: the NOD/SCID/IL2Rγ−/− (NSG) model, whereby mice are engrafted with noninfected and Plasmodium falciparum-infected human erythrocytes, and the induced blood-stage malaria (IBSM) model in human volunteers. The antimalarial mefloquine was used to directly measure the PK/PD in both models, which were compared to previously published trial data for malaria patients. The clinical part was a single-center, controlled study using a blood-stage Plasmodium falciparum challenge inoculum in volunteers to characterize the effectiveness of mefloquine against early malaria. The study was conducted in three cohorts (n = 8 each) using different doses of mefloquine. The characteristic delay in onset of action of about 24 h was seen in both NSG and IBSM systems. In vivo 50% inhibitory concentrations (IC50s) were estimated at 2.0 μg/ml and 1.8 μg/ml in the NSG and IBSM models, respectively, aligning with 1.8 μg/ml reported previously for patients. In the IBSM model, the parasite reduction ratios were 157 and 195 for the 10- and 15-mg/kg doses, within the range of previously reported clinical data for patients but significantly lower than observed in the mouse model. Linking mouse and human challenge models to clinical trial data can accelerate the accrual of critical data on antimalarial drug activity. Such data can guide large clinical trials required for development of urgently needed novel antimalarial combinations. (This trial was registered at the Australian New Zealand Clinical Trials Registry [http://anzctr.org.au] under registration number ACTRN12612000323820.) PMID:27044554

  18. VEGF and LPS synergistically silence inflammatory response to Plasmodium berghei infection and protect against cerebral malaria.

    PubMed

    Canavese, Miriam; Dottorini, Tania; Crisanti, Andrea

    2015-09-01

    Malaria infection induces, alongside endothelial damage and obstruction hypoxia, a potent inflammatory response similar to that observed in other systemic diseases caused by bacteria and viruses. Accordingly, it is increasingly recognised that cerebral malaria (CM), the most severe and life threatening complication of Plasmodium falciparum infection, bears a number of similarities with sepsis, an often fatal condition associated with a misregulated inflammatory response triggered by systemic microbial infections. Using a Plasmodium berghei ANKA mouse model, histology, immunohistochemistry and gene expression analysis, we showed that lipopolysaccharide S (LPS), at doses that normally induce inflammation tolerance, protects P. berghei infected mice against experimental CM (ECM). Vascular endothelial growth factor (VEGF) preserved blood vessel integrity, and the combination with LPS resulted in a strong synergistic effect. Treated mice did not develop ECM, showed a prolonged survival and failed to develop a significant inflammatory response and splenomegaly in spite of normal parasite loads. The protective role of VEGF was further confirmed by the observation that the treatment of P. berghei infected C57BL/6 and Balb/c mice with the VEGF receptor inhibitor axitinib exacerbates cerebral pathology and aggravates the course of infection. Infected mice treated with VEGF and LPS showed an induction of the anti-inflammatory genes Nrf2 and HO-1 and a suppression to basal levels of the genes IFN-γ and TNF-α. These results provide the rationale for developing new therapeutic approaches against CM and shed new light on how the inflammatory process can be modulated in the presence of systemic infectious diseases.

  19. Selective Killing of the Human Malaria Parasite Plasmodium falciparum by a Benzylthiazolium dye

    PubMed Central

    Kelly, Jane X.; Winter, Rolf W.; Braun, Theodore P.; Osei-Agyemang, Myralyn; Hinrichs, David J.; Riscoe, Michael K.

    2007-01-01

    Malaria is an infectious disease caused by protozoan parasites of the genus Plasmodium. The most virulent form of the disease is caused by P. falciparum which infects hundreds of millions of people and is responsible for the deaths of 1 to 2 million individuals each year. An essential part of the parasitic process is the remodeling of the red blood cell membrane and its protein constituents to permit a higher flux of nutrients and waste products into or away from the intracellular parasite. Much of this increased permeability is due to a single type of broad specificity channel variously called the new permeation pathway (NPP), the nutrient channel, and the Plasmodial surface anion channel (PSAC). This channel is permeable to a range of low molecular weight solutes both charged and uncharged, with a strong preference for anions. Drugs such as furosemide that are known to block anion-selective channels inhibit PSAC. In this study we have investigated a dye known as benzothiocarboxypurine, BCP, which had been studied as a possible diagnostic aid given its selective uptake by P. falciparum infected red cells. We found that the dye enters parasitized red cells via the furosemide-inhibitable PSAC, forms a brightly fluorescent complex with parasite nucleic acids, and is selectively toxic to infected cells. Our study describes an antimalarial agent that exploits the altered permeability of Plasmodium-infected red cells as a means to killing the parasite and highlights a chemical reagent that may prove useful in high throughput screening of compounds for inhibitors of the channel. PMID:17266952

  20. Linking Murine and Human Plasmodium falciparum Challenge Models in a Translational Path for Antimalarial Drug Development.

    PubMed

    McCarthy, James S; Marquart, Louise; Sekuloski, Silvana; Trenholme, Katharine; Elliott, Suzanne; Griffin, Paul; Rockett, Rebecca; O'Rourke, Peter; Sloots, Theo; Angulo-Barturen, Iñigo; Ferrer, Santiago; Jiménez-Díaz, María Belén; Martínez, María-Santos; Hooft van Huijsduijnen, Rob; Duparc, Stephan; Leroy, Didier; Wells, Timothy N C; Baker, Mark; Möhrle, Jörg J

    2016-06-01

    Effective progression of candidate antimalarials is dependent on optimal dosing in clinical studies, which is determined by a sound understanding of pharmacokinetics and pharmacodynamics (PK/PD). Recently, two important translational models for antimalarials have been developed: the NOD/SCID/IL2Rγ(-/-) (NSG) model, whereby mice are engrafted with noninfected and Plasmodium falciparum-infected human erythrocytes, and the induced blood-stage malaria (IBSM) model in human volunteers. The antimalarial mefloquine was used to directly measure the PK/PD in both models, which were compared to previously published trial data for malaria patients. The clinical part was a single-center, controlled study using a blood-stage Plasmodium falciparum challenge inoculum in volunteers to characterize the effectiveness of mefloquine against early malaria. The study was conducted in three cohorts (n = 8 each) using different doses of mefloquine. The characteristic delay in onset of action of about 24 h was seen in both NSG and IBSM systems. In vivo 50% inhibitory concentrations (IC50s) were estimated at 2.0 μg/ml and 1.8 μg/ml in the NSG and IBSM models, respectively, aligning with 1.8 μg/ml reported previously for patients. In the IBSM model, the parasite reduction ratios were 157 and 195 for the 10- and 15-mg/kg doses, within the range of previously reported clinical data for patients but significantly lower than observed in the mouse model. Linking mouse and human challenge models to clinical trial data can accelerate the accrual of critical data on antimalarial drug activity. Such data can guide large clinical trials required for development of urgently needed novel antimalarial combinations. (This trial was registered at the Australian New Zealand Clinical Trials Registry [http://anzctr.org.au] under registration number ACTRN12612000323820.). PMID:27044554

  1. High IFN-gamma and TNF production by peripheral NK cells of Colombian patients with different clinical presentation of Plasmodium falciparum

    PubMed Central

    2012-01-01

    Background In Colombia, Plasmodium falciparum infection rarely results in severe disease or mortality compared to infections in African populations. During natural infection NK cells exhibit a cytolytic effect and regulate dendritic cells, macrophages, neutrophils as well as affect antigen specific T and B cell responses. To characterize the NK cells in P. falciparum infected patients of a highly endemic region of Colombia, the degree of NK proliferation and production of IFN gamma and TNF production in these cells were explored. Methods Seventeen patients with acute and three with severe P. falciparum malaria patients from the Northwest region of the country were recruited in the study. In addition, 20 healthy controls were included: 10 from Medellin (no-transmission area) and 10 from the Uraba region (a malaria endemic area). Immunophenotypic analysis of peripheral mononuclear cells was performed by FACS to detect total number of NK cells, subtypes and intracellular IFNγ and TNF production by NK cells in the different patient groups. Results The total mean CD56+/CD3- NK cell proportions in acute and severe malaria subjects were 9.14% (7.15%CD56dim, 2.01%CD56bright) and 19.62% (16.05%CD56dim, 3.58%CD56bright), respectively, in contrast to healthy controls from endemic (total mean CD56+/CD3-1.2%) and non-endemic area (total mean CD56+/CD3- 0.67%). Analysis of basal IFNγ and TNF levels confirmed the CD56bright NK population as the main cytokine producer (p < 0.0001) in the groups affected with malaria, with the CD56dim NK cell exhibiting the highest potential of TNF production after stimulus in the acute malaria group. Conclusions The results confirm the important role of not only CD56bright but also of CD56dim NK cell populations as producers of the two cytokines in malaria patients in Colombia. PMID:22316273

  2. A Reduced Risk of Infection with Plasmodium vivax and Clinical Protection against Malaria Are Associated with Antibodies against the N Terminus but Not the C Terminus of Merozoite Surface Protein 1†

    PubMed Central

    Nogueira, Paulo Afonso; Piovesan Alves, Fabiana; Fernandez-Becerra, Carmen; Pein, Oliver; Rodrigues Santos, Neida; Pereira da Silva, Luiz Hildebrando; Plessman Camargo, Erney; del Portillo, Hernando A.

    2006-01-01

    Progress towards the development of a malaria vaccine against Plasmodium vivax, the most widely distributed human malaria parasite, will require a better understanding of the immune responses that confer clinical protection to patients in regions where malaria is endemic. The occurrence of clinical protection in P. vivax malaria in Brazil was first reported among residents of the riverine community of Portuchuelo, in Rondônia, western Amazon. We thus analyzed immune sera from this same human population to determine if naturally acquired humoral immune responses against the merozoite surface protein 1 of P. vivax, PvMSP1, could be associated with reduced risk of infection and/or clinical protection. Our results demonstrated that this association could be established with anti-PvMSP1 antibodies predominantly of the immunoglobulin G3 subclass directed against the N terminus but not against the C terminus, in spite of the latter being more immunogenic and capable of natural boosting. This is the first report of a prospective study of P. vivax malaria demonstrating an association of reduced risk of infection and clinical protection with antibodies against an antigen of this parasite. PMID:16622209

  3. High Rates of Asymptomatic, Sub-microscopic Plasmodium vivax Infection and Disappearing Plasmodium falciparum Malaria in an Area of Low Transmission in Solomon Islands

    PubMed Central

    Waltmann, Andreea; Darcy, Andrew W.; Harris, Ivor; Koepfli, Cristian; Lodo, John; Vahi, Ventis; Piziki, David; Shanks, G. Dennis; Barry, Alyssa E.; Whittaker, Maxine; Kazura, James W.; Mueller, Ivo

    2015-01-01

    Introduction Solomon Islands is intensifying national efforts to achieve malaria elimination. A long history of indoor spraying with residual insecticides, combined recently with distribution of long lasting insecticidal nets and artemether-lumefantrine therapy, has been implemented in Solomon Islands. The impact of these interventions on local endemicity of Plasmodium spp. is unknown. Methods In 2012, a cross-sectional survey of 3501 residents of all ages was conducted in Ngella, Central Islands Province, Solomon Islands. Prevalence of Plasmodium falciparum, P. vivax, P. ovale and P. malariae was assessed by quantitative PCR (qPCR) and light microscopy (LM). Presence of gametocytes was determined by reverse transcription quantitative PCR (RT-qPCR). Results By qPCR, 468 Plasmodium spp. infections were detected (prevalence = 13.4%; 463 P. vivax, five mixed P. falciparum/P. vivax, no P. ovale or P. malariae) versus 130 by LM (prevalence = 3.7%; 126 P. vivax, three P. falciparum and one P. falciparum/P. vivax). The prevalence of P. vivax infection varied significantly among villages (range 3.0–38.5%, p<0.001) and across age groups (5.3–25.9%, p<0.001). Of 468 P. vivax infections, 72.9% were sub-microscopic, 84.5% afebrile and 60.0% were both sub-microscopic and afebrile. Local residency, low education level of the household head and living in a household with at least one other P. vivax infected individual increased the risk of P. vivax infection. Overall, 23.5% of P. vivax infections had concurrent gametocytaemia. Of all P. vivax positive samples, 29.2% were polyclonal by MS16 and msp1F3 genotyping. All five P. falciparum infections were detected in residents of the same village, carried the same msp2 allele and four were positive for P. falciparum gametocytes. Conclusion P. vivax infection remains endemic in Ngella, with the majority of cases afebrile and below the detection limit of LM. P. falciparum has nearly disappeared, but the risk of re-introductions and

  4. Age-Stratified Profiles of Serum IL-6, IL-10, and TNF-α Cytokines among Kenyan Children with Schistosoma haematobium, Plasmodium falciparum, and Other Chronic Parasitic Co-infections

    PubMed Central

    Bustinduy, Amaya L.; Sutherland, Laura J.; Chang-Cojulun, Alicia; Malhotra, Indu; DuVall, Adam S.; Fairley, Jessica K.; Mungai, Peter L.; Muchiri, Eric M.; Mutuku, Francis M.; Kitron, Uriel; King, Charles H.

    2015-01-01

    In a study of children having polyparasitic infections in a Schistosoma haematobium–endemic area, we examined the hypothesis that S. haematobium–positive children, compared with S. haematobium–negative children (anti-soluble worm antigen preparation [SWAP] negative and egg negative) have increased systemic production of pro-inflammatory cytokines (interleukin [IL]-6, tumor necrosis factor [TNF]-α) and decreased down-regulatory IL-10. A total of 804 children, 2–19 years of age, were surveyed between July and December 2009 and tested for S. haematobium, Plasmodium falciparum, filariasis, and soil-transmitted helminth infections. Plasma levels of IL-6, TNF-α, and IL-10 were compared for S. haematobium–positive and S. haematobium–negative children, adjusting for malaria, filaria, and hookworm co-infections, and for nutritional status, age group, sex, and geographic location. IL-10 was significantly elevated among children infected with S. haematobium, showing bimodal peaks in 7–8 and 13–14 years age groups. IL-10 was also higher among children who were acutely malnourished, whereas IL-10 levels were lower in the presence of S. haematobium–filaria co-infection. After adjustment for co-factors, IL-6 was significantly elevated among children of 5–6 years and among those with P. falciparum infection. Lower levels of IL-6 were found in malaria–hookworm co-infection. High levels of TNF-α were found in children aged 11–12 years regardless of infection status. In addition, village of residence was a strong predictor of IL-6 and IL-10 plasma levels. In adolescent children infected with S. haematobium, there is an associated elevation in circulating IL-10 that may reduce the risk of later morbidity. Although we did not find a direct link between S. haematobium infection and circulating pro-inflammatory IL-6 and TNF-α levels, future T-cell stimulation studies may provide more conclusive linkages between infection and cytokine responses in settings that

  5. Reduced Risk of Plasmodium vivax Malaria in Papua New Guinean Children with Southeast Asian Ovalocytosis in Two Cohorts and a Case-Control Study

    PubMed Central

    Manning, Laurens; Rarau, Patricia; Laman, Moses; Senn, Nicolas; Grimberg, Brian T.; Tavul, Livingstone; Stanisic, Danielle I.; Robinson, Leanne J.; Aponte, John J.; Dabod, Elijah; Reeder, John C.; Siba, Peter; Zimmerman, Peter A.; Davis, Timothy M. E.; King, Christopher L.; Michon, Pascal; Mueller, Ivo

    2012-01-01

    Background The erythrocyte polymorphism, Southeast Asian ovalocytosis (SAO) (which results from a 27-base pair deletion in the erythrocyte band 3 gene, SLC4A1Δ27) protects against cerebral malaria caused by Plasmodium falciparum; however, it is unknown whether this polymorphism also protects against P. vivax infection and disease. Methods and Findings The association between SAO and P. vivax infection was examined through genotyping of 1,975 children enrolled in three independent epidemiological studies conducted in the Madang area of Papua New Guinea. SAO was associated with a statistically significant 46% reduction in the incidence of clinical P. vivax episodes (adjusted incidence rate ratio [IRR] = 0.54, 95% CI 0.40–0.72, p<0.0001) in a cohort of infants aged 3–21 months and a significant 52% reduction in P. vivax (blood-stage) reinfection diagnosed by PCR (95% CI 22–71, p = 0.003) and 55% by light microscopy (95% CI 13–77, p = 0.014), respectively, in a cohort of children aged 5–14 years. SAO was also associated with a reduction in risk of P. vivax parasitaemia in children 3–21 months (1,111/µl versus 636/µl, p = 0.011) and prevalence of P. vivax infections in children 15–21 months (odds ratio [OR] = 0.39, 95% CI 0.23–0.67, p = 0.001). In a case-control study of children aged 0.5–10 years, no child with SAO was found among 27 cases with severe P. vivax or mixed P. falciparum/P. vivax malaria (OR = 0, 95% CI 0–1.56, p = 0.11). SAO was associated with protection against severe P. falciparum malaria (OR = 0.38, 95% CI 0.15–0.87, p = 0.014) but no effect was seen on either the risk of acquiring blood-stage infections or uncomplicated episodes with P. falciparum. Although Duffy antigen receptor expression and function were not affected on SAO erythrocytes compared to non-SAO children, high level (>90% binding inhibition) P. vivax Duffy binding protein–specific binding inhibitory antibodies were

  6. Revealing the Sequence and Resulting Cellular Morphology of Receptor-Ligand Interactions during Plasmodium falciparum Invasion of Erythrocytes

    PubMed Central

    Weiss, Greta E.; Gilson, Paul R.; Taechalertpaisarn, Tana; Tham, Wai-Hong; de Jong, Nienke W. M.; Harvey, Katherine L.; Fowkes, Freya J. I.; Barlow, Paul N.; Rayner, Julian C.; Wright, Gavin J.; Cowman, Alan F.; Crabb, Brendan S.

    2015-01-01

    During blood stage Plasmodium falciparum infection, merozoites invade uninfected erythrocytes via a complex, multistep process involving a series of distinct receptor-ligand binding events. Understanding each element in this process increases the potential to block the parasite’s life cycle via drugs or vaccines. To investigate specific receptor-ligand interactions, they were systematically blocked using a combination of genetic deletion, enzymatic receptor cleavage and inhibition of binding via antibodies, peptides and small molecules, and the resulting temporal changes in invasion and morphological effects on erythrocytes were filmed using live cell imaging. Analysis of the videos have shown receptor-ligand interactions occur in the following sequence with the following cellular morphologies; 1) an early heparin-blockable interaction which weakly deforms the erythrocyte, 2) EBA and PfRh ligands which strongly deform the erythrocyte, a process dependant on the merozoite’s actin-myosin motor, 3) a PfRh5-basigin binding step which results in a pore or opening between parasite and host through which it appears small molecules and possibly invasion components can flow and 4) an AMA1–RON2 interaction that mediates tight junction formation, which acts as an anchor point for internalization. In addition to enhancing general knowledge of apicomplexan biology, this work provides a rational basis to combine sequentially acting merozoite vaccine candidates in a single multi-receptor-blocking vaccine. PMID:25723550

  7. Plasmodium falciparum malaria in the Peruvian Amazon, a region of low transmission, is associated with immunologic memory.

    PubMed

    Clark, Eva H; Silva, Claudia J; Weiss, Greta E; Li, Shanping; Padilla, Carlos; Crompton, Peter D; Hernandez, Jean N; Branch, OraLee H

    2012-04-01

    The development of clinical immunity to Plasmodium falciparum malaria is thought to require years of parasite exposure, a delay often attributed to difficulties in developing protective antibody levels. In this study, we evaluated several P. falciparum vaccine candidate antigens, including apical membrane antigen 1 (AMA-1), circumsporozoite protein (CSP), erythrocyte binding antigen 175 (EBA-175), and the 19-kDa region of merozoite surface protein 1 (MSP1(19)). After observing a more robust antibody response to MSP1(19), we evaluated the magnitude and longevity of IgG responses specific to this antigen in Peruvian adults and children before, during, and after P. falciparum infection. In this low-transmission region, even one reported prior infection was sufficient to produce a positive anti-MSP1(19) IgG response for >5 months in the absence of reinfection. We also observed an expansion of the total plasmablast (CD19(+) CD27(+) CD38(high)) population in the majority of individuals shortly after infection and detected MSP1-specific memory B cells in a subset of individuals at various postinfection time points. This evidence supports our hypothesis that effective antimalaria humoral immunity can develop in low-transmission regions.

  8. Hidden Plasmodium falciparum parasites in human infections: different genotype distribution in the peripheral circulation and in the placenta.

    PubMed

    Schleiermacher, Dietlind; Le Hesran, Jean-Yves; Ndiaye, Jean-Louis; Perraut, Ronald; Gaye, Alioune; Mercereau-Puijalon, Odile

    2002-12-01

    Sequestration of the mature Plasmodium falciparum forms complicates detection, quantification and molecular analysis of human infections. Whether the circulating parasites represent all or only a subset of co-infecting genotypes is unclear. We have investigated this issue and compared placenta and peripheral blood msp1 and msp2 genotypes in 58 women delivering with an ICT-positive placenta in Guediawaye, Senegal. Most placenta (91%) and blood samples (98%) were multiply infected. Multiplicity of infection was positively correlated in both tissues. However, the placental and circulating genotype profiles differed markedly. Only 10% of matched peripheral blood/placenta samples had identical genotypes, whereas 74% had only partially concordant genotypes, with some alleles detected in both tissues, together with additional allele(s) detected in one tissue only. Eight women (14%) had totally discordant placental and peripheral blood genotypes. Thus, in the vast majority of cases, some sequestered genotypes remain hidden, undetected in the peripheral circulation, indicating that analysis of peripheral parasites generates a partial picture of a P. falciparum infection.

  9. Type of in vitro cultivation influences cytoadhesion, knob structure, protein localization and transcriptome profile of Plasmodium falciparum

    PubMed Central

    Tilly, Ann-Kathrin; Thiede, Jenny; Metwally, Nahla; Lubiana, Pedro; Bachmann, Anna; Roeder, Thomas; Rockliffe, Nichola; Lorenzen, Stephan; Tannich, Egbert; Gutsmann, Thomas; Bruchhaus, Iris

    2015-01-01

    In vitro cultivation of Plasmodium falciparum is critical for studying the biology of this parasite. However, it is likely that different in vitro cultivation conditions influence various aspects of the parasite’s life cycle. In the present study two P. falciparum isolates were cultivated using the two most common methods, in which AlbuMAX or human serum as additives are used, and the results were compared. The type of cultivation influenced the knob structure of P. falciparum-infected erythrocytes (IEs). IEs cultivated with AlbuMAX had fewer knobs than those cultivated with human serum. Furthermore, knob size varied between isolates and is also depended on the culture medium. In addition, there was a greater reduction in the cytoadhesion of IEs to various endothelial receptors in the presence of AlbuMAX than in the presence of human serum. Surprisingly, cytoadhesion did not correlate with the presence or absence of knobs. Greater numbers of the variant surface antigen families RIFIN, STEVOR, and PfMC-2TM were found at the IE membrane when cultivated in the presence of AlbuMAX. Moreover, the type of cultivation had a marked influence on the transcriptome profile. Compared with cultivation with human serum, cultivation with AlbuMAX increased the expression of approximately 500–870 genes. PMID:26568166

  10. Haemoglobin-E in the presence of oxidative substances from fava bean may be protective against Plasmodium falciparum malaria.

    PubMed

    Kitayaporn, D; Nelson, K E; Charoenlarp, P; Pholpothi, T

    1992-01-01

    A case-control study was carried out at a community hospital in eastern Thailand in order to study the association between haemoglobin E and Plasmodium falciparum malaria; 271 P. falciparum cases and 271 controls were enrolled. After adjusting for age, sex, time since last malaria attack, history of mosquito net use, and history of fava bean consumption in the previous month, neither heterozygous nor homozygous haemoglobin E provided significant protection against P. falciparum infection, with odds ratios (OR) = 0.91 (95% confidence limits = 0.61, 1.36) and 0.78 (0.34, 1.82) respectively when compared to persons with haemoglobin A who were not consumers of fava beans. However, haemoglobin E carriers who ate fava beans were significantly protected against P. falciparum malaria with OR = 0.26 (0.09, 0.76) and OR = 0.001 (0.00, 1120.59) for subjects with heterozygous and homozygous haemoglobin E, respectively. The study suggests a possible synergistic protective effect of haemoglobin E on the risk of P. falciparum malaria in subjects who have consumed fava beans.

  11. Haemoglobin-E in the presence of oxidative substances from fava bean may be protective against Plasmodium falciparum malaria.

    PubMed

    Kitayaporn, D; Nelson, K E; Charoenlarp, P; Pholpothi, T

    1992-01-01

    A case-control study was carried out at a community hospital in eastern Thailand in order to study the association between haemoglobin E and Plasmodium falciparum malaria; 271 P. falciparum cases and 271 controls were enrolled. After adjusting for age, sex, time since last malaria attack, history of mosquito net use, and history of fava bean consumption in the previous month, neither heterozygous nor homozygous haemoglobin E provided significant protection against P. falciparum infection, with odds ratios (OR) = 0.91 (95% confidence limits = 0.61, 1.36) and 0.78 (0.34, 1.82) respectively when compared to persons with haemoglobin A who were not consumers of fava beans. However, haemoglobin E carriers who ate fava beans were significantly protected against P. falciparum malaria with OR = 0.26 (0.09, 0.76) and OR = 0.001 (0.00, 1120.59) for subjects with heterozygous and homozygous haemoglobin E, respectively. The study suggests a possible synergistic protective effect of haemoglobin E on the risk of P. falciparum malaria in subjects who have consumed fava beans. PMID:1412643

  12. Induction of adhesion-inhibitory antibodies against placental Plasmodium falciparum parasites by using single domains of VAR2CSA.

    PubMed

    Nielsen, Morten A; Pinto, Vera V; Resende, Mafalda; Dahlbäck, Madeleine; Ditlev, Sisse B; Theander, Thor G; Salanti, Ali

    2009-06-01

    In areas of endemicity pregnancy-associated malaria is an important cause of maternal anemia, stillbirth, and delivery of low-birth-weight children. The syndrome is precipitated by the accumulation of Plasmodium falciparum-infected erythrocytes in the placenta, mediated through an interaction between a parasite protein expressed on erythrocytes named variant surface antigen 2-chondroitin sulfate A (VAR2CSA) and CSA on syncytiotrophoblasts. VAR2CSA is a large polymorphic protein consisting of six Duffy binding-like (DBL), domains and with current constraints on recombinant protein production it is not possible to produce entire VAR2CSA recombinant proteins. Furthermore, the presence of polymorphisms has raised the question of whether it is feasible to define VAR2CSA antigens eliciting broadly protective antibodies. Thus, the challenge for vaccine development is to define smaller parts of the molecule which induce antibodies that inhibit CSA binding of different parasite strains. In this study, we produced a large panel of VAR2CSA proteins and raised antibodies against these antigens. We show that antibodies against the DBL4 domain effectively inhibit parasite binding. As the inhibition was not limited to homologous parasite strains, it seems feasible to base a protective malaria vaccine on a single VAR2CSA DBL domain. PMID:19307213

  13. Contrasting Patterns of Serologic and Functional Antibody Dynamics to Plasmodium falciparum Antigens in a Kenyan Birth Cohort

    PubMed Central

    Malhotra, Indu; Wang, Xuelie; Babineau, Denise; Yeo, Kee Thai; Anderson, Timothy; Kimmel, Rhonda J.; Angov, Evelina; Lanar, David E.; Narum, David; Dutta, Sheetij; Richards, Jack; Beeson, James G.; Crabb, Brendan S.; Cowman, Alan F.; Horii, Toshihiro; Muchiri, Eric; Mungai, Peter L.; King, Christopher L.; Kazura, James W.

    2015-01-01

    IgG antibodies to Plasmodium falciparum are transferred from the maternal to fetal circulation during pregnancy, wane after birth, and are subsequently acquired in response to natural infection. We examined the dynamics of malaria antibody responses of 84 Kenyan infants from birth to 36 months of age by (i) serology, (ii) variant surface antigen (VSA) assay, (iii) growth inhibitory activity (GIA), and (iv) invasion inhibition assays (IIA) specific for merozoite surface protein 1 (MSP1) and sialic acid-dependent invasion pathway. Maternal antibodies in each of these four categories were detected in cord blood and decreased to their lowest level by approximately 6 months of age. Serologic antibodies to 3 preerythrocytic and 10 blood-stage antigens subsequently increased, reaching peak prevalence by 36 months. In contrast, antibodies measured by VSA, GIA, and IIA remained low even up to 36 months. Infants sensitized to P. falciparum in utero, defined by cord blood lymphocyte recall responses to malaria antigens, acquired antimalarial antibodies at the same rate as those who were not sensitized in utero, indicating that fetal exposure to malaria antigens did not affect subsequent infant antimalarial responses. Infants with detectable serologic antibodies at 12 months of age had an increased risk of P. falciparum infection during the subsequent 24 months. We conclude that serologic measures of antimalarial antibodies in children 36 months of age or younger represent biomarkers of malaria exposure rather than protection and that functional antibodies develop after 36 months of age in this population. PMID:26656119

  14. Plasmodium falciparum is dependent on de novo myo-inositol biosynthesis for assembly of GPI glycolipids and infectivity.

    PubMed

    Macrae, James I; Lopaticki, Sash; Maier, Alexander G; Rupasinghe, Thusitha; Nahid, Amsha; Cowman, Alan F; McConville, Malcolm J

    2014-02-01

    Intra-erythrocytic stages of the malaria parasite, Plasmodium falciparum, are thought to be dependent on de novo synthesis of phosphatidylinositol, as red blood cells (RBC) lack the capacity to synthesize this phospholipid. The myo-inositol headgroup of PI can either be synthesized de novo or scavenged from the RBC. An untargeted metabolite profiling of P. falciparum infected RBC showed that trophozoite and schizont stages accumulate high levels of myo-inositol-3-phosphate, indicating increased de novo biosynthesis of myo-inositol from glucose 6-phosphate. Metabolic labelling studies with (13) C-U-glucose in the presence and absence of exogenous inositol confirmed that de novo myo-inositol synthesis occurs in parallel with myo-inositol salvage pathways. Unexpectedly, while both endogenous and scavenged myo-inositol was used to synthesize bulk PI, only de novo-synthesized myo-inositol was incorporated into GPI glycolipids. Moreover, gene disruption studies suggested that the INO1 gene, encoding myo-inositol 3-phosphate synthase, is essential in asexual parasite stages. Together these findings suggest that P. falciparum asexual stages are critically dependent on de novo myo-inositol biosynthesis for assembly of a sub-pool of PI species and GPI biosynthesis. These findings highlight unexpected complexity in phospholipid biosynthesis in P. falciparum and a lack of redundancy in some nutrient salvage versus endogenous biosynthesis pathways.

  15. Comparative sequence analysis of domain I of Plasmodium falciparum apical membrane antigen 1 from Saudi Arabia and worldwide isolates.

    PubMed

    Al-Qahtani, Ahmed A; Abdel-Muhsin, Abdel-Muhsin A; Bin Dajem, Saad M; AlSheikh, Adel Ali H; Bohol, Marie Fe F; Al-Ahdal, Mohammed N; Putaporntip, Chaturong; Jongwutiwes, Somchai

    2016-04-01

    The apical membrane antigen 1 of Plasmodium falciparum (PfAMA1) plays a crucial role in erythrocyte invasion and is a target of protective antibodies. Although domain I of PfAMA1 has been considered a promising vaccine component, extensive sequence diversity in this domain could compromise an effective vaccine design. To explore the extent of sequence diversity in domain I of PfAMA1, P. falciparum-infected blood samples from Saudi Arabia collected between 2007 and 2009 were analyzed and compared with those from worldwide parasite populations. Forty-six haplotypes and a novel codon change (M190V) were found among Saudi Arabian isolates. The haplotype diversity (0.948±0.004) and nucleotide diversity (0.0191±0.0008) were comparable to those from African hyperendemic countries. Positive selection in domain I of PfAMA1 among Saudi Arabian parasite population was observed because nonsynonymous nucleotide substitutions per nonsynonymous site (dN) significantly exceeded synonymous nucleotide substitutions per synonymous site (dS) and Tajima's D and its related statistics significantly deviated from neutrality in the positive direction. Despite a relatively low prevalence of malaria in Saudi Arabia, a minimum of 17 recombination events occurred in domain I. Genetic differentiation was significant between P. falciparum in Saudi Arabia and parasites from other geographic origins. Several shared or closely related haplotypes were found among parasites from different geographic areas, suggesting that vaccine derived from multiple shared epitopes could be effective across endemic countries.

  16. Inhibition of malaria parasite Plasmodium falciparum development by crotamine, a cell penetrating peptide from the snake venom.

    PubMed

    El Chamy Maluf, S; Dal Mas, C; Oliveira, E B; Melo, P M; Carmona, A K; Gazarini, M L; Hayashi, M A F

    2016-04-01

    We show here that crotamine, a polypeptide from the South American rattlesnake venom with cell penetrating and selective anti-fungal and anti-tumoral properties, presents a potent anti-plasmodial activity in culture. Crotamine inhibits the development of the Plasmodium falciparum parasites in a dose-dependent manner [IC50 value of 1.87 μM], and confocal microscopy analysis showed a selective internalization of fluorescent-labeled crotamine into P. falciparum infected erythrocytes, with no detectable fluorescence in uninfected healthy erythrocytes. In addition, similarly to the crotamine cytotoxic effects, the mechanism underlying the anti-plasmodial activity may involve the disruption of parasite acidic compartments H(+) homeostasis. In fact, crotamine promoted a reduction of parasites organelle fluorescence loaded with the lysosomotropic fluorochrome acridine orange, in the same way as previously observed mammalian tumoral cells. Taken together, we show for the first time crotamine not only compromised the metabolism of the P. falciparum, but this toxin also inhibited the parasite growth. Therefore, we suggest this snake polypeptide as a promising lead molecule for the development of potential new molecules, namely peptidomimetics, with selectivity for infected erythrocytes and ability to inhibit the malaria infection by its natural affinity for acid vesicles. PMID:26806200

  17. Naturally Acquired Antibody Responses to Plasmodium vivax and Plasmodium falciparum Merozoite Surface Protein 1 (MSP1) C-Terminal 19 kDa Domains in an Area of Unstable Malaria Transmission in Southeast Asia

    PubMed Central

    Wang, Qinghui; Zhao, Zhenjun; Zhang, Xuexing; Li, Xuelian; Zhu, Min; Li, Peipei; Yang, Zhaoqing; Wang, Ying; Yan, Guiyun; Shang, Hong; Cao, Yaming; Fan, Qi; Cui, Liwang

    2016-01-01

    Understanding naturally acquired immunity to infections caused by Plasmodia in different malaria endemicity settings is needed for better vaccine designs and for exploring antibody responses as a proxy marker of malaria transmission intensity. This study investigated the sero-epidemiology of malaria along the international border between China and Myanmar, where malaria elimination action plans are in place. This study recruited 233 P. vivax and 156 P. falciparum infected subjects with acute malaria at the malaria clinics and hospitals. In addition, 93 and 67 healthy individuals from the same endemic region or from non-endemic region, respectively, were used as controls. Acute malaria infections were identified by microscopy. Anti-recombinant PfMSP119 and PvMSP119 antibody levels were measured by ELISA. Antibody responses to respective MSP119 were detected in 50.9% and 78.2% patients with acute P. vivax and P. falciparum infections, respectively. There were cross-reacting antibodies in Plasmodium patients against these two recombinant proteins, though we could not exclude the possibility of submicroscopic mixed-species infections. IgG1, IgG3 and IgG4 were the major subclasses. Interestingly, 43.2% of the healthy endemic population also had antibodies against PfMSP119, whereas only 3.9% of this population had antibodies against PvMSP119. Higher antibody levels were correlated with age and parasite density, but not with season, gender or malaria history. Both total IgG and individual IgG subclasses underwent substantial declines during the convalescent period in three months. This study demonstrated that individuals in a hypoendemic area with coexistence of P. vivax and P. falciparum can mount rapid antibody responses against both PfMSP119 and PvMSP119. The significantly higher proportion of responders to PfMSP119 in the healthy endemic population indicates higher prevalence of P. falciparum in the recent past. Specific antibodies against PvMSP119 could serve as a

  18. A novel 70-kDa Triton X-114-soluble antigen of Plasmodium falciparum that contains interspecies-conserved epitopes.

    PubMed

    Ma, H W; Ray, P; Dhanda, V; Das, P K; Paliwal, S; Sahoo, N; Patra, K P; Das, L K; Singh, B; Kironde, F A

    1996-08-01

    In order to identify novel conserved integral membrane and other membrane-associated proteins of Plasmodium falciparum, lambda gt11-P. falciparum DNA library phages were immunoscreened with convalescent-phase mouse sera and rabbit antiserum against Triton X-114-soluble proteins of P. falciparum. One recombinant phage clone, L857, reacted with both of the antibody probes. Insert DNA (857 bp long) in L857 was 69% dA+dT rich and hybridized to a fragment of 1800 bp from mung bean nuclease-digested P. falciparum genomic DNA. The cloned parasite DNA did not show notable sequence homology with any known protein gene. The L857-encoded polypeptide, p34 (M(r) 34 kDa) was expressed in bacteria, fused to glutathione S-transferase (GST). The fusion peptide, GST-p34 (M(r) 62 kDa), was recognized by immune serum against Triton X-114-soluble antigens of P. falciparum and was reactive with anti-P. falciparum, anti-Plasmodium yoelii, and anti-GST sera. Rabbit antiserum raised against the fusion peptide recognized a 70-kDa protein from lysates of P. falciparum cells and a putative homologous 100-kDa protein from lysates of P. yoelii. The rabbit serum anti-fusion peptide antibodies bound to acetone-fixed P. falciparum-infected erythrocytes and, in immunofluorescent antibody tests, produced a punctate pattern of fluorescence suggesting that the 70-kDa native protein is associated with an apical organelle of the parasite.

  19. Soluble recombinant merozoite surface antigen-142kDa of Plasmodium vivax: An improved diagnostic antigen for vivax malaria.

    PubMed

    Mirahmadi, Hadi; Fallahi, Shirzad; Seyyed Tabaei, Seyyed Javad

    2016-04-01

    Enzyme Linked Immunosorbent Assay (ELISA), as a serological test, can be a beneficial tool for epidemiological studies by screening blood donors and diagnosis of specific antibodies from Plasmodium vivax (P. vivax) infected cases. Since P. vivax cannot easily be acquired in vitro, ELISA assays using total or semi-purified antigens are seldom used. On the basis of this restriction, we examined whether recombinant protein 42 kDa related to C-terminal region of the merozoite surface antigen-1 of P. vivax (MSA-1(42)) could be suitable for serological detection of vivax malaria infection. Purified recombinant protein produced in Escherichia coli (E. coli) (GST-MSA-1(42)) was examined for its ability to bind to IgG antibodies of individuals with patent P. vivax infection. The method was tested with 262 serum samples collected from individuals living in the south and southeastern regions of Iran where malaria is endemic. Samples exposed to Plasmodium falciparum (P. falciparum) infection and patients with other infectious disease (toxoplasmosis, Leishmania infantum infection, echinococcosis and FUO (fever with unknown origin)) except for P. falciparum were residing in non- malaria endemic areas in Iran. Generally, the sensitivity of ELISA evaluated with sera from naturally infected individuals was 86.9%. The specificity value of the ELISA determined with sera from healthy individuals and from individuals with other infectious diseases was 94.05%. The positive predictive value (PPV), negative predictive value (NPV) provided, and the diagnostic efficiency of anti-rPvMSA-1(42) antibody using indirect ELISA were determined 93.58, 87.77 and 91.06% respectively. Our study demonstrated that, because MSA-1(42) kDa contains both the 33 and 19 kDa fragments in its structure, it can serve as the basis for the development of a sensitive serological test which can be used for epidemiological studies, screening blood donors and diagnosis of P. vivax malaria. PMID:26851675

  20. Evidence for the Contribution of the Hemozoin Synthesis Pathway of the Murine Plasmodium yoelii to the Resistance to Artemisinin-Related Drugs

    PubMed Central

    Nicolau-Travers, Marie-Laure; Iriart, Xavier; Njomnang Soh, Patrice; Bousejra-ElGarah, Fatima; Meunier, Bernard; Berry, Antoine; Benoit-Vical, Françoise

    2012-01-01

    Plasmodium falciparum malaria is a major global health problem, causing approximately 780,000 deaths each year. In response to the spreading of P. falciparum drug resistance, WHO recommended in 2001 to use artemisinin derivatives in combination with a partner drug (called ACT) as first-line treatment for uncomplicated falciparum malaria, and most malaria-endemic countries have since changed their treatment policies accordingly. Currently, ACT are often the last treatments that can effectively and rapidly cure P. falciparum infections permitting to significantly decrease the mortality and the morbidity due to malaria. However, alarming signs of emerging resistance to artemisinin derivatives along the Thai-Cambodian border are of major concern. Through long-term in vivo pressures, we have been able to select a murine malaria model resistant to artemisinins. We demonstrated that the resistance of Plasmodium to artemisinin-based compounds depends on alterations of heme metabolism and on a loss of hemozoin formation linked to the down-expression of the recently identified Heme Detoxification Protein (HDP). These artemisinins resistant strains could be able to detoxify the free heme by an alternative catabolism pathway involving glutathione (GSH)-mediation. Finally, we confirmed that artemisinins act also like quinolines against Plasmodium via hemozoin production inhibition. The work proposed here described the mechanism of action of this class of molecules and the resistance to artemisinins of this model. These results should help both to reinforce the artemisinins activity and avoid emergence and spread of endoperoxides resistance by focusing in adequate drug partners design. Such considerations appear crucial in the current context of early artemisinin resistance in Asia. PMID:22403683

  1. A spiral scaffold underlies cytoadherent knobs in Plasmodium falciparum–infected erythrocytes

    PubMed Central

    Watermeyer, Jean M.; Hale, Victoria L.; Hackett, Fiona; Clare, Daniel K.; Cutts, Erin E.; Vakonakis, Ioannis; Fleck, Roland A.; Blackman, Michael J.

    2016-01-01

    Much of the virulence of Plasmodium falciparum malaria is caused by cytoadherence of infected erythrocytes, which promotes parasite survival by preventing clearance in the spleen. Adherence is mediated by membrane protrusions known as knobs, whose formation depends on the parasite-derived, knob-associated histidine-rich protein (KAHRP). Knobs are required for cytoadherence under flow conditions, and they contain both KAHRP and the parasite-derived erythrocyte membrane protein PfEMP1. Using electron tomography, we have examined the 3-dimensional structure of knobs in detergent-insoluble skeletons of P falciparum 3D7 schizonts. We describe a highly organized knob skeleton composed of a spiral structure coated by an electron-dense layer underlying the knob membrane. This knob skeleton is connected by multiple links to the erythrocyte cytoskeleton. We used immuno-electron microscopy (EM) to locate KAHRP in these structures. The arrangement of membrane proteins in the knobs, visualized by high-resolution freeze-fracture scanning EM, is distinct from that in the surrounding erythrocyte membrane, with a structure at the apex that likely represents the adhesion site. Thus, erythrocyte knobs in P falciparum infection contain a highly organized skeleton structure underlying a specialized region of membrane. We propose that the spiral and dense coat organize the cytoadherence structures in the knob, and anchor them into the erythrocyte cytoskeleton. The high density of knobs and their extensive mechanical linkage suggest an explanation for the rigidification of the cytoskeleton in infected cells, and for the transmission to the cytoskeleton of shear forces experienced by adhering cells. PMID:26637786

  2. Long term persistence of clonal malaria parasite Plasmodium falciparum lineages in the Colombian Pacific region

    PubMed Central

    2013-01-01

    Background Resistance to chloroquine and antifolate drugs has evolved independently in South America, suggesting that genotype - phenotype studies aimed at understanding the genetic basis of resistance to these and other drugs should be conducted in this continent. This research was conducted to better understand the population structure of Colombian Plasmodium falciparum in preparation for such studies. Results A set of 384 SNPs were genotyped in blood spot DNA samples from 447 P. falciparum infected subjects collected over a ten year period from four provinces of the Colombian Pacific coast to evaluate clonality, population structure and linkage disequilibrium (LD). Most infections (81%) contained a single predominant clone. These clustered into 136 multilocus genotypes (MLGs), with 32% of MLGs recovered from multiple (2 – 28) independent subjects. We observed extremely low genotypic richness (R = 0.42) and long persistence of MLGs through time (median = 537 days, range = 1 – 2,997 days). There was a high probability (>5%) of sampling parasites from the same MLG in different subjects within 28 days, suggesting caution is needed when using genotyping methods to assess treatment success in clinical drug trials. Panmixia was rejected as four well differentiated subpopulations (FST = 0.084 - 0.279) were identified. These occurred sympatrically but varied in frequency within the four provinces. Linkage disequilibrium (LD) decayed more rapidly (r2 = 0.17 for markers <10 kb apart) than observed previously in South American samples. Conclusions We conclude that Colombian populations have several advantages for association studies, because multiple clone infections are uncommon and LD decays over the scale of one or a few genes. However, the extensive population structure and low genotype richness will need to be accounted for when designing and analyzing association studies. PMID:23294725

  3. Plasmodium falciparum: genetic diversity and complexity of infections in an isolated village in western Thailand.

    PubMed

    Tanabe, Kazuyuki; Zollner, Gabriela; Vaughan, Jefferson A; Sattabongkot, Jetsumon; Khuntirat, Benjawan; Honma, Hajime; Mita, Toshihiro; Tsuboi, Takafumi; Coleman, Russell

    2015-06-01

    Genetic diversity of Plasmodium falciparum is intimately associated with morbidity, mortality and malaria control strategies. It is therefore imperative to study genetic makeup and population structure of this parasite in endemic areas. In Kong Mong Tha, an isolated village in western Thailand, the majority of P. falciparum infections are asymptomatic. In this study we investigated complexity of infections and single nucleotide polymorphisms (SNPs) in the P. falciparum population of Kong Mong Tha, and compared results with those previously obtained from Mae Sod, in northwestern Thailand, where the majority of infections were symptomatic. Using PCR-based determination of the 5' merozoite surface protein 1 gene (msp1) recombinant types, we found that 39% of 59 P. falciparum isolates from Kong Mong Tha had multiple 5' recombinant types with a mean number of 1.54. These values were much lower than those obtained from Mae Sod: 96% for multiple infections and with a mean number of 3.61. Analysis of full-length sequences of two housekeeping genes, the P-type Ca(2+)-transporting ATPase gene (n=33) plus adenylosuccinate lyase gene (n=33), and three vaccine candidate antigen genes, msp1 (n=26), the circumsporozoite protein gene, csp (n=30) and the apical membrane antigen 1 gene, ama 1 (n=32), revealed that in all of these genes within-population SNP diversity was at similar levels between Kong Mong Tha and Mae Sod, suggesting that the extent of MOI and clinical manifestations of malaria are not strongly associated with genetic diversity. Additionally, we did not detect significant genetic differentiation between the two parasite populations, as estimated by the Wright's fixation index of inter-population variance in allele frequencies, suggesting that gene flow prevented the formation of population structuring. Thus, this study highlights unique features of P. falciparum populations in Thailand. The implications of these finding are discussed.

  4. Serological Conservation of Parasite-Infected Erythrocytes Predicts Plasmodium falciparum Erythrocyte Membrane Protein 1 Gene Expression but Not Severity of Childhood Malaria.

