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Sample records for reducing plasmodium falciparum-infected

  1. Tetany with Plasmodium falciparum infection.

    PubMed

    Singh, P S; Singh, Neha

    2012-07-01

    Plasmodium falciparum is a malarial infection with high morbidity and wide spectrum of atypical presentation. Here we report an unusual presentation of malaria as tetany with alteration in calcium,phosphate and magnesium metabolism Hypocalcaemia in malaria can cause prolonged Q-Tc interval which could be arisk factor for quinine cardiotoxicity and sudden death Hence monitoring of serum calcium in severe malarial infection and cautious use of quinine in such patients is very important in management

  2. BLOOD-STAGE DYNAMICS AND CLINICAL IMPLICATIONS OF MIXED PLASMODIUM VIVAX–PLASMODIUM FALCIPARUM INFECTIONS

    PubMed Central

    MASON, DANIEL P.; McKENZIE, F. ELLIS

    2008-01-01

    We present a mathematical model of the blood-stage dynamics of mixed Plasmodium vivax–Plasmodium falciparum malaria infections in humans. The model reproduces features of such infections found in nature and suggests several phenomena that may merit clinical attention, including the potential recrudescence of a long-standing, low-level P. falciparum infection following a P. vivax infection or relapse and the capacity of an existing P. vivax infection to reduce the peak parasitemia of a P. falciparum superinfection. We simulate the administration of anti-malarial drugs, and illustrate some potential complications in treating mixed-species malaria infections. Notably, our model indicates that when a mixed-species infection is misdiagnosed as a single-species P. vivax infection, treatment for P. vivax can lead to a surge in P. falciparum parasitemia. PMID:10497972

  3. Prevalence of Plasmodium falciparum Infection in Rainy Season, Artibonite Valley, Haiti, 2006

    PubMed Central

    Keating, Joseph; Bennett, Adam; Londono, Berlin; Johnson, Dawn; Lafontant, Christina; Krogstad, Donald J.

    2007-01-01

    We conducted a population-based survey to estimate the prevalence of Plasmodium falciparum infection among persons older than 1 month in the Artibonite Valley of Haiti during the high malaria transmission season in 2006. Results from PCR for 714 persons showed a prevalence of 3.1% for P. falciparum infection. PMID:18257993

  4. Prevalence of Plasmodium falciparum infection in rainy season, Artibonite Valley, Haiti, 2006.

    PubMed

    Eisele, Thomas P; Keating, Joseph; Bennett, Adam; Londono, Berlin; Johnson, Dawn; Lafontant, Christina; Krogstad, Donald J

    2007-10-01

    We conducted a population-based survey to estimate the prevalence of Plasmodium falciparum infection among persons older than 1 month in the Artibonite Valley of Haiti during the high malaria transmission season in 2006. Results from PCR for 714 persons showed a prevalence of 3.1% for P. falciparum infection.

  5. Volatile organic compounds associated with Plasmodium falciparum infection in vitro.

    PubMed

    Correa, Ricardo; Coronado, Lorena M; Garrido, Anette C; Durant-Archibold, Armando A; Spadafora, Carmenza

    2017-05-02

    In order to identify new ways to prevent transmission of vector-borne diseases such as malaria, efforts have been made to understand how insects are attracted to humans. Vector-host interaction studies have shown that several volatile compounds play an important role in attracting mosquitoes to human targets. A headspace solid-phase micro-extraction/gas chromatography-mass spectrometry (HSPME GC-MS) analysis of the volatile organic composition of extracellular vesicles (EVs) and supernatants of ultracentrifugation (SNUs) was carried out in Plasmodium falciparum-infected cultures with high and low parasitemias. A list of 18 volatile organic compounds (VOCs) was obtained from the EVs of both infected and uninfected RBCs with 1,2,3-Propanetriol, diacetate (diacetin) increased in the infected EVs, regardless of the parasitemia of the culture. The supernatant analysis, however, gave off 56 VOCs, with pentane 2,2,4-trimethyl being present in all the SNUs of uninfected erythrocytes but absent from the parasite-infected ones. Standing out in this study was hexanal, a reported insect attractant, which was the only VOC present in all samples from SNUs from infected erythrocytes and absent from uninfected ones, suggesting that it originates during parasite infection. The hexanal compound, reportedly a low-level component found in healthy human samples such as breath and plasma, had not been found in previous analyses of P. falciparum-infected patients or cultures. This compound has been reported as an Anopheles gambiae attractant in plants. While the compound could be produced during infection by the malaria parasite in human erythrocytes, the A. gambiae attraction could be used by the parasite as a strategy for transmission.

  6. Sickle Cell Trait Protects Against Plasmodium falciparum Infection

    PubMed Central

    Billo, Mounkaila A.; Johnson, Eric S.; Doumbia, Seydou O.; Poudiougou, Belco; Sagara, Issaka; Diawara, Sory I.; Diakité, Mahamadou; Diallo, Mouctar; Doumbo, Ogobara K.; Tounkara, Anatole; Rice, Janet; James, Mark A.; Krogstad, Donald J.

    2012-01-01

    Although sickle cell trait protects against severe disease due to Plasmodium falciparum, it has not been clear whether sickle trait also protects against asymptomatic infection (parasitemia). To address this question, the authors identified 171 persistently smear-negative children and 450 asymptomatic persistently smear-positive children in Bancoumana, Mali (June 1996 to June 1998). They then followed both groups for 2 years using a cohort-based strategy. Among the 171 children with persistently negative smears, the median time for conversion to smear-positive was longer for children with sickle trait than for children without (274 vs. 108 days, P < 0.001; Cox hazard ratio = 0.56, 95% confidence interval: 0.33, 0.96; P = 0.036). Similar differences were found in the median times to reinfection after spontaneous clearance without treatment (365 days vs. 184 days; P = 0.01). Alternatively, among the 450 asymptomatic children with persistently positive smears, the median time for conversion to smear-negative (spontaneous clearance) was shorter for children with sickle trait than for children without (190 vs. 365 days; P = 0.02). These protective effects of sickle trait against asymptomatic P. falciparum infection under conditions of natural transmission were demonstrable using a cohort-based approach but not when the same data were examined using a cross-sectional approach. PMID:23035141

  7. Asymptomatic Multiclonal Plasmodium falciparum Infections Carried Through the Dry Season Predict Protection Against Subsequent Clinical Malaria

    PubMed Central

    Sondén, Klara; Doumbo, Safiatou; Hammar, Ulf; Vafa Homann, Manijeh; Ongoiba, Aissata; Traoré, Boubacar; Bottai, Matteo; Crompton, Peter D.; Färnert, Anna

    2015-01-01

    Background Immunity to the antigenically diverse parasite Plasmodium falciparum is acquired gradually after repeated exposure. Studies in areas of high malaria transmission have shown that asymptomatic individuals infected with multiclonal infections are at reduced risk of febrile malaria during follow-up. Methods We assessed the relationship between the genetic diversity of clones in P. falciparum infections that persist through the dry season and the subsequent risk of febrile malaria in 225 individuals aged 2–25 years in Mali, where the 6-month malaria and dry seasons are sharply demarcated. Polymerase chain reaction–based genotyping of the highly polymorphic merozoite surface protein 2 gene was performed on blood samples collected at 5 cross-sectional surveys. Results In an age-adjusted analysis, individuals with multiclonal P. falciparum infections before the rainy season were at reduced risk of febrile malaria, compared with individuals who were uninfected (hazard ratio [HR], 0.28; 95% confidence interval [CI], .11–.69). In contrast, there was no significant association between risk of malaria and having 1 clone at baseline (HR, 0.71; 95% CI, .36–1.40). Conclusions The results suggest that persistent multiclonal infections carried through the dry season contribute to protection against subsequent febrile malaria, possibly by maintaining protective immune responses that depend on ongoing parasite infection. PMID:25712968

  8. Loss of Humoral and Cellular Immunity to Invasive Nontyphoidal Salmonella during Current or Convalescent Plasmodium falciparum Infection in Malawian Children.

    PubMed

    Nyirenda, Tonney S; Nyirenda, James T; Tembo, Dumizulu L; Storm, Janet; Dube, Queen; Msefula, Chisomo L; Jambo, Kondwani C; Mwandumba, Henry C; Heyderman, Robert S; Gordon, Melita A; Mandala, Wilson L

    2017-07-01

    Invasive nontyphoidal Salmonella (iNTS) infections are commonly associated with Plasmodium falciparum infections, but the immunologic basis for this linkage is poorly understood. We hypothesized that P. falciparum infection compromises the humoral and cellular immunity of the host to NTS, which increases the susceptibility of the host to iNTS infection. We prospectively recruited children aged between 6 and 60 months at a Community Health Centre in Blantyre, Malawi, and allocated them to the following groups; febrile with uncomplicated malaria, febrile malaria negative, and nonfebrile malaria negative. Levels of Salmonella enterica serovar Typhimurium-specific serum bactericidal activity (SBA) and whole-blood bactericidal activity (WBBA), complement C3 deposition, and neutrophil respiratory burst activity (NRBA) were measured. Levels of SBA with respect to S Typhimurium were reduced in febrile P. falciparum-infected children (median, -0.20 log10 [interquartile range {IQR}, -1.85, 0.32]) compared to nonfebrile malaria-negative children (median, -1.42 log10 [IQR, -2.0, -0.47], P = 0.052). In relation to SBA, C3 deposition on S Typhimurium was significantly reduced in febrile P. falciparum-infected children (median, 7.5% [IQR, 4.1, 15.0]) compared to nonfebrile malaria-negative children (median, 29% [IQR, 11.8, 48.0], P = 0.048). WBBA with respect to S Typhimurium was significantly reduced in febrile P. falciparum-infected children (median, 0.25 log10 [IQR, -0.73, 1.13], P = 0.0001) compared to nonfebrile malaria-negative children (median, -1.0 log10 [IQR, -1.68, -0.16]). In relation to WBBA, S Typhimurium-specific NRBA was reduced in febrile P. falciparum-infected children (median, 8.8% [IQR, 3.7, 20], P = 0.0001) compared to nonfebrile malaria-negative children (median, 40.5% [IQR, 33, 65.8]). P. falciparum infection impairs humoral and cellular immunity to S Typhimurium in children during malaria episodes, which may explain the increased risk of iNTS observed in

  9. ABO Blood Groups Influence Macrophage-mediated Phagocytosis of Plasmodium falciparum-infected Erythrocytes

    PubMed Central

    Branch, Donald R.; Hult, Annika K.; Olsson, Martin L.; Liles, W. Conrad; Cserti-Gazdewich, Christine M.; Kain, Kevin C.

    2012-01-01

    Erythrocyte polymorphisms associated with a survival advantage to Plasmodium falciparum infection have undergone positive selection. There is a predominance of blood group O in malaria-endemic regions, and several lines of evidence suggest that ABO blood groups may influence the outcome of P. falciparum infection. Based on the hypothesis that enhanced innate clearance of infected polymorphic erythrocytes is associated with protection from severe malaria, we investigated whether P. falciparum-infected O erythrocytes are more efficiently cleared by macrophages than infected A and B erythrocytes. We show that human macrophages in vitro and mouse monocytes in vivo phagocytose P. falciparum-infected O erythrocytes more avidly than infected A and B erythrocytes and that uptake is associated with increased hemichrome deposition and high molecular weight band 3 aggregates in infected O erythrocytes. Using infected A1, A2, and O erythrocytes, we demonstrate an inverse association of phagocytic capacity with the amount of A antigen on the surface of infected erythrocytes. Finally, we report that enzymatic conversion of B erythrocytes to type as O before infection significantly enhances their uptake by macrophages to observed level comparable to that with infected O wild-type erythrocytes. These data provide the first evidence that ABO blood group antigens influence macrophage clearance of P. falciparum-infected erythrocytes and suggest an additional mechanism by which blood group O may confer resistance to severe malaria. PMID:23071435

  10. Housing conditions and Plasmodium falciparum infection: protective effect of iron-sheet roofed houses.

    PubMed

    Yé, Yazoumé; Hoshen, Moshe; Louis, Valérie; Séraphin, Simboro; Traoré, Issouf; Sauerborn, Rainer

    2006-02-01

    Identification and better understanding of potential risk factors for malaria are important for targeted and cost-effective health interventions. Housing conditions have been suggested as one of the potential risk factors. This study aims to further investigate this risk factor, and is focused on the effect of the type of roof on Plasmodium falciparum infection among children below five years in the North West of Burkina Faso. In a cross-sectional study design, 661 children aged six to 60 months were randomly selected from three rural and one semi-urban site at the end of the rainy season (November 2003). The children were screened for fever and tested for Plasmodium falciparum infection. In addition, data on bed net use and house characteristics was collected from the household were each child lived. Using adjusted odds ratios, children living in house roofed with iron-sheet were compared with those in house with mud or grass roof. Overall P. falciparum infection prevalence was 22.8 % with a significant variation between (Chi-square, p < 0.0001). The prevalence in Cissé (33.3 %) and Goni (30.6 %) were twice times more than in Nouna (15.2 %) and Kodougou (13.2 %). After adjusting for age, sex, use of bed net and housing conditions, children living in houses with mud roofs had significantly higher risk of getting P. falciparum infection compared to those living in iron-sheet roofed houses (Odds Ratio 2.6; 95% Confidence Interval, 1.4-4.7). These results suggest that house characteristics should be taken into consideration when designing health intervention against P. falciparum infection and particular attention should be paid to children living in houses with mud roofs.

  11. Biomarkers of Plasmodium falciparum Infection during Pregnancy in Women Living in Northeastern Tanzania

    PubMed Central

    Boström, Stéphanie; Ibitokou, Samad; Oesterholt, Mayke; Schmiegelow, Christentze; Persson, Jan-Olov; Minja, Daniel; Lusingu, John; Lemnge, Martha; Fievet, Nadine; Deloron, Philippe; Luty, Adrian J. F.; Troye-Blomberg, Marita

    2012-01-01

    In pregnant women, Plasmodium falciparum infections are an important cause of maternal morbidity as well as fetal and neonatal mortality. Erythrocytes infected by these malaria-causing parasites accumulate through adhesive interactions in placental intervillous spaces, thus evading detection in peripheral blood smears. Sequestered infected erythrocytes induce inflammation, offering the possibility of detecting inflammatory mediators in peripheral blood that could act as biomarkers of placental infection. In a longitudinal, prospective study in Tanzania, we quantified a range of different cytokines, chemokines and angiogenic factors in peripheral plasma samples, taken on multiple sequential occasions during pregnancy up to and including delivery, from P. falciparum-infected women and matched uninfected controls. The results show that during healthy, uninfected pregnancies the levels of most of the panel of molecules we measured were largely unchanged except at delivery. In women with P. falciparum, however, both comparative and longitudinal assessments consistently showed that the levels of IL-10 and IP-10 increased significantly whilst that of RANTES decreased significantly, regardless of gestational age at the time the infection was detected. ROC curve analysis indicated that a combination of increased IL-10 and IP-10 levels and decreased RANTES levels might be predictive of P. falciparum infections. In conclusion, our data suggest that host biomarkers in peripheral blood may represent useful diagnostic markers of P. falciparum infection during pregnancy, but placental histology results would need to be included to verify these findings. PMID:23155405

  12. Spatial variation of Anopheles-transmitted Wuchereria bancrofti and Plasmodium falciparum infection densities in Papua New Guinea

    PubMed Central

    Alexander, Neal D; Moyeed, Rana A; Hyun, Phil J; Dimber, Zachary B; Bockarie, Moses J; Stander, Julian; Grenfell, Bryan T; Kazura, James W; Alpers, Michael P

    2003-01-01

    The spatial variation of Wuchereria bancrofti and Plasmodium falciparum infection densities was measured in a rural area of Papua New Guinea where they share anopheline vectors. The spatial correlation of W. bancrofti was found to reduce by half over an estimated distance of 1.7 km, much smaller than the 50 km grid used by the World Health Organization rapid mapping method. For P. falciparum, negligible spatial correlation was found. After mass treatment with anti-filarial drugs, there was negligible correlation between the changes in the densities of the two parasites. PMID:14525619

  13. Plasmodium falciparum infection and clinical indicators in relation to net coverage in central Côte d’Ivoire

    PubMed Central

    2014-01-01

    Background Sleeping under a net, particularly a long-lasting insecticidal net (LLIN), is associated with reduced malaria morbidity and mortality, but requires high coverage and adherence. In this study, parasitologically confirmed Plasmodium falciparum infection and a clinical indicator (i.e. fever) were measured among children in three villages of central Côte d’Ivoire (Bozi, N’Dakonankro and Yoho) and associations with net coverage explored. In Bozi and Yoho, LLINs were provided by the national malaria control programme, prior to the study and an additional catch-up coverage was carried out in Bozi. In N’Dakonankro, no net intervention was conducted. Methods Three cross-sectional surveys were carried out; two in the dry season (February 2010 and November 2011) and one in the rainy season (May 2012). Among 897 children aged <15 years, P. falciparum infection was determined by microscopy and a rapid diagnostic test (RDT). Fever was defined as an axillary temperature ≥37.5°C. A questionnaire was administered to obtain demographic data and net usage. Results The proportion of children infected with P. falciparum according to microscopy in the third survey was 74%, 81% and 82% in Yoho, N’Dakonankro and Bozi, respectively. Meanwhile, 46% of the children in N’Dakonankro, 44% in Bozi and 33% in Yoho slept under a net. The risk of P. falciparum infection did not differ between net-sleepers and non-net-sleepers. Fewer children had parasitaemia ≥1,000 parasites/μl of blood in Bozi in the third compared to the first survey. Fever was poorly correlated with P. falciparum infection. The risk of P. falciparum infection did not depend on the village of residence, presence of fever or sleeping under LLIN the night before the survey. Conversely, it was higher in the rainy season and among older children. Conclusions In an area where P. falciparum is highly prevalent, the use of nets was associated with significantly lower levels of parasitaemia. The

  14. The Dynamics of Naturally Acquired Immunity to Plasmodium falciparum Infection

    PubMed Central

    Pinkevych, Mykola; Petravic, Janka; Chelimo, Kiprotich; Kazura, James W.; Moormann, Ann M.; Davenport, Miles P.

    2012-01-01

    Severe malaria occurs predominantly in young children and immunity to clinical disease is associated with cumulative exposure in holoendemic settings. The relative contribution of immunity against various stages of the parasite life cycle that results in controlling infection and limiting disease is not well understood. Here we analyse the dynamics of Plasmodium falciparum malaria infection after treatment in a cohort of 197 healthy study participants of different ages in order to model naturally acquired immunity. We find that both delayed time-to-infection and reductions in asymptomatic parasitaemias in older age groups can be explained by immunity that reduces the growth of blood stage as opposed to liver stage parasites. We found that this mechanism would require at least two components – a rapidly acting strain-specific component, as well as a slowly acquired cross-reactive or general immunity to all strains. Analysis and modelling of malaria infection dynamics and naturally acquired immunity with age provides important insights into what mechanisms of immune control may be harnessed by malaria vaccine strategists. PMID:23093922

  15. 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

  16. Quantitative pH measurements in Plasmodium falciparum-infected erythrocytes using pHluorin.

    PubMed

    Kuhn, Yvonne; Rohrbach, Petra; Lanzer, Michael

    2007-04-01

    The digestive vacuole of the malaria parasite Plasmodium falciparum is the site of action of several antimalarial drugs, such as chloroquine, which accumulate in this organelle due to their properties as amphiphilic weak bases that inhibit haem detoxification. It has been suggested that changes in the pH of the digestive vacuole, affecting either drug partitioning or haem solubility and/or biomineralization rates, would correlate with reduced intracellular chloroquine accumulation and, hence, would determine the chloroquine-resistance phenotype. The techniques previously used to quantify digestive vacuolar pH mainly relied on lysed or isolated parasites, with unpredictable consequences on internal pH homeostasis. In this study, we have investigated the baseline steady-state pH of the cytoplasm and digestive vacuole of a chloroquine-sensitive (HB3) and a chloroquine-resistant (Dd2) parasite using a pH-sensitive green fluorescent protein, termed pHluorin. This non-invasive technique allows for in vivo pH measurements in intact P. falciparum-infected erythrocytes under physiological conditions. The data suggest that the pH of the cytoplasm is approximately 7.15 +/- 0.07 and that of the digestive vacuole approximately 5.18 +/- 0.05. No significant differences in baseline pH values were recorded for the chloroquine-sensitive and chloroquine-resistant parasites.

  17. Multiple genotypes of the merozoite surface proteins 1 and 2 in Plasmodium falciparum infections in a hypoendemic area in Iran.

    PubMed

    Zakeri, Sedigheh; Bereczky, Sándor; Naimi, Parin; Pedro Gil, J; Djadid, Navid Dinparast; Färnert, Anna; Snounou, Georges; Björkman, Anders

    2005-10-01

    In Iran, malaria transmission mainly occurs in south-eastern regions through both Plasmodium falciparum and P. vivax. The genetic diversity of P. falciparum isolates was analysed in 108 patients attending the regional hospital in Chabahar District, using the molecular markers msp1 and msp2. Multiple genotypes were detected in 87% of patients and the mean numbers of msp1 and msp2 genotypes were 2.51 (95% CI: 2.29-2.73) and 2.61 (95% CI: 2.39-2.83) respectively. Various allelic types of msp1 and msp2 were found, with msp2 3D7/IC type detected in 94% of infections. Plasmodium falciparum infections in south-east Iran appear to have a higher genetic diversity than expected for an area of low transmission. A situation of higher transmission in this area may be emerging, possibly because of reduced efficacy of first-line treatments.

  18. Plasmodium falciparum-infected mice: more than a tour de force.

    PubMed

    Moreno, Alicia; Pérignon, Jean Louis; Morosan, Serban; Mazier, Dominique; Benito, Agustin

    2007-06-01

    Up until recently, the relevance of Plasmodium falciparum-infected humanized mice for malaria studies has been questioned because of the low percentage of mice in which the parasite develops. Advances in the generation of new immunodeficient mouse strains combined with the use of protocols that modulate the innate immune defenses of mice have facilitated the harvesting of exoerythrocytic and intraerythrocytic stages of the parasite. These results renew the hope of working with P. falciparum in a laboratory animal and indicate that the next challenge (i.e. a complete parasite cycle in the same mouse, including transmission to mosquito) could be reached in the future.

  19. 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.

  20. Cryo scanning electron microscopy of Plasmodium falciparum-infected erythrocytes.

    PubMed

    Hempel, Casper

    2017-07-01

    Plasmodium falciparum invades erythrocytes as an essential part of their life cycle. While living inside erythrocytes, the parasite remodels the cell's intracellular organization as well as its outer surface. Late trophozoite-stage parasites and schizonts introduce numerous small protrusions on the erythrocyte surface, called knobs. Current methods for studying these knobs include atomic force microscopy and electron microscopy. Standard electron microscopy methods rely on chemical fixation and dehydration modifying cell size. Here, a novel method is presented using rapid freezing and scanning electron microscopy under cryogenic conditions allowing for high resolution and magnification of erythrocytes. This novel technique can be used for precise estimates of knob density and for studies on cytoadhesion. © 2017 APMIS. Published by John Wiley & Sons Ltd.

  1. 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

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

    PubMed

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

    2015-10-01

    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.

  3. Prevalence of Plasmodium falciparum infection in pregnant women in Gabon

    PubMed Central

    Bouyou-Akotet, Marielle K; Ionete-Collard, Denisa E; Mabika-Manfoumbi, Modeste; Kendjo, Eric; Matsiegui, Pierre-Blaise; Mavoungou, Elie; Kombila, Maryvonne

    2003-01-01

    Background In areas where malaria is endemic, pregnancy is associated with increased susceptibility to malaria. It is generally agreed that this risk ends with delivery and decreases with the number of pregnancies. Our study aimed to demonstrate relationships between malarial parasitaemia and age, gravidity and anaemia in pregnant women in Libreville, the capital city of Gabon. Methods Peripheral blood was collected from 311 primigravidae and women in their second pregnancy. Thick blood smears were checked, as were the results of haemoglobin electrophoresis. We also looked for the presence of anaemia, fever, and checked whether the volunteers had had chemoprophylaxis. The study was performed in Gabon where malaria transmission is intense and perennial. Results A total of 177 women (57%) had microscopic parasitaemia; 139 (64%)of them were primigravidae, 38 (40%) in their second pregnancy and 180 (64%) were teenagers. The parasites densities were also higher in primigravidae and teenagers. The prevalence of anaemia was 71% and was associated with microscopic Plasmodium falciparum parasitaemia: women with moderate or severe anaemia had higher parasite prevalences and densities. However, the sickle cell trait, fever and the use of chemoprophylaxis did not have a significant association with the presence of P. falciparum. Conclusions These results suggest that the prevalence of malaria and the prevalence of anaemia, whether associated with malaria or not, are higher in pregnant women in Gabon. Primigravidae and young pregnant women are the most susceptible to infection. It is, therefore, urgent to design an effective regimen of malaria prophylaxis for this high risk population. PMID:12919637

  4. FRET imaging of hemoglobin concentration in Plasmodium falciparum-infected red cells.

    PubMed

    Esposito, Alessandro; Tiffert, Teresa; Mauritz, Jakob M A; Schlachter, Simon; Bannister, Lawrence H; Kaminski, Clemens F; Lew, Virgilio L

    2008-01-01

    During its intraerythrocytic asexual reproduction cycle Plasmodium falciparum consumes up to 80% of the host cell hemoglobin, in large excess over its metabolic needs. A model of the homeostasis of falciparum-infected red blood cells suggested an explanation based on the need to reduce the colloid-osmotic pressure within the host cell to prevent its premature lysis. Critical for this hypothesis was that the hemoglobin concentration within the host cell be progressively reduced from the trophozoite stage onwards. The experiments reported here were designed to test this hypothesis by direct measurements of the hemoglobin concentration in live, infected red cells. We developed a novel, non-invasive method to quantify the hemoglobin concentration in single cells, based on Förster resonance energy transfer between hemoglobin molecules and the fluorophore calcein. Fluorescence lifetime imaging allowed the quantitative mapping of the hemoglobin concentration within the cells. The average fluorescence lifetimes of uninfected cohorts was 270+/-30 ps (mean+/-SD; N = 45). In the cytoplasm of infected cells the fluorescence lifetime of calcein ranged from 290+/-20 ps for cells with ring stage parasites to 590+/-13 ps and 1050+/-60 ps for cells with young trophozoites and late stage trophozoite/early schizonts, respectively. This was equivalent to reductions in hemoglobin concentration spanning the range from 7.3 to 2.3 mM, in line with the model predictions. An unexpected ancillary finding was the existence of a microdomain under the host cell membrane with reduced calcein quenching by hemoglobin in cells with mature trophozoite stage parasites. The results support the predictions of the colloid-osmotic hypothesis and provide a better understanding of the homeostasis of malaria-infected red cells. In addition, they revealed the existence of a distinct peripheral microdomain in the host cell with limited access to hemoglobin molecules indicating the concentration of

  5. Diagnosis of Plasmodium falciparum infection in man: detection of parasite antigens by ELISA*

    PubMed Central

    Mackey, L. J.; McGregor, I. A.; Paounova, N.; Lambert, P. H.

    1982-01-01

    An ELISA method has been developed for the diagnosis of Plasmodium falciparum infection in man. Parasites from in vitro cultures of P. falciparum were used as source of antigen for the solid phase and the source of specific antibody was immune Gambian sera; binding of antibody in antigen-coated wells was registered by means of alkaline phosphatase-conjugated anti-human IgG. Parasites were detected on the basis of inhibition of antibody-binding. The test was applied to the detection of parasites in human red blood cells (RBC) from in vitro cultures of P. falciparum and in RBC from infected Gambians; RBC from 100 Geneva blood donors served as normal, uninfected controls. In titration experiments, the degree of antibody-binding inhibition correlated with the number of parasites in the test RBC. Parasites were detected at a level of 8 parasites/106 RBC. Samples of RBC were tested from 126 Gambians with microscopically proven infection; significant antibody-binding inhibition was found in 86% of these cases, where parasitaemia ranged from 10 to 125 000/μl of blood. The presence of high-titre antibody in the test preparations was found to reduce the sensitivity of parasite detection in infected RBC from in vitro cultures mixed with equal volumes of different antibody-containing sera. The sensitivity was restored in most cases by recovering the RBC by centrifugation before testing. In a preliminary experiment, there was no significant difference in antibody-binding inhibition using fresh infected RBC and RBC dried on filter-paper and recovered by elution, although there was greater variation in the latter samples. PMID:7044589

  6. Diagnosis of Plasmodium falciparum infection in man: detection of parasite antigens by ELISA.

    PubMed

    Mackey, L J; McGregor, I A; Paounova, N; Lambert, P H

    1982-01-01

    An ELISA method has been developed for the diagnosis of Plasmodium falciparum infection in man. Parasites from in vitro cultures of P. falciparum were used as source of antigen for the solid phase and the source of specific antibody was immune Gambian sera; binding of antibody in antigen-coated wells was registered by means of alkaline phosphatase-conjugated anti-human IgG. Parasites were detected on the basis of inhibition of antibody-binding. The test was applied to the detection of parasites in human red blood cells (RBC) from in vitro cultures of P. falciparum and in RBC from infected Gambians; RBC from 100 Geneva blood donors served as normal, uninfected controls. In titration experiments, the degree of antibody-binding inhibition correlated with the number of parasites in the test RBC. Parasites were detected at a level of 8 parasites/10(6) RBC. Samples of RBC were tested from 126 Gambians with microscopically proven infection; significant antibody-binding inhibition was found in 86% of these cases, where parasitaemia ranged from 10 to 125 000/mul of blood. The presence of high-titre antibody in the test preparations was found to reduce the sensitivity of parasite detection in infected RBC from in vitro cultures mixed with equal volumes of different antibody-containing sera. The sensitivity was restored in most cases by recovering the RBC by centrifugation before testing. In a preliminary experiment, there was no significant difference in antibody-binding inhibition using fresh infected RBC and RBC dried on filter-paper and recovered by elution, although there was greater variation in the latter samples.

  7. Plasmodium falciparum Infection Does Not Affect Human Immunodeficiency Virus Viral Load in Coinfected Rwandan Adults

    PubMed Central

    Subramaniam, Krishanthi; Plank, Rebeca M.; Lin, Nina; Goldman-Yassen, Adam; Ivan, Emil; Becerril, Carlos; Kemal, Kimdar; Heo, Moonseong; Keller, Marla J.; Mutimura, Eugene; Anastos, Kathryn; Daily, Johanna P.

    2014-01-01

    Background  Plasmodium falciparum infection has been reported to increase human immunodeficiency virus (HIV) viral load (VL), which can facilitate HIV transmission. We prospectively studied the impact of mild P falciparum coinfection on HIV VL in Rwanda. Methods  We measured plasma HIV VL at presentation with malaria infection and weekly for 4 weeks after artemether-lumefantrine treatment in Rwandan adults infected with HIV with P falciparum malaria. Regression analyses were used to examine associations between malaria infection and HIV VL changes. Samples with detectable virus underwent genotypic drug-resistance testing. Results  We enrolled 28 HIV-malaria coinfected patients and observed 27 of them for 5 weeks. Three patients (11%) were newly diagnosed with HIV. Acute P falciparum infection had no significant effect on HIV VL slope over 28 days of follow-up. Ten patients with VL <40 copies/mL at enrollment maintained viral suppression throughout. Seventeen patients had a detectable VL at enrollment including 9 (53%) who reported 100% adherence to ARVs; 3 of these had detectable genotypic drug resistance. Conclusions  Unlike studies from highly malaria-endemic areas, we did not identify an effect of P falciparum infection on HIV VL; therefore, malaria is not likely to increase HIV-transmission risk in our setting. However, routine HIV testing should be offered to adults presenting with acute malaria in Rwanda. Most importantly, we identified a large percentage of patients with detectable HIV VL despite antiretroviral (ARV) therapy. Some of these patients had HIV genotypic drug resistance. Larger studies are needed to define the prevalence and factors associated with detectable HIV VL in patients prescribed ARVs in Rwanda. PMID:25734136

  8. Plasmodium falciparum Infection Does Not Affect Human Immunodeficiency Virus Viral Load in Coinfected Rwandan Adults.

    PubMed

    Subramaniam, Krishanthi; Plank, Rebeca M; Lin, Nina; Goldman-Yassen, Adam; Ivan, Emil; Becerril, Carlos; Kemal, Kimdar; Heo, Moonseong; Keller, Marla J; Mutimura, Eugene; Anastos, Kathryn; Daily, Johanna P

    2014-09-01

    Plasmodium falciparum infection has been reported to increase human immunodeficiency virus (HIV) viral load (VL), which can facilitate HIV transmission. We prospectively studied the impact of mild P falciparum coinfection on HIV VL in Rwanda. We measured plasma HIV VL at presentation with malaria infection and weekly for 4 weeks after artemether-lumefantrine treatment in Rwandan adults infected with HIV with P falciparum malaria. Regression analyses were used to examine associations between malaria infection and HIV VL changes. Samples with detectable virus underwent genotypic drug-resistance testing. We enrolled 28 HIV-malaria coinfected patients and observed 27 of them for 5 weeks. Three patients (11%) were newly diagnosed with HIV. Acute P falciparum infection had no significant effect on HIV VL slope over 28 days of follow-up. Ten patients with VL <40 copies/mL at enrollment maintained viral suppression throughout. Seventeen patients had a detectable VL at enrollment including 9 (53%) who reported 100% adherence to ARVs; 3 of these had detectable genotypic drug resistance. Unlike studies from highly malaria-endemic areas, we did not identify an effect of P falciparum infection on HIV VL; therefore, malaria is not likely to increase HIV-transmission risk in our setting. However, routine HIV testing should be offered to adults presenting with acute malaria in Rwanda. Most importantly, we identified a large percentage of patients with detectable HIV VL despite antiretroviral (ARV) therapy. Some of these patients had HIV genotypic drug resistance. Larger studies are needed to define the prevalence and factors associated with detectable HIV VL in patients prescribed ARVs in Rwanda.

  9. Modulation of Whole-Cell Currents in Plasmodium Falciparum-Infected Human Red Blood Cells by Holding Potential and Serum

    PubMed Central

    Staines, Henry M; Powell, Trevor; Clive Ellory, J; Egée, Stéphane; Lapaix, Franck; Decherf, Gaëtan; Thomas, Serge L Y; Duranton, Christophe; Lang, Florian; Huber, Stephan M

    2003-01-01

    Recent electrophysiological studies have identified novel ion channel activity in the host plasma membrane of Plasmodium falciparum-infected human red blood cells (RBCs). However, conflicting data have been published with regard to the characteristics of induced channel activity measured in the whole-cell configuration of the patch-clamp technique. In an effort to establish the reasons for these discrepancies, we demonstrate here two factors that have been found to modulate whole-cell recordings in malaria-infected RBCs. Firstly, negative holding potentials reduced inward currents (i.e. at negative potentials), although this result was highly complex. Secondly, the addition of human serum increased outward currents (i.e. at positive potentials) by approximately 4-fold and inward currents by approximately 2-fold. These two effects may help to resolve the conflicting data in the literature, although further investigation is required to understand the underlying mechanisms and their physiological relevance in detail. PMID:12937282

  10. Usefulness of the recombinant liver stage antigen-3 for an early serodiagnosis of Plasmodium falciparum infection

    PubMed Central

    Lee, Hyeong-Woo; Moon, Sung-Ung; Ryu, Hye-Sun; Kim, Yeon-Joo; Cho, Shin-Hyeong; Chung, Gyung-Tae; Lin, Khin; Na, Byoung-Kuk; Kong, Yoon; Chung, Kyung-Suk

    2006-01-01

    In order to develop tools for an early serodiagnosis of Plasmodium falciparum infection, we evaluated the usefulness of P. falciparum liver stage antigen-3 (LSA-3) as a serodiagnostic antigen. A portion of LSA-3 gene was cloned, and its recombinant protein (rLSA-3) was expressed in Escherichia coli and purified by column chromatography. The purified rLSA-3 and 120 test blood/serum samples collected from inhabitants in malaria-endemic areas of Mandalay, Myanmar were used for this study. In microscopic examinations of blood samples, P. falciparum positive rate was 39.1% (47/120) in thin smear trials, and 33.3% (40/120) in thick smear trials. Although the positive rate associated with the rLSA-3 (30.8%) was lower than that of the blood stage antigens (70.8%), rLSA-3 based enzyme-linked immunosorbent assay could detect 12 seropositive cases (10.0%), in which blood stage antigens were not detected. These results indicate that the LSA-3 is a useful antigen for an early serodiagnosis of P. falciparum infection. PMID:16514282

  11. Usefulness of the recombinant liver stage antigen-3 for an early serodiagnosis of Plasmodium falciparum infection.

    PubMed

    Lee, Hyeong-Woo; Moon, Sung-Ung; Ryu, Hye-Sun; Kim, Yeon-Joo; Cho, Shin-Hyeong; Chung, Gyung-Tae; Lin, Khin; Na, Byoung-Kuk; Kong, Yoon; Chung, Kyung-Suk; Kim, Tong-Soo

    2006-03-01

    In order to develop tools for an early serodiagnosis of Plasmodium falciparum infection, we evaluated the usefulness of P. falciparum liver stage antigen-3 (LSA-3) as a serodiagnostic antigen. A portion of LSA-3 gene was cloned, and its recombinant protein (rLSA-3) was expressed in Escherichia coli and purified by column chromatography. The purified rLSA-3 and 120 test blood/serum samples collected from inhabitants in malaria-endemic areas of Mandalay, Myanmar were used for this study. In microscopic examinations of blood samples, P. falciparum positive rate was 39.1% (47/120) in thin smear trials, and 33.3% (40/120) in thick smear trials. Although the positive rate associated with the rLSA-3 (30.8%) was lower than that of the blood stage antigens (70.8%), rLSA-3 based enzyme-linked immunosorbent assay could detect 12 seropositive cases (10.0%), in which blood stage antigens were not detected. These results indicate that the LSA-3 is a useful antigen for an early serodiagnosis of P. falciparum infection.

  12. Assessing parasite clearance during uncomplicated Plasmodium falciparum infection treated with artesunate monotherapy in Suriname

    PubMed Central

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

    2016-01-01

    Background Artemisinin resistance in Plasmodium falciparum is suspected when the day 3 parasitemia is >10% when treated with artemisinin-based combination therapy or if >10% of patients treated with artemisinin-based combination therapy or artesunate monotherapy harbored parasites with half-lives ≥5 hours. Hence, a single-arm prospective efficacy trial was conducted in Suriname for uncomplicated P. falciparum infection treated with artesunate-based monotherapy for 3 days assessing day 3 parasitemia, treatment outcome after 28 days, and parasite half-life. Methods The study was conducted in Paramaribo, the capital of Suriname, from July 2013 until July 2014. Patients with uncomplicated Plasmodium falciparum infection were included and received artesunate mono-therapy for three days. Day 3 parasitaemia, treatment outcome after 28 days and parasite half-life were determined. The latter was assessed with the parasite clearance estimator from the WorldWide Antimalarial Resistance Network (WWARN). Results Thirty-nine patients were included from July 2013 until July 2014. The day 3 parasitemia was 10%. Eight patients (20.5%) could be followed up until day 28 and showed adequate clinical and parasitological response. Parasite half-life could only be determined from ten data series (25.7%). The median parasite half-life was 5.16 hours, and seven of these data series had a half-life ≥5 hours, still comprising 17.9% of the total data series. Conclusion The low follow-up rate and the limited analyzable data series preclude clear conclusions about the efficacy of artesunate monotherapy in Suriname and the parasite half-life, respectively. The emergence of at least 17.9% of data series with a parasite half-life ≥5 hours supports the possible presence of artemisinin resistance. PMID:27920563

  13. FRET Imaging of Hemoglobin Concentration in Plasmodium falciparum-Infected Red Cells

    PubMed Central

    Esposito, Alessandro; Tiffert, Teresa; Mauritz, Jakob M. A.; Schlachter, Simon; Bannister, Lawrence H.; Kaminski, Clemens F.; Lew, Virgilio L.