    PubMed

    Warimwe, George M; Abdi, Abdirahman I; Muthui, Michelle; Fegan, Gregory; Musyoki, Jennifer N; Marsh, Kevin; Bull, Peter C

    2016-05-01

    Plasmodium falciparum erythrocyte membrane protein 1 (PfEMP1), expressed on P. falciparum-infected erythrocytes, is a major family of clonally variant targets of naturally acquired immunity to malaria. Previous studies have demonstrated that in areas where malaria is endemic, antibodies to infected erythrocytes from children with severe malaria tend to be more seroprevalent than antibodies to infected erythrocytes from children with nonsevere malaria. These data have led to a working hypothesis that PfEMP1 variants associated with parasite virulence are relatively conserved in structure. However, the longevity of such serologically conserved variants in the parasite population is unknown. Here, using infected erythrocytes from recently sampled clinical P. falciparum samples, we measured serological conservation using pools of antibodies in sera that had been sampled 10 to 12 years earlier. The serological conservation of infected erythrocytes strongly correlated with the expression of specific PfEMP1 subsets previously found to be associated with severe malaria. However, we found no association between serological conservation per se and disease severity within these data. This contrasts with the simple hypothesis that P. falciparum isolates with a serologically conserved group of PfEMP1 variants cause severe malaria. The data are instead consistent with periodic turnover of the immunodominant epitopes of PfEMP1 associated with severe malaria.

  5. Antibodies that protect humans against Plasmodium falciparum blood stages do not on their own inhibit parasite growth and invasion in vitro, but act in cooperation with monocytes

    PubMed Central

    1990-01-01

    IgG extracted from the sera of African adults immune to malaria were injected intravenously into eight Plasmodium falciparum-infected nonimmune Thai patients. Clinical and parasitological improvement was reproducibly obtained in each case. After the disappearance of the transferred Ig, recrudescent parasites were equally susceptible to the same Ig preparation. High levels of antibodies to most parasite proteins were detected by Western blots in the receivers' sera (taken before transfer) as in the donors' Ig, thus indicating that the difference was qualitative rather than quantitative between donors and receivers. In vitro, the clinically effective Ig had no detectable inhibitory effect on either penetration or intra-erythrocytic development of the parasite. On the contrary, they sometimes increased parasite growth. In contrast, these IgG, as the receivers' Ig collected 4 d after transfer, but not those collected before transfer, proved able to exert an antibody-dependent cellular inhibitory (ADCI) effect in cooperation with normal blood monocytes. Results were consistent among the seven isolates studied in vitro, as with the recrudescent parasites. Thus, the results obtained in the ADCI assay correlate closely with clinical and parasitological observations. PMID:2258697

  6. Relative Undernourishment and Food Insecurity Associations with Plasmodium falciparum Among Batwa Pygmies in Uganda: Evidence from a Cross-Sectional Survey

    PubMed Central

    Lewnard, Joseph A.; Berrang-Ford, Lea; Lwasa, Shuaib; Namanya, Didacus Bambaiha; Patterson, Kaitlin A.; Donnelly, Blánaid; Kulkarni, Manisha A.; Harper, Sherilee L.; Ogden, Nicholas H.; Carcamo, Cesar P.

    2014-01-01

    Although malnutrition and malaria co-occur among individuals and populations globally, effects of nutritional status on risk for parasitemia and clinical illness remain poorly understood. We investigated associations between Plasmodium falciparum infection, nutrition, and food security in a cross-sectional survey of 365 Batwa pygmies in Kanungu District, Uganda in January of 2013. We identified 4.1% parasite prevalence among individuals over 5 years old. Severe food insecurity was associated with increased risk for positive rapid immunochromatographic test outcome (adjusted relative risk [ARR] = 13.09; 95% confidence interval [95% CI] = 2.23–76.79). High age/sex-adjusted mid-upper arm circumference was associated with decreased risk for positive test among individuals who were not severely food-insecure (ARR = 0.37; 95% CI = 0.19–0.69). Within Batwa pygmy communities, where malnutrition and food insecurity are common, individuals who are particularly undernourished or severely food-insecure may have elevated risk for P. falciparum parasitemia. This finding may motivate integrated control of malaria and malnutrition in low-transmission settings. PMID:24821844

  7. Placental Sequestration of Plasmodium falciparum Malaria Parasites Is Mediated by the Interaction Between VAR2CSA and Chondroitin Sulfate A on Syndecan-1.

    PubMed

    Ayres Pereira, Marina; Mandel Clausen, Thomas; Pehrson, Caroline; Mao, Yang; Resende, Mafalda; Daugaard, Mads; Riis Kristensen, Anders; Spliid, Charlotte; Mathiesen, Line; E Knudsen, Lisbeth; Damm, Peter; G Theander, Thor; R Hansson, Stefan; A Nielsen, Morten; Salanti, Ali

    2016-08-01

    During placental malaria, Plasmodium falciparum infected erythrocytes sequester in the placenta, causing health problems for both the mother and fetus. The specific adherence is mediated by the VAR2CSA protein, which binds to placental chondroitin sulfate (CS) on chondroitin sulfate proteoglycans (CSPGs) in the placental syncytium. However, the identity of the CSPG core protein and the cellular impact of the interaction have remain elusive. In this study we identified the specific CSPG core protein to which the CS is attached, and characterized its exact placental location. VAR2CSA pull-down experiments using placental extracts from whole placenta or syncytiotrophoblast microvillous cell membranes showed three distinct CSPGs available for VAR2CSA adherence. Further examination of these three CSPGs by immunofluorescence and proximity ligation assays showed that syndecan-1 is the main receptor for VAR2CSA mediated placental adherence. We further show that the commonly used placental choriocarcinoma cell line, BeWo, express a different set of proteoglycans than those present on placental syncytiotrophoblast and may not be the most biologically relevant model to study placental malaria. Syncytial fusion of the BeWo cells, triggered by forskolin treatment, caused an increased expression of placental CS-modified syndecan-1. In line with this, we show that rVAR2 binding to placental CS impairs syndecan-1-related Src signaling in forskolin treated BeWo cells, but not in untreated cells. PMID:27556547

  8. Placental Sequestration of Plasmodium falciparum Malaria Parasites Is Mediated by the Interaction Between VAR2CSA and Chondroitin Sulfate A on Syndecan-1

    PubMed Central

    Mao, Yang; Resende, Mafalda; Daugaard, Mads; Riis Kristensen, Anders; Damm, Peter; G. Theander, Thor; R. Hansson, Stefan; Salanti, Ali

    2016-01-01

    During placental malaria, Plasmodium falciparum infected erythrocytes sequester in the placenta, causing health problems for both the mother and fetus. The specific adherence is mediated by the VAR2CSA protein, which binds to placental chondroitin sulfate (CS) on chondroitin sulfate proteoglycans (CSPGs) in the placental syncytium. However, the identity of the CSPG core protein and the cellular impact of the interaction have remain elusive. In this study we identified the specific CSPG core protein to which the CS is attached, and characterized its exact placental location. VAR2CSA pull-down experiments using placental extracts from whole placenta or syncytiotrophoblast microvillous cell membranes showed three distinct CSPGs available for VAR2CSA adherence. Further examination of these three CSPGs by immunofluorescence and proximity ligation assays showed that syndecan-1 is the main receptor for VAR2CSA mediated placental adherence. We further show that the commonly used placental choriocarcinoma cell line, BeWo, express a different set of proteoglycans than those present on placental syncytiotrophoblast and may not be the most biologically relevant model to study placental malaria. Syncytial fusion of the BeWo cells, triggered by forskolin treatment, caused an increased expression of placental CS-modified syndecan-1. In line with this, we show that rVAR2 binding to placental CS impairs syndecan-1-related Src signaling in forskolin treated BeWo cells, but not in untreated cells. PMID:27556547

  9. Relative undernourishment and food insecurity associations with Plasmodium falciparum among Batwa pygmies in Uganda: evidence from a cross-sectional survey.

    PubMed

    Lewnard, Joseph A; Berrang-Ford, Lea; Lwasa, Shuaib; Namanya, Didacus Bambaiha; Patterson, Kaitlin A; Donnelly, Blánaid; Kulkarni, Manisha A; Harper, Sherilee L; Ogden, Nicholas H; Carcamo, Cesar P

    2014-07-01

    Although malnutrition and malaria co-occur among individuals and populations globally, effects of nutritional status on risk for parasitemia and clinical illness remain poorly understood. We investigated associations between Plasmodium falciparum infection, nutrition, and food security in a cross-sectional survey of 365 Batwa pygmies in Kanungu District, Uganda in January of 2013. We identified 4.1% parasite prevalence among individuals over 5 years old. Severe food insecurity was associated with increased risk for positive rapid immunochromatographic test outcome (adjusted relative risk [ARR] = 13.09; 95% confidence interval [95% CI] = 2.23-76.79). High age/sex-adjusted mid-upper arm circumference was associated with decreased risk for positive test among individuals who were not severely food-insecure (ARR = 0.37; 95% CI = 0.19-0.69). Within Batwa pygmy communities, where malnutrition and food insecurity are common, individuals who are particularly undernourished or severely food-insecure may have elevated risk for P. falciparum parasitemia. This finding may motivate integrated control of malaria and malnutrition in low-transmission settings. PMID:24821844

  10. Evidence of an increased incidence of day 3 parasitaemia in Suriname: an indicator of the emerging resistance of Plasmodium falciparum to artemether

    PubMed Central

    Vreden, Stephen GS; Jitan, Jeetendra K; Bansie, Rakesh D; Adhin, Malti R

    2013-01-01

    The emerging resistance to artemisinin derivatives that has been reported in South-East Asia led us to assess the efficacy of artemether-lumefantrine as the first line therapy for uncomplicated Plasmodium falciparum infections in Suriname. This drug assessment was performed according to the recommendations of the World Health Organization in 2011. The decreasing number of malaria cases in Suriname, which are currently limited to migrating populations and gold miners, precludes any conclusions on artemether efficacy because adequate numbers of patients with 28-day follow-up data are difficult to obtain. Therefore, a comparison of day 3 parasitaemia in a 2011 study and in a 2005/2006 study was used to detect the emergence of resistance to artemether. The prevalence of day 3 parasitaemia was assessed in a study in 2011 and was compared to that in a study in 2005/2006. The same protocol was used in both studies and artemether-lumefantrine was the study drug. Of 48 evaluable patients in 2011, 15 (31%) still had parasitaemia on day 3 compared to one (2%) out of 45 evaluable patients in 2005/2006. Overall, 11 evaluable patients in the 2011 study who were followed up until day 28 had negative slides and similar findings were obtained in all 38 evaluable patients in the 2005/2006 study. The significantly increased incidence of parasite persistence on day 3 may be an indication of emerging resistance to artemether. PMID:24402149

  11. Wolbachia increases susceptibility to Plasmodium infection in a natural system

    PubMed Central

    Zélé, F.; Nicot, A.; Berthomieu, A.; Weill, M.; Duron, O.; Rivero, A.

    2014-01-01

    Current views about the impact of Wolbachia on Plasmodium infections are almost entirely based on data regarding artificially transfected mosquitoes. This work has shown that Wolbachia reduces the intensity of Plasmodium infections in mosquitoes, raising the exciting possibility of using Wolbachia to control or limit the spread of malaria. Whether natural Wolbachia infections have the same parasite-inhibiting properties is not yet clear. Wolbachia–mosquito combinations with a long evolutionary history are, however, key for understanding what may happen with Wolbachia-transfected mosquitoes after several generations of coevolution. We investigate this issue using an entirely natural mosquito–Wolbachia–Plasmodium combination. In contrast to most previous studies, which have been centred on the quantification of the midgut stages of Plasmodium, we obtain a measurement of parasitaemia that relates directly to transmission by following infections to the salivary gland stages. We show that Wolbachia increases the susceptibility of Culex pipiens mosquitoes to Plasmodium relictum, significantly increasing the prevalence of salivary gland stage infections. This effect is independent of the density of Wolbachia in the mosquito. These results suggest that naturally Wolbachia-infected mosquitoes may, in fact, be better vectors of malaria than Wolbachia-free ones. PMID:24500167

  12. Backward bifurcation and optimal control of Plasmodium Knowlesi malaria

    NASA Astrophysics Data System (ADS)

    Abdullahi, Mohammed Baba; Hasan, Yahya Abu; Abdullah, Farah Aini

    2014-07-01

    A deterministic model for the transmission dynamics of Plasmodium Knowlesi malaria with direct transmission is developed. The model is analyzed using dynamical system techniques and it shows that the backward bifurcation occurs for some range of parameters. The model is extended to assess the impact of time dependent preventive (biological and chemical control) against the mosquitoes and vaccination for susceptible humans, while treatment for infected humans. The existence of optimal control is established analytically by the use of optimal control theory. Numerical simulations of the problem, suggest that applying the four control measure can effectively reduce if not eliminate the spread of Plasmodium Knowlesi in a community.

  13. High prevalence of sulphadoxine-pyrimethamine resistance-associated mutations in Plasmodium falciparum field isolates from pregnant women in Brazzaville, Republic of Congo.

    PubMed

    Koukouikila-Koussounda, Felix; Bakoua, Damien; Fesser, Anna; Nkombo, Michael; Vouvoungui, Christevy; Ntoumi, Francine

    2015-07-01

    Intermittent preventive treatment during pregnancy with sulfadoxine-pyrimethamine (IPTp-SP) has not been evaluated in the Republic of Congo since its implementation in 2006 and there is no published data on molecular markers of SP resistance among Plasmodium falciparum isolates from pregnant women. This first study in this country aimed to describe the prevalence of dihydrofolate reductase (dhfr) and dihydropteroate synthase (dhps) point mutations and haplotypes in P. falciparum isolates collected from pregnant women with asymptomatic infection. From March 2012 to December 2013, pregnant women attending Madibou health centre (in Southern Brazzaville) for antenatal visits were enrolled in this study after obtaining their written informed consent. Blood samples were collected and P. falciparum infections were characterized using PCR. A total of 363 pregnant women were enrolled. P. falciparum infection was detected in 67 (18.4%) samples as their PCR amplification of dhfr and dhps genes yielded bands and all the PCR products were successfully digested. Out of these 67 isolates, 59 (88%), 57 (85%) and 53 (79.1%) carried 51I, 59R and 108N dhfr mutant alleles, respectively. The prevalence of dhps 436A, 437G and 540E mutations were 67.1% (45/67), 98.5% (66/67) and 55.2% (37/67), respectively. More than one-half of the isolates carried quintuple mutations, with highly resistant haplotype dhfr51I/59R/108N + dhps437G/540E detected in 33% (22/67) whereas 25% (17/67) were found to carry sextuple mutations. We observed significantly higher frequencies of triple dhps mutations 436A/437G/540E and quintuple mutations dhfr51I/59R/108N+dhps437G/540E in isolates from women who received IPTp-SP than those who did not. Overall, this study shows high prevalence rates of SP-associated resistance mutations in P. falciparum isolates collected from pregnant women. The presence of the dhps mutant allele 540E and the high prevalence of isolates carrying quintuple dhfr/dhps mutations are here

  14. Microscopic Plasmodium falciparum Gametocytemia and Infectivity to Mosquitoes in Cambodia.

    PubMed

    Lin, Jessica T; Ubalee, Ratawan; Lon, Chanthap; Balasubramanian, Sujata; Kuntawunginn, Worachet; Rahman, Rifat; Saingam, Piyaporn; Heng, Thay Kheang; Vy, Dav; San, Savoeun; Nuom, Sarath; Burkly, Hana; Chanarat, Nitima; Ponsa, Chanudom; Levitz, Lauren; Parobek, Christian; Chuor, Char Meng; Somethy, Sok; Spring, Michele; Lanteri, Charlotte; Gosi, Panita; Meshnick, Steven R; Saunders, David L

    2016-05-01

    Although gametocytes are essential for malaria transmission, in Africa many falciparum-infected persons without smear-detectable gametocytes still infect mosquitoes. To see whether the same is true in Southeast Asia, we determined the infectiousness of 119 falciparum-infected Cambodian adults to Anopheles dirus mosquitoes by membrane feeding. Just 5.9% of subjects infected mosquitoes. The 8.4% of patients with smear-detectable gametocytes were >20 times more likely to infect mosquitoes than those without and were the source of 96% of all mosquito infections. In low-transmission settings, targeting transmission-blocking interventions to those with microscopic gametocytemia may have an outsized effect on malaria control and elimination.

  15. Transcription and Expression of Plasmodium falciparum Histidine-Rich Proteins in Different Stages and Strains: Implications for Rapid Diagnostic Tests

    PubMed Central

    Baker, Joanne; Gatton, Michelle L.; Peters, Jennifer; Ho, Mei-Fong; McCarthy, James S.; Cheng, Qin

    2011-01-01

    Background Although rapid diagnostic tests (RDTs) for Plasmodium falciparum infection that target histidine rich protein 2 (PfHRP2) are generally sensitive, their performance has been reported to be variable. One possible explanation for variable test performance is differences in expression level of PfHRP in different parasite isolates. Methods Total RNA and protein were extracted from synchronised cultures of 7 P. falciparum lines over 5 time points of the life cycle, and from synchronised ring stages of 10 falciparum lines. Using quantitative real-time polymerase chain reaction, Western blot analysis and ELISA we investigated variations in the transcription and protein levels of pfhrp2, pfhrp3 and PfHRP respectively in the different parasite lines, over the parasite intraerythrocytic life cycle. Results Transcription of pfhrp2 and pfhrp3 in different parasite lines over the parasite life cycle was observed to vary relative to the control parasite K1. In some parasite lines very low transcription of these genes was observed. The peak transcription was observed in ring-stage parasites. Pfhrp2 transcription was observed to be consistently higher than pfhrp3 transcription within parasite lines. The intraerythrocytic lifecycle stage at which the peak level of protein was present varied across strains. Total protein levels were more constant relative to total mRNA transcription, however a maximum 24 fold difference in expression at ring-stage parasites relative to the K1 strain was observed. Conclusions The levels of transcription of pfhrp2 and pfhrp3, and protein expression of PfHRP varied between different P. falciparum strains. This variation may impact on the detection sensitivity of PfHRP2-detecting RDTs. PMID:21799910

  16. Importation of chloroquine-resistant Plasmodium falciparum by Guatemalan peacekeepers returning from the Democratic Republic of the Congo

    PubMed Central

    2013-01-01

    Background Malaria elimination is being pursued in five of seven Central American countries. Military personnel returning from peacekeeping missions in sub-Saharan Africa could import chloroquine-resistant Plasmodium falciparum, posing a threat to elimination and to the continued efficacy of first-line chloroquine (CQ) treatment in these countries. This report describes the importation of P. falciparum from among 150 Guatemalan army special forces and support staff who spent ten months on a United Nations’ peacekeeping mission in the Democratic Republic of the Congo (DRC) in 2010. Methods Investigators reviewed patients’ medical charts and interviewed members of the contingent to identify malaria cases and risk factors for malaria acquisition. Clinical specimens were tested for malaria; isolated parasites were characterized molecularly for CQ resistance. Results Investigators identified 12 cases (8%) of laboratory-confirmed P. falciparum infection within the contingent; one case was from a soldier infected with a CQ-resistant pfcrt genotype resulting in his death. None of the contingent used an insecticide-treated bed net (ITN) or completely adhered to malaria chemoprophylaxis while in the DRC. Conclusion This report highlights the need to promote use of malaria prevention measures, in particular ITNs and chemoprophylaxis, among peacekeepers stationed in malaria-endemic areas. Countries attempting to eliminate malaria should consider appropriate methods to screen peacekeepers returning from endemic areas for malaria infections. Cases of malaria in travellers, immigrants and soldiers returning to Central America from countries with CQ-resistant malaria should be assumed to be carry resistant parasites and receive appropriate anti-malarial therapy to prevent severe disease and death. PMID:24060234

  17. Spread of artemisinin-resistant Plasmodium falciparum in Myanmar: a cross-sectional survey of the K13 molecular marker

    PubMed Central

    Tun, Kyaw M; Imwong, Mallika; Lwin, Khin M; Win, Aye A; Hlaing, Tin M; Hlaing, Thaung; Lin, Khin; Kyaw, Myat P; Plewes, Katherine; Faiz, M Abul; Dhorda, Mehul; Cheah, Phaik Yeong; Pukrittayakamee, Sasithon; Ashley, Elizabeth A; Anderson, Tim J C; Nair, Shalini; McDew-White, Marina; Flegg, Jennifer A; Grist, Eric P M; Guerin, Philippe; Maude, Richard J; Smithuis, Frank; Dondorp, Arjen M; Day, Nicholas P J; Nosten, François; White, Nicholas J; Woodrow, Charles J

    2015-01-01

    Summary Background Emergence of artemisinin resistance in southeast Asia poses a serious threat to the global control of Plasmodium falciparum malaria. Discovery of the K13 marker has transformed approaches to the monitoring of artemisinin resistance, allowing introduction of molecular surveillance in remote areas through analysis of DNA. We aimed to assess the spread of artemisinin-resistant P falciparum in Myanmar by determining the relative prevalence of P falciparum parasites carrying K13-propeller mutations. Methods We did this cross-sectional survey at malaria treatment centres at 55 sites in ten administrative regions in Myanmar, and in relevant border regions in Thailand and Bangladesh, between January, 2013, and September, 2014. K13 sequences from P falciparum infections were obtained mainly by passive case detection. We entered data into two geostatistical models to produce predictive maps of the estimated prevalence of mutations of the K13 propeller region across Myanmar. Findings Overall, 371 (39%) of 940 samples carried a K13-propeller mutation. We recorded 26 different mutations, including nine mutations not described previously in southeast Asia. In seven (70%) of the ten administrative regions of Myanmar, the combined K13-mutation prevalence was more than 20%. Geospatial mapping showed that the overall prevalence of K13 mutations exceeded 10% in much of the east and north of the country. In Homalin, Sagaing Region, 25 km from the Indian border, 21 (47%) of 45 parasite samples carried K13-propeller mutations. Interpretation Artemisinin resistance extends across much of Myanmar. We recorded P falciparum parasites carrying K13-propeller mutations at high prevalence next to the northwestern border with India. Appropriate therapeutic regimens should be tested urgently and implemented comprehensively if spread of artemisinin resistance to other regions is to be avoided. Funding Wellcome Trust–Mahidol University–Oxford Tropical Medicine Research

  18. Plasmodium vivax malaria during pregnancy, Bolivia.

    PubMed

    Brutus, Laurent; Santalla, José; Schneider, Dominique; Avila, Juan Carlos; Deloron, Philippe

    2013-10-01

    Plasmodium vivax is a major cause of illness in areas with low transmission of malaria in Latin America, Asia, and the Horn of Africa. However, pregnancy-associated malaria remains poorly characterized in such areas. Using a hospital-based survey of women giving birth and an antenatal survey, we assessed the prevalence rates of Plasmodium spp. infections in pregnant women in Bolivia, and evaluated the consequences of malaria during pregnancy on the health of mothers and newborns. P. vivax infection was detected in 7.9% of pregnant women attending antenatal visits, and placental infection occurred in 2.8% of deliveries; these rates did not vary with parity. Forty-two percent of all P. vivax malaria episodes were symptomatic. P. vivax-infected pregnant women were frequently anemic (6.5%) and delivered babies of reduced birthweight. P. vivax infections during pregnancy are clearly associated with serious adverse outcomes and should be considered in prevention strategies of pregnancy-associated malaria.

  19. Rapid diagnostic tests for diagnosing uncomplicated non-falciparum or Plasmodium vivax malaria in endemic countries

    PubMed Central

    Abba, Katharine; Kirkham, Amanda J; Olliaro, Piero L; Deeks, Jonathan J; Donegan, Sarah; Garner, Paul; Takwoingi, Yemisi

    2014-01-01

    Background In settings where both Plasmodium vivax and Plasmodium falciparum infection cause malaria, rapid diagnostic tests (RDTs) need to distinguish which species is causing the patients' symptoms, as different treatments are required. Older RDTs incorporated two test lines to distinguish malaria due to P. falciparum, from malaria due to any other Plasmodium species (non-falciparum). These RDTs can be classified according to which antibodies they use: Type 2 RDTs use HRP-2 (for P. falciparum) and aldolase (all species); Type 3 RDTs use HRP-2 (for P. falciparum) and pLDH (all species); Type 4 use pLDH (fromP. falciparum) and pLDH (all species). More recently, RDTs have been developed to distinguish P. vivax parasitaemia by utilizing a pLDH antibody specific to P. vivax. Objectives To assess the diagnostic accuracy of RDTs for detecting non-falciparum or P. vivax parasitaemia in people living in malaria-endemic areas who present to ambulatory healthcare facilities with symptoms suggestive of malaria, and to identify which types and brands of commercial test best detect non-falciparum and P. vivax malaria. Search methods We undertook a comprehensive search of the following databases up to 31 December 2013: Cochrane Infectious Diseases Group Specialized Register; MEDLINE; EMBASE; MEDION; Science Citation Index; Web of Knowledge; African Index Medicus; LILACS; and IndMED. Selection criteria Studies comparing RDTs with a reference standard (microscopy or polymerase chain reaction) in blood samples from a random or consecutive series of patients attending ambulatory health facilities with symptoms suggestive of malaria in non-falciparum endemic areas. Data collection and analysis For each study, two review authors independently extracted a standard set of data using a tailored data extraction form. We grouped comparisons by type of RDT (defined by the combinations of antibodies used), and combined in meta-analysis where appropriate. Average sensitivities and

  20. Epidemiology of Disappearing Plasmodium vivax Malaria: A Case Study in Rural Amazonia

    PubMed Central

    Lima, Nathália F.; Batista, Camilla L.; Bastos, Melissa da Silva; Nicolete, Vanessa C.; Fontoura, Pablo S.; Gonçalves, Raquel M.; Viana, Susana Ariane S.; Menezes, Maria José; Scopel, Kézia Katiani G.; Cavasini, Carlos E.; Malafronte, Rosely dos Santos; da Silva-Nunes, Mônica; Vinetz, Joseph M.; Castro, Márcia C.; Ferreira, Marcelo U.

    2014-01-01

    Background New frontier settlements across the Amazon Basin pose a major challenge for malaria elimination in Brazil. Here we describe the epidemiology of malaria during the early phases of occupation of farming settlements in Remansinho area, Brazilian Amazonia. We examine the relative contribution of low-density and asymptomatic parasitemias to the overall Plasmodium vivax burden over a period of declining transmission and discuss potential hurdles for malaria elimination in Remansinho and similar settings. Methods Eight community-wide cross-sectional surveys, involving 584 subjects, were carried out in Remansinho over 3 years and complemented by active and passive surveillance of febrile illnesses between the surveys. We used quantitative PCR to detect low-density asexual parasitemias and gametocytemias missed by conventional microscopy. Mixed-effects multiple logistic regression models were used to characterize independent risk factors for P. vivax infection and disease. Principal Findings/Conclusions P. vivax prevalence decreased from 23.8% (March–April 2010) to 3.0% (April–May 2013), with no P. falciparum infections diagnosed after March–April 2011. Although migrants from malaria-free areas were at increased risk of malaria, their odds of having P. vivax infection and disease decreased by 2–3% with each year of residence in Amazonia. Several findings indicate that low-density and asymptomatic P. vivax parasitemias may complicate residual malaria elimination in Remansinho: (a) the proportion of subpatent infections (i.e. missed by microscopy) increased from 43.8% to 73.1% as P. vivax transmission declined; (b) most (56.6%) P. vivax infections were asymptomatic and 32.8% of them were both subpatent and asymptomatic; (c) asymptomatic parasite carriers accounted for 54.4% of the total P. vivax biomass in the host population; (d) over 90% subpatent and asymptomatic P. vivax had PCR-detectable gametocytemias; and (e) few (17.0%) asymptomatic and subpatent P

  1. Proteasome Inhibitors Block Development of Plasmodium spp.

    PubMed Central

    Gantt, Soren M.; Myung, Joon Mo; Briones, Marcelo R. S.; Li, Wei Dong; Corey, E. J.; Omura, Satoshi; Nussenzweig, Victor; Sinnis, Photini

    1998-01-01

    Proteasomes degrade most of the proteins inside eukaryotic cells, including transcription factors and regulators of cell cycle progression. Here we show that nanomolar concentrations of lactacystin, a specific irreversible inhibitor of the 20S proteasome, inhibit development of the exoerythrocytic and erythrocytic stages of the malaria parasite. Although lactacystin-treated Plasmodium berghei sporozoites are still invasive, their development into exoerythrocytic forms (EEF) is inhibited in vitro and in vivo. Erythrocytic schizogony of P. falciparum in vitro is also profoundly inhibited when drug treatment of the synchronized parasites is prior, but not subsequent, to the initiation of DNA synthesis, suggesting that the inhibitory effect of lactacystin is cell cycle specific. Lactacystin reduces P. berghei parasitemia in rats, but the therapeutic index is very low. Along with other studies showing that lactacystin inhibits stage-specific transformation in Trypanosoma and Entamoeba spp., these findings highlight the potential of proteasome inhibitors as drugs for the treatment of diseases caused by protozoan parasites. PMID:9756786

  2. Detection of Plasmodium sp. in capybara.

    PubMed

    dos Santos, Leonilda Correia; Curotto, Sandra Mara Rotter; de Moraes, Wanderlei; Cubas, Zalmir Silvino; Costa-Nascimento, Maria de Jesus; de Barros Filho, Ivan Roque; Biondo, Alexander Welker; Kirchgatter, Karin

    2009-07-01

    In the present study, we have microscopically and molecularly surveyed blood samples from 11 captive capybaras (Hydrochaeris hydrochaeris) from the Sanctuary Zoo for Plasmodium sp. infection. One animal presented positive on blood smear by light microscopy. Polymerase chain reaction was carried out accordingly using a nested genus-specific protocol, which uses oligonucleotides from conserved sequences flanking a variable sequence region in the small subunit ribosomal RNA (ssrRNA) of all Plasmodium organisms. This revealed three positive animals. Products from two samples were purified and sequenced. The results showed less than 1% divergence between the two capybara sequences. When compared with GenBank sequences, a 55% similarity was obtained to Toxoplasma gondii and a higher similarity (73-77.2%) was found to ssrRNAs from Plasmodium species that infect reptile, avian, rodents, and human beings. The most similar Plasmodium sequence was from Plasmodium mexicanum that infects lizards of North America, where around 78% identity was found. This work is the first report of Plasmodium in capybaras, and due to the low similarity with other Plasmodium species, we suggest it is a new species, which, in the future could be denominated "Plasmodium hydrochaeri".

  3. Genetic Resistance to Malaria Is Associated With Greater Enhancement of Immunoglobulin (Ig)M Than IgG Responses to a Broad Array of Plasmodium falciparum Antigens

    PubMed Central

    Arama, Charles; Skinner, Jeff; Doumtabe, Didier; Portugal, Silvia; Tran, Tuan M.; Jain, Aarti; Traore, Boubacar; Doumbo, Ogobara K.; Davies, David Huw; Troye-Blomberg, Marita; Dolo, Amagana; Felgner, Philip L.; Crompton, Peter D.

    2015-01-01

    Background. People of the Fulani ethnic group are more resistant to malaria compared with genetically distinct ethnic groups, such as the Dogon people, in West Africa, and studies suggest that this resistance is mediated by enhanced antibody responses to Plasmodium falciparum antigens. However, prior studies measured antibody responses to <0.1% of P falciparum proteins, so whether the Fulani mount an enhanced and broadly reactive immunoglobulin (Ig)M and IgG response to P falciparum remains unknown. In general, little is known about the extent to which host genetics influence the overall antigen specificity of IgM and IgG responses to natural infections. Methods. In a cross-sectional study in Mali, we collected plasma from asymptomatic, age-matched Fulani (n = 24) and Dogon (n = 22) adults with or without concurrent P falciparum infection. We probed plasma against a protein microarray containing 1087 P falciparum antigens and compared IgM and IgG profiles by ethnicity. Results. We found that the breadth and magnitude of P falciparum-specific IgM and IgG responses were significantly higher in the malaria-resistant Fulani versus the malaria-susceptible Dogon, and, unexpectedly, P falciparum-specific IgM responses more strongly distinguished the 2 ethnic groups. Conclusions. These findings point to an underappreciated role for IgM in protection from malaria, and they suggest that host genetics may influence the antigen specificity of IgM and IgG responses to infection. PMID:26361633

  4. Detection of the Plasmodium falciparum antigen histidine-rich protein 2 in blood of pregnant women: implications for diagnosing placental malaria.

    PubMed

    Leke, R F; Djokam, R R; Mbu, R; Leke, R J; Fogako, J; Megnekou, R; Metenou, S; Sama, G; Zhou, Y; Cadigan, T; Parra, M; Taylor, D W

    1999-09-01

    Pregnant women have an increased susceptibility to infection by Plasmodium falciparum. Parasites may be present in the placenta yet not detectable in peripheral blood smears by routine light microscopy. In order to determine how frequently misdiagnosis occurs, peripheral blood and placental samples were collected from 1,077 Cameroonian women at the time of giving birth and examined for the presence of malarial parasites by using light microscopy. Results showed that 20.1% of the women who had placental malaria were peripheral blood smear negative. Thus, malarial infection was not detected by microscopic examination of peripheral blood smears from approximately one out of five malaria-infected women. Since P. falciparum parasites secrete histidine-rich protein 2 (HRP-2), we sought to determine if detecting HRP-2 in either peripheral plasma or whole blood might be used to diagnose the presence of parasites "hidden" in the placenta. Samples of peripheral plasma from 127 women with different levels of placental malarial infection were assayed by HRP-2-specific enzyme-linked immunosorbent assay. HRP-2 was detected in 88% of the women with placental malaria who tested negative by blood smear. Additionally, whole blood was obtained from 181 women and tested for HRP-2 with a rapid, chromatographic strip test (ICT). The ICT test accurately detected malarial infection in 89.1% of P. falciparum-infected women. Furthermore, 94% of women with malaria were accurately diagnosed by using a combination of microscopy and the ICT test. Thus, detection of HRP-2 in conjunction with microscopy should improve diagnosis of malaria in pregnant women.

  5. Double mutation in the pfmdr1 gene is associated with emergence of chloroquine-resistant Plasmodium falciparum malaria in Eastern India.

    PubMed

    Das, Sabyasachi; Mahapatra, Santanu Kar; Tripathy, Satyajit; Chattopadhyay, Sourav; Dash, Sandeep Kumar; Mandal, Debasis; Das, Balaram; Hati, Amiya Kumar; Roy, Somenath

    2014-10-01

    Malaria is a major public health problem in tropical and subtropical countries, including India. This study elucidates the cause of chloroquine treatment failure (for Plasmodium falciparum infection) before the introduction of artemisinin combination therapy. One hundred twenty-six patients were randomized to chloroquine treatment, and the therapeutic efficacy was monitored from days 1 to 28. An in vitro susceptibility test was performed with all isolates. Parasitic DNA was isolated, followed by PCR and restriction digestion of different codons of the pfcrt gene (codons 72 to 76) and the pfmdr1 gene (N86Y, Y184F, S1034C, N1042D, and D1246Y). Finally, sequencing was done to confirm the mutations. Forty-three (34.13%) early treatment failure cases and 16 (12.69%) late treatment failure cases were observed after chloroquine treatment. In vitro chloroquine resistance was found in 103 isolates (81.75%). Twenty-six (60.47%) early treatment failure cases and 6 (37.5%) late treatment failure cases were associated with the CVMNK-YYSNY allele (the underlined amino acids are those that were mutated). Moreover, the CVIEK-YYSNY allele was found in 8 early treatment failure (18.60%) and 2 late treatment failure (12.5%) cases. The presence of the wild-type pfcrt (CVMNK) and pfmdr1 (YYSNY) double mutant allele in chloroquine-nonresponsive cases was quite uncommon. In vivo chloroquine treatment failure and in vitro chloroquine resistance were strongly correlated with the CVMNK-YYSNY and CVIEK-YYSNY haplotypes (P < 0.01).

  6. Sickle cell trait carriage: imbalanced distribution of IgG subclass antibodies reactive to Plasmodium falciparum family-specific MSP2 peptides in serum samples from Gabonese children.

    PubMed

    Ntoumi, Francine; Ekala, Marie-Thérése; Makuwa, Maria; Lekoulou, Faustin; Mercereau-Puijalon, Odile; Deloron, Philippe

    2002-10-21

    Several mechanisms have been proposed for explaining the protection of young children with hemoglobin AS from severe Plasmodium falciparum malaria. In a previous study carried out in Gabon, we have shown an association between hemoglobin AS carriage and a greater P. falciparum infection complexity. In the present study, we have investigated the presence and fine specificity of merozoite surface protein 2 (MSP2) reactive antibodies using different peptides covering conserved and polymorphic regions (Blocks 1-3) of P. falciparum MSP2 molecules. A cross-sectional study was conducted in the city of Bakoumba (Gabon), where malaria is hyperendemic with perennial P. falciparum transmission. Among the 641 children included, 135 were heterozygous for the sickle cell trait (HbAS). There was no significant difference in age distribution (mean age: 5 years, 0.5-11 years) and sex ratio in both hemoglobin groups (HbAA vs. HbAS). Blood group O was, however, associated with the sickle cell trait (P=0.02). P. falciparum isolates obtained from children with HbAS had a trend to higher infection complexity before the age of 5 years. Plasma samples were tested for the presence of antibodies to the different MSP2 peptides. Total IgG antibodies with a predominant reactivity against the FC27 type (the predominant P. falciparum MSP2 genotype) were found in serum samples from both groups. The profile of the IgG subclasses varied according to the hemoglobin phenotype. IgG3 and IgG2 were predominantly detected in plasma samples from HbAS children, whereas mainly IgG3 was found in children with HbAA. The role of the high multiclonal carriage associated with high family-specific antibodies reactive to MSP2 in HbAS children with asymptomatic P. falciparum parasitism is discussed.

  7. Polymorphisms in host genes encoding NOSII, C-reactive protein, and adhesion molecules thrombospondin and E-selectin are risk factors for Plasmodium falciparum malaria in India.

    PubMed

    Kanchan, K; Pati, S S; Mohanty, S; Mishra, S K; Sharma, S K; Awasthi, S; Venkatesh, V; Habib, S

    2015-10-01

    Cytoadherence of Plasmodium falciparum-infected red blood cells (RBCs) in host microvasculature and complex regulation of the immune response are important contributors to the clinical outcome of disease. We tested the association of 23 single nucleotide polymorphisms (SNPs) and a microsatellite repeat in adhesion molecule genes THBS1 and ESEL, and immune regulatory molecule genes NOSII, CRP, and MBL2 with falciparum malaria in populations residing in a malaria-endemic and a non-endemic region of India. The THBS1 haplotype CCCCA (rs1478604, rs7170682, rs2664141, rs12912082, rs3743125) was a risk factor in the endemic region (relative risk = 3.78) and an ESEL SNP (rs5368, His468Tyr) associated with cerebral malaria (CM) [CM vs. non-cerebral malaria (NCM), odds ratio (OR) = 2.23, p = 0.03]. In the non-endemic region, an ESEL 3'UTR SNP (rs5359) associated with enhanced risk of disease (OR = 3.62, p = 1 × 10(-4)) and the CT genotype of the CRP promoter SNP (C/T/A) strongly associated with protection (severe vs. control, OR = 0.29, p = 6 × 10(-5)). Long repeat alleles of the NOSII promoter microsatellite (CCTTT)n exhibited strong association with protection and the NOSII ATG haplotype (rs3729508, rs2297520, rs9282801) was strongly protective against severe malaria in both regions (endemic, severe vs. control, OR = 0.05, p = 0.0001; non-endemic, severe vs. control, OR = 0.3, p = 1 × 10(-5)). Our results suggest differential contribution of variants of the investigated genes in determining the outcome of malaria in Indian populations.

  8. Proteomic analysis of Plasmodium falciparum induced alterations in humans from different endemic regions of India to decipher malaria pathogenesis and identify surrogate markers of severity.

    PubMed

    Ray, Sandipan; Kumar, Vipin; Bhave, Amruta; Singh, Vaidhvi; Gogtay, Nithya J; Thatte, Urmila M; Talukdar, Arunansu; Kochar, Sanjay K; Patankar, Swati; Srivastava, Sanjeeva

    2015-09-01

    India significantly contributes to the global malaria burden and has the largest population in the world at risk of malaria. This study aims to analyze alterations in the human serum proteome as a consequence of non-severe and severe infections by the malaria parasite Plasmodium falciparum to identify markers related to disease severity and to obtain mechanistic insights about disease pathogenesis and host immune responses. In discovery phase of the study, a comprehensive quantitative proteomic analysis was performed using gel-based (2D-DIGE) and gel-free (iTRAQ) techniques on two independent mass spectrometry platforms (ESI-Q-TOF and Q-Exactive mass spectrometry), and selected targets were validated by ELISA. Proteins showing altered serum abundance in falciparum malaria patients revealed the modulation of different physiological pathways including chemokine and cytokine signaling, IL-12 signaling and production in macrophages, complement cascades, blood coagulation, and protein ubiquitination pathways. Some muscle related and cytoskeletal proteins such as titin and galectin-3-binding protein were found to be up-regulated in severe malaria patients. Hemoglobin levels and platelet counts were also found to be drastically lower in severe malaria patients. Identified proteins including serum amyloid A, C-reactive protein, apolipoprotein E and haptoglobin, which exhibited sequential alterations in their serum abundance in different severity levels of malaria, could serve as potential predictive markers for disease severity. To the best of our information, we report here the first comprehensive analysis describing the serum proteomic alterations observed in severe P. falciparum infected patients from different malaria endemic regions of India. This article is part of a Special Issue entitled: Proteomics in India.

  9. A single point in protein trafficking by Plasmodium falciparum determines the expression of major antigens on the surface of infected erythrocytes targeted by human antibodies.

    PubMed

    Chan, Jo-Anne; Howell, Katherine B; Langer, Christine; Maier, Alexander G; Hasang, Wina; Rogerson, Stephen J; Petter, Michaela; Chesson, Joanne; Stanisic, Danielle I; Duffy, Michael F; Cooke, Brian M; Siba, Peter M; Mueller, Ivo; Bull, Peter C; Marsh, Kevin; Fowkes, Freya J I; Beeson, James G

    2016-11-01

    Antibodies to blood-stage antigens of Plasmodium falciparum play a pivotal role in human immunity to malaria. During parasite development, multiple proteins are trafficked from the intracellular parasite to the surface of P. falciparum-infected erythrocytes (IEs). However, the relative importance of different proteins as targets of acquired antibodies, and key pathways involved in trafficking major antigens remain to be clearly defined. We quantified antibodies to surface antigens among children, adults, and pregnant women from different malaria-exposed regions. We quantified the importance of antigens as antibody targets using genetically engineered P. falciparum with modified surface antigen expression. Genetic deletion of the trafficking protein skeleton-binding protein-1 (SBP1), which is involved in trafficking the surface antigen PfEMP1, led to a dramatic reduction in antibody recognition of IEs and the ability of human antibodies to promote opsonic phagocytosis of IEs, a key mechanism of parasite clearance. The great majority of antibody epitopes on the IE surface were SBP1-dependent. This was demonstrated using parasite isolates with different genetic or phenotypic backgrounds, and among antibodies from children, adults, and pregnant women in different populations. Comparisons of antibody reactivity to parasite isolates with SBP1 deletion or inhibited PfEMP1 expression suggest that PfEMP1 is the dominant target of acquired human antibodies, and that other P. falciparum IE surface proteins are minor targets. These results establish SBP1 as part of a critical pathway for the trafficking of major surface antigens targeted by human immunity, and have key implications for vaccine development, and quantifying immunity in populations.

  10. Efficacy and tolerability of artesunate plus sulfadoxine-pyrimethamine and sulfadoxine-pyrimethamine alone for the treatment of uncomplicated Plasmodium falciparum malaria in Peru.

    PubMed

    Marquiño, Wilmer; Ylquimiche, Laura; Hermenegildo, Ygor; Palacios, Ana Maria; Falconí, Eduardo; Cabezas, César; Arróspide, Nancy; Gutierrez, Sonia; Ruebush, Trenton K

    2005-05-01

    To assist the Peruvian Ministry of Health in modifying the malaria treatment policy for their north Pacific coastal region, we conducted an in vivo efficacy trial of sulfadoxine-pyrimethamine (SP) and SP plus artesunate (SP-AS) for the treatment for uncomplicated Plasmodium falciparum infections. A total of 197 patients were randomized to therapy with either SP (25 mg/kg of the sulfadoxine component in a single dose on day 0) or a combination of SP plus AS (4 mg/kg on days 0, 1, and 2) and were followed for 28 days for symptoms and recurrence of parasitemia. No statistically significant differences between the two groups were observed on enrollment with respect to age, sex, history of malaria, or geometric mean parasite density. A total of 185 subjects completed the 28-day follow-up. Of the 91 subjects treated with SP alone, two had recurrences of parasitemia on day 7 and one on day 21. Of the 94 subjects treated with SP-AS, one had a recurrence of parasitemia on day 21. Fever and asexual parasite density decreased significantly more rapidly and the proportion of patients with gametocytemia on days 3-28 was significantly lower in subjects treated with combination therapy than in those who received SP alone. No severe adverse drug reactions were observed; however, self-limited rash and pruritus were significantly more common and an exacerbation of nausea, vomiting, and abdominal pain were observed significantly more frequently among patients who had received SP-AS. These results have contributed to a National Malaria Control Program decision to change to SP-AS combination therapy as the first-line treatment for uncomplicated P. falciparum malaria in northern coastal Peru in November 2001, making Peru the first country in the Americas to recommend this combination therapy.

  11. Malaria immunoepidemiology in low transmission: correlation of infecting genotype and immune response to domains of Plasmodium falciparum merozoite surface protein 3.

    PubMed

    Jordan, Stephen J; Oliveira, Ana L; Hernandez, Jean N; Oster, Robert A; Chattopadhyay, Debasish; Branch, OraLee H; Rayner, Julian C

    2011-05-01

    Malaria caused by Plasmodium falciparum is a major cause of global infant mortality, and no effective vaccine currently exists. Multiple potential vaccine targets have been identified, and immunoepidemiology studies have played a major part in assessing those candidates. When such studies are carried out in high-transmission settings, individuals are often superinfected with complex mixtures of genetically distinct P. falciparum types, making it impossible to directly correlate the genotype of the infecting antigen with the antibody response. In contrast, in regions of low transmission P. falciparum infections are often genetically simple, and direct comparison of infecting genotype and antigen-specific immune responses is possible. As a test of the utility of this approach, responses against several domains and allelic variants of the vaccine candidate P. falciparum merozoite surface protein 3 (PfMSP3) were tested in serum samples collected near Iquitos, Peru. Antibodies recognizing both the conserved C-terminal and the more variable N-terminal domain were identified, but anti-N-terminal responses were more prevalent, of higher titers, and primarily of cytophilic subclasses. Comparing antibody responses to different PfMSP3 variants with the PfMSP3 genotype present at the time of infection showed that anti-N-terminal responses were largely allele class specific, but there was some evidence for responses that cross-reacted across allele classes. Evidence for cross-reactive responses was much stronger when variants within one allele class were tested, which has implications for the rational development of genotype-transcending PfMSP3-based vaccines.

  12. Effects of Age, Hemoglobin Type and Parasite Strain on IgG Recognition of Plasmodium falciparum–Infected Erythrocytes in Malian Children

    PubMed Central

    Zeituni, Amir E.; Miura, Kazutoyo; Diakite, Mahamadou; Doumbia, Saibou; Moretz, Samuel E.; Diouf, Ababacar; Tullo, Gregory; Lopera-Mesa, Tatiana M.; Bess, Cameron D.; Mita-Mendoza, Neida K.; Anderson, Jennifer M.; Fairhurst, Rick M.; Long, Carole A.