    2008-01-01

    Background During its intraerythrocytic asexual reproduction cycle Plasmodium falciparum consumes up to 80% of the host cell hemoglobin, in large excess over its metabolic needs. A model of the homeostasis of falciparum-infected red blood cells suggested an explanation based on the need to reduce the colloid-osmotic pressure within the host cell to prevent its premature lysis. Critical for this hypothesis was that the hemoglobin concentration within the host cell be progressively reduced from the trophozoite stage onwards. Methodology/Principal Findings The experiments reported here were designed to test this hypothesis by direct measurements of the hemoglobin concentration in live, infected red cells. We developed a novel, non-invasive method to quantify the hemoglobin concentration in single cells, based on Förster resonance energy transfer between hemoglobin molecules and the fluorophore calcein. Fluorescence lifetime imaging allowed the quantitative mapping of the hemoglobin concentration within the cells. The average fluorescence lifetimes of uninfected cohorts was 270±30 ps (mean±SD; N = 45). In the cytoplasm of infected cells the fluorescence lifetime of calcein ranged from 290±20 ps for cells with ring stage parasites to 590±13 ps and 1050±60 ps for cells with young trophozoites and late stage trophozoite/ early schizonts, respectively. This was equivalent to reductions in hemoglobin concentration spanning the range from 7.3 to 2.3 mM, in line with the model predictions. An unexpected ancillary finding was the existence of a microdomain under the host cell membrane with reduced calcein quenching by hemoglobin in cells with mature trophozoite stage parasites. Conclusions/Significance The results support the predictions of the colloid-osmotic hypothesis and provide a better understanding of the homeostasis of malaria-infected red cells. In addition, they revealed the existence of a distinct peripheral microdomain in the host cell with limited access

  14. An Intensive Longitudinal Cohort Study of Malian Children and Adults Reveals No Evidence of Acquired Immunity to Plasmodium falciparum Infection

    PubMed Central

    Tran, Tuan M.; Li, Shanping; Doumbo, Safiatou; Doumtabe, Didier; Huang, Chiung-Yu; Dia, Seydou; Bathily, Aboudramane; Sangala, Jules; Kone, Younoussou; Traore, Abdrahamane; Niangaly, Moussa; Dara, Charles; Kayentao, Kassoum; Ongoiba, Aissata; Doumbo, Ogobara K.; Traore, Boubacar; Crompton, Peter D.

    2013-01-01

    Background In experimental models of human and mouse malaria, sterilizing liver stage immunity that blocks progression of Plasmodium infection to the symptomatic blood stage can be readily demonstrated. However, it remains unclear whether individuals in malaria-endemic areas acquire such immunity. Methods In Mali, 251 healthy children and adults aged 4–25 years who were free of blood-stage Plasmodium infection by polymerase chain reaction (PCR) were enrolled in a longitudinal study just prior to an intense 6-month malaria season. Subsequent clinical malaria episodes were detected by weekly active surveillance and self-referral. Asymptomatic P. falciparum infections were detected by blood-smear microscopy and PCR analysis of dried blood spots that had been collected every 2 weeks for 7 months. Results As expected, the risk of clinical malaria decreased with increasing age (log-rank test, P = .0038). However, analysis of PCR data showed no age-related differences in P. falciparum infection risk (log-rank test, P = .37). Conclusions Despite years of exposure to intense P. falciparum transmission, there is no evidence of acquired, sterile immunity to P. falciparum infection in this population, even as clinical immunity to blood-stage malaria is clearly acquired. Understanding why repeated P. falciparum infections do not induce sterile protection may lead to insights for developing vaccines that target the liver stage in malaria-endemic populations. PMID:23487390

  15. Cytoadhesion of Plasmodium falciparum-infected erythrocytes and the infected placenta: a two-way pathway.

    PubMed

    Costa, F T M; Avril, M; Nogueira, P A; Gysin, J

    2006-12-01

    Malaria is undoubtedly the world's most devastating parasitic disease, affecting 300 to 500 million people every year. Some cases of Plasmodium falciparum infection progress to the deadly forms of the disease responsible for 1 to 3 million deaths annually. P. falciparum-infected erythrocytes adhere to host receptors in the deep microvasculature of several organs. The cytoadhesion of infected erythrocytes to placental syncytiotrophoblast receptors leads to pregnancy-associated malaria (PAM). This specific maternal-fetal syndrome causes maternal anemia, low birth weight and the death of 62,000 to 363,000 infants per year in sub-Saharan Africa, and thus has a poor outcome for both mother and fetus. However, PAM and non-PAM parasites have been shown to differ antigenically and genetically. After multiple pregnancies, women from different geographical areas develop adhesion-blocking antibodies that protect against placental parasitemia and clinical symptoms of PAM. The recent description of a new parasite ligand encoded by the var2CSA gene as the only gene up-regulated in PAM parasites renders the development of an anti-PAM vaccine more feasible. The search for a vaccine to prevent P. falciparum sequestration in the placenta by eliciting adhesion-blocking antibodies and a cellular immune response, and the development of new methods for evaluating such antibodies should be key priorities in mother-child health programs in areas of endemic malaria. This review summarizes the main molecular, immunological and physiopathological aspects of PAM, including findings related to new targets in the P. falciparum var gene family. Finally, we focus on a new methodology for mimicking cytoadhesion under blood flow conditions in human placental tissue.

  16. Therapeutic efficacy of chloroquine and sulfadoxine/pyrimethamine against Plasmodium falciparum infection in Somalia.

    PubMed Central

    Warsame, M.; Abdillahi, A.; Duale, O. Nur; Ismail, A. Nur; Hassan, A. M.; Mohamed, A.; Warsame, A.

    2002-01-01

    OBJECTIVE: To assess the efficacy of chloroquine and sulfadoxine/pyrimethamine in the treatment of uncomplicated Plasmodium falciparum infections in Somalia. METHODS: Patients with clinical malaria in Merca, an area of high transmission of the disease, were treated with the standard regimens of chloroquine (25 mg/kg) or sulfadoxine/pyrimethamine (25 mg sulfadoxine and 1.25 mg pyrimethamine per kg). Similar patients in Gabiley, an area of low transmission, received the standard regimen of chloroquine. The clinical and parasitological responses were monitored for 14 days. FINDINGS: Chloroquine treatment resulted in clinical failure in 33% (n = 60) and 51% (n = 49) of the patients in Merca and Gabiley respectively. There were corresponding parasitological failures of 77% RII/RIII and 35% RII/RIII. Patients who experienced clinical failure had significantly higher initial parasitaemia than those in whom there was an adequate clinical response, both in Merca (t = 2.2; P t = 2.8; P n = 50) of the patients achieved an adequate clinical response despite a parasitological failure rate of 76% RII/RIII. CONCLUSION: Chloroquine should no longer be considered adequate for treating clinical falciparum malaria in vulnerable groups in the areas studied. Doubts about the therapeutic life of sulfadoxine/pyrimethamine in relation to malaria are raised by the high levels of resistance in the Merca area and underline the need to identify suitable alternatives. PMID:12378287

  17. 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

  18. Optimization and inhibition of the adherent ability of Plasmodium falciparum-infected erythrocytes.

    PubMed

    Smith, H; Crandall, I; Prudhomme, J; Sherman, I W

    1992-01-01

    The vast majority of the 1-2 million malaria associated deaths that occur each year are due to anemia and cerebral malaria (the attachment of erythrocytes containing mature forms of Plasmodium falciparum to the endothelial cells that line the vascular beds of the brain). A "model system" for the study of cerebral malaria employs amelanotic melanoma cells as the "target" cells in an in vitro cytoadherence assay. Using this model system we determined that the optimum pH for adherence is 6.6 to 6.8, that high concentrations of Ca2+ (50mM) result in increased levels of binding, and that the type of buffer used influences adherence (Bis Tris > MOPS > HEPES > PIPES). We also observed that the ability of infected erythrocytes to cytoadhere varied from (erythrocyte) donor to donor. We have produced murine monoclonal antibodies against P. falciparum-infected red cells which recognize modified forms of human band 3; these inhibit the adherence of infected erythrocytes to melanoma cells in a dose-responsive fashion. Antimalarials (chloroquine, quinacrine, mefloquine, artemisinin), on the other hand, affected adherence in an indirect fashion i.e. since cytoadherence is due, in part, to the presence of knobs on the surface of the infected erythrocyte, and knob formation is dependent on intracellular parasite growth, when plasmodial development is inhibited so is knob production, and consequently adherence is ablated.

  19. Comparison of PCR-based detection of Plasmodium falciparum infections based on single and multicopy genes

    PubMed Central

    Oyedeji, Segun I; Awobode, Henrietta O; Monday, Gamaliel C; Kendjo, Eric; Kremsner, Peter G; Kun, Jürgen F

    2007-01-01

    PCR-based assays are the most sensitive and specific methods to detect malaria parasites. This study compared the diagnostic accuracy of three PCR-based assays that do not only differ in their sequence target, but also in the number of copies of their target region, for the detection of Plasmodium falciparum in 401 individuals living in a malaria-endemic area in Nigeria. Compared to a composite reference generated from results of all the 3 PCR assays, the stevor gene amplification had a sensitivity of 100% (Kappa = 1; 95% CI = 1.000–1.000), 83% (Kappa = 0.718; 95% CI = 0.648–0.788) by SSUrRNA gene PCR and 71% (Kappa = 0.552; 95% CI = 0.478–0.627) by the msa-2 gene amplification. Results from this study indicate that the stevor gene amplification is the most sensitive technique for the detection of P. falciparum. This assay may be an important reference standard, especially when a confirmatory technique with high sensitivity and specificity is needed for ruling out P. falciparum infection. PMID:17705826

  20. Multifaceted Role of Heme during Severe Plasmodium falciparum Infections in India

    PubMed Central

    Dalko, Esther; Das, Bidyut; Herbert, Fabien; Fesel, Constantin; Pathak, Sulabha; Tripathy, Rina; Cazenave, Pierre-André; Ravindran, Balachandran; Sharma, Shobhona

    2015-01-01

    Several immunomodulatory factors are involved in malaria pathogenesis. Among them, heme has been shown to play a role in the pathophysiology of severe malaria in rodents, but its role in human severe malaria remains unclear. Circulating levels of total heme and its main scavenger, hemopexin, along with cytokine/chemokine levels and biological parameters, including hemoglobin and creatinine levels, as well as transaminase activities, were measured in the plasma of 237 Plasmodium falciparum-infected patients living in the state of Odisha, India, where malaria is endemic. All patients were categorized into well-defined groups of mild malaria, cerebral malaria (CM), or severe noncerebral malaria, which included acute renal failure (ARF) and hepatopathy. Our results show a significant increase in total plasma heme levels with malaria severity, especially for CM and malarial ARF. Spearman rank correlation and canonical correlation analyses have shown a correlation between total heme, hemopexin, interleukin-10, tumor necrosis factor alpha, gamma interferon-induced protein 10 (IP-10), and monocyte chemotactic protein 1 (MCP-1) levels. In addition, canonical correlations revealed that heme, along with IP-10, was associated with the CM pathophysiology, whereas both IP-10 and MCP-1 together with heme discriminated ARF. Altogether, our data indicate that heme, in association with cytokines and chemokines, is involved in the pathophysiology of both CM and ARF but through different mechanisms. PMID:26169278

  1. Multifaceted Role of Heme during Severe Plasmodium falciparum Infections in India.

    PubMed

    Dalko, Esther; Das, Bidyut; Herbert, Fabien; Fesel, Constantin; Pathak, Sulabha; Tripathy, Rina; Cazenave, Pierre-André; Ravindran, Balachandran; Sharma, Shobhona; Pied, Sylviane

    2015-10-01

    Several immunomodulatory factors are involved in malaria pathogenesis. Among them, heme has been shown to play a role in the pathophysiology of severe malaria in rodents, but its role in human severe malaria remains unclear. Circulating levels of total heme and its main scavenger, hemopexin, along with cytokine/chemokine levels and biological parameters, including hemoglobin and creatinine levels, as well as transaminase activities, were measured in the plasma of 237 Plasmodium falciparum-infected patients living in the state of Odisha, India, where malaria is endemic. All patients were categorized into well-defined groups of mild malaria, cerebral malaria (CM), or severe noncerebral malaria, which included acute renal failure (ARF) and hepatopathy. Our results show a significant increase in total plasma heme levels with malaria severity, especially for CM and malarial ARF. Spearman rank correlation and canonical correlation analyses have shown a correlation between total heme, hemopexin, interleukin-10, tumor necrosis factor alpha, gamma interferon-induced protein 10 (IP-10), and monocyte chemotactic protein 1 (MCP-1) levels. In addition, canonical correlations revealed that heme, along with IP-10, was associated with the CM pathophysiology, whereas both IP-10 and MCP-1 together with heme discriminated ARF. Altogether, our data indicate that heme, in association with cytokines and chemokines, is involved in the pathophysiology of both CM and ARF but through different mechanisms. Copyright © 2015, American Society for Microbiology. All Rights Reserved.

  2. Malaria’s Deadly Grip: Cytoadhesion of Plasmodium falciparum Infected Erythrocytes

    PubMed Central

    Smith, Joseph D.; Rowe, J. Alexandra; Higgins, Matthew K.; Lavstsen, Thomas

    2013-01-01

    Summary Cytoadhesion of Plasmodium falciparum infected erythrocytes to host microvasculature is a key virulence determinant. Parasite binding is mediated by a large family of clonally variant adhesion proteins, termed P. falciparum erythrocyte membrane protein 1 (PfEMP1), encoded by var genes and expressed at the infected-erythrocyte surface. Although PfEMP1 proteins have extensively diverged under opposing selection pressure to maintain ligand binding while avoiding antibody-mediated detection, recent work has revealed they can be classified into different groups based on chromosome location and domain composition. This grouping reflects functional specialization of PfEMP1 proteins for different human host and microvascular binding niches and appears to be maintained by gene recombination hierarchies. In one extreme, a specific PfEMP1 variant is associated with placental binding and malaria during pregnancy, while other PfEMP1 subtypes appear to be specialized for infection of malaria naïve hosts. Here, we discuss recent findings on the origins and evolution of the var gene family, the structure-function of PfEMP1 proteins, and a distinct subset of PfEMP1 variants that have been associated with severe childhood malaria. PMID:23957661

  3. Exported Epoxide Hydrolases Modulate Erythrocyte Vasoactive Lipids during Plasmodium falciparum Infection

    PubMed Central

    Dalmia, Varun K.

    2016-01-01

    ABSTRACT Erythrocytes are reservoirs of important epoxide-containing lipid signaling molecules, including epoxyeicosatrienoic acids (EETs). EETs function as vasodilators and anti-inflammatory modulators in the bloodstream. Bioactive EETs are hydrolyzed to less active diols (dihydroxyeicosatrienoic acids) by epoxide hydrolases (EHs). The malaria parasite Plasmodium falciparum infects host red blood cells (RBCs) and exports hundreds of proteins into the RBC compartment. In this study, we show that two parasite epoxide hydrolases, P. falciparum epoxide hydrolases 1 (PfEH1) and 2 (PfEH2), both with noncanonical serine nucleophiles, are exported to the periphery of infected RBCs. PfEH1 and PfEH2 were successfully expressed in Escherichia coli, and they hydrolyzed physiologically relevant erythrocyte EETs. Mutations in active site residues of PfEH1 ablated the ability of the enzyme to hydrolyze an epoxide substrate. Overexpression of PfEH1 or PfEH2 in parasite-infected RBCs resulted in a significant alteration in the epoxide fatty acids stored in RBC phospholipids. We hypothesize that the parasite disruption of epoxide-containing signaling lipids leads to perturbed vascular function, creating favorable conditions for binding and sequestration of infected RBCs to the microvascular endothelium. PMID:27795395

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

    PubMed Central

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

    2013-01-01

    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 vascular 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. PMID:21743938

  5. Lipid traffic between high density lipoproteins and Plasmodium falciparum-infected red blood cells

    PubMed Central

    1991-01-01

    Several intraerythrocytic growth cycles of Plasmodium falciparum could be achieved in vitro using a serum free medium supplemented only with a human high density lipoprotein (HDL) fraction (d = 1.063-1.210). The parasitemia obtained was similar to that in standard culture medium containing human serum. The parasite development was incomplete with the low density lipoprotein (LDL) fraction and did not occur with the VLDL fraction. The lipid traffic from HDL to the infected erythrocytes was demonstrated by pulse labeling experiments using HDL loaded with either fluorescent NBD-phosphatidylcholine (NBD-PC) or radioactive [3H]palmitoyl-PC. At 37 degrees C, the lipid probes rapidly accumulated in the infected cells. After incubation in HDL medium containing labeled PC, a subsequent incubation in medium with either an excess of native HDL or 20% human serum induced the disappearance of the label from the erythrocyte plasma membrane but not from the intraerythrocytic parasite. Internalization of lipids did not occur at 4 degrees C. The mechanism involved a unidirectional flux of lipids but no endocytosis. The absence of labeling of P. falciparum, with HDL previously [125I]iodinated on their apolipoproteins or with antibodies against the apolipoproteins AI and AII by immunofluorescence and immunoblotting, confirmed that no endocytosis of the HDL was involved. A possible pathway of lipid transport could be a membrane flux since fluorescence videomicroscopy showed numerous organelles labeled with NBD-PC moving between the erythrocyte and the parasitophorous membranes. TLC analysis showed that a partial conversion of the PC to phosphatidylethanolamine was observed in P. falciparum-infected red cells after pulse with [3H]palmitoyl-PC-HDL. The intensity of the lipid traffic was stage dependent with a maximum at the trophozoite and young schizont stages (38th h of the erythrocyte life cycle). We conclude that the HDL fraction appears to be a major lipid source for Plasmodium

  6. 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

  7. Malaria in pregnancy in rural Mozambique: the role of parity, submicroscopic and multiple Plasmodium falciparum infections.

    PubMed

    Saute, Francisco; Menendez, Clara; Mayor, Alfredo; Aponte, John; Gomez-Olive, Xavier; Dgedge, Martinho; Alonso, Pedro

    2002-01-01

    Falciparum malaria affects pregnant women, especially primigravidae, but before malaria control programmes targeted to them can be designed, a description of the frequency and parity pattern of the infection is needed. There is little information on the frequency and effect of submicroscopic malaria infection, as well as on multiplicity of Plasmodium falciparum genotypes in pregnancy. This study aimed to describe the prevalence of malaria parasitaemia and anaemia and their relation to parity and age in pregnant women, during two malaria transmission seasons in a rural area of southern Mozambique. It also tried to assess the frequency and effect on anaemia of submicroscopic and multiple falciparum infections. A total of 686 pregnant women were enrolled in three cross-sectional community-based surveys during different transmission seasons in rural southern Mozambique. In each survey a questionnaire was administered on previous parity history, the gestational age was assessed, the axillary temperature recorded and both haematocrit and malaria parasitaemia were determined. We used polymerase chain reaction (PCR) and restriction fragment length polymorphism (RFLP) analysis to determine submicroscopic and multiple P. falciparum infections in a subsample of women. A total of 156 women (23%) had microscopic parasitaemia, of which 144 (92%) were asexual forms of P. falciparum. The prevalence of clinical malaria was 18 of 534 (3%), that of anaemia, 382 of 649 (59%). In a multivariate analysis age but not parity was associated with an increased risk of microscopic parasitaemia. Anaemia was associated with microscopic P. falciparum parasitaemia. Both malaria parasitaemia and anaemia were more frequent during the rainy season. Although not statistically significant, submicroscopic infections tended to be more frequent among grand-multiparous pregnant women. Subpatent infections were not associated with increased anaemia. Multiplicity of infection was not associated with either

  8. Effects of sevuparin on rosette formation and cytoadherence of Plasmodium falciparum infected erythrocytes

    PubMed Central

    Saiwaew, Somporn; Sritabal, Juntima; Piaraksa, Nattaporn; Keayarsa, Srisuda; Ruengweerayut, Ronnatrai; Utaisin, Chirapong; Sila, Patima; Niramis, Rangsan; Udomsangpetch, Rachanee; Charunwatthana, Prakaykaew; Pongponratn, Emsri; Pukrittayakamee, Sasithon; Leitgeb, Anna M.; Wahlgren, Mats; Lee, Sue J.; Day, Nicholas P. J.; White, Nicholas J.; Dondorp, Arjen M.; Chotivanich, Kesinee

    2017-01-01

    In severe falciparum malaria cytoadherence of parasitised red blood cells (PRBCs) to vascular endothelium (causing sequestration) and to uninfected red cells (causing rosette formation) contribute to microcirculatory flow obstruction in vital organs. Heparin can reverse the underlying ligand-receptor interactions, but may increase the bleeding risks. As a heparin-derived polysaccharide, sevuparin has been designed to retain anti-adhesive properties, while the antithrombin-binding domains have been eliminated, substantially diminishing its anticoagulant activity. Sevuparin has been evaluated recently in patients with uncomplicated falciparum malaria, and is currently investigated in a clinical trial for sickle cell disease. The effects of sevuparin on rosette formation and cytoadherence of Plasmodium falciparum isolates from Thailand were investigated. Trophozoite stages of P. falciparum-infected RBCs (Pf-iRBCs) were cultured from 49 patients with malaria. Pf-iRBCs were treated with sevuparin at 37°C and assessed in rosetting and in cytoadhesion assays with human dermal microvascular endothelial cells (HDMECs) under static and flow conditions. The proportion of Pf-iRBCs forming rosettes ranged from 6.5% to 26.0% (median = 12.2%). Rosetting was dose dependently disrupted by sevuparin (50% disruption by 250 μg/mL). Overall 57% of P. falciparum isolates bound to HDMECs under static conditions; median (interquartile range) Pf-iRBC binding was 8.5 (3.0–38.0) Pf-iRBCs/1000 HDMECs. Sevuparin in concentrations ≥ 100 μg/mL inhibited cytoadherence. Sevuparin disrupts P. falciparum rosette formation in a dose dependent manner and inhibits cytoadherence to endothelial cells. The data support assessment of sevuparin as an adjunctive treatment to the standard therapy in severe falciparum malaria. PMID:28249043

  9. Effects of sevuparin on rosette formation and cytoadherence of Plasmodium falciparum infected erythrocytes.

    PubMed

    Saiwaew, Somporn; Sritabal, Juntima; Piaraksa, Nattaporn; Keayarsa, Srisuda; Ruengweerayut, Ronnatrai; Utaisin, Chirapong; Sila, Patima; Niramis, Rangsan; Udomsangpetch, Rachanee; Charunwatthana, Prakaykaew; Pongponratn, Emsri; Pukrittayakamee, Sasithon; Leitgeb, Anna M; Wahlgren, Mats; Lee, Sue J; Day, Nicholas P J; White, Nicholas J; Dondorp, Arjen M; Chotivanich, Kesinee

    2017-01-01

    In severe falciparum malaria cytoadherence of parasitised red blood cells (PRBCs) to vascular endothelium (causing sequestration) and to uninfected red cells (causing rosette formation) contribute to microcirculatory flow obstruction in vital organs. Heparin can reverse the underlying ligand-receptor interactions, but may increase the bleeding risks. As a heparin-derived polysaccharide, sevuparin has been designed to retain anti-adhesive properties, while the antithrombin-binding domains have been eliminated, substantially diminishing its anticoagulant activity. Sevuparin has been evaluated recently in patients with uncomplicated falciparum malaria, and is currently investigated in a clinical trial for sickle cell disease. The effects of sevuparin on rosette formation and cytoadherence of Plasmodium falciparum isolates from Thailand were investigated. Trophozoite stages of P. falciparum-infected RBCs (Pf-iRBCs) were cultured from 49 patients with malaria. Pf-iRBCs were treated with sevuparin at 37°C and assessed in rosetting and in cytoadhesion assays with human dermal microvascular endothelial cells (HDMECs) under static and flow conditions. The proportion of Pf-iRBCs forming rosettes ranged from 6.5% to 26.0% (median = 12.2%). Rosetting was dose dependently disrupted by sevuparin (50% disruption by 250 μg/mL). Overall 57% of P. falciparum isolates bound to HDMECs under static conditions; median (interquartile range) Pf-iRBC binding was 8.5 (3.0-38.0) Pf-iRBCs/1000 HDMECs. Sevuparin in concentrations ≥ 100 μg/mL inhibited cytoadherence. Sevuparin disrupts P. falciparum rosette formation in a dose dependent manner and inhibits cytoadherence to endothelial cells. The data support assessment of sevuparin as an adjunctive treatment to the standard therapy in severe falciparum malaria.

  10. Submicroscopic Plasmodium falciparum Infections Are Associated With Maternal Anemia, Premature Births, and Low Birth Weight.

    PubMed

    Cottrell, Gilles; Moussiliou, Azizath; Luty, Adrian J F; Cot, Michel; Fievet, Nadine; Massougbodji, Achille; Deloron, Philippe; Tuikue Ndam, Nicaise

    2015-05-15

    Molecular, as opposed to microscopic, detection measures the real prevalence of Plasmodium falciparum infections. Such occult infections are common during pregnancy but their impact on pregnancy outcomes is unclear. We performed a longitudinal study to describe that impact. In a cohort of 1037 Beninese pregnant women, we used ultrasound to accurately estimate gestational ages. Infection with P. falciparum, hemoglobin concentration, use of intermittent preventive treatment during pregnancy (IPTp) for malaria, and other parameters were recorded during pregnancy. Using multivariate analyses, we evaluated the impact of submicroscopic infections on maternal anemia, premature birth, and low birth weight. At inclusion, polymerase chain reaction (PCR) and microscopy detected infection in 40% and 16% of women, respectively. The proportion infected declined markedly after 2 doses of IPTp but rebounded to 34% (by PCR) at delivery. Submicroscopic infections during pregnancy were associated with lower mean hemoglobin irrespective of gravidity, and with increased anemia risk in primigravidae (odds ratio [OR], 2.23; 95% confidence interval [CI], .98-5.07). Prospectively, submicroscopic infections at inclusion were associated with significantly increased risks of low birth weight in primigravidae (OR, 6.09; 95% CI, 1.16-31.95) and premature births in multigravidae (OR, 2.25; 95% CI, 1.13-4.46). In this detailed longitudinal study, we document the deleterious impact of submicroscopic P. falciparum parasitemia during pregnancy on multiple pregnancy outcomes. Parasitemia occurs frequently during pregnancy, but routine microscopic and rapid diagnostic tests fail to detect the vast majority of episodes. Our findings imply caution in any revision of the current strategies for prevention of pregnancy-associated malaria. © The Author 2015. Published by Oxford University Press on behalf of the Infectious Diseases Society of America. All rights reserved. For Permissions, please e

  11. Cytochrome b gene quantitative PCR for diagnosing Plasmodium falciparum infection in travelers.

    PubMed

    Farrugia, Cécile; Cabaret, Odile; Botterel, Françoise; Bories, Christian; Foulet, Françoise; Costa, Jean-Marc; Bretagne, Stéphane

    2011-06-01

    A cytochrome b (cytb) gene quantitative PCR (qPCR) assay was developed to diagnose malaria in travelers. First, manual and automated DNA extractions were compared and automated DNA extraction of 400 μl of blood was found to be more efficient. Sensitivity was estimated using the WHO international standard for Plasmodium falciparum DNA and compared to that of a previously published qPCR targeting the 18S rRNA coding gene (18S qPCR). The limit of detection of the cytb qPCR assay was 20 DNA copies (i.e., 1 parasite equivalent) per 400 μl of extracted whole blood and was comparable for the two qPCR assays. Both qPCR assays were used on blood samples from 265 consecutive patients seen for suspicion of malaria. There were no microscopy-positive and qPCR-negative samples. Positive cytb qPCR results were observed for 51 samples, and all but 1 were also 18S qPCR positive. Eight (16%) of these 51 samples were negative by microscopic examination. The 8 cytb qPCR-positive and microscopy-negative samples were from African patients, 3 of whom had received antimalarial drugs. Three non-P. falciparum infections were correctly identified using an additional qPCR assay. The absence of PCR inhibitors was tested for by the use of an internal control of mouse DNA to allow reliable quantification of circulating DNA. The high analytical sensitivity of both qPCR assays combined with automated DNA extraction supports its use as a laboratory tool for diagnosis and parasitemia determination in emergencies. Whether to treat qPCR-positive and microscopy-negative patients remains to be determined.

  12. An automated method for determining the cytoadhesion of Plasmodium falciparum-infected erythrocytes to immobilized cells.

    PubMed

    Hempel, Casper; Boisen, Ida M; Efunshile, Akinwale; Kurtzhals, Jørgen A L; Staalsø, Trine

    2015-03-14

    Plasmodium falciparum exports antigens to the surface of infected erythrocytes causing cytoadhesion to the host vasculature. This is central in malaria pathogenesis but in vitro studies of cytoadhesion rely mainly on manual counting methods. The current study aimed at developing an automated high-throughput method for this purpose utilizing the pseudoperoxidase activity of intra-erythrocytic haemoglobin. Chinese hamster ovary (CHO) cells were grown to confluence in chamber slides and microtiter plates. Cytoadhesion of co-cultured P. falciparum, selected for binding to CHO cells, was quantified by microscopy of Giemsa-stained chamber slides. In the automated assay, binding was quantified spectrophotometrically in microtiter plates after cell lysis using tetramethylbenzidine as peroxidase-catalysed substrate. The relevance of the method for binding studies was assessed using: i) binding of P. falciparum-infected erythrocytes to CHO cells over-expressing chondroitin sulfate A and ii) CHO cells transfected with CD36. Binding of infected erythrocytes including field isolates to primary endothelial cells was also performed. Data was analysed using linear regression and Bland-Altman plots. The manual and automated quantification showed strong, positive correlation (r(2) = 0.959, p <0.001) and with similar detection limit and precision. The automated assay showed the expected dose-dependent reduction in binding to CHO cells when blocking with soluble chondroitin sulfate A or anti-CD36 antibody. Quantification of binding to endothelial cells showed clear distinction between selected vs. non-selected parasite lines. Importantly, the assay was sufficiently sensitive to detect adhesion of field isolates to endothelial cells. The assay is simple and in a reproducible manner quantifies erythrocyte adhesion to several types of immobilized cells.

  13. 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

    2002-09-03

    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.

  14. Plasmodium falciparum Infection Status among Children with Schistosoma in Sub-Saharan Africa: A Systematic Review and Meta-analysis

    PubMed Central

    Degarege, Abraham; Degarege, Dawit; Veledar, Emir; Erko, Berhanu; Nacher, Mathieu; Beck-Sague, Consuelo M.; Madhivanan, Purnima

    2016-01-01

    Background It has been suggested that Schistosoma infection may be associated with Plasmodium falciparum infection or related reduction in haemoglobin level, but the nature of this interaction remains unclear. This systematic review synthesized evidence on the relationship of S. haematobium or S. mansoni infection with the occurrence of P. falciparum malaria, Plasmodium density and related reduction in haemoglobin level among children in sub-Saharan Africa (SSA). Methodology/Principal findings A systematic review in according with PRISMA guidelines was conducted. All published articles available in PubMed, Embase, Cochrane library and CINAHL databases before May 20, 2015 were searched without any limits. Two reviewers independently screened, reviewed and assessed all the studies. Cochrane Q and Moran’s I2 were used to assess heterogeneity and the Egger test was used to examine publication bias. The summary odds ratio (OR), summary regression co-efficient (β) and 95% confidence intervals (CI) were estimated using a random-effects model. Out of 2,920 citations screened, 12 articles (five cross-sectional, seven prospective cohort) were eligible to be included in the systematic review and 11 in the meta-analysis. The 12 studies involved 9,337 children in eight SSA countries. Eight studies compared the odds of asymptomatic/uncomplicated P. falciparum infection, two studies compared the incidence of uncomplicated P. falciparum infection, six studies compared P. falciparum density and four studies compared mean haemoglobin level between children infected and uninfected with S. haematobium or S. mansoni. Summary estimates of the eight studies based on 6,018 children showed a higher odds of asymptomatic/uncomplicated P. falciparum infection in children infected with S. mansoni or S. haematobium compared to those uninfected with Schistosoma (summary OR: 1.82; 95%CI: 1.41, 2.35; I2: 52.3%). The increase in odds of asymptomatic/uncomplicated P. falciparum infection among

  15. A lethal case of Plasmodium falciparum infection in a young patient with end-stage renal failure who underwent regular hemodialysis.

    PubMed

    Hartopo, Anggoro Budi; Wijisaksono, Doni Priambodo

    2010-01-01

    Acute renal failure associated with Plasmodium falciparum infection is already well recognized. Nevertheless, end-stage chronic renal failure and falciparum malaria comorbidity is a rare condition. We report a case of Plasmodium falciparum infection in a young male Javanese patient with end-stage chronic renal failure who underwent regular hemodialysis. This rare comorbidity led to rapid deterioration of consciousness and metabolic disturbances which had already existed in end-stage renal failure. Because of the immunosuppressive condition due to organ failure, the patient did not survive despite anti-malarial chemotherapy.

  16. Bone marrow suppression and severe anaemia associated with persistent Plasmodium falciparum infection in African children with microscopically undetectable parasitaemia

    PubMed Central

    Helleberg, Marie; Goka, Bamenla Q; Akanmori, Bartholomew D; Obeng-Adjei, George; Rodriques, Onike; Kurtzhals, Jorgen AL

    2005-01-01

    Background Severe anaemia can develop in the aftermath of Plasmodium falciparum malaria because of protracted bone marrow suppression, possibly due to residual subpatent parasites. Materials and methods Blood was collected from patients with recent malaria and negative malaria microscopy. Detection of the Plasmodium antigens, lactate dehydrogenase (Optimal®), aldolase and histidine rich protein 2 (Now malaria®) were used to differentiate between patients with (1) no malaria, (2) recent cleared malaria, (3) persistent P. falciparum infection. Red cell distribution width (RDW), plasma levels of soluble transferrin receptor (sTfR) and erythropoietin (EPO) were measured as markers of erythropoiesis. Interleukin (IL) 10 and tumour necrosis factor (TNF)α were used as inflammation markers. Results EPO was correlated with haemoglobin, irrespective of malaria (R = -0.36, P < 0.001). Persistent P. falciparum infection, but not recent malaria without residual parasites, was associated with bone marrow suppression i.e., low RDW (P < 0.001 vs. P = 0.56) and sTfR (P = 0.02 vs. P = 0.36). TNF-α and IL-10 levels were not associated with bone marrow suppression. Conclusion In the treatment of malaria, complete eradication of parasites may prevent subsequent development of anaemia. Severely anaemic children may benefit from antimalarial treatment if antigen tests are positive, even when no parasites can be demonstrated by microscopy. PMID:16321150

  17. Severe anaemia associated with Plasmodium falciparum infection in children: consequences for additional blood sampling for research.

    PubMed

    Kuijpers, Laura Maria Francisca; Maltha, Jessica; Guiraud, Issa; Kaboré, Bérenger; Lompo, Palpouguini; Devlieger, Hugo; Van Geet, Chris; Tinto, Halidou; Jacobs, Jan

    2016-06-02

    Plasmodium falciparum infection may cause severe anaemia, particularly in children. When planning a diagnostic study on children suspected of severe malaria in sub-Saharan Africa, it was questioned how much blood could be safely sampled; intended blood volumes (blood cultures and EDTA blood) were 6 mL (children aged <6 years) and 10 mL (6-12 years). A previous review [Bull World Health Organ. 89: 46-53. 2011] recommended not to exceed 3.8 % of total blood volume (TBV). In a simulation exercise using data of children previously enrolled in a study about severe malaria and bacteraemia in Burkina Faso, the impact of this 3.8 % safety guideline was evaluated. For a total of 666 children aged >2 months to <12 years, data of age, weight and haemoglobin value (Hb) were available. For each child, the estimated TBV (TBVe) (mL) was calculated by multiplying the body weight (kg) by the factor 80 (ml/kg). Next, TBVe was corrected for the degree of anaemia to obtain the functional TBV (TBVf). The correction factor consisted of the rate 'Hb of the child divided by the reference Hb'; both the lowest ('best case') and highest ('worst case') reference Hb values were used. Next, the exact volume that a 3.8 % proportion of this TBVf would present was calculated and this volume was compared to the blood volumes that were intended to be sampled. When applied to the Burkina Faso cohort, the simulation exercise pointed out that in 5.3 % (best case) and 11.4 % (worst case) of children the blood volume intended to be sampled would exceed the volume as defined by the 3.8 % safety guideline. Highest proportions would be in the age groups 2-6 months (19.0 %; worst scenario) and 6 months-2 years (15.7 %; worst case scenario). A positive rapid diagnostic test for P. falciparum was associated with an increased risk of violating the safety guideline in the worst case scenario (p = 0.016). Blood sampling in children for research in P. falciparum endemic settings may easily violate

  18. A sensitive, specific and reproducible real-time polymerase chain reaction method for detection of Plasmodium vivax and Plasmodium falciparum infection in field-collected anophelines.

    PubMed

    Bickersmith, Sara A; Lainhart, William; Moreno, Marta; Chu, Virginia M; Vinetz, Joseph M; Conn, Jan E

    2015-06-01

    We describe a simple method for detection of Plasmodium vivax and Plasmodium falciparum infection in anophelines using a triplex TaqMan real-time polymerase chain reaction (PCR) assay (18S rRNA). We tested the assay on Anopheles darlingi and Anopheles stephensi colony mosquitoes fed with Plasmodium-infected blood meals and in duplicate on field collected An. darlingi. We compared the real-time PCR results of colony-infected and field collected An. darlingi, separately, to a conventional PCR method. We determined that a cytochrome b-PCR method was only 3.33% as sensitive and 93.38% as specific as our real-time PCR assay with field-collected samples. We demonstrate that this assay is sensitive, specific and reproducible.

  19. Composition of Anopheles mosquitoes, their blood-meal hosts, and Plasmodium falciparum infection rates in three islands with disparate bed net coverage in Lake Victoria, Kenya.

    PubMed

    Ogola, Edwin; Villinger, Jandouwe; Mabuka, Danspaid; Omondi, David; Orindi, Benedict; Mutunga, James; Owino, Vincent; Masiga, Daniel K

    2017-09-08

    Small islands serve as potential malaria reservoirs through which new infections might come to the mainland and may be important targets in malaria elimination efforts. This study investigated malaria vector species diversity, blood-meal hosts, Plasmodium infection rates, and long-lasting insecticidal net (LLIN) coverage on Mageta, Magare and Ngodhe Islands of Lake Victoria in western Kenya, a region where extensive vector control is implemented on the mainland. From trapping for six consecutive nights per month (November 2012 to March 2015) using CDC light traps, pyrethrum spray catches and backpack aspiration, 1868 Anopheles mosquitoes were collected. Based on their cytochrome oxidase I (COI) and intergenic spacer region PCR and sequencing, Anopheles gambiae s.l. (68.52%), Anopheles coustani (19.81%) and Anopheles funestus s.l. (11.67%) mosquitoes were differentiated. The mean abundance of Anopheles mosquitoes per building per trap was significantly higher (p < 0.001) in Mageta than in Magare and Ngodhe. Mageta was also the most populated island (n = 6487) with low LLIN coverage of 62.35% compared to Ngodhe (n = 484; 88.31%) and Magare (n = 250; 98.59%). Overall, 416 (22.27%) engorged Anopheles mosquitoes were analysed, of which 41 tested positive for Plasmodium falciparum infection by high-resolution melting (HRM) analysis of 18S rRNA and cytochrome b PCR products. Plasmodium falciparum infection rates were 10.00, 11.76, 0, and 18.75% among blood-fed An. gambiae s.s. (n = 320), Anopheles arabiensis (n = 51), An. funestus s.s. (n = 29), and An. coustani (n = 16), respectively. Based on HRM analysis of vertebrate cytochrome b, 16S rRNA and COI PCR products, humans (72.36%) were the prominent blood-meal hosts of malaria vectors, but 20.91% of blood-meals were from non-human vertebrate hosts. These findings demonstrate high Plasmodium infection rates among the primary malaria vectors An. gambiae s.s. and An. arabiensis, as well as in An. coustani

  20. Plasmodium falciparum infection in febrile Congolese children: prevalence of clinical malaria 10 years after introduction of artemisinin-combination therapies.