    2013-01-01

    Background Naturally-acquired antibody responses to antigens on the surface of Plasmodium falciparum-infected red blood cells (iRBCs) have been implicated in antimalarial immunity. To profile the development of this immunity, we have been studying a cohort of Malian children living in an area with intense seasonal malaria transmission. Methodology/Principal Findings We collected plasma from a sub-cohort of 176 Malian children aged 3-11 years, before (May) and after (December) the 2009 transmission season. To measure the effect of hemoglobin (Hb) type on antibody responses, we enrolled age-matched HbAA, HbAS and HbAC children. To quantify antibody recognition of iRBCs, we designed a high-throughput flow cytometry assay to rapidly test numerous plasma samples against multiple parasite strains. We evaluated antibody reactivity of each plasma sample to 3 laboratory-adapted parasite lines (FCR3, D10, PC26) and 4 short-term-cultured parasite isolates (2 Malian and 2 Cambodian). 97% of children recognized ≥1 parasite strain and the proportion of IgG responders increased significantly during the transmission season for most parasite strains. Both strain-specific and strain-transcending IgG responses were detected, and varied by age, Hb type and parasite strain. In addition, the breadth of IgG responses to parasite strains increased with age in HbAA, but not in HbAS or HbAC, children. Conclusions/Significance Our assay detects both strain-specific and strain-transcending IgG responses to iRBCs. The magnitude and breadth of these responses varied not only by age, but also by Hb type and parasite strain used. These findings indicate that studies of acquired humoral immunity should account for Hb type and test large numbers of diverse parasite strains. PMID:24124591

  13. Control of Plasmodium knowlesi malaria

    NASA Astrophysics Data System (ADS)

    Abdullahi, Mohammed Baba; Hasan, Yahya Abu; Abdullah, Farah Aini

    2015-10-01

    The most significant and efficient measures against Plasmodium knowlesi outbreaks are efficient anti malaria drug, biological control in form of predatory mosquitoes and culling control strategies. In this paper optimal control theory is applied to a system of ordinary differential equation. It describes the disease transmission and Pontryagin's Maximum Principle is applied for analysis of the control. To this end, three control strategies representing biological control, culling and treatment were incorporated into the disease transmission model. The simulation results show that the implementation of the combination strategy during the epidemic is the most cost-effective strategy for disease transmission.

  14. Targeting mosquito FREP1 with a fungal metabolite blocks malaria transmission

    PubMed Central

    Niu, Guodong; Wang, Bin; Zhang, Genwei; King, Jarrod B.; Cichewicz, Robert H.; Li, Jun

    2015-01-01

    Inhibiting Plasmodium development in mosquitoes will block malaria transmission. Fibrinogen-related protein 1 (FREP1) is critical for parasite infection in Anopheles gambiae and facilitates Plasmodium invasion in mosquitoes through interacting with gametocytes and ookinetes. To test the hypothesis that small molecules that disrupt this interaction will prevent parasites from infecting mosquitoes, we developed an ELISA-based method to screen a fungal extract library. We obtained a candidate fungal extract of Aspergillus niger that inhibited the interaction between FREP1 and P. falciparum infected cells by about 92%. The inhibition specificity was confirmed by immunofluorescence assays. Notably, feeding mosquitoes with the candidate fungal extract significantly inhibited P. falciparum infection in the midgut without cytotoxicity or inhibition of the development of P. falciparum gametocytes or ookinetes. A bioactive natural product that prevents FREP1 from binding to gametocytes or ookinetes was isolated and identified as P-orlandin. Importantly, the nontoxic orlandin significantly reduced P. falciparum infection intensity in mosquitoes. Therefore, disruption of the interaction between FREP1 and parasites effectively reduces Plasmodium infection in mosquitoes. Targeting FREP1 with small molecules is thus an effective novel approach to block malaria transmission. PMID:26437882

  15. Temperature alters Plasmodium blocking by Wolbachia

    NASA Astrophysics Data System (ADS)

    Murdock, Courtney C.; Blanford, Simon; Hughes, Grant L.; Rasgon, Jason L.; Thomas, Matthew B.

    2014-02-01

    Very recently, the Asian malaria vector (Anopheles stephensi) was stably transinfected with the wAlbB strain of Wolbachia, inducing refractoriness to the human malaria parasite Plasmodium falciparum. However, conditions in the field can differ substantially from those in the laboratory. We use the rodent malaria P. yoelii, and somatically transinfected An. stephensi as a model system to investigate whether the transmission blocking potential of wAlbB is likely to be robust across different thermal environments. wAlbB reduced malaria parasite prevalence and oocyst intensity at 28°C. At 24°C there was no effect on prevalence but a marked increase in oocyst intensity. At 20°C, wAlbB had no effect on prevalence or intensity. Additionally, we identified a novel effect of wAlbB that resulted in reduced sporozoite development across temperatures, counterbalancing the oocyst enhancement at 24°C. Our results demonstrate complex effects of temperature on the Wolbachia-malaria interaction, and suggest the impacts of transinfection might vary across diverse environments.

  16. Serological detection of Plasmodium vivax malaria using recombinant proteins corresponding to the 19-kDa C-terminal region of the merozoite surface protein-1

    PubMed Central

    Rodrigues, Maria Helena C; Cunha, Maristela G; Machado, Ricardo LD; Ferreira, Orlando C; Rodrigues, Mauricio M; Soares, Irene S

    2003-01-01

    Background Serological tests to detect antibodies specific to Plasmodium vivax could be a valuable tool for epidemiological studies, for screening blood donors in areas where the malaria is not endemic and for diagnosis of infected individuals. Because P. vivax cannot be easily obtained in vitro, ELISA assays using total or semi-purified antigens are rarely used. Based on this limitation, we tested whether recombinant proteins representing the 19 kDa C-terminal region of the merozoite surface protein-1 of P. vivax (MSP119) could be useful for serological detection of malaria infection. Methods Three purified recombinant proteins produced in Escherichia coli (GST-MSP119, His6-MSP119 and His6-MSP119-PADRE) and one in Pichia pastoris (yMSP119-PADRE) were compared for their ability to bind to IgG antibodies of individuals with patent P. vivax infection. The method was tested with 200 serum samples collected from individuals living in the north of Brazil in areas endemic for malaria, 53 serum samples from individuals exposed to Plasmodium falciparum infection and 177 serum samples from individuals never exposed to malaria. Results Overall, the sensitivity of the ELISA assessed with sera from naturally infected individuals was 95%. The proportion of serum samples that reacted with recombinant proteins GST-MSP119, His6-MSP119, His6-MSP119-PADRE and yMSP119-PADRE was 90%, 93.5%, 93.5% and 93.5%, respectively. The specificity values of the ELISA determined with sera from healthy individuals and from individuals with other infectious diseases were 98.3% (GST-MSP119), 97.7% (His6-MSP119 and His6-MSP119-PADRE) or 100% (yMSP119-PADRE). Conclusions Our study demonstrated that for the Brazilian population, an ELISA using a recombinant protein of the MSP119 can be used as the basis for the development of a valuable serological assay for the detection of P. vivax malaria. PMID:14617378

  17. Rapid diagnostic tests for diagnosing uncomplicated non-falciparum or Plasmodium vivax malaria in endemic countries

    PubMed Central

    Abba, Katharine; Kirkham, Amanda J; Olliaro, Piero L; Deeks, Jonathan J; Donegan, Sarah; Garner, Paul; Takwoingi, Yemisi

    2014-01-01

    Background In settings where both Plasmodium vivax and Plasmodium falciparum infection cause malaria, rapid diagnostic tests (RDTs) need to distinguish which species is causing the patients' symptoms, as different treatments are required. Older RDTs incorporated two test lines to distinguish malaria due to P. falciparum, from malaria due to any other Plasmodium species (non-falciparum). These RDTs can be classified according to which antibodies they use: Type 2 RDTs use HRP-2 (for P. falciparum) and aldolase (all species); Type 3 RDTs use HRP-2 (for P. falciparum) and pLDH (all species); Type 4 use pLDH (fromP. falciparum) and pLDH (all species). More recently, RDTs have been developed to distinguish P. vivax parasitaemia by utilizing a pLDH antibody specific to P. vivax. Objectives To assess the diagnostic accuracy of RDTs for detecting non-falciparum or P. vivax parasitaemia in people living in malaria-endemic areas who present to ambulatory healthcare facilities with symptoms suggestive of malaria, and to identify which types and brands of commercial test best detect non-falciparum and P. vivax malaria. Search methods We undertook a comprehensive search of the following databases up to 31 December 2013: Cochrane Infectious Diseases Group Specialized Register; MEDLINE; EMBASE; MEDION; Science Citation Index; Web of Knowledge; African Index Medicus; LILACS; and IndMED. Selection criteria Studies comparing RDTs with a reference standard (microscopy or polymerase chain reaction) in blood samples from a random or consecutive series of patients attending ambulatory health facilities with symptoms suggestive of malaria in non-falciparum endemic areas. Data collection and analysis For each study, two review authors independently extracted a standard set of data using a tailored data extraction form. We grouped comparisons by type of RDT (defined by the combinations of antibodies used), and combined in meta-analysis where appropriate. Average sensitivities and

  18. Antigenic Variation in Plasmodium falciparum.

    PubMed

    Petter, Michaela; Duffy, Michael F

    2015-01-01

    Plasmodium falciparum is the protozoan parasite that causes most malaria-associated morbidity and mortality in humans with over 500,000 deaths annually. The disease symptoms are associated with repeated cycles of invasion and asexual multiplication inside red blood cells of the parasite. Partial, non-sterile immunity to P. falciparum malaria develops only after repeated infections and continuous exposure. The successful evasion of the human immune system relies on the large repertoire of antigenically diverse parasite proteins displayed on the red blood cell surface and on the merozoite membrane where they are exposed to the human immune system. Expression switching of these polymorphic proteins between asexual parasite generations provides an efficient mechanism to adapt to the changing environment in the host and to maintain chronic infection. This chapter discusses antigenic diversity and variation in the malaria parasite and our current understanding of the molecular mechanisms that direct the expression of these proteins. PMID:26537377

  19. Plasmodium vivax Transmission in Africa

    PubMed Central

    Howes, Rosalind E.; Reiner Jr., Robert C.; Battle, Katherine E.; Longbottom, Joshua; Mappin, Bonnie; Ordanovich, Dariya; Tatem, Andrew J.; Drakeley, Chris; Gething, Peter W.; Zimmerman, Peter A.; Smith, David L.; Hay, Simon I.

    2015-01-01

    Malaria in sub-Saharan Africa has historically been almost exclusively attributed to Plasmodium falciparum (Pf). Current diagnostic and surveillance systems in much of sub-Saharan Africa are not designed to identify or report non-Pf human malaria infections accurately, resulting in a dearth of routine epidemiological data about their significance. The high prevalence of Duffy negativity provided a rationale for excluding the possibility of Plasmodium vivax (Pv) transmission. However, review of varied evidence sources including traveller infections, community prevalence surveys, local clinical case reports, entomological and serological studies contradicts this viewpoint. Here, these data reports are weighted in a unified framework to reflect the strength of evidence of indigenous Pv transmission in terms of diagnostic specificity, size of individual reports and corroboration between evidence sources. Direct evidence was reported from 21 of the 47 malaria-endemic countries studied, while 42 countries were attributed with infections of visiting travellers. Overall, moderate to conclusive evidence of transmission was available from 18 countries, distributed across all parts of the continent. Approximately 86.6 million Duffy positive hosts were at risk of infection in Africa in 2015. Analysis of the mechanisms sustaining Pv transmission across this continent of low frequency of susceptible hosts found that reports of Pv prevalence were consistent with transmission being potentially limited to Duffy positive populations. Finally, reports of apparent Duffy-independent transmission are discussed. While Pv is evidently not a major malaria parasite across most of sub-Saharan Africa, the evidence presented here highlights its widespread low-level endemicity. An increased awareness of Pv as a potential malaria parasite, coupled with policy shifts towards species-specific diagnostics and reporting, will allow a robust assessment of the public health significance of Pv, as well

  20. Plasmodium vivax Transmission in Africa.

    PubMed

    Howes, Rosalind E; Reiner, Robert C; Battle, Katherine E; Longbottom, Joshua; Mappin, Bonnie; Ordanovich, Dariya; Tatem, Andrew J; Drakeley, Chris; Gething, Peter W; Zimmerman, Peter A; Smith, David L; Hay, Simon I

    2015-11-01

    Malaria in sub-Saharan Africa has historically been almost exclusively attributed to Plasmodium falciparum (Pf). Current diagnostic and surveillance systems in much of sub-Saharan Africa are not designed to identify or report non-Pf human malaria infections accurately, resulting in a dearth of routine epidemiological data about their significance. The high prevalence of Duffy negativity provided a rationale for excluding the possibility of Plasmodium vivax (Pv) transmission. However, review of varied evidence sources including traveller infections, community prevalence surveys, local clinical case reports, entomological and serological studies contradicts this viewpoint. Here, these data reports are weighted in a unified framework to reflect the strength of evidence of indigenous Pv transmission in terms of diagnostic specificity, size of individual reports and corroboration between evidence sources. Direct evidence was reported from 21 of the 47 malaria-endemic countries studied, while 42 countries were attributed with infections of visiting travellers. Overall, moderate to conclusive evidence of transmission was available from 18 countries, distributed across all parts of the continent. Approximately 86.6 million Duffy positive hosts were at risk of infection in Africa in 2015. Analysis of the mechanisms sustaining Pv transmission across this continent of low frequency of susceptible hosts found that reports of Pv prevalence were consistent with transmission being potentially limited to Duffy positive populations. Finally, reports of apparent Duffy-independent transmission are discussed. While Pv is evidently not a major malaria parasite across most of sub-Saharan Africa, the evidence presented here highlights its widespread low-level endemicity. An increased awareness of Pv as a potential malaria parasite, coupled with policy shifts towards species-specific diagnostics and reporting, will allow a robust assessment of the public health significance of Pv, as well

  1. [Emerging and spread of the fifth Plasmodium spp. pathogenic for human malaria: Plasmodium knowlesi].

    PubMed

    Sabbatani, Sergio; Fiorino, Sirio; Manfredi, Roberto

    2010-02-01

    The beginning of the third millennium has been characterized by the emerging and progressive characterization of a novel malaria Plasmodium pathogen of simian origin (Plasmodium knowlesi), which now represents the fifth human malaria parasite. Evolutionary, environmental, and diagnostic-clinical features are briefly outlined on the ground of the most recent literature evidences.

  2. Malaria, Plasmodium falciparum and its apicoplast.

    PubMed

    Kalanon, Ming; McFadden, Geoffrey I

    2010-06-01

    Malaria, which is caused by species of the parasite genus Plasmodium, remains a major global health problem. A vestigial plastid homologous with the chloroplasts of plants and algae was discovered in malaria and related parasites from the phylum Apicomplexa and has radically changed our view of the evolutionary origins of these disease-causing protists. We now recognize that this large group of parasites had a photosynthetic ancestry and were converted into parasitism early in the evolution of animals. Apicomplexans have probably been parasitizing the animal kingdom for more than 500 million years. The relic plastid persists in most apicomplexans and is an essential component. Perturbation of apicoplast function or inheritance results in parasite death, making the organelle a promising target for chemotherapy. Plastids, including those of malaria parasites, are essentially reduced endosymbiotic bacteria living inside a eukaryotic host. This means that plastids have bacterial-type metabolic pathways and housekeeping processes, all of which are vulnerable to antibacterial compounds. Indeed, many antibacterials kill malaria parasites by blocking essential processes in the plastid. Furthermore, a range of herbicides that target plastid metabolism of undesired plants are also parasiticidal, making them potential new leads for antimalarial drugs. In the present review, we examine the evolutionary origins of the malaria parasite's plastid by endosymbiosis and outline the recent findings on how the organelle imports nuclear-encoded proteins through a set of translocation machineries in the membranes that bound the organelle.

  3. A large proportion of asymptomatic Plasmodium infections with low and sub-microscopic parasite densities in the low transmission setting of Temotu Province, Solomon Islands: challenges for malaria diagnostics in an elimination setting

    PubMed Central

    2010-01-01

    Background Many countries are scaling up malaria interventions towards elimination. This transition changes demands on malaria diagnostics from diagnosing ill patients to detecting parasites in all carriers including asymptomatic infections and infections with low parasite densities. Detection methods suitable to local malaria epidemiology must be selected prior to transitioning a malaria control programme to elimination. A baseline malaria survey conducted in Temotu Province, Solomon Islands in late 2008, as the first step in a provincial malaria elimination programme, provided malaria epidemiology data and an opportunity to assess how well different diagnostic methods performed in this setting. Methods During the survey, 9,491 blood samples were collected and examined by microscopy for Plasmodium species and density, with a subset also examined by polymerase chain reaction (PCR) and rapid diagnostic tests (RDTs). The performances of these diagnostic methods were compared. Results A total of 256 samples were positive by microscopy, giving a point prevalence of 2.7%. The species distribution was 17.5% Plasmodium falciparum and 82.4% Plasmodium vivax. In this low transmission setting, only 17.8% of the P. falciparum and 2.9% of P. vivax infected subjects were febrile (≥38°C) at the time of the survey. A significant proportion of infections detected by microscopy, 40% and 65.6% for P. falciparum and P. vivax respectively, had parasite density below 100/μL. There was an age correlation for the proportion of parasite density below 100/μL for P. vivax infections, but not for P. falciparum infections. PCR detected substantially more infections than microscopy (point prevalence of 8.71%), indicating a large number of subjects had sub-microscopic parasitemia. The concordance between PCR and microscopy in detecting single species was greater for P. vivax (135/162) compared to P. falciparum (36/118). The malaria RDT detected the 12 microscopy and PCR positive P

  4. Variation in the relationship between anti-MSP-1(19) antibody response and age in children infected with Plasmodium falciparum during the dry and rainy seasons.

    PubMed

    Omosun, Y O; Anumudu, C I; Adoro, S; Odaibo, A B; Sodeinde, O; Holder, A A; Nwagwu, M; Nwuba, R I

    2005-09-01

    Malaria remains a major parasitic disease in Africa, with 300-500 million new infections each year. There is therefore an urgent need for the development of new effective measures, including vaccines. Plasmodium falciparum merozoite surface protein-1(19) (MSP-1(19)) is a prime candidate for a blood-stage malaria vaccine. Blood samples were collected from children aged 10 days to 15 years in the months of January-March (N = 351) and October-November (N = 369) corresponding to the dry and rainy seasons, respectively. P. falciparum infection was determined by microscopy and enzyme linked immunosorbent assay (ELISA) was used to determine the total IgG and IgG subclasses. There was a significant increase in the mean anti-MSP-1(19) antibody titre in the dry season (p < 0.05), compared to the rainy season. A significantly positive correlation between the anti-MSP-1(19) antibody titre and parasite density (p < 0.01, r = 0.138) was observed. In the rainy season, unlike in the dry season, P. falciparum positive children had higher anti-MSP-1(19) antibody titres than P. falciparum negative children and this difference was significant (p < 0.05). When all individuals were grouped together, the anti-MSP-1(19) antibody titre increased with age in both seasons (r = 0.186 and 0.002), this increase was more apparent in the dry season. However, when the study population was divided into P. falciparum positive and negative groups, it was observed that in the rainy season, there was a negative correlation between anti-MSP-1(19) titre and age in P. falciparum positive individuals, while those who were P. falciparum negative had a positive correlation between anti-MSP-1(19) titre and age. Analysis of anti-MSP-1(19) IgG subclass showed that IgG1 and IgG3 mean titres were highest in both the dry and rainy seasons with an increase in the mean antibody titres for IgG1, IgG2 and IgG3 in the rainy season. In the dry season there was a positive correlation between IgG1, IgG2, and IgG3 titres

  5. Helminth Parasites Alter Protection against Plasmodium Infection

    PubMed Central

    Salazar-Castañon, Víctor H.; Legorreta-Herrera, Martha

    2014-01-01

    More than one-third of the world's population is infected with one or more helminthic parasites. Helminth infections are prevalent throughout tropical and subtropical regions where malaria pathogens are transmitted. Malaria is the most widespread and deadliest parasitic disease. The severity of the disease is strongly related to parasite density and the host's immune responses. Furthermore, coinfections between both parasites occur frequently. However, little is known regarding how concomitant infection with helminths and Plasmodium affects the host's immune response. Helminthic infections are frequently massive, chronic, and strong inductors of a Th2-type response. This implies that infection by such parasites could alter the host's susceptibility to subsequent infections by Plasmodium. There are a number of reports on the interactions between helminths and Plasmodium; in some, the burden of Plasmodium parasites increased, but others reported a reduction in the parasite. This review focuses on explaining many of these discrepancies regarding helminth-Plasmodium coinfections in terms of the effects that helminths have on the immune system. In particular, it focuses on helminth-induced immunosuppression and the effects of cytokines controlling polarization toward the Th1 or Th2 arms of the immune response. PMID:25276830

  6. Helminth parasites alter protection against Plasmodium infection.

    PubMed

    Salazar-Castañon, Víctor H; Legorreta-Herrera, Martha; Rodriguez-Sosa, Miriam

    2014-01-01

    More than one-third of the world's population is infected with one or more helminthic parasites. Helminth infections are prevalent throughout tropical and subtropical regions where malaria pathogens are transmitted. Malaria is the most widespread and deadliest parasitic disease. The severity of the disease is strongly related to parasite density and the host's immune responses. Furthermore, coinfections between both parasites occur frequently. However, little is known regarding how concomitant infection with helminths and Plasmodium affects the host's immune response. Helminthic infections are frequently massive, chronic, and strong inductors of a Th2-type response. This implies that infection by such parasites could alter the host's susceptibility to subsequent infections by Plasmodium. There are a number of reports on the interactions between helminths and Plasmodium; in some, the burden of Plasmodium parasites increased, but others reported a reduction in the parasite. This review focuses on explaining many of these discrepancies regarding helminth-Plasmodium coinfections in terms of the effects that helminths have on the immune system. In particular, it focuses on helminth-induced immunosuppression and the effects of cytokines controlling polarization toward the Th1 or Th2 arms of the immune response.

  7. Occurrence of Plasmodium in Anatidae

    USGS Publications Warehouse

    Herman, C.M.; Kocan, R.M.

    1970-01-01

    Until a little over a decade ago reports of Plasrnodium in geese, ducks, and swans were the result of examination of single blood smears from wild birds. One would gather from the earlier studies that Anatidae are infrequently infected. During the past decade we have conducted studies on prevalence of Plasmodium by an isodiagnosis technique, inoculating blood from wild birds into captive young geese, ducks, and other species of birds and determining the status of infection in the donors by examination of repetitive blood smears from the recipients. Examination by this technique of a series of adult Canada geese from the Seney National Wildlife Refuge in northern Michigan uncovered a prevalence of 60% during five successive years. Domestic geese were the primary recipients but we found that several other species of geese, ducks, and gulls were also susceptible. Similar studies on Canada geese from other areas (Maryland, New Jersey, New York, and southern Michigan) uncovered infection rates from zero to 27%. Following isolation of Plasmodlum in a single canvasback duck (Aythya valisineria) in southern Michigan by inoculation into a domestic duck, a series of 88 canvasbacks from Chesapeake Bay in Maryland this winter uncovered an infection rate of 27%. The most common parasite observed in both the geese and was as P. circumflexum.

  8. Arguments against Chemoprophylaxis in Areas at Low Risk for Chloroquine-Resistant Plasmodium falciparum.

    PubMed

    Armengaud

    1995-03-01

    Chemoprophylaxis of malaria prevents the disease not the infection (suppressive chemoprophylaxis) with "high levels of confusion and low levels of compliance." The magnitude of danger of contracting malaria for travelers varies in several endemic zones. In West Africa, without prophylaxis, malaria is estimated to have an incidence of 1.4% per person per month. In South and Central America, the incidence is 0.05 and 0.01% per month, respectively. In Asia, the transmission and percentage of infection due to Plasmodium falciparum is much lower. The dangers of chemoprophylaxis in an area at low risk for chloroquine resistant P. falciparum are a reality. Incompletely active drugs change clinical manifestations, and changes in clinical manifestations delay the establishment of a correct diagnosis. The rate of adverse events is 15-20%, and hospitalization due to side effects of prophylaxis occurs in one in 10,000 travelers. Neuropsychiatric side effects have been reported with both mefloquine and chloroquine. A false sense of security can hinder a physician practicing in a nonendemic area from thinking of malaria when a traveler returns with fever. To complicate the picture, in many countries, there is an emerging drug resistance in P. falciparum as well as an emerging chloroquine resistance in P. vivax strains (20% in New Guinea and Irian Jaya). In short, no available chemoprophylaxis is free from toxicity, and its efficacy is never 100%. Alternatives to conventional chemoprophylaxis are encouraged in areas of low morbidity of malaria. In areas where P. vivax occurs primarily, and when the risk of serious side effects from chemoprophylaxis outweighs the risk of life threatening P. falciparum infection, there are four alternative strategies.2,3 The first strategy is that the traveler avoid mosquito bites. With a compulsive attitude, a high degree of protection can be realized with the proper use of pyrethrum-impregnated mosquito netting, topical DEET-containing insect

  9. Antibody responses to Plasmodium falciparum and Plasmodium vivax blood-stage and sporozoite antigens in the postpartum period

    PubMed Central

    McLean, Alistair R. D.; Boel, Machteld E.; McGready, Rose; Ataide, Ricardo; Drew, Damien; Tsuboi, Takafumi; Beeson, James G.; Nosten, François; Simpson, Julie A.; Fowkes, Freya J. I.

    2016-01-01

    During pregnancy a variety of immunological changes occur to accommodate the fetus. It is unknown whether these changes continue to affect humoral immunity postpartum or how quickly they resolve. IgG levels were measured to P. falciparum and P. vivax antigens in 201 postpartum and 201 controls over 12 weeks. Linear mixed-effects models assessed antibody maintenance over time and the effect of microscopically confirmed Plasmodium spp. infection on antibody levels, and whether this was different in postpartum women compared with control women. Postpartum women had reduced Plasmodium spp. antibody levels compared to controls at baseline. Over 12 weeks, mean antibody levels in postpartum women increased to levels observed in control women. Microscopically confirmed P. falciparum and P. vivax infections during follow-up were associated with an increase in species-specific antibodies with similar magnitudes of boosting observed in postpartum and control women. Antibodies specific for pregnancy-associated, VAR2CSA-expressing parasites did not rapidly decline postpartum and did not boost in response to infection in either postpartum or control women. After pregnancy, levels of malaria-specific antibodies were reduced, but recovered to levels seen in control women. There was no evidence of an impaired ability to mount a boosting response in postpartum women. PMID:27558000

  10. Antibody responses to Plasmodium falciparum and Plasmodium vivax blood-stage and sporozoite antigens in the postpartum period.

    PubMed

    McLean, Alistair R D; Boel, Machteld E; McGready, Rose; Ataide, Ricardo; Drew, Damien; Tsuboi, Takafumi; Beeson, James G; Nosten, François; Simpson, Julie A; Fowkes, Freya J I

    2016-01-01

    During pregnancy a variety of immunological changes occur to accommodate the fetus. It is unknown whether these changes continue to affect humoral immunity postpartum or how quickly they resolve. IgG levels were measured to P. falciparum and P. vivax antigens in 201 postpartum and 201 controls over 12 weeks. Linear mixed-effects models assessed antibody maintenance over time and the effect of microscopically confirmed Plasmodium spp. infection on antibody levels, and whether this was different in postpartum women compared with control women. Postpartum women had reduced Plasmodium spp. antibody levels compared to controls at baseline. Over 12 weeks, mean antibody levels in postpartum women increased to levels observed in control women. Microscopically confirmed P. falciparum and P. vivax infections during follow-up were associated with an increase in species-specific antibodies with similar magnitudes of boosting observed in postpartum and control women. Antibodies specific for pregnancy-associated, VAR2CSA-expressing parasites did not rapidly decline postpartum and did not boost in response to infection in either postpartum or control women. After pregnancy, levels of malaria-specific antibodies were reduced, but recovered to levels seen in control women. There was no evidence of an impaired ability to mount a boosting response in postpartum women. PMID:27558000

  11. Characterization of the Plasmodium Interspersed Repeats (PIR) proteins of Plasmodium chabaudi indicates functional diversity

    PubMed Central

    Yam, Xue Yan; Brugat, Thibaut; Siau, Anthony; Lawton, Jennifer; Wong, Daniel S.; Farah, Abdirahman; Twang, Jing Shun; Gao, Xiaohong; Langhorne, Jean; Preiser, Peter R.

    2016-01-01

    Plasmodium multigene families play a central role in the pathogenesis of malaria. The Plasmodium interspersed repeat (pir) genes comprise the largest multigene family in many Plasmodium spp. However their function(s) remains unknown. Using the rodent model of malaria, Plasmodium chabaudi, we show that individual CIR proteins have differential localizations within infected red cell (iRBC), suggesting different functional roles in a blood-stage infection. Some CIRs appear to be located on the surface of iRBC and merozoites and are therefore well placed to interact with host molecules. In line with this hypothesis, we show for the first time that a subset of recombinant CIRs bind mouse RBCs suggesting a role for CIR in rosette formation and/or invasion. Together, our results unravel differences in subcellular localization and ability to bind mouse erythrocytes between the members of the cir family, which strongly suggest different functional roles in a blood-stage infection. PMID:26996203

  12. Characterization of the Plasmodium Interspersed Repeats (PIR) proteins of Plasmodium chabaudi indicates functional diversity.

    PubMed

    Yam, Xue Yan; Brugat, Thibaut; Siau, Anthony; Lawton, Jennifer; Wong, Daniel S; Farah, Abdirahman; Twang, Jing Shun; Gao, Xiaohong; Langhorne, Jean; Preiser, Peter R

    2016-01-01

    Plasmodium multigene families play a central role in the pathogenesis of malaria. The Plasmodium interspersed repeat (pir) genes comprise the largest multigene family in many Plasmodium spp. However their function(s) remains unknown. Using the rodent model of malaria, Plasmodium chabaudi, we show that individual CIR proteins have differential localizations within infected red cell (iRBC), suggesting different functional roles in a blood-stage infection. Some CIRs appear to be located on the surface of iRBC and merozoites and are therefore well placed to interact with host molecules. In line with this hypothesis, we show for the first time that a subset of recombinant CIRs bind mouse RBCs suggesting a role for CIR in rosette formation and/or invasion. Together, our results unravel differences in subcellular localization and ability to bind mouse erythrocytes between the members of the cir family, which strongly suggest different functional roles in a blood-stage infection. PMID:26996203

  13. Detectability of Plasmodium falciparum clones

    PubMed Central

    2010-01-01

    Background In areas of high transmission people often harbour multiple clones of Plasmodium falciparum, but even PCR-based diagnostic methods can only detect a fraction (the detectability, q) of all clones present in a host. Accurate measurements of detectability are desirable since it affects estimates of multiplicity of infection, prevalence, and frequency of breakthrough infections in clinical drug trials. Detectability can be estimated by typing repeated samples from the same host but it has been unclear what should be the time interval between the samples and how the data should be analysed. Methods A longitudinal molecular study was conducted in the Kassena-Nankana district in northern Ghana. From each of the 80 participants, four finger prick samples were collected over a period of 8 days, and tested for presence of different Merozoite Surface Protein (msp) 2 genotypes. Implications for estimating q were derived from these data by comparing the fit of statistical models of serial dependence and over-dispersion. Results The distribution of the frequencies of detection for msp2 genotypes was close to binomial if the time span between consecutive blood samples was at least 7 days. For shorter intervals the probabilities of detection were positively correlated, i.e. the shorter the interval between two blood collections, the more likely the diagnostic results matched for a particular genotype. Estimates of q were rather insensitive to the statistical model fitted. Conclusions A simple algorithm based on analysing blood samples collected 7 days apart is justified for generating robust estimates of detectability. The finding of positive correlation of detection probabilities for short time intervals argues against imperfect detection being directly linked to the 48-hour periodicity of P. falciparum. The results suggest that the detectability of a given parasite clone changes over time, at an unknown rate, but fast enough to regard blood samples taken one week

  14. Targeting molecular interactions essential for Plasmodium sexual reproduction

    PubMed Central

    Vega-Rodriguez, Joel; Perez-Barreto, Davinia; Ruiz-Reyes, Antonio; Jacobs-Lorena, Marcelo

    2015-01-01

    Summary Malaria remains one of the most devastating infectious diseases, killing up to a million people every year. Whereas much progress has been made in understanding the life cycle of the parasite in the human host and in the mosquito vector, significant gaps of knowledge remain. Fertilization of malaria parasites, a process that takes place in the lumen of the mosquito midgut, is poorly understood and the molecular interactions (receptor–ligand) required for Plasmodium fertilization remain elusive. By use of a phage display library, we identified FG1 (Female Gamete peptide 1), a peptide that binds specifically to the surface of female Plasmodium berghei gametes. Importantly, FG1 but not a scrambled version of the peptide, strongly reduces P. berghei oocyst formation by interfering with fertilization. In addition, FG1 also inhibits P. falciparum oocyst formation suggesting that the peptide binds to a molecule on the surface of the female gamete whose structure is conserved. Identification of the molecular interactions disrupted by the FG1 peptide may lead to the development of novel malaria transmission-blocking strategies. PMID:25944054

  15. Spatial Epidemiology of Plasmodium vivax, Afghanistan

    PubMed Central

    Leslie, Toby; Kolaczinski, Kate; Mohsen, Engineer; Mehboob, Najeebullah; Saleheen, Sarah; Khudonazarov, Juma; Freeman, Tim; Clements, Archie; Rowland, Mark; Kolaczinski, Jan

    2006-01-01

    Plasmodium vivax is endemic to many areas of Afghanistan. Geographic analysis helped highlight areas of malaria risk and clarified ecologic risk factors for transmission. Remote sensing enabled development of a risk map, thereby providing a valuable tool to help guide malaria control strategies. PMID:17176583

  16. Energy metabolism affects susceptibility of A. gambiae mosquitoes to Plasmodium infection

    PubMed Central

    Oliveira, Jose Henrique M.; Gonçalves, Renata L.S.; Oliveira, Giselle A.; Oliveira, Pedro L.; Oliveira, Marcus F.; Barillas-Mury, Carolina

    2011-01-01

    Previous studies showed that A. gambiae L35 females, which are refractory (R) to Plasmodium infection, express higher levels of genes involved in redox-metabolism and mitochondrial respiration than susceptible (S) G3 females. Our studies revealed that R females have reduced longevity, faster utilization of lipid reserves, impaired mitochondrial State-3 respiration, increased rate of mitochondrial electron leak and higher expression levels of several glycolytic enzyme genes. Furthermore, when State-3 respiration was reduced in S females by silencing expression of the adenine nucleotide translocator (ANT), hydrogen peroxide generation was higher and the mRNA levels of lactate dehydrogenase increased in the midgut, while the prevalence and intensity of P. berghei infection were significantly reduced. We conclude that there are broad metabolic differences between R and S An. gambiae mosquitoes that influence their susceptibility to Plasmodium infection. PMID:21320598

  17. Plasmodium falciparum In Vitro Resistance to Monodesethylamodiaquine, Dakar, Senegal, 2014.

    PubMed

    Fall, Bécaye; Madamet, Marylin; Camara, Cheikhou; Amalvict, Rémy; Fall, Mansour; Nakoulima, Aminata; Diatta, Bakary; Diémé, Yaya; Wade, Boubacar; Pradines, Bruno

    2016-05-01

    We successfully cultured 36 Plasmodium falciparum isolates from blood samples of 44 malaria patients admitted to the Hôpital Principal de Dakar (Dakar, Senegal) during August-December 2014. The prevalence of isolates with in vitro reduced susceptibility was 30.6% for monodesethylamodiaquine, 52.8% for chloroquine, 44.1% for mefloquine, 16.7% for doxycycline, 11.8% for piperaquine, 8.3% for artesunate, 5.9% for pyronaridine, 2.8% for quinine and dihydroartemisinin, and 0.0% for lumefantrine. The prevalence of isolates with reduced in vitro susceptibility to the artemisinin-based combination therapy partner monodesethylamodiaquine increased from 5.6% in 2013 to 30.6% in 2014. Because of the increased prevalence of P. falciparum parasites with impaired in vitro susceptibility to monodesethylamodiaquine, the implementation of in vitro and in vivo surveillance of all artemisinin-based combination therapy partners is warranted. PMID:27088703

  18. Plasmodium falciparum In Vitro Resistance to Monodesethylamodiaquine, Dakar, Senegal, 2014

    PubMed Central

    Fall, Bécaye; Madamet, Marylin; Camara, Cheikhou; Amalvict, Rémy; Fall, Mansour; Nakoulima, Aminata; Diatta, Bakary; Diémé, Yaya; Wade, Boubacar

    2016-01-01

    We successfully cultured 36 Plasmodium falciparum isolates from blood samples of 44 malaria patients admitted to the Hôpital Principal de Dakar (Dakar, Senegal) during August–December 2014. The prevalence of isolates with in vitro reduced susceptibility was 30.6% for monodesethylamodiaquine, 52.8% for chloroquine, 44.1% for mefloquine, 16.7% for doxycycline, 11.8% for piperaquine, 8.3% for artesunate, 5.9% for pyronaridine, 2.8% for quinine and dihydroartemisinin, and 0.0% for lumefantrine. The prevalence of isolates with reduced in vitro susceptibility to the artemisinin-based combination therapy partner monodesethylamodiaquine increased from 5.6% in 2013 to 30.6% in 2014. Because of the increased prevalence of P. falciparum parasites with impaired in vitro susceptibility to monodesethylamodiaquine, the implementation of in vitro and in vivo surveillance of all artemisinin-based combination therapy partners is warranted. PMID:27088703

  19. α2-Macroglobulin Can Crosslink Multiple Plasmodium falciparum Erythrocyte Membrane Protein 1 (PfEMP1) Molecules and May Facilitate Adhesion of Parasitized Erythrocytes.

    PubMed

    Stevenson, Liz; Laursen, Erik; Cowan, Graeme J; Bandoh, Betty; Barfod, Lea; Cavanagh, David R; Andersen, Gregers R; Hviid, Lars

    2015-07-01

    Rosetting, the adhesion of Plasmodium falciparum-infected erythrocytes to uninfected erythrocytes, involves clonal variants of the parasite protein P. falciparum erythrocyte membrane protein 1 (PfEMP1) and soluble serum factors. While rosetting is a well-known phenotypic marker of parasites associated with severe malaria, the reason for this association remains unclear, as do the molecular details of the interaction between the infected erythrocyte (IE) and the adhering erythrocytes. Here, we identify for the first time a single serum factor, the abundant serum protease inhibitor α2-macroglobulin (α2M), which is both required and sufficient for rosetting mediated by the PfEMP1 protein HB3VAR06 and some other rosette-mediating PfEMP1 proteins. We map the α2M binding site to the C terminal end of HB3VAR06, and demonstrate that α2M can bind at least four HB3VAR06 proteins, plausibly augmenting their combined avidity for host receptors. IgM has previously been identified as a rosette-facilitating soluble factor that acts in a similar way, but it cannot induce rosetting on its own. This is in contrast to α2M and probably due to the more limited cross-linking potential of IgM. Nevertheless, we show that IgM works synergistically with α2M and markedly lowers the concentration of α2M required for rosetting. Finally, HB3VAR06+ IEs share the capacity to bind α2M with subsets of genotypically distinct P. falciparum isolates forming rosettes in vitro and of patient parasite isolates ex vivo. Together, our results are evidence that P. falciparum parasites exploit α2M (and IgM) to expand the repertoire of host receptors available for PfEMP1-mediated IE adhesion, such as the erythrocyte carbohydrate moieties that lead to formation of rosettes. It is likely that this mechanism also affects IE adhesion to receptors on vascular endothelium. The study opens opportunities for broad-ranging immunological interventions targeting the α2M--(and IgM-) binding domains of PfEMP1

  20. Novel phenotypic assays for the detection of artemisinin-resistant Plasmodium falciparum malaria in Cambodia: in-vitro and ex-vivo drug-response studies

    PubMed Central

    Witkowski, Benoit; Amaratunga, Chanaki; Khim, Nimol; Sreng, Sokunthea; Chim, Pheaktra; Kim, Saorin; Lim, Pharath; Mao, Sivanna; Sopha, Chantha; Sam, Baramey; Anderson, Jennifer M; Duong, Socheat; Chuor, Char Meng; Taylor, Walter R J; Suon, Seila; Mercereau-Puijalon, Odile; Fairhurst, Rick M; Menard, Didier

    2016-01-01

    Summary Background Artemisinin resistance in Plasmodium falciparum lengthens parasite clearance half-life during artemisinin monotherapy or artemisinin-based combination therapy. Absence of in-vitro and ex-vivo correlates of artemisinin resistance hinders study of this phenotype. We aimed to assess whether an in-vitro ring-stage survival assay (RSA) can identify culture-adapted P falciparum isolates from patients with slow-clearing or fast-clearing infections, to investigate the stage-dependent susceptibility of parasites to dihydroartemisinin in the in-vitro RSA, and to assess whether an ex-vivo RSA can identify artemisinin-resistant P falciparum infections. Methods We culture-adapted parasites from patients with long and short parasite clearance half-lives from a study done in Pursat, Cambodia, in 2010 (registered with ClinicalTrials.gov, number NCT00341003) and used novel in-vitro survival assays to explore the stage-dependent susceptibility of slow-clearing and fast-clearing parasites to dihydroartemisinin. In 2012, we implemented the RSA in prospective parasite clearance studies in Pursat, Preah Vihear, and Ratanakiri, Cambodia (NCT01736319), to measure the ex-vivo responses of parasites from patients with malaria. Continuous variables were compared with the Mann-Whitney U test. Correlations were analysed with the Spearman correlation test. Findings In-vitro survival rates of culture-adapted parasites from 13 slow-clearing and 13 fast-clearing infections differed significantly when assays were done on 0–3 h ring-stage parasites (10·88% vs 0·23%; p=0·007). Ex-vivo survival rates significantly correlated with in-vivo parasite clearance half-lives (n=30, r=0·74, 95% CI 0·50–0·87; p<0·0001). Interpretation The in-vitro RSA of 0–3 h ring-stage parasites provides a platform for the molecular characterisation of artemisinin resistance. The ex-vivo RSA can be easily implemented where surveillance for artemisinin resistance is needed. Funding Institut

  1. Enhanced Basophil Reactivities during Severe Malaria and Their Relationship with the Plasmodium falciparum Histamine-Releasing Factor Translationally Controlled Tumor Protein

    PubMed Central

    Pelleau, Stéphane; Diop, Sylvie; Dia Badiane, Méry; Vitte, Joana; Beguin, Pierre; Nato, Farida; Diop, Bernard M.; Bongrand, Pierre; Parzy, Daniel

    2012-01-01

    Recent studies suggest shared pathogenic pathways during malaria and allergy. Indeed, IgE, histamine, and the parasite-derived Plasmodium falciparum histamine-releasing factor translationally controlled tumor protein (PfTCTP) can be found at high levels in serum from patients experiencing malaria, but their relationship with basophil activation remains unknown. We recruited P. falciparum-infected patients in Senegal with mild malaria (MM; n = 19) or severe malaria (SM; n = 9) symptoms and healthy controls (HC; n = 38). Levels of serum IgE, PfTCTP, and IgG antibodies against PfTCTP were determined by enzyme-linked immunosorbent assays (ELISA). Basophil reactivities to IgE-dependent and -independent stimulations were measured ex vivo using fresh blood by looking at the expression level of the basophil activation marker CD203c with flow cytometry. Unstimulated basophils from MM had significantly lower levels of CD203c expression compared to those from HC and SM. After normalization on this baseline level, basophils from SM showed an enhanced reactivity to calcimycin (A23187) and hemozoin. Although SM reached higher median levels of activation after anti-IgE stimulation, great interindividual differences did not allow the results to reach statistical significance. When primed with recombinant TCTP before anti-IgE, qualitative differences in terms of a better ability to control excessive activation could be described for SM. IgE levels were very high in malaria patients, but concentrations in MM and SM were similar and were not associated with basophil responses, which demonstrates that the presence of IgE alone cannot explain the various basophil reactivities. Indeed, PfTCTP could be detected in 32% of patients, with higher concentrations for SM. These PfTCTP-positive patients displayed significantly higher basophil reactivities to any stimulus. Moreover, the absence of anti-PfTCTP IgG was associated with higher responses in SM but not MM. Our results show an

  2. Enhanced basophil reactivities during severe malaria and their relationship with the Plasmodium falciparum histamine-releasing factor translationally controlled tumor protein.

    PubMed

    Pelleau, Stéphane; Diop, Sylvie; Dia Badiane, Méry; Vitte, Joana; Beguin, Pierre; Nato, Farida; Diop, Bernard M; Bongrand, Pierre; Parzy, Daniel; Jambou, Ronan

    2012-08-01

    Recent studies suggest shared pathogenic pathways during malaria and allergy. Indeed, IgE, histamine, and the parasite-derived Plasmodium falciparum histamine-releasing factor translationally controlled tumor protein (PfTCTP) can be found at high levels in serum from patients experiencing malaria, but their relationship with basophil activation remains unknown. We recruited P. falciparum-infected patients in Senegal with mild malaria (MM; n = 19) or severe malaria (SM; n = 9) symptoms and healthy controls (HC; n = 38). Levels of serum IgE, PfTCTP, and IgG antibodies against PfTCTP were determined by enzyme-linked immunosorbent assays (ELISA). Basophil reactivities to IgE-dependent and -independent stimulations were measured ex vivo using fresh blood by looking at the expression level of the basophil activation marker CD203c with flow cytometry. Unstimulated basophils from MM had significantly lower levels of CD203c expression compared to those from HC and SM. After normalization on this baseline level, basophils from SM showed an enhanced reactivity to calcimycin (A23187) and hemozoin. Although SM reached higher median levels of activation after anti-IgE stimulation, great interindividual differences did not allow the results to reach statistical significance. When primed with recombinant TCTP before anti-IgE, qualitative differences in terms of a better ability to control excessive activation could be described for SM. IgE levels were very high in malaria patients, but concentrations in MM and SM were similar and were not associated with basophil responses, which demonstrates that the presence of IgE alone cannot explain the various basophil reactivities. Indeed, PfTCTP could be detected in 32% of patients, with higher concentrations for SM. These PfTCTP-positive patients displayed significantly higher basophil reactivities to any stimulus. Moreover, the absence of anti-PfTCTP IgG was associated with higher responses in SM but not MM. Our results show an

  3. Prevalence of Plasmodium falciparum resistance markers to sulfadoxine-pyrimethamine among pregnant women receiving intermittent preventive treatment for malaria in Uganda.

    PubMed

    Mbonye, Anthony K; Birungi, Josephine; Yanow, Stephanie K; Shokoples, Sandra; Malamba, Samuel; Alifrangis, Michael; Magnussen, Pascal

    2015-09-01

    The aim of this study was to assess the prevalence of mutations in Plasmodium falciparum dihydrofolate reductase (Pfdhfr) and dihydropteroate synthase (Pfdhps) genes among pregnant women using sulfadoxine-pyrimethamine (SP) as an intermittent preventive treatment (IPTp). A molecular epidemiological study of P. falciparum parasite resistance markers to SP was conducted from August 2010 to February 2012 in Mukono district in central Uganda. DNA was extracted from 413 P. falciparum-positive samples. Real-time PCR, followed by melting curve analysis, was used to characterize point mutations in the Pfdhfr and Pfdhps genes that are associated with SP resistance. The prevalence of the single-nucleotide mutations in Pfdhfr at codons 51I, 59R, and 108N and in Pfdhps at codons 437G and 540E was high (>98%), reaching 100% fixation after one dose of SP, while the prevalence of 581G was 3.3% at baseline, reaching 12.5% after one dose of SP. At baseline, the prevalence of Pfdhfr and Pfdhps quintuple mutations was 89%, whereas the sextuple mutations (including 581G) were not prevalent (3.9%), reaching 16.7% after one dose of SP. However, the numbers of infections at follow-up visits were small, and hence there was insufficient statistical power to test whether there was a true rise in the prevalence of this allele. The overall high frequency of Pfdhfr and Pfdhps quintuple mutations throughout pregnancy excluded further analyses of possible associations between certain haplotypes and the risk of lower birth weight and anemia. However, women infected with P. falciparum had 1.3-g/dl-lower hemoglobin levels (P = 0.001) and delivered babies with a 400-g-lower birth weight (P = 0.001) compared to nonparasitemic women. Despite this, 44 women who were P. falciparum positive at baseline became negative after one or two doses of SP (i.e., 50.5%), implying that SP-IPTp still has some efficacy. P. falciparum resistance markers to SP are high in this population, whereas P. falciparum

  4. Squalestatin Is an Inhibitor of Carotenoid Biosynthesis in Plasmodium falciparum

    PubMed Central

    Gabriel, Heloisa B.; Silva, Marcia F.; Kimura, Emília A.; Wunderlich, Gerhard

    2015-01-01

    The increasing resistance of malaria parasites to almost all available drugs calls for the characterization of novel targets and the identification of new compounds. Carotenoids are polyisoprenoids from plants, algae, and some bacteria, and they are biosynthesized by Plasmodium falciparum but not by mammalian cells. Biochemical and reverse genetics approaches were applied to demonstrate that phytoene synthase (PSY) is a key enzyme for carotenoid biosynthesis in P. falciparum and is essential for intraerythrocytic growth. The known PSY inhibitor squalestatin reduces biosynthesis of phytoene and kills parasites during the intraerythrocytic cycle. PSY-overexpressing parasites showed increased biosynthesis of phytoene and its derived product phytofluene and presented a squalestatin-resistant phenotype, suggesting that this enzyme is the primary target of action of this drug in the parasite. PMID:25779575

  5. Endemicity response timelines for Plasmodium falciparum elimination

    PubMed Central

    Smith, David L; Hay, Simon I

    2009-01-01

    Background The scaling up of malaria control and renewed calls for malaria eradication have raised interest in defining timelines for changes in malaria endemicity. Methods The epidemiological theory for the decline in the Plasmodium falciparum parasite rate (PfPR, the prevalence of infection) following intervention was critically reviewed and where necessary extended to consider superinfection, heterogeneous biting, and aging infections. Timelines for malaria control and elimination under different levels of intervention were then established using a wide range of candidate mathematical models. Analysis focused on the timelines from baseline to 1% and from 1% through the final stages of elimination. Results The Ross-Macdonald model, which ignores superinfection, was used for planning during the Global Malaria Eradication Programme (GMEP). In models that consider superinfection, PfPR takes two to three years longer to reach 1% starting from a hyperendemic baseline, consistent with one of the few large-scale malaria control trials conducted in an African population with hyperendemic malaria. The time to elimination depends fundamentally upon the extent to which malaria transmission is interrupted and the size of the human population modelled. When the PfPR drops below 1%, almost all models predict similar and proportional declines in PfPR in consecutive years from 1% through to elimination and that the waiting time to reduce PfPR from 10% to 1% and from 1% to 0.1% are approximately equal, but the decay rate can increase over time if infections senesce. Conclusion The theory described herein provides simple "rules of thumb" and likely time horizons for the impact of interventions for control and elimination. Starting from a hyperendemic baseline, the GMEP planning timelines, which were based on the Ross-Macdonald model with completely interrupted transmission, were inappropriate for setting endemicity timelines and they represent the most optimistic scenario for

  6. Plasmodium cynomolgi genome sequences provide insight into Plasmodium vivax and the monkey malaria clade

    PubMed Central

    Tachibana, Shin-Ichiro; Sullivan, Steven A.; Kawai, Satoru; Nakamura, Shota; Kim, Hyunjae R.; Goto, Naohisa; Arisue, Nobuko; Palacpac, Nirianne M. Q.; Honma, Hajime; Yagi, Masanori; Tougan, Takahiro; Katakai, Yuko; Kaneko, Osamu; Mita, Toshihiro; Kita, Kiyoshi; Yasutomi, Yasuhiro; Sutton, Patrick L.; Shakhbatyan, Rimma; Horii, Toshihiro; Yasunaga, Teruo; Barnwell, John W.; Escalante, Ananias A.; Carlton, Jane M.; Tanabe, Kazuyuki

    2013-01-01

    Plasmodium cynomolgi, a malaria parasite of Asian Old World monkeys, is the sister taxon of Plasmodium vivax, the most prevalent human malaria species outside Africa. Since P. cynomolgi shares many phenotypic, biologic and genetic characteristics of P. vivax, we generated draft genome sequences of three P. cynomolgi strains and performed comparative genomic analysis between them and P. vivax, as well as a third previously sequenced simian parasite, Plasmodium knowlesi. Here we show that genomes of the monkey malaria clade can be characterized by CNVs in multigene families involved in evasion of the human immune system and invasion of host erythrocytes. We identify genome-wide SNPs, microsatellites, and CNVs in the P. cynomolgi genome, providing a map of genetic variation for mapping parasite traits and studying parasite populations. The P. cynomolgi genome is a critical step in developing a model system for P. vivax research, and to counteract the neglect of P. vivax. PMID:22863735

  7. Branched tricarboxylic acid metabolism in Plasmodium falciparum.

    PubMed

    Olszewski, Kellen L; Mather, Michael W; Morrisey, Joanne M; Garcia, Benjamin A; Vaidya, Akhil B; Rabinowitz, Joshua D; Llinás, Manuel

    2010-08-01

    A central hub of carbon metabolism is the tricarboxylic acid cycle, which serves to connect the processes of glycolysis, gluconeogenesis, respiration, amino acid synthesis and other biosynthetic pathways. The protozoan intracellular malaria parasites (Plasmodium spp.), however, have long been suspected of possessing a significantly streamlined carbon metabolic network in which tricarboxylic acid metabolism plays a minor role. Blood-stage Plasmodium parasites rely almost entirely on glucose fermentation for energy and consume minimal amounts of oxygen, yet the parasite genome encodes all of the enzymes necessary for a complete tricarboxylic acid cycle. Here, by tracing (13)C-labelled compounds using mass spectrometry we show that tricarboxylic acid metabolism in the human malaria parasite Plasmodium falciparum is largely disconnected from glycolysis and is organized along a fundamentally different architecture from the canonical textbook pathway. We find that this pathway is not cyclic, but rather is a branched structure in which the major carbon sources are the amino acids glutamate and glutamine. As a consequence of this branched architecture, several reactions must run in the reverse of the standard direction, thereby generating two-carbon units in the form of acetyl-coenzyme A. We further show that glutamine-derived acetyl-coenzyme A is used for histone acetylation, whereas glucose-derived acetyl-coenzyme A is used to acetylate amino sugars. Thus, the parasite has evolved two independent production mechanisms for acetyl-coenzyme A with different biological functions. These results significantly clarify our understanding of the Plasmodium metabolic network and highlight the ability of altered variants of central carbon metabolism to arise in response to unique environments. PMID:20686576

  8. Plasmodium knowlesi infection: a diagnostic challenge

    PubMed Central

    Fan, Lijia; Lee, Shir Ying; Koay, Evelyn; Harkensee, Christian

    2013-01-01

    Plasmodium knowlesi malaria is an uncommon, but highly prevalent parasitic infection in parts of Malaysia. This is the case of a 14-year-old Singaporean boy presenting to our emergency department with an 11-day history of fever following a school trip to Malaysia. Hepatosplenomegaly was the only clinical finding; laboratory tests showed thrombocytopaenia, lymphopaenia, mild anaemia and liver transaminitis. Specific malaria antigen tests were negative, but the peripheral blood film showed plasmodia with atypical features, with a parasite load of 0.5%. PCR confirmed the diagnosis of P knowlesi. The patient was successfully treated with chloroquine. The clinical course of P knowlesi malaria is indistinguishable from that of Plasmodium falciparum. This case highlights the importance of taking detailed travel history, careful examination of malaria blood films and judicious use of molecular techniques. Antigen tests alone may have missed a malaria diagnosis altogether, while blood film examination may wrongly identify the species as Plasmodium malariae or P falciparum. Third-generation PCR assays can be used to reliably identify P knowlesi. PMID:23608876

  9. Suggestive evidence for Darwinian Selection against asparagine-linked glycans of Plasmodium falciparum and Toxoplasma gondii.

    PubMed

    Bushkin, G Guy; Ratner, Daniel M; Cui, Jike; Banerjee, Sulagna; Duraisingh, Manoj T; Jennings, Cameron V; Dvorin, Jeffrey D; Gubbels, Marc-Jan; Robertson, Seth D; Steffen, Martin; O'Keefe, Barry R; Robbins, Phillips W; Samuelson, John

    2010-02-01

    We are interested in asparagine-linked glycans (N-glycans) of Plasmodium falciparum and Toxoplasma gondii, because their N-glycan structures have been controversial and because we hypothesize that there might be selection against N-glycans in nucleus-encoded proteins that must pass through the endoplasmic reticulum (ER) prior to threading into the apicoplast. In support of our hypothesis, we observed the following. First, in protists with apicoplasts, there is extensive secondary loss of Alg enzymes that make lipid-linked precursors to N-glycans. Theileria makes no N-glycans, and Plasmodium makes a severely truncated N-glycan precursor composed of one or two GlcNAc residues. Second, secreted proteins of Toxoplasma, which uses its own 10-sugar precursor (Glc(3)Man(5)GlcNAc(2)) and the host 14-sugar precursor (Glc(3)Man(9)GlcNAc(2)) to make N-glycans, have very few sites for N glycosylation, and there is additional selection against N-glycan sites in its apicoplast-targeted proteins. Third, while the GlcNAc-binding Griffonia simplicifolia lectin II labels ER, rhoptries, and surface of plasmodia, there is no apicoplast labeling. Similarly, the antiretroviral lectin cyanovirin-N, which binds to N-glycans of Toxoplasma, labels ER and rhoptries, but there is no apicoplast labeling. We conclude that possible selection against N-glycans in protists with apicoplasts occurs by eliminating N-glycans (Theileria), reducing their length (Plasmodium), or reducing the number of N-glycan sites (Toxoplasma). In addition, occupation of N-glycan sites is markedly reduced in apicoplast proteins versus some secretory proteins in both Plasmodium and Toxoplasma.

  10. COMPETITION FOR RED BLOOD CELLS CAN ENHANCE PLASMODIUM VIVAX PARASITEMIA IN MIXED-SPECIES MALARIA INFECTIONS

    PubMed Central

    MCQUEEN, PHILIP G.; MCKENZIE, F. ELLIS

    2008-01-01

    We assess the consequences of competition for red blood cells (RBCs) in co-infections with the two major agents of human malaria, Plasmodium vivax and Plasmodium falciparum, using differential equations to model the population dynamics of RBCs and parasites. P. vivax parasitizes only the youngest RBCs, but this can reduce the broader RBC population susceptible to P. falciparum. We found that competition for RBCs typically causes one species to suppress the other, depending on their relative reproduction rates and timing of inoculation. However, if the species’ reproduction rates are nearly equal, transient increases in RBC production stimulated by the presence of P. falciparum may boost P. vivax parasitemia above its single-species infection level. Conversely, P. falciparum parasitemia is rarely enhanced above its single-species level. Furthermore, transients in RBC production can induce coupled oscillations in the parasitemia of both species. These results are remarkably robust to changes in model parameters. PMID:16837717

  11. Plasmodium falciparum: characterization of defined antigens by monoclonal antibodies.

    PubMed Central

    Perrin, L H; Ramirez, E; Er-Hsiang, L; Lambert, P H

    1980-01-01

    Monoclonal antibodies directed against Plasmodium falciparum detect stage-specific, species-specific and common antigenic determinants of Plasmodia. These antibodies provide new tools for purification and characterization of Plasmodium falciparum antigens in relation to future procedures for immunoprophylaxis. Images Fig. 2 PMID:6160002

  12. Mosquito transmission of wild turkey malaria, Plasmodium hermani.

    PubMed

    Young, M D; Nayar, J K; Forrester, D J

    1977-04-01

    Culex nigripalpus experimentally transmitted Plasmodium hermani, a plasmodium of wild turkeys (Meleagris gallopavo) in Florida. The mosquitoes were infected by feeding upon blood induced parasitemias in domestic turkey poults. The resulting sporozoites, transmitted by either mosquito bites or injection, produced malaria infections in domestic poults.

  13. Antimalarial activity of Malaysian Plectranthus amboinicus against Plasmodium berghei

    PubMed Central

    Ramli, Norazsida; Ahamed, Pakeer Oothuman Syed; Elhady, Hassan Mohamed; Taher, Muhammad

    2014-01-01

    Context: Malaria is a mosquito-borne disease caused by parasitic protozoa from the genus of Plasmodium. The protozoans have developed resistance against many of current drugs. It is urgent to find an alternative source of new antimalarial agent. In the effort to discover new antimalarial agents, this research has been conducted on Plectranthus amboinicus. Aims: This study was conducted to evaluate the toxicity and antiplasmodial properties of P. amboinicus. Materials and Methods: Acute oral toxicity dose at 5000 mg/kg was conducted to evaluate the safety of this extract. Twenty mice were divided into control and experimental group. All the mice were observed for signs of toxicity, mortality, weight changes and histopathological changes. Antimalarial activity of different extract doses of 50, 200, 400 and 1000 mg/kg were tested in vivo against Plasmodium berghei infections in mice (five mice for each group) during early, established and residual infections. Results: The acute oral toxicity test revealed that no mortality or evidence of adverse effects was seen in the treated mice. The extract significantly reduced the parasitemia by the 50 (P = 0.000), 200 (P = 0.000) and 400 mg/kg doses (P = 0.000) in the in vivo prophylactic assay. The percentage chemo-suppression was calculated as 83.33% for 50 mg/kg dose, 75.62% for 200 mg/kg dose and 90.74% for 400 mg/kg dose. Body weight of all treated groups; T1, T2, T3 and T4 also showed enhancement after 7 days posttreatment. Statistically no reduction of parasitemia calculated for curative and suppressive test. Conclusion: Thus, this extract may give a promising agent to be used as a prophylactic agent of P. berghei infection. PMID:25276063

  14. Construction of living cellular automata using the Physarum plasmodium

    NASA Astrophysics Data System (ADS)

    Shirakawa, Tomohiro; Sato, Hiroshi; Ishiguro, Shinji

    2015-04-01

    The plasmodium of Physarum polycephalum is a unicellular and multinuclear giant amoeba that has an amorphous cell body. To clearly observe how the plasmodium makes decisions in its motile and exploratory behaviours, we developed a new experimental system to pseudo-discretize the motility of the organism. In our experimental space that has agar surfaces arranged in a two-dimensional lattice, the continuous and omnidirectional movement of the plasmodium was limited to the stepwise one, and the direction of the locomotion was also limited to four neighbours. In such an experimental system, a cellular automata-like system was constructed using the living cell. We further analysed the exploratory behaviours of the plasmodium by duplicating the experimental results in the simulation models of cellular automata. As a result, it was revealed that the behaviours of the plasmodium are not reproduced by only local state transition rules; and for the reproduction, a kind of historical rule setting is needed.

  15. An essential role of the basal body protein SAS-6 in Plasmodium male gamete development and malaria transmission.

    PubMed

    Marques, Sara R; Ramakrishnan, Chandra; Carzaniga, Raffaella; Blagborough, Andrew M; Delves, Michael J; Talman, Arthur M; Sinden, Robert E

    2015-02-01

    Gametocytes are the sole Plasmodium parasite stages that infect mosquitoes; therefore development of functional gametes is required for malaria transmission. Flagellum assembly of the Plasmodium male gamete differs from that of most other eukaryotes in that it is intracytoplasmic but retains a key conserved feature: axonemes assemble from basal bodies. The centriole/basal body protein SAS-6 normally regulates assembly and duplication of these organelles and its depletion causes severe flagellar/ciliary abnormalities in a diverse array of eukaryotes. Since basal body and flagellum assembly are intimately coupled to male gamete development in Plasmodium, we hypothesized that SAS-6 disruption may cause gametogenesis defects and perturb transmission. We show that Plasmodium berghei sas6 knockouts display severely abnormal male gametogenesis presenting reduced basal body numbers, axonemal assembly defects and abnormal nuclear allocation. The defects in gametogenesis reduce fertilization and render Pbsas6 knockouts less infectious to mosquitoes. Additionally, we show that lack of Pbsas6 blocks transmission from mosquito to vertebrate host, revealing an additional yet undefined role in ookinete to sporulating oocysts transition. These findings underscore the vulnerability of the basal body/SAS-6 to malaria transmission blocking interventions.

  16. Simple Molecular Methods for Early Detection of Chloroquine Drug Resistance in Plasmodium vivax and Plasmodium falciparum

    PubMed Central

    Singh, Raksha; Urhehar, Anant Dattatraya

    2016-01-01

    Introduction Malaria is a human disease of which causes high morbidity and mortality. In Plasmodium falciparum malaria, the resistance to antimalarial drugs, especially chloroquine (CQ) is one of the paramount factors contributing to the global increase in morbidity and mortality, due to malaria. Hence, there is a need for detection of chloroquine drug resistance genes i.e., pfcrt-o (Plasmodium falciparum chloroquine resistance transporter-o) and pfmdr-1 (Plasmodium falciparum multidrug resistance-1) of P. falciparum and pvcrt-o (Plasmodium vivax chloroquine resistance transporter-o) and pvmdr-1 (Plasmodium vivax multidrug resistance-1) of P. vivax by using molecular methods to prevent mortality in malarial cases. Aim To standardize chloroquine drug sensitivity testing by molecular method so as to provide reports of chloroquine within 6-8 hours to physicians for better treatment. Materials and Methods This study was conducted over a period of one year from January to December 2014. A Total of 300 blood samples were collected from malaria suspected patient attending MGM Hospital, Kamothe, Navi Mumbai, India. Out of 300 blood samples, 44 were malaria positive as assessed by Thick and Thin blood smear stained, by Leishman’s method and examination with light microscope. Chloroquine drug sensitivity testing was performed using WHO III plate method (micro test). Nested PCR was done for detection of pfcrt-o and pfmdr-1 for P. falciparum and pvcrt-o, pvmdr-1 genes for P. vivax. Results Total 44 samples were included in this study, out of which 22 samples confirmed for Plasmodium falciparum and 22 samples confirmed for Plasmodium vivax. Out of 22 P. falciparum 15 (68.18%) samples were chloroquine resistant. P. vivax showed chloroquine resistance to 5 samples (22.73%) by method similar to WHO III plate method (micro test) and nested PCR. Conclusion Drug resistance testing by molecular methods is useful for early detection of antimalarial drug resistance. pfmdr-1 along with

  17. Simple Molecular Methods for Early Detection of Chloroquine Drug Resistance in Plasmodium vivax and Plasmodium falciparum

    PubMed Central

    Singh, Raksha; Urhehar, Anant Dattatraya

    2016-01-01

    Introduction Malaria is a human disease of which causes high morbidity and mortality. In Plasmodium falciparum malaria, the resistance to antimalarial drugs, especially chloroquine (CQ) is one of the paramount factors contributing to the global increase in morbidity and mortality, due to malaria. Hence, there is a need for detection of chloroquine drug resistance genes i.e., pfcrt-o (Plasmodium falciparum chloroquine resistance transporter-o) and pfmdr-1 (Plasmodium falciparum multidrug resistance-1) of P. falciparum and pvcrt-o (Plasmodium vivax chloroquine resistance transporter-o) and pvmdr-1 (Plasmodium vivax multidrug resistance-1) of P. vivax by using molecular methods to prevent mortality in malarial cases. Aim To standardize chloroquine drug sensitivity testing by molecular method so as to provide reports of chloroquine within 6-8 hours to physicians for better treatment. Materials and Methods This study was conducted over a period of one year from January to December 2014. A Total of 300 blood samples were collected from malaria suspected patient attending MGM Hospital, Kamothe, Navi Mumbai, India. Out of 300 blood samples, 44 were malaria positive as assessed by Thick and Thin blood smear stained, by Leishman’s method and examination with light microscope. Chloroquine drug sensitivity testing was performed using WHO III plate method (micro test). Nested PCR was done for detection of pfcrt-o and pfmdr-1 for P. falciparum and pvcrt-o, pvmdr-1 genes for P. vivax. Results Total 44 samples were included in this study, out of which 22 samples confirmed for Plasmodium falciparum and 22 samples confirmed for Plasmodium vivax. Out of 22 P. falciparum 15 (68.18%) samples were chloroquine resistant. P. vivax showed chloroquine resistance to 5 samples (22.73%) by method similar to WHO III plate method (micro test) and nested PCR. Conclusion Drug resistance testing by molecular methods is useful for early detection of antimalarial drug resistance. pfmdr-1 along with

  18. [Is Plasmodium falciparum, the parasite responsible for tropical malaria, resistant to fansidar?].

    PubMed

    Holzer, B; Keller, H; Frossard, E; Stürchler, D

    1980-03-01

    A world-wide increase of malaria infections is observed. Malaria is imported into Switzerland mainly by tourists and recently by refugees from South East Asia. The strains of P. falciparum resistant to treatment are of increasing importance. A patient with P. falciparum infection from Cambodia is reported, who suffered from three episodes of malaria recrudescence within ten weeks, in spite of adequate therapy with quinine and Fansidar. The definition, the significance and the geographical distribution of resistances and the possible cause for a P. falciparum recrudescence are discussed. For the treatment of repeating recrudescence quinine and Fansidar are recommended, followed by a suppressive Fansidar prophylaxy for 4--8 weeks.

  19. Branched Tricarboxylic Acid Metabolism in Plasmodium falciparum

    PubMed Central

    Olszewski, Kellen L.; Mather, Michael W.; Morrisey, Joanne M.; Garcia, Benjamin A.; Vaidya, Akhil B.; Rabinowitz, Joshua D.; Llinás, Manuel

    2010-01-01

    A central hub of carbon metabolism is the tricarboxylic acid (TCA) cycle1, which serves to connect the processes of glycolysis, gluconeogenesis, respiration, amino acid synthesis and other biosynthetic pathways. The protozoan intracellular malaria parasites (Plasmodium spp.), however, have long been suspected of possessing a significantly streamlined carbon metabolic network in which TCA metabolism plays a minor role2. Blood-stage Plasmodium parasites rely almost entirely on glucose fermentation for energy and consume minimal amounts of oxygen3, yet the parasite genome encodes all of the enzymes necessary for a complete TCA cycle4. By tracing 13C-labeled compounds using mass spectrometry5 we show that TCA metabolism in the human malaria parasite P. falciparum is largely disconnected from glycolysis and is organized along a fundamentally different architecture than the canonical textbook pathway. We find that this pathway is not cyclic but rather a branched structure in which the major carbon sources are the amino acids glutamate and glutamine. As a consequence of this branched architecture, several reactions must run in the reverse of the standard direction thereby generating two-carbon units in the form of acetyl-coenzyme A (acetyl-CoA). We further show that glutamine-derived acetyl-CoA is used for histone acetylation while glucose-derived acetyl-CoA is used to acetylate aminosugars. Thus the parasite has evolved two independent acetyl-CoA-production mechanisms with different biological functions. These results significantly clarify our understanding of the Plasmodium metabolic network and highlight the ability of altered variants of central carbon metabolism to arise in response to unique environments. PMID:20686576

  20. The Glutathione Biosynthetic Pathway of Plasmodium Is Essential for Mosquito Transmission

    PubMed Central

    Vega-Rodríguez, Joel; Janse, Chris J.; Pastrana-Mena, Rebecca; Waters, Andrew P.; Coppens, Isabelle; Rodríguez-Orengo, José F.; Jacobs-Lorena, Marcelo; Serrano, Adelfa E.

    2009-01-01

    Infection of red blood cells (RBC) subjects the malaria parasite to oxidative stress. Therefore, efficient antioxidant and redox systems are required to prevent damage by reactive oxygen species. Plasmodium spp. have thioredoxin and glutathione (GSH) systems that are thought to play a major role as antioxidants during blood stage infection. In this report, we analyzed a critical component of the GSH biosynthesis pathway using reverse genetics. Plasmodium berghei parasites lacking expression of gamma-glutamylcysteine synthetase (γ-GCS), the rate limiting enzyme in de novo synthesis of GSH, were generated through targeted gene disruption thus demonstrating, quite unexpectedly, that γ-GCS is not essential for blood stage development. Despite a significant reduction in GSH levels, blood stage forms of pbggcs− parasites showed only a defect in growth as compared to wild type. In contrast, a dramatic effect on development of the parasites in the mosquito was observed. Infection of mosquitoes with pbggcs− parasites resulted in reduced numbers of stunted oocysts that did not produce sporozoites. These results have important implications for the design of drugs aiming at interfering with the GSH redox-system in blood stages and demonstrate that de novo synthesis of GSH is pivotal for development of Plasmodium in the mosquito. PMID:19229315

  1. No evidence for ape Plasmodium infections in humans in Gabon.

    PubMed

    Délicat-Loembet, Lucresse; Rougeron, Virginie; Ollomo, Benjamin; Arnathau, Céline; Roche, Benjamin; Elguero, Eric; Moukodoum, Nancy Diamella; Okougha, Alain-Prince; Mve Ondo, Bertrand; Boundenga, Larson; Houzé, Sandrine; Galan, Maxime; Nkoghé, Dieudonné; Leroy, Eric M; Durand, Patrick; Paupy, Christophe; Renaud, François; Prugnolle, Franck

    2015-01-01

    African great apes are naturally infected by a multitude of Plasmodium species most of them recently discovered, among which several are closely related to human malaria agents. However, it is still unknown whether these animals can serve as source of infections for humans living in their vicinity. To evaluate this possibility, we analysed the nature of Plasmodium infections from a bank of 4281 human blood samples collected in 210 villages of Gabon, Central Africa. Among them, 2255 were detected positive to Plasmodium using molecular methods (Plasmodium Cytochrome b amplification). A high throughput sequencing technology (454 GS-FLX Titanium technology, Roche) was then used to identify the Plasmodium species present within each positive sample. Overall, we identified with confidence only three species infecting humans in Gabon: P. falciparum, P. malariae and P. ovale. None of the species known to infect non-human primates in Central Africa was found. Our study shows that ape Plasmodium parasites of the subgenus Laverania do not constitute a frequent source of infection for humans. It also suggests that some strong host genetic barriers must exist to prevent the cross species transmission of ape Plasmodium in a context of ever increasing contacts between humans and wildlife.

  2. No Evidence for Ape Plasmodium Infections in Humans in Gabon

    PubMed Central

    Ollomo, Benjamin; Arnathau, Céline; Roche, Benjamin; Elguero, Eric; Moukodoum, Nancy Diamella; Okougha, Alain-Prince; Mve Ondo, Bertrand; Boundenga, Larson; Houzé, Sandrine; Galan, Maxime; Nkoghé, Dieudonné; Leroy, Eric M.; Durand, Patrick; Paupy, Christophe; Renaud, François; Prugnolle, Franck

    2015-01-01

    African great apes are naturally infected by a multitude of Plasmodium species most of them recently discovered, among which several are closely related to human malaria agents. However, it is still unknown whether these animals can serve as source of infections for humans living in their vicinity. To evaluate this possibility, we analysed the nature of Plasmodium infections from a bank of 4281 human blood samples collected in 210 villages of Gabon, Central Africa. Among them, 2255 were detected positive to Plasmodium using molecular methods (Plasmodium Cytochrome b amplification). A high throughput sequencing technology (454 GS-FLX Titanium technology, Roche) was then used to identify the Plasmodium species present within each positive sample. Overall, we identified with confidence only three species infecting humans in Gabon: P. falciparum, P. malariae and P. ovale. None of the species known to infect non-human primates in Central Africa was found. Our study shows that ape Plasmodium parasites of the subgenus Laverania do not constitute a frequent source of infection for humans. It also suggests that some strong host genetic barriers must exist to prevent the cross species transmission of ape Plasmodium in a context of ever increasing contacts between humans and wildlife. PMID:26039338

  3. Use of molecular beacon probes for real-time PCR detection of Plasmodium falciparum and other plasmodium species in peripheral blood specimens.

    PubMed

    Elsayed, Sameer; Plewes, Katherine; Church, Deirdre; Chow, Barbara; Zhang, Kunyan

    2006-02-01

    We describe the development and evaluation of a novel pair of real-time, fluorescence-based PCR assays using molecular beacon probes for rapid, sensitive, and specific detection and quantification of Plasmodium falciparum and other Plasmodium species organisms.

  4. Plasmodium ovale curtisi and Plasmodium ovale wallikeri in North-West Ethiopia

    PubMed Central

    2013-01-01

    Background In Ethiopia Plasmodium falciparum and Plasmodium vivax are the dominant species accounting for roughly 60 and 40% of malaria cases, respectively. Recently a major shift from P. falciparum to P. vivax has been observed in various parts of the country but the epidemiology of the other human malaria species, Plasmodium ovale spp. and Plasmodium malariae remains poorly understood. The aim of this study was to assess P. ovale curtisi and wallikeri infection in north-west Ethiopia by using microscopy and nested PCR. Methods A health institution-based survey using non-probability sampling techniques was conducted at Maksegnet, Enfranze and Kola Diba health centres and Metema hospital in North Gondar. Three-hundred patients with signs and symptoms consistent with malaria were included in this study and capillary blood was collected for microscopic examination and molecular analysis of Plasmodium species. Samples were collected on Whatman 903 filter papers, stored in small plastic bags with desiccant and transported to Vienna (Austria) for molecular analysis. Data from study participants were entered and analysed by SPSS 20 software. Results Out of 300 study participants (167 males and 133 females), 184 samples were classified positive for malaria (133 P. falciparum and 51 P. vivax) by microscopy. By species-specific PCR 233 Plasmodium spp (95% CI: 72.6-82) were detected and the majority 155 (66.5%, 95% CI: 60.2-72.3) were P. falciparum followed by P. vivax 69 (29.6%, 95% CI; 24.1-35.8) and 9 (3.9%, 95% CI: 2-7.2) samples were positive for P. ovale. Seven of P. ovale parasites were confirmed as P. ovale wallikeri and two were confirmed as P. ovale curtisi. None of the samples tested positive for P. malariae. During microscopic examination there were high (16.3%) false negative reports and all mixed infections and P. ovale cases were missed or misclassified. Conclusion This study indicates that P. ovale malaria is under-reported in Ethiopia and provides the first

  5. Marine organism sulfated polysaccharides exhibiting significant antimalarial activity and inhibition of red blood cell invasion by Plasmodium.

    PubMed

    Marques, Joana; Vilanova, Eduardo; Mourão, Paulo A S; Fernàndez-Busquets, Xavier

    2016-01-01

    The antimalarial activity of heparin, against which there are no resistances known, has not been therapeutically exploited due to its potent anticoagulating activity. Here, we have explored the antiplasmodial capacity of heparin-like sulfated polysaccharides from the sea cucumbers Ludwigothurea grisea and Isostichopus badionotus, from the red alga Botryocladia occidentalis, and from the marine sponge Desmapsamma anchorata. In vitro experiments demonstrated for most compounds significant inhibition of Plasmodium falciparum growth at low-anticoagulant concentrations. This activity was found to operate through inhibition of erythrocyte invasion by Plasmodium, likely mediated by a coating of the parasite similar to that observed for heparin. In vivo four-day suppressive tests showed that several of the sulfated polysaccharides improved the survival of Plasmodium yoelii-infected mice. In one animal treated with I. badionotus fucan parasitemia was reduced from 10.4% to undetectable levels, and Western blot analysis revealed the presence of antibodies against P. yoelii antigens in its plasma. The retarded invasion mediated by sulfated polysaccharides, and the ensuing prolonged exposure of Plasmodium to the immune system, can be explored for the design of new therapeutic approaches against malaria where heparin-related polysaccharides of low anticoagulating activity could play a dual role as drugs and as potentiators of immune responses. PMID:27071342

  6. Marine organism sulfated polysaccharides exhibiting significant antimalarial activity and inhibition of red blood cell invasion by Plasmodium

    PubMed Central

    Marques, Joana; Vilanova, Eduardo; Mourão, Paulo A. S.; Fernàndez-Busquets, Xavier

    2016-01-01

    The antimalarial activity of heparin, against which there are no resistances known, has not been therapeutically exploited due to its potent anticoagulating activity. Here, we have explored the antiplasmodial capacity of heparin-like sulfated polysaccharides from the sea cucumbers Ludwigothurea grisea and Isostichopus badionotus, from the red alga Botryocladia occidentalis, and from the marine sponge Desmapsamma anchorata. In vitro experiments demonstrated for most compounds significant inhibition of Plasmodium falciparum growth at low-anticoagulant concentrations. This activity was found to operate through inhibition of erythrocyte invasion by Plasmodium, likely mediated by a coating of the parasite similar to that observed for heparin. In vivo four-day suppressive tests showed that several of the sulfated polysaccharides improved the survival of Plasmodium yoelii-infected mice. In one animal treated with I. badionotus fucan parasitemia was reduced from 10.4% to undetectable levels, and Western blot analysis revealed the presence of antibodies against P. yoelii antigens in its plasma. The retarded invasion mediated by sulfated polysaccharides, and the ensuing prolonged exposure of Plasmodium to the immune system, can be explored for the design of new therapeutic approaches against malaria where heparin-related polysaccharides of low anticoagulating activity could play a dual role as drugs and as potentiators of immune responses. PMID:27071342

  7. Human Infections and Detection of Plasmodium knowlesi

    PubMed Central

    Daneshvar, Cyrus

    2013-01-01

    SUMMARY Plasmodium knowlesi is a malaria parasite that is found in nature in long-tailed and pig-tailed macaques. Naturally acquired human infections were thought to be extremely rare until a large focus of human infections was reported in 2004 in Sarawak, Malaysian Borneo. Human infections have since been described throughout Southeast Asia, and P. knowlesi is now recognized as the fifth species of Plasmodium causing malaria in humans. The molecular, entomological, and epidemiological data indicate that human infections with P. knowlesi are not newly emergent and that knowlesi malaria is primarily a zoonosis. Human infections were undiagnosed until molecular detection methods that could distinguish P. knowlesi from the morphologically similar human malaria parasite P. malariae became available. P. knowlesi infections cause a spectrum of disease and are potentially fatal, but if detected early enough, infections in humans are readily treatable. In this review on knowlesi malaria, we describe the early studies on P. knowlesi and focus on the epidemiology, diagnosis, clinical aspects, and treatment of knowlesi malaria. We also discuss the gaps in our knowledge and the challenges that lie ahead in studying the epidemiology and pathogenesis of knowlesi malaria and in the prevention and control of this zoonotic infection. PMID:23554413

  8. The sex ratio of Plasmodium gametocytes.

    PubMed

    Schall, J J

    1989-06-01

    Sex ratio theory usually predicts an equilibrium sex ratio and equal proportions of males and females in a population, including the progenitors of the reproductive cells of protozoans. This proposal was tested with three species of malarial parasites of lizards, Plasmodium mexicanum of the western fence lizard, and P. agamae and P. giganteum of the African rainbow lizard, using single samples from naturally infected lizards, repeated samples from free-ranging lizards (P. mexicanum only), and repeated samples from laboratory maintained animals. Macrogametocytes were usually more abundant than microgametocytes, and were slightly larger, revealing a typically greater investment of resources by the progenitors of female reproductive cells. However, the proportion of microgametocytes varied among the three species and among infections within each species of Plasmodium. The sex ratio of gametocytes often remained constant within infections followed over time even if the absolute number of gametocytes was changing. However, the equilibrium sex ratio of gametocytes varied among those infections that had an unchanging microgametocyte proportion. Thus, although an equilibrium sex ratio apparently occurs for most infections, there appears to be no characteristic proportion of microgametocytes for any of the species. Potential explanations for this conflict with theory are presented. PMID:2771445

  9. Management of relapsing Plasmodium vivax malaria

    PubMed Central

    Chu, Cindy S; White, Nicholas J

    2016-01-01

    ABSTRACT Introduction: Relapses are important contributors to illness and morbidity in Plasmodium vivax and P. ovale infections. Relapse prevention (radical cure) with primaquine is required for optimal management, control and ultimately elimination of Plasmodium vivax malaria. A review was conducted with publications in English, French, Portuguese and Spanish using the search terms ‘P. vivax’ and ‘relapse’. Areas covered: Hypnozoites causing relapses may be activated weeks or months after initial infection. Incidence and temporal patterns of relapse varies geographically. Relapses derive from parasites either genetically similar or different from the primary infection indicating that some derive from previous infections. Malaria illness itself may activate relapse. Primaquine is the only widely available treatment for radical cure. However, it is often not given because of uncertainty over the risks of primaquine induced haemolysis when G6PD deficiency testing is unavailable. Recommended dosing of primaquine for radical cure in East Asia and Oceania is 0.5 mg base/kg/day and elsewhere is 0.25 mg base/kg/day. Alternative treatments are under investigation. Expert commentary: Geographic heterogeneity in relapse patterns and chloroquine susceptibility of P. vivax, and G6PD deficiency epidemiology mean that radical treatment should be given much more than it is today. G6PD testing should be made widely available so primaquine can be given more safely. PMID:27530139

  10. Chloroquine resistance of Plasmodium berghei: biochemical basis and countermeasures*

    PubMed Central

    Salganik, R. I.; Pankova, T. G.; Chekhonadskikh, T. V.; Igonina, T. M.

    1987-01-01

    Microsomal monooxygenases, enzymes that metabolize xenobiotics, may be responsible for the chloroquine resistance of malarial parasites. Plasmodium cells contain cytochrome P-450 and exhibit aryl hydrocarbon hydroxylase and aminopyrine N-dimethylase activity, two monooxygenases that inactivate chloroquine. The activities of these monooxygenases are considerably higher in chloroquine-resistant strains of Plasmodium berghei than in the chloroquine-sensitive strain of the parasite. Inhibitors of microsomal monooxygenases have the potential to overcome the chloroquine resistance of Plasmodium spp., and, of those inhibitors tested, the copper-lysine complex, copper(lysine)2, was the most effective. PMID:3117393

  11. Plasmodium falciparum full life cycle and Plasmodium ovale liver stages in humanized mice

    PubMed Central

    Soulard, Valérie; Bosson-Vanga, Henriette; Lorthiois, Audrey; Roucher, Clémentine; Franetich, Jean- François; Zanghi, Gigliola; Bordessoulles, Mallaury; Tefit, Maurel; Thellier, Marc; Morosan, Serban; Le Naour, Gilles; Capron, Frédérique; Suemizu, Hiroshi; Snounou, Georges; Moreno-Sabater, Alicia; Mazier, Dominique

    2015-01-01

    Experimental studies of Plasmodium parasites that infect humans are restricted by their host specificity. Humanized mice offer a means to overcome this and further provide the opportunity to observe the parasites in vivo. Here we improve on previous protocols to achieve efficient double engraftment of TK-NOG mice by human primary hepatocytes and red blood cells. Thus, we obtain the complete hepatic development of P. falciparum, the transition to the erythrocytic stages, their subsequent multiplication, and the appearance of mature gametocytes over an extended period of observation. Furthermore, using sporozoites derived from two P. ovale-infected patients, we show that human hepatocytes engrafted in TK-NOG mice sustain maturation of the liver stages, and the presence of late-developing schizonts indicate the eventual activation of quiescent parasites. Thus, TK-NOG mice are highly suited for in vivo observations on the Plasmodium species of humans. PMID:26205537

  12. Population genetics of Plasmodium falciparum and Plasmodium vivax and asymptomatic malaria in Temotu Province, Solomon Islands

    PubMed Central

    2013-01-01

    Background Temotu Province, Solomon Islands is progressing toward malaria elimination. A baseline survey conducted in 2008 showed that most Plasmodium infections in the province were of low parasite density and asymptomatic infections. To better understand mechanisms underlying these malaria transmission characteristics genetic diversity and relationships among Plasmodium falciparum and Plasmodium vivax populations in the province were examined. Methods Forty-five P. falciparum and 67 P. vivax samples collected in the 2008 baseline survey were successfully genotyped using eight P. falciparum and seven P. vivax microsatellite markers. Genetic diversity, relationships and distribution of both P. falciparum and P. vivax populations were analysed. Results Plasmodium falciparum population exhibited low diversity with 19 haplotypes identified and had closely related clusters indicating clonal expansion. Interestingly, a dominant haplotype was significantly associated with fever and high parasite density. In contrast, the P. vivax population was highly diverse with 58 haplotypes identified that were not closely related. Parasite populations between different islands in the province showed low genetic differentiation. Conclusion The low diversity and clonal population of P. falciparum population may partially account for clinical immunity developed against illness. However, it is possible that importation of a new P. falciparum strain was the major cause of illness. High diversity in P. vivax population and low relatedness between strains suggested clinical immunity to P. vivax may be maintained by different mechanisms. The genetic diversity, population structure and distribution of strains indicate that transmission of P. falciparum was low, but that of P. vivax was still high in 2008. These data will be useful for assessing changes in malaria transmission resulting from interventions. PMID:24261646

  13. Colombian Anopheles triannulatus (Diptera: Culicidae) Naturally Infected with Plasmodium spp.

    PubMed Central

    Rosero, Doris A.; Naranjo-Diaz, Nelson; Alvarez, Natalí; Cienfuegos, Astrid V.; Luckhart, Shirley

    2013-01-01

    The role of Anopheles triannulatus as a local vector has not yet been defined for malaria-endemic regions of Colombia. Therefore, the aim of this work was to detect An. triannulatus naturally infected with Plasmodium spp., as an approximation to determining its importance as malaria vector in the country. A total of 510 An. triannulatus were collected in six malaria-endemic localities of NW and SE Colombia from January 2009 to March 2011. In the NW, two specimens were naturally infected; one with Plasmodium vivax VK247, collected biting on humans and the other with Plasmodium falciparum, collected resting on cattle. In the SE, two specimens were positive for P. falciparum. Although these results show An. triannulatus naturally infected with Plasmodium, further studies are recommended to demonstrate the epidemiological importance of this species in malaria-endemic regions of Colombia. PMID:27335865

  14. Plasmodium species: master renovators of their host cells.

    PubMed

    de Koning-Ward, Tania F; Dixon, Matthew W A; Tilley, Leann; Gilson, Paul R

    2016-08-01

    Plasmodium parasites, the causative agents of malaria, have developed elaborate strategies that they use to survive and thrive within different intracellular environments. During the blood stage of infection, the parasite is a master renovator of its erythrocyte host cell, and the changes in cell morphology and function that are induced by the parasite promote survival and contribute to the pathogenesis of severe malaria. In this Review, we discuss how Plasmodium parasites use the protein trafficking motif Plasmodium export element (PEXEL), protease-mediated polypeptide processing, a novel translocon termed the Plasmodium translocon of exported proteins (PTEX) and exomembranous structures to export hundreds of proteins to discrete subcellular locations in the host erythrocytes, which enables the parasite to gain access to vital nutrients and to evade the immune defence mechanisms of the host.

  15. Repeated Plasmodium vivax malaria relapses in a Peruvian sailor.

    PubMed

    McFarland, Adam P; Sanchez, Juan F; Mercado, Alejandro; Ventocilla, Julio A; Cavalcanti, Sofia; Gonzalez, Sofia; Lescano, Andres G

    2015-01-01

    Two Plasmodium vivax recurrences in a Peruvian sailor with weight above the 60 kg (cap for primaquine dosage) highlight the importance of adequate radical cure weight dosage for patient treatment and control efforts, particularly within the military. PMID:26620122

  16. Repeated Plasmodium vivax malaria relapses in a Peruvian sailor.

    PubMed

    McFarland, Adam P; Sanchez, Juan F; Mercado, Alejandro; Ventocilla, Julio A; Cavalcanti, Sofia; Gonzalez, Sofia; Lescano, Andres G

    2015-12-01

    Two Plasmodium vivax recurrences in a Peruvian sailor with weight above the 60 kg (cap for primaquine dosage) highlight the importance of adequate radical cure weight dosage for patient treatment and control efforts, particularly within the military.