    PubMed

    Etoka-Beka, Mandingha Kosso; Ntoumi, Francine; Kombo, Michael; Deibert, Julia; Poulain, Pierre; Vouvoungui, Christevy; Kobawila, Simon Charles; Koukouikila-Koussounda, Felix

    2016-12-01

    To investigate the proportion of malaria infection in febrile children consulting a paediatric hospital in Brazzaville, to determine the prevalence of submicroscopic malaria infection, to characterise Plasmodium falciparum infection and compare the prevalence of uncomplicated P. falciparum malaria according to haemoglobin profiles. Blood samples were collected from children aged <10 years with an axillary temperature ≥37.5 °C consulting the paediatric ward of Marien Ngouabi Hospital in Brazzaville. Parasite density was determined and all samples were screened for P. falciparum by nested polymerase chain reaction (PCR) using the P. falciparum msp-2 marker to detect submicroscopic infections and characterise P. falciparum infection. Sickle cell trait was screened by PCR. A total of 229 children with fever were recruited, of whom 10% were diagnosed with uncomplicated malaria and 21% with submicroscopic infection. The mean parasite density in children with uncomplicated malaria was 42 824 parasites/μl of blood. The multiplicity of infection (MOI) was 1.59 in children with uncomplicated malaria and 1.69 in children with submicroscopic infection. The mean haemoglobin level was 10.1 ± 1.7 for children with uncomplicated malaria and 12.0 ± 8.6 for children with submicroscopic infection. About 13% of the children harboured the sickle cell trait (HbAS); the rest had normal haemoglobin (HbAA). No difference in prevalence of uncomplicated malaria and submicroscopic infection, parasite density, haemoglobin level, MOI and P. falciparum genetic diversity was observed according to haemoglobin type. The low prevalence of uncomplicated malaria in febrile Congolese children indicates the necessity to investigate carefully other causes of fever. © 2016 John Wiley & Sons Ltd.

  1. Cytokine-associated neutrophil extracellular traps and antinuclear antibodies in Plasmodium falciparum infected children under six years of age

    PubMed Central

    Baker, Virginia S; Imade, Godwin E; Molta, Norman B; Tawde, Pallavi; Pam, Sunday D; Obadofin, Michael O; Sagay, Soloman A; Egah, Daniel Z; Iya, Daniel; Afolabi, Bangmboye B; Baker, Murray; Ford, Karen; Ford, Robert; Roux, Kenneth H; Keller, Thomas CS

    2008-01-01

    Background In Plasmodium falciparum-infected children, the relationships between blood cell histopathology, blood plasma components, development of immunocompetence and disease severity remain poorly understood. Blood from Nigerian children with uncomplicated malaria was analysed to gain insight into these relationships. This investigation presents evidence for circulating neutrophil extracellular traps (NETs) and antinuclear IgG antibodies (ANA). The presence of NETs and ANA to double-stranded DNA along with the cytokine profiles found suggests autoimmune mechanisms that could produce pathogenesis in children, but immunoprotection in adults. Methods Peripheral blood smear slides and blood samples obtained from 21 Nigerian children under six years of age, presenting with uncomplicated malaria before and seven days after initiation of sulphadoxine-pyrimethamine (SP) treatment were analysed. The slides were stained with Giemsa and with DAPI. Levels of the pro-inflammatory cytokines IFN-γ, IL-2, TNF, CRP, and IL-6, select anti-inflammatory cytokines TGF-β and IL-10, and ANA were determined by immunoassay. Results The children exhibited circulating NETs with adherent parasites and erythrocytes, elevated ANA levels, a Th2 dominated cytokine profile, and left-shifted leukocyte differential counts. Nonspecific ANA levels were significant in 86% of the children pretreatment and in 100% of the children seven days after SP treatment, but in only 33% of age-matched control samples collected during the season of low parasite transmission. Levels of ANA specific for dsDNA were significant in 81% of the children both pre-treatment and post treatment. Conclusion The results of this investigation suggest that NET formation and ANA to dsDNA may induce pathology in falciparum-infected children, but activate a protective mechanism against falciparum malaria in adults. The significance of in vivo circulating chromatin in NETs and dsDNA ANA as a causative factor in the

  2. Effect of Eurycoma longifolia extract on the Glutathione level in Plasmodium falciparum infected erythrocytes in vitro.

    PubMed

    Mohd Ridzuan, M A R; Noor Rain, A; Zhari, I; Zakiah, I

    2005-12-01

    In the present study we examined the effect of E. longifolia methanol extract (TA164) on the GSH levels of P. falciparum infected erythrocytes and uninfected erythrocytes. Our study on parasite growth shows the IC50 and IC75 values of TA164 to be 0.17 g/ml and 6 g/ml respectively while for BSO was 25.5 g/ml and 46.5 g/ml respectively. About 95% to 100% growth inhibition of P. falciparum infected erythrocyte was observed when treated with TA164 and BSO at 16 g/ml and 64 g/ml respectively. The study on GSH contents indicated that non-infected erythrocytes treated with 6 g/ml (IC75 values) of TA164 at 24 hours incubation showed less GSH content as compared to non-treated erythrocytes. A similar observation was seen on treated trophozoite infected erythrocyte (10% parasitemia) when treated with 6 g/ml at 3 hours incubation. Analysis of the GSH contents of parasite compartments treated with TA164 at the same concentration (6 g/ml) for 3 hours incubation indicated a reduction of GSH contents. At the same concentration, TA164 did not affect the GSH contents of enriched trophozoite infected erythrocytes (60-70% parasitemia). TA164 did affect the GSH content of non-infected erythrocyte at 24 hours (accept IC50 value) as well as the parasite compartments (trophozoite infected erythrocyte and parasite itself) but fails to affect the GSH content of enriched trophozoite infected erythrocyte.

  3. A lysine-rich membrane-associated PHISTb protein involved in alteration of the cytoadhesive properties of Plasmodium falciparum-infected red blood cells.

    PubMed

    Proellocks, Nicholas I; Herrmann, Susann; Buckingham, Donna W; Hanssen, Eric; Hodges, Emma K; Elsworth, Brendan; Morahan, Belinda J; Coppel, Ross L; Cooke, Brian M

    2014-07-01

    The genomes of malaria parasites (Plasmodium spp.) contain a family of genes encoding proteins with a Plasmodium helical interspersed subtelomeric (PHIST) domain, most of which are predicted to be exported into the parasite-infected human red blood cell (iRBC). Here, using transgenic parasites and a combination of cellular, biochemical, and biophysical assays, we have characterized and determined the function of a novel member of the PHIST protein family in Plasmodium falciparum, termed lysine-rich membrane-associated PHISTb (LyMP). LyMP was shown to associate directly with the cytoskeleton of iRBCs where it plays a role in their abnormal ability to adhere to a protein expressed on vascular endothelial cells, resulting in sequestration. Deletion of LyMP dramatically reduced adhesion of iRBCs to CD36 by 55%, which was completely restored to wild-type levels on complementation. Intriguingly, in the absence of LyMP, formation of RBC membrane knobs and the level of surface exposure of the parasites' major cytoadhesive ligand, PfEMP1, were identical to those for the parental parasite line, demonstrating for the first time an additional mechanism that enhances cytoadherence of iRBCs beyond those already recognized. Our findings identify LyMP as a previously unknown RBC cytoskeletal-binding protein that is likely to be of major significance in the complex pathophysiology of falciparum malaria.-Proellocks, N. I., Herrmann, S., Buckingham, D. W., Hanssen, E., Hodges, E. K., Elsworth, B., Morahan, B. J., Coppel, R. L., Cooke, B. M. A lysine-rich membrane-associated PHISTb protein involved in alteration of the cytoadhesive properties of Plasmodium falciparum infected red blood cells.

  4. 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.

  5. Hemoglobin S and C affect protein export in Plasmodium falciparum-infected erythrocytes

    PubMed Central

    Kilian, Nicole; Srismith, Sirikamol; Dittmer, Martin; Ouermi, Djeneba; Bisseye, Cyrille; Simpore, Jacques; Cyrklaff, Marek; Sanchez, Cecilia P.; Lanzer, Michael

    2015-01-01

    ABSTRACT Malaria is a potentially deadly disease. However, not every infected person develops severe symptoms. Some people are protected by naturally occurring mechanisms that frequently involve inheritable modifications in their hemoglobin. The best studied protective hemoglobins are the sickle cell hemoglobin (HbS) and hemoglobin C (HbC) which both result from a single amino acid substitution in β-globin: glutamic acid at position 6 is replaced by valine or lysine, respectively. How these hemoglobinopathies protect from severe malaria is only partly understood. Models currently proposed in the literature include reduced disease-mediating cytoadherence of parasitized hemoglobinopathic erythrocytes, impaired intraerythrocytic development of the parasite, dampened inflammatory responses, or a combination thereof. Using a conditional protein export system and tightly synchronized Plasmodium falciparum cultures, we now show that export of parasite-encoded proteins across the parasitophorous vacuolar membrane is delayed, slower, and reduced in amount in hemoglobinopathic erythrocytes as compared to parasitized wild type red blood cells. Impaired protein export affects proteins targeted to the host cell cytoplasm, Maurer's clefts, and the host cell plasma membrane. Impaired protein export into the host cell compartment provides a mechanistic explanation for the reduced cytoadherence phenotype associated with parasitized hemoglobinopathic erythrocytes. PMID:25701664

  6. 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

  7. Subclinical Plasmodium falciparum infections act as year-round reservoir for malaria in the hypoendemic Chittagong Hill districts of Bangladesh.

    PubMed

    Shannon, Kerry L; Khan, Wasif A; Sack, David A; Alam, M Shafiul; Ahmed, Sabeena; Prue, Chai Shwai; Khyang, Jacob; Ram, Malathi; Haq, M Zahirul; Akter, Jasmin; Glass, Gregory E; Shields, Timothy M; Galagan, Sean R; Nyunt, Myaing M; Sullivan, David J

    2016-08-01

    An analysis of the risk factors and seasonal and spatial distribution of individuals with subclinical malaria in hypoendemic Bangladesh was performed. From 2009 to 2012, active malaria surveillance without regard to symptoms was conducted on a random sample (n=3971) and pregnant women (n=589) during a cohort malaria study in a population of 24000. The overall subclinical Plasmodium falciparum malaria point prevalence was 1.0% (n=35), but was 3.2% (n=18) for pregnant women. The estimated incidence was 39.9 per 1000 person-years for the overall population. Unlike symptomatic malaria, with a marked seasonal pattern, subclinical infections did not show a seasonal increase during the rainy season. Sixty-nine percent of those with subclinical P. falciparum infections reported symptoms commonly associated with malaria compared to 18% without infection. Males, pregnant women, jhum cultivators, and those living closer to forests and at higher elevations had a higher prevalence of subclinical infection. Hypoendemic subclinical malaria infections were associated with a number of household and demographic factors, similar to symptomatic cases. Unlike clinical symptomatic malaria, which is highly seasonal, these actively detected infections were present year-round, made up the vast majority of infections at any given time, and likely acted as reservoirs for continued transmission. Copyright © 2016 The Authors. Published by Elsevier Ltd.. All rights reserved.

  8. Antibody recognition of Plasmodium falciparum infected red blood cells by symptomatic and asymptomatic individuals in the Brazilian Amazon.

    PubMed

    Fratus, Alessandra Sampaio Bassi; Cabral, Fernanda Janku; Fotoran, Wesley Luzetti; Medeiros, Márcia Melo; Carlos, Bianca Cechetto; Martha, Rosimeire dalla; da Silva, Luiz Hildebrando Pereira; Lopes, Stefanie Costa Pinto; Costa, Fabio Trindade Maranhão; Wunderlich, Gerhard

    2014-08-01

    In the Amazon Region, there is a virtual absence of severe malaria and few fatal cases of naturally occurring Plasmodium falciparum infections; this presents an intriguing and underexplored area of research. In addition to the rapid access of infected persons to effective treatment, one cause of this phenomenon might be the recognition of cytoadherent variant proteins on the infected red blood cell (IRBC) surface, including the var gene encoded P. falciparum erythrocyte membrane protein 1. In order to establish a link between cytoadherence, IRBC surface antibody recognition and the presence or absence of malaria symptoms, we phenotype-selected four Amazonian P. falciparum isolates and the laboratory strain 3D7 for their cytoadherence to CD36 and ICAM1 expressed on CHO cells. We then mapped the dominantly expressed var transcripts and tested whether antibodies from symptomatic or asymptomatic infections showed a differential recognition of the IRBC surface. As controls, the 3D7 lineages expressing severe disease-associated phenotypes were used. We showed that there was no profound difference between the frequency and intensity of antibody recognition of the IRBC-exposed P. falciparum proteins in symptomatic vs. asymptomatic infections. The 3D7 lineages, which expressed severe malaria-associated phenotypes, were strongly recognised by most, but not all plasmas, meaning that the recognition of these phenotypes is frequent in asymptomatic carriers, but is not necessarily a prerequisite to staying free of symptoms.

  9. Antibody recognition of Plasmodium falciparum infected red blood cells by symptomatic and asymptomatic individuals in the Brazilian Amazon

    PubMed Central

    Fratus, Alessandra Sampaio Bassi; Cabral, Fernanda Janku; Fotoran, Wesley Luzetti; Medeiros, Márcia Melo; Carlos, Bianca Cechetto; Martha, Rosimeire dalla; da Silva, Luiz Hildebrando Pereira; Lopes, Stefanie Costa Pinto; Costa, Fabio Trindade Maranhão; Wunderlich, Gerhard

    2014-01-01

    In the Amazon Region, there is a virtual absence of severe malaria and few fatal cases of naturally occurring Plasmodium falciparum infections; this presents an intriguing and underexplored area of research. In addition to the rapid access of infected persons to effective treatment, one cause of this phenomenon might be the recognition of cytoadherent variant proteins on the infected red blood cell (IRBC) surface, including the var gene encoded P. falciparum erythrocyte membrane protein 1. In order to establish a link between cytoadherence, IRBC surface antibody recognition and the presence or absence of malaria symptoms, we phenotype-selected four Amazonian P. falciparum isolates and the laboratory strain 3D7 for their cytoadherence to CD36 and ICAM1 expressed on CHO cells. We then mapped the dominantly expressed var transcripts and tested whether antibodies from symptomatic or asymptomatic infections showed a differential recognition of the IRBC surface. As controls, the 3D7 lineages expressing severe disease-associated phenotypes were used. We showed that there was no profound difference between the frequency and intensity of antibody recognition of the IRBC-exposed P. falciparum proteins in symptomatic vs. asymptomatic infections. The 3D7 lineages, which expressed severe malaria-associated phenotypes, were strongly recognised by most, but not all plasmas, meaning that the recognition of these phenotypes is frequent in asymptomatic carriers, but is not necessarily a prerequisite to staying free of symptoms. PMID:25099336

  10. High-throughput screening platform identifies small molecules that prevent sequestration of Plasmodium falciparum-infected erythrocytes.

    PubMed

    Gullingsrud, Justin; Milman, Neta; Saveria, Tracy; Chesnokov, Olga; Williamson, Kathryn; Srivastava, Anand; Gamain, Benoit; Duffy, Patrick E; Oleinikov, Andrew V

    2015-04-01

    We developed a 2-step approach to screen molecules that prevent and/or reverse Plasmodium falciparum-infected erythrocyte (IE) binding to host receptors. IE adhesion and sequestration in vasculature causes severe malaria, and therefore antiadhesion therapy might be useful as adjunctive treatment. IE adhesion is mediated by the polymorphic family (approximately 60 members) of P. falciparum EMP1 (PfEMP1) multidomain proteins. We constructed sets of PfEMP1 domains that bind ICAM-1, CSA, or CD36, receptors that commonly support IE binding. Combinations of domain-coated beads were assayed by Bio-Plex technology as a high-throughput molecular platform to screen antiadhesion molecules (antibodies and small molecules). Molecules identified as so-called hits in the screen (first step) then could be assayed individually for inhibition of binding of live IE to receptors (second step). In proof-of-principle studies, the antiadhesion activity of several antibodies was concordant in Bio-Plex and live IE assays. Using this 2-step approach, we identified several molecules in a small molecule library of 10 000 compounds that could inhibit and reverse binding of IEs to ICAM-1 and CSA receptors. This 2-step screening approach should be efficient for identification of antiadhesion drug candidates for falciparum malaria. Published by Oxford University Press on behalf of the Infectious Diseases Society of America 2014. This work is written by (a) US Government employee(s) and is in the public domain in the US.

  11. Secretion of a malarial histidine-rich protein (Pf HRP II) from Plasmodium falciparum-infected erythrocytes

    SciTech Connect

    Howard, R.J.; Uni, S.; Aikawa, M.; Aley, S.B.; Leech, J.H.; Lew, A.M.; Wellems, T.E.; Rener, J.; Taylor, D.W.

    1986-10-01

    Plasmodium falciparum-infected erythrocytes (IRBCs) synthesis several histidine-rich proteins (HRPs) that accumulate high levels of (/sup 3/H)histidine but very low levels of amino acids such as (/sup 3/H)isoleucine or (/sup 35/S)methionine. The authors prepared a monoclonal antibody which reacts specifically with one of these HRPs (Pf HRP II) and studied the location and synthesis of this protein during the parasite's intracellular growth. With the knob-positive Malayan Camp strain of P. falciparum, the monoclonal antibody identified a multiplet of protein of protein bands with major species at M/sub r/ 72,000 and 69,000. Pf HRP II synthesis began with immature parasites (rings) and continued through the trophozoite stage. The M/sub r/ 72,000 band of Pf HRP II, but not the faster moving bands of the multiplet, was recovered as a water-soluble protein from the culture supernatant of intact IRBCs. Approximately 50% of the total (/sup 3/H)histidine radioactivity incorporated into the M/sub r/ 72,000 band was extracellular between 2 and 24 h of culture. Immunofluorescence and cryothin-section immunoelectron microscopy localized Pf HRP II to several cell compartments including the parasite cytoplasm, as concentrated packets in the host erythrocyte cytoplasm and at the IRBC membrane. The results provide evidence for an intracellular route of transport for a secreted malarial protein from the parasite through several membranes and the host cell cytoplasm.

  12. 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.

  13. 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

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

    PubMed

    Perdijk, Olaf; Arama, Charles; Giusti, Pablo; Maiga, Bakary; Troye-Blomberg, Marita; Dolo, Amagana; Doumbo, Ogobara; Persson, Jan-Olov; Boström, Stéphanie

    2013-11-25

    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. 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. 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 Hb:Hp2-2 complexes showed

  15. 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

  16. Spatial mapping and prediction of Plasmodium falciparum infection risk among school-aged children in Côte d'Ivoire.

    PubMed

    Houngbedji, Clarisse A; Chammartin, Frédérique; Yapi, Richard B; Hürlimann, Eveline; N'Dri, Prisca B; Silué, Kigbafori D; Soro, Gotianwa; Koudou, Benjamin G; Assi, Serge-Brice; N'Goran, Eliézer K; Fantodji, Agathe; Utzinger, Jürg; Vounatsou, Penelope; Raso, Giovanna

    2016-09-07

    In Côte d'Ivoire, malaria remains a major public health issue, and thus a priority to be tackled. The aim of this study was to identify spatially explicit indicators of Plasmodium falciparum infection among school-aged children and to undertake a model-based spatial prediction of P. falciparum infection risk using environmental predictors. A cross-sectional survey was conducted, including parasitological examinations and interviews with more than 5,000 children from 93 schools across Côte d'Ivoire. A finger-prick blood sample was obtained from each child to determine Plasmodium species-specific infection and parasitaemia using Giemsa-stained thick and thin blood films. Household socioeconomic status was assessed through asset ownership and household characteristics. Children were interviewed for preventive measures against malaria. Environmental data were gathered from satellite images and digitized maps. A Bayesian geostatistical stochastic search variable selection procedure was employed to identify factors related to P. falciparum infection risk. Bayesian geostatistical logistic regression models were used to map the spatial distribution of P. falciparum infection and to predict the infection prevalence at non-sampled locations via Bayesian kriging. Complete data sets were available from 5,322 children aged 5-16 years across Côte d'Ivoire. P. falciparum was the predominant species (94.5 %). The Bayesian geostatistical variable selection procedure identified land cover and socioeconomic status as important predictors for infection risk with P. falciparum. Model-based prediction identified high P. falciparum infection risk in the north, central-east, south-east, west and south-west of Côte d'Ivoire. Low-risk areas were found in the south-eastern area close to Abidjan and the south-central and west-central part of the country. The P. falciparum infection risk and related uncertainty estimates for school-aged children in Côte d'Ivoire represent the most up

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

    USDA-ARS?s Scientific Manuscript database

    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...

  18. Abnormal PfEMP1/knob display on Plasmodium falciparum-infected erythrocytes containing hemoglobin variants: fresh insights into malaria pathogenesis and protection

    PubMed Central

    Fairhurst, Rick M.; Bess, Cameron D.; Krause, Michael A.

    2012-01-01

    Hemoglobin (Hb) variants are associated with reduced risk of life-threatening Plasmodium falciparum malaria syndromes, including cerebral malaria and severe malarial anemia. Despite decades of research, the mechanisms by which common Hb variants – sickle HbS, HbC, α-thalassemia, fetal HbF – protect African children against severe and fatal malaria have not been fully elucidated. In vitro experimental and epidemiological data have long suggested that Hb variants do not confer malaria protection by restricting the growth of parasites in red blood cells (RBCs). Recently, four Hb variants were found to impair cytoadherence, the binding of P. falciparum-infected RBCs (PfRBCs) to microvascular endothelial cells (MVECs), a centrally important event in both parasite survival and malaria pathogenesis in humans. Impaired cytoadherence is associated with abnormal display of P. falciparum erythrocyte membrane protein 1 (PfEMP1), the parasite’s major cytoadherence ligand and virulence factor, on the surface of host RBCs. We propose a model in which Hb variants allow parasites to display relatively low levels of PfEMP1, sufficient for sequestering PfRBCs in microvessels and avoiding their clearance from the bloodstream by the spleen. By preventing the display of high levels of PfEMP1, Hb variants may weaken the binding of PfRBCs to MVECs, compromising their ability to activate endothelium and initiate the downstream microvascular events that drive the pathogenesis of malaria. PMID:22634344

  19. α-Thalassemia Impairs the Cytoadherence of Plasmodium falciparum-Infected Erythrocytes

    PubMed Central

    Krause, Michael A.; Diakite, Seidina A. S.; Lopera-Mesa, Tatiana M.; Amaratunga, Chanaki; Arie, Takayuki; Traore, Karim; Doumbia, Saibou; Konate, Drissa; Keefer, Jeffrey R.; Diakite, Mahamadou; Fairhurst, Rick M.

    2012-01-01

    Background α-thalassemia results from decreased production of α-globin chains that make up part of hemoglobin tetramers (Hb; α2β2) and affects up to 50% of individuals in some regions of sub-Saharan Africa. Heterozygous (−α/αα) and homozygous (−α/−α) genotypes are associated with reduced risk of severe Plasmodium falciparum malaria, but the mechanism of this protection remains obscure. We hypothesized that α-thalassemia impairs the adherence of parasitized red blood cells (RBCs) to microvascular endothelial cells (MVECs) and monocytes – two interactions that are centrally involved in the pathogenesis of severe disease. Methods and Findings We obtained P. falciparum isolates directly from Malian children with malaria and used them to infect αα/αα (normal), −α/αα and −α/−α RBCs. We also used laboratory-adapted P. falciparum clones to infect −/−α RBCs obtained from patients with HbH disease. Following a single cycle of parasite invasion and maturation to the trophozoite stage, we tested the ability of parasitized RBCs to bind MVECs and monocytes. Compared to parasitized αα/αα RBCs, we found that parasitized −α/αα, −α/−α and −/−α RBCs showed, respectively, 22%, 43% and 63% reductions in binding to MVECs and 13%, 33% and 63% reductions in binding to monocytes. α-thalassemia was associated with abnormal display of P. falciparum erythrocyte membrane protein 1 (PfEMP1), the parasite’s main cytoadherence ligand and virulence factor, on the surface of parasitized RBCs. Conclusions Parasitized α-thalassemic RBCs show PfEMP1 display abnormalities that are reminiscent of those on the surface of parasitized sickle HbS and HbC RBCs. Our data suggest a model of malaria protection in which α-thalassemia ameliorates the pro-inflammatory effects of cytoadherence. Our findings also raise the possibility that other unstable hemoglobins such as HbE and unpaired α-globin chains (in the case of β-thalassemia) protect against

  20. The Complexity of Plasmodium Falciparum Infections in Children in Western Kenya

    DTIC Science & Technology

    2006-01-01

    fuse and form short-lived diploid zygotes. These undergo meiotic division, creating haploid cells that after further development and asexual...the common feature of being single copy in the haploid blood stages of the parasite life cycle and having highly variable regions with insertion...and evolution of the malaria vaccine candidate merozoite surface protein-1 (MSP-1) of Plasmodium falciparum. Gene 304: 65-75. 44. Ferreira MU, Liu

  1. 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.

  2. Malaria's Missing Number: Calculating the Human Component of R0 by a Within-Host Mechanistic Model of Plasmodium falciparum Infection and Transmission

    PubMed Central

    Johnston, Geoffrey L.; Smith, David L.; Fidock, David A.

    2013-01-01

    Human infection by malarial parasites of the genus Plasmodium begins with the bite of an infected Anopheles mosquito. Current estimates place malaria mortality at over 650,000 individuals each year, mostly in African children. Efforts to reduce disease burden can benefit from the development of mathematical models of disease transmission. To date, however, comprehensive modeling of the parameters defining human infectivity to mosquitoes has remained elusive. Here, we describe a mechanistic within-host model of Plasmodium falciparum infection in humans and pathogen transmission to the mosquito vector. Our model incorporates the entire parasite lifecycle, including the intra-erythrocytic asexual forms responsible for disease, the onset of symptoms, the development and maturation of intra-erythrocytic gametocytes that are transmissible to Anopheles mosquitoes, and human-to-mosquito infectivity. These model components were parameterized from malaria therapy data and other studies to simulate individual infections, and the ensemble of outputs was found to reproduce the full range of patient responses to infection. Using this model, we assessed human infectivity over the course of untreated infections and examined the effects in relation to transmission intensity, expressed by the basic reproduction number R0 (defined as the number of secondary cases produced by a single typical infection in a completely susceptible population). Our studies predict that net human-to-mosquito infectivity from a single non-immune individual is on average equal to 32 fully infectious days. This estimate of mean infectivity is equivalent to calculating the human component of malarial R0. We also predict that mean daily infectivity exceeds five percent for approximately 138 days. The mechanistic framework described herein, made available as stand-alone software, will enable investigators to conduct detailed studies into theories of malaria control, including the effects of drug treatment and

  3. 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

  4. Chloroquine uptake by Plasmodium falciparum-infected human erythrocytes during in vitro culture and its relationship to chloroquine resistance.

    PubMed Central

    Verdier, F; Le Bras, J; Clavier, F; Hatin, I; Blayo, M C

    1985-01-01

    Chloroquine uptake by Plasmodium falciparum-infected human erythrocytes (RBC) was studied in vitro before and during culture by measuring the chloroquine gradient between the cells and medium (C/M) by high-pressure liquid chromatography. The C/M values were 5.9 +/- 2.7 (n = 23) for uninfected RBC, 13 to 34 for six chloroquine-susceptible isolates (concentration required to inhibit 50% of parasite growth, less than 100 nmol/liter) in partially infected RBC (parasitemia from 0.3 to 5%) (n = 28), and 8.4 to 4.9 for four chloroquine-resistant isolates (concentration required to inhibit 50% of parasite growth, 320 to 1,500 nmol/liter) in partially infected RBC (parasitemia from 0.4 to 5%) (n = 26). Two isolates were studied before and after adaptation to continuous culture. C/M was found to decrease (34.2 to 2.1 and 19.3 to 4.9), whereas the concentration required to inhibit 50% of parasite growth increased (35 to 1,400 and 54 to 1,500 nmol/liter), thus indicating the acquisition of chloroquine resistance. These results demonstrate that chloroquine uptake decreased in RBC in which the infective strain, initially susceptible, became resistant in culture and imply that the drug is bound to ferriprotoporphyrin IX to a lesser extent or that a parasite protein competes with ferriprotoporphyrin IX to a greater extent. We suggest that genotypic modifications in the mechanism of chloroquine uptake might occur in the parasite. PMID:3890728

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

    PubMed

    Gnémé, Awa; Guelbéogo, Wamdaogo M; Riehle, Michelle M; Sanou, Antoine; Traoré, Alphonse; Zongo, Soumanaba; Eiglmeier, Karin; Kabré, Gustave B; Sagnon, N'Falé; Vernick, Kenneth D

    2013-06-14

    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. 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. 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. 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, and could lead to false-positive results

  6. 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

  7. Efficacy of chloroquine in the treatment of uncomplicated Plasmodium falciparum infection in East Timor, 2000.

    PubMed

    Ezard, Nadine; Burns, Matthew; Lynch, Caroline; Cheng, Qin; Edstein, Michael D

    2003-09-01

    Access to an efficacious antimalarial drug is one of the cornerstones of the Roll Back Malaria initiative to decrease malaria morbidity and mortality. This is particularly important in emergency and post-emergency settings where access to treatment in the event of therapeutic failure may be restricted. In the aftermath of violence securing the independence of East Timor (1999), chloroquine continued to be used as first line therapy for the treatment of malaria. However, reliable data on the efficacy of chloroquine was not available. This paper represents the first attempt to document treatment failure with chloroquine in East Timor. The study was conducted using modified WHO guidelines in a rural hospital outpatient department in an area where there is seasonal transmission of both Plasmodium vivax and Plasmodium falciparum. 48 subjects presenting with fever and microscopically confirmed P. falciparum monoinfection were given supervised oral treatment with quality controlled chloroquine (25 mg/kg over 3 days) and followed clinically and parasitologically for 28 days. 32 of the 48 subjects had recurrent parasitaemia, and PCR confirmed that 28 of these were likely to be due to recrudescent parasites. The corrected treatment failure was, therefore, 58.3% (28/48), with all but one (2.1%) defined as late treatment failures (7-28 days after treatment). Further research into appropriate chemotherapy, including sulphadoxine-pyrimethamine and combination therapy for example with artemesinin or its derivatives, should be undertaken to select the most appropriate first line therapy for the management of uncomplicated malaria in East Timor.

  8. Odours of Plasmodium falciparum-infected participants influence mosquito-host interactions.

    PubMed

    de Boer, Jetske G; Robinson, Ailie; Powers, Stephen J; Burgers, Saskia L G E; Caulfield, John C; Birkett, Michael A; Smallegange, Renate C; van Genderen, Perry J J; Bousema, Teun; Sauerwein, Robert W; Pickett, John A; Takken, Willem; Logan, James G

    2017-08-24

    Malaria parasites are thought to influence mosquito attraction to human hosts, a phenomenon that may enhance parasite transmission. This is likely mediated by alterations in host odour because of its importance in mosquito host-searching behaviour. Here, we report that the human skin odour profile is affected by malaria infection. We compared the chemical composition and attractiveness to Anopheles coluzzii mosquitoes of skin odours from participants that were infected by Controlled Human Malaria Infection with Plasmodium falciparum. Skin odour composition differed between parasitologically negative and positive samples, with positive samples collected on average two days after parasites emerged from the liver into the blood, being associated with low densities of asexual parasites and the absence of gametocytes. We found a significant reduction in mosquito attraction to skin odour during infection for one experiment, but not in a second experiment, possibly due to differences in parasite strain. However, it does raise the possibility that infection can affect mosquito behaviour. Indeed, several volatile compounds were identified that can influence mosquito behaviour, including 2- and 3-methylbutanal, 3-hydroxy-2-butanone, and 6-methyl-5-hepten-2-one. To better understand the impact of our findings on Plasmodium transmission, controlled studies are needed in participants with gametocytes and higher parasite densities.

  9. Midgut Microbiota of the Malaria Mosquito Vector Anopheles gambiae and Interactions with Plasmodium falciparum Infection

    PubMed Central

    Boissière, Anne; Tchioffo, Majoline T.; Bachar, Dipankar; Abate, Luc; Marie, Alexandra; Nsango, Sandrine E.; Shahbazkia, Hamid R.; Awono-Ambene, Parfait H.; Levashina, Elena A.; Christen, Richard; Morlais, Isabelle

    2012-01-01

    The susceptibility of Anopheles mosquitoes to Plasmodium infections relies on complex interactions between the insect vector and the malaria parasite. A number of studies have shown that the mosquito innate immune responses play an important role in controlling the malaria infection and that the strength of parasite clearance is under genetic control, but little is known about the influence of environmental factors on the transmission success. We present here evidence that the composition of the vector gut microbiota is one of the major components that determine the outcome of mosquito infections. A. gambiae mosquitoes collected in natural breeding sites from Cameroon were experimentally challenged with a wild P. falciparum isolate, and their gut bacterial content was submitted for pyrosequencing analysis. The meta-taxogenomic approach revealed a broader richness of the midgut bacterial flora than previously described. Unexpectedly, the majority of bacterial species were found in only a small proportion of mosquitoes, and only 20 genera were shared by 80% of individuals. We show that observed differences in gut bacterial flora of adult mosquitoes is a result of breeding in distinct sites, suggesting that the native aquatic source where larvae were grown determines the composition of the midgut microbiota. Importantly, the abundance of Enterobacteriaceae in the mosquito midgut correlates significantly with the Plasmodium infection status. This striking relationship highlights the role of natural gut environment in parasite transmission. Deciphering microbe-pathogen interactions offers new perspectives to control disease transmission. PMID:22693451

  10. Biophysical Properties of Plasmodium falciparum-Infected Erythrocytes from Novel Analysis of the Flicker Phenomena

    NASA Astrophysics Data System (ADS)

    Arie, Takayuki; Jin, Albert; Dvorak, James

    2002-03-01

    Infectious processes often modulate the intrinsic properties of vertebrate cells. We studied the modulation of human erythrocyte flicker during the intra-erythrocytic cycle of Plasmodium falciparum malaria using video microscopy imaging and a data analysis system of our design to extract flicker spectra and lateral cell edge undulations of individual erythrocytes at various stages of infection. The total flicker power, the power weighted mean flicker frequency, the mode amplitudes of lateral undulations, and the time correlation of translation mode was quantified by infectious stage and modeled theoretically. Our results suggest that malaria-infected erythrocytes become increasingly more rigid following infection and provide an insight into the modulation of erythrocyte cytoplasmic viscosity by the parasites. These studies of malaria-infected erythrocytes elucidate the kinetics of both membrane and cellular changes that are relevant to blood microcirculation and improve our understanding of the malaria disease process.

  11. Initiation of gametocytogenesis at very low parasite density in Plasmodium falciparum infection

    PubMed Central

    Farid, Ryan; Dixon, Matthew W.; Tilley, Leann

    2017-01-01

    Abstract The recent focus on the elimination of malaria has led to an increased interest in the role of sexual stages in its transmission. We introduce Plasmodium falciparum gametocyte exported protein-5 (PfGEXP5) transcript analysis as an important tool for evaluating the earliest (ring) stage sexual gametocytes in the blood of infected individuals. We show that gametocyte rings are detected in the peripheral blood immediately following establishment of asexual infections—without the need for triggers such as high-density asexual parasitemia or drug treatment. Committed gametocytes are refractory to the commonly used drug piperaquine, and mature gametocytes reappear in the bloodstream 10 days after the initial appearance of gametocyte rings. A further wave of commitment is observed following recrudescent asexual parasitemia, and these gametocytes are again refractory to piperaquine treatment. This work has implications for monitoring gametocyte and transmission dynamics and responses to drug treatment. PMID:28498997

  12. Nosocomial Plasmodium falciparum infections confirmed by molecular typing in Medellín, Colombia

    PubMed Central

    González, Lina; Ochoa, Jesus; Franco, Liliana; Arroyave, Marta; Restrepo, Eliana; Blair, Silvia; Maestre, Amanda

    2005-01-01

    Three cases of nosocomial malaria are reported from patients of the Internal Medicine Ward of a tertiary University teaching hospital in Medellin, Colombia. Epidemiological research, based on entomological captures, medical records review and interviews of nursery staff about patient care practices potentially involving contact with blood, were carried out. Molecular characterization of Plasmodium falciparum was based on the amplification of MSP1, MSP2 and GLURP genes. This method enabled confirmation of the same P. falciparum genotype in all three patients as well as in a fourth one (index case). The presence of nosocomial malaria was confirmed and it was concluded that the most likely source of transmission was through multi-dose preparations of heparin applied to heparin locks. PMID:15703072

  13. 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.

  14. ParaSight-F rapid manual diagnostic test of Plasmodium falciparum infection.

    PubMed Central

    Uguen, C.; Rabodonirina, M.; De Pina, J. J.; Vigier, J. P.; Martet, G.; Maret, M.; Peyron, F.

    1995-01-01

    The ParaSight(R)-F test is a qualitative diagnostic test of Plasmodium falciparum, which is based on the detection by a monoclonal antibody of a species-specific soluble antigen (histidine-rich protein (HRP-II)) in whole blood and which can be performed without special equipment. A visual reading is given by a polyclonal antibody coupled with dye-loaded liposomes; when positive, a pink line appears. The test has been compared with microscopic examination of thin blood smears and with Quantitative Buffy Coat malaria test (QBC(R) in a single-blind study. A total of 358 patients who had returned to France from malarial areas and consulted their doctor with symptoms or for a routine examination were enrolled in the study; 33 of them were found to have a falciparum malaria infection by the diagnostic test. On the day of consultation, the specificity of the ParaSight(R)-F test was 99% and its sensitivity 94%. The follow-up of infected patients after treatment showed that the test became negative later than the other reference tests. There was no correlation between antigen persistence and the intensity of the ParaSight(R)-F signal or circulating parasitaemia. No cross-reaction was noted for seven malaria cases due to other Plasmodium species. The test was performed quickly (10 tests in 20 minutes), was easy to read, and required minimal space. For cases of imported malaria, the test's specificity and low threshold for detection could make it a valuable adjunct test. However, in its present form, it cannot replace microscopic techniques which are species-specific and quantitative. In endemic areas, the test seems to be very promising by its results and ease of use according to published field studies. Images Fig. 1 Fig. 2 PMID:8846490

  15. Peripheral Blood Stem Cell Transplant Related Plasmodium falciparum Infection in a Patient with Sickle Cell Disease

    PubMed Central

    Mejia, Rojelio; Booth, Garrett S.; Fedorko, Daniel P.; Hsieh, Matthew M.; Khuu, Hanh M.; Klein, Harvey G.; Mu, Jianbing; Fahle, Gary; Nutman, Thomas B.; Su, Xin-Zhuan; Williams, Esther C.; Flegel, Willy A.; Klion, Amy

    2012-01-01

    Background Although transmission of Plasmodium falciparum (Pf) infection during red blood cell transfusion from an infected donor has been well documented, malaria parasites are not known to infect hematopoietic stem cells. We report a case of Pf infection in a patient 11 days after peripheral blood stem cell transplant for sickle cell disease. Study Design and Methods Malaria parasites were detected in thick blood smears by Giemsa staining. Pf HRP2 antigen was measured by ELISA on whole blood and plasma. Pf DNA was detected in whole blood and stem cell retention samples by real-time PCR using Pf species–specific primers and probes. Genotyping of 8 Pf microsatellites was performed on genomic DNA extracted from whole blood. Results Pf was not detected by molecular, serologic or parasitologic means in samples from the recipient until day 11 post-transplant, coincident with the onset of symptoms. In contrast, Pf antigen was retrospectively detected in stored plasma collected 3 months prior to transplant from the asymptomatic donor. Pf DNA was detected in whole blood from both the donor and recipient post-transplant, and genotyping confirmed shared markers between donor and recipient Pf strains. Look back analysis of red blood cell donors was negative for Pf infection. Conclusions These findings are consistent with transmission by the stem cell product and have profound implications with respect to the screening of potential stem cell donors and recipients from malaria-endemic regions. PMID:22536941

  16. 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.