  17. The kinetics of antibody binding to Plasmodium falciparum VAR2CSA PfEMP1 antigen and modelling of PfEMP1 antigen packing on the membrane knobs

    PubMed Central

    2010-01-01

    Background Infected humans make protective antibody responses to the PfEMP1 adhesion antigens exported by Plasmodium falciparum parasites to the erythrocyte membrane, but little is known about the kinetics of this antibody-receptor binding reaction or how the topology of PfEMP1 on the parasitized erythrocyte membrane influences antibody association with, and dissociation from, its antigenic target. Methods A Quartz Crystal Microbalance biosensor was used to measure the association and dissociation kinetics of VAR2CSA PfEMP1 binding to human monoclonal antibodies. Immuno-fluorescence microscopy was used to visualize antibody-mediated adhesion between the surfaces of live infected erythrocytes and atomic force microscopy was used to obtain higher resolution images of the membrane knobs on the infected erythrocyte to estimate knob surface areas and model VAR2CSA packing density on the knob. Results Kinetic analysis indicates that antibody dissociation from the VAR2CSA PfEMP1 antigen is extremely slow when there is a high avidity interaction. High avidity binding to PfEMP1 antigens on the surface of P. falciparum-infected erythrocytes in turn requires bivalent cross-linking of epitopes positioned within the distance that can be bridged by antibody. Calculations of the surface area of the knobs and the possible densities of PfEMP1 packing on the knobs indicate that high-avidity cross-linking antibody reactions are constrained by the architecture of the knobs and the large size of PfEMP1 molecules. Conclusions High avidity is required to achieve the strongest binding to VAR2CSA PfEMP1, but the structures that display PfEMP1 also tend to inhibit cross-linking between PfEMP1 antigens, by holding many binding epitopes at distances beyond the 15-18 nm sweep radius of an antibody. The large size of PfEMP1 will also constrain intra-knob cross-linking interactions. This analysis indicates that effective vaccines targeting the parasite's vulnerable adhesion receptors should

  18. Rheopathologic Consequence of Plasmodium vivax Rosette Formation.

    PubMed

    Zhang, Rou; Lee, Wenn-Chyau; Lau, Yee-Ling; Albrecht, Letusa; Lopes, Stefanie C P; Costa, Fabio T M; Suwanarusk, Rossarin; Nosten, Francois; Cooke, Brian M; Rénia, Laurent; Russell, Bruce

    2016-08-01

    Malaria parasites dramatically alter the rheological properties of infected red blood cells. In the case of Plasmodium vivax, the parasite rapidly decreases the shear elastic modulus of the invaded RBC, enabling it to avoid splenic clearance. This study highlights correlation between rosette formation and altered membrane deformability of P. vivax-infected erythrocytes, where the rosette-forming infected erythrocytes are significantly more rigid than their non-rosetting counterparts. The adhesion of normocytes to the PvIRBC is strong (mean binding force of 440pN) resulting in stable rosette formation even under high physiological shear flow stress. Rosetting may contribute to the sequestration of PvIRBC schizonts in the host microvasculature or spleen. PMID:27509168

  19. Rheopathologic Consequence of Plasmodium vivax Rosette Formation

    PubMed Central

    Lau, Yee-Ling; Albrecht, Letusa; Lopes, Stefanie C. P.; Costa, Fabio T. M.; Suwanarusk, Rossarin; Nosten, Francois; Cooke, Brian M.; Rénia, Laurent; Russell, Bruce

    2016-01-01

    Malaria parasites dramatically alter the rheological properties of infected red blood cells. In the case of Plasmodium vivax, the parasite rapidly decreases the shear elastic modulus of the invaded RBC, enabling it to avoid splenic clearance. This study highlights correlation between rosette formation and altered membrane deformability of P. vivax-infected erythrocytes, where the rosette-forming infected erythrocytes are significantly more rigid than their non-rosetting counterparts. The adhesion of normocytes to the PvIRBC is strong (mean binding force of 440pN) resulting in stable rosette formation even under high physiological shear flow stress. Rosetting may contribute to the sequestration of PvIRBC schizonts in the host microvasculature or spleen. PMID:27509168

  20. The paradoxical population genetics of Plasmodium falciparum.

    PubMed

    Hartl, Daniel L; Volkman, Sarah K; Nielsen, Kaare M; Barry, Alyssa E; Day, Karen P; Wirth, Dyann F; Winzeler, Elizabeth A

    2002-06-01

    Among the leading causes of death in African children is cerebral malaria caused by the parasitic protozoan Plasmodium falciparum. Endemic forms of this disease are thought to have originated in central Africa 5000-10000 years ago, coincident with the innovation of slash-and-burn agriculture and the diversification of the Anopheles gambiae complex of mosquito vectors. Population genetic studies of P. falciparum have yielded conflicting results. Some evidence suggests that today's population includes multiple ancient lineages pre-dating human speciation. Other evidence suggests that today's population derives from only one, or a small number, of these ancient lineages. Resolution of this issue is important for the evaluation of the long-term efficacy of drug and immunological control strategies. PMID:12036741

  1. Development of vaccines for Plasmodium vivax malaria.

    PubMed

    Mueller, Ivo; Shakri, Ahmad Rushdi; Chitnis, Chetan E

    2015-12-22

    Plasmodium vivax continues to cause significant morbidity outside Africa with more than 50% of malaria cases in many parts of South and South-east Asia, Pacific islands, Central and South America being attributed to P. vivax infections. The unique biology of P. vivax, including its ability to form latent hypnozoites that emerge months to years later to cause blood stage infections, early appearance of gametocytes before clinical symptoms are apparent and a shorter development cycle in the vector makes elimination of P. vivax using standard control tools difficult. The availability of an effective vaccine that provides protection and prevents transmission would be a valuable tool in efforts to eliminate P. vivax. Here, we review the latest developments related to P. vivax malaria vaccines and discuss the challenges as well as directions toward the goal of developing highly efficacious vaccines against P. vivax malaria.

  2. Plasmodium vivax genetic diversity: microsatellite length matters.

    PubMed

    Russell, Bruce; Suwanarusk, Rossarin; Lek-Uthai, Usa

    2006-09-01

    The Plasmodium vivax genome is very diverse but has a relatively low abundance of microsatellites. Leclerc et al. had shown that these di-nucleotide repeats have a low level of polymorphism, suggesting a recent bottleneck event in the evolutionary history of P. vivax. By contrast, in a recent paper, Imwong et al. show that there is a very high level of microsatellite diversity. The difference in these results is probably due to the set array lengths chosen by each group. Longer arrays are more diverse than are shorter ones because slippage mutations become exponentially more common with an increase in array length. These studies highlight the need to consider carefully the application and design of studies involving microsatellites.

  3. The paradoxical population genetics of Plasmodium falciparum.

    PubMed

    Hartl, Daniel L; Volkman, Sarah K; Nielsen, Kaare M; Barry, Alyssa E; Day, Karen P; Wirth, Dyann F; Winzeler, Elizabeth A

    2002-06-01

    Among the leading causes of death in African children is cerebral malaria caused by the parasitic protozoan Plasmodium falciparum. Endemic forms of this disease are thought to have originated in central Africa 5000-10000 years ago, coincident with the innovation of slash-and-burn agriculture and the diversification of the Anopheles gambiae complex of mosquito vectors. Population genetic studies of P. falciparum have yielded conflicting results. Some evidence suggests that today's population includes multiple ancient lineages pre-dating human speciation. Other evidence suggests that today's population derives from only one, or a small number, of these ancient lineages. Resolution of this issue is important for the evaluation of the long-term efficacy of drug and immunological control strategies.

  4. Plasmodium malariae blood-stage dynamics.

    PubMed

    McKenzie, F E; Jeffery, G M; Collins, W E

    2001-06-01

    We examine the dynamics of parasitemia, fever, and gametocytemia reflected in the preintervention charts of 180 malaria-naive U.S. neurosyphilis patients infected with the USPHS strain of Plasmodium malariae, for malariatherapy, focusing on the 84 charts for which more than 35 days of patency preceded intervention and daily records encompassed 92% or more of the duration of each infection. Inoculum size did not influence any outcome variable. Fevers (days with temperatures > or =101 F) followed patterns that fit recognized brood structures more often than did our approximations of merogony cycles (via local peaks in parasitemia), but neither closely fit textbook quartan patterns. There were no discernable patterns in gametocytemia. Successful transmission to mosquitoes increased following subcurative drug treatment but did not depend on detectable gametocytemia. PMID:11426728

  5. The effects of urbanization on global Plasmodium vivax malaria transmission

    PubMed Central

    2012-01-01

    Background Many recent studies have examined the impact of urbanization on Plasmodium falciparum malaria endemicity and found a general trend of reduced transmission in urban areas. However, none has examined the effect of urbanization on Plasmodium vivax malaria, which is the most widely distributed malaria species and can also cause severe clinical syndromes in humans. In this study, a set of 10,003 community-based P. vivax parasite rate (PvPR) surveys are used to explore the relationships between PvPR in urban and rural settings. Methods The PvPR surveys were overlaid onto a map of global urban extents to derive an urban/rural assignment. The differences in PvPR values between urban and rural areas were then examined. Groups of PvPR surveys inside individual city extents (urban) and surrounding areas (rural) were identified to examine the local variations in PvPR values. Finally, the relationships of PvPR between urban and rural areas within the ranges of 41 dominant Anopheles vectors were examined. Results Significantly higher PvPR values in rural areas were found globally. The relationship was consistent at continental scales when focusing on Africa and Asia only, but in the Americas, significantly lower values of PvPR in rural areas were found, though the numbers of surveys were small. Moreover, except for the countries in the Americas, the same trends were found at national scales in African and Asian countries, with significantly lower values of PvPR in urban areas. However, the patterns at city scales among 20 specific cities where sufficient data were available were less clear, with seven cities having significantly lower PvPR values in urban areas and two cities showing significantly lower PvPR in rural areas. The urban–rural PvPR differences within the ranges of the dominant Anopheles vectors were generally, in agreement with the regional patterns found. Conclusions Except for the Americas, the patterns of significantly lower P. vivax transmission in

  6. Studies on the effects of sida acuta and vetiveria zizanioides against the malarial vector, anopheles stephensi and malarial parasite, plasmodium berghei

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Methanolic extracts of Sida acuta and Vetiveria zizanioides leaves and root were studied for toxicity to Anopheles stephensi mosquitoes and to the malaria parasite Plasmodium berghei in mice. The extracts reduced parasitemia levels in mice by 17-69%, depending on extract concentration. Median le...

  7. Large-scale growth of the Plasmodium falciparum malaria parasite in a wave bioreactor.

    PubMed

    Dalton, John P; Demanga, Corine G; Reiling, Sarah J; Wunderlich, Juliane; Eng, Jenny W L; Rohrbach, Petra

    2012-01-01

    We describe methods for the large-scale in vitro culturing of synchronous and asynchronous blood-stage Plasmodium falciparum parasites in sterile disposable plastic bioreactors controlled by wave-induced motion (wave bioreactor). These cultures perform better than static flask cultures in terms of preserving parasite cell cycle synchronicity and reducing the number of multiple-infected erythrocytes. The straight-forward methods described here will facilitate the large scale production of malaria parasites for antigen and organelle isolation and characterisation, for the high throughput screening of compound libraries with whole cells or extracts, and the development of live- or whole-cell malaria vaccines under good manufacturing practice compliant standards.

  8. Plasmodium yoelii: induction of attenuated mutants by irradiation

    SciTech Connect

    Waki, S.; Yonome, I.; Suzuki, M.

    1986-12-01

    When erythrocytic forms of Plasmodium yoelii nigeriensis, which is invariably fatal in mice, were exposed to X rays, the dose to reduce surviving parasites to one millionth was 100 gray (10 Krad). A suspension of 5 X 10(6) per ml of parasitized erythrocyte was irradiated at 100 gray, and 0.2 ml aliquots were inoculated into 22 mice. Eleven mice showed patent parasitemia, and in these the growth curves were less steep than that found in nonirradiated parasites. The infections of 8 mice of the 11 were self-resolving, and the attenuated feature of the parasites maintained following a limited number of blood passages. The parasites were slowly growing even in nude mice and cause self-resolving infections in intact mice. BALB/c mice immunized with the attenuated parasites were protected against subsequent challenge infections with the original virulent erythrocytic and sporogonic forms. These findings indicate that attenuated mutants of malaria parasites can be readily induced by this method.

  9. An outbreak of Plasmodium falciparum malaria in the Torres Strait.

    PubMed

    Preston-Thomas, Annie; Gair, Richard W; Hosking, Kelly A; Devine, Gregor J; Donohue, Steven D

    2012-06-01

    This report describes the largest outbreak of Plasmodium falciparum malaria in the Torres Strait for more than 25 years. It details factors that may have contributed to the outbreak, the public health response and implications for the broader region. Eight cases of locally-acquired falciparum malaria occurred on Saibai and Dauan islands during March and April 2011. Including imports, there were 17 P. falciparum notifications between February and May 2011. Three cases of pure P. vivax malaria that might have been locally acquired have been omitted from this report. Malaria is endemic on the nearby coast of Papua New Guinea (PNG), and regularly imported to the Torres Strait where a competent vector exists in sufficient numbers to transmit the disease to the local population. The most common malaria vectors in northern Australia and Torres Strait are the Anopheles farauti complex. Factors contributing to the outbreak may include an increase in travel between the outer islands and PNG, inadequate local vector control and late or missed diagnoses of malaria. Outbreak management involved intensive case finding and treatment, vector control and health promotion. Reducing the risk of future outbreaks requires studies of vector behaviour, ecology and management, health promotion, improvements to protective infrastructure, and clinical guideline revision. Further malaria outbreaks are likely in the Torres Strait and elsewhere in northern Australia. It is important to maintain awareness and be prepared to respond rapidly. PMID:23186217

  10. Rediscovery and redescription of Plasmodium pifanoi and description of two additional Plasmodium parasites of Venezuelan lizards.

    PubMed

    Telford, Sam R; Telford, Sam R

    2003-04-01

    Plasmodium pifanoi Scorza and Dagert B., known only from the type host, Ameiva ameiva, is redescribed from Kentropyx calcarata collected in Territorio Amazonas, Venezuela. Schizonts, 6.2 x 4.5 (4-8 x 3-6), produce on average 11.9 (7-16) merozoites. Gametocytes average 12.4 x 6.0 (8-16 x 4-10), with length x width (LW) 72.9 (52-112) and L/W 2.18 (1.1-3.3), and always contain 1-5 prominent vacuoles. Macrogametocytes in active infection are longer than microgametocytes, with greater LW, but gametocytes in chronic infection are not sexually dimorphic in dimension and are slightly smaller. Two additional malarial parasites are described from K. calcarata. Plasmodium lepidoptiformis has small schizonts, 4.6 x 3.2 (3-6 x 2.5-3), that produce 5.1 (4-8) merozoites and commonly resemble a butterfly in appearance. Gametocytes are elongate, 9.0 x 4.3 (7-10 x 3-6), with LW 38.3 (24-51) and L/W 2.2 (1.3-3.3), and sexually dimorphic, with macrogametocytes longer than microgametocytes, with greater LW. Plasmodium minasense calcaratae is characterized by very small, usually fan-shaped, schizonts. 3.4 x 2.6 (2.5-4.5 x 2.0-3.0), that produce 3.9 (3-4) merozoites. Gametocytes are spherical or ovoid, 6.7 x 5.0 (4.5-9.0 x 3.0-7.0), with LW 33.7 (15-54) and L/W 1.4 (1.0-2.3), with no sexual dimorphism in dimensions. PMID:12760655

  11. Dimorphism in genes encoding sexual-stage proteins of Plasmodium ovale curtisi and Plasmodium ovale wallikeri☆

    PubMed Central

    Oguike, Mary C.; Sutherland, Colin J.

    2015-01-01

    Plasmodium ovale curtisi and Plasmodium ovale wallikeri are distinct species of malaria parasite which are sympatric throughout the tropics, except for the Americas. Despite this complete overlap in geographic range, these two species do not recombine. Although morphologically very similar, the two taxa must possess distinct characters which prevent recombination between them. We hypothesised that proteins required for sexual reproduction have sufficiently diverged between the two species to prevent recombination in any mosquito blood meal in which gametocytes of both species are ingested. In order to investigate possible barriers to inter-species mating between P. ovale curtisi and P. ovale wallikeri, homologues of genes encoding sexual stage proteins in other plasmodia were identified and compared between the two species. Database searches with motifs for 6-cysteine, Limulus Coagulation factor C domain-containing proteins and other relevant sexual stage proteins in the genus Plasmodium were performed in the available P. ovale curtisi partial genome database (Wellcome Trust Sanger Institute, UK). Sequence fragments obtained were used as the basis for PCR walking along each gene of interest in reference isolates of both P. ovale curtisi and P. ovale wallikeri. Sequence alignment of the homologues of each gene in each species showed complete dimorphism across all isolates. In conclusion, substantial divergence between sexual stage proteins in the two P. ovale spp. was observed, providing further evidence that these do not recombine in nature. Incompatibility of proteins involved in sexual development and fertilisation thus remains a plausible explanation for the observed lack of natural recombination between P. ovale curtisi and P. ovale wallikeri. PMID:25817462

  12. Dimorphism in genes encoding sexual-stage proteins of Plasmodium ovale curtisi and Plasmodium ovale wallikeri.

    PubMed

    Oguike, Mary C; Sutherland, Colin J

    2015-06-01

    Plasmodium ovale curtisi and Plasmodium ovale wallikeri are distinct species of malaria parasite which are sympatric throughout the tropics, except for the Americas. Despite this complete overlap in geographic range, these two species do not recombine. Although morphologically very similar, the two taxa must possess distinct characters which prevent recombination between them. We hypothesised that proteins required for sexual reproduction have sufficiently diverged between the two species to prevent recombination in any mosquito blood meal in which gametocytes of both species are ingested. In order to investigate possible barriers to inter-species mating between P. ovale curtisi and P. ovale wallikeri, homologues of genes encoding sexual stage proteins in other plasmodia were identified and compared between the two species. Database searches with motifs for 6-cysteine, Limulus Coagulation factor C domain-containing proteins and other relevant sexual stage proteins in the genus Plasmodium were performed in the available P. ovale curtisi partial genome database (Wellcome Trust Sanger Institute, UK). Sequence fragments obtained were used as the basis for PCR walking along each gene of interest in reference isolates of both P. ovale curtisi and P. ovale wallikeri. Sequence alignment of the homologues of each gene in each species showed complete dimorphism across all isolates. In conclusion, substantial divergence between sexual stage proteins in the two P. ovale spp. was observed, providing further evidence that these do not recombine in nature. Incompatibility of proteins involved in sexual development and fertilisation thus remains a plausible explanation for the observed lack of natural recombination between P. ovale curtisi and P. ovale wallikeri.

  13. High prevalence and genetic diversity of Plasmodium malariae and no evidence of Plasmodium knowlesi in Bangladesh.

    PubMed

    Fuehrer, Hans-Peter; Swoboda, Paul; Harl, Josef; Starzengruber, Peter; Habler, Verena Elisabeth; Bloeschl, Ingrid; Haque, Rashidul; Matt, Julia; Khan, Wasif Ali; Noedl, Harald

    2014-04-01

    Although the prevalence of malaria remains high in parts of Bangladesh, there continues to be a substantial shortage of information regarding the less common malaria parasites such as Plasmodium malariae or Plasmodium knowlesi. Recent studies indicate that P. malariae may be extremely rare, and so far, there are no data on the presence (or absence) of P. knowlesi in southeastern Bangladesh. Genus- and species-specific nested polymerase chain reaction (PCR) analysis of the small subunit ribosomal RNA gene was performed to assess the presence and prevalence of P. malariae and P. knowlesi in 2,246 samples originating from asymptomatic and febrile participants of a cross-sectional and a febrile illnesses study in the Chittagong Hill Tracts in southeastern Bangladesh. P. malariae was detected in 60 samples (2.7%) corresponding to 8% of the 746 samples giving positive PCR results for Plasmodium sp., mainly because of the high prevalence (9.5%) among asymptomatic study participants testing positive for malaria. Symptomatic cases were more common (4.3% of all symptomatic malaria cases) during the dry season. Parasitemias were low (1,120-2,560/μl in symptomatic and 120-520/μl in asymptomatic carriers). Symptomatic patients presented mild to moderate symptoms like fever, chills, headache, dizziness, fatigue and myalgia.Although both the intermediate as well as the definite host are known to be endemic in southeastern Bangladesh, no evidence for the presence of P. knowlesi was found. We conclude that the role of P. malariae is highly underestimated in rural Bangladesh with major implications for malaria control and elimination strategies. PMID:24578257

  14. Avian Malaria ( Plasmodium spp.) in Captive Magellanic Penguins ( Spheniscus magellanicus ) from Northern Argentina, 2010.

    PubMed

    Vanstreels, Ralph Eric Thijl; Capellino, Félix; Silveira, Patricia; Braga, Érika M; Rodríguez-Heredia, Sergio Andres; Loureiro, Julio; Catão-Dias, José Luiz

    2016-07-01

    We report two cases of lethal avian malaria in Magellanic Penguins (Spheniscus magellanicus) captive at San Clemente del Tuyú, Argentina, approximately 560 km north of Argentinean breeding colonies of Magellanic Penguins. Blood smears revealed both penguins were concurrently infected by Plasmodium (Haemamoeba) tejerai, Plasmodium (Huffia) sp., and Plasmodium (Novyella) sp. PMID:27285418

  15. Plasmodium vivax trophozoite-stage proteomes

    PubMed Central

    Anderson, D.C.; Lapp, Stacey A.; Akinyi, Sheila; Meyer, Esmeralda V.S.; Barnwell, John W.; Korir-Morrison, Cindy; Galinski, Mary R.

    2015-01-01

    Plasmodium vivax is the causative infectious agent of 80–300 million annual cases of malaria. Many aspects of this parasite’s biology remain unknown. To further elucidate the interaction of P. vivax with its Saimiri boliviensis host, we obtained detailed proteomes of infected red blood cells, representing the trophozoite-enriched stage of development. Data from two of three biological replicate proteomes, emphasized here, were analyzed using five search engines, which enhanced identifications and resulted in the most comprehensive P. vivax proteomes to date, with 1375 P. vivax and 3209 S. boliviensis identified proteins. Ribosome subunit proteins were noted for both P. vivax and S. boliviensis, consistent with P. vivax’s known reticulocyte host–cell specificity. A majority of the host and pathogen proteins identified belong to specific functional categories, and several parasite gene families, while 33% of the P. vivax proteins have no reported function. Hemoglobin was significantly oxidized in both proteomes, and additional protein oxidation and nitration was detected in one of the two proteomes. Detailed analyses of these post-translational modifications are presented. The proteins identified here significantly expand the known P. vivax proteome and complexity of available host protein functionality underlying the host–parasite interactive biology, and reveal unsuspected oxidative modifications that may impact protein function. Biological significance Plasmodium vivax malaria is a serious neglected disease, causing an estimated 80 to 300 million cases annually in 95 countries. Infection can result in significant morbidity and possible death. P. vivax, unlike the much better-studied Plasmodium falciparum species, cannot be grown in long-term culture, has a dormant form in the liver called the hypnozoite stage, has a reticulocyte host–cell preference in the blood, and creates caveolae vesicle complexes at the surface of the infected reticulocyte

  16. A molecular mechanism of artemisinin resistance in Plasmodium falciparum malaria.

    PubMed

    Mbengue, Alassane; Bhattacharjee, Souvik; Pandharkar, Trupti; Liu, Haining; Estiu, Guillermina; Stahelin, Robert V; Rizk, Shahir S; Njimoh, Dieudonne L; Ryan, Yana; Chotivanich, Kesinee; Nguon, Chea; Ghorbal, Mehdi; Lopez-Rubio, Jose-Juan; Pfrender, Michael; Emrich, Scott; Mohandas, Narla; Dondorp, Arjen M; Wiest, Olaf; Haldar, Kasturi

    2015-04-30

    Artemisinins are the cornerstone of anti-malarial drugs. Emergence and spread of resistance to them raises risk of wiping out recent gains achieved in reducing worldwide malaria burden and threatens future malaria control and elimination on a global level. Genome-wide association studies (GWAS) have revealed parasite genetic loci associated with artemisinin resistance. However, there is no consensus on biochemical targets of artemisinin. Whether and how these targets interact with genes identified by GWAS, remains unknown. Here we provide biochemical and cellular evidence that artemisinins are potent inhibitors of Plasmodium falciparum phosphatidylinositol-3-kinase (PfPI3K), revealing an unexpected mechanism of action. In resistant clinical strains, increased PfPI3K was associated with the C580Y mutation in P. falciparum Kelch13 (PfKelch13), a primary marker of artemisinin resistance. Polyubiquitination of PfPI3K and its binding to PfKelch13 were reduced by the PfKelch13 mutation, which limited proteolysis of PfPI3K and thus increased levels of the kinase, as well as its lipid product phosphatidylinositol-3-phosphate (PI3P). We find PI3P levels to be predictive of artemisinin resistance in both clinical and engineered laboratory parasites as well as across non-isogenic strains. Elevated PI3P induced artemisinin resistance in absence of PfKelch13 mutations, but remained responsive to regulation by PfKelch13. Evidence is presented for PI3P-dependent signalling in which transgenic expression of an additional kinase confers resistance. Together these data present PI3P as the key mediator of artemisinin resistance and the sole PfPI3K as an important target for malaria elimination.

  17. A molecular mechanism of artemisinin resistance in Plasmodium falciparum malaria

    PubMed Central

    Mbengue, Alassane; Bhattacharjee, Souvik; Pandharkar, Trupti; Liu, Haining; Estiu, Guillermina; Stahelin, Robert V.; Rizk, Shahir; Njimoh, Dieudonne L.; Ryan, Yana; Chotivanich, Kesinee; Nguon, Chea; Ghorbal, Mehdi; Lopez-Rubio, Jose-Juan; Pfrender, Michael; Emrich, Scott; Mohandas, Narla; Dondorp, Arjen M.; Wiest, Olaf; Haldar, Kasturi

    2015-01-01

    Artemisinins are the corner stone of anti-malarial drugs1. Emergence and spread of resistance to them2–4 raises risk of wiping out recent gains achieved in reducing world-wide malaria burden and threatens future malaria control and elimination on a global level. Genome wide association studies (GWAS) have revealed parasite genetic loci associated with artemisinin resistance5–10. However, there is no consensus on biochemical targets of artemisinin. Whether and how these targets interact with genes identified by GWAS, remains unknown. Here we provide biochemical and cellular evidence that artemisinins are potent inhibitors of Plasmodium falciparum phosphatidylinositol-3-kinase (PfPI3K), revealing an unexpected mechanism of action. In resistant clinical strains, increased PfPI3K was associated with the C580Y mutation in P. falciparum Kelch13 (PfKelch13), a primary marker of artemisinin resistance. Polyubiquitination of PfPI3K and its binding to PfKelch13 were reduced by PfKelch13 mutation, which limited proteolysis of PfPI3K and thus increased levels of the kinase as well as its lipid product phosphatidylinositol 3-phosphate (PI3P). We find PI3P levels to be predictive of artemisinin resistance in both clinical and engineered laboratory parasites as well as across non-isogenic strains. Elevated PI3P induced artemisinin resistance in absence of PfKelch13 mutations, but remained responsive to regulation by PfKelch13. Evidence is presented for PI3P-dependent signaling, where transgenic expression of an additional kinase confers resistance. Together these data present PI3P as the key mediator of artemisinin resistance and the sole PfPI3K as an important target for malaria elimination. PMID:25874676

  18. Expression of PD-1/LAG-3 and cytokine production by CD4(+) T cells during infection with Plasmodium parasites.

    PubMed

    Doe, Henrietta T; Kimura, Daisuke; Miyakoda, Mana; Kimura, Kazumi; Akbari, Masoud; Yui, Katsuyuki

    2016-02-01

    CD4(+) T cells play critical roles in protection against the blood stage of malarial infection; however, their uncontrolled activation can be harmful to the host. In this study, in which rodent models of Plasmodium parasites were used, the expression of inhibitory receptors on activated CD4(+) T cells and their cytokine production was compared with their expression in a bacterial and another protozoan infection. CD4(+) T cells from mice infected with P. yoelii 17XL, P yoelii 17XNL, P. chabaudi, P. vinckei and P. berghei expressed the inhibitory receptors, PD-1 and LAG-3, as early as 6 days after infection, whereas those from either Listeria monocytogenes- or Leishmania major-infected mice did not. In response to T-cell receptor stimulation, CD4(+) T cells from mice infected with all the pathogens under study produced high concentrations of IFN-γ. IL-2 production was reduced in mice infected with Plasmodium species, but not in those infected with Listeria or Leishmania. In vitro blockade of the interaction between PD-1 and its ligands resulted in increased IFN-γ production in response to Plasmodium antigens, implying that PD-1 expressed on activated CD4(+) T cells actively inhibits T cell immune responses. Studies using Myd88(-/-), Trif(-/-) and Irf3(-/-) mice showed that induction of these CD4(+) T cells and their ability to produce cytokines is largely independent of TLR signaling. These studies suggest that expression of the inhibitory receptors PD-1 and LAG-3 on CD4(+) T cells and their reduced IL-2 production are common characteristic features of Plasmodium infection.

  19. Discovery of a Plasmodium falciparum glucose-6-phosphate dehydrogenase 6- phosphogluconolactonase inhibitor (R,Z)-N-((1-ethylpyrrolidin-2-yl)methyl)-2-(2-fluorobenzylidene)-3-oxo-3,4-dihydro-2H-benzo[b][1,4]thiazine-6-carboxamide (ML276) that reduces parasite growth in vitro

    PubMed Central

    Preuss, Janina; Maloney, Patrick; Peddibhotla, Satyamaheshwar; Hedrick, Michael P.; Hershberger, Paul; Gosalia, Palak; Milewski, Monika; Li, Yujie Linda; Sugarman, Eliot; Hood, Becky; Suyama, Eigo; Nguyen, Kevin; Vasile, Stefan; Sergienko, Eduard; Mangravita-Novo, Arianna; Vicchiarelli, Michael; McAnally, Danielle; Smith, Layton H.; Roth, Gregory P.; Diwan, Jena; Chung, Thomas D.Y.; Jortzik, Esther; Rahlfs, Stefan; Becker, Katja; Pinkerton, Anthony B.; Bode, Lars

    2012-01-01

    A high throughput screen of the NIH’s MLSMR collection of ~340,000 compounds was undertaken to identify compounds that inhibit Plasmodium falciparum glucose-6-phosphate dehydrogenase (PfG6PD). PfG6PD is essential for proliferating and propagating P. falciparum and differs structurally and mechanistically from the human ortholog. The reaction catalyzed by glucose-6-phosphate dehydrogenase (G6PD) is the first, rate-limiting step in the pentose phosphate pathway (PPP), a key metabolic pathway sustaining anabolic needs in reductive equivalents and synthetic materials in fastgrowing cells. In P. falciparum the bifunctional enzyme glucose-6-phosphate dehydrogenase-6- phosphogluconolactonase (PfGluPho) catalyzes the first two steps of the PPP. Because P. falciparum and infected host red blood cells rely on accelerated glucose flux, they depend on the G6PD activity of PfGluPho. The lead compound identified from this effort, (R,Z)-N-((1-ethylpyrrolidin-2-yl)methyl)-2- (2-fluorobenzylidene)-3-oxo-3,4-dihydro-2H-benzo[b][1,4]thiazine-6-carboxamide, 11, (ML276), is a submicromolar inhibitor of PfG6PD (IC50 = 889 nM). It is completely selective for the enzyme’s human isoform, displays micromolar potency (IC50 = 2.6 μM) against P. falciparum in culture, and has good drug-like properties, including high solubility and moderate microsomal stability. Studies testing the potential advantage of inhibiting PfG6PD in vivo are in progress. PMID:22813531

  20. The redox systems of Plasmodium falciparum and Plasmodium vivax: comparison, in silico analyses and inhibitor studies.

    PubMed

    Mohring, F; Pretzel, J; Jortzik, E; Becker, K

    2014-01-01

    Plasmodium falciparum is responsible for the most severe form of human malaria. P. vivax, in contrast, is the most widespread malaria parasite with an enormous impact on health and economy, since the infection is characterized by high rates of relapses. Due to the mild course of malaria tertiana and complicated in vitro culturing conditions of P. vivax, most of the research on malaria parasites has focused on P. falciparum so far. The redox metabolism of P. falciparum is a promising target for novel antimalarial drugs, since maintaining a redox equilibrium is of fundamental importance for the parasite. P. falciparum contains a cytosolic glutathione and thioredoxin system, as well as redox systems in the apicoplast and the mitochondrion. In contrast to P. falciparum, little is known about the redox processes in P. vivax so far. This review summarizes the current knowledge of the redox metabolism in malaria parasites and provides a detailed in silico comparison of the known and mostly well characterized redox enzymes from P. falciparum and the largely unknown redox proteins from P. vivax. Known antimalarials at least partially mediating their antiparasitic activity by influencing the redox balance of Plasmodium, including dehydroepiandrosterone, Mannich bases, methylene blue, and naphthoquinones, are discussed. Furthermore, we present novel inhibitors identified via screening of a compound library from the Leibniz Institute for Natural Product Research and Infection Biology, Jena that are active against the redox-related enzymes thioredoxin reductase, glutathione reductase, glutathione-S-transferase, and glucose-6-phosphate dehydrogenase 6- phosphoglucono- lactonase from P. falciparum.

  1. Induction of gene amplification in Plasmodium falciparum

    SciTech Connect

    Rogers, P.L.

    1985-01-01

    Human erythrocytic in vitro cultures of Honduras I strain of the malaria parasite Plasmodium falciparum have been stressed stepwise with increasing concentrations of methotrexate (MTX), a folate antagonist. This selection has produced a strain that is 450 times more resistant to the drug than the original culture. Uptake of sublethal doses of radiolabeled MTX by infected red blood cells was 6-36 times greater in the resistant cultures than in the nonresistant controls. DNA isolated from all of the parasites was probed by hybridization with /sup 35/S-labeled DNA derived from a clone of the yeast thymidylate synthetase (TS) gene. This showed 50 to 100 times more increased hybridization of the TS probe to the DNA from the resistant parasites is direct evidence of gene amplification because DHFR and TS are actually one and the same bifunctional enzyme in P. falciparum. Hence, the evidence presented indicates that induced resistance of the malaria parasite to MTX in this case is due to overproduction of DHFR resulting from amplification of the DHFR-TS gene.

  2. Risk factors for UK Plasmodium falciparum cases

    PubMed Central

    2014-01-01

    Background An increasing proportion of malaria cases diagnosed in UK residents with a history of travel to malaria endemic areas are due to Plasmodium falciparum. Methods In order to identify travellers at most risk of acquiring malaria a proportional hazards model was used to estimate the risk of acquiring malaria stratified by purpose of travel and age whilst adjusting for entomological inoculation rate (EIR) and duration of stay in endemic countries. Results Travellers visiting friends and relatives and business travellers were found to have significantly higher hazard of acquiring malaria (adjusted hazard ratio (HR) relative to that of holiday makers 7.4, 95% CI 6.4–8.5, p < 0. 0001 and HR 3.4, 95% CI 2.9-3.8, p < 0. 0001, respectively). All age-groups were at lower risk than children aged 0–15 years. Conclusions These estimates of the increased risk for business travellers and those visiting friends and relatives should be used to inform programmes to improve awareness of the risks of malaria when travelling. PMID:25091803

  3. Diagnosis and treatment of Plasmodium vivax malaria.

    PubMed

    Baird, Kevin J; Maguire, Jason D; Price, Ric N

    2012-01-01

    Infection by Plasmodium vivax poses unique challenges for diagnosis and treatment. Relatively low numbers of parasites in peripheral circulation may be difficult to confirm, and patients infected by dormant liver stages cannot be diagnosed before activation and the ensuing relapse. Radical cure thus requires therapy aimed at both the blood stages of the parasite (blood schizontocidal) and prevention of subsequent relapses (hypnozoitocidal). Chloroquine and primaquine have been the companion therapies of choice for the treatment of vivax malaria since the 1950s. Confirmed resistance to chloroquine occurs in much of the vivax endemic world and demands the investigation of alternative blood schizontocidal companions in radical cure. Such a shift in practice necessitates investigation of the safety and efficacy of primaquine when administered with those therapies, and the toxicity profile of such combination treatments, particularly in patients with glucose-6-phosphate dehydrogenase deficiency. These clinical studies are confounded by the frequency and timing of relapse among strains of P. vivax, and potentially by differing susceptibilities to primaquine. The inability to maintain this parasite in continuous in vitro culture greatly hinders new drug discovery. Development of safe and effective chemotherapies for vivax malaria for the coming decades requires overcoming these challenges. PMID:23199489

  4. Detection of SUMOylation in Plasmodium falciparum.

    PubMed

    Reiter, Katherine H; Matunis, Michael J

    2016-01-01

    Reversible protein modification by small ubiquitin-related modifiers (SUMOs) regulates many cellular processes, including transcription, protein quality control, cell division, and oxidative stress. SUMOylation is therefore essential for normal cell function and represents a potentially valuable target for the development of inhibitors of pathogenic eukaryotic organisms, including the malaria parasite, Plasmodium falciparum (Pf). The specific and essential functions of SUMOylation in Pf, however, remain largely uncharacterized. The further development of antimalarial drugs targeting SUMOylation would benefit significantly from a more detailed understanding of its functions and regulation during the parasite life cycle. The recent development of antibodies specific for Pf SUMO provides a valuable tool to study the functions and regulation of SUMOylation. In preliminary studies, we have used immunoblot analysis to demonstrate that SUMOylation levels vary significantly in parasites during different stages of the red blood cell cycle and also in response to oxidative stress. Owing to the dynamic nature of SUMOylation and to the robust activity of SUMO isopeptidases, analysis of SUMOylation in cultured Pf parasites requires a number of precautions during parasite purification and lysis. Here, we outline methods for preserving SUMO conjugates during isolation of Pf parasites from human red blood cell cultures, and for their detection by immunoblot analysis using PfSUMO-specific antibodies. PMID:27631812

  5. Plasmodium vivax blood-stage dynamics.

    PubMed

    McKenzie, F Ellis; Jeffery, Geoffrey M; Collins, William E

    2002-06-01

    We examine the dynamics of parasitemia and gametocytemia reflected in the preintervention charts of 221 malaria-naive U.S. neurosyphilis patients infected with the St. Elizabeth strain of Plasmodium vivax, for malariatherapy, focusing on the 109 charts for which 15 or more days of patency preceded intervention and daily records encompassed an average 98% of the duration of each infection. Our approximations of merogony cycles (via "local peaks" in parasitemia) seldom fit patterns that correspond to "textbook" tertian brood structures. Peak parasitemia was higher in trophozoite-induced infections than in sporozoite-induced ones. Relative densities of male and female gametocytes appeared to alternate, though without a discernably regular period. Successful transmission to mosquitoes did not depend on detectable gametocytemia or on absence of fever. When gametocytes were detected, transmission success depended on densities of only male gametocytes. Successful feeds occurred on average 4.7 days later in an infection than did failures. Parasitemia was lower in homologous reinfection, gametocytemia lower or absent. PMID:12099421

  6. Plasmodium falciparum Secretome in Erythrocyte and Beyond

    PubMed Central

    Soni, Rani; Sharma, Drista; Bhatt, Tarun K.

    2016-01-01

    Plasmodium falciparum is the causative agent of deadly malaria disease. It is an intracellular eukaryote and completes its multi-stage life cycle spanning the two hosts viz, mosquito and human. In order to habituate within host environment, parasite conform several strategies to evade host immune responses such as surface antigen polymorphism or modulation of host immune system and it is mediated by secretion of proteins from parasite to the host erythrocyte and beyond, collectively known as, malaria secretome. In this review, we will discuss about the deployment of parasitic secretory protein in mechanism implicated for immune evasion, protein trafficking, providing virulence, changing permeability and cyto-adherence of infected erythrocyte. We will be covering the possibilities of developing malaria secretome as a drug/vaccine target. This gathered information will be worthwhile in depicting a well-organized picture for host-pathogen interplay during the malaria infection and may also provide some clues for the development of novel anti-malarial therapies. PMID:26925057

  7. Glutathione-deficient Plasmodium berghei parasites exhibit growth delay and nuclear DNA damage.

    PubMed

    Padín-Irizarry, Vivian; Colón-Lorenzo, Emilee E; Vega-Rodríguez, Joel; Castro, María Del R; González-Méndez, Ricardo; Ayala-Peña, Sylvette; Serrano, Adelfa E

    2016-06-01

    Plasmodium parasites are exposed to endogenous and exogenous oxidative stress during their complex life cycle. To minimize oxidative damage, the parasites use glutathione (GSH) and thioredoxin (Trx) as primary antioxidants. We previously showed that disruption of the Plasmodium berghei gamma-glutamylcysteine synthetase (pbggcs-ko) or the glutathione reductase (pbgr-ko) genes resulted in a significant reduction of GSH in intraerythrocytic stages, and a defect in growth in the pbggcs-ko parasites. In this report, time course experiments of parasite intraerythrocytic development and morphological studies showed a growth delay during the ring to schizont progression. Morphological analysis shows a significant reduction in size (diameter) of trophozoites and schizonts with increased number of cytoplasmic vacuoles in the pbggcs-ko parasites in comparison to the wild type (WT). Furthermore, the pbggcs-ko mutants exhibited an impaired response to oxidative stress and increased levels of nuclear DNA (nDNA) damage. Reduced GSH levels did not result in mitochondrial DNA (mtDNA) damage or protein carbonylations in neither pbggcs-ko nor pbgr-ko parasites. In addition, the pbggcs-ko mutant parasites showed an increase in mRNA expression of genes involved in oxidative stress detoxification and DNA synthesis, suggesting a potential compensatory mechanism to allow for parasite proliferation. These results reveal that low GSH levels affect parasite development through the impairment of oxidative stress reduction systems and damage to the nDNA. Our studies provide new insights into the role of the GSH antioxidant system in the intraerythrocytic development of Plasmodium parasites, with potential translation into novel pharmacological interventions. PMID:26952808

  8. Discriminating Protective from Nonprotective Plasmodium-Specific CD8+ T Cell Responses.

    PubMed

    Doll, Katherine L; Pewe, Lecia L; Kurup, Samarchith P; Harty, John T

    2016-05-15

    Despite decades of research, malaria remains a global health crisis. Current subunit vaccine approaches do not provide efficient long-term, sterilizing immunity against Plasmodium infections in humans. Conversely, whole parasite vaccinations with their larger array of target Ags have conferred long-lasting sterilizing protection to humans. Similar studies in rodent models of malaria reveal that CD8(+) T cells play a critical role in liver-stage immunity after whole parasite vaccination. However, it is unknown whether all CD8(+) T cell specificities elicited by whole parasite vaccination contribute to protection, an issue of great relevance for enhanced subunit vaccination. In this article, we show that robust CD8(+) T cell responses of similar phenotype are mounted after prime-boost immunization against Plasmodium berghei glideosome-associated protein 5041-48-, sporozoite-specific protein 20318-325-, thrombospondin-related adhesion protein (TRAP) 130-138-, or circumsporozoite protein (CSP) 252-260-derived epitopes in mice, but only CSP252-260- and TRAP130-138-specific CD8(+) T cells provide sterilizing immunity and reduce liver parasite burden after sporozoite challenge. Further, CD8(+) T cells specific to sporozoite surface-expressed CSP and TRAP proteins, but not intracellular glideosome-associated protein 50 and sporozoite-specific protein 20, efficiently recognize sporozoite-infected hepatocytes in vitro. These results suggest that: 1) protection-relevant antigenic targets, regardless of their immunogenic potential, must be efficiently presented by infected hepatocytes for CD8(+) T cells to eliminate liver-stage Plasmodium infection; and 2) proteins expressed on the surface of sporozoites may be good target Ags for protective CD8(+) T cells. PMID:27084099

  9. Epidemiological and clinical features of Plasmodium falciparum malaria in united nations personnel in Western Bahr el Ghazal State, South Sudan.

    PubMed

    He, Dengming; Zhang, Yuqi; Liu, Xiaofeng; Guo, Shimin; Zhao, Donghong; Zhu, Yunjie; Li, Huaidong; Kong, Li

    2013-01-01

    Western Bahr el Ghazal State is located in northwestern South Sudan, which is a tropical area subject to Plasmodium falciparum malaria epidemics. The aim of this study is to explore the epidemiological and clinical features of Plasmodium falciparum malaria in United Nations personnel stationed in this area. From July 2006 to June 2009, epidemiological data and medical records of 678 patients with Plasmodium falciparum malaria at the U.N. level 2 hospital were analyzed. The U.N. personnel were divided into individuals not immune to Plasmodium falciparum and individuals semi-immune to Plasmodium falciparum. The patients were divided into a chemoprophylaxis group (non-immune individuals who complied with the chemoprophylaxis regimen, 582 cases) and a no/incomplete chemoprophylaxis group (non-immune individuals who either did not fully comply with chemoprophylaxis or did not use it at all and semi-immune individuals who did not use chemoprophylaxis, 96 cases). Overall morbidity was about 11.3%. There was a significant difference in the morbidity of semi-immune and non-immune individuals (1.3% vs. 15.1%, P<0.001). Out of the total, 82.9% of cases occurred during the rainy season. The incidence of fever in the chemoprophylaxis group was significantly lower than in the no/incomplete chemoprophylaxis group (36.8% vs. 96.9%, P<0.001). Significant differences were observed between the two groups with respect to all other malaria-like symptoms except gastrointestinal symptoms, serum glucose level, platelet count, and alanine aminotransferase level. The incidence of complications was 1.2% (chemoprophylaxis group) and 44.8% (no/incomplete chemoprophylaxis group).The most common complication was thrombocytopenia, which was seen in 40.6% of the no/incomplete chemoprophylaxis group. In summary, Plasmodium falciparum malaria mainly occurred in rainy season. Gastrointestinal symptoms are an important precursor of malaria. Blood smears and rapid diagnostic tests should be performed

  10. Plasmodium knowlesi: from severe zoonosis to animal model.

    PubMed

    Cox-Singh, Janet; Culleton, Richard

    2015-06-01

    Plasmodium knowlesi malaria is a newly described zoonosis in Southeast Asia. Similarly to Plasmodium falciparum, P. knowlesi can reach high parasitaemia in the human host and both species cause severe and fatal illness. Interpretation of host-parasite interactions in studies of P. knowlesi malaria adds a counterpoint to studies on P. falciparum. However, there is no model system for testing the resulting hypotheses on malaria pathophysiology or for developing new interventions. Plasmodium knowlesi is amenable to genetic manipulation in vitro and several nonhuman primate species are susceptible to experimental infection. Here, we make a case for drawing on P. knowlesi as both a human pathogen and an experimental model to lift the roadblock between malaria research and its translation into human health benefits.

  11. Diagnosis of an imported Plasmodium ovale wallikeri infection in Malaysia.

    PubMed

    Liew, Jonathan Wee Kent; Mahmud, Rohela; Tan, Lian Huat; Lau, Yee Ling

    2016-01-06

    Plasmodium ovale is rare and not exactly known to be autochthonous in Malaysia. There are two distinct forms of the parasite, namely P. ovale curtisi (classic form) and P. ovale wallikeri (variant form). Here, the first sequence confirmed case of an imported P. ovale wallikeri infection in Malaysia is presented. Microscopy found Plasmodium parasites with morphology similar to P. ovale or Plasmodium vivax in the blood films. Further confirmation using polymerase chain reaction (PCR) targeting the small-subunit rRNA gene of the parasite was unsuccessful. Genus-specific PCR was then performed and the product was sequenced and analysed. Sequence analyses confirmed the aetiological agent as P. ovale wallikeri. New species-specific primers (rOVA1v and rOVA2v) were employed and P. ovale wallikeri was finally confirmed. The findings highlight the need to look out for imported malaria infections in Malaysia and the importance of a constantly updated and validated diagnostic technique.

  12. Optimal strategy for controlling the spread of Plasmodium Knowlesi malaria: Treatment and culling

    NASA Astrophysics Data System (ADS)

    Abdullahi, Mohammed Baba; Hasan, Yahya Abu; Abdullah, Farah Aini

    2015-05-01

    Plasmodium Knowlesi malaria is a parasitic mosquito-borne disease caused by a eukaryotic protist of genus Plasmodium Knowlesi transmitted by mosquito, Anopheles leucosphyrus to human and macaques. We developed and analyzed a deterministic Mathematical model for the transmission of Plasmodium Knowlesi malaria in human and macaques. The optimal control theory is applied to investigate optimal strategies for controlling the spread of Plasmodium Knowlesi malaria using treatment and culling as control strategies. The conditions for optimal control of the Plasmodium Knowlesi malaria are derived using Pontryagin's Maximum Principle. Finally, numerical simulations suggested that the combination of the control strategies is the best way to control the disease in any community.

  13. [From malaria parasite point of view--Plasmodium falciparum evolution].

    PubMed

    Zerka, Agata; Kaczmarek, Radosław; Jaśkiewicz, Ewa

    2015-12-31

    Malaria is caused by infection with protozoan parasites belonging to the genus Plasmodium, which have arguably exerted the greatest selection pressure on humans in the history of our species. Besides humans, different Plasmodium parasites infect a wide range of animal hosts, from marine invertebrates to primates. On the other hand, individual Plasmodium species show high host specificity. The extraordinary evolution of Plasmodium probably began when a free-living red algae turned parasitic, and culminated with its ability to thrive inside a human red blood cell. Studies on the African apes generated new data on the evolution of malaria parasites in general and the deadliest human-specific species, Plasmodium falciparum, in particular. Initially, it was hypothesized that P. falciparum descended from the chimpanzee malaria parasite P. reichenowi, after the human and the chimp lineage diverged about 6 million years ago. However, a recently identified new species infecting gorillas, unexpectedly showed similarity to P. falciparum and was therefore named P. praefalciparum. That finding spurred an alternative hypothesis, which proposes that P. falciparum descended from its gorilla rather than chimp counterpart. In addition, the gorilla-to-human host shift may have occurred more recently (about 10 thousand years ago) than the theoretical P. falciparum-P. reichenowi split. One of the key aims of the studies on Plasmodium evolution is to elucidate the mechanisms that allow the incessant host shifting and retaining the host specificity, especially in the case of human-specific species. Thorough understanding of these phenomena will be necessary to design effective malaria treatment and prevention strategies.