  17. Host vascular endothelial growth factor is trophic for Plasmodium falciparum-infected red blood cells.

    PubMed

    Sachanonta, Navakanit; Medana, Isabelle M; Roberts, Rachel; Jones, Margaret; Day, Nicholas P J; White, Nicholas J; Ferguson, David J P; Turner, Gareth D H; Pongponratn, Emsri

    2008-03-01

    Plasmodium falciparum, the protozoan parasite responsible for severe malaria infection, undergoes a complex life cycle. Infected red blood cells (iRBC) sequester in host cerebral microvessels, which underlies the pathology of cerebral malaria. Using immunohistochemistry on post mortem brain samples, we demonstrated positive staining for vascular endothelial growth factor (VEGF) on iRBC. Confocal microscopy of cultured iRBC revealed accumulation of VEGF within the parasitophorous vacuole, expression of host VEGF-receptor 1 and activated VEGF-receptor 2 on the surface of iRBC, but no accumulation of VEGF receptors within the iRBC. Addition of VEGF to parasite cultures had a trophic effect on parasite growth and also partially rescued growth of drug treated parasites. Both these effects were abrogated when parasites were grown in serum-free medium, suggesting a requirement for soluble VEGF receptor. We conclude that P. falciparum iRBC can bind host VEGF-R on the erythrocyte membrane and accumulate host VEGF within the parasitophorous vacuole, which may have a trophic effect on parasite growth.

  18. 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

  19. The rapid manual ParaSight-F test. A new diagnostic tool for Plasmodium falciparum infection.

    PubMed

    Shiff, C J; Premji, Z; Minjas, J N

    1993-01-01

    A rapid manual test for Plasmodium falciparum, the ParaSight-F test, has been used on a series of patients in a holoendemic malaria area of coastal Tanzania. The test, which is an antigen capture test detecting trophozoite-derived histidine rich protein-II, is simple to perform and provides a definitive answer in about 10 min. It requires no special equipment and is read using a single drop of blood. When compared with 272 thick blood films examined microscopically by 2 observers and confirmed by the QBC malaria test, the ParaSight-F test had 88.9% sensitivity and 87.5% specificity. Detectable antigenaemia in a group of 40 people declined following treatment with Fansidar and by 10 d after treatment all but 4 individuals were antigen free. The remaining 4, although clear of peripheral parasitaemia, remained antigenaemic for 14 d. The test shows great promise for rapid effective diagnosis of P. falciparum in clinics and village health centres where there is no facility for microscopy. Because of its accuracy and rapid action it may even obviate the need for microscopical examination of blood films to diagnose P. falciparum malaria.

  20. VALIDATION OF MICROSATELLITE MARKERS FOR USE IN GENOTYPING POLYCLONAL PLASMODIUM FALCIPARUM INFECTIONS

    PubMed Central

    GREENHOUSE, BRYAN; MYRICK, ALISSA; DOKOMAJILAR, CHRISTIAN; WOO, JONATHAN M.; CARLSON, ELAINE J.; ROSENTHAL, PHILIP J.; DORSEY, GRANT

    2006-01-01

    Genotyping methods for Plasmodium falciparum drug efficacy trials have not been standardized and may fail to accurately distinguish recrudescence from new infection, especially in high transmission areas where polyclonal infections are common. We developed a simple method for genotyping using previously identified microsatellites and capillary electrophoresis, validated this method using mixtures of laboratory clones, and applied the method to field samples. Two microsatellite markers produced accurate results for single-clone but not polyclonal samples. Four other microsatellite markers were as sensitive as, and more specific than, commonly used genotyping techniques based on merozoite surface proteins 1 and 2. When applied to samples from 15 patients in Burkina Faso with recurrent parasitemia after treatment with sulphadoxine-pyrimethamine, the addition of these four microsatellite markers to msp1 and msp2 genotyping resulted in a reclassification of outcomes that strengthened the association between dhfr 59R, an anti-folate resistance mutation, and recrudescence (P = 0.31 versus P = 0.03). Four microsatellite markers performed well on polyclonal samples and may provide a valuable addition to genotyping for clinical drug efficacy studies in high transmission areas. PMID:17123974

  1. Detection of a substantial number of sub-microscopic Plasmodium falciparum infections by polymerase chain reaction: a potential threat to malaria control and diagnosis in Ethiopia

    PubMed Central

    2013-01-01

    Background Prompt and effective malaria diagnosis not only alleviates individual suffering, but also decreases malaria transmission at the community level. The commonly used diagnostic methods, microscopy and rapid diagnostic tests, are usually insensitive at very low-density parasitaemia. Molecular techniques, on the other hand, allow the detection of low-level, sub-microscopic parasitaemia. This study aimed to explore the presence of sub-microscopic Plasmodium falciparum infections using polymerase chain reaction (PCR). The PCR-based parasite prevalence was compared against microscopy and rapid diagnostic test (RDT). Methods This study used 1,453 blood samples collected from clinical patients and sub-clinical subjects to determine the prevalence of sub-microscopic P. falciparum carriages. Subsets of RDT and microscopy negative blood samples were tested by PCR while all RDT and microscopically confirmed P. falciparum-infected samples were subjected to PCR. Finger-prick blood samples spotted on filter paper were used for parasite genomic DNA extraction. Results The prevalence of sub-microscopic P. falciparum carriage was 19.2% (77/400) (95% CI = 15. 4–23.1). Microscopy-based prevalence of P. falciparum infection was 3.7% (54/1,453) while the prevalence was 6.9% (100/1,453) using RDT alone. Using microscopy and PCR, the estimated parasite prevalence was 20.6% if PCR were performed in 1,453 blood samples. The prevalence was estimated to be 22.7% if RDT and PCR were used. Of 54 microscopically confirmed P. falciparum-infected subjects, PCR detected 90.7% (49/54). Out of 100 RDT-confirmed P. falciparum infections; PCR detected 80.0% (80/100). The sensitivity of PCR relative to microscopy and RDT was, therefore, 90.7% and 80%, respectively. The sensitivity of microscopy and RDT relative to PCR was 16.5 (49/299) and 24.2% (80/330), respectively. The overall PCR-based prevalence of P. falciparum infection was 5.6- and 3.3 fold higher than that determined by

  2. Asymptomatic Plasmodium falciparum infection in children is associated with increased auto-antibody production, high IL-10 plasma levels and antibodies to merozoite surface protein 3.

    PubMed

    Guiyedi, Vincent; Bécavin, Christophe; Herbert, Fabien; Gray, Julian; Cazenave, Pierre-André; Kombila, Maryvonne; Crisanti, Andrea; Fesel, Constantin; Pied, Sylviane

    2015-04-16

    Mechanisms of acquired protection to malaria in asymptomatic Plasmodium falciparum carriers are only partially understood. Among them, the role plays by the self-reactive antibodies has not been clarified yet. In this study, the relationship between repertoires of circulating self-reactive and parasite-specific immunoglobulin G (IgG), their correlation with cytokine levels, and their association with protection against malaria was investigated in asymptomatic Plasmodium falciparum-infected Gabonese children. The diversity of P. falciparum-specific antibody repertoire was analysed using a protein micro-array immunoassay, the total auto-antibody repertoire by quantitative immunoblotting and circulating cytokine levels were measured by ELISA in endemic controls (EC) and P. falciparum-infected children from Gabon with asymptomatic (AM) or mild malaria (MM). The association of self- and parasite-specific antibody repertoires with circulating cytokines was evaluated using single linkage hierarchical clustering, Kruskal-Wallis tests and Spearman's rank correlation. Children with AM exhibited an IgG response to merozoite surface protein 3 (MSP3) but not to MSP1-19, although their levels of total P. falciparum-specific IgG were similar to those in the MM group. Moreover, the asymptomatic children had increased levels of autoantibodies recognising brain antigens. In addition, a correlation between IL-10 levels and parasite load was found in AM and MM children. These two groups also exhibited significant correlations between plasma levels of IL-10 and IFN-γ with age and with total plasma IgG levels. IL-10 and IFN-γ levels were also associated with auto-antibody responses in AM. Altogether, these results indicate that a self-reactive polyclonal response associated with increased IgG to MSP3 and high plasma levels of IL-10 and IFN-γ may contribute to protective immune mechanisms triggered in asymptomatic P. falciparum infection in Gabonese children.

  3. 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

  4. 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

  5. High-resolution X-ray imaging of Plasmodium falciparum-infected red blood cells.

    PubMed

    Williams, Garth J; Hanssen, Eric; Peele, Andrew G; Pfeifer, Mark A; Clark, Jesse; Abbey, Brian; Cadenazzi, Guido; de Jonge, Martin D; Vogt, Stefan; Tilley, Leann; Nugent, Keith A

    2008-10-01

    Methods for imaging cellular architecture and ultimately macromolecular complexes and individual proteins, within a cellular environment, are an important goal for cell and molecular biology. Coherent diffractive imaging (CDI) is a method of lensless imaging that can be applied to any individual finite object. A diffraction pattern from a single biological structure is recorded and an iterative Fourier transform between real space and reciprocal space is used to reconstruct information about the architecture of the sample to high resolution. As a test system for cellular imaging, we have applied CDI to an important human pathogen, the malaria parasite, Plasmodium falciparum. We have employed a novel CDI approach, known as Fresnel CDI, which uses illumination with a curved incident wavefront, to image red blood cells infected with malaria parasites. We have examined the intrinsic X-ray absorption contrast of these cells and compared them with cells contrasted with heavy metal stains or immunogold labeling. We compare CDI images with data obtained from the same cells using scanning electron microscopy, light microscopy, and scanning X-ray fluorescence microscopy. We show that CDI can offer new information both within and at the surface of complex biological specimens at a spatial resolution of better than 40 nm. and we demonstrate an imaging modality that conveniently combines scanning X-ray fluorescence microscopy with CDI. The data provide independent confirmation of the validity of the coherent diffractive image and demonstrate that CDI offers the potential to become an important and reliable new high-resolution imaging modality for cell biology. CDI can detect features at high resolution within unsectioned cells.

  6. Associations between Season and Gametocyte Dynamics in Chronic Plasmodium falciparum Infections

    PubMed Central

    Gadalla, Amal A. H.; Schneider, Petra; Churcher, Thomas S.; Nassir, Elkhansaa; Abdel-Muhsin, Abdel-Muhsin A.; Ranford-Cartwright, Lisa C.; Reece, Sarah E.; Babiker, Hamza A.

    2016-01-01

    Introduction In a markedly seasonal malaria setting, the transition from the transmission-free dry season to the transmission season depends on the resurgence of the mosquito population following the start of annual rains. The sudden onset of malaria outbreaks at the start of the transmission season suggests that parasites persist during the dry season and respond to either the reappearance of vectors, or correlated events, by increasing the production of transmission stages. Here, we investigate whether Plasmodium falciparum gametocyte density and the correlation between gametocyte density and parasite density show seasonal variation in chronic (largely asymptomatic) carriers in eastern Sudan. Materials and Methods We recruited and treated 123 malaria patients in the transmission season 2001. We then followed them monthly during four distinct consecutive epidemiological seasons: transmission season 1, transmission-free season, pre-clinical period, and transmission season 2. In samples collected from 25 participants who fulfilled the selection criteria of the current analysis, we used quantitative PCR (qPCR) and RT-qPCR to quantify parasite and gametocyte densities, respectively. Results and Discussion We observed a significant increase in gametocyte density and a significantly steeper positive correlation between gametocyte density and total parasite density during the pre-clinical period compared to the preceding transmission-free season. However, there was no corresponding increase in the density or prevalence of total parasites or gametocyte prevalence. The increase in gametocyte production during the pre-clinical period supports the hypothesis that P. falciparum may respond to environmental cues, such as mosquito biting, to modulate its transmission strategy. Thus, seasonal changes may be important to ignite transmission in unstable-malaria settings. PMID:27870874

  7. A Field-Tailored Reverse Transcription Loop-Mediated Isothermal Assay for High Sensitivity Detection of Plasmodium falciparum Infections.

    PubMed

    Kemleu, Sylvie; Guelig, Dylan; Eboumbou Moukoko, Carole; Essangui, Estelle; Diesburg, Steven; Mouliom, Abas; Melingui, Bernard; Manga, Jeanne; Donkeu, Christiane; Epote, Annie; Texier, Gaëtan; LaBarre, Paul; Burton, Robert; Ayong, Lawrence

    2016-01-01

    Highly sensitive and field deployable molecular diagnostic tools are critically needed for detecting submicroscopic, yet transmissible levels of malaria parasites prevalent in malaria endemic countries worldwide. A reverse transcription loop-mediated isothermal amplification (RT-LAMP) assay was developed and evaluated in comparison with thick blood smear microscopy, an antigen-based rapid diagnostic test (RDT), and an in-house RT-PCR targeting the same RT-LAMP transcript. The optimized assay detected Plasmodium falciparum infections in as little as 0.25ng of total parasite RNA, and exhibited a detection limit of 0.08 parasites/ μL when tested directly on infected whole blood lysates, or ~0.0008 parasites/ μL when using RNA extracts. Assay positivity was observed as early as eight minutes from initiation of the RT-LAMP and in most cases the reaction was complete before twenty minutes. Clinical evaluation of the assay on 132 suspected malaria cases resulted in a positivity rate of 90% for RT-LAMP using extracted RNA, and 85% when using whole blood lysates. The positivity rates were 70% for P. falciparum-specific RDT, 83% for RT-PCR, and 74% for thick blood smear microscopy (Mean parasite density = 36,986 parasites/ μL). Concordance rates between the developed RT-LAMP and comparator tests were greater than 75%, the lowest being with light microscopy (78%, McNemar's test: P = 0.0002), and the highest was with RT-PCR (87%, McNemar's test: P = 0.0523). Compared to reference RT-PCR, assay sensitivity was 90% for RT-LAMP on whole blood, and 96% for RT-LAMP using corresponding RNA extracts. Electricity-free heaters were further developed and evaluated in comparison with a battery-operated isothermal amplification machine for use with the developed test in resource-limited settings. Taken together, the data highlight the benefits of targeting high abundant RNA transcripts in molecular diagnosis, as well as the potential usefulness of the developed RT-LAMP-assay in malaria

  8. A Field-Tailored Reverse Transcription Loop-Mediated Isothermal Assay for High Sensitivity Detection of Plasmodium falciparum Infections

    PubMed Central

    Kemleu, Sylvie; Guelig, Dylan; Eboumbou Moukoko, Carole; Essangui, Estelle; Diesburg, Steven; Mouliom, Abas; Melingui, Bernard; Manga, Jeanne; Donkeu, Christiane; Epote, Annie; Texier, Gaëtan; LaBarre, Paul; Burton, Robert

    2016-01-01

    Highly sensitive and field deployable molecular diagnostic tools are critically needed for detecting submicroscopic, yet transmissible levels of malaria parasites prevalent in malaria endemic countries worldwide. A reverse transcription loop-mediated isothermal amplification (RT-LAMP) assay was developed and evaluated in comparison with thick blood smear microscopy, an antigen-based rapid diagnostic test (RDT), and an in-house RT-PCR targeting the same RT-LAMP transcript. The optimized assay detected Plasmodium falciparum infections in as little as 0.25ng of total parasite RNA, and exhibited a detection limit of 0.08 parasites/ μL when tested directly on infected whole blood lysates, or ~0.0008 parasites/ μL when using RNA extracts. Assay positivity was observed as early as eight minutes from initiation of the RT-LAMP and in most cases the reaction was complete before twenty minutes. Clinical evaluation of the assay on 132 suspected malaria cases resulted in a positivity rate of 90% for RT-LAMP using extracted RNA, and 85% when using whole blood lysates. The positivity rates were 70% for P. falciparum-specific RDT, 83% for RT-PCR, and 74% for thick blood smear microscopy (Mean parasite density = 36,986 parasites/ μL). Concordance rates between the developed RT-LAMP and comparator tests were greater than 75%, the lowest being with light microscopy (78%, McNemar’s test: P = 0.0002), and the highest was with RT-PCR (87%, McNemar’s test: P = 0.0523). Compared to reference RT-PCR, assay sensitivity was 90% for RT-LAMP on whole blood, and 96% for RT-LAMP using corresponding RNA extracts. Electricity-free heaters were further developed and evaluated in comparison with a battery-operated isothermal amplification machine for use with the developed test in resource-limited settings. Taken together, the data highlight the benefits of targeting high abundant RNA transcripts in molecular diagnosis, as well as the potential usefulness of the developed RT-LAMP-assay in

  9. Absence of an Association Between Plasmodium falciparum Infection and Post-Ivermectin Loa-Related Non-Neurologic Serious Adverse Events

    PubMed Central

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

    2014-01-01

    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

  10. Efficacy of herbal remedies used by herbalists in Oyo State Nigeria for treatment of Plasmodium falciparum infections--a survey and an observation.

    PubMed

    Ajaiyeoba, E O; Falade, C O; Fawole, O I; Akinboye, D O; Gbotosho, G O; Bolaji, O M; Ashidi, J S; Abiodun, O O; Osowole, O S; Itiola, O A; Oladepo, O; Sowunmi, A; Oduola, A M J

    2004-06-01

    In the course of evaluating the contribution of phytomedicine to possible drug discovery of antimalarial drugs, an ethnomedical survey of specialized children traditional clinics was done. In the observational multi center study, efficacy of eight different herbal remedies, each consisting of 3-8 ingredients and administered by herbalists were investigated in clients enrolled in the six traditional clinics in Oyo (urban center) and Otu (rural center) of Oyo State, Nigeria. The clients, aged between six months and fifteen years with clinical symptoms of malaria were enrolled in the clinics of the herbalists, as their usual practice. Oral informed consents were obtained from their parents or guardians. Microscopic diagnosis of malaria infection was used to evaluate parasitaemia and validate efficacy of herbal remedies. Results of the analysis showed that, of the 163 clients of the herbalists, only 62 (30 from Oyo, 32 from Otu) had microscopically confirmed P. falciparum infection. Only results from 54 clients (29/30 (Oyo) and 25/32 (Otu) with P. falciparum infection could be evaluated. Plasmodium falciparum infection in 88% (23/29) of clients from Oyo responded to treatment with the herbal remedies while cure rate in clients from Otu was 42% (13/25). Parasite densities ranged from 171 to 53,613 parasites/microl blood and 87 to 36,209 parasites/microl blood in patients from Oyo and Otu respectively. The herbalists administered the remedies and Gossypium arboreum, Anarcadium occidentalis, Citrus medica, Phyllanthus amarus and Lippia multiflora were the main ingredients in the efficacious remedies. The herbalists gave detailed descriptions of each of the 8 herbal remedies proffered. The results confirm the efficacy of two of the eight herbal remedies, thereby validating the role of ethnomedicine as a possible source for the discovery of new chemotherapeutic agents in the treatment of P. falciparum malaria.

  11. Morbidity and mortality associated with Plasmodium vivax and Plasmodium falciparum infection in a tertiary care kidney hospital.

    PubMed

    Imtiaz, Salman; Drohlia, Murtaza F; Nasir, Kiran; Hussain, Mehwish; Ahmad, Aasim

    2015-11-01

    Malaria is a disease of tropical regions and both types of plasmodia, i.e. Plasmodium falciparum and Plasmodium vivax, cause significant morbidity and mortality. P. vivax was thought to be benign and cause less morbidity and mortality. Many reports showed the devastating effect of vivax malaria too. We compared the clinical symptoms, laboratory markers, treatment and outcome of both the plasmodia. This is a retrospective analysis of 95 patients admitted to The Kidney Center, Karachi in a duration of 15 years (1997-2012); 45 patients with falciparum malaria and 50 patients with vivax malaria, and compared the clinical presentation, laboratory workup, treatment and outcome in both groups. The two groups constitute a mixed population of diabetes, chronic kidney disease (CKD) and hemodialysis patients. Both plasmodia have an equal clinical impact in terms of fever and rigors, anorexia, nausea, feeling of dyspnea, change in the mental status, changes in the urine color, diarrhea, volume depletion and pedal edema. However, patients with falciparum had significantly more vomiting (P = 0.02), oliguria (P = 0.003) and jaundice (P = 0.003). Laboratory parameters also showed a severe impact of falciparum, as there was more severe anemia and kidney and liver dysfunction. More patients were treated with dialysis and blood transfusion in the falciparum group. The outcome in the two groups was not significantly different in terms of death and days of hospitalization. Falciparum malaria has a higher clinical impact than the vivax malaria, but vivax is not as benign as it was once thought to be. It also has devastating effects on vulnerable populations like patients with CKD and diabetes.

  12. Fcgamma receptor IIa (CD32) polymorphism is associated with protection of infants against high-density Plasmodium falciparum infection. VII. Asembo Bay Cohort Project.

    PubMed

    Shi, Y P; Nahlen, B L; Kariuki, S; Urdahl, K B; McElroy, P D; Roberts, J M; Lal, A A

    2001-07-01

    In vitro studies have shown that inhibition of Plasmodium falciparum blood-stage parasite growth by antibody-dependent cellular inhibition is mediated by cooperation between malaria-specific IgG1 and IgG3, but not IgG2, and monocytes via the Fcgamma receptor II (FcgammaRII). A single amino acid substitution at position 131 in FcgammaRIIa is critical in the binding of human IgG subclasses. The hypothesis that the FcgammaRIIa-Arg/Arg131 genotype, which does not bind to IgG2, is a host genetic factor for protection against high-density P. falciparum infection was tested. One hundred eighty-two infants from a large community-based birth cohort study in western Kenya were selected for an unmatched case-control study. Results showed that the infants with the FcgammaRIIa-Arg/Arg131 genotype were significantly less likely to be at risk for high-density falciparum infection, compared with infants with the FcgammaRIIa-His/Arg131 genotype (adjusted odds ratio, 0.278; 95% confidence interval, 0.123-0.627; P=.0021). This finding supports the hypothesis.

  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. Stage-dependent fate of Plasmodium falciparum-infected red blood cells in the spleen and sickle-cell trait-related protection against malaria.

    PubMed

    Diakité, Seidina A S; Ndour, Papa Alioune; Brousse, Valentine; Gay, Frederick; Roussel, Camille; Biligui, Sylvestre; Dussiot, Michaël; Prendki, Virginie; Lopera-Mesa, Tatiana M; Traoré, Karim; Konaté, Drissa; Doumbia, Saibou; Cros, Jérôme; Dokmak, Safi; Fairhurst, Rick M; Diakité, Mahamadou; Buffet, Pierre A

    2016-09-21

    Sickle-cell trait (HbAS) reduces falciparum malaria risk and suppresses parasitaemia. Although several candidate mechanisms have been proposed, their epidemiological, clinical and experimental correlates have not been adequately explained. To explore the basis for generally lower parasitaemias and delayed malaria episodes in children with HbAS, it is hypothesized here that their spleen-dependent removal of ring-infected red blood cells (RBCs) is more efficient than in children with normal haemoglobin A (HbAA). The mechanical splenic retention of Plasmodium falciparum-infected RBCs from subjects with HbAS or HbAA was investigated using two physiologically relevant methods: microsphiltration and ex vivo spleen perfusion. P. falciparum-infected RBCs obtained from in vitro cultures and from patients were used in either normoxic or hypoxic conditions. The effect of sickling in ring-infected HbAS RBCs was also investigated. When a laboratory-adapted parasite strain was analysed, ring-infected HbAA RBCs were retained in microsphilters at similar or greater levels than ring-infected HbAS RBCs, under normoxic (retention rate 62.5 vs 43.8 %, P < 0.01) and hypoxic (54.0 vs 38.0 %, P = 0.11) conditions. When parasitized RBCs from Malian children were analysed, retention of ring-infected HbAA and HbAS RBCs was similar when tested either directly ex vivo (32.1 vs 28.7 %, P = 0.52) or after one re-invasion in vitro (55.9 vs 43.7 %, P = 0.30). In hypoxia, sickling of uninfected and ring-infected HbAS RBCs (8.6 vs 5.7 %, P = 0.51), and retention of ring-infected HbAA and HbAS RBCs in microsphilters (72.5 vs 68.8 %, P = 0.38) and spleens (41.2 vs 30.4 %, P = 0.11), also did not differ. Retention of HbAS and HbAA RBCs infected with mature P. falciparum stages was greater than 95 %. Sickle-cell trait is not associated with higher retention or sickling of ring-infected RBCs in experimental systems reflecting the mechanical sensing of RBCs by the human spleen. As

  15. Transgenic mosquitoes expressing a phospholipase A(2) gene have a fitness advantage when fed Plasmodium falciparum-infected blood.

    PubMed

    Smith, Ryan C; Kizito, Christopher; Rasgon, Jason L; Jacobs-Lorena, Marcelo

    2013-01-01

    Genetically modified mosquitoes have been proposed as an alternative strategy to reduce the heavy burden of malaria. In recent years, several proof-of-principle experiments have been performed that validate the idea that mosquitoes can be genetically modified to become refractory to malaria parasite development. We have created two transgenic lines of Anophelesstephensi, a natural vector of Plasmodium falciparum, which constitutively secrete a catalytically inactive phospholipase A2 (mPLA2) into the midgut lumen to interfere with Plasmodium ookinete invasion. Our experiments show that both transgenic lines expressing mPLA2 significantly impair the development of rodent malaria parasites, but only one line impairs the development of human malaria parasites. In addition, when fed on malaria-infected blood, mosquitoes from both transgenic lines are more fecund than non-transgenic mosquitoes. Consistent with these observations, cage experiments with mixed populations of transgenic and non-transgenic mosquitoes show that the percentage of transgenic mosquitoes increases when maintained on Plasmodium-infected blood. Our results suggest that the expression of an anti-Plasmodium effector gene gives transgenic mosquitoes a fitness advantage when fed malaria-infected blood. These findings have important implications for future applications of transgenic mosquito technology in malaria control.

  16. Transgenic Mosquitoes Expressing a Phospholipase A2 Gene Have a Fitness Advantage When Fed Plasmodium falciparum-Infected Blood

    PubMed Central

    Smith, Ryan C.; Kizito, Christopher; Rasgon, Jason L.; Jacobs-Lorena, Marcelo

    2013-01-01

    Background Genetically modified mosquitoes have been proposed as an alternative strategy to reduce the heavy burden of malaria. In recent years, several proof-of-principle experiments have been performed that validate the idea that mosquitoes can be genetically modified to become refractory to malaria parasite development. Results We have created two transgenic lines of Anophelesstephensi, a natural vector of Plasmodium falciparum, which constitutively secrete a catalytically inactive phospholipase A2 (mPLA2) into the midgut lumen to interfere with Plasmodium ookinete invasion. Our experiments show that both transgenic lines expressing mPLA2 significantly impair the development of rodent malaria parasites, but only one line impairs the development of human malaria parasites. In addition, when fed on malaria-infected blood, mosquitoes from both transgenic lines are more fecund than non-transgenic mosquitoes. Consistent with these observations, cage experiments with mixed populations of transgenic and non-transgenic mosquitoes show that the percentage of transgenic mosquitoes increases when maintained on Plasmodium-infected blood. Conclusions Our results suggest that the expression of an anti-Plasmodium effector gene gives transgenic mosquitoes a fitness advantage when fed malaria-infected blood. These findings have important implications for future applications of transgenic mosquito technology in malaria control. PMID:24098427

  17. Human T-Cell Lymphotropic Virus Type 1 Gag Indeterminate Western Blot Patterns in Central Africa: Relationship to Plasmodium falciparum Infection

    PubMed Central

    Mahieux, Renaud; Horal, Peter; Mauclère, Philippe; Mercereau-Puijalon, Odile; Guillotte, Micheline; Meertens, Laurent; Murphy, Edward; Gessain, Antoine

    2000-01-01

    To gain insight on the significance of human T-cell lymphotropic virus type 1 (HTLV-1) indeterminate serological reactivities, we studied villagers of South Cameroon, focusing on a frequent and specific HTLV-1 Gag indeterminate profile (HGIP) pattern (gag p19, p26, p28, and p30 without p24 or Env gp21 and gp46). Among the 102 sera studied, 29 from all age groups had a stable HGIP pattern over a period of 4 years. There was no epidemiological evidence for sexual or vertical transmission of HGIP. Seventy-five percent of HGIP sera reacted positively on MT2 HTLV-1-infected cells by immunofluorescence assay. However, we could not isolate any HTLV-1 virus or detect the presence of p19 Gag protein in cultures of peripheral blood mononuclear cells obtained from individuals with strong HGIP reactivity. PCR experiments conducted with primers for HTLV-1 and HTLV-2 (HTLV-1/2 primers) encompassing different regions of the virus did not yield HTLV-1/2 proviral sequences from individuals with HGIP. Using 11 peptides corresponding to HTLV-1 or HTLV-2 immunodominant B epitopes in an enzyme-linked immunosorbent assay, one epitope corresponding to the Gag p19 carboxyl terminus was identified in 75% of HGIP sera, while it was recognized by only 41% of confirmed HTLV-1-positive sera. A positive correlation between HTLV-1 optical density values and titers of antibody to Plasmodium falciparum was also demonstrated. Finally, passage of sera through a P. falciparum-infected erythrocyte-coupled column was shown to specifically abrogate HGIP reactivity but not the HTLV-1 pattern, suggesting the existence of cross-reactivity between HTLV-1 Gag proteins and malaria-derived antigens. These data suggest that in Central Africa, this frequent and specific Western blot is not caused by HTLV-1 infection but could instead be associated with P. falciparum infection. PMID:11060067

  18. The T-Cell Inhibitory Molecule Butyrophilin-Like 2 Is Up-regulated in Mild Plasmodium falciparum Infection and Is Protective During Experimental Cerebral Malaria

    PubMed Central

    Subramaniam, Krishanthi S.; Spaulding, Emily; Ivan, Emil; Mutimura, Eugene; Kim, Ryung S.; Liu, Xikui; Dong, Chen; Feintuch, Catherine M.; Zhang, Xingxing; Anastos, Kathryn; Lauvau, Gregoire; Daily, Johanna P.

    2015-01-01

    Plasmodium falciparum infection can result in severe disease that is associated with elevated inflammation and vital organ dysfunction; however, malaria-endemic residents gain protection from lethal outcomes and manifest only mild symptoms during infection. To characterize host responses associated with this more effective antimalarial response, we characterized whole-blood transcriptional profiles in Rwandan adults during a mild malaria episode and compared them with findings from a convalescence sample. We observed transcriptional up-regulation in many pathways, including type I interferon, interferon γ, complement activation, and nitric oxide during malaria infection, which provide benchmarks of mild disease physiology. Transcripts encoding negative regulators of T-cell activation, such as programmed death ligand 1 (PD-L1), programmed death 1 ligand 2 (PD-L2), and the butyrophilin family member butyrophilin-like 2 (BTNL2) were also increased. To support an important functional role for BTNL2 during malaria infection, we studied chimeric mice reconstituted with BTNL2−/− or wild-type hematopoietic cells that were inoculated with Plasmodium berghei ANKA, a murine model of cerebral malaria. We found that BTNL2−/− chimeric mice had a significant decrease in survival compared with wild-type counterparts. Collectively these data characterize the immune responses associated with mild malaria and uncover a novel role for BTNL2 in the host response to malaria. PMID:25883389

  19. The T-Cell Inhibitory Molecule Butyrophilin-Like 2 Is Up-regulated in Mild Plasmodium falciparum Infection and Is Protective During Experimental Cerebral Malaria.

    PubMed

    Subramaniam, Krishanthi S; Spaulding, Emily; Ivan, Emil; Mutimura, Eugene; Kim, Ryung S; Liu, Xikui; Dong, Chen; Feintuch, Catherine M; Zhang, Xingxing; Anastos, Kathryn; Lauvau, Gregoire; Daily, Johanna P

    2015-10-15

    Plasmodium falciparum infection can result in severe disease that is associated with elevated inflammation and vital organ dysfunction; however, malaria-endemic residents gain protection from lethal outcomes and manifest only mild symptoms during infection. To characterize host responses associated with this more effective antimalarial response, we characterized whole-blood transcriptional profiles in Rwandan adults during a mild malaria episode and compared them with findings from a convalescence sample. We observed transcriptional up-regulation in many pathways, including type I interferon, interferon γ, complement activation, and nitric oxide during malaria infection, which provide benchmarks of mild disease physiology. Transcripts encoding negative regulators of T-cell activation, such as programmed death ligand 1 (PD-L1), programmed death 1 ligand 2 (PD-L2), and the butyrophilin family member butyrophilin-like 2 (BTNL2) were also increased. To support an important functional role for BTNL2 during malaria infection, we studied chimeric mice reconstituted with BTNL2(-/-) or wild-type hematopoietic cells that were inoculated with Plasmodium berghei ANKA, a murine model of cerebral malaria. We found that BTNL2(-/-) chimeric mice had a significant decrease in survival compared with wild-type counterparts. Collectively these data characterize the immune responses associated with mild malaria and uncover a novel role for BTNL2 in the host response to malaria.

  20. Asymptomatic Plasmodium falciparum infection is associated with anaemia in pregnancy and can be more cost-effectively detected by rapid diagnostic test than by microscopy in Kinshasa, Democratic Republic of the Congo

    PubMed Central

    2014-01-01

    Background In areas of high malaria transmission, Plasmodium falciparum infection during pregnancy is characterized by malaria-related anaemia, placental malaria and does not always result in clinical symptoms. This situation is associated with poor pregnancy outcomes. The aim of this study was to determine the extent of asymptomatic P. falciparum infection, its relation with anaemia as well as the most cost-effective technique for its diagnosis in healthy pregnant women living in Kinshasa, Democratic Republic of the Congo. Methods In a cross-sectional study design, information on socio-demographic characteristics and cost data were collected in healthy pregnant women attending antenatal care consultations. Plasmodium falciparum infection was diagnosed using rapid diagnostic test (RDT), microscopy and polymerase chain reaction (PCR). Haemoglobin concentration was also determined. Results In total, 332 pregnant women were enrolled. RDT and microscopy data were available for all the blood samples and 166 samples were analysed by PCR. The prevalence of asymptomatic P. falciparum infection using microscopy, RDTs and PCR, were respectively 21.6%, 27.4% and 29.5%. Taking PCR as a reference, RDTs had a sensitivity of 81.6% and a specificity of 94.9% to diagnose asymptomatic P. falciparum infection. The corresponding values for microscopy were 67.3% and 97.4%. The prevalence of anaemia was 61.1% and asymptomatic malaria increased five times the odds (p < 0.001) of having anaemia. RDTs were more cost-effective compared to microscopy. Incremental cost-effectiveness ratio was US$ 63.47 per microscopy adequately diagnosed case. Conclusion These alarming results emphasize the need to actively diagnose and treat asymptomatic malaria infection during all antenatal care visits. Moreover, in DRC, malaria and anaemia control efforts should be strengthened by promoting the use of insecticide-treated nets, intermittent preventive treatment with sulphadoxine-pyrimethamine and iron

  1. Effects of inflammation and Plasmodium falciparum infection on soluble transferrin receptor and plasma ferritin concentration in different age groups: a prospective longitudinal study in Côte d'Ivoire.

    PubMed

    Righetti, Aurélie A; Wegmüller, Rita; Glinz, Dominik; Ouattara, Mamadou; Adiossan, Lukas G; N'Goran, Eliézer K; Utzinger, Jürg; Hurrell, Richard F

    2013-06-01

    Iron deficiency (ID) is a major cause of anemia, along with other nutritional, parasitic, and genetic factors. Accurate biomarkers are needed to estimate the relative contribution of ID to anemia. Soluble transferrin receptor (sTfR) is thought to be unaffected by inflammation. The objectives were to determine the difference in sTfR and plasma ferritin (PF) concentrations among infants (6-23 mo of age), school-age children (6-8 y of age), and women (15-25 y of age) with and without inflammation and with and without Plasmodium falciparum infection and to assess the effect of adjusting sTfR and PF for inflammation or for P. falciparum infection on the estimated prevalence of ID. The data were derived from a 14-mo prospective longitudinal survey on anemia, which was conducted in the Taabo area, south-central Côte d'Ivoire. At baseline, sTfR concentration was significantly higher in infants and school-age children with either inflammation or P. falciparum infection than in control individuals without inflammation or without P. falciparum infection. Individuals with inflammation had significantly higher PF concentrations than did subjects without inflammation. Adjustments in sTfR concentrations for inflammation or P. falciparum infection in infants and school-age children resulted in significantly lower ID prevalence. Adjustment of PF for inflammation and Plasmodium infection resulted in a higher ID prevalence in infants and women. In Ivorian infants and school-age children, ID prevalence was considerably lower after adjustment of sTfR for inflammation. However, as the prevalence estimates for ID differed widely if based on sTfR or PF, caution is still needed when estimating ID prevalence in areas with a high prevalence of inflammation or malaria. This trial was registered at controlled-trials.com as ISRCTN02181959.

  2. 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.

  3. 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

  4. 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.

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

    PubMed Central

    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

    2012-01-01

    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. PMID:22937223

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

    PubMed

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

    2013-05-07

    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.

  7. Skeleton-binding protein 1 functions at the parasitophorous vacuole membrane to traffic PfEMP1 to the Plasmodium falciparum-infected erythrocyte surface.

    PubMed

    Maier, Alexander G; Rug, Melanie; O'Neill, Matthew T; Beeson, James G; Marti, Matthias; Reeder, John; Cowman, Alan F

    2007-02-01

    A key feature of Plasmodium falciparum, the parasite causing the most severe form of malaria in humans, is its ability to export parasite molecules onto the surface of the erythrocyte. The major virulence factor and variant surface protein PfEMP1 (P falciparum erythrocyte membrane protein 1) acts as a ligand to adhere to endothelial receptors avoiding splenic clearance. Because the erythrocyte is devoid of protein transport machinery, the parasite provides infrastructure for trafficking across membranes it traverses. In this study, we show that the P falciparum skeleton-binding protein 1 (PfSBP1) is required for transport of PfEMP1 to the P falciparum-infected erythrocyte surface. We present evidence that PfSBP1 functions at the parasitophorous vacuole membrane to load PfEMP1 into Maurer clefts during formation of these structures. Furthermore, the major reactivity of antibodies from malaria-exposed multigravid women is directed toward PfEMP1 because this is abolished in the absence of PfSBP1.

  8. Real-Time Quantitative Reverse Transcription PCR for Monitoring of Blood-Stage Plasmodium falciparum Infections in Malaria Human Challenge Trials

    PubMed Central

    Murphy, Sean C.; Prentice, Jennifer L.; Williamson, Kathryn; Wallis, Carolyn K.; Fang, Ferric C.; Fried, Michal; Pinzon, Cris; Wang, Ruobing; Talley, Angela K.; Kappe, Stefan H. I.; Duffy, Patrick E.; Cookson, Brad T.

    2012-01-01

    To detect pre-patent parasitemia, we developed a real-time quantitative reverse transcription-polymerase chain reaction (qRT-PCR) for the asexual 18S ribosomal RNA (rRNAs) of Plasmodium falciparum. Total nucleic acids extracted from whole blood were combined with control RNA and tested by qRT-PCR. The assay quantified > 98.7% of parasite-containing samples to ±0.5 log10 parasites/mL of the nominal value without false positives. The analytical sensitivity was ≥ 20 parasites/mL. The coefficient of variation was 0.6% and 1.8% within runs and 1.6% and 4.0% between runs for high and low parasitemia specimens, respectively. Using this assay, we determined that A-type 18S rRNAs are stably expressed at 1×104 copies per ring-stage parasite. When used to monitor experimental P. falciparum infection of human volunteers, the assay detected blood-stage infections 3.7 days earlier on average than thick blood smears. This validated, internally controlled qRT-PCR method also uses a small (50 μL) sample volume requiring minimal pre-analytical handling, making it useful for clinical trials. PMID:22403305

  9. X-Ray Microanalysis Investigation of the Changes in Na, K, and Hemoglobin Concentration in Plasmodium falciparum-Infected Red Blood Cells

    PubMed Central

    Mauritz, Jakob M.A.; Seear, Rachel; Esposito, Alessandro; Kaminski, Clemens F.; Skepper, Jeremy N.; Warley, Alice; Lew, Virgilio L.; Tiffert, Teresa

    2011-01-01

    Plasmodium falciparum is responsible for severe malaria. During the ∼48 h duration of its asexual reproduction cycle in human red blood cells, the parasite causes profound alterations in the homeostasis of the host red cell, with reversal of the normal Na and K gradients across the host cell membrane, and a drastic fall in hemoglobin content. A question critical to our understanding of how the host cell retains its integrity for the duration of the cycle had been previously addressed by modeling the homeostasis of infected cells. The model predicted a critical contribution of excess hemoglobin consumption to cell integrity (the colloidosmotic hypothesis). Here we tested this prediction with the use of electron-probe x-ray microanalysis to measure the stage-related changes in Na, K, and Fe contents in single infected red cells and in uninfected controls. The results document a decrease in Fe signal with increased Na/K ratio. Interpreted in terms of concentrations, the results point to a sustained fall in host cell hemoglobin concentration with parasite maturation, supporting a colloidosmotic role of excess hemoglobin digestion. The results also provide, for the first time to our knowledge, comprehensive maps of the elemental distributions of Na, K, and Fe in falciparum-infected red blood cells. PMID:21402025

  10. HIV-positive nigerian adults harbor significantly higher serum lumefantrine levels than HIV-negative individuals seven days after treatment for Plasmodium falciparum infection.

    PubMed

    Chijioke-Nwauche, Ifeyinwa; van Wyk, Albert; Nwauche, Chijioke; Beshir, Khalid B; Kaur, Harparkash; Sutherland, Colin J

    2013-09-01

    Management of coinfection with malaria and HIV is a major challenge to public health in developing countries, and yet potential drug-drug interactions between antimalarial and antiviral regimens have not been adequately investigated in people with both infections. Each of the constituent components of artemether-lumefantrine, the first-line regimen for malaria treatment in Nigeria, and nevirapine, a major component of highly active antiretroviral therapy, are drugs metabolized by the cytochrome P450 3A4 isoenzyme system, which is also known to be induced by nevirapine. We examined potential interactions between lumefantrine and nevirapine in 68 HIV-positive adults, all of whom were diagnosed with asymptomatic Plasmodium falciparum infections by microscopy. Post hoc PCR analysis confirmed the presence of P. falciparum in only a minority of participants. Day 7 capillary blood levels of lumefantrine were significantly higher in HIV-positive participants than in 99 HIV-negative controls (P = 0.0011). Associations between day 7 levels of lumefantrine and risk of persistent parasitemia could not be evaluated due to inadequate power. Further investigations of the impact of nevirapine on in vivo malaria treatment outcomes in HIV-infected patients are thus needed.

  11. 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.

  12. Plasmodium falciparum-infected red blood cells depend on a functional glutathione de novo synthesis attributable to an enhanced loss of glutathione.

    PubMed Central

    Lüersen, K; Walter, R D; Müller, S

    2000-01-01

    During the erythrocytic cycle, Plasmodium falciparum is highly dependent on an adequate thiol status for its survival. Glutathione reductase as well as de novo synthesis of GSH are responsible for the maintenance of the intracellular GSH level. The first and rate-limiting step of the synthetic pathway is catalysed by gamma-glutamylcysteine synthetase (gamma-GCS). Using L-buthionine-(S, R)-sulphoximine (BSO), a specific inhibitor of the gamma-GCS, we show that the infection with P. falciparum causes drastic changes in the GSH metabolism of red blood cells (RBCs). Infected RBCs lose GSH at a rate 40-fold higher than non-infected RBCs. The de novo synthesis of the tripeptide was found to be essential for parasite survival. GSH depletion by BSO inhibits the development of P. falciparum with an IC(50) of 73 microM. The effect of the drug is abolished by supplementation with GSH or GSH monoethyl ester. Our studies demonstrate that the plasmodicidal effect of the inhibitor BSO does not depend on its specificity towards its target enzyme in the parasite, but on the changed physiological needs for the metabolite GSH in the P. falciparum-infected RBCs. Therefore the depletion of GSH is proposed as a chemotherapeutic strategy for malaria, and gamma-GCS is proposed as a potential drug target. PMID:10677377

  13. 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.

  14. House Structure Is Associated with Plasmodium falciparum Infection in a Low-Transmission Setting in Southern Zambia.

    PubMed

    Ippolito, Matthew M; Searle, Kelly M; Hamapumbu, Harry; Shields, Timothy M; Stevenson, Jennifer C; Thuma, Philip E; Moss, William J; For The Southern Africa International Center Of Excellence For Malaria Research

    2017-08-07

    House structure may influence the risk of malaria by affecting mosquito entry and indoor resting. Identification of construction features associated with protective benefits could inform vector control approaches, even in low-transmission settings. We examined the association between house structure and malaria prevalence in a cross-sectional analysis of 2,788 children and adults residing in 866 houses in a low-transmission area of Southern Province, Zambia, over the period 2008-2012. Houses were categorized according to wall (brick/cement block or mud/grass) and roof (metal or grass) material. Malaria was assessed by point-of-care rapid diagnostic test (RDT) for Plasmodium falciparum. We identified 52 RDT-positive individuals residing in 41 houses, indicating an overall prevalence of parasitemia in the sample of 1.9%, ranging from 1.4% to 8.8% among the different house types. Occupants of higher quality houses had reduced odds of P. falciparum malaria compared with those in the lowest quality houses after controlling for bed net use, indoor insecticide spraying, clustering by house, cohabitation with another RDT-positive individual, ecologic risk defined as nearest distance to a Strahler-classified third-order stream, education, age, and gender (adjusted odds ratio [OR]: 0.26, 95% confidence interval [CI]: 0.09-0.73, P = 0.01 for houses with brick/cement block walls and metal roof; OR: 0.22, 95% CI: 0.09-0.52, P < 0.01 for houses with brick/cement block walls and grass roof). Housing improvements offer a promising approach to vector control in low-transmission settings that circumvents the threat posed by insecticide resistance, and may confer a protective benefit of similar magnitude to current vector control strategies.

  15. Prophylaxis of Plasmodium falciparum Infection in a Human Challenge Model with WR 238605, a New 8-Aminoquinoline Antimalarial

    PubMed Central

    Brueckner, Ralf P.; Coster, Trinka; Wesche, David L.; Shmuklarsky, Moshe; Schuster, Brian G.

    1998-01-01

    The prophylactic efficacy of WR 238605, a primaquine analog, was studied with a human Plasmodium falciparum challenge model. A single oral dose of 600 mg, administered 1 day prior to challenge, successfully protected three of four subjects. The fourth subject developed mild, oligosymptomatic malaria on day 31, with drug concentrations one-half of those in the protected individuals. WR 238605 appears to be a promising prophylactic drug for P. falciparum malaria. PMID:9593172

  16. Plasmodium falciparum infection during dry season: IgG responses to Anopheles gambiae salivary gSG6-P1 peptide as sensitive biomarker for malaria risk in Northern Senegal

    PubMed Central

    2013-01-01

    Background The Northern part of Senegal is characterized by a low and seasonal transmission of malaria. However, some Plasmodium falciparum infections and malaria clinical cases are reported during the dry season. This study aims to assess the relationship between IgG antibody (Ab) responses to gSG6-P1 mosquito salivary peptide and the prevalence of P. falciparum infection in children during the dry season in the Senegal River Valley. The positive association of the Ab response to gSG6-P1, as biomarker of human exposure to Anopheles vector bite, and P. falciparum infectious status (uninfected, infected-asymptomatic or infected-symptomatic) will allow considering this biomarker as a potential indicator of P. falciparum infection risk during the dry season. Methods Microscopic examination of thick blood smears was performed in 371 and 310 children at the start (January) and at the end (June) of the dry season, respectively, in order to assess the prevalence of P. falciparum infection. Collected sera were used to evaluate IgG response to gSG6-P1 by ELISA. Association between parasitological and clinical data (infected-asymptomatic or infected-symptomatic) and the anti-gSG6-P1 IgG levels were evaluated during this period. Results The prevalence of P. falciparum infection was very low to moderate according to the studied period and was higher in January (23.5%) compared to June (3.5%). Specific IgG response was also different between uninfected children and asymptomatic carriers of the parasite. Children with P. falciparum infection in the dry season showed higher IgG Ab levels to gSG6-P1 than uninfected children. Conclusions The results strengthen the hypothesis that malaria transmission is maintained during the dry season in an area of low and seasonal transmission. The measurement of IgG responses to gSG6-P1 salivary peptide could be a pertinent indicator of human malaria reservoir or infection risk in this particular epidemiological context. This promising

  17. 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

  18. A longitudinal study on anaemia in children with Plasmodium falciparum infection in the Mount Cameroon region: prevalence, risk factors and perceptions by caregivers.

    PubMed

    Sumbele, Irene Ule Ngole; Samje, Moses; Nkuo-Akenji, Theresa

    2013-03-05

    In heavily endemic malaria areas, it is almost inevitable that malarial infection will be associated with anaemia, although malaria may not be the prime cause of it. Anaemia is a major public health problem in Cameroon. We hypothesized that, factors other than falciparum malaria account for anaemia in the study area. A longitudinal study was conducted among 351 Plasmodium falciparum positive children to determine the prevalence, risk factors and the perception of anaemia by the caregivers in a semi-rural community. The investigative methods included the use of a structured questionnaire, clinical evaluation and laboratory investigations. At enrolment the overall prevalence of anaemia as assessed by Hb concentration (Hb < 11 g/dl) was 80.3% (282). Following treatment the prevalence of persistent anaemia was 6% and 46.2% of the children achieved haematological recovery by day 42. Exploratory multiple linear regression analysis showed the following; parasitaemia density (P < 0.01), enlarged spleen (P < 0.05), duration of fever > 2 days (P < 0.01), high white blood cell count (P < 0.001), sex (P < 0.05), iron status indicators (ferritin and transferrin) (P < 0.001), level of education of the caregiver (P < 0.05), management of onset of malaria by caregiver (P < 0.005) and wasting (P < 0.05) to be risk factors for anaemia in children with falciparum infection. Approximately 75.5% (265) of the caregivers had some knowledge about anaemia. The identified risk factors revealed the important contributors to the pathogenesis of anaemia in the Mount Cameroon region. Control efforts should therefore be directed towards proper health education emphasizing on proper health seeking behaviour and attitudes of the population.

  19. Antibodies to variant surface antigens of Plasmodium falciparum-infected erythrocytes are associated with protection from treatment failure and the development of anemia in pregnancy.

    PubMed

    Feng, Gaoqian; Aitken, Elizabeth; Yosaatmadja, Francisca; Kalilani, Linda; Meshnick, Steven R; Jaworowski, Anthony; Simpson, Julie A; Rogerson, Stephen J

    2009-07-15

    In pregnancy-associated malaria (PAM), Plasmodium falciparum-infected erythrocytes (IEs) express variant surface antigens (VSA-PAM) that evade existing immunity and mediate placental sequestration. Antibodies to VSA-PAM develop with gravidity and block placental adhesion or opsonize IEs for phagocytic clearance, helping to prevent maternal anemia and low birth weight in infants. Using serum samples from 141 pregnant Malawian women with parasitemia enrolled in a randomized trial of antimalarials and VSA-PAM-expressing CS2 IEs, we quantified levels of immunoglobulin (Ig) G to VSA-PAM by flow cytometry and levels of opsonizing antibodies by measuring uptake of IEs by THP1 promonocytes. After controlling for gravidity and antimalarial treatment, higher levels of IgG to VSA-PAM were associated with decreased anemia at delivery (odds ratio [OR], 0.66 [95% confidence interval {CI}, 0.46-0.93]; P = .018) and were weakly associated with decreased parasitological failure (OR, 0.78 [95% CI, 0.60-1.03]; P = .075), especially reinfection (OR, 0.73 [95% CI, 0.53-1.01]; P = .057). Higher levels of opsonizing antibodies to CS2 IEs were associated with less maternal anemia (OR, 0.31 [95% CI, 0.13-0.74]; P = .008) and treatment failure (OR, 0.48 [95% CI, 0.25-0.90]; P = .023), primarily because of recrudescent infection (OR, 0.49 [95% CI, 0.21-1.12]; P = .089). Higher levels of both IgG antibodies to VSA-PAM and opsonizing antibodies, a functional measure of immunity, correlate with parasite clearance and less anemia in pregnancy malaria.

  20. A longitudinal study on anaemia in children with Plasmodium falciparum infection in the Mount Cameroon region: prevalence, risk factors and perceptions by caregivers

    PubMed Central

    2013-01-01

    Background In heavily endemic malaria areas, it is almost inevitable that malarial infection will be associated with anaemia, although malaria may not be the prime cause of it. Anaemia is a major public health problem in Cameroon. We hypothesized that, factors other than falciparum malaria account for anaemia in the study area. Methods A longitudinal study was conducted among 351 Plasmodium falciparum positive children to determine the prevalence, risk factors and the perception of anaemia by the caregivers in a semi-rural community. The investigative methods included the use of a structured questionnaire, clinical evaluation and laboratory investigations. Results At enrolment the overall prevalence of anaemia as assessed by Hb concentration (Hb < 11 g/dl) was 80.3% (282). Following treatment the prevalence of persistent anaemia was 6% and 46.2% of the children achieved haematological recovery by day 42. Exploratory multiple linear regression analysis showed the following; parasitaemia density (P < 0.01), enlarged spleen (P < 0.05), duration of fever > 2 days (P < 0.01), high white blood cell count (P < 0.001), sex (P < 0.05), iron status indicators (ferritin and transferrin) (P < 0.001), level of education of the caregiver (P < 0.05), management of onset of malaria by caregiver (P < 0.005) and wasting (P < 0.05) to be risk factors for anaemia in children with falciparum infection. Approximately 75.5% (265) of the caregivers had some knowledge about anaemia. Conclusion The identified risk factors revealed the important contributors to the pathogenesis of anaemia in the Mount Cameroon region. Control efforts should therefore be directed towards proper health education emphasizing on proper health seeking behaviour and attitudes of the population. PMID:23497273

  1. An exported kinase (FIKK4.2) that mediates virulence-associated changes in Plasmodium falciparum-infected red blood cells.

    PubMed

    Kats, Lev M; Fernandez, Kate M; Glenister, Fiona K; Herrmann, Susann; Buckingham, Donna W; Siddiqui, Ghizal; Sharma, Laveena; Bamert, Rebecca; Lucet, Isabelle; Guillotte, Micheline; Mercereau-Puijalon, Odile; Cooke, Brian M

    2014-04-01

    Alteration of the adhesive and mechanical properties of red blood cells caused by infection with the malaria parasite Plasmodium falciparum underpin both its survival and extreme pathogenicity. A unique family of parasite putative exported kinases, collectively called FIKK (Phenylalanine (F) - Isoleucine (I) - Lysine (K) - Lysine (K)), has recently been implicated in these pathophysiological processes, however, their precise function in P. falciparum-infected red blood cells or their likely role in malaria pathogenesis remain unknown. Here, for the first time, we demonstrate that one member of the FIKK family, FIKK4.2, can function as an active kinase and is localised in a novel and distinct compartment of the parasite-infected red blood cell which we have called K-dots. Notably, targeted disruption of the gene encoding FIKK4.2 (fikk4.2) dramatically alters the parasite's ability to modify and remodel the red blood cells in which it multiplies. Specifically, red blood cells infected with fikk4.2 knockout parasites were significantly less rigid and less adhesive when compared with red blood cells infected with normal parasites from which the transgenic clones had been derived, despite expressing similar levels of the major cytoadhesion ligand, PfEMP1, on the red blood cell surface. Notably, these changes were accompanied by dramatically altered knob-structures on infected red blood cells that play a key role in cytoadhesion which is responsible for much of the pathogenesis associated with falciparum malaria. Taken together, our data identifies FIKK4.2 as an important kinase in the pathogenesis of P. falciparum malaria and strengthens the attractiveness of FIKK kinases as targets for the development of novel next-generation anti-malaria drugs.

  2. Gravidity-Dependent Production of Antibodies That Inhibit Binding of Plasmodium falciparum-Infected Erythrocytes to Placental Chondroitin Sulfate Proteoglycan during Pregnancy

    PubMed Central

    O'Neil-Dunne, Iona; Achur, Rajeshwara N.; Agbor-Enoh, Sean T.; Valiyaveettil, Manojkumar; Naik, Ramachandra S.; Ockenhouse, Christian F.; Zhou, Ainong; Megnekou, Rosette; Leke, Rose; Taylor, Diane W.; Gowda, D. Channe

    2001-01-01

    During pregnancy, Plasmodium falciparum-infected erythrocytes sequester in the placenta by adhering to chondroitin 4-sulfate, creating a risk factor for both the mother and the fetus. The primigravidae are at higher risk for placental malaria than the multigravidae. This difference in susceptibility has been attributed to the lack of antibodies that block the adhesion of infected erythrocytes to placental chondroitin 4-sulfate in primigravid women. However, recent results show that many primigravidae at term have antibody levels similar to those of multigravidae, and thus the significance of antiadhesion antibodies in providing protection against malaria during pregnancy remains unclear. In this study, we analyzed plasma samples from women of various gravidities at different gestational stages for antiadhesion antibodies. The majority of women, regardless of gravidity, had similar levels of antibodies at term. Most primigravidae had low levels of or no antiadhesion antibodies prior to ∼20 weeks of pregnancy and then produced antibodies. Multigravidae also lacked antibodies until ∼12 weeks of pregnancy, but thereafter they efficiently produced antibodies. In pregnant women who had placental infection at term, higher levels of antiadhesion antibodies correlated with lower levels of placental parasitemia. The difference in kinetics of antibody production between primigravidae and multigravidae correlated with the prevalence of malaria in these groups, suggesting that antibodies are produced during pregnancy in response to placental infection. The early onset of efficient antibody response in multigravidae and the delayed production to antibodies in primigravidae appear to account for the gravidity-dependent differential susceptibilities of pregnant women to placental malaria. PMID:11705924

  3. A Pilot Randomised Trial of Induced Blood-Stage Plasmodium falciparum Infections in Healthy Volunteers for Testing Efficacy of New Antimalarial Drugs

    PubMed Central

    McCarthy, James S.; Sekuloski, Silvana; Griffin, Paul M.; Elliott, Suzanne; Douglas, Nanette; Peatey, Chris; Rockett, Rebecca; O'Rourke, Peter; Marquart, Louise; Hermsen, Cornelius; Duparc, Stephan; Möhrle, Jörg; Trenholme, Katharine R.; Humberstone, Andrew J.

    2011-01-01

    Background Critical to the development of new drugs for treatment of malaria is the capacity to safely evaluate their activity in human subjects. The approach that has been most commonly used is testing in subjects with natural malaria infection, a methodology that may expose symptomatic subjects to the risk of ineffective treatment. Here we describe the development and pilot testing of a system to undertake experimental infection using blood stage Plasmodium falciparum parasites (BSP). The objectives of the study were to assess the feasibility and safety of induced BSP infection as a method for assessment of efficacy of new drug candidates for the treatment of P. falciparum infection. Methods and Findings A prospective, unblinded, Phase IIa trial was undertaken in 19 healthy, malaria-naïve, male adult volunteers who were infected with BSP and followed with careful clinical and laboratory observation, including a sensitive, quantitative malaria PCR assay. Volunteers were randomly allocated to treatment with either of two licensed antimalarial drug combinations, artemether–lumefantrine (A/L) or atovaquone-proguanil (A/P). In the first cohort (n = 6) where volunteers received ∼360 BSP, none reached the target parasitemia of 1,000 before the day designated for antimalarial treatment (day 6). In the second and third cohorts, 13 volunteers received 1,800 BSP, with all reaching the target parasitemia before receiving treatment (A/L, n = 6; A/P, n = 7) The study demonstrated safety in the 19 volunteers tested, and a significant difference in the clearance kinetics of parasitemia between the drugs in the 13 evaluable subjects, with mean parasite reduction ratios of 759 for A/L and 17 for A/P (95% CI 120–4786 and 7–40 respectively; p<0.01). Conclusions This system offers a flexible and safe approach to testing the in vivo activity of novel antimalarials. Trial Registration: ClinicalTrials.gov NCT01055002 PMID:21887214

  4. Peripheral blood stem cell transplant-related Plasmodium falciparum infection in a patient with sickle cell disease.

    PubMed

    Mejia, Rojelio; Booth, Garrett S; Fedorko, Daniel P; Hsieh, Matthew M; Khuu, Hanh M; Klein, Harvey G; Mu, Jianbing; Fahle, Gary; Nutman, Thomas B; Su, Xin-Zhuan; Williams, Esther C; Flegel, Willy A; Klion, Amy

    2012-12-01

    Although transmission of Plasmodium falciparum (Pf) infection during red blood cell (RBC) transfusion from an infected donor has been well documented, malaria parasites are not known to infect hematopoietic stem cells. We report a case of Pf infection in a patient 11 days after peripheral blood stem cell transplant for sickle cell disease. Malaria parasites were detected in thick blood smears by Giemsa staining. Pf HRP2 antigen was measured by enzyme-linked immunosorbent assay on whole blood and plasma. Pf DNA was detected in whole blood and stem cell retention samples by real-time polymerase chain reaction using Pf species-specific primers and probes. Genotyping of eight Pf microsatellites was performed on genomic DNA extracted from whole blood. Pf was not detected by molecular, serologic, or parasitologic means in samples from the recipient until Day 11 posttransplant, coincident with the onset of symptoms. In contrast, Pf antigen was retrospectively detected in stored plasma collected 3 months before transplant from the asymptomatic donor. Pf DNA was detected in whole blood from both the donor and the recipient after transplant, and genotyping confirmed shared markers between donor and recipient Pf strains. Lookback analysis of RBC donors was negative for Pf infection. These findings are consistent with transmission by the stem cell product and have profound implications with respect to the screening of potential stem cell donors and recipients from malaria-endemic regions. © 2012 American Association of Blood Banks.

  5. Efficacy of mefloquine and sulfadoxine-pyrimethamine for the treatment of uncomplicated Plasmodium falciparum infection in Machinga District, Malawi, 1998.

    PubMed

    MacArthur, J; Stennies, G M; Macheso, A; Kolczak, M S; Green, M D; Ali, D; Barat, L M; Kazembe, P N; Ruebush, T K

    2001-12-01

    In response to the spread of chloroquine-resistant Plasmodium falciparum, Malaŵi changed its first-line antimalarial drug in 1993 from chloroquine to sulfadoxine-pyrimethamine (SP). Surveillance data has suggested that resistance to SP may be increasing. We compared the efficacy of SP with a potential successor, mefloquine (MQ). By use of a modified World Health Organization in vivo protocol, children infected with P. falciparum were randomized to receive SP (sulfadoxine 25 mg/kg) or MQ (15 mg/kg). We observed combined RII and RIII parasitologic failures of 20.0 and 22.0% in the SP and MQ arms, respectively. Among those in the MQ arm, the relative hazard of failing with a Day 2 drug level < 500 ng/mL was 10.6 times higher than those with levels > or = 500 ng/mL. Given the decreased efficacy of the first-line antimalarial drug and the high failure rates of MQ at this lower dosage, Malaŵi should consider assessing the efficacy and feasibility of alternative drugs to treat uncomplicated falciparum malaria.

  6. Quantitative analysis of morphological alterations in Plasmodium falciparum infected red blood cells through theoretical interpretation of spectral measurements.

    PubMed

    Serebrennikova, Yulia M; Patel, Janus; Milhous, Wilbur K; García-Rubio, Luis H

    2010-08-21

    Spectroscopic analysis can provide valuable insights into morphological and biochemical cellular transformations caused by diseases. However, traditional spectroscopic methods and the corresponding spectral interpretation approaches have been challenged by the complexities of the cell shape, orientation, and internal structure. Here we present an elegant spectral interpretation model that enables accurate quantitative analysis of the UV-visible spectra of red blood cells (RBCs) parasitized by the lethal human malaria parasite, Plasmodium falciparum. The model is based on the modified Mie theory (MMT) approach that incorporates the effects of the nonsphericity and orientation and multilayered cell structure to account for complex composition of the infected RBCs (IRBCs). We determine the structure and composition of the IRBCs and address unresolved matters over the alterations induced by the intraerythrocytic development of P. falciparum. The results indicate deformation and swelling of the IRBCs during the trophozoite stage of P. falciparum that is followed by substantial shrinkage during the schizont stages. We determine that up to 90% depletion of hemoglobin from the RBC cytosol does not lead to a net loss of iron from the infected cells. We quantitatively follow the morphological changes in the parasites during the intraerythrocytic development by applying the interpretation model to the UV-visible spectroscopic measurements of the IRBCs. We expect this method of quantitative spectroscopic characterization of the diseased cells to have practical clinical utility for rapid diagnosis, therapeutic monitoring, and drug susceptibility testing.

  7. Longitudinal study of Plasmodium falciparum infection and immune responses in infants with or without the sickle cell trait.

    PubMed

    Le Hesran, J Y; Personne, I; Personne, P; Fievet, N; Dubois, B; Beyemé, M; Boudin, C; Cot, M; Deloron, P

    1999-08-01

    Individuals may be homozygous (SS) or heterozygous (AS) sickle cell gene carriers or have normal adult haemoglobin (AA). Haemoglobin S could have a protective role against malaria but evidence is sparse and the operating mechanisms are poorly known. We followed two cohorts of children. The first was enrolled at birth (156 newborn babies) and the second at 24-36 months old (84 children). Both cohorts were followed for 30 months; monthly for parasitological data and half yearly for immunological data. In the first cohort, 22%, and in the second 13% of children were AS. Whatever their age parasite prevalence rates were similar in AA and AS individuals. Mean parasite densities increased less rapidly with age in AS than in AA children, and were significantly lower in AS than in AA children >48 months old. The AA children tended to be more often admitted to hospital than AS children (22% versus 11%, NS). Both anti-Plasmodium falciparum and anti-Pfl55/RESA antibody rates increased more rapidly in AA than in AS children. Conversely, the prevalence rate of cellular responders to the Pfl55/RESA antigen was similar in AA and AS children during the first 2 years of life, then it was higher in AS than in AA children. Sickle cell trait related antimalarial protection varies with age. The role of the modifications of the specific immune response to P. falciparum in explaining the protection of AS children against malaria is discussed.

  8. Thermodynamic concepts in the study of microbial populations: age structure in Plasmodium falciparum infected red blood cells.

    PubMed

    Ferrer, Jordi; Prats, Clara; López, Daniel; Vidal-Mas, Jaume; Gargallo-Viola, Domingo; Guglietta, Antonio; Giró, Antoni

    2011-01-01

    Variability is a hallmark of microbial systems. On the one hand, microbes are subject to environmental heterogeneity and undergo changeable conditions in their immediate surroundings. On the other hand, microbial populations exhibit high cellular diversity. The relation between microbial diversity and variability of population dynamics is difficult to assess. This connection can be quantitatively studied from a perspective that combines in silico models and thermodynamic methods and interpretations. The infection process of Plasmodium falciparum parasitizing human red blood cells under laboratory cultivation conditions is used to illustrate the potential of Individual-based models in the context of predictive microbiology and parasitology. Experimental data from several in vitro cultures are compared to the outcome of an individual-based model and analysed from a thermodynamic perspective. This approach allows distinguishing between intrinsic and external constraints that give rise to the diversity in the infection forms, and it provides a criterion to quantitatively define transient and stationary regimes in the culture. Increasing the ability of models to discriminate between different states of microbial populations enhances their predictive capability which finally leads to a better the control over culture systems. The strategy here presented is of general application and it can substantially improve modelling of other types of microbial communities.

  9. Levels and interactions of plasma xanthine oxidase, catalase and liver function parameters in Nigerian children with Plasmodium falciparum infection.

    PubMed

    Iwalokun, B A; Bamiro, S B; Ogunledun, A

    2006-12-01

    Elevated plasma levels of xanthine oxidase and liver function parameters have been associated with inflammatory events in several human diseases. While xanthine oxidase provides in vitro protection against malaria, its pathophysiological functions in vivo and interactions with liver function parameters remain unclear. This study examined the interactions and plasma levels of xanthine oxidase (XO) and uric acid (UA), catalase (CAT) and liver function parameters GOT, GPT and bilirubin in asymptomatic (n=20), uncomplicated (n=32), and severe (n=18) falciparum malaria children aged 3-13 years. Compared to age-matched control (n=16), significant (p<0.05) elevation in xanthine oxidase by 100-550%, uric acid by 15.4-153.8%, GOT and GPT by 22.1-102.2%, and total bilirubin by 2.3-86% according to parasitaemia (geometric mean parasite density (GMPD)=850-87100 parasites/microL) was observed in the malarial children. Further comparison with control revealed higher CAT level (16.2+/-0.5 vs 14.6+/-0.4 U/L; p<0.05) lacking significant (p>0.05) correlation with XO, but lower CAT level (13.4-5.4 U/L) with improved correlations (r=-0.53 to -0.91; p<0.05) with XO among the asymptomatic and symptomatic malaria children studied. 75% of control, 45% of asymptomatic, 21.9% of uncomplicated, and none of severe malaria children had Hb level>11.0 g/dL. Multivariate analyses further revealed significant (p<0.05) correlations between liver function parameters and xanthine oxidase (r=0.57-0.64) only in the severe malaria group. We conclude that elevated levels of XO and liver enzymes are biochemical features of Plasmodium falciparum parasitaemia in Nigerian children, with both parameters interacting differently to modulate the catalase response in asymptomatic and symptomatic falciparum malaria.

  10. 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

  11. Passive immunoprotection of Plasmodium falciparum-infected mice designates the CyRPA as candidate malaria vaccine antigen.

    PubMed

    Dreyer, Anita M; Matile, Hugues; Papastogiannidis, Petros; Kamber, Jolanda; Favuzza, Paola; Voss, Till S; Wittlin, Sergio; Pluschke, Gerd

    2012-06-15

    An effective malaria vaccine could prove to be the most cost-effective and efficacious means of preventing severe disease and death from malaria. In an endeavor to identify novel vaccine targets, we tested predicted Plasmodium falciparum open reading frames for proteins that elicit parasite-inhibitory Abs. This has led to the identification of the cysteine-rich protective Ag (CyRPA). CyRPA is a cysteine-rich protein harboring a predicted signal sequence. The stage-specific expression of CyRPA in late schizonts resembles that of proteins known to be involved in merozoite invasion. Immunofluorescence staining localized CyRPA at the apex of merozoites. The entire protein is conserved as shown by sequencing of the CyRPA encoding gene from a diverse range of P. falciparum isolates. CyRPA-specific mAbs substantially inhibited parasite growth in vitro as well as in a P. falciparum animal model based on NOD-scid IL2Rγ(null) mice engrafted with human erythrocytes. In contrast to other P. falciparum mouse models, this system generated very consistent results and evinced a dose-response relationship and therefore represents an unprecedented in vivo model for quantitative comparison of the functional potencies of malaria-specific Abs. Our data suggest a role for CyRPA in erythrocyte invasion by the merozoite. Inhibition of merozoite invasion by CyRPA-specific mAbs in vitro and in vivo renders this protein a promising malaria asexual blood-stage vaccine candidate Ag.

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

    PubMed

    Zipprer, Elizabeth M; Neggers, McKinzie; Kushwaha, Ambuj; Rayavara, Kempaiah; Desai, Sanjay A

    2014-05-18

    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. 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. 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++. 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.

  13. Functional state of the plasma membrane Ca2+ pump in Plasmodium falciparum-infected human red blood cells.

    PubMed

    Tiffert, T; Staines, H M; Ellory, J C; Lew, V L

    2000-05-15

    The active Ca2+ transport properties of malaria-infected, intact red blood cells are unknown. We report here the first direct measurements of Ca2+ pump activity in human red cells infected with Plasmodium falciparum, at the mature, late trophozoite stage. Ca2+ pump activity was measured by the Co2+-exposure method adapted for use in low-K+ media, optimal for parasitised cells. This required a preliminary study in normal, uninfected red cells of the effects of cell volume, membrane potential and external Na+/K+ concentrations on Ca2+ pump performance. Pump-mediated Ca2+ extrusion in normal red cells was only slightly lower in low-K+ media relative to high-K+ media despite the large differences in membrane potential predicted by the Lew-Bookchin red cell model. The effect was prevented by clotrimazole, an inhibitor of the Ca2+-sensitive K+ (KCa) channel, suggesting that it was due to minor cell dehydration. The Ca2+-saturated Ca2+ extrusion rate through the Ca2+ pump (Vmax) of parasitised red cells was marginally inhibited (2-27 %) relative to that of both uninfected red cells from the malaria-infected culture (cohorts), and uninfected red cells from the same donor kept under identical conditions (co-culture). Thus, Ca2+ pump function is largely conserved in parasitised cells up to the mature, late trophozoite stage. A high proportion of the ionophore-induced Ca2+ load in parasitised red cells is taken up by cytoplasmic Ca2+ buffers within the parasite. Following pump-mediated Ca2+ removal from the host, there remained a large residual Ca2+ pool within the parasite which slowly leaked to the host cell, from which it was pumped out.

  14. [Symptomatic and asymptomatic Plasmodium falciparum infection in children from 6 months to 6 years old in the Abobo general hospital (Abidjan, Côte d'Ivoire)].

    PubMed

    Assoumou, A; Adoubryn, K D; Aboum, K S; Kouadio-Yapo, C G; Ouhon, J

    2008-02-01

    It is commonly admitted that people living in malarial zone are carrying asymptomatic Plasmodium. Côte d'Ivoire is one of these zones. The studies carried out on malaria in these areas have focused mainly on the clinical forms of the disease and effectiveness of the antimalarial drugs. The purpose of this study was to determine the prevalence of the symptomatic and asymptomatic carriage of Plasmodium falciparum in children of 6 months to 180 months old in the Abidjan area. Over a period of twelve months, 902 feverish subjects and 681 non-feverish subjects were selected among the 7,017 people admitted in the paediatrics service of the Abobo general hospital for detection of malaria parasite. Among 1,583 selected subjects, 358 were carrying Plasmodium falciparum implying a total prevalence rate of 22.6%. The prevalence rate was 13.5% and 29.5% respectively in the asymptomatic subjects and symptomatic subjects. The highest proportions of positive thick smears were observed during the long rainy and dry seasons but, parasitaemia was the highest during the short dry season. In 31.5% of the cases, the asymptomatic carriers had a parasitic density higher or equal to 10,000 trophozoites/microl of blood and fever was not related to parasitic load. The prevalence rates of Plasmodium carriage and malaria were higher during the long rainy season. This study highlighted a considerable proportion of asymptomatic Plasmodium falciparum carriers. Improving environmental conditions should help to reduce this rate of carriage.

  15. Disparities of Plasmodium falciparum infection, malaria-related morbidity and access to malaria prevention and treatment among school-aged children: a national cross-sectional survey in Côte d'Ivoire.

    PubMed

    Houngbedji, Clarisse A; N'Dri, Prisca B; Hürlimann, Eveline; Yapi, Richard B; Silué, Kigbafori D; Soro, Gotianwa; Koudou, Benjamin G; Acka, Cinthia A; Assi, Serge-Brice; Vounatsou, Penelope; N'Goran, Eliézer K; Fantodji, Agathe; Utzinger, Jürg; Raso, Giovanna

    2015-01-05

    There is limited knowledge on the malaria burden of school-aged children in Côte d'Ivoire. The aim of this study was to assess Plasmodium falciparum infection, malaria-related morbidity, use of preventive measures and treatment against malaria, and physical access to health structures among school-aged children across Côte d'Ivoire. A national, cross-sectional study was designed, consisting of clinical and parasitological examinations and interviews with schoolchildren. More than 5,000 children from 93 schools in Côte d'Ivoire were interviewed to determine household socioeconomic status, self-reported morbidity and means of malaria prevention and treatment. Finger-prick blood samples were collected and Plasmodium infection and parasitaemia determined using Giemsa-stained blood films and a rapid diagnostic test (RDT). Haemoglobin levels and body temperature were measured. Children were classified into wealth quintiles using household assets and principal components analysis (PCA). The concentration index was employed to determine significant trends of health variables according to wealth quintiles. Logistic and binomial negative regression analyses were done to investigate for associations between P. falciparum prevalence and parasitaemia and any health-related variable. The prevalence of P. falciparum was 73.9% according to combined microscopy and RDT results with a geometric mean of parasitaemia among infected children of 499 parasites/μl of blood. Infection with P. falciparum was significantly associated with sex, socioeconomic status and study setting, while parasitaemia was associated with age. The rate of bed net use was low compared to the rate of bed net ownership. Preventive measures (bed net ownership, insecticide spray and the reported use of malaria treatment) were more frequently mentioned by children from wealthier households who were at lower risk of P. falciparum infection. Self-reported morbidity (headache) and clinical morbidity (anaemia) were

  16. Primaquine for reducing Plasmodium falciparum transmission.

    PubMed

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

    2012-09-12

    Mosquitoes become infected with malaria when they ingest gametocyte stages of the parasite from the blood of a human host. Plasmodium falciparum gametocytes are sensitive to the drug primaquine (PQ). The World Health Organization (WHO) recommends giving a single dose or short course of PQ alongside primary treatment for people ill with P. falciparum infection to reduce malaria transmission. Gametocytes themselves cause no symptoms, so this intervention does not directly benefit individuals. PQ causes haemolysis in some people with glucose-6-phosphate dehydrogenase (G6PD) deficiency so may not be safe.   To assess whether a single dose or short course of PQ added to treatments for malaria caused by P. falciparum infection reduces malaria transmission and is safe. We searched the following databases up to 10 April 2012 for studies: 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 we contacted likely researchers and organizations for relevant trials. Trials of mass treatment of whole populations (or actively detected fever or malaria cases within such populations) with antimalarial drugs, compared to treatment with the same drug plus PQ; or patients with clinical malaria being treated for malaria at health facilities randomized to short course/single dose PQ versus no PQ. Two authors (PMG and HG) independently screened all abstracts, applied inclusion criteria, and abstracted data. We sought data on the effect of PQ on malaria transmission intensity, participant infectiousness, the number of participants with gametocytes, and gametocyte density over time. We stratified results by primary treatment drug as

  17. Genome wide linkage study, using a 250K SNP map, of Plasmodium falciparum infection and mild malaria attack in a Senegalese population.