  14. Plasmodium knowlesi as a Threat to Global Public Health

    PubMed Central

    Wesolowski, Roland; Wozniak, Alina; Mila-Kierzenkowska, Celestyna; Szewczyk-Golec, Karolina

    2015-01-01

    Malaria is a tropical disease caused by protozoans of the Plasmodium genus. Delayed diagnosis and misdiagnosis are strongly associated with higher mortality. In recent years, a greater importance is attributed to Plasmodium knowlesi, a species found mainly in Southeast Asia. Routine parasitological diagnostics are associated with certain limitations and difficulties in unambiguous determination of the parasite species based only on microscopic image. Recently, molecular techniques have been increasingly used for predictive diagnosis. The aim of the study is to draw attention to the risk of travelling to knowlesi malaria endemic areas and to raise awareness among personnel involved in the therapeutic process. PMID:26537037

  15. Analysis of expressed sequence tags from Plasmodium falciparum.

    PubMed

    Chakrabarti, D; Reddy, G R; Dame, J B; Almira, E C; Laipis, P J; Ferl, R J; Yang, T P; Rowe, T C; Schuster, S M

    1994-07-01

    An initiative was undertaken to sequence all genes of the human malaria parasite Plasmodium falciparum in an effort to gain a better understanding at the molecular level of the parasite that inflicts much suffering in the developing world. 550 random complimentary DNA clones were partially sequenced from the intraerythrocytic form of the parasite as one of the approaches to analyze the transcribed sequences of its genome. The sequences, after editing, generated 389 expressed sequence tag sites and over 105 kb of DNA sequences. About 32% of these clones showed significant homology with other genes in the database. These clones represent 340 new Plasmodium falciparum expressed sequence tags.

  16. Replication and maintenance of the Plasmodium falciparum apicoplast genome.

    PubMed

    Milton, Morgan E; Nelson, Scott W

    2016-08-01

    Members of the phylum Apicomplexa are responsible for many devastating diseases including malaria (Plasmodium spp.), toxoplasmosis (Toxoplasma gondii), babesiosis (Babesia bovis), and cyclosporiasis (Cyclospora cayetanensis). Most Apicomplexans contain a unique and essential organelle called the apicoplast. Derived from an ancient chloroplast, the apicoplast replicates and maintains a 35 kilobase (kb) circular genome. Due to its essential nature within the parasite, drugs targeted to proteins involved in DNA replication and repair of the apicoplast should be potent and specific. This review summarizes the current knowledge surrounding the replication and repair of the Plasmodium falciparum apicoplast genome and identifies several putative proteins involved in replication and repair pathways. PMID:27338018

  17. Red Blood Cell Polymorphism and Susceptibility to Plasmodium vivax

    PubMed Central

    Zimmerman, Peter A.; Ferreira, Marcelo U.; Howes, Rosalind E.; Mercereau-Puijalon, Odile

    2013-01-01

    Resistance to Plasmodium vivax blood-stage infection has been widely recognised to result from absence of the Duffy (Fy) blood group from the surface of red blood cells (RBCs) in individuals of African descent. Interestingly, recent studies from different malaria-endemic regions have begun to reveal new perspectives on the association between Duffy gene polymorphism and P. vivax malaria. In Papua New Guinea and the Americas, heterozygous carriers of a Duffy-negative allele are less susceptible to P. vivax infection than Duffy-positive homozygotes. In Brazil, studies show that the Fya antigen, compared to Fyb, is associated with lower binding to the P. vivax Duffy-binding protein and reduced susceptibility to vivax malaria. Additionally, it is interesting that numerous studies have now shown that P. vivax can infect RBCs and cause clinical disease in Duffy-negative people. This suggests that the relationship between P. vivax and the Duffy antigen is more complex than customarily described. Evidence of P. vivax Duffy-independent red cell invasion indicates that the parasite must be evolving alternative red cell invasion pathways. In this chapter, we review the evidence for P. vivax Duffy-dependent and Duffy-independent red cell invasion. We also consider the influence of further host gene polymorphism associated with malaria endemicity on susceptibility to vivax malaria. The interaction between the parasite and the RBC has significant potential to influence the effectiveness of P. vivax-specific vaccines and drug treatments. Ultimately, the relationships between red cell polymorphisms and P. vivax blood-stage infection will influence our estimates on the population at risk and efforts to eliminate vivax malaria. PMID:23384621

  18. Plasmodium vivax Diversity and Population Structure across Four Continents

    PubMed Central

    Koepfli, Cristian; Rodrigues, Priscila T.; Antao, Tiago; Orjuela-Sánchez, Pamela; Van den Eede, Peter; Gamboa, Dionicia; van Hong, Nguyen; Bendezu, Jorge; Erhart, Annette; Barnadas, Céline; Ratsimbasoa, Arsène; Menard, Didier; Severini, Carlo; Menegon, Michela; Nour, Bakri Y. M.; Karunaweera, Nadira; Mueller, Ivo; Ferreira, Marcelo U.; Felger, Ingrid

    2015-01-01

    Plasmodium vivax is the geographically most widespread human malaria parasite. To analyze patterns of microsatellite diversity and population structure across countries of different transmission intensity, genotyping data from 11 microsatellite markers was either generated or compiled from 841 isolates from four continents collected in 1999–2008. Diversity was highest in South-East Asia (mean allelic richness 10.0–12.8), intermediate in the South Pacific (8.1–9.9) Madagascar and Sudan (7.9–8.4), and lowest in South America and Central Asia (5.5–7.2). A reduced panel of only 3 markers was sufficient to identify approx. 90% of all haplotypes in South Pacific, African and SE-Asian populations, but only 60–80% in Latin American populations, suggesting that typing of 2–6 markers, depending on the level of endemicity, is sufficient for epidemiological studies. Clustering analysis showed distinct clusters in Peru and Brazil, but little sub-structuring was observed within Africa, SE-Asia or the South Pacific. Isolates from Uzbekistan were exceptional, as a near-clonal parasite population was observed that was clearly separated from all other populations (FST>0.2). Outside Central Asia FST values were highest (0.11–0.16) between South American and all other populations, and lowest (0.04–0.07) between populations from South-East Asia and the South Pacific. These comparisons between P. vivax populations from four continents indicated that not only transmission intensity, but also geographical isolation affect diversity and population structure. However, the high effective population size results in slow changes of these parameters. This persistency must be taken into account when assessing the impact of control programs on the genetic structure of parasite populations. PMID:26125189

  19. Plasmodium vivax Diversity and Population Structure across Four Continents.

    PubMed

    Koepfli, Cristian; Rodrigues, Priscila T; Antao, Tiago; Orjuela-Sánchez, Pamela; Van den Eede, Peter; Gamboa, Dionicia; van Hong, Nguyen; Bendezu, Jorge; Erhart, Annette; Barnadas, Céline; Ratsimbasoa, Arsène; Menard, Didier; Severini, Carlo; Menegon, Michela; Nour, Bakri Y M; Karunaweera, Nadira; Mueller, Ivo; Ferreira, Marcelo U; Felger, Ingrid

    2015-01-01

    Plasmodium vivax is the geographically most widespread human malaria parasite. To analyze patterns of microsatellite diversity and population structure across countries of different transmission intensity, genotyping data from 11 microsatellite markers was either generated or compiled from 841 isolates from four continents collected in 1999-2008. Diversity was highest in South-East Asia (mean allelic richness 10.0-12.8), intermediate in the South Pacific (8.1-9.9) Madagascar and Sudan (7.9-8.4), and lowest in South America and Central Asia (5.5-7.2). A reduced panel of only 3 markers was sufficient to identify approx. 90% of all haplotypes in South Pacific, African and SE-Asian populations, but only 60-80% in Latin American populations, suggesting that typing of 2-6 markers, depending on the level of endemicity, is sufficient for epidemiological studies. Clustering analysis showed distinct clusters in Peru and Brazil, but little sub-structuring was observed within Africa, SE-Asia or the South Pacific. Isolates from Uzbekistan were exceptional, as a near-clonal parasite population was observed that was clearly separated from all other populations (FST>0.2). Outside Central Asia FST values were highest (0.11-0.16) between South American and all other populations, and lowest (0.04-0.07) between populations from South-East Asia and the South Pacific. These comparisons between P. vivax populations from four continents indicated that not only transmission intensity, but also geographical isolation affect diversity and population structure. However, the high effective population size results in slow changes of these parameters. This persistency must be taken into account when assessing the impact of control programs on the genetic structure of parasite populations.

  20. Plasmodium AdoMetDC/ODC bifunctional enzyme is essential for male sexual stage development and mosquito transmission

    PubMed Central

    Hart, Robert J.; Ghaffar, Atif; Abdalal, Shaymaa; Perrin, Benjamin

    2016-01-01

    ABSTRACT Polyamines are positively-charged organic molecules that are important for cellular growth and division. Polyamines and their synthesizing enzymes are particularly abundant in rapidly proliferating eukaryotic cells such as parasitic protozoa and cancer cells. Polyamine biosynthesis inhibitors, such as Elfornithine, are now being considered for cancer prevention and have been used effectively against Trypanosoma brucei. Inhibitors of polyamine biosynthesis have caused growth arrest of Plasmodium falciparum blood stages in vitro, but in P. berghei only partial inhibition has been observed. While polyamine biosynthesis enzymes are characterized and conserved in Plasmodium spp., little is known on the biological roles of these enzymes inside malaria parasite hosts. The bifunctional polyamine biosynthesis enzyme S-adenosyl methionine decarboxylase/ornithine decarboxylase (AdoMetDC/ODC) was targeted for deletion in P. yoelii. Deletion of AdoMetDC/ODC significantly reduced blood stage parasitemia but Anopheles transmission was completely blocked. We showed that male gametocytogenesis and male gamete exflagellation were abolished and consequently no ookinetes or oocyst sporozoites could be generated from adometdc/odc(–) parasites. Supplementation of putrescine and spermidine did not rescue the defective phenotypes of male gametocytes and gametes of the knockout parasites. These results highlight the crucial role of polyamine homeostasis in the development and functions of Plasmodium erythrocytic stages in the blood and in the mosquito vector and validate polyamine biosynthesis pathway enzymes as drug targeting candidates for malaria parasite transmission blocking. PMID:27387533

  1. Kix domain specific Immunoglobulin A can protect from adverse lung and cerebral pathology induced by Plasmodium berghei ANKA.

    PubMed

    Kumar, Anil; Deore, Sapna; Kumar, Santosh; Bankar, Tanuja; Lotke, Anil; Parab, Pradeep; Krishnasastry, Musti

    2015-08-28

    Plasmodium specific IgA has been detected in serum and breast milk among the endemic population but the role it can play in vivo is not clear. In this report, we demonstrate the utility of Malaria specific IgA, elicited by peptide sequences (referred as Mpep3 and Mpep4) of region VI of EBA-175 (PfrVI). Immunization of mice with KLH tagged or untagged peptides of Mpep3, Mpep4 or with PfrVI have resulted in specific IgA response that inhibits the in vitro invasion of Plasmodium falciparum merozoites. Mice having the IgA specific to Mpep4 have exhibited higher tolerance to Plasmodium berghei ANKA parasitemia, exhibited several fold lesser sequestration of infected RBC, lesser damage to microvasculature with no signs of perivascular haemorrhage and lesser lung inflammation in comparison to unimmunized mice. In addition, the immunized mice have B-cell population that secrete the IgA specific to PfrVI. These results suggest that the IgA specific to these malarial antigens can confer significant advantage to hosts and it may also reduce the severity of malaria infection. PMID:26188504

  2. The Plasmodium TRAP/MIC2 family member, TRAP-Like Protein (TLP), is involved in tissue traversal by sporozoites.

    PubMed

    Moreira, Cristina K; Templeton, Thomas J; Lavazec, Catherine; Hayward, Rhian E; Hobbs, Charlotte V; Kroeze, Hans; Janse, Chris J; Waters, Andrew P; Sinnis, Photini; Coppi, Alida

    2008-07-01

    In the apicomplexan protozoans motility and cell invasion are mediated by the TRAP/MIC2 family of transmembrane proteins, members of which link extracellular adhesion to the intracellular actomyosin motor complex. Here we characterize a new member of the TRAP/MIC2 family, named TRAP-Like Protein (TLP), that is highly conserved within the Plasmodium genus. Similar to the Plasmodium sporozoite protein, TRAP, and the ookinete protein, CTRP, TLP possesses an extracellular domain architecture that is comprised of von Willebrand factor A (vWA) and thrombospondin type 1 (TSP1) domains, plus a short cytoplasmic domain. Comparison of the vWA domain of TLP genes from multiple Plasmodium falciparum isolates showed relative low sequence diversity, suggesting that the protein is not under selective pressures of the host immune system. Analysis of transcript levels by quantitative reverse transcription polymerase chain reaction (RT-PCR) showed that TLP is predominantly expressed in salivary gland sporozoites of P. falciparum and P. berghei. Targeted disruption of P. berghei TLP resulted in a decreased capacity for cell traversal by sporozoites, and reduced infectivity of sporozoites in vivo, whereas in vitro sporozoite motility and hepatocyte invasion were unaffected. These results indicate a role of TLP in cell traversal by sporozoites.

  3. Artemisinin-resistant Plasmodium falciparum malaria

    PubMed Central

    Fairhurst, Rick M.; Dondorp, Arjen M.

    2016-01-01

    For more than five decades, Southeast Asia (SEA) has been fertile ground for the emergence of drug-resistant Plasmodium falciparum malaria. After generating parasites resistant to chloroquine, sulfadoxine, pyrimethamine, quinine, and mefloquine, this region has now spawned parasites resistant to artemisinins – the world's most potent antimalarial drugs. In areas where artemisinin resistance is prevalent, artemisinin combination therapies (ACTs) – the first-line treatments for malaria – are failing fast. This worrisome development threatens to make malaria practically untreatable in SEA, and threatens to compromise global endeavors to eliminate this disease. A recent series of clinical, in-vitro, genomics, and transcriptomics studies in SEA have defined in-vivo and in-vitro phenotypes of artemisinin resistance; identified its causal genetic determinant; explored its molecular mechanism; and assessed its clinical impact. Specifically, these studies have established that artemisinin resistance manifests as slow parasite clearance in patients and increased survival of early ring-stage parasites in vitro; is caused by single nucleotide polymorphisms in the parasite's ‘K13’ gene; is associated with an upregulated “unfolded protein response” pathway that may antagonize the pro-oxidant activity of artemisinins; and selects for partner drug resistance that rapidly leads to ACT failures. In SEA, clinical studies are urgently needed to monitor ACT efficacy where K13 mutations are prevalent; test whether new combinations of currently-available drugs cure ACT failures; and advance new antimalarial compounds through preclinical pipelines and into clinical trials. Intensifying these efforts should help to forestall the spread of artemisinin and partner drug resistance from SEA to Sub-Saharan Africa, where the world's malaria transmission, morbidity, and mortality rates are highest. PMID:27337450

  4. Discovery of Novel and Ligand-Efficient Inhibitors of Plasmodium falciparum and Plasmodium vivaxN-Myristoyltransferase

    PubMed Central

    2012-01-01

    N-Myristoyltransferase (NMT) is an attractive antiprotozoan drug target. A lead-hopping approach was utilized in the design and synthesis of novel benzo[b]thiophene-containing inhibitors of Plasmodium falciparum (Pf) and Plasmodium vivax (Pv) NMT. These inhibitors are selective against Homo sapiens NMT1 (HsNMT), have excellent ligand efficiency (LE), and display antiparasitic activity in vitro. The binding mode of this series was determined by crystallography and shows a novel binding mode for the benzothiophene ring. PMID:23170970

  5. Isolation of invasive Plasmodium yoelii merozoites with a long half-life to evaluate invasion dynamics and potential invasion inhibitors.

    PubMed

    Mutungi, Joe Kimanthi; Yahata, Kazuhide; Sakaguchi, Miako; Kaneko, Osamu

    2015-11-01

    Malaria symptoms and pathogenesis are caused by blood stage parasite burdens of Plasmodium spp., for which invasion of red blood cells (RBCs) by merozoites is essential. Successful targeting by either drugs or vaccines directed against the whole merozoite or its antigens during its transient extracellular status would contribute to malaria control by impeding RBC invasion. To understand merozoite invasion biology and mechanisms, it is desired to obtain merozoites that retain their invasion activity in vitro. Accordingly, methods have been developed to isolate invasive Plasmodium knowlesi and Plasmodium falciparum merozoites. Rodent malaria parasite models offer ease in laboratory maintenance and experimental genetic modifications; however, no methods have been reported regarding isolation of high numbers of invasive rodent malaria merozoites. In this study, Plasmodium yoelii-infected RBCs were obtained from infected mice, and mature schizont-infected RBCs enriched via Histodenz™ density gradients. Merozoites retaining invasion activity were then isolated by passing the preparations through a filter membrane. RBC-invaded parasites developed to mature stages in vitro in a synchronous manner. Isolated merozoites were evaluated for retention of invasion activity following storage at different temperatures prior to incubation with uninfected mouse RBCs. Isolated merozoites retained their invasion activity 4h after isolation at 10 or 15 °C, whereas their invasion activity reduced to 0-10% within 30 min when incubated on ice or at 37 °C prior to RBC invasion assay. Images of merozoites at successive steps during RBC invasion were captured by light and transmission electron microscopy. Synthetic peptides derived from the amino acid sequence of the P. yoelii invasion protein RON2 efficiently inhibited RBC invasion. The developed method to isolate and keep invasive P. yoelii merozoites for up to 4h is a powerful tool to study the RBC invasion biology of this parasite

  6. Structural and functional characterization of an iron-sulfur cluster assembly scaffold protein-SufA from Plasmodium vivax.

    PubMed

    Pala, Zarna Rajeshkumar; Saxena, Vishal; Saggu, Gagandeep Singh; Yadav, Sushil Kumar; Pareek, R P; Kochar, Sanjay Kumar; Kochar, Dhanpat Kumar; Garg, Shilpi

    2016-07-01

    Iron-sulfur (Fe-S) clusters are utilized as prosthetic groups in all living organisms for diverse range of cellular processes including electron transport in respiration and photosynthesis, sensing of ambient conditions, regulation of gene expression and catalysis. In Plasmodium, two Fe-S cluster biogenesis pathways are reported, of which the Suf pathway in the apicoplast has been shown essential for the erythrocytic stages of the parasite. While the initial components of this pathway detailing the sulfur mobilization have been elucidated, the components required for the assembly and transfer of Fe-S clusters are not reported from the parasite. In Escherichia coli, SufB acts as a scaffold protein and SufA traffics the assembled Fe-S cluster from SufB to target apo-proteins. However, in Plasmodium, the homologs of these proteins are yet to be characterized for their function. Here, we report a putative SufA protein from Plasmodium vivax with signature motifs of A-type scaffold proteins, which is evolutionarily conserved. The presence of the [Fe4S4](3+) cluster under reduced conditions was confirmed by UV-visible and EPR spectroscopy and the interaction of these clusters with the conserved cysteine residues of chains A and B of PvSufA, validates its existence as a dimer, similar to that in E. coli. The H-bond interactions at the PvSufA-SufB interface demonstrate SufA as a scaffold protein in conjunction with SufB for the pre-assembly of Fe-S clusters and their transfer to the target proteins. Co-localization of the protein to the apicoplast further provides an experimental evidence of a functional scaffold protein SufA for the biogenesis of Fe-S clusters in apicoplast of Plasmodium. PMID:27033210

  7. Structural and functional characterization of an iron-sulfur cluster assembly scaffold protein-SufA from Plasmodium vivax.

    PubMed

    Pala, Zarna Rajeshkumar; Saxena, Vishal; Saggu, Gagandeep Singh; Yadav, Sushil Kumar; Pareek, R P; Kochar, Sanjay Kumar; Kochar, Dhanpat Kumar; Garg, Shilpi

    2016-07-01

    Iron-sulfur (Fe-S) clusters are utilized as prosthetic groups in all living organisms for diverse range of cellular processes including electron transport in respiration and photosynthesis, sensing of ambient conditions, regulation of gene expression and catalysis. In Plasmodium, two Fe-S cluster biogenesis pathways are reported, of which the Suf pathway in the apicoplast has been shown essential for the erythrocytic stages of the parasite. While the initial components of this pathway detailing the sulfur mobilization have been elucidated, the components required for the assembly and transfer of Fe-S clusters are not reported from the parasite. In Escherichia coli, SufB acts as a scaffold protein and SufA traffics the assembled Fe-S cluster from SufB to target apo-proteins. However, in Plasmodium, the homologs of these proteins are yet to be characterized for their function. Here, we report a putative SufA protein from Plasmodium vivax with signature motifs of A-type scaffold proteins, which is evolutionarily conserved. The presence of the [Fe4S4](3+) cluster under reduced conditions was confirmed by UV-visible and EPR spectroscopy and the interaction of these clusters with the conserved cysteine residues of chains A and B of PvSufA, validates its existence as a dimer, similar to that in E. coli. The H-bond interactions at the PvSufA-SufB interface demonstrate SufA as a scaffold protein in conjunction with SufB for the pre-assembly of Fe-S clusters and their transfer to the target proteins. Co-localization of the protein to the apicoplast further provides an experimental evidence of a functional scaffold protein SufA for the biogenesis of Fe-S clusters in apicoplast of Plasmodium.

  8. A Plasmodium falciparum S33 proline aminopeptidase is associated with changes in erythrocyte deformability.

    PubMed

    da Silva, Fabio L; Dixon, Matthew W A; Stack, Colin M; Teuscher, Franka; Taran, Elena; Jones, Malcolm K; Lovas, Erica; Tilley, Leann; Brown, Christopher L; Trenholme, Katharine R; Dalton, John P; Gardiner, Donald L; Skinner-Adams, Tina S

    2016-10-01

    Infection with the apicomplexan parasite Plasmodium falciparum is a major cause of morbidity and mortality worldwide. One of the striking features of this parasite is its ability to remodel and decrease the deformability of host red blood cells, a process that contributes to disease. To further understand the virulence of Pf we investigated the biochemistry and function of a putative Pf S33 proline aminopeptidase (PfPAP). Unlike other P. falciparum aminopeptidases, PfPAP contains a predicted protein export element that is non-syntenic with other human infecting Plasmodium species. Characterization of PfPAP demonstrated that it is exported into the host red blood cell and that it is a prolyl aminopeptidase with a preference for N-terminal proline substrates. In addition genetic deletion of this exopeptidase was shown to lead to an increase in the deformability of parasite-infected red cells and in reduced adherence to the endothelial cell receptor CD36 under flow conditions. Our studies suggest that PfPAP plays a role in the rigidification and adhesion of infected red blood cells to endothelial surface receptors, a role that may make this protein a novel target for anti-disease interventions strategies.

  9. Whole Genome Sequencing of Field Isolates Reveals Extensive Genetic Diversity in Plasmodium vivax from Colombia

    PubMed Central

    Winter, David J.; Pacheco, M. Andreína; Vallejo, Andres F.; Schwartz, Rachel S.; Arevalo-Herrera, Myriam; Herrera, Socrates

    2015-01-01

    Plasmodium vivax is the most prevalent malarial species in South America and exerts a substantial burden on the populations it affects. The control and eventual elimination of P. vivax are global health priorities. Genomic research contributes to this objective by improving our understanding of the biology of P. vivax and through the development of new genetic markers that can be used to monitor efforts to reduce malaria transmission. Here we analyze whole-genome data from eight field samples from a region in Cordóba, Colombia where malaria is endemic. We find considerable genetic diversity within this population, a result that contrasts with earlier studies suggesting that P. vivax had limited diversity in the Americas. We also identify a selective sweep around a substitution known to confer resistance to sulphadoxine-pyrimethamine (SP). This is the first observation of a selective sweep for SP resistance in this species. These results indicate that P. vivax has been exposed to SP pressure even when the drug is not in use as a first line treatment for patients afflicted by this parasite. We identify multiple non-synonymous substitutions in three other genes known to be involved with drug resistance in Plasmodium species. Finally, we found extensive microsatellite polymorphisms. Using this information we developed 18 polymorphic and easy to score microsatellite loci that can be used in epidemiological investigations in South America. PMID:26709695

  10. Artesunate Tolerance in Transgenic Plasmodium falciparum Parasites Overexpressing a Tryptophan-Rich Protein▿†

    PubMed Central

    Deplaine, Guillaume; Lavazec, Catherine; Bischoff, Emmanuel; Natalang, Onguma; Perrot, Sylvie; Guillotte-Blisnick, Micheline; Coppée, Jean-Yves; Pradines, Bruno; Mercereau-Puijalon, Odile; David, Peter H.

    2011-01-01

    Due to their rapid, potent action on young and mature intraerythrocytic stages, artemisinin derivatives are central to drug combination therapies for Plasmodium falciparum malaria. However, the evidence for emerging parasite resistance/tolerance to artemisinins in southeast Asia is of great concern. A better understanding of artemisinin-related drug activity and resistance mechanisms is urgently needed. A recent transcriptome study of parasites exposed to artesunate led us to identify a series of genes with modified levels of expression in the presence of the drug. The gene presenting the largest mRNA level increase, Pf10_0026 (PArt), encoding a hypothetical protein of unknown function, was chosen for further study. Immunodetection with PArt-specific sera showed that artesunate induced a dose-dependent increase of the protein level. Bioinformatic analysis showed that PArt belongs to a Plasmodium-specific gene family characterized by the presence of a tryptophan-rich domain with a novel hidden Markov model (HMM) profile. Gene disruption could not be achieved, suggesting an essential function. Transgenic parasites overexpressing PArt protein were generated and exhibited tolerance to a spike exposure to high doses of artesunate, with increased survival and reduced growth retardation compared to that of wild-type-treated controls. These data indicate the involvement of PArt in parasite defense mechanisms against artesunate. This is the first report of genetically manipulated parasites displaying a stable and reproducible decreased susceptibility to artesunate, providing new possibilities to investigate the parasite response to artemisinins. PMID:21464256

  11. Effect of Farnesyltransferase Inhibitor R115777 on Mitochondria of Plasmodium falciparum.

    PubMed

    Ha, Young Ran; Hwang, Bae-Geun; Hong, Yeonchul; Yang, Hye-Won; Lee, Sang Joon

    2015-08-01

    The parasite Plasmodium falciparum causes severe malaria and is the most dangerous to humans. However, it exhibits resistance to their drugs. Farnesyltransferase has been identified in pathogenic protozoa of the genera Plasmodium and the target of farnesyltransferase includes Ras family. Therefore, the inhibition of farnesyltransferase has been suggested as a new strategy for the treatment of malaria. However, the exact functional mechanism of this agent is still unknown. In addition, the effect of farnesyltransferase inhibitor (FTIs) on mitochondrial level of malaria parasites is not fully understood. In this study, therefore, the effect of a FTI R115777 on the function of mitochondria of P. falciparum was investigated experimentally. As a result, FTI R115777 was found to suppress the infection rate of malaria parasites under in vitro condition. It also reduces the copy number of mtDNA-encoded cytochrome c oxidase III. In addition, the mitochondrial membrane potential (ΔΨm) and the green fluorescence intensity of MitoTracker were decreased by FTI R115777. Chloroquine and atovaquone were measured by the mtDNA copy number as mitochondrial non-specific or specific inhibitor, respectively. Chloroquine did not affect the copy number of mtDNA-encoded cytochrome c oxidase III, while atovaquone induced to change the mtDNA copy number. These results suggest that FTI R115777 has strong influence on the mitochondrial function of P. falciparum. It may have therapeutic potential for malaria by targeting the mitochondria of parasites.

  12. Characterization of Plasmodium developmental transcriptomes in Anopheles gambiae midgut reveals novel regulators of malaria transmission.

    PubMed

    Akinosoglou, Karolina A; Bushell, Ellen S C; Ukegbu, Chiamaka Valerie; Schlegelmilch, Timm; Cho, Jee-Sun; Redmond, Seth; Sala, Katarzyna; Christophides, George K; Vlachou, Dina

    2015-02-01

    The passage through the mosquito is a major bottleneck for malaria parasite populations and a target of interventions aiming to block disease transmission. Here, we used DNA microarrays to profile the developmental transcriptomes of the rodent malaria parasite Plasmodium berghei in vivo, in the midgut of Anopheles gambiae mosquitoes, from parasite stages in the midgut blood bolus to sporulating oocysts on the basal gut wall. Data analysis identified several distinct transcriptional programmes encompassing genes putatively involved in developmental processes or in interactions with the mosquito. At least two of these programmes are associated with the ookinete development that is linked to mosquito midgut invasion and establishment of infection. Targeted disruption by homologous recombination of two of these genes resulted in mutant parasites exhibiting notable infection phenotypes. GAMER encodes a short polypeptide with granular localization in the gametocyte cytoplasm and shows a highly penetrant loss-of-function phenotype manifested as greatly reduced ookinete numbers, linked to impaired male gamete release. HADO encodes a putative magnesium phosphatase with distinctive cortical localization along the concave ookinete periphery. Disruption of HADO compromises ookinete development leading to significant reduction of oocyst numbers. Our data provide important insights into the molecular framework underpinning Plasmodium development in the mosquito and identifies two genes with important functions at initial stages of parasite development in the mosquito midgut.

  13. Dynamics of molecular markers linked to the resistance loci in a mosquito-Plasmodium system.

    PubMed Central

    Yan, Guiyun; Severson, David W

    2003-01-01

    Models on the evolution of resistance to parasitism generally assume fitness tradeoffs between the costs of being parasitized and the costs associated with resistance. This study tested this assumption using the yellow fever mosquito Aedes aegypti and malaria parasite Plasmodium gallinaceum system. Experimental mosquito populations were created by mixing susceptible and resistant strains in equal proportions, and then the dynamics of markers linked to loci for Plasmodium resistance and other unlinked neutral markers were determined over 12 generations. We found that when the mixed population was maintained under parasite-free conditions, the frequencies of alleles specific to the susceptible strain at markers closely linked to the loci for resistance (QTL markers) as well as other unlinked markers increased significantly in the first generation and then fluctuated around equilibrium frequencies for all six markers. However, when the mixed population was exposed to an infected blood meal every generation, allele frequencies at the QTL markers for resistance were not significantly changed. Small population size caused significant random fluctuations of allele frequencies at all marker loci. Consistent allele frequency changes in the QTL markers and other unlinked markers suggest that the reduced fitness in the resistant population has a genome-wide effect on the genetic makeup of the mixed population. Continuous exposure to parasites promoted the maintenance of alleles from the resistant Moyo-R strain in the mixed population. The results are discussed in relation to the proposed malaria control strategy through genetic disruption of vector competence. PMID:12807772

  14. Whole Genome Sequencing of Field Isolates Reveals Extensive Genetic Diversity in Plasmodium vivax from Colombia.

    PubMed

    Winter, David J; Pacheco, M Andreína; Vallejo, Andres F; Schwartz, Rachel S; Arevalo-Herrera, Myriam; Herrera, Socrates; Cartwright, Reed A; Escalante, Ananias A

    2015-12-01

    Plasmodium vivax is the most prevalent malarial species in South America and exerts a substantial burden on the populations it affects. The control and eventual elimination of P. vivax are global health priorities. Genomic research contributes to this objective by improving our understanding of the biology of P. vivax and through the development of new genetic markers that can be used to monitor efforts to reduce malaria transmission. Here we analyze whole-genome data from eight field samples from a region in Cordóba, Colombia where malaria is endemic. We find considerable genetic diversity within this population, a result that contrasts with earlier studies suggesting that P. vivax had limited diversity in the Americas. We also identify a selective sweep around a substitution known to confer resistance to sulphadoxine-pyrimethamine (SP). This is the first observation of a selective sweep for SP resistance in this species. These results indicate that P. vivax has been exposed to SP pressure even when the drug is not in use as a first line treatment for patients afflicted by this parasite. We identify multiple non-synonymous substitutions in three other genes known to be involved with drug resistance in Plasmodium species. Finally, we found extensive microsatellite polymorphisms. Using this information we developed 18 polymorphic and easy to score microsatellite loci that can be used in epidemiological investigations in South America.

  15. A Plasmodium falciparum S33 proline aminopeptidase is associated with changes in erythrocyte deformability.

    PubMed

    da Silva, Fabio L; Dixon, Matthew W A; Stack, Colin M; Teuscher, Franka; Taran, Elena; Jones, Malcolm K; Lovas, Erica; Tilley, Leann; Brown, Christopher L; Trenholme, Katharine R; Dalton, John P; Gardiner, Donald L; Skinner-Adams, Tina S

    2016-10-01

    Infection with the apicomplexan parasite Plasmodium falciparum is a major cause of morbidity and mortality worldwide. One of the striking features of this parasite is its ability to remodel and decrease the deformability of host red blood cells, a process that contributes to disease. To further understand the virulence of Pf we investigated the biochemistry and function of a putative Pf S33 proline aminopeptidase (PfPAP). Unlike other P. falciparum aminopeptidases, PfPAP contains a predicted protein export element that is non-syntenic with other human infecting Plasmodium species. Characterization of PfPAP demonstrated that it is exported into the host red blood cell and that it is a prolyl aminopeptidase with a preference for N-terminal proline substrates. In addition genetic deletion of this exopeptidase was shown to lead to an increase in the deformability of parasite-infected red cells and in reduced adherence to the endothelial cell receptor CD36 under flow conditions. Our studies suggest that PfPAP plays a role in the rigidification and adhesion of infected red blood cells to endothelial surface receptors, a role that may make this protein a novel target for anti-disease interventions strategies. PMID:27373432

  16. Plasmodium falciparum and Plasmodium vivax specific lactate dehydrogenase: genetic polymorphism study from Indian isolates.

    PubMed

    Keluskar, Priyadarshan; Singh, Vineeta; Gupta, Purva; Ingle, Sanjay

    2014-08-01

    Control and eradication of malaria is hindered by the acquisition of drug resistance by Plasmodium species. This has necessitated a persistent search for novel drugs and more efficient targets. Plasmodium species specific lactate dehydrogenase is one of the potential therapeutic and diagnostic targets, because of its indispensable role in endoerythrocytic stage of the parasite. A target molecule that is highly conserved in the parasite population can be more effectively used in diagnostics and therapeutics, hence, in the present study polymorphism in PfLDH (Plasmodiumfalciparum specific LDH) and PvLDH (Plasmodiumvivax specific LDH) genes was analyzed using PCR-single strand confirmation polymorphism (PCR-SSCP) and sequencing. Forty-six P. falciparum and thirty-five P. vivax samples were screened from different states of India. Our findings have revealed presence of a single PfLDH genotype and six PvLDH genotypes among the studied samples. Interestingly, along with synonymous substitutions, nonsynonymous substitutions were reported to be present for the first time in the PvLDH genotypes. Further, through amino acid sequence alignment and homology modeling studies we observed that the catalytic residues were conserved in all PvLDH genotypes and the nonsynonymous substitutions have not altered the enzyme structure significantly. Evolutionary genetics studies have confirmed that PfLDH and PvLDH loci are under strong purifying selection. Phylogenetic analysis of the pLDH gene sequences revealed that P. falciparum compared to P. vivax, has recent origin. The study therefore supports PfLDH and PvLDH as suitable therapeutic and diagnostic targets as well as phylogenetic markers to understand the genealogy of malaria species.

  17. Genetic structure of Plasmodium vivax and Plasmodium falciparum in the Bannu district of Pakistan

    PubMed Central

    2010-01-01

    Background Plasmodium vivax and Plasmodium falciparum are the major causative agents of malaria. While knowledge of the genetic structure of malaria parasites is useful for understanding the evolution of parasite virulence, designing anti-malarial vaccines and assessing the impact of malaria control measures, there is a paucity of information on genetic diversity of these two malaria parasites in Pakistan. This study sought to shed some light on the genetic structure of P. vivax and P. falciparum in this understudied region. Methods The genetic diversities of P. vivax and P. falciparum populations from the densely populated, malaria-endemic Bannu district of Pakistan were evaluated by analysis of their merozoite surface protein (msp) genes by PCR-RFLP. Specifically, the Pvmsp-3α and Pvmsp-3β genes of P. vivax and the Pfmsp-1 and Pfmsp-2 genes of P. falciparum were analysed. Results In P. vivax, genotyping of Pvmsp-3α and Pvmsp-3β genes showed a high level of diversity at these loci. Four distinct allele groups: A (1.9 kb), B (1.5 kb), C (1.2 kb), and D (0.3 kb) were detected for Pvmsp-3α, type A being the most prevalent (82%). Conversely, amplification of the P. vivax msp-3β locus produced two allele groups: A (1.7-2.2 kb, 62%) and B (1.4-1.5 kb, 33%), with 5% mixed-strain infections. Restriction analysis of Pvmsp-3α and Pvmsp-3β yielded 12 and 8 distinct alleles, respectively, with a combined mixed genotype prevalence of 20%. In P. falciparum, all three known genotypes of Pfmsp-1 and two of Pfmsp-2 were observed, with MAD20 occurring in 67% and 3D7/IC in 65% of the isolates, respectively. Overall, 24% P. falciparum samples exhibited mixed-strain infections. Conclusion These results indicate that both P. vivax and P. falciparum populations in Pakistan are highly diverse. PMID:20416089

  18. In vitro activity of pyronaridine against multidrug-resistant Plasmodium falciparum and Plasmodium vivax.

    PubMed

    Price, R N; Marfurt, J; Chalfein, F; Kenangalem, E; Piera, K A; Tjitra, E; Anstey, N M; Russell, B

    2010-12-01

    Pyronaridine, a Mannich base antimalarial, has demonstrated high in vivo and in vitro efficacy against chloroquine-resistant Plasmodium falciparum. Although this drug has the potential to become a prominent artemisinin combination therapy, little is known about its efficacy against drug-resistant Plasmodium vivax. The in vitro antimalarial susceptibility of pyronaridine was assessed in multidrug-resistant P. vivax (n = 99) and P. falciparum (n = 90) isolates from Papua, Indonesia, using a schizont maturation assay. The median 50% inhibitory concentration (IC(50)) of pyronaridine was 1.92 nM (range, 0.24 to 13.8 nM) against P. falciparum and 2.58 nM (range, 0.13 to 43.6 nM) against P. vivax, with in vitro susceptibility correlating significantly with chloroquine, amodiaquine, and piperaquine (r(s) [Spearman's rank correlation coefficient] = 0.45 to 0.62; P < 0.001). P. falciparum parasites initially at trophozoite stage had higher IC(50)s of pyronaridine than those exposed at the ring stage (8.9 nM [range, 0.6 to 8.9 nM] versus 1.6 nM [range, 0.6 to 8.9 nM], respectively; P = 0.015), although this did not reach significance for P. vivax (4.7 nM [range, 1.4 to 18.7 nM] versus 2.5 nM [range, 1.4 to 15.6 nM], respectively; P = 0.085). The excellent in vitro efficacy of pyronaridine against both chloroquine-resistant P. vivax and P. falciparum highlights the suitability of the drug as a novel partner for artemisinin-based combination therapy in regions where the two species are coendemic.

  19. Plasmodium falciparum and Plasmodium vivax specific lactate dehydrogenase: genetic polymorphism study from Indian isolates.

    PubMed

    Keluskar, Priyadarshan; Singh, Vineeta; Gupta, Purva; Ingle, Sanjay

    2014-08-01

    Control and eradication of malaria is hindered by the acquisition of drug resistance by Plasmodium species. This has necessitated a persistent search for novel drugs and more efficient targets. Plasmodium species specific lactate dehydrogenase is one of the potential therapeutic and diagnostic targets, because of its indispensable role in endoerythrocytic stage of the parasite. A target molecule that is highly conserved in the parasite population can be more effectively used in diagnostics and therapeutics, hence, in the present study polymorphism in PfLDH (Plasmodiumfalciparum specific LDH) and PvLDH (Plasmodiumvivax specific LDH) genes was analyzed using PCR-single strand confirmation polymorphism (PCR-SSCP) and sequencing. Forty-six P. falciparum and thirty-five P. vivax samples were screened from different states of India. Our findings have revealed presence of a single PfLDH genotype and six PvLDH genotypes among the studied samples. Interestingly, along with synonymous substitutions, nonsynonymous substitutions were reported to be present for the first time in the PvLDH genotypes. Further, through amino acid sequence alignment and homology modeling studies we observed that the catalytic residues were conserved in all PvLDH genotypes and the nonsynonymous substitutions have not altered the enzyme structure significantly. Evolutionary genetics studies have confirmed that PfLDH and PvLDH loci are under strong purifying selection. Phylogenetic analysis of the pLDH gene sequences revealed that P. falciparum compared to P. vivax, has recent origin. The study therefore supports PfLDH and PvLDH as suitable therapeutic and diagnostic targets as well as phylogenetic markers to understand the genealogy of malaria species. PMID:24953504

  20. Pretreatment with Cry1Ac Protoxin Modulates the Immune Response, and Increases the Survival of Plasmodium-Infected CBA/Ca Mice

    PubMed Central

    Legorreta-Herrera, Martha; Oviedo Meza, Rodrigo; Moreno-Fierros, Leticia

    2010-01-01

    Malaria is a major global health problem that kills 1-2 million people each year. Despite exhaustive research, naturally acquired immunity is poorly understood. Cry1A proteins are potent immunogens with adjuvant properties and are able to induce strong cellular and humoral responses. In fact, it has been shown that administration of Cry1Ac protoxin alone or with amoebic lysates induces protection against the lethal infection caused by the protozoa Naegleria fowleri. In this work, we studied whether Cry1Ac is able to activate the innate immune response to induce protection against Plasmodium berghei ANKA (lethal) and P. chabaudi AS (nonlethal) parasites in CBA/Ca mice. Treatment with Cry1Ac induced protection against both Plasmodium species in terms of reduced parasitaemia, longer survival time, modulation of pro- and anti-inflammatory cytokines, and increased levels of specific antibodies against Plasmodium. Understanding how to boost innate immunity to Plasmodium infection should lead to immunologically based intervention strategies. PMID:20300584

  1. Origin of the human malaria parasite Plasmodium falciparum in gorillas.

    PubMed

    Liu, Weimin; Li, Yingying; Learn, Gerald H; Rudicell, Rebecca S; Robertson, Joel D; Keele, Brandon F; Ndjango, Jean-Bosco N; Sanz, Crickette M; Morgan, David B; Locatelli, Sabrina; Gonder, Mary K; Kranzusch, Philip J; Walsh, Peter D; Delaporte, Eric; Mpoudi-Ngole, Eitel; Georgiev, Alexander V; Muller, Martin N; Shaw, George M; Peeters, Martine; Sharp, Paul M; Rayner, Julian C; Hahn, Beatrice H

    2010-09-23

    Plasmodium falciparum is the most prevalent and lethal of the malaria parasites infecting humans, yet the origin and evolutionary history of this important pathogen remain controversial. Here we develop a single-genome amplification strategy to identify and characterize Plasmodium spp. DNA sequences in faecal samples from wild-living apes. Among nearly 3,000 specimens collected from field sites throughout central Africa, we found Plasmodium infection in chimpanzees (Pan troglodytes) and western gorillas (Gorilla gorilla), but not in eastern gorillas (Gorilla beringei) or bonobos (Pan paniscus). Ape plasmodial infections were highly prevalent, widely distributed and almost always made up of mixed parasite species. Analysis of more than 1,100 mitochondrial, apicoplast and nuclear gene sequences from chimpanzees and gorillas revealed that 99% grouped within one of six host-specific lineages representing distinct Plasmodium species within the subgenus Laverania. One of these from western gorillas comprised parasites that were nearly identical to P. falciparum. In phylogenetic analyses of full-length mitochondrial sequences, human P. falciparum formed a monophyletic lineage within the gorilla parasite radiation. These findings indicate that P. falciparum is of gorilla origin and not of chimpanzee, bonobo or ancient human origin.

  2. Structural Differences Explain Diverse Functions of Plasmodium Actins

    PubMed Central

    Vahokoski, Juha; Martinez, Silvia Muñico; Ignatev, Alexander; Lepper, Simone; Frischknecht, Friedrich; Sidén-Kiamos, Inga; Sachse, Carsten; Kursula, Inari

    2014-01-01

    Actins are highly conserved proteins and key players in central processes in all eukaryotic cells. The two actins of the malaria parasite are among the most divergent eukaryotic actins and also differ from each other more than isoforms in any other species. Microfilaments have not been directly observed in Plasmodium and are presumed to be short and highly dynamic. We show that actin I cannot complement actin II in male gametogenesis, suggesting critical structural differences. Cryo-EM reveals that Plasmodium actin I has a unique filament structure, whereas actin II filaments resemble canonical F-actin. Both Plasmodium actins hydrolyze ATP more efficiently than α-actin, and unlike any other actin, both parasite actins rapidly form short oligomers induced by ADP. Crystal structures of both isoforms pinpoint several structural changes in the monomers causing the unique polymerization properties. Inserting the canonical D-loop to Plasmodium actin I leads to the formation of long filaments in vitro. In vivo, this chimera restores gametogenesis in parasites lacking actin II, suggesting that stable filaments are required for exflagellation. Together, these data underline the divergence of eukaryotic actins and demonstrate how structural differences in the monomers translate into filaments with different properties, implying that even eukaryotic actins have faced different evolutionary pressures and followed different paths for developing their polymerization properties. PMID:24743229

  3. Plasmodium cellular effector mechanisms and the hepatic microenvironment

    PubMed Central

    Frevert, Ute; Krzych, Urszula

    2015-01-01

    Plasmodium falciparum malaria remains one of the most serious health problems globally. Immunization with attenuated parasites elicits multiple cellular effector mechanisms capable of eliminating Plasmodium liver stages. However, malaria liver stage (LS) immunity is complex and the mechanisms effector T cells use to locate the few infected hepatocytes in the large liver in order to kill the intracellular LS parasites remain a mystery to date. Here, we review our current knowledge on the behavior of CD8 effector T cells in the hepatic microvasculature, in malaria and other hepatic infections. Taking into account the unique immunological and lymphogenic properties of the liver, we discuss whether classical granule-mediated cytotoxicity might eliminate infected hepatocytes via direct cell contact or whether cytokines might operate without cell–cell contact and kill Plasmodium LSs at a distance. A thorough understanding of the cellular effector mechanisms that lead to parasite death hence sterile protection is a prerequisite for the development of a successful malaria vaccine to protect the 40% of the world’s population currently at risk of Plasmodium infection. PMID:26074888

  4. 21 CFR 866.3402 - Plasmodium species antigen detection assays.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 8 2014-04-01 2014-04-01 false Plasmodium species antigen detection assays. 866.3402 Section 866.3402 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES IMMUNOLOGY AND MICROBIOLOGY DEVICES Serological Reagents §...

  5. 21 CFR 866.3402 - Plasmodium species antigen detection assays.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 8 2011-04-01 2011-04-01 false Plasmodium species antigen detection assays. 866.3402 Section 866.3402 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES IMMUNOLOGY AND MICROBIOLOGY DEVICES Serological Reagents §...

  6. 21 CFR 866.3402 - Plasmodium species antigen detection assays.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 8 2012-04-01 2012-04-01 false Plasmodium species antigen detection assays. 866.3402 Section 866.3402 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES IMMUNOLOGY AND MICROBIOLOGY DEVICES Serological Reagents §...

  7. 21 CFR 866.3402 - Plasmodium species antigen detection assays.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Plasmodium species antigen detection assays. 866.3402 Section 866.3402 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES IMMUNOLOGY AND MICROBIOLOGY DEVICES Serological Reagents §...