    PubMed

    Milet, Jacqueline; Nuel, Gregory; Watier, Laurence; Courtin, David; Slaoui, Yousri; Senghor, Paul; Migot-Nabias, Florence; Gaye, Oumar; Garcia, André

    2010-07-15

    Multiple factors are involved in the variability of host's response to P. falciparum infection, like the intensity and seasonality of malaria transmission, the virulence of parasite and host characteristics like age or genetic make-up. Although admitted nowadays, the involvement of host genetic factors remains unclear. Discordant results exist, even concerning the best-known malaria resistance genes that determine the structure or function of red blood cells. Here we report on a genome-wide linkage and association study for P. falciparum infection intensity and mild malaria attack among a Senegalese population of children and young adults from 2 to 18 years old. A high density single nucleotide polymorphisms (SNP) genome scan (Affimetrix GeneChip Human Mapping 250K-nsp) was performed for 626 individuals: i.e. 249 parents and 377 children out of the 504 ones included in the follow-up. The population belongs to a unique ethnic group and was closely followed-up during 3 years. Genome-wide linkage analyses were performed on four clinical and parasitological phenotypes and association analyses using the family based association tests (FBAT) method were carried out in regions previously linked to malaria phenotypes in literature and in the regions for which we identified a linkage peak. Analyses revealed three strongly suggestive evidences for linkage: between mild malaria attack and both the 6p25.1 and the 12q22 regions (empirical p-value=5x10(-5) and 9x10(-5) respectively), and between the 20p11q11 region and the prevalence of parasite density in asymptomatic children (empirical p-value=1.5x10(-4)). Family based association analysis pointed out one significant association between the intensity of plasmodial infection and a polymorphism located in ARHGAP26 gene in the 5q31-q33 region (p-value=3.7x10(-5)). This study identified three candidate regions, two of them containing genes that could point out new pathways implicated in the response to malaria infection

  18. Genome Wide Linkage Study, Using a 250K SNP Map, of Plasmodium falciparum Infection and Mild Malaria Attack in a Senegalese Population

    PubMed Central

    Milet, Jacqueline; Nuel, Gregory; Watier, Laurence; Courtin, David; Slaoui, Yousri; Senghor, Paul; Migot-Nabias, Florence; Gaye, Oumar; Garcia, André

    2010-01-01

    Multiple factors are involved in the variability of host's response to P. falciparum infection, like the intensity and seasonality of malaria transmission, the virulence of parasite and host characteristics like age or genetic make-up. Although admitted nowadays, the involvement of host genetic factors remains unclear. Discordant results exist, even concerning the best-known malaria resistance genes that determine the structure or function of red blood cells. Here we report on a genome-wide linkage and association study for P. falciparum infection intensity and mild malaria attack among a Senegalese population of children and young adults from 2 to 18 years old. A high density single nucleotide polymorphisms (SNP) genome scan (Affimetrix GeneChip Human Mapping 250K-nsp) was performed for 626 individuals: i.e. 249 parents and 377 children out of the 504 ones included in the follow-up. The population belongs to a unique ethnic group and was closely followed-up during 3 years. Genome-wide linkage analyses were performed on four clinical and parasitological phenotypes and association analyses using the family based association tests (FBAT) method were carried out in regions previously linked to malaria phenotypes in literature and in the regions for which we identified a linkage peak. Analyses revealed three strongly suggestive evidences for linkage: between mild malaria attack and both the 6p25.1 and the 12q22 regions (empirical p-value = 5×10−5 and 9×10−5 respectively), and between the 20p11q11 region and the prevalence of parasite density in asymptomatic children (empirical p-value = 1.5×10−4). Family based association analysis pointed out one significant association between the intensity of plasmodial infection and a polymorphism located in ARHGAP26 gene in the 5q31–q33 region (p-value = 3.7×10−5). This study identified three candidate regions, two of them containing genes that could point out new pathways implicated in the response to

  19. Chemotherapeutic strategies for reducing transmission of Plasmodium vivax malaria.

    PubMed

    Douglas, Nicholas M; John, George K; von Seidlein, Lorenz; Anstey, Nicholas M; Price, Ric N

    2012-01-01

    Effective use of anti-malarial drugs is key to reducing the transmission potential of Plasmodium vivax. In patients presenting with symptomatic disease, treatment with potent and relatively slowly eliminated blood schizontocidal regimens administered concurrently with a supervised course of 7 mg/kg primaquine over 7-14 days has potential to exert the greatest transmission-blocking benefit. Given the spread of chloroquine-resistant P. vivax strains, the artemisinin combination therapies dihydroartemisinin + piperaquine and artesunate + mefloquine are currently the most assured means of preventing P. vivax recrudescence. Preliminary evidence suggests that, like chloroquine, these combinations potentiate the hypnozoitocidal effect of primaquine, but further supportive evidence is required. In view of the high rate of P. vivax relapse following falciparum infections in co-endemic regions, there is a strong argument for broadening current radical cure policy to include the administration of hypnozoitocidal doses of primaquine to patients with Plasmodium falciparum malaria. The most important reservoir for P. vivax transmission is likely to be very low-density, asymptomatic infections, the majority of which will arise from liver-stage relapses. Therefore, judicious mass administration of hypnozoitocidal therapy will reduce transmission of P. vivax to a greater extent than strategies focused on treatment of symptomatic patients. An efficacious hypnozoitocidal agent with a short curative treatment course would be particularly useful in mass drug administration campaigns.

  20. Prime-boost vaccination with chimpanzee adenovirus and modified vaccinia Ankara encoding TRAP provides partial protection against Plasmodium falciparum infection in Kenyan adults

    PubMed Central

    Edwards, Nick J.; Roberts, Rachel; Mwacharo, Jedidah; Bowyer, Georgina; Bliss, Carly; Hodgson, Susanne H.; Njuguna, Patricia; Viebig, Nicola K.; Nicosia, Alfredo; Gitau, Evelyn; Douglas, Sandy; Illingworth, Joe; Marsh, Kevin; Lawrie, Alison; Imoukhuede, Egeruan B.; Ewer, Katie

    2015-01-01

    Protective immunity to the liver stage of the malaria parasite can be conferred by vaccine-induced T cells, but no subunit vaccination approach based on cellular immunity has shown efficacy in field studies. We randomly allocated 121 healthy adult male volunteers in Kilifi, Kenya, to vaccination with the recombinant viral vectors chimpanzee adenovirus 63 (ChAd63) and modified vaccinia Ankara (MVA), both encoding the malaria peptide sequence ME-TRAP (the multiple epitope string and thrombospondin-related adhesion protein), or to vaccination with rabies vaccine as a control. We gave antimalarials to clear parasitemia and conducted PCR (polymerase chain reaction) analysis on blood samples three times a week to identify infection with the malaria parasite Plasmodium falciparum. On Cox regression, vaccination reduced the risk of infection by 67% [95% confidence interval (CI), 33 to 83%; P = 0.002] during 8 weeks of monitoring. T cell responses to TRAP peptides 21 to 30 were significantly associated with protection (hazard ratio,0.24; 95% CI, 0.08 to 0.75; P = 0.016). PMID:25947165

  1. Prime-boost vaccination with chimpanzee adenovirus and modified vaccinia Ankara encoding TRAP provides partial protection against Plasmodium falciparum infection in Kenyan adults.

    PubMed

    Ogwang, Caroline; Kimani, Domtila; Edwards, Nick J; Roberts, Rachel; Mwacharo, Jedidah; Bowyer, Georgina; Bliss, Carly; Hodgson, Susanne H; Njuguna, Patricia; Viebig, Nicola K; Nicosia, Alfredo; Gitau, Evelyn; Douglas, Sandy; Illingworth, Joe; Marsh, Kevin; Lawrie, Alison; Imoukhuede, Egeruan B; Ewer, Katie; Urban, Britta C; S Hill, Adrian V; Bejon, Philip

    2015-05-06

    Protective immunity to the liver stage of the malaria parasite can be conferred by vaccine-induced T cells, but no subunit vaccination approach based on cellular immunity has shown efficacy in field studies. We randomly allocated 121 healthy adult male volunteers in Kilifi, Kenya, to vaccination with the recombinant viral vectors chimpanzee adenovirus 63 (ChAd63) and modified vaccinia Ankara (MVA), both encoding the malaria peptide sequence ME-TRAP (the multiple epitope string and thrombospondin-related adhesion protein), or to vaccination with rabies vaccine as a control. We gave antimalarials to clear parasitemia and conducted PCR (polymerase chain reaction) analysis on blood samples three times a week to identify infection with the malaria parasite Plasmodium falciparum. On Cox regression, vaccination reduced the risk of infection by 67% [95% confidence interval (CI), 33 to 83%; P = 0.002] during 8 weeks of monitoring. T cell responses to TRAP peptides 21 to 30 were significantly associated with protection (hazard ratio, 0.24; 95% CI, 0.08 to 0.75; P = 0.016).

  2. 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 Central

    Adams, Yvonne; Kuhnrae, Pongsak; Higgins, Matthew K.; Ghumra, Ashfaq

    2014-01-01

    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. PMID:24343658

  3. 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.

  4. Evaluation of the 4-pyridinemethanol WR 180,409 (enpiroline) in the treatment of induced Plasmodium falciparum infections in healthy, non-immune subjects.

    PubMed

    Cosgriff, T M; Boudreau, E F; Pamplin, C L; Berman, J D; Shmuklarsky, M J; Canfield, C J

    1984-09-01

    WR 180,409 (enpiroline) was administered to 22 non-immune subjects infected with the multi-drug resistant Vietnam Smith isolate of Plasmodium falciparum. It was curative in single day treatment regimens with a minimum curative dose of approximately 10 mg/kg body weight. At this dose level it was well tolerated and produced rapid clearance of parasitemia in every case.

  5. Safety, Immunogenicity and Efficacy of Prime-Boost Vaccination with ChAd63 and MVA Encoding ME-TRAP against Plasmodium falciparum Infection in Adults in Senegal

    PubMed Central

    Mensah, Victorine A.; Gueye, Aly; Ndiaye, Magatte; Edwards, Nick J.; Wright, Danny; Anagnostou, Nicholas A.; Syll, Massamba; Ndaw, Amy; Abiola, Annie; Bliss, Carly; Gomis, Jules-François; Petersen, Ines; Ogwang, Caroline; Dieye, Tandakha; Viebig, Nicola K.; Lawrie, Alison M.; Roberts, Rachel; Nicosia, Alfredo; Faye, Babacar; Gaye, Oumar; Leroy, Odile; Ewer, Katie J.; Bejon, Philip; Hill, Adrian V. S.; Cisse, Badara

    2016-01-01

    Malaria transmission is in decline in some parts of Africa, partly due to the scaling up of control measures. If the goal of elimination is to be achieved, additional control measures including an effective and durable vaccine will be required. Studies utilising the prime-boost approach to deliver viral vectors encoding the pre-erythrocytic antigen ME-TRAP (multiple epitope thrombospondin-related adhesion protein) have shown promising safety, immunogenicity and efficacy in sporozoite challenge studies. More recently, a study in Kenyan adults, similar to that reported here, showed substantial efficacy against P. falciparum infection. One hundred and twenty healthy male volunteers, living in a malaria endemic area of Senegal were randomised to receive either the Chimpanzee adenovirus (ChAd63) ME-TRAP as prime vaccination, followed eight weeks later by modified vaccinia Ankara (MVA) also encoding ME-TRAP as booster, or two doses of anti-rabies vaccine as a comparator. Prior to follow-up, antimalarials were administered to clear parasitaemia and then participants were monitored by PCR for malaria infection for eight weeks. The primary endpoint was time-to-infection with P. falciparum malaria, determined by two consecutive positive PCR results. Secondary endpoints included adverse event reporting, measures of cellular and humoral immunogenicity and a meta-analysis of combined vaccine efficacy with the parallel study in Kenyan adults.We show that this pre-erythrocytic malaria vaccine is safe and induces significant immunogenicity, with a peak T-cell response at seven days after boosting of 932 Spot Forming Cells (SFC)/106 Peripheral Blood Mononuclear Cells(PBMC) compared to 57 SFC/ 106 PBMCs in the control group. However, a vaccine efficacy was not observed: 12 of 57 ME-TRAP vaccinees became PCR positive during the intensive monitoring period as compared to 13 of the 58 controls (P = 0.80). This trial confirms that vaccine efficacy against malaria infection in adults may

  6. Nutritional and socio-economic factors associated with Plasmodium falciparum infection in children from Equatorial Guinea: results from a nationally representative survey

    PubMed Central

    Custodio, Estefanía; Descalzo, Miguel Ángel; Villamor, Eduardo; Molina, Laura; Sánchez, Ignacio; Lwanga, Magdalena; Bernis, Cristina; Benito, Agustín; Roche, Jesús

    2009-01-01

    Background Malaria has traditionally been a major endemic disease in Equatorial Guinea. Although parasitaemia prevalence on the insular region has been substantially reduced by vector control in the past few years, the prevalence in the mainland remains over 50% in children younger than five years. The aim of this study is to investigate the risk factors for parasitaemia and treatment seeking behaviour for febrile illness at country level, in order to provide evidence that will reinforce the EG National Malaria Control Programme. Methods The study was a cross-sectional survey of children 0 to 5 years old, using a multistaged, stratified, cluster-selected sample at the national level. It included a socio-demographic, health and dietary questionnaires, anthropometric measurements, and thick and thin blood smears to determine the Plasmodium infection. A multivariate logistic regression model was used to determine risk factors for parasitaemia, taking into account the cluster design. Results The overall prevalence of parasitemia was 50.9%; it was higher in rural (58.8%) compared to urban areas (44.0%, p = 0.06). Age was positively associated with parasitemia (p < 0.0001). In rural areas, risk factors included longer distance to health facilities (p = 0.01) and a low proportion of households with access to protected water in the community (p = 0.02). Having had an episode of cough in the 15 days prior to the survey was inversely related to parasitemia (p = 0.04). In urban areas, the risk factors were stunting (p = 0.005), not having taken colostrum (p = 0.01), and that someone in the household slept under a bed net (p = 0.002); maternal antimalarial medication intake during pregnancy (p = 0.003) and the household socio-economic status (p = 0.0002) were negatively associated with parasitemia. Only 55% of children with fever were taken outside their homes for care, and treatment seeking behaviour differed substantially between rural and urban populations. Conclusion

  7. Selective permeabilization of the host cell membrane of Plasmodium falciparum-infected red blood cells with streptolysin O and equinatoxin II

    PubMed Central

    Jackson, Katherine E.; Spielmann, Tobias; Hanssen, Eric; Adisa, Akinola; Separovic, Frances; Dixon, Matthew W. A.; Trenholme, Katharine R.; Hawthorne, Paula L.; Gardiner, Don L.; Gilberger, Tim; Tilley, Leann

    2006-01-01

    Plasmodium falciparum develops within the mature RBCs (red blood cells) of its human host in a PV (parasitophorous vacuole) that separates the host cell cytoplasm from the parasite surface. The pore-forming toxin, SLO (streptolysin O), binds to cholesterol-containing membranes and can be used to selectively permeabilize the host cell membrane while leaving the PV membrane intact. We found that in mixtures of infected and uninfected RBCs, SLO preferentially lyses uninfected RBCs rather than infected RBCs, presumably because of differences in cholesterol content of the limiting membrane. This provides a means of generating pure preparations of viable ring stage infected RBCs. As an alternative permeabilizing agent we have characterized EqtII (equinatoxin II), a eukaryotic pore-forming toxin that binds preferentially to sphingomyelin-containing membranes. EqtII lyses the limiting membrane of infected and uninfected RBCs with similar efficiency but does not disrupt the PV membrane. It generates pores of up to 100 nm, which allow entry of antibodies for immunofluorescence and immunogold labelling. The present study provides novel tools for the analysis of this important human pathogen and highlights differences between Plasmodium-infected and uninfected RBCs. PMID:17155936

  8. Monitoring the uptake of glycosphingolipids in Plasmodium falciparum-infected erythrocytes using both fluorescence microscopy and capillary electrophoresis with laser-induced fluorescence detection.

    PubMed

    Essaka, David C; White, John; Rathod, Pradip; Whitmore, Colin D; Hindsgaul, Ole; Palcic, Monica M; Dovichi, Norman J

    2010-12-01

    The metabolism of glycosphingolipids by the malaria-causing parasite Plasmodium falciparum plays an important role in the progression of the disease. We report a new and highly sensitive method to monitor the uptake of glycosphingolipids in infected red blood cells (iRBCs). A tetramethylrhodamine-labeled glycosphingolipid (GM1-TMR) was used as a substrate. Uptake was demonstrated by fluorescence microscopy. The iRBCs were lysed with a 15% solution of saponin and washed with phosphate buffered saline to release intact parasites. The parasites were further lysed and the resulting homogenates were analyzed by capillary electrophoresis with laser-induced fluorescence detection. The lysate from erythrocytes infected at 1% parasitemia generated a signal 20 standard deviations larger than uninfected erythrocytes, which suggests that relatively low infection levels can be studied with this technique.

  9. Surface Co-Expression of Two Different PfEMP1 Antigens on Single Plasmodium falciparum-Infected Erythrocytes Facilitates Binding to ICAM1 and PECAM1

    PubMed Central

    Joergensen, Louise; Bengtsson, Dominique C.; Bengtsson, Anja; Ronander, Elena; Berger, Sanne S.; Turner, Louise; Dalgaard, Michael B.; Cham, Gerald K. K.; Victor, Michala E.; Lavstsen, Thomas; Theander, Thor G.; Arnot, David E.; Jensen, Anja T. R.

    2010-01-01

    The Plasmodium falciparum erythrocyte membrane protein 1 (PfEMP1) antigens play a major role in cytoadhesion of infected erythrocytes (IE), antigenic variation, and immunity to malaria. The current consensus on control of variant surface antigen expression is that only one PfEMP1 encoded by one var gene is expressed per cell at a time. We measured var mRNA transcript levels by real-time Q-PCR, analysed var gene transcripts by single-cell FISH and directly compared these with PfEMP1 antigen surface expression and cytoadhesion in three different antibody-selected P. falciparum 3D7 sub-lines using live confocal microscopy, flow cytometry and in vitro adhesion assays. We found that one selected parasite sub-line simultaneously expressed two different var genes as surface antigens, on single IE. Importantly, and of physiological relevance to adhesion and malaria pathogenesis, this parasite sub-line was found to bind both CD31/PECAM1 and CD54/ICAM1 and to adhere twice as efficiently to human endothelial cells, compared to infected cells having only one PfEMP1 variant on the surface. These new results on PfEMP1 antigen expression indicate that a re-evaluation of the molecular mechanisms involved in P. falciparum adhesion and of the accepted paradigm of absolutely mutually exclusive var gene transcription is required. PMID:20824088

  10. Surface co-expression of two different PfEMP1 antigens on single plasmodium falciparum-infected erythrocytes facilitates binding to ICAM1 and PECAM1.

    PubMed

    Joergensen, Louise; Bengtsson, Dominique C; Bengtsson, Anja; Ronander, Elena; Berger, Sanne S; Turner, Louise; Dalgaard, Michael B; Cham, Gerald K K; Victor, Michala E; Lavstsen, Thomas; Theander, Thor G; Arnot, David E; Jensen, Anja T R

    2010-09-02

    The Plasmodium falciparum erythrocyte membrane protein 1 (PfEMP1) antigens play a major role in cytoadhesion of infected erythrocytes (IE), antigenic variation, and immunity to malaria. The current consensus on control of variant surface antigen expression is that only one PfEMP1 encoded by one var gene is expressed per cell at a time. We measured var mRNA transcript levels by real-time Q-PCR, analysed var gene transcripts by single-cell FISH and directly compared these with PfEMP1 antigen surface expression and cytoadhesion in three different antibody-selected P. falciparum 3D7 sub-lines using live confocal microscopy, flow cytometry and in vitro adhesion assays. We found that one selected parasite sub-line simultaneously expressed two different var genes as surface antigens, on single IE. Importantly, and of physiological relevance to adhesion and malaria pathogenesis, this parasite sub-line was found to bind both CD31/PECAM1 and CD54/ICAM1 and to adhere twice as efficiently to human endothelial cells, compared to infected cells having only one PfEMP1 variant on the surface. These new results on PfEMP1 antigen expression indicate that a re-evaluation of the molecular mechanisms involved in P. falciparum adhesion and of the accepted paradigm of absolutely mutually exclusive var gene transcription is required.

  11. Identification of a Role for the PfEMP1 Semi-Conserved Head Structure in Protein Trafficking to the Surface of Plasmodium falciparum Infected Red Blood Cells

    PubMed Central

    Melcher, Martin; Muhle, Rebecca A.; Henrich, Philipp P.; Kraemer, Susan M.; Avril, Marion; Vigan-Womas, Ines; Mercereau-Puijalon, Odile; Smith, Joseph D.; Fidock, David A.

    2010-01-01

    Summary Transport of Plasmodium falciparum Erythrocyte Membrane Protein 1 (PfEMP1) variants to the red blood cell (RBC) surface enables malarial parasite evasion of host immunity by modifying the antigenic and adhesive properties of infected RBCs. In this study, we applied the Bxb1 integrase system to integrate transgenes encoding truncated PfEMP1-GFP fusions into cytoadherent A4 parasites and characterize their surface transport requirements. Our studies revealed that the semi-conserved head structure of PfEMP1 proteins, in combination with the predicted transmembrane region and cytoplasmic tail, encodes sufficient information for RBC surface display. In contrast, miniPfEMP1 proteins with truncated head structures were exported to the RBC cytoplasm but were not detected at the RBC surface by flow cytometry or immuno-electron microscopy. We demonstrated the absence of a mechanistic barrier to having native and miniPfEMP1 proteins displayed simultaneously at the RBC surface. However, surface exposed miniPfEMP1 proteins did not convey cytoadherence properties to their host cells, implicating potential steric considerations in host-receptor interactions or the need for multiple domains to mediate cell binding. This study establishes a new system to investigate PfEMP1 transport and demonstrates that the PfEMP1 semi-conserved head structure is under selection for protein transport, in addition to its known roles in adhesion. PMID:20438573

  12. Effect of nutrient deficiencies on in vitro Th1 and Th2 cytokine response of peripheral blood mononuclear cells to Plasmodium falciparum infection

    PubMed Central

    2010-01-01

    Background An appropriate balance between pro-inflammatory and anti-inflammatory cytokines that mediate innate and adaptive immune responses is required for effective protection against human malaria and to avoid immunopathology. In malaria endemic countries, this immunological balance may be influenced by micronutrient deficiencies. Methods Peripheral blood mononuclear cells from Tanzanian preschool children were stimulated in vitro with Plasmodium falciparum-parasitized red blood cells to determine T-cell responses to malaria under different conditions of nutrient deficiencies and malaria status. Results The data obtained indicate that zinc deficiency is associated with an increase in TNF response by 37%; 95% CI: 14% to 118% and IFN-γ response by 74%; 95% CI: 24% to 297%. Magnesium deficiency, on the other hand, was associated with an increase in production of IL-13 by 80%; 95% CI: 31% to 371% and a reduction in IFN-γ production. These results reflect a shift in cytokine profile to a more type I cytokine profile and cell-cell mediated responses in zinc deficiency and a type II response in magnesium deficiency. The data also reveal a non-specific decrease in cytokine production in children due to iron deficiency anaemia that is largely associated with malaria infection status. Conclusions The pathological sequels of malaria potentially depend more on the balance between type I and type II cytokine responses than on absolute suppression of these cytokines and this balance may be influenced by a combination of micronutrient deficiencies and malaria status. PMID:20546583

  13. Alterations in early cytokine-mediated immune responses to Plasmodium falciparum infection in Tanzanian children with mineral element deficiencies: a cross-sectional survey

    PubMed Central

    2010-01-01

    Background Deficiencies in vitamins and mineral elements are important causes of morbidity in developing countries, possibly because they lead to defective immune responses to infection. The aim of the study was to assess the effects of mineral element deficiencies on early innate cytokine responses to Plasmodium falciparum malaria. Methods Peripheral blood mononuclear cells from 304 Tanzanian children aged 6-72 months were stimulated with P. falciparum-parasitized erythrocytes obtained from in vitro cultures. Results The results showed a significant increase by 74% in geometric mean of TNF production in malaria-infected individuals with zinc deficiency (11% to 240%; 95% CI). Iron deficiency anaemia was associated with increased TNF production in infected individuals and overall with increased IL-10 production, while magnesium deficiency induced increased production of IL-10 by 46% (13% to 144%) in uninfected donors. All donors showed a response towards IL-1β production, drawing special attention for its possible protective role in early innate immune responses to malaria. Conclusions In view of these results, the findings show plasticity in cytokine profiles of mononuclear cells reacting to malaria infection under conditions of different micronutrient deficiencies. These findings lay the foundations for future inclusion of a combination of precisely selected set of micronutrients rather than single nutrients as part of malaria vaccine intervention programmes in endemic countries. PMID:20470442

  14. Identification of a role for the PfEMP1 semi-conserved head structure in protein trafficking to the surface of Plasmodium falciparum infected red blood cells.

    PubMed

    Melcher, Martin; Muhle, Rebecca A; Henrich, Philipp P; Kraemer, Susan M; Avril, Marion; Vigan-Womas, Ines; Mercereau-Puijalon, Odile; Smith, Joseph D; Fidock, David A

    2010-10-01

    Transport of Plasmodium falciparum Erythrocyte Membrane Protein 1 (PfEMP1) variants to the red blood cell (RBC) surface enables malarial parasite evasion of host immunity by modifying the antigenic and adhesive properties of infected RBCs. In this study, we applied the Bxb1 integrase system to integrate transgenes encoding truncated PfEMP1-GFP fusions into cytoadherent A4 parasites and characterize their surface transport requirements. Our studies revealed that the semi-conserved head structure of PfEMP1 proteins, in combination with the predicted transmembrane region and cytoplasmic tail, encodes sufficient information for RBC surface display. In contrast, miniPfEMP1 proteins with truncated head structures were exported to the RBC cytoplasm but were not detected at the RBC surface by flow cytometry or immuno-electron microscopy. We demonstrated the absence of a mechanistic barrier to having native and miniPfEMP1 proteins displayed simultaneously at the RBC surface. However, surface-exposed miniPfEMP1 proteins did not convey cytoadherence properties to their host cells, implicating potential steric considerations in host-receptor interactions or the need for multiple domains to mediate cell binding. This study establishes a new system to investigate PfEMP1 transport and demonstrates that the PfEMP1 semi-conserved head structure is under selection for protein transport, in addition to its known roles in adhesion.

  15. Label-free microfluidic enrichment of ring-stage Plasmodium falciparum-infected red blood cells using non-inertial hydrodynamic lift.

    PubMed

    Geislinger, Thomas M; Chan, Sherwin; Moll, Kirsten; Wixforth, Achim; Wahlgren, Mats; Franke, Thomas

    2014-09-20

    Understanding of malaria pathogenesis caused by Plasmodium falciparum has been greatly deepened since the introduction of in vitro culture system, but the lack of a method to enrich ring-stage parasites remains a technical challenge. Here, a novel way to enrich red blood cells containing parasites in the early ring stage is described and demonstrated. A simple, straight polydimethylsiloxane microchannel connected to two syringe pumps for sample injection and two height reservoirs for sample collection is used to enrich red blood cells containing parasites in the early ring stage (8-10 h p.i.). The separation is based on the non-inertial hydrodynamic lift effect, a repulsive cell-wall interaction that enables continuous and label-free separation with deformability as intrinsic marker. The possibility to enrich red blood cells containing P. falciparum parasites at ring stage with a throughput of ~12,000 cells per hour and an average enrichment factor of 4.3 ± 0.5 is demonstrated. The method allows for the enrichment of red blood cells early after the invasion by P. falciparum parasites continuously and without any need to label the cells. The approach promises new possibilities to increase the sensitivity of downstream analyses like genomic- or diagnostic tests. The device can be produced as a cheap, disposable chip with mass production technologies and works without expensive peripheral equipment. This makes the approach interesting for the development of new devices for field use in resource poor settings and environments, e.g. with the aim to increase the sensitivity of microscope malaria diagnosis.

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

    PubMed

    Teirlinck, Anne C; Roestenberg, Meta; Bijker, Else M; Hoffman, Stephen L; Sauerwein, Robert W; Scholzen, Anja

    2015-09-01

    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.).

  17. A nanovector with complete discrimination for targeted delivery to Plasmodium falciparum-infected versus non-infected red blood cells in vitro.

    PubMed

    Urbán, Patricia; Estelrich, Joan; Cortés, Alfred; Fernàndez-Busquets, Xavier

    2011-04-30

    Current administration methods of antimalarial drugs deliver the free compound in the blood stream, where it can be unspecifically taken up by all cells, and not only by Plasmodium-infected red blood cells (pRBCs). Nanosized carriers have been receiving special attention with the aim of minimizing the side effects of malaria therapy by increasing drug bioavailability and selectivity. Liposome encapsulation has been assayed for the delivery of compounds against murine malaria, but there is a lack of cellular studies on the performance of targeted liposomes in specific cell recognition and on the efficacy of cargo delivery, and very little data on liposome-driven antimalarial drug targeting to human-infecting parasites. We have used fluorescence microscopy to assess in vitro the efficiency of liposomal nanocarriers for the targeted delivery of their contents to pRBCs. 200-nm liposomes loaded with quantum dots were covalently functionalized with oriented, specific half-antibodies against P. falciparum late form-infected pRBCs. In less than 90min, liposomes dock to pRBC plasma membranes and release their cargo to the cell. 100.0% of late form-containing pRBCs and 0.0% of non-infected RBCs in P. falciparum cultures are recognized and permeated by the content of targeted immunoliposomes. Liposomes not functionalized with antibodies are also specifically directed to pRBCs, although with less affinity than immunoliposomes. In preliminary assays, the antimalarial drug chloroquine at a concentration of 2nM, ≥10 times below its IC(50) in solution, cleared 26.7±1.8% of pRBCs when delivered inside targeted immunoliposomes. Copyright © 2011 Elsevier B.V. All rights reserved.

  18. Safety and comparability of controlled human Plasmodium falciparum infection by mosquito bite in malaria-naïve subjects at a new facility for sporozoite challenge.

    PubMed

    Talley, Angela K; Healy, Sara A; Finney, Olivia C; Murphy, Sean C; Kublin, James; Salas, Carola J; Lundebjerg, Susan; Gilbert, Peter; Van Voorhis, Wesley C; Whisler, John; Wang, Ruobing; Ockenhouse, Chris F; Heppner, D Gray; Kappe, Stefan H; Duffy, Patrick E

    2014-01-01

    Controlled human malaria infection (CHMI) studies which recapitulate mosquito-borne infection are a critical tool to identify protective vaccine and drug candidates for advancement to field trials. In partnership with the Walter Reed Army Institute of Research, the CHMI model was established at the Seattle Biomedical Research Institute's Malaria Clinical Trials Center (MCTC). Activities and reagents at both centers were aligned to ensure comparability and continued safety of the model. To demonstrate successful implementation, CHMI was performed in six healthy malaria-naïve volunteers. All volunteers received NF54 strain Plasmodium falciparum by the bite of five infected Anopheles stephensi mosquitoes under controlled conditions and were monitored for signs and symptoms of malaria and for parasitemia by peripheral blood smear. Subjects were treated upon diagnosis with chloroquine by directly observed therapy. Immunological (T cell and antibody) and molecular diagnostic (real-time quantitative reverse transcriptase polymerase chain reaction [qRT-PCR]) assessments were also performed. All six volunteers developed patent parasitemia and clinical malaria. No serious adverse events occurred during the study period or for six months post-infection. The mean prepatent period was 11.2 days (range 9-14 days), and geometric mean parasitemia upon diagnosis was 10.8 parasites/µL (range 2-69) by microscopy. qRT-PCR detected parasites an average of 3.7 days (range 2-4 days) earlier than blood smears. All volunteers developed antibodies to the blood-stage antigen merozoite surface protein 1 (MSP-1), which persisted up to six months. Humoral and cellular responses to pre-erythrocytic antigens circumsporozoite protein (CSP) and liver-stage antigen 1 (LSA-1) were limited. The CHMI model was safe, well tolerated and characterized by consistent prepatent periods, pre-symptomatic diagnosis in 3/6 subjects and adverse event profiles as reported at established centers. The MCTC can now

  19. Changes in the levels of cytokines, chemokines and malaria-specific antibodies in response to Plasmodium falciparum infection in children living in sympatry in Mali.

    PubMed

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

    2012-04-05

    The Fulani are known to be less susceptible to Plasmodium falciparum malaria as reflected by lower parasitaemia and fewer clinical symptoms than other sympatric ethnic groups. So far most studies in these groups have been performed on adults, which is why little is known about these responses in children. This study was designed to provide more information on this gap. Circulating inflammatory factors and antibody levels in children from the Fulani and Dogon ethnic groups were measured. The inflammatory cytokines; interleukin (IL)-1beta, IL-6, IL-8, IL-10, IL-12p70, tumor necrosis factor (TNF) and the chemokines; regulated on activation normal T cell expressed and secreted (RANTES), monokine-induced by IFN-gamma (MIG), monocyte chemotactic protein (MCP)-1 and IFN-gamma-inducible protein (IP)-10 were measured by cytometric bead arrays. The levels of interferon (IFN)-alpha, IFN-gamma and malaria-specific antibodies; immunoglobulin (Ig) G, IgM and IgG subclasses (IgG1-IgG4) were measured by ELISA. The results revealed that the Fulani children had higher levels of all tested cytokines compared to the Dogon, in particular IFN-gamma, a cytokine known to be involved in parasite clearance. Out of all the tested chemokines, only MCP-1 was increased in the Fulani compared to the Dogon. When dividing the children into infected and uninfected individuals, infected Dogon had significantly lower levels of RANTES compared to their uninfected peers, and significantly higher levels of MIG and IP-10 as well as MCP-1, although the latter did not reach statistical significance. In contrast, such patterns were not seen in the infected Fulani children and their chemokine levels remained unchanged upon infection compared to uninfected counterparts. Furthermore, the Fulani also had higher titres of malaria-specific IgG and IgM as well as IgG1-3 subclasses compared to the Dogon. Taken together, this study demonstrates, in accordance with previous work, that Fulani children mount a stronger

  20. Changes in the levels of cytokines, chemokines and malaria-specific antibodies in response to Plasmodium falciparum infection in children living in sympatry in Mali

    PubMed Central

    2012-01-01

    Background The Fulani are known to be less susceptible to Plasmodium falciparum malaria as reflected by lower parasitaemia and fewer clinical symptoms than other sympatric ethnic groups. So far most studies in these groups have been performed on adults, which is why little is known about these responses in children. This study was designed to provide more information on this gap. Methods Circulating inflammatory factors and antibody levels in children from the Fulani and Dogon ethnic groups were measured. The inflammatory cytokines; interleukin (IL)-1beta, IL-6, IL-8, IL-10, IL-12p70, tumor necrosis factor (TNF) and the chemokines; regulated on activation normal T cell expressed and secreted (RANTES), monokine-induced by IFN-gamma (MIG), monocyte chemotactic protein (MCP)-1 and IFN-gamma-inducible protein (IP)-10 were measured by cytometric bead arrays. The levels of interferon (IFN)-alpha, IFN-gamma and malaria-specific antibodies; immunoglobulin (Ig) G, IgM and IgG subclasses (IgG1-IgG4) were measured by ELISA. Results The results revealed that the Fulani children had higher levels of all tested cytokines compared to the Dogon, in particular IFN-gamma, a cytokine known to be involved in parasite clearance. Out of all the tested chemokines, only MCP-1 was increased in the Fulani compared to the Dogon. When dividing the children into infected and uninfected individuals, infected Dogon had significantly lower levels of RANTES compared to their uninfected peers, and significantly higher levels of MIG and IP-10 as well as MCP-1, although the latter did not reach statistical significance. In contrast, such patterns were not seen in the infected Fulani children and their chemokine levels remained unchanged upon infection compared to uninfected counterparts. Furthermore, the Fulani also had higher titres of malaria-specific IgG and IgM as well as IgG1-3 subclasses compared to the Dogon. Conclusions Taken together, this study demonstrates, in accordance with previous work

  1. Cerebral malaria protection in mice by species-specific Plasmodium coinfection is associated with reduced CC chemokine levels in the brain.

    PubMed

    Clark, C J; Phillips, R S

    2011-11-01

    Cerebral malaria is a major pathological complication of Plasmodium falciparum infection in humans. Epidemiological observations have suggested that the clinical evolution of P. falciparum infections may be influenced by the concurrent presence of another Plasmodium species. Infection of susceptible mouse strains with P. berghei ANKA (PbA) provides an experimental model of cerebral malaria which has been extensively used to identify different components of the immune system involved in cerebral malaria. This model has also been employed to investigate the influence of experimental mixed-Plasmodium-species infections on the expression of cerebral malaria; PbA-induced cerebral malaria is completely inhibited by the simultaneous presence of P. yoelii yoelii 17 X clone 1.1 parasites, and accumulation of CD8(+) T cells in the brain vasculature is abolished. We investigated whether brain levels of CD8(+) -T-cell-chemoattractant chemokines CCL3, CCL4 and CCL5 are reduced in these protected coinfected mice compared with PbA-infected mice. Coinfected mice were found to exhibit significantly reduced levels of all three chemokines on day 6 post-infection. This finding may contribute to the abolition of the accumulation of CD8(+) T cells in the brain vasculature and the prevention of the development of cerebral malaria in coinfected mice. © 2011 Blackwell Publishing Ltd.

  2. 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.

  3. Alga-Produced Malaria Transmission-Blocking Vaccine Candidate Pfs25 Formulated with a Human Use-Compatible Potent Adjuvant Induces High-Affinity Antibodies That Block Plasmodium falciparum Infection of Mosquitoes

    PubMed Central

    Patra, Kailash P.; Li, Fengwu; Carter, Darrick; Gregory, James A.; Baga, Sheyenne; Reed, Steven G.; Mayfield, Stephen P.

    2015-01-01

    A vaccine to prevent the transmission of malaria parasites from infected humans to mosquitoes is an important component for the elimination of malaria in the 21st century, yet it remains neglected as a priority of malaria vaccine development. The lead candidate for Plasmodium falciparum transmission-blocking vaccine development, Pfs25, is a sexual stage surface protein that has been produced for vaccine testing in a variety of heterologous expression systems. Any realistic malaria vaccine will need to optimize proper folding balanced against cost of production, yield, and potentially reactogenic contaminants. Here Chlamydomonas reinhardtii microalga-produced recombinant Pfs25 protein was formulated with four different human-compatible adjuvants (alum, Toll-like receptor 4 [TLR-4] agonist glucopyranosal lipid A [GLA] plus alum, squalene–oil-in-water emulsion, and GLA plus squalene–oil-in-water emulsion) and compared for their ability to induce malaria transmission-blocking antibodies. Alga-produced recombinant Pfs25 plus GLA plus squalene–oil-in-water adjuvant induced the highest titer and avidity in IgG antibodies, measured using alga-produced recombinant Pfs25 as the enzyme-linked immunosorbent assay (ELISA) antigen. These antibodies specifically reacted with the surface of P. falciparum macrogametes and zygotes and effectively prevented parasites from developing within the mosquito vector in standard membrane feeding assays. Alga-produced Pfs25 in combination with a human-compatible adjuvant composed of a TLR-4 agonist in a squalene–oil-in-water emulsion is an attractive new vaccine candidate that merits head-to-head comparison with other modalities of vaccine production and administration. PMID:25690099

  4. Alga-produced malaria transmission-blocking vaccine candidate Pfs25 formulated with a human use-compatible potent adjuvant induces high-affinity antibodies that block Plasmodium falciparum infection of mosquitoes.

    PubMed

    Patra, Kailash P; Li, Fengwu; Carter, Darrick; Gregory, James A; Baga, Sheyenne; Reed, Steven G; Mayfield, Stephen P; Vinetz, Joseph M

    2015-05-01

    A vaccine to prevent the transmission of malaria parasites from infected humans to mosquitoes is an important component for the elimination of malaria in the 21st century, yet it remains neglected as a priority of malaria vaccine development. The lead candidate for Plasmodium falciparum transmission-blocking vaccine development, Pfs25, is a sexual stage surface protein that has been produced for vaccine testing in a variety of heterologous expression systems. Any realistic malaria vaccine will need to optimize proper folding balanced against cost of production, yield, and potentially reactogenic contaminants. Here Chlamydomonas reinhardtii microalga-produced recombinant Pfs25 protein was formulated with four different human-compatible adjuvants (alum, Toll-like receptor 4 [TLR-4] agonist glucopyranosal lipid A [GLA] plus alum, squalene-oil-in-water emulsion, and GLA plus squalene-oil-in-water emulsion) and compared for their ability to induce malaria transmission-blocking antibodies. Alga-produced recombinant Pfs25 plus GLA plus squalene-oil-in-water adjuvant induced the highest titer and avidity in IgG antibodies, measured using alga-produced recombinant Pfs25 as the enzyme-linked immunosorbent assay (ELISA) antigen. These antibodies specifically reacted with the surface of P. falciparum macrogametes and zygotes and effectively prevented parasites from developing within the mosquito vector in standard membrane feeding assays. Alga-produced Pfs25 in combination with a human-compatible adjuvant composed of a TLR-4 agonist in a squalene-oil-in-water emulsion is an attractive new vaccine candidate that merits head-to-head comparison with other modalities of vaccine production and administration. Copyright © 2015, American Society for Microbiology. All Rights Reserved.

  5. Development of a pharmacovigilance safety monitoring tool for the rollout of single low-dose primaquine and artemether-lumefantrine to treat Plasmodium falciparum infections in Swaziland: a pilot study.

    PubMed

    Poirot, Eugenie; Soble, Adam; Ntshalintshali, Nyasatu; Mwandemele, Asen; Mkhonta, Nomcebo; Malambe, Calisile; Vilakati, Sibonakaliso; Pan, Sisi; Darteh, Sarah; Maphalala, Gugu; Brown, Joelle; Hwang, Jimee; Pace, Cheryl; Stergachis, Andy; Vittinghoff, Eric; Kunene, Simon; Gosling, Roland

    2016-07-22

    Countries remain reluctant to adopt the 2012 World Health Organization recommendation for single low-dose (0.25 mg/kg) primaquine (SLD PQ) for Plasmodium falciparum transmission-blocking due to concerns over drug-related haemolysis risk, especially among glucose-6-phosphate dehydrogenase-deficient (G6PDd) people, without evidence demonstrating that it can be safely deployed in their settings. Pharmacovigilance methods provide a systematic way of collecting safety data and supporting the rollout of SLD PQ. The Primaquine Roll Out Monitoring Pharmacovigilance Tool (PROMPT), comprising: (1) a standardized form to support the surveillance of possible adverse events following SLD PQ treatment; (2) a patient information card to enhance awareness of known adverse drug reactions of SLD PQ use; and (3) a database compiling recorded information, was developed and piloted. Data on patient characteristics, malaria diagnosis and treatment are collected. Blood samples are taken to measure haemoglobin (Hb) and test for G6PD deficiency. Active follow-up includes a repeat Hb measurement and adverse event monitoring on or near day 7. A 13-month prospective pilot study in two hospital facilities in Swaziland alongside the introduction of SLD PQ generated preliminary evidence on the feasibility and acceptability of PROMPT. PROMPT was well received by nurses as a simple, pragmatic approach to active surveillance of SLD PQ safety data. Of the 102 patients enrolled and administered SLD PQ, none were G6PDd. 93 (91.2 %) returned on or near day 7 for follow-up. Four (4.6 %) patients had falls in Hb ≥25 % from baseline, none of whom presented with signs or symptoms of anaemia. No patient's Hb fell below 7 g/dL and none required a blood transfusion. Of the 11 (11 %) patients who reported an adverse event over the study period, three were considered serious and included two deaths and one hospitalization; none were causally related to SLD PQ. Four non-serious adverse events were

  6. CD14(hi)CD16+ monocytes phagocytose antibody-opsonised Plasmodium falciparum infected erythrocytes more efficiently than other monocyte subsets, and require CD16 and complement to do so.

    PubMed

    Zhou, Jingling; Feng, Gaoqian; Beeson, James; Hogarth, P Mark; Rogerson, Stephen J; Yan, Yan; Jaworowski, Anthony

    2015-07-07

    With more than 600,000 deaths from malaria, mainly of children under five years old and caused by infection with Plasmodium falciparum, comes an urgent need for an effective anti-malaria vaccine. Limited details on the mechanisms of protective immunity are a barrier to vaccine development. Antibodies play an important role in immunity to malaria and monocytes are key effectors in antibody-mediated protection by phagocytosing antibody-opsonised infected erythrocytes (IE). Eliciting antibodies that enhance phagocytosis of IE is therefore an important potential component of an effective vaccine, requiring robust assays to determine the ability of elicited antibodies to stimulate this in vivo. The mechanisms by which monocytes ingest IE and the nature of the monocytes which do so are unknown. Purified trophozoite-stage P. falciparum IE were stained with ethidium bromide, opsonised with anti-erythrocyte antibodies and incubated with fresh whole blood. Phagocytosis of IE and TNF production by individual monocyte subsets was measured by flow cytometry. Ingestion of IE was confirmed by imaging flow cytometry. CD14(hi)CD16+ monocytes phagocytosed antibody-opsonised IE and produced TNF more efficiently than CD14(hi)CD16- and CD14(lo)CD16+ monocytes. Blocking experiments showed that Fcγ receptor IIIa (CD16) but not Fcγ receptor IIa (CD32a) or Fcγ receptor I (CD64) was necessary for phagocytosis. CD14(hi)CD16+ monocytes ingested antibody-opsonised IE when peripheral blood mononuclear cells were reconstituted with autologous serum but not heat-inactivated autologous serum. Antibody-opsonised IE were rapidly opsonised with complement component C3 in serum (t1/2 = 2-3 minutes) and phagocytosis of antibody-opsonised IE was inhibited in a dose-dependent manner by an inhibitor of C3 activation, compstatin. Compared to other monocyte subsets, CD14(hi)CD16+ monocytes expressed the highest levels of complement receptor 4 (CD11c) and activated complement receptor 3 (CD11b) subunits

  7. Filarial Worms Reduce Plasmodium Infectivity in Mosquitoes

    PubMed Central

    Aliota, Matthew T.; Chen, Cheng-Chen; Dagoro, Henry; Fuchs, Jeremy F.; Christensen, Bruce M.

    2011-01-01

    Background Co-occurrence of malaria and filarial worm parasites has been reported, but little is known about the interaction between filarial worm and malaria parasites with the same Anopheles vector. Herein, we present data evaluating the interaction between Wuchereria bancrofti and Anopheles punctulatus in Papua New Guinea (PNG). Our field studies in PNG demonstrated that An. punctulatus utilizes the melanization immune response as a natural mechanism of filarial worm resistance against invading W. bancrofti microfilariae. We then conducted laboratory studies utilizing the mosquitoes Armigeres subalbatus and Aedes aegypti and the parasites Brugia malayi, Brugia pahangi, Dirofilaria immitis, and Plasmodium gallinaceum to evaluate the hypothesis that immune activation and/or development by filarial worms negatively impact Plasmodium development in co-infected mosquitoes. Ar. subalbatus used in this study are natural vectors of P. gallinaceum and B. pahangi and they are naturally refractory to B. malayi (melanization-based refractoriness). Methodology/Principal Findings Mosquitoes were dissected and Plasmodium development was analyzed six days after blood feeding on either P. gallinaceum alone or after taking a bloodmeal containing both P. gallinaceum and B. malayi or a bloodmeal containing both P. gallinaceum and B. pahangi. There was a significant reduction in the prevalence and mean intensity of Plasmodium infections in two species of mosquito that had dual infections as compared to those mosquitoes that were infected with Plasmodium alone, and was independent of whether the mosquito had a melanization immune response to the filarial worm or not. However, there was no reduction in Plasmodium development when filarial worms were present in the bloodmeal (D. immitis) but midgut penetration was absent, suggesting that factors associated with penetration of the midgut by filarial worms likely are responsible for the observed reduction in malaria parasite infections

  8. 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

  9. Influence of host iron status on Plasmodium falciparum infection

    PubMed Central

    Clark, Martha A.; Goheen, Morgan M.; Cerami, Carla

    2014-01-01

    Iron deficiency affects one quarter of the world's population and causes significant morbidity, including detrimental effects on immune function and cognitive development. Accordingly, the World Health Organization (WHO) recommends routine iron supplementation in children and adults in areas with a high prevalence of iron deficiency. However, a large body of clinical and epidemiological evidence has accumulated which clearly demonstrates that host iron deficiency is protective against falciparum malaria and that host iron supplementation may increase the risk of malaria. Although many effective antimalarial treatments and preventive measures are available, malaria remains a significant public health problem, in part because the mechanisms of malaria pathogenesis remain obscured by the complexity of the relationships that exist between parasite virulence factors, host susceptibility traits, and the immune responses that modulate disease. Here we review (i) the clinical and epidemiological data that describes the relationship between host iron status and malaria infection and (ii) the current understanding of the biological basis for these clinical and epidemiological observations. PMID:24834053

  10. 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

  11. Identification of novel membrane structures in Plasmodium falciparum infected erythrocytes.

    PubMed

    Clavijo, C A; Mora, C A; Winograd, E

    1998-01-01

    Little is known about the molecular mechanisms underlying the release of merozoites from malaria infected erythrocytes. In this study membranous structures present in the culture medium at the time of merozoite release have been characterized. Biochemical and ultrastructural evidence indicate that membranous structures consist of the infected erythrocyte membrane, the parasitophorous vacuolar membrane and a residual body containing electron dense material. These are subcellular compartments expected in a structure that arises as a consequence of merozoite release from the infected cell. Ultrastructural studies show that a novel structure extends from the former parasite compartment to the surface membrane. Since these membrane modifications are detected only after merozoites have been released from the infected erythrocyte, it is proposed that they might play a role in the release of merozoites from the host cell.

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

    PubMed

    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

    2016-02-26

    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.

  13. 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

  14. Immune response to Plasmodium vivax has a potential to reduce malaria severity.

    PubMed

    Chuangchaiya, S; Jangpatarapongsa, K; Chootong, P; Sirichaisinthop, J; Sattabongkot, J; Pattanapanyasat, K; Chotivanich, K; Troye-Blomberg, M; Cui, L; Udomsangpetch, R

    2010-05-01

    Plasmodium falciparum infection causes transient immunosuppression during the parasitaemic stage. However, the immune response during simultaneous infections with both P. vivax and P. falciparum has been investigated rarely. In particular, it is not clear whether the host's immune response to malaria will be different when infected with a single or mixed malaria species. Phenotypes of T cells from mixed P. vivax-P. falciparum (PV-PF) infection were characterized by flow cytometry, and anti-malarial antibodies in the plasma were determined by an enzyme-linked immunosorbent assay. We found the percentage of CD3+delta2+-T cell receptor (TCR) T cells in the acute-mixed PV-PF infection and single P. vivax infection three times higher than in the single P. falciparum infection. This implied that P. vivax might lead to the host immune response to the production of effector T killer cells. During the parasitaemic stage, the mixed PV-PF infection had the highest number of plasma antibodies against both P. vivax and P. falciparum. Interestingly, plasma from the group of single P. vivax or P. falciparum malaria infections had both anti-P. vivax and anti-P. falciparum antibodies. In addition, antigenic cross-reactivity of P. vivax or P. falciparum resulting in antibodies against both malaria species was shown in the supernatant of lymphocyte cultures cross-stimulated with either antigen of P. vivax or P. falciparum. The role of delta2 +/- TCR T cells and the antibodies against both species during acute mixed malaria infection could have an impact on the immunity to malaria infection.

  15. Innexin AGAP001476 Is Critical for Mediating Anti-Plasmodium Responses in Anopheles Mosquitoes

    PubMed Central

    Li, Michelle W. M.; Wang, Jiuling; Zhao, Yang O.; Fikrig, Erol

    2014-01-01

    The Toll and IMD pathways are known to be induced upon Plasmodium berghei and Plasmodium falciparum infection, respectively. It is unclear how Plasmodium or other pathogens in the blood meal and their invasion of the midgut epithelium would trigger the innate immune responses in immune cells, in particular hemocytes. Gap junctions, which can mediate both cell-to-cell and cell-to-extracellular communication, may participate in this signal transduction. This study examined whether innexins, gap junction proteins in insects, are involved in anti-Plasmodium responses in Anopheles gambiae. Inhibitor studies using carbenoxolone indicated that blocking innexons resulted in an increase in Plasmodium oocyst number and infection prevalence. This was accompanied by a decline in TEP1 levels in carbenoxolone-treated mosquitoes. Innexin AGAP001476 mRNA levels in midguts were induced during Plasmodium infection and a knockdown of AGAP001476, but not AGAP006241, caused an induction in oocyst number. Silencing AGAP001476 caused a concurrent increase in vitellogenin levels, a TEP1 inhibitor, in addition to a reduced level of TEP1-LRIM1-APL1C complex in hemolymph. Both vitellogenin and TEP1 are regulated by Cactus under the Toll pathway. Simultaneous knockdown of cactus and AGAP001476 failed to reverse the near refractoriness induced by the knockdown of cactus, suggesting that the AGAP001476-mediated anti-Plasmodium response is Cactus-dependent. These data demonstrate a critical role for innexin AGAP001476 in mediating innate immune responses against Plasmodium through Toll pathway in mosquitoes. PMID:25035430

  16. Innexin AGAP001476 is critical for mediating anti-Plasmodium responses in Anopheles mosquitoes.

    PubMed

    Li, Michelle W M; Wang, Jiuling; Zhao, Yang O; Fikrig, Erol

    2014-09-05

    The Toll and IMD pathways are known to be induced upon Plasmodium berghei and Plasmodium falciparum infection, respectively. It is unclear how Plasmodium or other pathogens in the blood meal and their invasion of the midgut epithelium would trigger the innate immune responses in immune cells, in particular hemocytes. Gap junctions, which can mediate both cell-to-cell and cell-to-extracellular communication, may participate in this signal transduction. This study examined whether innexins, gap junction proteins in insects, are involved in anti-Plasmodium responses in Anopheles gambiae. Inhibitor studies using carbenoxolone indicated that blocking innexons resulted in an increase in Plasmodium oocyst number and infection prevalence. This was accompanied by a decline in TEP1 levels in carbenoxolone-treated mosquitoes. Innexin AGAP001476 mRNA levels in midguts were induced during Plasmodium infection and a knockdown of AGAP001476, but not AGAP006241, caused an induction in oocyst number. Silencing AGAP001476 caused a concurrent increase in vitellogenin levels, a TEP1 inhibitor, in addition to a reduced level of TEP1-LRIM1-APL1C complex in hemolymph. Both vitellogenin and TEP1 are regulated by Cactus under the Toll pathway. Simultaneous knockdown of cactus and AGAP001476 failed to reverse the near refractoriness induced by the knockdown of cactus, suggesting that the AGAP001476-mediated anti-Plasmodium response is Cactus-dependent. These data demonstrate a critical role for innexin AGAP001476 in mediating innate immune responses against Plasmodium through Toll pathway in mosquitoes.

  17. Reduced erythrocyte deformability associated with hypoargininemia during Plasmodium falciparum malaria.

    PubMed

    Rey, Juliana; Buffet, Pierre A; Ciceron, Liliane; Milon, Geneviève; Mercereau-Puijalon, Odile; Safeukui, Innocent

    2014-01-20

    The mechanisms underlying reduced red blood cell (RBC) deformability during Plasmodium falciparum (Pf) malaria remain poorly understood. Here, we explore the possible involvement of the L-arginine and nitric oxide (NO) pathway on RBC deformability in Pf-infected patients and parasite cultures. RBC deformability was reduced during the acute attack (day0) and returned to normal values upon convalescence (day28). Day0 values correlated with plasma L-arginine levels (r = 0.69; p = 0.01) and weakly with parasitemia (r = -0.38; p = 0.006). In vitro, day0 patient's plasma incubated with ring-stage cultures at 41°C reduced RBC deformability, and this effect correlated strongly with plasma L-arginine levels (r = 0.89; p < 0.0001). Moreover, addition of exogenous L-arginine to the cultures increased deformability of both Pf-free and trophozoite-harboring RBCs. NO synthase activity, evidenced in Pf-infected RBCs, induced L-arginine-dependent NO production. These data show that hypoargininemia during P. falciparum malaria may altogether impair NO production and reduce RBC deformability, particularly at febrile temperature.

  18. In vitro alterations do not reflect a requirement for host cell cycle progression during Plasmodium liver stage infection.

    PubMed

    Hanson, Kirsten K; March, Sandra; Ng, Shengyong; Bhatia, Sangeeta N; Mota, Maria M

    2015-01-01

    Prior to invading nonreplicative erythrocytes, Plasmodium parasites undergo their first obligate step in the mammalian host inside hepatocytes, where each sporozoite replicates to generate thousands of merozoites. While normally quiescent, hepatocytes retain proliferative capacity and can readily reenter the cell cycle in response to diverse stimuli. Many intracellular pathogens, including protozoan parasites, manipulate the cell cycle progression of their host cells for their own benefit, but it is not known whether the hepatocyte cell cycle plays a role during Plasmodium liver stage infection. Here, we show that Plasmodium parasites can be observed in mitotic hepatoma cells throughout liver stage development, where they initially reduce the likelihood of mitosis and ultimately lead to significant acquisition of a binucleate phenotype. However, hepatoma cells pharmacologically arrested in S phase still support robust and complete Plasmodium liver stage development, which thus does not require cell cycle progression in the infected cell in vitro. Furthermore, murine hepatocytes remain quiescent throughout in vivo infection with either Plasmodium berghei or Plasmodium yoelii, as do Plasmodium falciparum-infected primary human hepatocytes, demonstrating that the rapid and prodigious growth of liver stage parasites is accomplished independent of host hepatocyte cell cycle progression during natural infection.

  19. Plasmodium falciparum malaria.

    PubMed

    Shetty, A K; Steele, R W

    1999-01-01

    A 13-year-old adolescent daughter of a missionary presented with fever and jaundice 1 week after returning from Africa. Examination of peripheral blood film revealed the diagnosis of Plasmodium falciparum infection. Therapy with oral quinine and doxycycline was curative. Diagnosis requires a travel history and a high index of suspicion. Because of the frequency of international travel, United States physicians need to be familiar with the presentation and management of imported P falciparum. Preparation for such travel must include careful counseling and optimal use of chemoprophylaxis.

  20. 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

  1. 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

  2. Reduced polymorphism in the Kelch propeller domain in Plasmodium vivax isolates from Cambodia.

    PubMed

    Popovici, Jean; Kao, Sokheng; Eal, Leanghor; Bin, Sophalai; Kim, Saorin; Ménard, Didier

    2015-01-01

    Polymorphism in the ortholog gene of the Plasmodium falciparum K13 gene was investigated in Plasmodium vivax isolates collected in Cambodia. All of them were Sal-1 wild-type alleles except two (2/284, 0.7%), and P. vivax K12 polymorphism was reduced compared to that of the P. falciparum K13 gene. Both mutant allele isolates had the same nonsynonymous mutation at codon 552 (V552I) and were from Ratanak Kiri province. These preliminary data should encourage additional studies for associating artemisinin or chloroquine resistance and K12 polymorphism.

  3. Reduced Polymorphism in the Kelch Propeller Domain in Plasmodium vivax Isolates from Cambodia

    PubMed Central

    Popovici, Jean; Kao, Sokheng; Eal, Leanghor; Bin, Sophalai; Kim, Saorin

    2014-01-01

    Polymorphism in the ortholog gene of the Plasmodium falciparum K13 gene was investigated in Plasmodium vivax isolates collected in Cambodia. All of them were Sal-1 wild-type alleles except two (2/284, 0.7%), and P. vivax K12 polymorphism was reduced compared to that of the P. falciparum K13 gene. Both mutant allele isolates had the same nonsynonymous mutation at codon 552 (V552I) and were from Ratanak Kiri province. These preliminary data should encourage additional studies for associating artemisinin or chloroquine resistance and K12 polymorphism. PMID:25385109

  4. The pathogenesis of Plasmodium falciparum malaria in humans: insights from splenic physiology

    PubMed Central

    Safeukui, Innocent; Deplaine, Guillaume; Brousse, Valentine; Prendki, Virginie; Thellier, Marc; Turner, Gareth D.; Mercereau-Puijalon, Odile

    2011-01-01

    Clinical manifestations of Plasmodium falciparum infection are induced by the asexual stages of the parasite that develop inside red blood cells (RBCs). Because splenic microcirculatory beds filter out altered RBCs, the spleen can innately clear subpopulations of infected or uninfected RBC modified during falciparum malaria. The spleen appears more protective against severe manifestations of malaria in naïve than in immune subjects. The spleen-specific pitting function accounts for a large fraction of parasite clearance in artemisinin-treated patients. RBC loss contributes to malarial anemia, a clinical form associated with subacute progression, frequent splenomegaly, and relatively low parasitemia. Stringent splenic clearance of ring-infected RBCs and uninfected, but parasite-altered, RBCs, may altogether exacerbate anemia and reduce the risks of severe complications associated with high parasite loads, such as cerebral malaria. The age of the patient directly influences the risk of severe manifestations. We hypothesize that coevolution resulting in increased splenic clearance of P. falciparum–altered RBCs in children favors the survival of the host and, ultimately, sustained parasite transmission. This analysis of the RBC–spleen dynamic interactions during P falciparum infection reflects both data and hypotheses, and provides a framework on which a more complete immunologic understanding of malaria pathogenesis may be elaborated. PMID:20852127

  5. Plasmodium falciparum picks (on) EPCR

    PubMed Central

    Mosnier, Laurent O.; Fairhurst, Rick M.

    2014-01-01

    Of all the outcomes of Plasmodium falciparum infection, the coma of cerebral malaria (CM) is particularly deadly. Malariologists have long wondered how some patients develop this organ-specific syndrome. Data from two recent publications support a novel mechanism of CM pathogenesis in which infected erythrocytes (IEs) express specific virulence proteins that mediate IE binding to the endothelial protein C receptor (EPCR). Malaria-associated depletion of EPCR, with subsequent impairment of the protein C system promotes a proinflammatory, procoagulant state in brain microvessels. PMID:24246501

  6. 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

  7. 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

  8. Anopheles Midgut FREP1 Mediates Plasmodium Invasion*

    PubMed Central

    Zhang, Genwei; Niu, Guodong; Franca, Caio M.; Dong, Yuemei; Wang, Xiaohong; Butler, Noah S.; Dimopoulos, George; Li, Jun

    2015-01-01

    Malaria transmission depends on sexual stage Plasmodium parasites successfully invading Anopheline mosquito midguts following a blood meal. However, the molecular mechanisms of Plasmodium invasion of mosquito midguts have not been fully elucidated. Previously, we showed that genetic polymorphisms in the fibrinogen-related protein 1 (FREP1) gene are significantly associated with Plasmodium falciparum infection in Anopheles gambiae, and FREP1 is important for Plasmodium berghei infection of mosquitoes. Here we identify that the FREP1 protein is secreted from the mosquito midgut epithelium and integrated as tetramers into the peritrophic matrix, a chitinous matrix formed inside the midgut lumen after a blood meal feeding. Moreover, we show that the FREP1 can directly bind Plasmodia sexual stage gametocytes and ookinetes. Notably, ablating FREP1 expression or targeting FREP1 with antibodies significantly decreases P. falciparum infection in mosquito midguts. Our data support that the mosquito-expressed FREP1 mediates mosquito midgut invasion by multiple species of Plasmodium parasites via anchoring ookinetes to the peritrophic matrix and enabling parasites to penetrate the peritrophic matrix and the epithelium. Thus, targeting FREP1 can limit malaria transmission. PMID:25991725

  9. [Gametocyte carriage in asymptomatic Plasmodium falciparum infections in Haiti (2010-2013)].

    PubMed

    Raccurt, C P; Brasseur, P; Cicéron, M; Existe, A; Lemoine, F; Boncy, J

    2015-02-01

    A survey conducted from May 2010 to October 2013 in five from ten departments of Haiti among 5,342 persons aged from 1 to 107 years showed a gametocytic rate = 3.2%. However, it varies greatly from one Department to another, ranging from 0.5% in Grande Anse Department to 5.9% in Southeast Department. Malaria is present in Haiti in heterogeneous coastal foci. Gametocytes occur at all ages, but two times most often in male under 20 years. Entomological studies in Haiti are needed to better characterize the relationships between man and the vector Anopheles albimanus, adapting the fight more effectively.

  10. p-Aminobenzoic acid transport by normal and Plasmodium falciparum-infected erythrocytes.

    PubMed

    Zhang, Y; Merali, S; Meshnick, S R

    1992-06-01

    De novo folate biosynthesis is required for the growth of malarial parasites and is inhibited by several important antimalarial agents. We show here that exogenous p-aminobenzoic acid (pABA) can be utilized by malaria parasites to synthesize folates. The transport of pABA into parasite infected red cells was therefore characterized. Normal red cells transport pABA in a saturable and energy-dependent manner, with a dissociation constant of 83 nM. pABA transport in parasite-infected red cells may use the same mechanism, as demonstrated by similarities in time course, concentration-response, and dissociation constant (111 nM). The transport capacity of red cells is temperature-, energy- and pH-dependent. It is inhibited by the proton ionophore, carbonylcyanide m-chlorophenylhydrazone (CCCP), but not by the sodium ionophores nigericin and monensin. p-Aminosalicylic acid (PAS) inhibits pABA transport competitively, with a inhibition constant of 378 nM. Phloritin, flufanamic acid, and 4,4'-diisothiocyanatostilbene-2,2'-disulfonic acid (DITS), which are inhibitors of the anion transporter (band 3), and oxalic acid, a substrate of this transporter, partially inhibit pABA transport into both normal and infected red cells. Interestingly, in both normal and infected red cells, the inhibitory effects of PAS and the anion transport inhibitors are additive, suggesting the involvement of 2 independent mechanisms.

  11. Acalculous Cholecystitis in a Pediatric Patient with Plasmodium falciparum Infection: A Case Report and Literature Review.

    PubMed

    Aguilera-Alonso, David; Medina, Eva María López; Del Rosal, Teresa; Arrieta, Julián Villota; Escosa-García, Luis; Hortelano, Milagros García

    2017-08-02

    Malaria has been associated with acute acalculous cholecystitis, a very uncommon complication in children. We present a 5-year-old girl, originally from Equatorial-Guinea, diagnosed with severe malaria with acute kidney injury, thrombocytopenia and acute acalculous cholecystitis. She was treated with intravenous quinine and clindamycin, plus cefotaxime and metronidazole with a full resolution without surgery.

  12. Mosquito biting activity on humans & detection of Plasmodium falciparum infection in Anopheles stephensi in Goa, India

    PubMed Central

    Korgaonkar, Nandini S.; Kumar, Ashwani; Yadav, Rajpal S.; Kabadi, Dipak; Dash, Aditya P.

    2012-01-01

    Background & objectives: Knowledge of the bionomics of mosquitoes, especially of disease vectors, is essential to plan appropriate vector avoidance and control strategies. Information on biting activity of vectors during the night hours in different seasons is important for choosing personal protection measures. This study was carried out to find out the composition of mosquito fauna biting on humans and seasonal biting trends in Goa, India. Methods: Biting activities of all mosquitoes including vectors were studied from 1800 to 0600 h during 85 nights using human volunteers in 14 different localities of three distinct ecotypes in Goa. Seasonal biting trends of vector species were analysed and compared. Seasonal biting periodicity during different phases of night was also studied using William's mean. Results: A total of 4,191 mosquitoes of five genera and 23 species were collected. Ten species belonged to Anopheles, eight to Culex, three to Aedes and one each to Mansonia and Armigeres. Eleven vector species had human hosts, including malaria vectors Anopheles stephensi (1.3%), An. fluviatilis (1.8%), and An. culicifacies (0.76%); filariasis vectors Culex quinquefasciatus (40.8%) and Mansonia uniformis (1.8%); Japanese encephalitis vectors Cx. tritaeniorhynchus (17.4%), Cx. vishnui (7.7%), Cx. pseudovishnui (0.1%), and Cx. gelidus (2.4%); and dengue and chikungunya vectors Aedes albopictus (0.9%) and Ae. aegypti (0.6%). Two An. stephensi of the total 831 female anophelines, were found positive for P. falciparum sporozoites. The entomological inoculation rate (EIR) of P. falciparum was 18.1 and 2.35 for Panaji city and Goa, respectively. Interpretation & conclusions: Most of the mosquito vector species were collected in all seasons and throughout the scotophase. Biting rates of different vector species differed during different phases of night and seasons. Personal protection methods could be used to stop vector-host contact. PMID:22382193

  13. Associations between Red Cell Polymorphisms and Plasmodium falciparum Infection in the Middle Belt of Ghana

    PubMed Central

    Amoako, Nicholas; Asante, Kwaku Poku; Adjei, George; Awandare, Gordon A.; Bimi, Langbong; Owusu-Agyei, Seth

    2014-01-01

    Background Red blood cell (RBC) polymorphisms are common in malaria endemic regions and are known to protect against severe forms of the disease. Therefore, it is important to screen for these polymorphisms in drugs or vaccines efficacy trials. This study was undertaken to evaluate associations between clinical malaria and RBC polymorphisms to assess biological interactions that may be necessary for consideration when designing clinical trials. Method In a cross-sectional study of 341 febrile children less than five years of age, associations between clinical malaria and common RBC polymorphisms including the sickle cell gene and G6PD deficiency was evaluated between November 2008 and June 2009 in the middle belt of Ghana, Kintampo. G6PD deficiency was determined by quantitative methods whiles haemoglobin variants were determined by haemoglobin titan gel electrophoresis. Blood smears were stained with Giemsa and parasite densities were determined microscopically. Results The prevalence of clinical malarial among the enrolled children was 31.9%. The frequency of G6PD deficiency was 19.0% and that for the haemoglobin variants were 74.7%, 14.7%, 9.1%, 0.9% respectively for HbAA, HbAC, HbAS and HbSS. In Multivariate regression analysis, children with the HbAS genotype had 79% lower risk of malaria infection compared to those with the HbAA genotypes (OR = 0.21, 95% CI: 0.06–0.73, p = 0.01). HbAC genotype was not significantly associated with malaria infection relative to the HbAA genotype (OR = 0.70, 95% CI: 0.35–1.42, p = 0.33). G6PD deficient subgroup had a marginally increased risk of malaria infection compared to the G6PD normal subgroup (OR = 1.76, 95% CI: 0.98–3.16, p = 0.06). Conclusion These results confirm previous findings showing a protective effect of sickle cell trait on clinical malaria infection. However, G6PD deficiency was associated with a marginal increase in susceptibility to clinical malaria compared to children without G6PD deficiency. PMID:25470251

  14. 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

  15. Plasmodium falciparum and helminth coinfection in a semi urban population of pregnant women in Uganda.

    PubMed

    Hillier, Stephen D; Booth, Mark; Muhangi, Lawrence; Nkurunziza, Peter; Khihembo, Macklyn; Kakande, Muhammad; Sewankambo, Moses; Kizindo, Robert; Kizza, Moses; Muwanga, Moses; Elliott, Alison M

    2008-09-15

    Helminth infections and malaria are widespread in the tropics. Recent studies suggest helminth infections may increase susceptibility to Plasmodium falciparum infection. If confirmed, this increased susceptibility could be particularly important during pregnancy-induced immunosuppression. To evaluate the geographical distribution of P. falciparum-helminth coinfection and the associations between P. falciparum infection and infection with various parasite species in pregnant women in Entebbe, Uganda. A cross-sectional study was conducted at baseline during a trial of antihelminthic drugs during pregnancy. Helminth and P. falciparum infections were quantified in 2,507 asymptomatic women. Subjects' socioeconomic and demographic characteristics and geographical details were recorded. Hookworm and Mansonella perstans infections were associated with P. falciparum infection, but the effect of hookworm infection was seen only in the absence of M. perstans infection. The odds ratio [OR] for P. falciparum infection, adjusted for age, tribe, socioeconomic status, HIV infection status, and location was as follows: for individuals infected with hookworm but not M. perstans, 1.53 (95% confidence interval [CI], 1.09-2.14); for individuals infected with M. perstans but not hookworm, 2.33 (95% CI, 1.47-3.69); for individuals infected with both hookworm and M. perstans, 1.85 (CI, 1.24-2.76). No association was observed between infection with Schistosoma mansoni, Trichuris, or Strongyloides species and P. falciparum infection. Hookworm-P. falciparum coinfection and M. perstans-P. falciparum coinfection among pregnant women in Entebbe is more common than would be expected by chance. Further studies are needed to elucidate the mechanism of this association. A helminth-induced increase in susceptibility to P. falciparum could have important consequences for pregnancy outcome and responses to P. falciparum infection in infancy.

  16. 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.

  17. Clearance of Asymptomatic P. falciparum Infections Interacts with the Number of Clones to Predict the Risk of Subsequent Malaria in Kenyan Children

    PubMed Central

    Liljander, Anne; Bejon, Philip; Mwacharo, Jedidah; Kai, Oscar; Ogada, Edna; Peshu, Norbert; Marsh, Kevin; Färnert, Anna

    2011-01-01

    Background Protective immunity to malaria is acquired after repeated infections in endemic areas. Asymptomatic multiclonal P. falciparum infections are common and may predict host protection. Here, we have investigated the effect of clearing asymptomatic infections on the risk of clinical malaria. Methods Malaria episodes were continuously monitored in 405 children (1–6 years) in an area of moderate transmission, coastal Kenya. Blood samples collected on four occasions were assessed by genotyping the polymorphic P. falciparum merozoite surface protein 2 using fluorescent PCR and capillary electrophoresis. Following the second survey, asymptomatic infections were cleared with a full course of dihydroartemisinin. Results Children who were parasite negative by PCR had a lower risk of subsequent malaria regardless of whether treatment had been given. Children with ≥2 clones had a reduced risk of febrile malaria compared with 1 clone after clearance of asymptomatic infections, but not if asymptomatic infections were not cleared. Multiclonal infection was associated with an increased risk of re-infection after drug treatment. However, among the children who were re-infected, multiclonal infections were associated with a shift from clinical malaria to asymptomatic parasitaemia. Conclusion The number of clones was associated with exposure as well as blood stage immunity. These effects were distinguished by clearing asymptomatic infection with anti-malarials. Exposure to multiple P. falciparum infections is associated with protective immunity, but there appears to be an additional effect in untreated multiclonal infections that offsets this protective effect. PMID:21383984

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

    PubMed

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

    2016-07-19

    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-1(R) 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.

  19. 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

  20. 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

  1. Atomic force microscopy of Plasmodium-infected red blood cells: detecting and localizing single molecular recognition events.

    PubMed

    Li, Ang; Rénia, Laurent; Lim, Chwee Teck; Russell, Bruce

    2013-01-01

    Atomic Force Microscopy (AFM) is a powerful tool for exploring the interaction between ligands and receptors, as well as their exact locations on the red cell surface. Here we discuss current and future applications for AFM based single-molecule force spectroscopy to study adhesion of Plasmodium-infected red blood cells. A protocol is provided for simultaneous topography and recognition imaging of the surface of Plasmodium falciparum-infected cells using CD36 functionalized tips.

  2. 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

  3. Plasmodium falciparum Nucleosomes Exhibit Reduced Stability and Lost Sequence Dependent Nucleosome Positioning

    PubMed Central

    Silberhorn, Elisabeth; Schwartz, Uwe; Symelka, Anne; de Koning-Ward, Tania; Längst, Gernot

    2016-01-01

    The packaging and organization of genomic DNA into chromatin represents an additional regulatory layer of gene expression, with specific nucleosome positions that restrict the accessibility of regulatory DNA elements. The mechanisms that position nucleosomes in vivo are thought to depend on the biophysical properties of the histones, sequence patterns, like phased di-nucleotide repeats and the architecture of the histone octamer that folds DNA in 1.65 tight turns. Comparative studies of human and P. falciparum histones reveal that the latter have a strongly reduced ability to recognize internal sequence dependent nucleosome positioning signals. In contrast, the nucleosomes are positioned by AT-repeat sequences flanking nucleosomes in vivo and in vitro. Further, the strong sequence variations in the plasmodium histones, compared to other mammalian histones, do not present adaptations to its AT-rich genome. Human and parasite histones bind with higher affinity to GC-rich DNA and with lower affinity to AT-rich DNA. However, the plasmodium nucleosomes are overall less stable, with increased temperature induced mobility, decreased salt stability of the histones H2A and H2B and considerable reduced binding affinity to GC-rich DNA, as compared with the human nucleosomes. In addition, we show that plasmodium histone octamers form the shortest known nucleosome repeat length (155bp) in vitro and in vivo. Our data suggest that the biochemical properties of the parasite histones are distinct from the typical characteristics of other eukaryotic histones and these properties reflect the increased accessibility of the P. falciparum genome. PMID:28033404

  4. Plasmodium falciparum Nucleosomes Exhibit Reduced Stability and Lost Sequence Dependent Nucleosome Positioning.

    PubMed

    Silberhorn, Elisabeth; Schwartz, Uwe; Löffler, Patrick; Schmitz, Samuel; Symelka, Anne; de Koning-Ward, Tania; Merkl, Rainer; Längst, Gernot

    2016-12-01

    The packaging and organization of genomic DNA into chromatin represents an additional regulatory layer of gene expression, with specific nucleosome positions that restrict the accessibility of regulatory DNA elements. The mechanisms that position nucleosomes in vivo are thought to depend on the biophysical properties of the histones, sequence patterns, like phased di-nucleotide repeats and the architecture of the histone octamer that folds DNA in 1.65 tight turns. Comparative studies of human and P. falciparum histones reveal that the latter have a strongly reduced ability to recognize internal sequence dependent nucleosome positioning signals. In contrast, the nucleosomes are positioned by AT-repeat sequences flanking nucleosomes in vivo and in vitro. Further, the strong sequence variations in the plasmodium histones, compared to other mammalian histones, do not present adaptations to its AT-rich genome. Human and parasite histones bind with higher affinity to GC-rich DNA and with lower affinity to AT-rich DNA. However, the plasmodium nucleosomes are overall less stable, with increased temperature induced mobility, decreased salt stability of the histones H2A and H2B and considerable reduced binding affinity to GC-rich DNA, as compared with the human nucleosomes. In addition, we show that plasmodium histone octamers form the shortest known nucleosome repeat length (155bp) in vitro and in vivo. Our data suggest that the biochemical properties of the parasite histones are distinct from the typical characteristics of other eukaryotic histones and these properties reflect the increased accessibility of the P. falciparum genome.

  5. Markers of sulfadoxine-pyrimethamine-resistant Plasmodium falciparum in placenta and circulation of pregnant women.

    PubMed

    Mockenhaupt, Frank P; Bedu-Addo, George; Junge, Claudia; Hommerich, Lena; Eggelte, Teunis A; Bienzle, Ulrich

    2007-01-01

    Placental sequestration of Plasmodium falciparum in pregnancy may impair the usefulness of molecular markers of sulfadoxine-pyrimethamine resistance. In 300 infected, delivering women, the concordance of PCR-restriction fragment length polymorphism-derived parasite resistance alleles in matched samples from placenta and circulation was 83 to 98%. Sulfadoxine-pyrimethamine resistance typing in peripheral blood is reasonably representative of P. falciparum infecting pregnant women.

  6. Bacteria- and IMD Pathway-Independent Immune Defenses against Plasmodium falciparum in Anopheles gambiae

    PubMed Central

    Blumberg, Benjamin J.; Trop, Stefanie; Das, Suchismita; Dimopoulos, George

    2013-01-01

    The mosquito Anopheles gambiae uses its innate immune system to control bacterial and Plasmodium infection of its midgut tissue. The activation of potent IMD pathway-mediated anti-Plasmodium falciparum defenses is dependent on the presence of the midgut microbiota, which activate this defense system upon parasite infection through a peptidoglycan recognition protein, PGRPLC. We employed transcriptomic and reverse genetic analyses to compare the P. falciparum infection-responsive transcriptomes of septic and aseptic mosquitoes and to determine whether bacteria-independent anti-Plasmodium defenses exist. Antibiotic treated aseptic mosquitoes mounted molecular immune responses representing a variety of immune functions upon P. falciparum infection. Among other immune factors, our analysis uncovered a serine protease inhibitor (SRPN7) and Clip-domain serine protease (CLIPC2) that were transcriptionally induced in the midgut upon P. falciparum infection, independent of bacteria. We also showed that SRPN7 negatively and CLIPC2 positively regulate the anti-Plasmodium defense, independently of the midgut-associated bacteria. Co-silencing assays suggested that these two genes may function together in a signaling cascade. Neither gene was regulated, nor modulated, by infection with the rodent malaria parasite Plasmodium berghei, suggesting that SRPN7 and CLIPC2 are components of a defense system with preferential activity towards P. falciparum. Further analysis using RNA interference determined that these genes do not regulate the anti-Plasmodium defense mediated by the IMD pathway, and both factors act as agonists of the endogenous midgut microbiota, further demonstrating the lack of functional relatedness between these genes and the bacteria-dependent activation of the IMD pathway. This is the first study confirming the existence of a bacteria-independent, anti-P. falciparum defense. Further exploration of this anti-Plasmodium defense will help clarify determinants of

  7. Gametocyte Dynamics and the Role of Drugs in Reducing the Transmission Potential of Plasmodium vivax

    PubMed Central

    Douglas, Nicholas M.; Simpson, Julie A.; Phyo, Aung Pyae; Siswantoro, Hadjar; Hasugian, Armedy R.; Kenangalem, Enny; Poespoprodjo, Jeanne Rini; Singhasivanon, Pratap; Anstey, Nicholas M.; White, Nicholas J.; Tjitra, Emiliana; Nosten, Francois; Price, Ric N.