  8. 21 CFR 866.3402 - Plasmodium species antigen detection assays.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 8 2013-04-01 2013-04-01 false Plasmodium species antigen detection assays. 866.3402 Section 866.3402 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES IMMUNOLOGY AND MICROBIOLOGY DEVICES Serological Reagents §...

  9. Origin of the human malaria parasite Plasmodium falciparum in gorillas

    PubMed Central

    Liu, Weimin; Li, Yingying; Learn, Gerald H.; Rudicell, Rebecca S.; Robertson, Joel D.; Keele, Brandon F.; Ndjango, Jean-Bosco N.; Sanz, Crickette M.; Morgan, David B.; Locatelli, Sabrina; Gonder, Mary K.; Kranzusch, Philip J.; Walsh, Peter D.; Delaporte, Eric; Mpoudi-Ngole, Eitel; Georgiev, Alexander V.; Muller, Martin N.; Shaw, George M.; Peeters, Martine; Sharp, Paul M.; Rayner, Julian C.; Hahn, Beatrice H.

    2010-01-01

    Plasmodium falciparum is the most prevalent and lethal of the malaria parasites infecting humans, yet the origin and evolutionary history of this important pathogen remain controversial. Here, we developed a novel polymerase chain reaction based single genome amplification strategy to identify and characterize Plasmodium spp. DNA sequences in fecal samples of wild-living apes. Among nearly 3,000 specimens collected from field sites throughout central Africa, we found Plasmodium infection in chimpanzees (Pan troglodytes) and western gorillas (Gorilla gorilla), but not in eastern gorillas (Gorilla beringei) or bonobos (Pan paniscus). Ape plasmodial infections were highly prevalent, widely distributed, and almost always comprised of mixed parasite species. Analysis of more than 1,100 mitochondrial, apicoplast and nuclear gene sequences from chimpanzees and gorillas revealed that 99% grouped within one of six host-specific lineages representing distinct Plasmodium species within the subgenus Laverania. One of these from western gorillas was comprised of parasites that were nearly identical to P. falciparum. In phylogenetic analyses of full-length mitochondrial sequences, human P. falciparum formed a monophyletic lineage within the gorilla parasite radiation. These findings indicate that P. falciparum is of gorilla and not of chimpanzee, bonobo or ancient human origin. PMID:20864995

  10. Dynamics of Plasmodium falciparum Parasitemia Regarding Combined Treatment Regimens for Acute Uncomplicated Malaria, Antioquia, Colombia

    PubMed Central

    Álvarez, Gonzalo; Tobón, Alberto; Piñeros, Juan-Gabriel; Ríos, Alexandra; Blair, Silvia

    2010-01-01

    Selecting suitable anti-malarial treatment represents one of the best tools for reducing morbidity and mortality caused by this disease. Sexual and asexual parasite dynamics were thus evaluated in patients involved in antimalarial drug efficacy studies by using combined treatment with and without artemisinin derivatives for treating uncomplicated acute Plasmodium falciparum malaria in Antioquia, Colombia. All treatment doses were supervised and administered according to patients' weight; sexual and asexual parasitemia were evaluated during 28- or 42-days follow-up in 468 patients. Artemisinin-based combination therapy showed greater parasiticidal ability, showing a mean asexual parasitemia survival rate of one day and mean gametocyte survival rate of 1–2 days. Sexual and asexual parasitemias were eliminated more quickly and effectively in the group receiving artemisinin-based combination therapy. Adding 45 mg of primaquine to treatment with artesunate and mefloquine reduced gametocyte and asexual parasite survival by one day. PMID:20595483

  11. Structure, Function and Inhibition of the Phosphoethanolamine Methyltransferases of the Human Malaria Parasites Plasmodium vivax and Plasmodium knowlesi

    SciTech Connect

    Garg, Aprajita; Lukk, Tiit; Kumar, Vidya; Choi, Jae-Yeon; Augagneur, Yoann; Voelker, Dennis R.; Nair, Satish; Mamoun, Choukri Ben

    2015-03-12

    Phosphoethanolamine methyltransferases (PMTs) catalyze the three-step methylation of phosphoethanolamine to form phosphocholine, a critical step in the synthesis of phosphatidylcholine in a select number of eukaryotes including human malaria parasites, nematodes and plants. Genetic studies in the malaria parasite Plasmodium falciparum have shown that the methyltransferase PfPMT plays a critical function in parasite development and differentiation. The presence of PMT orthologs in other malaria parasites that infect humans and their absence in mammals make them ideal targets for the development of selective antimalarials with broad specificity against different Plasmodium species. Here we describe the X-ray structures and biochemical properties of PMT orthologs from Plasmodium vivax and Plasmodium knowlesi and show that both enzymes are inhibited by amodiaquine and NSC158011, two drugs with potent antimalarial activity. Metabolic studies in a yeast mutant that relies on PkPMT or PvPMT for survival demonstrated that these compounds inhibit phosphatidylcholine biosynthesis from ethanolamine. Our structural and functional data provide insights into the mechanism of catalysis and inhibition of PMT enzymes and set the stage for a better design of more specific and selective antimalarial drugs.

  12. Structure, Function and Inhibition of the Phosphoethanolamine Methyltransferases of the Human Malaria Parasites Plasmodium vivax and Plasmodium knowlesi

    DOE PAGESBeta

    Garg, Aprajita; Lukk, Tiit; Kumar, Vidya; Choi, Jae-Yeon; Augagneur, Yoann; Voelker, Dennis R.; Nair, Satish; Mamoun, Choukri Ben

    2015-03-12

    Phosphoethanolamine methyltransferases (PMTs) catalyze the three-step methylation of phosphoethanolamine to form phosphocholine, a critical step in the synthesis of phosphatidylcholine in a select number of eukaryotes including human malaria parasites, nematodes and plants. Genetic studies in the malaria parasite Plasmodium falciparum have shown that the methyltransferase PfPMT plays a critical function in parasite development and differentiation. The presence of PMT orthologs in other malaria parasites that infect humans and their absence in mammals make them ideal targets for the development of selective antimalarials with broad specificity against different Plasmodium species. Here we describe the X-ray structures and biochemical properties ofmore » PMT orthologs from Plasmodium vivax and Plasmodium knowlesi and show that both enzymes are inhibited by amodiaquine and NSC158011, two drugs with potent antimalarial activity. Metabolic studies in a yeast mutant that relies on PkPMT or PvPMT for survival demonstrated that these compounds inhibit phosphatidylcholine biosynthesis from ethanolamine. Our structural and functional data provide insights into the mechanism of catalysis and inhibition of PMT enzymes and set the stage for a better design of more specific and selective antimalarial drugs.« less

  13. Structure, Function and Inhibition of the Phosphoethanolamine Methyltransferases of the Human Malaria Parasites Plasmodium vivax and Plasmodium knowlesi

    PubMed Central

    Garg, Aprajita; Lukk, Tiit; Kumar, Vidya; Choi, Jae-Yeon; Augagneur, Yoann; Voelker, Dennis R.; Nair, Satish; Mamoun, Choukri Ben

    2015-01-01

    Phosphoethanolamine methyltransferases (PMTs) catalyze the three-step methylation of phosphoethanolamine to form phosphocholine, a critical step in the synthesis of phosphatidylcholine in a select number of eukaryotes including human malaria parasites, nematodes and plants. Genetic studies in the malaria parasite Plasmodium falciparum have shown that the methyltransferase PfPMT plays a critical function in parasite development and differentiation. The presence of PMT orthologs in other malaria parasites that infect humans and their absence in mammals make them ideal targets for the development of selective antimalarials with broad specificity against different Plasmodium species. Here we describe the X-ray structures and biochemical properties of PMT orthologs from Plasmodium vivax and Plasmodium knowlesi and show that both enzymes are inhibited by amodiaquine and NSC158011, two drugs with potent antimalarial activity. Metabolic studies in a yeast mutant that relies on PkPMT or PvPMT for survival demonstrated that these compounds inhibit phosphatidylcholine biosynthesis from ethanolamine. Our structural and functional data provide insights into the mechanism of catalysis and inhibition of PMT enzymes and set the stage for a better design of more specific and selective antimalarial drugs. PMID:25761669

  14. Geographical variation in Plasmodium vivax relapse

    PubMed Central

    2014-01-01

    Background Plasmodium vivax has the widest geographic distribution of the human malaria parasites and nearly 2.5 billion people live at risk of infection. The control of P. vivax in individuals and populations is complicated by its ability to relapse weeks to months after initial infection. Strains of P. vivax from different geographical areas are thought to exhibit varied relapse timings. In tropical regions strains relapse quickly (three to six weeks), whereas those in temperate regions do so more slowly (six to twelve months), but no comprehensive assessment of evidence has been conducted. Here observed patterns of relapse periodicity are used to generate predictions of relapse incidence within geographic regions representative of varying parasite transmission. Methods A global review of reports of P. vivax relapse in patients not treated with a radical cure was conducted. Records of time to first P. vivax relapse were positioned by geographic origin relative to expert opinion regions of relapse behaviour and epidemiological zones. Mixed-effects meta-analysis was conducted to determine which geographic classification best described the data, such that a description of the pattern of relapse periodicity within each region could be described. Model outputs of incidence and mean time to relapse were mapped to illustrate the global variation in relapse. Results Differences in relapse periodicity were best described by a historical geographic classification system used to describe malaria transmission zones based on areas sharing zoological and ecological features. Maps of incidence and time to relapse showed high relapse frequency to be predominant in tropical regions and prolonged relapse in temperate areas. Conclusions The results indicate that relapse periodicity varies systematically by geographic region and are categorized by nine global regions characterized by similar malaria transmission dynamics. This indicates that relapse may be an adaptation evolved to

  15. In vivo and in vitro effectiveness of Azadirachta indica-synthesized silver nanocrystals against Plasmodium berghei and Plasmodium falciparum, and their potential against malaria mosquitoes.

    PubMed

    Murugan, Kadarkarai; Panneerselvam, Chellasamy; Samidoss, Christina Mary; Madhiyazhagan, Pari; Suresh, Udaiyan; Roni, Mathath; Chandramohan, Balamurugan; Subramaniam, Jayapal; Dinesh, Devakumar; Rajaganesh, Rajapandian; Paulpandi, Manickam; Wei, Hui; Aziz, Al Thabiani; Alsalhi, Mohamad Saleh; Devanesan, Sandhanasamy; Nicoletti, Marcello; Pavela, Roman; Canale, Angelo; Benelli, Giovanni

    2016-06-01

    Malaria transmission is a serious emergence in urban and semiurban areas worldwide, becoming a major international public health concern. Malaria is transmitted through the bites of Anopheles mosquitoes. The extensive employ of synthetic pesticides leads to negative effects on human health and the environment. Recently, plant-synthesized nanoparticles have been proposed as highly effective mosquitocides. In this research, we synthesized silver nanoparticles (AgNP) using the Azadirachta indica seed kernel extract as reducing and stabilizing agent. AgNP were characterized by UV-vis spectrophotometry, SEM, EDX, XRD and FTIR spectroscopy. The A. indica seed kernel extract was toxic against Anopheles stephensi larvae and pupae, LC50 were 232.8ppm (larva I), 260.6ppm (II), 290.3ppm (III), 323.4ppm (IV), and 348.4ppm (pupa). AgNP LC50 were 3.9ppm (I), 4.9ppm (II), 5.6ppm (III), 6.5ppm (IV), and 8.2ppm (pupa). The antiplasmodial activity of A. indica seed kernel extract and AgNP was evaluated against CQ-resistant (CQ-r) and CQ-sensitive (CQ-s) strains of Plasmodium falciparum. IC50 of A. indica seed kernel extract were 63.18μg/ml (CQ-s) and 69.24μg/ml (CQ-r). A. indica seed kernel-synthesized AgNP achieved IC50, of 82.41μg/ml (CQ-s) and 86.12μg/ml (CQ-r). However, in vivo anti-plasmodial experiments conducted on Plasmodium berghei infecting albino mice showed moderate activity of the A. indica extract and AgNP. Overall, this study showed that the A. indica-mediated fabrication of AgNP is of interest for a wide array of purposes, ranging from IPM of mosquito vectors to the development of novel and cheap antimalarial drugs.

  16. In vivo and in vitro effectiveness of Azadirachta indica-synthesized silver nanocrystals against Plasmodium berghei and Plasmodium falciparum, and their potential against malaria mosquitoes.

    PubMed

    Murugan, Kadarkarai; Panneerselvam, Chellasamy; Samidoss, Christina Mary; Madhiyazhagan, Pari; Suresh, Udaiyan; Roni, Mathath; Chandramohan, Balamurugan; Subramaniam, Jayapal; Dinesh, Devakumar; Rajaganesh, Rajapandian; Paulpandi, Manickam; Wei, Hui; Aziz, Al Thabiani; Alsalhi, Mohamad Saleh; Devanesan, Sandhanasamy; Nicoletti, Marcello; Pavela, Roman; Canale, Angelo; Benelli, Giovanni

    2016-06-01

    Malaria transmission is a serious emergence in urban and semiurban areas worldwide, becoming a major international public health concern. Malaria is transmitted through the bites of Anopheles mosquitoes. The extensive employ of synthetic pesticides leads to negative effects on human health and the environment. Recently, plant-synthesized nanoparticles have been proposed as highly effective mosquitocides. In this research, we synthesized silver nanoparticles (AgNP) using the Azadirachta indica seed kernel extract as reducing and stabilizing agent. AgNP were characterized by UV-vis spectrophotometry, SEM, EDX, XRD and FTIR spectroscopy. The A. indica seed kernel extract was toxic against Anopheles stephensi larvae and pupae, LC50 were 232.8ppm (larva I), 260.6ppm (II), 290.3ppm (III), 323.4ppm (IV), and 348.4ppm (pupa). AgNP LC50 were 3.9ppm (I), 4.9ppm (II), 5.6ppm (III), 6.5ppm (IV), and 8.2ppm (pupa). The antiplasmodial activity of A. indica seed kernel extract and AgNP was evaluated against CQ-resistant (CQ-r) and CQ-sensitive (CQ-s) strains of Plasmodium falciparum. IC50 of A. indica seed kernel extract were 63.18μg/ml (CQ-s) and 69.24μg/ml (CQ-r). A. indica seed kernel-synthesized AgNP achieved IC50, of 82.41μg/ml (CQ-s) and 86.12μg/ml (CQ-r). However, in vivo anti-plasmodial experiments conducted on Plasmodium berghei infecting albino mice showed moderate activity of the A. indica extract and AgNP. Overall, this study showed that the A. indica-mediated fabrication of AgNP is of interest for a wide array of purposes, ranging from IPM of mosquito vectors to the development of novel and cheap antimalarial drugs. PMID:27234530

  17. Thrombin Cleavage of Plasmodium falciparum Erythrocyte Membrane Protein 1 Inhibits Cytoadherence

    PubMed Central

    Gillrie, Mark R.; Renaux, Bernard; Russell-Goldman, Eleanor; Avril, Marion; Brazier, Andrew J.; Mihara, Koichiro; Di Cera, Enrico; Milner, Danny A.; Hollenberg, Morley D.; Smith, Joseph D.

    2016-01-01

    ABSTRACT Plasmodium falciparum malaria remains one of the most deadly infections worldwide. The pathogenesis of the infection results from the sequestration of infected erythrocytes (IRBC) in vital organs, including the brain, with resulting impairment of blood flow, hypoxia, and lactic acidosis. Sequestration occurs through the adhesion of IRBC to host receptors on microvascular endothelium by Plasmodium falciparum erythrocyte membrane protein 1 (PfEMP1), a large family of variant surface antigens, each with up to seven extracellular domains that can bind to multiple host receptors. Consequently, antiadhesive therapies directed at single endothelial adhesion molecules may not be effective. In this study, we demonstrated that the serine protease thrombin, which is pivotal in the activation of the coagulation cascade, cleaved the major parasite adhesin on the surface of IRBC. As a result, adhesion under flow was dramatically reduced, and already adherent IRBC were detached. Thrombin cleavage sites were mapped to the Duffy binding-like δ1 (DBLδ1) domain and interdomains 1 and 2 in the PfEMP1 of the parasite line IT4var19. Furthermore, we observed an inverse correlation between the presence of thrombin and IRBC in cerebral malaria autopsies of children. We investigated a modified (R67A) thrombin and thrombin inhibitor, hirugen, both of which inhibit the binding of substrates to exosite I, thereby reducing its proinflammatory properties. Both approaches reduced the barrier dysfunction induced by thrombin without affecting its proteolytic activity on PfEMP1, raising the possibility that thrombin cleavage of variant PfEMP1 may be exploited as a broadly inhibitory antiadhesive therapy. PMID:27624125

  18. Plasmodium spp. in raptors on the Eurasian-African migration route.

    PubMed

    Paperna, I; Yosef, R; Landau, I

    2007-12-01

    Examination of blood smears obtained from raptors trapped while on migration at Eilat, Israel, demonstrated Plasmodium infection in Accipiter brevipes and Buteo buteo. The following species are described, from A. brevipes: Plasmodium alloelongatum n. sp., P. accipiteris n. sp. and from B. buteo: P. buteonis n. sp. and Plasmodium sp. for which we lack sufficient data for adequate species description. Overall prevalence of infection with Plasmodium spp. was very low: among 38 examined A. brevipes 5% and among 56 B. buteo 3.6%.

  19. The MSPDBL2 codon 591 polymorphism is associated with lumefantrine in vitro drug responses in Plasmodium falciparum isolates from Kilifi, Kenya.

    PubMed

    Ochola-Oyier, Lynette Isabella; Okombo, John; Mwai, Leah; Kiara, Steven M; Pole, Lewa; Tetteh, Kevin K A; Nzila, Alexis; Marsh, Kevin

    2015-03-01

    The mechanisms of drug resistance development in the Plasmodium falciparum parasite to lumefantrine (LUM), commonly used in combination with artemisinin, are still unclear. We assessed the polymorphisms of Pfmspdbl2 for associations with LUM activity in a Kenyan population. MSPDBL2 codon 591S was associated with reduced susceptibility to LUM (P = 0.04). The high frequency of Pfmspdbl2 codon 591S in Kenya may be driven by the widespread use of lumefantrine in artemisinin combination therapy (Coartem). PMID:25534732

  20. The MSPDBL2 Codon 591 Polymorphism Is Associated with Lumefantrine In Vitro Drug Responses in Plasmodium falciparum Isolates from Kilifi, Kenya

    PubMed Central

    Okombo, John; Mwai, Leah; Kiara, Steven M.; Pole, Lewa; Tetteh, Kevin K. A.; Nzila, Alexis; Marsh, Kevin

    2014-01-01

    The mechanisms of drug resistance development in the Plasmodium falciparum parasite to lumefantrine (LUM), commonly used in combination with artemisinin, are still unclear. We assessed the polymorphisms of Pfmspdbl2 for associations with LUM activity in a Kenyan population. MSPDBL2 codon 591S was associated with reduced susceptibility to LUM (P = 0.04). The high frequency of Pfmspdbl2 codon 591S in Kenya may be driven by the widespread use of lumefantrine in artemisinin combination therapy (Coartem). PMID:25534732

  1. Effects of chronic avian malaria (Plasmodium relictum) infection on reproductive success of Hawaii Amakihi (Hemignathus virens)

    USGS Publications Warehouse

    Kilpatrick, A.M.; Lapointe, D.A.; Atkinson, C.T.; Woodworth, B.L.; Lease, J.K.; Reiter, M.E.; Gross, K.

    2006-01-01

    We studied the effects of chronic avian malaria (Plasmodium relictum) infections on the reproductive success of a native Hawaiian honeycreeper, Hawaii Amakihi (Hemignathus virens). Chronic malaria infections in male and female parents did not significantly reduce reproductive success as measured by clutch size, hatching success, fledging mass, number of nestlings fledged, nesting success (daily survival rate), and minimum fledgling survival. In fact, nesting success of pairs with chronically infected males was significantly higher than those with uninfected males (76% vs. 38%), and offspring that had at least one parent that had survived the acute phase of malaria infection had a significantly greater chance of being resighted the following year (25% vs. 10%). The reproduction and survival of infected birds were sufficient for a per-capita population growth rate >1, which suggests that chronically infected Hawaii Amakihi could support a growing population. ?? The American Ornithologists' Union, 2006.

  2. Wolbachia infections in natural Anopheles populations affect egg laying and negatively correlate with Plasmodium development

    PubMed Central

    Shaw, W. Robert; Marcenac, Perrine; Childs, Lauren M.; Buckee, Caroline O.; Baldini, Francesco; Sawadogo, Simon P.; Dabiré, Roch K.; Diabaté, Abdoulaye; Catteruccia, Flaminia

    2016-01-01

    The maternally inherited alpha-proteobacterium Wolbachia has been proposed as a tool to block transmission of devastating mosquito-borne infectious diseases like dengue and malaria. Here we study the reproductive manipulations induced by a recently identified Wolbachia strain that stably infects natural mosquito populations of a major malaria vector, Anopheles coluzzii, in Burkina Faso. We determine that these infections significantly accelerate egg laying but do not induce cytoplasmic incompatibility or sex-ratio distortion, two parasitic reproductive phenotypes that facilitate the spread of other Wolbachia strains within insect hosts. Analysis of 221 blood-fed A. coluzzii females collected from houses shows a negative correlation between the presence of Plasmodium parasites and Wolbachia infection. A mathematical model incorporating these results predicts that infection with these endosymbionts may reduce malaria prevalence in human populations. These data suggest that Wolbachia may be an important player in malaria transmission dynamics in Sub-Saharan Africa. PMID:27243367

  3. Large-scale growth of the Plasmodium falciparum malaria parasite in a wave bioreactor.

    PubMed

    Dalton, John P; Demanga, Corine G; Reiling, Sarah J; Wunderlich, Juliane; Eng, Jenny W L; Rohrbach, Petra

    2012-01-01

    We describe methods for the large-scale in vitro culturing of synchronous and asynchronous blood-stage Plasmodium falciparum parasites in sterile disposable plastic bioreactors controlled by wave-induced motion (wave bioreactor). These cultures perform better than static flask cultures in terms of preserving parasite cell cycle synchronicity and reducing the number of multiple-infected erythrocytes. The straight-forward methods described here will facilitate the large scale production of malaria parasites for antigen and organelle isolation and characterisation, for the high throughput screening of compound libraries with whole cells or extracts, and the development of live- or whole-cell malaria vaccines under good manufacturing practice compliant standards. PMID:22326740

  4. Nutritional requirements of Plasmodium falciparum in culture. I. Exogenously supplied dialyzable components necessary for continuous growth.

    PubMed

    Divo, A A; Geary, T G; Davis, N L; Jensen, J B

    1985-02-01

    Continuous cultivation of Plasmodium falciparum presently requires the nutritionally complex medium, RPMI 1640. A basal medium of KCl, NaCl, Na2HPO4, Ca(NO3)2, MgSO4, glucose, reduced glutathione, HEPES buffer, hypoxanthine, phenol red (in RPMI 1640 concentrations), and 10% (v/v) exhaustively dialyzed pooled human serum was used to determine which vitamins and amino acids had to be exogenously supplied for continuous cultivation. Supplementation of basal medium with calcium pantothenate, cystine, glutamate, glutamine, isoleucine, methionine, proline, and tyrosine was necessary for continuous growth. This semi-defined minimal medium supported continuous growth of four isolates of P. falciparum at rates slightly less than those obtained with RPMI 1640. Adding any other vitamin or amino acid did not improve growth. Incorporation of several non-essential amino acids, particularly phenylalanine and leucine, into proteins was markedly enhanced in the minimal medium compared to RPMI 1640. PMID:3886898

  5. Targeting of a Transporter to the Outer Apicoplast Membrane in the Human Malaria Parasite Plasmodium falciparum

    PubMed Central

    Goodman, Christopher D.; McFadden, Geoffrey I.

    2016-01-01

    Apicoplasts are vestigial plastids in apicomplexan parasites like Plasmodium, the causative agent of malaria. Apicomplexan parasites are dependant on their apicoplasts for synthesis of various molecules that they are unable to scavenge in sufficient quantity from their host, which makes apicoplasts attractive drug targets. Proteins known as plastid phosphate translocators (pPTs) are embedded in the outer apicoplast membrane and are responsible for the import of carbon, energy and reducing power to drive anabolic synthesis in the organelle. We investigated how a pPT is targeted into the outer apicoplast membrane of the human malaria parasite P. falciparum. We showed that a transmembrane domain is likely to act as a recessed signal anchor to direct the protein into the endomembrane system, and that a tyrosine in the cytosolic N-terminus of the protein is essential for targeting, but one or more, as yet unidentified, factors are also essential to direct the protein into the outer apicoplast membrane. PMID:27442138

  6. Drug resistance. K13-propeller mutations confer artemisinin resistance in Plasmodium falciparum clinical isolates.

    PubMed

    Straimer, Judith; Gnädig, Nina F; Witkowski, Benoit; Amaratunga, Chanaki; Duru, Valentine; Ramadani, Arba Pramundita; Dacheux, Mélanie; Khim, Nimol; Zhang, Lei; Lam, Stephen; Gregory, Philip D; Urnov, Fyodor D; Mercereau-Puijalon, Odile; Benoit-Vical, Françoise; Fairhurst, Rick M; Ménard, Didier; Fidock, David A

    2015-01-23

    The emergence of artemisinin resistance in Southeast Asia imperils efforts to reduce the global malaria burden. We genetically modified the Plasmodium falciparum K13 locus using zinc-finger nucleases and measured ring-stage survival rates after drug exposure in vitro; these rates correlate with parasite clearance half-lives in artemisinin-treated patients. With isolates from Cambodia, where resistance first emerged, survival rates decreased from 13 to 49% to 0.3 to 2.4% after the removal of K13 mutations. Conversely, survival rates in wild-type parasites increased from ≤0.6% to 2 to 29% after the insertion of K13 mutations. These mutations conferred elevated resistance to recent Cambodian isolates compared with that of reference lines, suggesting a contemporary contribution of additional genetic factors. Our data provide a conclusive rationale for worldwide K13-propeller sequencing to identify and eliminate artemisinin-resistant parasites.

  7. Targeting of a Transporter to the Outer Apicoplast Membrane in the Human Malaria Parasite Plasmodium falciparum.

    PubMed

    Lim, Liting; Sayers, Claire P; Goodman, Christopher D; McFadden, Geoffrey I

    2016-01-01

    Apicoplasts are vestigial plastids in apicomplexan parasites like Plasmodium, the causative agent of malaria. Apicomplexan parasites are dependant on their apicoplasts for synthesis of various molecules that they are unable to scavenge in sufficient quantity from their host, which makes apicoplasts attractive drug targets. Proteins known as plastid phosphate translocators (pPTs) are embedded in the outer apicoplast membrane and are responsible for the import of carbon, energy and reducing power to drive anabolic synthesis in the organelle. We investigated how a pPT is targeted into the outer apicoplast membrane of the human malaria parasite P. falciparum. We showed that a transmembrane domain is likely to act as a recessed signal anchor to direct the protein into the endomembrane system, and that a tyrosine in the cytosolic N-terminus of the protein is essential for targeting, but one or more, as yet unidentified, factors are also essential to direct the protein into the outer apicoplast membrane. PMID:27442138

  8. Drug resistance. K13-propeller mutations confer artemisinin resistance in Plasmodium falciparum clinical isolates.

    PubMed

    Straimer, Judith; Gnädig, Nina F; Witkowski, Benoit; Amaratunga, Chanaki; Duru, Valentine; Ramadani, Arba Pramundita; Dacheux, Mélanie; Khim, Nimol; Zhang, Lei; Lam, Stephen; Gregory, Philip D; Urnov, Fyodor D; Mercereau-Puijalon, Odile; Benoit-Vical, Françoise; Fairhurst, Rick M; Ménard, Didier; Fidock, David A

    2015-01-23

    The emergence of artemisinin resistance in Southeast Asia imperils efforts to reduce the global malaria burden. We genetically modified the Plasmodium falciparum K13 locus using zinc-finger nucleases and measured ring-stage survival rates after drug exposure in vitro; these rates correlate with parasite clearance half-lives in artemisinin-treated patients. With isolates from Cambodia, where resistance first emerged, survival rates decreased from 13 to 49% to 0.3 to 2.4% after the removal of K13 mutations. Conversely, survival rates in wild-type parasites increased from ≤0.6% to 2 to 29% after the insertion of K13 mutations. These mutations conferred elevated resistance to recent Cambodian isolates compared with that of reference lines, suggesting a contemporary contribution of additional genetic factors. Our data provide a conclusive rationale for worldwide K13-propeller sequencing to identify and eliminate artemisinin-resistant parasites. PMID:25502314

  9. Plasmodium cynomolgi genome sequences provide insight into Plasmodium vivax and the monkey malaria clade.

    PubMed

    Tachibana, Shin-Ichiro; Sullivan, Steven A; Kawai, Satoru; Nakamura, Shota; Kim, Hyunjae R; Goto, Naohisa; Arisue, Nobuko; Palacpac, Nirianne M Q; Honma, Hajime; Yagi, Masanori; Tougan, Takahiro; Katakai, Yuko; Kaneko, Osamu; Mita, Toshihiro; Kita, Kiyoshi; Yasutomi, Yasuhiro; Sutton, Patrick L; Shakhbatyan, Rimma; Horii, Toshihiro; Yasunaga, Teruo; Barnwell, John W; Escalante, Ananias A; Carlton, Jane M; Tanabe, Kazuyuki

    2012-09-01

    P. cynomolgi, a malaria-causing parasite of Asian Old World monkeys, is the sister taxon of P. vivax, the most prevalent malaria-causing species in humans outside of Africa. Because P. cynomolgi shares many phenotypic, biological and genetic characteristics with P. vivax, we generated draft genome sequences for three P. cynomolgi strains and performed genomic analysis comparing them with the P. vivax genome, as well as with the genome of a third previously sequenced simian parasite, Plasmodium knowlesi. Here, we show that genomes of the monkey malaria clade can be characterized by copy-number variants (CNVs) in multigene families involved in evasion of the human immune system and invasion of host erythrocytes. We identify genome-wide SNPs, microsatellites and CNVs in the P. cynomolgi genome, providing a map of genetic variation that can be used to map parasite traits and study parasite populations. The sequencing of the P. cynomolgi genome is a critical step in developing a model system for P. vivax research and in counteracting the neglect of P. vivax. PMID:22863735

  10. MOLECULAR SURVEILLANCE OF Plasmodium vivax AND Plasmodium falciparum DHFR MUTATIONS IN ISOLATES FROM SOUTHERN IRAN.

    PubMed

    Sharifi-Sarasiabi, Khojasteh; Haghighi, Ali; Kazemi, Bahram; Taghipour, Niloofar; Mojarad, Ehsan Nazemalhosseini; Gachkar, Latif

    2016-01-01

    In Iran, both Plasmodium vivax and P. falciparum malaria have been detected, but P. vivax is the predominant species. Point mutations in dihydrofolate reductase (dhfr) gene in both Plasmodia are the major mechanisms of pyrimethamine resistance. From April 2007 to June 2009, a total of 134 blood samples in two endemic areas of southern Iran were collected from patients infected with P. vivax and P. falciparum. The isolates were analyzed for P. vivax dihydrofolate reductase (pvdhfr) and P. falciparum dihydrofolate reductase (pfdhfr) point mutations using various PCR-based methods. The majority of the isolates (72.9%) had wild type amino acids at five codons of pvdhfr. Amongst mutant isolates, the most common pvdhfr alleles were double mutant in 58 and 117 amino acids (58R-117N). Triple mutation in 57, 58, and 117 amino acids (57L/58R/117N) was identified for the first time in the pvdhfr gene of Iranian P. vivax isolates. All the P. falciparumsamples analyzed (n = 16) possessed a double mutant pfdhfrallele (59R/108N) and retained a wild-type mutation at position 51. This may be attributed to the fact that the falciparum malaria patients were treated using sulfadoxine-pyrimethamine (SP) in Iran. The presence of mutant haplotypes in P. vivax is worrying, but has not yet reached an alarming threshold regarding drugs such as SP. The results of this study reinforce the importance of performing a molecular surveillance by means of a continuous chemoresistance assessment.

  11. Plasmodium cynomolgi genome sequences provide insight into Plasmodium vivax and the monkey malaria clade.

    PubMed

    Tachibana, Shin-Ichiro; Sullivan, Steven A; Kawai, Satoru; Nakamura, Shota; Kim, Hyunjae R; Goto, Naohisa; Arisue, Nobuko; Palacpac, Nirianne M Q; Honma, Hajime; Yagi, Masanori; Tougan, Takahiro; Katakai, Yuko; Kaneko, Osamu; Mita, Toshihiro; Kita, Kiyoshi; Yasutomi, Yasuhiro; Sutton, Patrick L; Shakhbatyan, Rimma; Horii, Toshihiro; Yasunaga, Teruo; Barnwell, John W; Escalante, Ananias A; Carlton, Jane M; Tanabe, Kazuyuki

    2012-09-01

    P. cynomolgi, a malaria-causing parasite of Asian Old World monkeys, is the sister taxon of P. vivax, the most prevalent malaria-causing species in humans outside of Africa. Because P. cynomolgi shares many phenotypic, biological and genetic characteristics with P. vivax, we generated draft genome sequences for three P. cynomolgi strains and performed genomic analysis comparing them with the P. vivax genome, as well as with the genome of a third previously sequenced simian parasite, Plasmodium knowlesi. Here, we show that genomes of the monkey malaria clade can be characterized by copy-number variants (CNVs) in multigene families involved in evasion of the human immune system and invasion of host erythrocytes. We identify genome-wide SNPs, microsatellites and CNVs in the P. cynomolgi genome, providing a map of genetic variation that can be used to map parasite traits and study parasite populations. The sequencing of the P. cynomolgi genome is a critical step in developing a model system for P. vivax research and in counteracting the neglect of P. vivax.

  12. Predictions of avian Plasmodium expansion under climate change

    PubMed Central

    Loiseau, Claire; Harrigan, Ryan J.; Bichet, Coraline; Julliard, Romain; Garnier, Stéphane; Lendvai, Ádám Z.; Chastel, Olivier; Sorci, Gabriele

    2013-01-01

    Vector-borne diseases are particularly responsive to changing environmental conditions. Diurnal temperature variation has been identified as a particularly important factor for the development of malaria parasites within vectors. Here, we conducted a survey across France, screening populations of the house sparrow (Passer domesticus) for malaria (Plasmodium relictum). We investigated whether variation in remotely-sensed environmental variables accounted for the spatial variation observed in prevalence and parasitemia. While prevalence was highly correlated to diurnal temperature range and other measures of temperature variation, environmental conditions could not predict spatial variation in parasitemia. Based on our empirical data, we mapped malaria distribution under climate change scenarios and predicted that Plasmodium occurrence will spread to regions in northern France, and that prevalence levels are likely to increase in locations where transmission already occurs. Our findings, based on remote sensing tools coupled with empirical data suggest that climatic change will significantly alter transmission of malaria parasites. PMID:23350033

  13. Imaging Plasmodium Immunobiology in Liver, Brain, and Lung

    PubMed Central

    Frevert, Ute; Nacer, Adéla; Cabrera, Mynthia; Movila, Alexandru; Leberl, Maike

    2013-01-01

    Plasmodium falciparum malaria is responsible for the deaths of over half a million African children annually. Until a decade ago, dynamic analysis of the malaria parasite was limited to in vitro systems with the typical limitations associated with 2D monocultures or entirely artificial surfaces. Due to extremely low parasite densities, the liver was considered a black box in terms of Plasmodium sporozoite invasion, liver stage development, and merozoite release into the blood. Further, nothing was known about the behavior of blood stage parasites in organs such as brain where clinical signs manifest and the ensuing immune response of the host that may ultimately result in a fatal outcome. The advent of fluorescent parasites, advances in imaging technology, and availability of an ever-increasing number of cellular and molecular probes have helped illuminate many steps along the pathogenetic cascade of this deadly tropical parasite. PMID:24076429

  14. Uncovering the transmission dynamics of Plasmodium vivax using population genetics.

    PubMed

    Barry, Alyssa E; Waltmann, Andreea; Koepfli, Cristian; Barnadas, Celine; Mueller, Ivo

    2015-05-01

    Population genetic analysis of malaria parasites has the power to reveal key insights into malaria epidemiology and transmission dynamics with the potential to deliver tools to support control and elimination efforts. Analyses of parasite genetic diversity have suggested that Plasmodium vivax populations are more genetically diverse and less structured than those of Plasmodium falciparum indicating that P. vivax may be a more ancient parasite of humans and/or less susceptible to population bottlenecks, as well as more efficient at disseminating its genes. These population genetic insights into P. vivax transmission dynamics provide an explanation for its relative resilience to control efforts. Here, we describe current knowledge on P. vivax population genetic structure, its relevance to understanding transmission patterns and relapse and how this information can inform malaria control and elimination programmes.

  15. [Plasmodium vivax, a parasite coming out of the shadows].

    PubMed

    Allgower, Andrea; Taylor, W Robert; Chappuis, François; Eperon, Gilles

    2016-05-01

    Since 2007, the incidence and mortality of malaria caused by Plasmodium falciparum have declined. However, this trend has not been seen with Plasmodium vivax which has biological features. Severe vivax malaria is increasingly reported in endemic countries even though P. vivax has been thought of as a benign disease. Diagnosis is challenging: the usual rapid diagnostic tests are less sensitive in detecting P. vivax and there is no test for the detection of the dormant forms (hypnozoites). The treatment of the acute phase is an artemisinin based combination, e.g. artemetherlumefantrine. Primaquine, which is the only currently available treatment against hypnozoites for the prevention of relapses, may trigger acute haemolytic anaemia in individuals with G6PD deficiency. PMID:27323480

  16. Host AMPK Is a Modulator of Plasmodium Liver Infection.

    PubMed

    Ruivo, Margarida T Grilo; Vera, Iset Medina; Sales-Dias, Joana; Meireles, Patrícia; Gural, Nil; Bhatia, Sangeeta N; Mota, Maria M; Mancio-Silva, Liliana

    2016-09-01

    Manipulation of the master regulator of energy homeostasis AMP-activated protein kinase (AMPK) activity is a strategy used by many intracellular pathogens for successful replication. Infection by most pathogens leads to an activation of host AMPK activity due to the energetic demands placed on the infected cell. Here, we demonstrate that the opposite is observed in cells infected with rodent malaria parasites. Indeed, AMPK activity upon the infection of hepatic cells is suppressed and dispensable for successful infection. By contrast, an overactive AMPK is deleterious to intracellular growth and replication of different Plasmodium spp., including the human malaria parasite, P. falciparum. The negative impact of host AMPK activity on infection was further confirmed in mice under conditions that activate its function. Overall, this work establishes the role of host AMPK signaling as a suppressive pathway of Plasmodium hepatic infection and as a potential target for host-based antimalarial interventions. PMID:27568570

  17. Uncovering the transmission dynamics of Plasmodium vivax using population genetics

    PubMed Central

    Barry, Alyssa E.; Waltmann, Andreea; Koepfli, Cristian; Barnadas, Celine; Mueller, Ivo

    2015-01-01

    Population genetic analysis of malaria parasites has the power to reveal key insights into malaria epidemiology and transmission dynamics with the potential to deliver tools to support control and elimination efforts. Analyses of parasite genetic diversity have suggested that Plasmodium vivax populations are more genetically diverse and less structured than those of Plasmodium falciparum indicating that P. vivax may be a more ancient parasite of humans and/or less susceptible to population bottlenecks, as well as more efficient at disseminating its genes. These population genetic insights into P. vivax transmission dynamics provide an explanation for its relative resilience to control efforts. Here, we describe current knowledge on P. vivax population genetic structure, its relevance to understanding transmission patterns and relapse and how this information can inform malaria control and elimination programmes. PMID:25891915

  18. [Plasmodium falciparum malaria: epidemiology and clinical features at Tarapoto Hospital].

    PubMed

    Calderon, J; Rodriguez, J; Romero, D

    1997-01-01

    A retrospective study was conducted of the clinical records of 41 patients discharged from a hospital in Tarapoto, Peru, between August 1992 and June 1996 following treatment for Plasmodium falciparum malaria. Patients ranged in age from 18 to 65 years; 25 were male. The cases were uniformly distributed throughout the year. The duration of illness averaged 11 days. At admission, 40 patients had fever, 36 had shaking chills, 29 had headache, 21 had nausea and vomiting, 21 had hyporexia, 15 had pallor, and 13 had splenomegaly. 3 of the 16 women were pregnant. 7 patients reported a history of malaria. The admission diagnosis was malaria in 33 cases. 31 patients were treated with chloroquine; 18 were subsequently treated with pyrimethamine-sulfadoxin and 1 received doxycycline. No cases of grave illness or death occurred. The increasing presence of Plasmodium falciparum malaria in the Peruvian lowlands should promote review of the adequacy of control programs.

  19. Structure of Plasmodium falciparum ADP-ribosylation factor 1

    SciTech Connect

    Cook, William J.; Smith, Craig D.; Senkovich, Olga; Holder, Anthony A.; Chattopadhyay, Debasish

    2011-09-26

    Vesicular trafficking may play a crucial role in the pathogenesis and survival of the malaria parasite. ADP-ribosylation factors (ARFs) are among the major components of vesicular trafficking pathways in eukaryotes. The crystal structure of ARF1 GTPase from Plasmodium falciparum has been determined in the GDP-bound conformation at 2.5 {angstrom} resolution and is compared with the structures of mammalian ARF1s.

  20. Subinoculation as a technique in the diagnosis of avian plasmodium

    USGS Publications Warehouse

    Herman, C.M.; Knisley, J.O.; Snyder, E.L.

    1966-01-01

    In two successive years, 1964 and 1965, blood subinoculated from wild Canada geese, negative for Plasmodium by examination of peripheral blood smears, into 5-day-old domestic geese produced 60 % infection in the recipients. Prepatent and patent periods, as well as intensity of parasitemia showed much variation. Intramuscular inoculation produced the same prevalence as the intravenous route, but longer prepatent periods and less intensity of parasitemia.

  1. CRISPR-mediated genome editing of Plasmodium falciparum malaria parasites.

    PubMed

    Lee, Marcus Cs; Fidock, David A

    2014-01-01

    The development of the CRISPR-Cas system is revolutionizing genome editing in a variety of organisms. The system has now been used to manipulate the genome of Plasmodium falciparum, the most lethal malaria-causing species. The ability to generate gene deletions or nucleotide substitutions rapidly and economically promises to accelerate the analysis of novel drug targets and to help elucidate the function of specific genes or gene families, while complementing genome-wide association studies.

  2. Plasmodium falciparum genetic crosses in a humanized mouse model

    PubMed Central

    Vaughan, Ashley M.; Pinapati, Richard S.; Cheeseman, Ian H.; Camargo, Nelly; Fishbaugher, Matthew; Checkley, Lisa A.; Nair, Shalini; Hutyra, Carolyn A.; Nosten, François H.; Anderson, Timothy J. C.; Ferdig, Michael T.; Kappe, Stefan H. I.

    2015-01-01

    Genetic crosses of phenotypically distinct strains of the human malaria parasite Plasmodium falciparum are a powerful tool for identifying genes controlling drug resistance and other key phenotypes. Previous studies relied on the isolation of recombinant parasites from splenectomized chimpanzees, a research avenue that is no longer available. Here, we demonstrate that human-liver chimeric mice support recovery of recombinant progeny for the identification of genetic determinants of parasite traits and adaptations. PMID:26030447

  3. Fatal Case of Plasmodium vivax Malaria in a Splenectomized Patient.

    PubMed

    Mahmoudvand, H; Farivar, L; Sharifi, I; Harandi, M Fasihi; Moazed, V; Jahanbakhsh, S; Babaei, Z; Zia-Ali, N

    2012-01-01

    Malaria is a major problem in tropical and sub-tropical countries, with high morbidity and mortality. Splenectomy makes patients more susceptible to serious bacterial and parasitic infections. We report for the first time in Iran a fatal case of Plasmodium vivax malaria, confirmed by microscopic and molecular (Semi-nested multiplex PCR) tests in a patient who had undergone splenectomy due to hemolytic anemia. PMID:23109969

  4. Fatal Case of Plasmodium vivax Malaria in a Splenectomized Patient

    PubMed Central

    Mahmoudvand, H; Farivar, L; Sharifi, I; Harandi, M Fasihi; Moazed, V; Jahanbakhsh, S; Babaei, Z; Zia-Ali, N

    2012-01-01

    Malaria is a major problem in tropical and sub-tropical countries, with high morbidity and mortality. Splenectomy makes patients more susceptible to serious bacterial and parasitic infections. We report for the first time in Iran a fatal case of Plasmodium vivax malaria, confirmed by microscopic and molecular (Semi-nested multiplex PCR) tests in a patient who had undergone splenectomy due to hemolytic anemia. PMID:23109969

  5. [A case of Plasmodium vivax malaria with findings of DIC].

    PubMed

    Takaki, K; Aoki, T; Akeda, H; Kajiwara, T; Honda, S; Maeda, Y; Okada, K; Sawae, Y

    1991-04-01

    We reported a rare case of Plasmodium vivax malaria who showed findings of disseminated intravascular coagulation (DIC). A 50-year-old Japanese male was sent to our hospital with the diagnosis of Plasmodium vivax malaria on the 26th of April, 1990. He had stayed in the Solomon Islands from Oct. 1987 to Dec. 1989, and had febrile episodes during his stay in the island. On April 18, 1990, he complained of a high fever with chills, and showed the same episodes on the 20th, 22th and was diagnosed as malaria. He was treated successfully with the sulfadoxine 500 mg and pyrimethamine 25mg (Fansidar), following the normal temperature on the 4th day and disappearance of malarial parasites in the peripheral blood smear on the 6th day. Interestingly, he had thrombocytopenia and a high titer serum level of fibrin degradation product (FDP) supporting the questionable diagnosis of DIC. Even on the 12th day after improved thrombocytopenia by treatment with Gabexate (FOY), the serum level of FDP, D-dimer and thrombin-nati-thrombin (TAT)III complex still remained at high titer levels. One month later he was readmitted for a relapse of Plasmodium vivax malaria, when he showed thrombocytopenia but the serum level of FDP, D-dimer, TAT III complex and PM.alpha 2 PI complex were normal levels. We concluded that the thrombocytopenia and the high titer of FDP at his first admission was a manifestation of DIC. PMID:2071964

  6. Targeting Plasmodium PI(4)K to eliminate malaria.

    PubMed

    McNamara, Case W; Lee, Marcus C S; Lim, Chek Shik; Lim, Siau Hoi; Roland, Jason; Nagle, Advait; Simon, Oliver; Yeung, Bryan K S; Chatterjee, Arnab K; McCormack, Susan L; Manary, Micah J; Zeeman, Anne-Marie; Dechering, Koen J; Kumar, T R Santha; Henrich, Philipp P; Gagaring, Kerstin; Ibanez, Maureen; Kato, Nobutaka; Kuhen, Kelli L; Fischli, Christoph; Rottmann, Matthias; Plouffe, David M; Bursulaya, Badry; Meister, Stephan; Rameh, Lucia; Trappe, Joerg; Haasen, Dorothea; Timmerman, Martijn; Sauerwein, Robert W; Suwanarusk, Rossarin; Russell, Bruce; Renia, Laurent; Nosten, Francois; Tully, David C; Kocken, Clemens H M; Glynne, Richard J; Bodenreider, Christophe; Fidock, David A; Diagana, Thierry T; Winzeler, Elizabeth A

    2013-12-12

    Achieving the goal of malaria elimination will depend on targeting Plasmodium pathways essential across all life stages. Here we identify a lipid kinase, phosphatidylinositol-4-OH kinase (PI(4)K), as the target of imidazopyrazines, a new antimalarial compound class that inhibits the intracellular development of multiple Plasmodium species at each stage of infection in the vertebrate host. Imidazopyrazines demonstrate potent preventive, therapeutic, and transmission-blocking activity in rodent malaria models, are active against blood-stage field isolates of the major human pathogens P. falciparum and P. vivax, and inhibit liver-stage hypnozoites in the simian parasite P. cynomolgi. We show that imidazopyrazines exert their effect through inhibitory interaction with the ATP-binding pocket of PI(4)K, altering the intracellular distribution of phosphatidylinositol-4-phosphate. Collectively, our data define PI(4)K as a key Plasmodium vulnerability, opening up new avenues of target-based discovery to identify drugs with an ideal activity profile for the prevention, treatment and elimination of malaria.

  7. Targeting Plasmodium PI(4)K to eliminate malaria.

    PubMed

    McNamara, Case W; Lee, Marcus C S; Lim, Chek Shik; Lim, Siau Hoi; Roland, Jason; Nagle, Advait; Simon, Oliver; Yeung, Bryan K S; Chatterjee, Arnab K; McCormack, Susan L; Manary, Micah J; Zeeman, Anne-Marie; Dechering, Koen J; Kumar, T R Santha; Henrich, Philipp P; Gagaring, Kerstin; Ibanez, Maureen; Kato, Nobutaka; Kuhen, Kelli L; Fischli, Christoph; Rottmann, Matthias; Plouffe, David M; Bursulaya, Badry; Meister, Stephan; Rameh, Lucia; Trappe, Joerg; Haasen, Dorothea; Timmerman, Martijn; Sauerwein, Robert W; Suwanarusk, Rossarin; Russell, Bruce; Renia, Laurent; Nosten, Francois; Tully, David C; Kocken, Clemens H M; Glynne, Richard J; Bodenreider, Christophe; Fidock, David A; Diagana, Thierry T; Winzeler, Elizabeth A

    2013-12-12

    Achieving the goal of malaria elimination will depend on targeting Plasmodium pathways essential across all life stages. Here we identify a lipid kinase, phosphatidylinositol-4-OH kinase (PI(4)K), as the target of imidazopyrazines, a new antimalarial compound class that inhibits the intracellular development of multiple Plasmodium species at each stage of infection in the vertebrate host. Imidazopyrazines demonstrate potent preventive, therapeutic, and transmission-blocking activity in rodent malaria models, are active against blood-stage field isolates of the major human pathogens P. falciparum and P. vivax, and inhibit liver-stage hypnozoites in the simian parasite P. cynomolgi. We show that imidazopyrazines exert their effect through inhibitory interaction with the ATP-binding pocket of PI(4)K, altering the intracellular distribution of phosphatidylinositol-4-phosphate. Collectively, our data define PI(4)K as a key Plasmodium vulnerability, opening up new avenues of target-based discovery to identify drugs with an ideal activity profile for the prevention, treatment and elimination of malaria. PMID:24284631

  8. Targeting Plasmodium PI(4)K to eliminate malaria

    NASA Astrophysics Data System (ADS)

    McNamara, Case W.; Lee, Marcus C. S.; Lim, Chek Shik; Lim, Siau Hoi; Roland, Jason; Nagle, Advait; Simon, Oliver; Yeung, Bryan K. S.; Chatterjee, Arnab K.; McCormack, Susan L.; Manary, Micah J.; Zeeman, Anne-Marie; Dechering, Koen J.; Kumar, T. R. Santha; Henrich, Philipp P.; Gagaring, Kerstin; Ibanez, Maureen; Kato, Nobutaka; Kuhen, Kelli L.; Fischli, Christoph; Rottmann, Matthias; Plouffe, David M.; Bursulaya, Badry; Meister, Stephan; Rameh, Lucia; Trappe, Joerg; Haasen, Dorothea; Timmerman, Martijn; Sauerwein, Robert W.; Suwanarusk, Rossarin; Russell, Bruce; Renia, Laurent; Nosten, Francois; Tully, David C.; Kocken, Clemens H. M.; Glynne, Richard J.; Bodenreider, Christophe; Fidock, David A.; Diagana, Thierry T.; Winzeler, Elizabeth A.

    2013-12-01

    Achieving the goal of malaria elimination will depend on targeting Plasmodium pathways essential across all life stages. Here we identify a lipid kinase, phosphatidylinositol-4-OH kinase (PI(4)K), as the target of imidazopyrazines, a new antimalarial compound class that inhibits the intracellular development of multiple Plasmodium species at each stage of infection in the vertebrate host. Imidazopyrazines demonstrate potent preventive, therapeutic, and transmission-blocking activity in rodent malaria models, are active against blood-stage field isolates of the major human pathogens P. falciparum and P. vivax, and inhibit liver-stage hypnozoites in the simian parasite P. cynomolgi. We show that imidazopyrazines exert their effect through inhibitory interaction with the ATP-binding pocket of PI(4)K, altering the intracellular distribution of phosphatidylinositol-4-phosphate. Collectively, our data define PI(4)K as a key Plasmodium vulnerability, opening up new avenues of target-based discovery to identify drugs with an ideal activity profile for the prevention, treatment and elimination of malaria.

  9. Rapid detection of Plasmodium falciparum with isothermal recombinase polymerase amplification and lateral flow analysis

    PubMed Central

    2014-01-01

    Background Nucleic acid amplification is the most sensitive and specific method to detect Plasmodium falciparum. However the polymerase chain reaction remains laboratory-based and has to be conducted by trained personnel. Furthermore, the power dependency for the thermocycling process and the costly equipment necessary for the read-out are difficult to cover in resource-limited settings. This study aims to develop and evaluate a combination of isothermal nucleic acid amplification and simple lateral flow dipstick detection of the malaria parasite for point-of-care testing. Methods A specific fragment of the 18S rRNA gene of P. falciparum was amplified in 10 min at a constant 38°C using the isothermal recombinase polymerase amplification (RPA) method. With a unique probe system added to the reaction solution, the amplification product can be visualized on a simple lateral flow strip without further labelling. The combination of these methods was tested for sensitivity and specificity with various Plasmodium and other protozoa/bacterial strains, as well as with human DNA. Additional investigations were conducted to analyse the temperature optimum, reaction speed and robustness of this assay. Results The lateral flow RPA (LF-RPA) assay exhibited a high sensitivity and specificity. Experiments confirmed a detection limit as low as 100 fg of genomic P. falciparum DNA, corresponding to a sensitivity of approximately four parasites per reaction. All investigated P. falciparum strains (n = 77) were positively tested while all of the total 11 non-Plasmodium samples, showed a negative test result. The enzymatic reaction can be conducted under a broad range of conditions from 30-45°C with high inhibitory concentration of known PCR inhibitors. A time to result of 15 min from start of the reaction to read-out was determined. Conclusions Combining the isothermal RPA and the lateral flow detection is an approach to improve molecular diagnostic for P. falciparum in

  10. A Small Molecule Glycosaminoglycan Mimetic Blocks Plasmodium Invasion of the Mosquito Midgut

    PubMed Central

    Ranucci, Elisabetta; Tao, Dingyin; Ferruti, Paolo; Ortega, Corrie; Staples, Gregory O.; Zaia, Joseph; Takashima, Eizo; Tsuboi, Takafumi; Borg, Natalie A.; Verotta, Luisella; Dinglasan, Rhoel R.

    2013-01-01

    Malaria transmission-blocking (T-B) interventions are essential for malaria elimination. Small molecules that inhibit the Plasmodium ookinete-to-oocyst transition in the midgut of Anopheles mosquitoes, thereby blocking sporogony, represent one approach to achieving this goal. Chondroitin sulfate glycosaminoglycans (CS-GAGs) on the Anopheles gambiae midgut surface are putative ligands for Plasmodium falciparum ookinetes. We hypothesized that our synthetic polysulfonated polymer, VS1, acting as a decoy molecular mimetic of midgut CS-GAGs confers malaria T-B activity. In our study, VS1 repeatedly reduced midgut oocyst development by as much as 99% (P<0.0001) in mosquitoes fed with P. falciparum and Plasmodium berghei. Through direct-binding assays, we observed that VS1 bound to two critical ookinete micronemal proteins, each containing at least one von Willebrand factor A (vWA) domain: (i) circumsporozoite protein and thrombospondin-related anonymous protein-related protein (CTRP) and (ii) vWA domain-related protein (WARP). By immunofluorescence microscopy, we observed that VS1 stains permeabilized P. falciparum and P. berghei ookinetes but does not stain P. berghei CTRP knockouts or transgenic parasites lacking the vWA domains of CTRP while retaining the thrombospondin repeat region. We produced structural homology models of the first vWA domain of CTRP and identified, as expected, putative GAG-binding sites on CTRP that align closely with those predicted for the human vWA A1 domain and the Toxoplasma gondii MIC2 adhesin. Importantly, the models also identified patches of electropositive residues that may extend CTRP's GAG-binding motif and thus potentiate VS1 binding. Our molecule binds to a critical, conserved ookinete protein, CTRP, and exhibits potent malaria T-B activity. This study lays the framework for a high-throughput screen of existing libraries of safe compounds to identify those with potent T-B activity. We envision that such compounds when used as

  11. Contrasting infection susceptibility of the Japanese macaques and cynomolgus macaques to closely related malaria parasites, Plasmodium vivax and Plasmodium cynomolgi.

    PubMed

    Tachibana, Shin-Ichiro; Kawai, Satoru; Katakai, Yuko; Takahashi, Hideo; Nakade, Toru; Yasutomi, Yasuhiro; Horii, Toshihiro; Tanabe, Kazuyuki

    2015-06-01

    Although the human malaria parasite Plasmodium vivax is closely related to Asian Old World monkey malaria parasites, there are no reports of P. vivax infections in macaques. In this study, we compared the infectivity of P. vivax and Plasmodium cynomolgi in Japanese macaques (Macaca fuscata) and in cynomolgus macaques (Macaca fascicularis). The Japanese macaques were highly susceptible to P. cynomolgi but not to P. vivax, whereas cynomolgus macaques showed mild/limited P. cynomolgi infection and were, also, not susceptible to P. vivax. Serotyping and amino acid sequence comparison of erythrocyte surface Duffy antigen/receptor for chemokines (DARC) indicate that the Japanese macaque DARC sequence is nearly identical to that of rhesus (Macaca mulatta) and cynomolgus macaques. This suggests that the macaques share a common mechanism for preventing P. vivax infection. Comparison of amino acid sequences of the Duffy-binding-like (DBL) domain from several different Plasmodium species suggests that P. vivax DBLs will not bind to macaque DARCs, which can explain the lack of P. vivax infectivity. The DBL sequence analyses also suggest that P. cynomolgi DBLs may target Japanese macaque erythrocytes through a DARC-independent interaction.

  12. Sequential Plasmodium chabaudi and Plasmodium berghei infections provide a novel model of severe malarial anemia.

    PubMed

    Harris, Juliana V; Bohr, Tiffany M; Stracener, Catherine; Landmesser, Mary E; Torres, Vladimir; Mbugua, Amos; Moratz, Chantal; Stoute, José A

    2012-09-01

    Lack of an adequate animal model of Plasmodium falciparum severe malarial anemia (SMA) has hampered the understanding of this highly lethal condition. We developed a model of SMA by infecting C57BL/6 mice with P. chabaudi followed after recovery by P. berghei infection. P. chabaudi/P. berghei-infected mice had an initial 9- to 10-day phase of relatively low parasitemia and severe anemia, followed by a second phase of hyperparasitemia, more profound anemia, reticulocytosis, and death 14 to 21 days after infection. P. chabaudi/P. berghei-infected animals had more intense splenic hematopoiesis, higher interleukin-10 (IL-10)/tumor necrosis factor alpha and IL-12/gamma interferon (IFN-γ) ratios, and higher antibody levels against P. berghei and P. chabaudi antigens than P. berghei-infected or P. chabaudi-recovered animals. Early treatment with chloroquine or artesunate did not prevent the anemia, suggesting that the bulk of red cell destruction was not due to the parasite. Red cells from P. chabaudi/P. berghei-infected animals had increased surface IgG and C3 by flow cytometry. However, C3(-/-) mice still developed anemia. Tracking of red cells labeled ex vivo and in vivo and analysis of frozen tissue sections by immunofluorescence microscopy showed that red cells from P. chabaudi/P. berghei-infected animals were removed at an accelerated rate in the liver by erythrophagocytosis. This model is practical and reproducible, and its similarities with P. falciparum SMA in humans makes it an appealing system with which to study the pathogenesis of this condition and explore potential immunomodulatory interventions.

  13. Human Plasmodium knowlesi Infection Detected by Rapid Diagnostic Tests for Malaria

    PubMed Central

    van Hellemond, Jaap J.; Rutten, Marijke; Koelewijn, Rob; Zeeman, Anne-Marie; Verweij, Jaco J.; Wismans, Pieter J.; Kocken, Clemens H.

    2009-01-01

    We describe a PCR-confirmed case of Plasmodium knowlesi infection with a high parasitemia level and clinical signs of severe malaria in a migrant worker from Malaysian Borneo in the Netherlands. Investigations showed that commercially available rapid antigen tests for detection of human Plasmodium infections can detect P. knowlesi infections in humans. PMID:19788819

  14. Frequency of pruritus in Plasmodium vivax malaria patients treated with chloroquine in Thailand.

    PubMed

    Bussaratid, V; Walsh, D S; Wilairatana, P; Krudsood, S; Silachamroon, U; Looareesuwan, S

    2000-10-01

    Chloroquine-induced itch in black-skinned African malaria patients is common and frequently leads to poor compliance or treatment defaulting.To assess the frequency and severity of chloroquine-induced pruritus in an Asian population, we reviewed case records of 1189 Plasmodium vivax malaria patients treated with chloroquine (25 mg/kg over 3 days) at the Bangkok Hospital for Tropical Diseases from 1992 through 1997. The majority of patients were Thais or ethnic Burmese (light brown skin), referred from the western border of Thailand. Overall, there were 23 patients (1.9%) with complaints of pruritus during chloroquine therapy. Of these, 12 (52%) had palm and sole involvement, eight (35%) had generalized pruritus including the palms and soles, and three (13%) had palm itching only. One patient developed pruritus on the palms and soles on two consecutive admissions. The pruritus did not interfere with daily activity, was reduced in intensity by anti-histamine therapy, and did not affect the patient's willingness to complete the chloroquine regimen. Therapeutic responses in the 23 patients with chloroquine itch was similar to those without itch. Among the itch patients, there was no association with gender or level of parasitaemias. Our findings indicate that the frequency of chloroquine-induced pruritus in Asian patients treated with chloroquine for P. vivax malaria is low in comparison with black-skinned Africans.This may be related to pharmacogenetic factors, the infective Plasmodium species, drug metabolism or drug-parasite interactions, or a lower affinity of chloroquine for less pigmented skin.

  15. Plasmodium knowlesi genome sequences from clinical isolates reveal extensive genomic dimorphism.

    PubMed

    Pinheiro, Miguel M; Ahmed, Md Atique; Millar, Scott B; Sanderson, Theo; Otto, Thomas D; Lu, Woon Chan; Krishna, Sanjeev; Rayner, Julian C; Cox-Singh, Janet

    2015-01-01

    Plasmodium knowlesi is a newly described zoonosis that causes malaria in the human population that can be severe and fatal. The study of P. knowlesi parasites from human clinical isolates is relatively new and, in order to obtain maximum information from patient sample collections, we explored the possibility of generating P. knowlesi genome sequences from archived clinical isolates. Our patient sample collection consisted of frozen whole blood samples that contained excessive human DNA contamination and, in that form, were not suitable for parasite genome sequencing. We developed a method to reduce the amount of human DNA in the thawed blood samples in preparation for high throughput parasite genome sequencing using Illumina HiSeq and MiSeq sequencing platforms. Seven of fifteen samples processed had sufficiently pure P. knowlesi DNA for whole genome sequencing. The reads were mapped to the P. knowlesi H strain reference genome and an average mapping of 90% was obtained. Genes with low coverage were removed leaving 4623 genes for subsequent analyses. Previously we identified a DNA sequence dimorphism on a small fragment of the P. knowlesi normocyte binding protein xa gene on chromosome 14. We used the genome data to assemble full-length Pknbpxa sequences and discovered that the dimorphism extended along the gene. An in-house algorithm was developed to detect SNP sites co-associating with the dimorphism. More than half of the P. knowlesi genome was dimorphic, involving genes on all chromosomes and suggesting that two distinct types of P. knowlesi infect the human population in Sarawak, Malaysian Borneo. We use P. knowlesi clinical samples to demonstrate that Plasmodium DNA from archived patient samples can produce high quality genome data. We show that analyses, of even small numbers of difficult clinical malaria isolates, can generate comprehensive genomic information that will improve our understanding of malaria parasite diversity and pathobiology.

  16. Erythrocytic Stage-dependent Regulation of Oligomerization of Plasmodium Ribosomal Protein P2*

    PubMed Central

    Das, Sudipta; Sudarsan, Rajagopal; Sivakami, Subramanian; Sharma, Shobhona

    2012-01-01

    The eukaryotic 60 S-ribosomal stalk consists of P0, P1, and P2 proteins, which associate in a pentameric structure (P12-P0-P22). The Plasmodium falciparum protein P2 (PfP2) appears to play nonribosomal roles. It gets exported to the infected erythrocyte (IE) surface at 30 h post-merozoite invasion (PMI), concomitant with extensive oligomerization. Here we present certain biophysical properties of PfP2. Recombinant P2 (rPfP2) protein showed SDS-resistant oligomerization, which could be significantly abolished under reducing conditions. However, the protein continued to oligomerize even when both cysteine residues were mutated, and with up to 40 amino acids (aa) deleted from the C-terminal end. CD analysis of P2 showed largely α-helical and random coil domains. The SDS- and DTT-resistant oligomerization was studied further as it occurred in a development-specific manner in Plasmodium. In a synchronized erythrocytic culture of P. falciparum, the PfP2 protein was detected as part of the ribosomal complex (∼96 kDa) at 18 and 30 h PMI, and was SDS sensitive. However, at 30 h, large amounts of SDS-sensitive aggregates of >600 kDa were also seen. At 30 h PMI, each of the parasites, IE cytosol and IE ghost contained 60–80-kDa PfP2 complexes, which resolved to a single 65-kDa species on SDS-PAGE. Tetramethylrhodamine-labeled rPfP2 protein exhibited DTT- and SDS-resistant oligomerization when treated with P. falciparum parasite extracts only from 24 to 36 h PMI, and multiple proteins appeared to be required for this oligomerization. Understanding the regulation of oligomerization of PfP2 may help in the elucidation of the novel structure-function relationship in the export of PfP2 to the red cell surface. PMID:23060439

  17. Killer Bee Molecules: Antimicrobial Peptides as Effector Molecules to Target Sporogonic Stages of Plasmodium

    PubMed Central

    Carter, Victoria; Underhill, Ann; Baber, Ibrahima; Sylla, Lakamy; Baby, Mounirou; Larget-Thiery, Isabelle; Zettor, Agnès; Bourgouin, Catherine; Langel, Ülo; Faye, Ingrid; Otvos, Laszlo; Wade, John D.; Coulibaly, Mamadou B.; Traore, Sekou F.; Tripet, Frederic; Eggleston, Paul; Hurd, Hilary

    2013-01-01

    A new generation of strategies is evolving that aim to block malaria transmission by employing genetically modified vectors or mosquito pathogens or symbionts that express anti-parasite molecules. Whilst transgenic technologies have advanced rapidly, there is still a paucity of effector molecules with potent anti-malaria activity whose expression does not cause detrimental effects on mosquito fitness. Our objective was to examine a wide range of antimicrobial peptides (AMPs) for their toxic effects on Plasmodium and anopheline mosquitoes. Specifically targeting early sporogonic stages, we initially screened AMPs for toxicity against a mosquito cell line and P. berghei ookinetes. Promising candidate AMPs were fed to mosquitoes to monitor adverse fitness effects, and their efficacy in blocking rodent malaria infection in Anopheles stephensi was assessed. This was followed by tests to determine their activity against P. falciparum in An. gambiae, initially using laboratory cultures to infect mosquitoes, then culminating in preliminary assays in the field using gametocytes and mosquitoes collected from the same area in Mali, West Africa. From a range of 33 molecules, six AMPs able to block Plasmodium development were identified: Anoplin, Duramycin, Mastoparan X, Melittin, TP10 and Vida3. With the exception of Anoplin and Mastoparan X, these AMPs were also toxic to an An. gambiae cell line at a concentration of 25 µM. However, when tested in mosquito blood feeds, they did not reduce mosquito longevity or egg production at concentrations of 50 µM. Peptides effective against cultured ookinetes were less effective when tested in vivo and differences in efficacy against P. berghei and P. falciparum were seen. From the range of molecules tested, the majority of effective AMPs were derived from bee/wasp venoms. PMID:24278025

  18. Plasmodium berghei mouse model: antimalarial activity of new alkaloid salts and of thiosemicarbazone and acridine derivatives.

    PubMed

    Loiseau, P M; Nguyen, D X

    1996-06-01

    Sixteen compounds were synthesized and evaluated on Plasmodium berghei in CD1 mouse. The nature of the salt associated to the active principle can give some advantages in the field of activity, bioavailability and toxicity. beta-Resorcylic acid was chosen in this study because of its previously described antimalarial activity and its expected enhancement of quinine antimalarial activity. While treatment with subcutaneous quinine sulphate at 1 mmol/kg cured 6/10 mice, quinine beta-resorcylate cured all the mice under identical conditions. Although such a result appeared promising, in vitro investigation should be performed to draw clear conclusions regarding a synergy between quinine and beta-resorcylate. Cinchonidine beta-resorcylate was also active; all mice were cured at 1 mmol/kg and the mean survival time was 13.8 +/- 2.4 days after a subcutaneous treatment at 0.5 mmol/kg in a single dose. In the series of acridines, (N-alpha, sigma-dioxopentyl)-5-amino-1,2,3,4-tetrahydroacridine cured all mice at 50 mumol/kg under the same conditions. The maximum tolerated doses in mice ranged from 100 to 150 mumol/kg for these acridine derivatives. The chemotherapeutic index of (N-alpha, sigma-dioxopentyl)-5-amino-1,2,3,4-tetrahydroacridine was estimated at 2-3. Other salts expected to reduce the toxicity, such as alpha-ketoglutarate and p-chlorophenoxyacetate, did not enhance the activity of the active principles. These results prompt us to further investigations including plasma kinetic evaluation in rats and in vitro on Plasmodium falciparum.

  19. A Plasmodium falciparum copper-binding membrane protein with copper transport motifs

    PubMed Central

    2012-01-01

    Background Copper is an essential catalytic co-factor for metabolically important cellular enzymes, such as cytochrome-c oxidase. Eukaryotic cells acquire copper through a copper transport protein and distribute intracellular copper using molecular chaperones. The copper chelator, neocuproine, inhibits Plasmodium falciparum ring-to-trophozoite transition in vitro, indicating a copper requirement for malaria parasite development. How the malaria parasite acquires or secretes copper still remains to be fully elucidated. Methods PlasmoDB was searched for sequences corresponding to candidate P. falciparum copper-requiring proteins. The amino terminal domain of a putative P. falciparum copper transport protein was cloned and expressed as a maltose binding fusion protein. The copper binding ability of this protein was examined. Copper transport protein-specific anti-peptide antibodies were generated in chickens and used to establish native protein localization in P. falciparum parasites by immunofluorescence microscopy. Results Six P. falciparum copper-requiring protein orthologs and a candidate P. falciparum copper transport protein (PF14_0369), containing characteristic copper transport protein features, were identified in PlasmoDB. The recombinant amino terminal domain of the transport protein bound reduced copper in vitro and within Escherichia coli cells during recombinant expression. Immunolocalization studies tracked the copper binding protein translocating from the erythrocyte plasma membrane in early ring stage to a parasite membrane as the parasites developed to schizonts. The protein appears to be a PEXEL-negative membrane protein. Conclusion Plasmodium falciparum parasites express a native protein with copper transporter characteristics that binds copper in vitro. Localization of the protein to the erythrocyte and parasite plasma membranes could provide a mechanism for the delivery of novel anti-malarial compounds. PMID:23190769

  20. Loop-Mediated Isothermal Amplification Assay for Identification of Five Human Plasmodium Species in Malaysia.

    PubMed

    Lau, Yee-Ling; Lai, Meng-Yee; Fong, Mun-Yik; Jelip, Jenarun; Mahmud, Rohela

    2016-02-01

    The lack of rapid, affordable, and accurate diagnostic tests represents the primary hurdle affecting malaria surveillance in resource- and expertise-limited areas. Loop-mediated isothermal amplification (LAMP) is a sensitive, rapid, and cheap diagnostic method. Five species-specific LAMP assays were developed based on 18S rRNA gene. Sensitivity and specificity of LAMP results were calculated as compared with microscopic examination and nested polymerase chain reaction. LAMP reactions were highly sensitive with the detection limit of one copy for Plasmodium vivax, Plasmodium falciparum, and Plasmodium malariae and 10 copies for Plasmodium knowlesi and Plasmodium ovale. LAMP positively detected all human malaria species in all positive samples (N = 134; sensitivity = 100%) within 35 minutes. All negative samples were not amplified by LAMP (N = 67; specificity = 100%). LAMP successfully detected two samples with very low parasitemia. LAMP may offer a rapid, simple, and reliable test for the diagnosis of malaria in areas where malaria is prevalent.

  1. Transmission blocking potency and immunogenicity of a plant-produced Pvs25-based subunit vaccine against Plasmodium vivax.

    PubMed

    Blagborough, A M; Musiychuk, K; Bi, H; Jones, R M; Chichester, J A; Streatfield, S; Sala, K A; Zakutansky, S E; Upton, L M; Sinden, R E; Brian, I; Biswas, S; Sattabonkot, J; Yusibov, V

    2016-06-14

    Malaria transmission blocking (TB) vaccines (TBVs) directed against proteins expressed on the sexual stages of Plasmodium parasites are a potentially effective means to reduce transmission. Antibodies induced by TBVs block parasite development in the mosquito, and thus inhibit transmission to further human hosts. The ookinete surface protein P25 is a primary target for TBV development. Recently, transient expression in plants using hybrid viral vectors has demonstrated potential as a strategy for cost-effective and scalable production of recombinant vaccines. Using a plant virus-based expression system, we produced recombinant P25 protein of Plasmodium vivax (Pvs25) in Nicotiana benthamiana fused to a modified lichenase carrier protein. This candidate vaccine, Pvs25-FhCMB, was purified, characterized and evaluated for immunogenicity and efficacy using multiple adjuvants in a transgenic rodent model. An in vivo TB effect of up to a 65% reduction in intensity and 54% reduction in prevalence was observed using Abisco-100 adjuvant. The ability of this immunogen to induce a TB response was additionally combined with heterologous prime-boost vaccination with viral vectors expressing Pvs25. Significant blockade was observed when combining both platforms, achieving a 74% and 68% reduction in intensity and prevalence, respectively. This observation was confirmed by direct membrane feeding on field P. vivax samples, resulting in reductions in intensity/prevalence of 85.3% and 25.5%. These data demonstrate the potential of this vaccine candidate and support the feasibility of expressing Plasmodium antigens in a plant-based system for the production of TBVs, while demonstrating the potential advantages of combining multiple vaccine delivery systems to maximize efficacy.

  2. Transmission blocking potency and immunogenicity of a plant-produced Pvs25-based subunit vaccine against Plasmodium vivax.

    PubMed

    Blagborough, A M; Musiychuk, K; Bi, H; Jones, R M; Chichester, J A; Streatfield, S; Sala, K A; Zakutansky, S E; Upton, L M; Sinden, R E; Brian, I; Biswas, S; Sattabonkot, J; Yusibov, V

    2016-06-14

    Malaria transmission blocking (TB) vaccines (TBVs) directed against proteins expressed on the sexual stages of Plasmodium parasites are a potentially effective means to reduce transmission. Antibodies induced by TBVs block parasite development in the mosquito, and thus inhibit transmission to further human hosts. The ookinete surface protein P25 is a primary target for TBV development. Recently, transient expression in plants using hybrid viral vectors has demonstrated potential as a strategy for cost-effective and scalable production of recombinant vaccines. Using a plant virus-based expression system, we produced recombinant P25 protein of Plasmodium vivax (Pvs25) in Nicotiana benthamiana fused to a modified lichenase carrier protein. This candidate vaccine, Pvs25-FhCMB, was purified, characterized and evaluated for immunogenicity and efficacy using multiple adjuvants in a transgenic rodent model. An in vivo TB effect of up to a 65% reduction in intensity and 54% reduction in prevalence was observed using Abisco-100 adjuvant. The ability of this immunogen to induce a TB response was additionally combined with heterologous prime-boost vaccination with viral vectors expressing Pvs25. Significant blockade was observed when combining both platforms, achieving a 74% and 68% reduction in intensity and prevalence, respectively. This observation was confirmed by direct membrane feeding on field P. vivax samples, resulting in reductions in intensity/prevalence of 85.3% and 25.5%. These data demonstrate the potential of this vaccine candidate and support the feasibility of expressing Plasmodium antigens in a plant-based system for the production of TBVs, while demonstrating the potential advantages of combining multiple vaccine delivery systems to maximize efficacy. PMID:27177945

  3. Evaluation of the Sensitivity of a pLDH-Based and an Aldolase-Based Rapid Diagnostic Test for Diagnosis of Uncomplicated and Severe Malaria Caused by PCR-Confirmed Plasmodium knowlesi, Plasmodium falciparum, and Plasmodium vivax

    PubMed Central

    William, Timothy; Grigg, Matthew J.; Piera, Kim; Yeo, Tsin W.; Anstey, Nicholas M.

    2013-01-01

    Plasmodium knowlesi can cause severe and fatal human malaria in Southeast Asia. Rapid diagnosis of all Plasmodium species is essential for initiation of effective treatment. Rapid diagnostic tests (RDTs) are sensitive for detection of uncomplicated and severe falciparum malaria but have not been systematically evaluated in knowlesi malaria. At a tertiary referral hospital in Sabah, Malaysia, we prospectively evaluated the sensitivity of two combination RDTs for the diagnosis of uncomplicated and severe malaria from all three potentially fatal Plasmodium species, using a pan-Plasmodium lactate dehydrogenase (pLDH)-P. falciparum histidine-rich protein 2 (PfHRP2) RDT (First Response) and a pan-Plasmodium aldolase-PfHRP2 RDT (ParaHIT). Among 293 hospitalized adults with PCR-confirmed Plasmodium monoinfection, the sensitivity of the pLDH component of the pLDH-PfHRP2 RDT was 74% (95/129; 95% confidence interval [CI], 65 to 80%), 91% (110/121; 95% CI, 84 to 95%), and 95% (41/43; 95% CI, 85 to 99%) for PCR-confirmed P. knowlesi, P. falciparum, and P. vivax infections, respectively, and 88% (30/34; 95% CI, 73 to 95%), 90% (38/42; 95% CI, 78 to 96%), and 100% (12/12; 95% CI, 76 to 100%) among patients tested before antimalarial treatment was begun. Sensitivity in severe malaria was 95% (36/38; 95% CI, 83 to 99), 100% (13/13; 95% CI, 77 to 100), and 100% (7/7; 95% CI, 65 to 100%), respectively. The aldolase component of the aldolase-PfHRP2 RDT performed poorly in all Plasmodium species. The pLDH-based RDT was highly sensitive for the diagnosis of severe malaria from all species; however, neither the pLDH- nor aldolase-based RDT demonstrated sufficiently high overall sensitivity for P. knowlesi. More sensitive RDTs are needed in regions of P. knowlesi endemicity. PMID:23345297

  4. Evaluation of the sensitivity of a pLDH-based and an aldolase-based rapid diagnostic test for diagnosis of uncomplicated and severe malaria caused by PCR-confirmed Plasmodium knowlesi, Plasmodium falciparum, and Plasmodium vivax.

    PubMed

    Barber, Bridget E; William, Timothy; Grigg, Matthew J; Piera, Kim; Yeo, Tsin W; Anstey, Nicholas M

    2013-04-01

    Plasmodium knowlesi can cause severe and fatal human malaria in Southeast Asia. Rapid diagnosis of all Plasmodium species is essential for initiation of effective treatment. Rapid diagnostic tests (RDTs) are sensitive for detection of uncomplicated and severe falciparum malaria but have not been systematically evaluated in knowlesi malaria. At a tertiary referral hospital in Sabah, Malaysia, we prospectively evaluated the sensitivity of two combination RDTs for the diagnosis of uncomplicated and severe malaria from all three potentially fatal Plasmodium species, using a pan-Plasmodium lactate dehydrogenase (pLDH)-P. falciparum histidine-rich protein 2 (PfHRP2) RDT (First Response) and a pan-Plasmodium aldolase-PfHRP2 RDT (ParaHIT). Among 293 hospitalized adults with PCR-confirmed Plasmodium monoinfection, the sensitivity of the pLDH component of the pLDH-PfHRP2 RDT was 74% (95/129; 95% confidence interval [CI], 65 to 80%), 91% (110/121; 95% CI, 84 to 95%), and 95% (41/43; 95% CI, 85 to 99%) for PCR-confirmed P. knowlesi, P. falciparum, and P. vivax infections, respectively, and 88% (30/34; 95% CI, 73 to 95%), 90% (38/42; 95% CI, 78 to 96%), and 100% (12/12; 95% CI, 76 to 100%) among patients tested before antimalarial treatment was begun. Sensitivity in severe malaria was 95% (36/38; 95% CI, 83 to 99), 100% (13/13; 95% CI, 77 to 100), and 100% (7/7; 95% CI, 65 to 100%), respectively. The aldolase component of the aldolase-PfHRP2 RDT performed poorly in all Plasmodium species. The pLDH-based RDT was highly sensitive for the diagnosis of severe malaria from all species; however, neither the pLDH- nor aldolase-based RDT demonstrated sufficiently high overall sensitivity for P. knowlesi. More sensitive RDTs are needed in regions of P. knowlesi endemicity.

  5. [Monkey malaria (Plasmodium knowlesi infection) after travelling to Thailand].

    PubMed

    Kroidl, Inge; Seilmaier, Michael; Berens-Riha, Nicole; Bretzel, Gisela; Wendtner, Clemens; Löscher, Thomas

    2015-05-01

    A case of malaria caused by Plasmodium knowlesi is described in a 52-year-old female German traveler after returning from Thailand. P. knowlesi is a parasite of macaques in Southeast Asia and has been recognized in recent years as an important and probably increasing cause of human malaria in some areas. At least 16 cases in international travelers have been published so far. This includes four cases imported to Germany. All German patients visited forested areas in Southern Thailand inhabited by the natural monkey host prior to their illness. Most cases diagnosed in endemic areas present as mild disease. However in some patients P. knowlesi may take a severe and life-threatening course. Diagnosis is usually is based on microscopy whereas rapid tests are not reliable. However, microscopic differentiation of P. knowlesi from other plasmodium species (eg, P. malariae, P. falciparum) is difficult, especially when parasitemia is low. Thus PCR methods are required for definite species determination. Changing endemicity as well as changing tourism patterns such as the trend towards eco-tourism might increase the risk of infection for travelers even in areas which are considered as low endemic for malaria. Malaria has to be considered in all febrile patients returning from endemic areas. In Southeast Asia this has to include Plasmodium knowlesi infection. Especially if microscopy suggests P. falciparum/P. malariae double infection, or when results indicate P. malariae but the clinical presentation differs from that of quartan malaria (eg, daily fever), diagnostic procedures for P. knowlesi should be initiated. Currently available rapid diagnostic tests are not reliable for the detection of P. knowlesi. The definite diagnosis of P. knowlesi infection usually requires PCR techniques Changing tourism patterns such as the trend towards eco-tourism might increase the risk of infection for travelers even in low prevalence areas. PMID:26080720

  6. Virulence and transmission success of the malarial parasite Plasmodium falciparum

    PubMed Central

    Hayward, Rhian E.; Tiwari, Bela; Piper, Karen P.; Baruch, Dror I.; Day, Karen P.

    1999-01-01

    Virulence of Plasmodium falciparum is associated with the expression of variant surface antigens designated PfEMP1 (P. falciparum erythrocyte membrane protein 1) that are encoded by a family of var genes. Data presented show that the transmission stages of P. falciparum also express PfEMP1 variants. Virulence in this host–parasite system can be considered a variable outcome of optimizing the production of sexual transmission stages from the population of disease-inducing asexual stages. Immunity to PfEMP1 will contribute to the regulation of this trade-off by controlling the parasite population with potential to produce mature transmission stages. PMID:10200302

  7. Three species of Plasmodium from Canada geese, Branta canadensis

    USGS Publications Warehouse

    Herman, C.M.; Barrow, J.H.

    1967-01-01

    Studies on Canada geese at the Seney National Wildlife Refuge in northern Michigan during the past few years have uncovered at least three species of Plasmodium: P circumflexum, P. relictum, and P. vaughani. Although rarely observed in direct blood smears from the wild hosts, isodiagnosis, using primarily domestic geese as recipients, revealed a prevalence of 60 percent in random samplings of the population. P. circumflexum is the most prevalent and mixed infections have been noted. In experimental infections, induced by blood inoculation, the malaria produced by P. circumflexum produces about a 70 percent mortality in Canada geese and about a 10 percent mortality in domestic geese.

  8. Intraerythrocytic stages of Plasmodium falciparum biosynthesize vitamin E.

    PubMed

    Sussmann, Rodrigo A C; Angeli, Cláudia B; Peres, Valnice J; Kimura, Emilia A; Katzin, Alejandro M

    2011-12-15

    The 2-C-methyl-D-erythritol-4-phosphate and shikimate pathways were found to be active in Plasmodium falciparum and both can result in vitamin E biosynthesis in plants and algae. This study biochemically confirmed vitamin E biosynthesis in the malaria parasite, which can be inhibited by usnic acid. Furthermore, we found evidence pointing to a role of this vitamin in infected erythrocytes. These findings not only contribute to current understanding of P. falciparum biology but also reveal a pathway that could serve as a chemotherapeutic target.

  9. Major Histocompatibility Complex and Malaria: Focus on Plasmodium vivax Infection

    PubMed Central

    Lima-Junior, Josué da Costa; Pratt-Riccio, Lilian Rose

    2016-01-01

    The importance of host and parasite genetic factors in malaria resistance or susceptibility has been investigated since the middle of the last century. Nowadays, of all diseases that affect man, malaria still plays one of the highest levels of selective pressure on human genome. Susceptibility to malaria depends on exposure profile, epidemiological characteristics, and several components of the innate and adaptive immune system that influences the quality of the immune response generated during the Plasmodium lifecycle in the vertebrate host. But it is well known that the parasite’s enormous capacity of genetic variation in conjunction with the host genetics polymorphism is also associated with a wide spectrum of susceptibility degrees to complicated or severe forms of the disease. In this scenario, variations in genes of the major histocompatibility complex (MHC) associated with host resistance or susceptibility to malaria have been identified and used as markers in host–pathogen interaction studies, mainly those evaluating the impact on the immune response, acquisition of resistance, or increased susceptibility to infection or vulnerability to disease. However, due to the intense selective pressure, number of cases, and mortality rates, the majority of the reported associations reported concerned Plasmodium falciparum malaria. Studies on the MHC polymorphism and its association with Plasmodium vivax, which is the most widespread Plasmodium and the most prevalent species outside the African continent, are less frequent but equally important. Despite punctual contributions, there are accumulated evidences of human genetic control in P. vivax infection and disease. Herein, we review the current knowledge in the field of MHC and derived molecules (HLA Class I, Class II, TNF-α, LTA, BAT1, and CTL4) regarding P. vivax malaria. We discuss particularly the results of P. vivax studies on HLA class I and II polymorphisms in relation to host susceptibility, naturally

  10. An Autochthonous Case of Severe Plasmodium knowlesi Malaria in Thailand

    PubMed Central

    Nakaviroj, Surat; Kobasa, Teerayot; Teeranaipong, Phairote; Putaporntip, Chaturong; Jongwutiwes, Somchai

    2015-01-01

    A 58-year-old Thai man was infected with Plasmodium knowlesi in Chantaburi Province, eastern Thailand. In addition to pyrexia, the patient developed hypotension, renal failure, jaundice, and severe thrombocytopenia. The parasitemia at the time of admission was 16.67% or ∼503,400 parasites/μL. With artesunate treatment and supportive care, the patient recovered uneventfully. The occurrence of complicated knowlesi malaria in a low-endemic area underscores the risk of high morbidity from this simian malaria. PMID:25535314

  11. [Artemisinin resistance in Plasmodium falciparum: global status and basic research].

    PubMed

    Zhao, Shao-min; Wang, Man-yuan

    2014-10-01

    Artemisinin-resistant Plasmodium falciparum has been identified by WHO in the Greater Mekong subregion. While there is no report on artemisinin resistance in Africa and South America by now, related surveillance measures have been taken place. The genes related artemisinin-resistance has been identified and the molecular markers will be used for large-scale surveillance efforts to contain artemisinin resistance. The emergence and spread of artemisinin resistance worldwide is a present danger and needs more attention. This article reviews the progress of artemisininresistance malaria parasites and artemisinin-based combination therapies. PMID:25726605

  12. Phenotypic and genotypic characterisation of drug-resistant Plasmodium vivax.

    PubMed

    Price, Ric N; Auburn, Sarah; Marfurt, Jutta; Cheng, Qin

    2012-11-01

    In this review we present recent developments in the analysis of Plasmodium vivax clinical trials and ex vivo drug-susceptibility assays, as well approaches currently being used to identify molecular markers of drug resistance. Clinical trials incorporating the measurement of in vivo drug concentrations and parasite clearance times are needed to detect early signs of resistance. Analysis of P. vivax growth dynamics ex vivo have defined the criteria for acceptable assay thresholds for drug susceptibility testing, and their subsequent interpretation. Genotyping and next-generation sequencing studies in P. vivax field isolates are set to transform our understanding of the molecular mechanisms of drug resistance.

  13. The epidemiology of Plasmodium falciparum gametocytes: weapons of mass dispersion.

    PubMed

    Drakeley, Chris; Sutherland, Colin; Bousema, J Teun; Sauerwein, Robert W; Targett, Geoffrey A T

    2006-09-01

    Much of the epidemiology of Plasmodium falciparum in Sub-Saharan Africa focuses on the prevalence patterns of asexual parasites in people of different ages, whereas the gametocytes that propagate the disease are often neglected. One expected benefit of the widespread introduction of artemisinin-based combination therapy for malaria is a reduction in gametocyte carriage. However, the factors that affect the transmission of parasites from humans to mosquitoes show complex dynamics in relation to the intensity and seasonality of malaria transmission, and thus such benefits might not be automatic. Here, we review data on gametocyte carriage in the context of the development of naturally acquired immunity and population infectivity. PMID:16846756

  14. Plasmodium knowlesi Sporozoite Antigen: Expression by Infectious Recombinant Vaccinia Virus

    NASA Astrophysics Data System (ADS)

    Smith, Geoffrey L.; Godson, G. Nigel; Nussenzweig, Victor; Nussenzweig, Ruth S.; Barnwell, John; Moss, Bernard

    1984-04-01

    The gene coding for the circumsporozoite antigen of the malaria parasite Plasmodium knowlesi was inserted into the vaccinia virus genome under the control of a defined vaccinia virus promoter. Cells infected with the recombinant virus synthesized polypeptides of 53,000 to 56,000 daltons that reacted with monoclonal antibody against the repeating epitope of the malaria protein. Furthermore, rabbits vaccinated with the recombinant virus produced antibodies that bound specifically to sporozoites. These data provide evidence for expression of a cloned malaria gene in mammalian cells and illustrate the potential of vaccinia virus recombinants as live malaria vaccines.

  15. Heterogeneous distribution of Plasmodium falciparum drug resistance haplotypes in subsets of the host population

    PubMed Central

    Schoepflin, Sonja; Marfurt, Jutta; Goroti, Mary; Baisor, Moses; Mueller, Ivo; Felger, Ingrid

    2008-01-01

    Background The emergence of drug resistance is a major problem in malaria control. For mathematical modelling of the transmission and spread of drug resistance the determinant parameters need to be identified and measured. The underlying hypothesis is that mutations associated with drug resistance incur fitness costs to the parasite in absence of drug pressure. The distribution of drug resistance haplotypes in different subsets of the host population was investigated. In particular newly acquired haplotypes after radical cure were characterized and compared to haplotypes from persistent infections. Methods Mutations associated with antimalarial drug resistance were analysed in parasites from children, adults, and new infections occurring after treatment. Twenty-five known single nucleotide polymorphisms from four Plasmodium falciparum genes associated with drug resistance were genotyped by DNA chip technology. Results Haplotypes were found to differ between subsets of the host population. A seven-fold mutated haplotype was significantly reduced in adults compared to children and new infections, whereas parasites harbouring fewer mutations were more frequent in adults. Conclusion The reduced frequency of highly mutated parasites in chronic infections in adults is likely a result of fitness costs of drug resistance that increases with number of mutations and is responsible for reduced survival of mutant parasites. PMID:18460212

  16. Antimalarial Iron Chelator FBS0701 Blocks Transmission by Plasmodium falciparum Gametocyte Activation Inhibition

    PubMed Central

    Ferrer, Patricia; Vega-Rodriguez, Joel; Tripathi, Abhai K.; Jacobs-Lorena, Marcelo

    2014-01-01

    Reducing the transmission of the malarial parasite by Anopheles mosquitoes using drugs or vaccines remains a main focus in the efforts to control malaria. Iron chelators have been studied as potential antimalarial drugs due to their activities against different stages of the parasite. The iron chelator FBS0701 affects the development of Plasmodium falciparum early gametocytes and lowers blood-stage parasitemia. Here, we tested the effect of FBS0701 on stage V gametocyte infectivity for mosquitoes. The incubation of stage V gametocytes for up to 3 days with increasing concentrations of FBS0701 resulted in a significant dose-related reduction in mosquito infectivity, as measured by the numbers of oocysts per mosquito. The reduction in mosquito infectivity was due to the inhibition of male and female gametocyte activation. The preincubation of FBS0701 with ferric chloride restored gametocyte infectivity, showing that the inhibitory effect of FBS0701 was quenched by iron. Deferoxamine, another iron chelator, also reduced gametocyte infectivity but to a lesser extent. Finally, the simultaneous administration of drug and gametocytes to mosquitoes without previous incubation did not significantly reduce the numbers of oocysts. These results show the importance of gametocyte iron metabolism as a potential target for new transmission-blocking strategies. PMID:25512427

  17. African apes as reservoirs of Plasmodium falciparum and the origin and diversification of the Laverania subgenus.

    PubMed

    Duval, Linda; Fourment, Mathieu; Nerrienet, Eric; Rousset, Dominique; Sadeuh, Serge A; Goodman, Steven M; Andriaholinirina, Nicole V; Randrianarivelojosia, Milijaona; Paul, Richard E; Robert, Vincent; Ayala, Francisco J; Ariey, Frédéric

    2010-06-01

    We investigated two mitochondrial genes (cytb and cox1), one plastid gene (tufA), and one nuclear gene (ldh) in blood samples from 12 chimpanzees and two gorillas from Cameroon and one lemur from Madagascar. One gorilla sample is related to Plasmodium falciparum, thus confirming the recently reported presence i