    2013-01-01

    Background. Designing interventions that will reduce transmission of vivax malaria requires knowledge of Plasmodium vivax gametocyte dynamics. Methods. We analyzed data from a randomized controlled trial in northwestern Thailand and 2 trials in Papua, Indonesia, to identify and compare risk factors for vivax gametocytemia at enrollment and following treatment. Results. A total of 492 patients with P. vivax infections from Thailand and 476 patients (162 with concurrent falciparum parasitemia) from Indonesia were evaluable. Also, 84.3% (415/492) and 66.6% (209/314) of patients with monoinfection were gametocytemic at enrollment, respectively. The ratio of gametocytemia to asexual parasitemia did not differ between acute and recurrent infections (P = .48 in Thailand, P = .08 in Indonesia). High asexual parasitemia was associated with an increased risk of gametocytemia during follow-up in both locations. In Thailand, the cumulative incidence of gametocytemia between day 7 and day 42 following dihydroartemisinin + piperaquine (DHA + PIP) was 6.92% vs 29.1% following chloroquine (P < .001). In Indonesia, the incidence of gametocytemia was 33.6% following artesunate + amodiaquine (AS + AQ), 7.42% following artemether + lumefantrine, and 6.80% following DHA + PIP (P < .001 for DHA + PIP vs AS + AQ). Conclusions. P. vivax gametocyte carriage mirrors asexual-stage infection. Prevention of relapses, particularly in those with high asexual parasitemia, is likely the most important strategy for interrupting P. vivax transmission. PMID:23766527

  8. Reduced artemisinin susceptibility of Plasmodium falciparum ring stages in western Cambodia.

    PubMed

    Witkowski, Benoit; 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; Menard, Didier

    2013-02-01

    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.

  9. 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

  10. Construction of a human functional single-chain variable fragment (scFv) antibody recognizing the malaria parasite Plasmodium falciparum.

    PubMed

    Wajanarogana, Sumet; Prasomrothanakul, Teerawat; Udomsangpetch, Rachanee; Tungpradabkul, Sumalee

    2006-04-01

    Falciparum malaria is one of the most deadly and profound human health problems around the tropical world. Antimalarial drugs are now considered to be a powerful treatment; however, there are drugs currently being used that are resistant to Plasmodium falciparum parasites spreading in different parts of the world. Although the protective immune response against intraerythrocytic stages of the falciparum malaria parasite is still not fully understood, immune antibodies have been shown to be associated with reduced parasite prevalence. Therefore antibodies of the right specificity present in adequate concentrations and affinity are reasonably effective in providing protection. In the present study, VH (variable domain of heavy chain) and VL (variable domain of light chain) were isolated from human blood lymphocytes of P. falciparum in one person who had high serum titre to RESA (ring-infected erythrocyte surface antigen). Equal amounts of VH and VL were assembled together with universal linker (G4S)3 to generate scFvs (single-chain variable fragments). The scFv antibodies were expressed with a phage system for the selection process. Exclusively, an expressed scFv against asynchronous culture of P. falciparum-infected erythrocytes was selected and characterized. Sequence analysis of selected scFv revealed that this clone could be classified into a VH family-derived germline gene (VH1) and Vkappa family segment (Vkappa1). Using an indirect immunofluorescence assay, we could show that soluble expressed scFv reacted with falciparum-infected erythrocytes. The results encourage the further study of scFvs for development as a potential immunotherapeutic agent.

  11. 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

  12. Characterization of blood dendritic and regulatory T cells in asymptomatic adults with sub-microscopic Plasmodium falciparum or Plasmodium vivax infection.

    PubMed

    Kho, Steven; Marfurt, Jutta; Handayuni, Irene; Pava, Zuleima; 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

    2016-06-21

    Plasmodium falciparum and Plasmodium vivax infections compromise dendritic cell (DC) function and expand regulatory T (Treg) cells in both clinical disease (malaria) and experimental human sub-microscopic infection. Conversely, in asymptomatic microscopy-positive (patent) P. falciparum or P. vivax infection in endemic areas, blood DC increase or retain HLA-DR expression and Treg cells exhibit reduced activation, suggesting that DC and Treg cells contribute to the control of patent asymptomatic infection. The effect of sub-microscopic (sub-patent) asymptomatic Plasmodium infection on DC and Treg cells in malaria-endemic area residents remains unclear. In a cross-sectional household survey conducted in Papua, Indonesia, 162 asymptomatic adults were prospectively evaluated for DC and Treg cells using field-based flow cytometry. Of these, 161 individuals (99 %) were assessed retrospectively by polymerase chain reaction (PCR), 19 of whom had sub-microscopic infection with P. falciparum and 15 with sub-microscopic P. vivax infection. Flow cytometric data were re-analysed after re-grouping asymptomatic individuals according to PCR results into negative controls, sub-microscopic and microscopic parasitaemia to examine DC and Treg cell phenotype in sub-microscopic infection. Asymptomatic adults with sub-microscopic P. falciparum or P. vivax infection had DC HLA-DR expression and Treg cell activation comparable to PCR-negative controls. Sub-microscopic P. falciparum infection was associated with lower peripheral CD4(+) T cells and lymphocytes, however sub-microscopic Plasmodium infection had no apparent effect on DC sub-set number or Treg cell frequency. In contrast to the impairment of DC maturation/function and the activation of Treg cells seen with sub-microscopic parasitaemia in primary experimental human Plasmodium infection, no phenotypic evidence of dysregulation of DC and Treg cells was observed in asymptomatic sub-microscopic Plasmodium infection in Indonesian

  13. 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

  14. Clinical Predictors of Severe Malarial Anaemia in a Holoendemic Plasmodium falciparum Transmission Area

    PubMed Central

    Novelli, Enrico M.; Hittner, James B.; Davenport, Gregory C.; Ouma, Collins; Were, Tom; Obaro, Stephen; Kaplan, Sandra; Ong’echa, John M.; Perkins, Douglas J.

    2011-01-01

    SUMMARY Severe malarial anaemia (SMA) is a common complication of Plasmodium falciparum infections, resulting in mortality rates that may exceed 30% in paediatric populations residing in holoendemic transmission areas. One strategy for reducing the morbidity and mortality associated with SMA is to identify clinical predictors that can be readily recognized by caregivers for prompt therapeutic interventions. To determine clinical predictors of SMA, Kenyan children (3-36 mos., n=671) presenting with acute illness at a rural hospital in Siaya District were recruited. Demographic, clinical, laboratory and haematological parameters were measured upon enrolment. Since HIV-1 and bacteraemia promote reduced haemoglobin (Hb) concentrations, children with these infections were excluded from the analyses. Children with P. falciparum mono-infections (n=355) were stratified into three groups: uncomplicated malaria (Hb≥11.0 g/dL); non-SMA (6.0≤Hb<10.9), and SMA (Hb<6.0 g/dL). SMA was characterized by a younger age, monocytosis, thrombocytopaenia, reticulocytosis, reduced erythropoiesis, elevated pigment-containing monocytes (PCM), respiratory distress, conjunctival and palmar pallor, splenomegaly, signs of malnutrition, and protracted fever and emesis. Logistic regression analysis demonstrated that age, reticulocyte count, presence of PCM and conjunctival and palmar pallor were significant predictors of SMA. Recognition of these clinical signs in children residing in resource-poor settings may help guide the identification and management of SMA. PMID:20408849

  15. The Use of Mosquito Nets and the Prevalence of Plasmodium falciparum Infection in Rural South Central Somalia

    PubMed Central

    Noor, Abdisalan M.; Moloney, Grainne; Borle, Mohamed; Fegan, Greg W.; Shewchuk, Tanya; Snow, Robert W.

    2008-01-01

    Background There have been resurgent efforts in Africa to estimate the public health impact of malaria control interventions such as insecticide treated nets (ITNs) following substantial investments in scaling-up coverage in the last five years. Little is known, however, on the effectiveness of ITN in areas of Africa that support low transmission. This hinders the accurate estimation of impact of ITN use on disease burden and its cost-effectiveness in low transmission settings. Methods and Principal Findings Using a stratified two-stage cluster sample design, four cross-sectional studies were undertaken between March-June 2007 across three livelihood groups in an area of low intensity malaria transmission in South Central Somalia. Information on bed net use; age; and sex of all participants were recorded. A finger prick blood sample was taken from participants to examine for parasitaemia. Mantel-Haenzel methods were used to measure the effect of net use on parasitaemia adjusting for livelihood; age; and sex. A total of 10,587 individuals of all ages were seen of which 10,359 provided full information. Overall net use and parasite prevalence were 12.4% and 15.7% respectively. Age-specific protective effectiveness (PE) of bed net ranged from 39% among <5 years to 72% among 5–14 years old. Overall PE of bed nets was 54% (95% confidence interval 44%–63%) after adjusting for livelihood; sex; and age. Conclusions and Significance Bed nets confer high protection against parasite infection in South Central Somalia. In such areas where baseline transmission is low, however, the absolute reductions in parasitaemia due to wide-scale net use will be relatively small raising questions on the cost-effectiveness of covering millions of people living in such settings in Africa with nets. Further understanding of the progress of disease upon infection against the cost of averting its consequent burden in low transmission areas of Africa is therefore required. PMID:18461178

  16. 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

  17. Parasite-specific lactate dehydrogenase for the diagnosis of Plasmodium falciparum infection in an endemic area in west Uganda.

    PubMed

    Jelinek, T; Kilian, A H; Henk, M; Mughusu, E B; Nothdurft, H D; Löscher, T; Knobloch, J; Van Sonnenburg, F

    1996-04-01

    The measurement of parasite lactate dehydrogenase (pLDH) has been presented as an easy and rapid method for the diagnosis of malaria in humans. In order to evaluate the sensitivity and specificity of such a test we examined blood samples from 429 Ugandan patients. While pLDH activity was significantly linked to parasitaemia, sensitivity and specificity were found to be rather low at 58.8 and 62.2% respectively. The positive and negative predictive values failed to meet necessary standards. We conclude that the methods of measurement of pLDH activity in malaria infection, although potentially useful for the fast diagnosis of malaria, need to be improved to be of true value in endemic areas.

  18. The use of mosquito nets and the prevalence of Plasmodium falciparum infection in rural South Central Somalia.

    PubMed

    Noor, Abdisalan M; Moloney, Grainne; Borle, Mohamed; Fegan, Greg W; Shewchuk, Tanya; Snow, Robert W

    2008-05-07

    There have been resurgent efforts in Africa to estimate the public health impact of malaria control interventions such as insecticide treated nets (ITNs) following substantial investments in scaling-up coverage in the last five years. Little is known, however, on the effectiveness of ITN in areas of Africa that support low transmission. This hinders the accurate estimation of impact of ITN use on disease burden and its cost-effectiveness in low transmission settings. Using a stratified two-stage cluster sample design, four cross-sectional studies were undertaken between March-June 2007 across three livelihood groups in an area of low intensity malaria transmission in South Central Somalia. Information on bed net use; age; and sex of all participants were recorded. A finger prick blood sample was taken from participants to examine for parasitaemia. Mantel-Haenzel methods were used to measure the effect of net use on parasitaemia adjusting for livelihood; age; and sex. A total of 10,587 individuals of all ages were seen of which 10,359 provided full information. Overall net use and parasite prevalence were 12.4% and 15.7% respectively. Age-specific protective effectiveness (PE) of bed net ranged from 39% among <5 years to 72% among 5-14 years old. Overall PE of bed nets was 54% (95% confidence interval 44%-63%) after adjusting for livelihood; sex; and age. Bed nets confer high protection against parasite infection in South Central Somalia. In such areas where baseline transmission is low, however, the absolute reductions in parasitaemia due to wide-scale net use will be relatively small raising questions on the cost-effectiveness of covering millions of people living in such settings in Africa with nets. Further understanding of the progress of disease upon infection against the cost of averting its consequent burden in low transmission areas of Africa is therefore required.

  19. Modelling the cost-effectiveness of mass screening and treatment for reducing Plasmodium falciparum malaria burden

    PubMed Central

    2013-01-01

    Background Past experience and modelling suggest that, in most cases, mass treatment strategies are not likely to succeed in interrupting Plasmodium falciparum malaria transmission. However, this does not preclude their use to reduce disease burden. Mass screening and treatment (MSAT) is preferred to mass drug administration (MDA), as the latter involves massive over-use of drugs. This paper reports simulations of the incremental cost-effectiveness of well-conducted MSAT campaigns as a strategy for P. falciparum malaria disease-burden reduction in settings with varying receptivity (ability of the combined vector population in a setting to transmit disease) and access to case management. Methods MSAT incremental cost-effectiveness ratios (ICERs) were estimated in different sub-Saharan African settings using simulation models of the dynamics of malaria and a literature-based MSAT cost estimate. Imported infections were simulated at a rate of two per 1,000 population per annum. These estimates were compared to the ICERs of scaling up case management or insecticide-treated net (ITN) coverage in each baseline health system, in the absence of MSAT. Results MSAT averted most episodes, and resulted in the lowest ICERs, in settings with a moderate level of disease burden. At a low pre-intervention entomological inoculation rate (EIR) of two infectious bites per adult per annum (IBPAPA) MSAT was never more cost-effective than scaling up ITNs or case management coverage. However, at pre-intervention entomological inoculation rates (EIRs) of 20 and 50 IBPAPA and ITN coverage levels of 40 or 60%, respectively, the ICER of MSAT was similar to that of scaling up ITN coverage further. Conclusions In all the transmission settings considered, achieving a minimal level of ITN coverage is a “best buy”. At low transmission, MSAT probably is not worth considering. Instead, MSAT may be suitable at medium to high levels of transmission and at moderate ITN coverage. If undertaken as a

  20. 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

  1. 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.

  2. Reduced Impact of Pyrimethamine Drug Pressure on Plasmodium malariae Dihydrofolate Reductase Gene

    PubMed Central

    Khim, Nimol; Kim, Saorin; Bouchier, Christiane; Tichit, Magali; Ariey, Frédéric; Fandeur, Thierry; Chim, Pheaktra; Ke, Sopheakvatey; Sum, Sarorn; Man, Somnang; Ratsimbasoa, Arsène; Durand, Rémy

    2012-01-01

    Molecular investigations performed following the emergence of sulfadoxine-pyrimethamine (SP) resistance in Plasmodium falciparum have allowed the identification of the dihydrofolate reductase (DHFR) enzyme as the target of pyrimethamine. Although clinical cases of Plasmodium malariae are not usually treated with antifolate therapy, incorrect diagnosis and the high frequency of undetected mixed infections has probably exposed non-P. falciparum parasites to antifolate therapy in many areas. In this context, we aimed to assess the worldwide genetic diversity of the P. malariae dhfr gene in 123 samples collected in Africa and Asia, areas with different histories of SP use. Among the 10 polymorphic sites found, we have observed 7 new mutations (K55E, S58R, S59A, F168S, N194S, D207G, and T221A), which led us to describe 6 new DHFR proteins. All isolates from African countries were classified as wild type, while new mutations and haplotypes were recognized as exclusive to Madagascar (except for the double mutations at nucleotides 341 and 342 [S114N] found in one Cambodian isolate). Among these nonsynonymous mutations, two were likely related to pyrimethamine resistance: S58R (corresponding to C59R in P. falciparum and S58R in Plasmodium vivax; observed in one Malagasy sample) and S114N (corresponding to S108N in P. falciparum and S117N in P. vivax; observed in three Cambodian samples). PMID:22123682

  3. Reduced impact of pyrimethamine drug pressure on Plasmodium malariae dihydrofolate reductase gene.

    PubMed

    Khim, Nimol; Kim, Saorin; Bouchier, Christiane; Tichit, Magali; Ariey, Frédéric; Fandeur, Thierry; Chim, Pheaktra; Ke, Sopheakvatey; Sum, Sarorn; Man, Somnang; Ratsimbasoa, Arsène; Durand, Rémy; Ménard, Didier

    2012-02-01

    Molecular investigations performed following the emergence of sulfadoxine-pyrimethamine (SP) resistance in Plasmodium falciparum have allowed the identification of the dihydrofolate reductase (DHFR) enzyme as the target of pyrimethamine. Although clinical cases of Plasmodium malariae are not usually treated with antifolate therapy, incorrect diagnosis and the high frequency of undetected mixed infections has probably exposed non-P. falciparum parasites to antifolate therapy in many areas. In this context, we aimed to assess the worldwide genetic diversity of the P. malariae dhfr gene in 123 samples collected in Africa and Asia, areas with different histories of SP use. Among the 10 polymorphic sites found, we have observed 7 new mutations (K55E, S58R, S59A, F168S, N194S, D207G, and T221A), which led us to describe 6 new DHFR proteins. All isolates from African countries were classified as wild type, while new mutations and haplotypes were recognized as exclusive to Madagascar (except for the double mutations at nucleotides 341 and 342 [S114N] found in one Cambodian isolate). Among these nonsynonymous mutations, two were likely related to pyrimethamine resistance: S58R (corresponding to C59R in P. falciparum and S58R in Plasmodium vivax; observed in one Malagasy sample) and S114N (corresponding to S108N in P. falciparum and S117N in P. vivax; observed in three Cambodian samples).

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

    PubMed Central

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

    2014-01-01

    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. PMID:24850912

  5. Ivermectin inhibits the sporogony of Plasmodium falciparum in Anopheles gambiae

    PubMed Central

    2012-01-01

    Background When ingested in a blood meal, ivermectin has been shown to reduce the survivorship of Anopheles gambiae in the laboratory and field. Furthermore, ivermectin mass drug administrations in Senegal have been shown to reduce the proportion of Plasmodium falciparum-sporozoite-containing An. gambiae. This study addresses whether ivermectin inhibits sporogony of P. falciparum in An. gambiae. Methods Anophele gambiae s.s. G3 strain were fed two concentrations of ivermectin (LC25 and LC5) along with P. falciparum NF54 in human blood meals at staggered intervals. Mosquitoes ingested ivermectin concurrent with parasites (DPI 0), or at three (DPI 3), six (DPI 6), and nine (DPI 9) days post parasite ingestion, or three days prior (DPI −3) to parasite ingestion. Mosquitoes were dissected at seven, twelve or fourteen days post parasite ingestion and either oocyst or sporozoite prevalence was recorded. To determine if P. falciparum sporozoite-containing An. gambiae were more susceptible to ivermectin than uninfected controls, survivorship was recorded for mosquitoes which ingested P. falciparum or control blood meal on DPI 0 and then a second blood meal containing ivermectin (LC25) on DPI 14. Results Ivermectin (LC25) co-ingested (DPI 0) with parasites reduced the proportion of An. gambiae that developed oocysts (χ2 = 15.4842, P = 0.0002) and sporozoites (χ2 = 19.9643, P < 0.0001). Ivermectin (LC25) ingested DPI 6 (χ2 = 8.5103, P = 0.0044) and 9 (χ2 = 14.7998, P < 0.0001) reduced the proportion of An. gambiae that developed sporozoites but not when ingested DPI 3 (χ2 = 0.0113, P = 1). Ivermectin (LC5) co-ingested (DPI 0) with parasites did not reduce the proportion of An. gambiae that developed oocysts (χ2 = 4.2518, P = 0.0577) or sporozoites (χ2 = 2.3636, P = 0.1540), however, when ingested DPI −3 the proportion of An. gambiae that developed sporozoites was reduced (χ2 = 8.4806, P = 0.0047). Plasmodium falciparum infection significantly reduced the

  6. Characterization of a Plasmodium falciparum macrophage-migration inhibitory factor homologue.

    PubMed

    Cordery, Damien V; Kishore, Uday; Kyes, Sue; Shafi, Mohammed J; Watkins, Katherine R; Williams, Thomas N; Marsh, Kevin; Urban, Britta C

    2007-03-15

    Macrophage-migration inhibitory factor (MIF), one of the first cytokines described, has a broad range of proinflammatory properties. The genome sequencing project of Plasmodium falciparum identified a parasite homologue of MIF. The protein is expressed during the asexual blood stages of the parasite life cycle that cause malarial disease. The identification of a parasite homologue of MIF raised the question of whether it affects monocyte function in a manner similar to its human counterpart. Recombinant P. falciparum MIF (PfMIF) was generated and used in vitro to assess its influence on monocyte function. Antibodies generated against PfMIF were used to determine the expression profile and localization of the protein in blood-stage parasites. Antibody responses to PfMIF were determined in Kenyan children with acute malaria and in control subjects. PfMIF protein was expressed in asexual blood-stage parasites, localized to the Maurer's cleft. In vitro treatment of monocytes with PfMIF inhibited random migration and reduced the surface expression of Toll-like receptor (TLR) 2, TLR4, and CD86. These results indicate that PfMIF is released during blood-stage malaria and potentially modulates the function of monocytes during acute P. falciparum infection.

  7. 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.

  8. 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.

  9. 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; 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

    2015-10-08

    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.

  10. 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. © 2016 The Author(s).

  11. 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

  12. Cytokine Profiling in Immigrants with Clinical Malaria after Extended Periods of Interrupted Exposure to Plasmodium falciparum

    PubMed Central

    Moncunill, Gemma; Mayor, Alfredo; Bardají, Azucena; Puyol, Laura; Nhabomba, Augusto; Barrios, Diana; Aguilar, Ruth; Pinazo, María-Jesús; Almirall, Mercè; Soler, Cristina; Muñoz, José; Gascón, Joaquim; Dobaño, Carlota

    2013-01-01

    Immunity to malaria is believed to wane with time in the absence of exposure to Plasmodium falciparum infection, but immunoepidemiological data on longevity of immunity remain controversial. We quantified serum cytokines and chemokines by suspension array technology as potential biomarkers for durability of immunity in immigrants with clinical malaria after years without parasite exposure. These were compared to serum/plasma profiles in naïve adults (travelers) and semi-immune adults under continuous exposure, with malaria, along with immigrant and traveler patients without malaria. Immigrants had higher levels of IL-2, IL-5 and IL-8 compared to semi-immune adults with malaria (P≤0.0200). Time since immigration correlated with increased IL-2 (rho=0.2738P=0.0495) and IFN-γ (rho=0.3044P=0.0282). However, immigrants did not show as high IFN-γ concentrations as travelers during a first malaria episode (P<0.0001). Immigrants and travelers with malaria had higher levels of IFN-γ, IL-6, and IL-10 (P<0.0100) than patients with other diseases, and IL-8 and IL-1β were elevated in immigrants with malaria (P<0.0500). Therefore, malaria patients had a characteristic strong pro-inflammatory/Th1 signature. Upon loss of exposure, control of pro-inflammatory responses and tolerance to P. falciparum appeared to be reduced. Understanding the mechanisms to maintain non-pathogenic effector responses is important to develop new malaria control strategies. PMID:23967342

  13. 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

    2016-08-10

    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.

  14. Host erythrocyte polymorphisms and exposure to Plasmodium falciparum in Papua New Guinea

    PubMed Central

    Fowkes, Freya JI; Michon, Pascal; Pilling, Lynn; Ripley, Ruth M; Tavul, Livingstone; Imrie, Heather J; Woods, Caira M; Mgone, Charles S; Luty, Adrian JF; Day, Karen P

    2008-01-01

    Background The protection afforded by human erythrocyte polymorphisms against the malaria parasite, Plasmodium falciparum, has been proposed to be due to reduced ability of the parasite to invade or develop in erythrocytes. If this were the case, variable levels of parasitaemia and rates of seroconversion to infected-erythrocyte variant surface antigens (VSA) should be seen in different host genotypes. Methods To test this hypothesis, P. falciparum parasitaemia and anti-VSA antibody levels were measured in a cohort of 555 asymptomatic children from an area of intense malaria transmission in Papua New Guinea. Linear mixed models were used to investigate the effect of α+-thalassaemia, complement receptor-1 and south-east Asian ovalocytosis, as well as glucose-6-phosphate dehydrogenase deficiency and ABO blood group on parasitaemia and age-specific seroconversion to VSA. Results No host polymorphism showed a significant association with both parasite prevalence/density and age-specific seroconversion to VSA. Conclusion Host erythrocyte polymorphisms commonly found in Papua New Guinea do not effect exposure to blood stage P. falciparum infection. This contrasts with data for sickle cell trait and highlights that the above-mentioned polymorphisms may confer protection against malaria via distinct mechanisms. PMID:18173836

  15. Immunity to malaria and naturally acquired antibodies to the circumsporozoite protein of Plasmodium falciparum.

    PubMed

    Hoffman, S L; Wistar, R; Ballou, W R; Hollingdale, M R; Wirtz, R A; Schneider, I; Marwoto, H A; Hockmeyer, W T

    1986-09-04

    A candidate Plasmodium falciparum sporozoite vaccine, R32tet32, which includes 32 tetrapeptide repeats derived from the circumsporozoite protein of P. falciparum, has been developed on the basis of the hypothesis that antibodies to the repeat region of this protein will protect against sporozoite infection. The results of two in vitro assays, the circumsporozoite precipitation reaction and the inhibition of sporozoite invasion into hepatoma cells, are thought to indicate protective immunity. We therefore tested serum samples from persons living in a hyperendemic malarious area of Indonesia for antibodies against R32tet32 and for their ability to produce circumsporozoite precipitation and to inhibit sporozoite invasion of hepatoma cells. The prevalence and mean titer of antibody against R32tet32 increased with the age of the subjects, whereas the prevalence of P. falciparum infection in the community decreased. Only serum samples with IgG or IgM R32tet32 antibody titers greater than or equal to 1/800 had precipitation activity and invasion-inhibiting activity of more than 75 percent. When the serum samples were fractionated by affinity chromatography, only the fractions containing purified human antibody to R32tet32 were found to contain this activity. These data support the hypotheses that antibodies to the circumsporozoite protein are important in reducing the prevalence of malaria with increasing age among persons in areas in which malaria is endemic and that vaccine-elicited antibody to the circumsporozoite repeat region will protect against infection with P. falciparum sporozoites.

  16. Desferrioxamine suppresses Plasmodium falciparum in Aotus monkeys.

    PubMed

    Pollack, S; Rossan, R N; Davidson, D E; Escajadillo, A

    1987-02-01

    Clinical observation has suggested that iron deficiency may be protective in malaria, and we have found that desferrioxamine (DF), an iron-specific chelating agent, inhibited Plasmodium falciparum growth in vitro. It was difficult to be confident that DF would be effective in an intact animal, however, because continuous exposure to DF was required in vitro and, in vivo, DF is rapidly excreted. Also, the in vitro effect of DF was overcome by addition of iron to the culture and in vivo there are potentially high local iron concentrations when iron is absorbed from the diet or released from reticuloendothelial cells. We now show that DF given by constant subcutaneous infusion does suppress parasitemia in P. falciparum-infected Aotus monkeys.

  17. Hemoglobinopathies: slicing the Gordian knot of Plasmodium falciparum malaria pathogenesis.

    PubMed

    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

  18. 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

  19. Whole-body imaging of sequestration of Plasmodium falciparum in the rat.

    PubMed

    Pettersson, Fredrik; Vogt, Anna M; Jonsson, Cathrine; Mok, Bobo W; Shamaei-Tousi, Alireza; Bergström, Sven; Chen, Qijun; Wahlgren, Mats

    2005-11-01

    The occlusion of vessels by packed Plasmodium falciparum-infected (iRBC) and uninfected erythrocytes is a characteristic postmortem finding in the microvasculature of patients with severe malaria. Here we have employed immunocompetent Sprague-Dawley rats to establish sequestration in vivo. Human iRBC cultivated in vitro and purified in a single step over a magnet were labeled with 99mtechnetium, injected into the tail vein of the rat, and monitored dynamically for adhesion in the microvasculature using whole-body imaging or imaging of the lungs subsequent to surgical removal. iRBC of different lines and clones sequester avidly in vivo while uninfected erythrocytes did not. Histological examination revealed that a multiadhesive parasite adhered in the larger microvasculature, inducing extensive intravascular changes while CD36- and chondroitin sulfate A-specific parasites predominantly sequester in capillaries, inducing no or minor pathology. Removal of the adhesive ligand Plasmodium falciparum erythrocyte membrane protein 1 (PfEMP1), preincubation of the iRBC with sera to PfEMP1 or preincubation with soluble PfEMP1-receptors prior to injection significantly reduced the sequestration. The specificity of iRBC binding to the heterologous murine receptors was confirmed in vitro, using primary rat lung endothelial cells and rat lung cryosections. In offering flow dynamics, nonmanipulated endothelial cells, and an intact immune system, we believe this syngeneic animal model to be an important complement to existing in vitro systems for the screening of vaccines and adjunct therapies aiming at the prevention and treatment of severe malaria.

  20. Deformability based sorting of red blood cells improves diagnostic sensitivity for malaria caused by Plasmodium falciparum.

    PubMed

    Guo, Quan; Duffy, Simon P; Matthews, Kerryn; Deng, Xiaoyan; Santoso, Aline T; Islamzada, Emel; Ma, Hongshen

    2016-02-21

    The loss of red blood cell (RBC) deformability is part of the pathology of many diseases. In malaria caused by Plasmodium falciparum infection, metabolism of hemoglobin by the parasite results in progressive reduction in RBC deformability that is directly correlated with the growth and development of the parasite. The ability to sort RBCs based on deformability therefore provides a means to isolate pathological cells and to study biochemical events associated with disease progression. Existing methods have not been able to sort RBCs based on deformability or to effectively enrich for P. falciparum infected RBCs at clinically relevant concentrations. Here, we develop a method to sort RBCs based on deformability and demonstrate the ability to enrich the concentration of ring-stage P. falciparum infected RBCs (Pf-iRBCs) by >100× from clinically relevant parasitemia (<0.01%). Deformability based sorting of RBCs is accomplished using ratchet transport through asymmetrical constrictions using oscillatory flow. This mechanism provides dramatically improved selectivity over previous biophysical methods by preventing the accumulation of cells in the filter microstructure to ensure that consistent filtration forces are applied to each cell. We show that our approach dramatically improves the sensitivity of malaria diagnosis performed using both microscopy and rapid diagnostic test by converting samples with difficult-to-detect parasitemia (<0.01%) into samples with easily detectable parasitemia (>0.1%).

  1. Dihydroartemisinin-piperaquine resistance in Plasmodium falciparum malaria in Cambodia: a multisite prospective cohort study.

    PubMed

    Amaratunga, Chanaki; Lim, Pharath; Suon, Seila; Sreng, Sokunthea; Mao, Sivanna; Sopha, Chantha; Sam, Baramey; Dek, Dalin; Try, Vorleak; Amato, Roberto; Blessborn, Daniel; Song, Lijiang; Tullo, Gregory S; Fay, Michael P; Anderson, Jennifer M; Tarning, Joel; Fairhurst, Rick M

    2016-03-01

    Artemisinin resistance in Plasmodium falciparum threatens to reduce the efficacy of artemisinin combination therapies (ACTs), thus compromising global efforts to eliminate malaria. Recent treatment failures with dihydroartemisinin-piperaquine, the current first-line ACT in Cambodia, suggest that piperaquine resistance may be emerging in this country. We explored the relation between artemisinin resistance and dihydroartemisinin-piperaquine failures, and sought to confirm the presence of piperaquine-resistant P falciparum infections in Cambodia. In this prospective cohort study, we enrolled patients aged 2-65 years with uncomplicated P falciparum malaria in three Cambodian provinces: Pursat, Preah Vihear, and Ratanakiri. Participants were given standard 3-day courses of dihydroartemisinin-piperaquine. Peripheral blood parasite densities were measured until parasites cleared and then weekly to 63 days. The primary outcome was recrudescent P falciparum parasitaemia within 63 days. We measured piperaquine plasma concentrations at baseline, 7 days, and day of recrudescence. We assessed phenotypic and genotypic markers of drug resistance in parasite isolates. The study is registered with ClinicalTrials.gov, number NCT01736319. Between Sept 4, 2012, and Dec 31, 2013, we enrolled 241 participants. In Pursat, where artemisinin resistance is entrenched, 37 (46%) of 81 patients had parasite recrudescence. In Preah Vihear, where artemisinin resistance is emerging, ten (16%) of 63 patients had recrudescence and in Ratanakiri, where artemisinin resistance is rare, one (2%) of 60 patients did. Patients with recrudescent P falciparum infections were more likely to have detectable piperaquine plasma concentrations at baseline compared with non-recrudescent patients, but did not differ significantly in age, initial parasite density, or piperaquine plasma concentrations at 7 days. Recrudescent parasites had a higher prevalence of kelch13 mutations, higher piperaquine 50% inhibitory

  2. Dihydroartemisinin–piperaquine resistance in Plasmodium falciparum malaria in Cambodia: a multisite prospective cohort study

    PubMed Central

    Amaratunga, Chanaki; Lim, Pharath; Suon, Seila; Sreng, Sokunthea; Mao, Sivanna; Sopha, Chantha; Sam, Baramey; Dek, Dalin; Try, Vorleak; Amato, Roberto; Blessborn, Daniel; Song, Lijiang; Tullo, Gregory S; Fay, Michael P; Anderson, Jennifer M; Tarning, Joel; Fairhurst, Rick M

    2016-01-01

    Background Artemisinin resistance in Plasmodium falciparum threatens to reduce the efficacy of artemisinin combination therapies (ACTs), thus compromising global efforts to eliminate malaria. Recent treatment failures with dihydroartemisinin-piperaquine, the current first-line ACT in Cambodia, suggest that piperaquine resistance may be emerging in this country. We explored the relation between artemisinin resistance and dihydroartemisinin–piperaquine failures, and sought to confirm the presence of piperaquine-resistant P falciparum infections in Cambodia. Methods In this prospective cohort study, we enrolled patients aged 2–65 years with uncomplicated P falciparum malaria in three Cambodian provinces: Pursat, Preah Vihear, and Ratanakiri. Participants were given standard 3-day courses of dihydroartemisinin–piperaquine. Peripheral blood parasite densities were measured until parasites cleared and then weekly to 63 days. The primary outcome was recrudescent P falciparum parasitaemia within 63 days. We measured piperaquine plasma concentrations at baseline, 7 days, and day of recrudescence. We assessed phenotypic and genotypic markers of drug resistance in parasite isolates. The study is registered with ClinicalTrials.gov, number NCT01736319. Findings Between Sept 4, 2012, and Dec 31, 2013, we enrolled 241 participants. In Pursat, where artemisinin resistance is entrenched, 37 (46%) of 81 patients had parasite recrudescence. In Preah Vihear, where artemisinin resistance is emerging, ten (16%) of 63 patients had recrudescence and in Ratanakiri, where artemisinin resistance is rare, one (2%) of 60 patients did. Patients with recrudescent P falciparum infections were more likely to have detectable piperaquine plasma concentrations at baseline compared with non-recrudescent patients, but did not differ significantly in age, initial parasite density, or piperaquine plasma concentrations at 7 days. Recrudescent parasites had a higher prevalence of kelch13 mutations

  3. Drug resistance associated genetic polymorphisms in Plasmodium falciparum and Plasmodium vivax collected in Honduras, Central America.

    PubMed

    Jovel, Irina T; Mejía, Rosa E; Banegas, Engels; Piedade, Rita; Alger, Jackeline; Fontecha, Gustavo; Ferreira, Pedro E; Veiga, Maria I; Enamorado, Irma G; Bjorkman, Anders; Ursing, Johan

    2011-12-19

    In Honduras, chloroquine and primaquine are recommended and still appear to be effective for treatment of Plasmodium falciparum and Plasmodium vivax malaria. The aim of this study was to determine the proportion of resistance associated genetic polymorphisms in P. falciparum and P. vivax collected in Honduras. Blood samples were collected from patients seeking medical attention at the Hospital Escuela in Tegucigalpa from 2004 to 2006 as well as three regional hospitals, two health centres and one regional laboratory during 2009. Single nucleotide polymorphisms in P. falciparum chloroquine resistance transporter (pfcrt), multidrug resistance 1 (pfmdr1), dihydrofolate reductase (pfdhfr) and dihydropteroate synthase (pfdhps) genes and in P. vivax multidrug resistance 1 (pvmdr1) and dihydrofolate reductase (pvdhfr) genes were detected using PCR based methods. Thirty seven P. falciparum and 64 P. vivax samples were collected. All P. falciparum infections acquired in Honduras carried pfcrt, pfmdr1, pfdhps and pfdhfr alleles associated with chloroquine, amodiaquine and sulphadoxine-pyrimethamine sensitivity only. One patient with parasites acquired on a Pacific Island had pfcrt 76 T and pfmdr1 86Y alleles. That patient and a patient infected in West Africa had pfdhfr 51I, 59 R and 108 N alleles. Pvmdr1 976 F was found in 7/37 and two copies of pvmdr1 were found in 1/37 samples. Pvdhfr 57 L + 58 R was observed in 2/57 samples. The results indicate that P. falciparum from Honduras remain sensitive to chloroquine and sulphadoxine-pyrimethamine. This suggests that chloroquine and sulphadoxine-pyrimethamine should be efficacious for treatment of uncomplicated P. falciparum malaria, supporting current national treatment guidelines. However, genetic polymorphisms associated with chloroquine and sulphadoxine-pyrimethamine tolerance were detected in local P. vivax and imported P. falciparum infections. Continuous monitoring of the prevalence of drug resistant/tolerant P

  4. Drug resistance associated genetic polymorphisms in Plasmodium falciparum and Plasmodium vivax collected in Honduras, Central America

    PubMed Central

    2011-01-01

    Background In Honduras, chloroquine and primaquine are recommended and still appear to be effective for treatment of Plasmodium falciparum and Plasmodium vivax malaria. The aim of this study was to determine the proportion of resistance associated genetic polymorphisms in P. falciparum and P. vivax collected in Honduras. Methods Blood samples were collected from patients seeking medical attention at the Hospital Escuela in Tegucigalpa from 2004 to 2006 as well as three regional hospitals, two health centres and one regional laboratory during 2009. Single nucleotide polymorphisms in P. falciparum chloroquine resistance transporter (pfcrt), multidrug resistance 1 (pfmdr1), dihydrofolate reductase (pfdhfr) and dihydropteroate synthase (pfdhps) genes and in P. vivax multidrug resistance 1 (pvmdr1) and dihydrofolate reductase (pvdhfr) genes were detected using PCR based methods. Results Thirty seven P. falciparum and 64 P. vivax samples were collected. All P. falciparum infections acquired in Honduras carried pfcrt, pfmdr1, pfdhps and pfdhfr alleles associated with chloroquine, amodiaquine and sulphadoxine-pyrimethamine sensitivity only. One patient with parasites acquired on a Pacific Island had pfcrt 76 T and pfmdr1 86Y alleles. That patient and a patient infected in West Africa had pfdhfr 51I, 59 R and 108 N alleles. Pvmdr1 976 F was found in 7/37 and two copies of pvmdr1 were found in 1/37 samples. Pvdhfr 57 L + 58 R was observed in 2/57 samples. Conclusion The results indicate that P. falciparum from Honduras remain sensitive to chloroquine and sulphadoxine-pyrimethamine. This suggests that chloroquine and sulphadoxine-pyrimethamine should be efficacious for treatment of uncomplicated P. falciparum malaria, supporting current national treatment guidelines. However, genetic polymorphisms associated with chloroquine and sulphadoxine-pyrimethamine tolerance were detected in local P. vivax and imported P. falciparum infections. Continuous monitoring of the prevalence

  5. Typing of Plasmodium falciparum DNA from 2 years old Giemsa-stained dried blood spots using nested polymerase chain reaction assay.

    PubMed

    Kumar, D; Dhiman, S; Rabha, B; Goswami, D; Yadav, K; Deka, M; Veer, V; Baruah, I

    2016-01-01

    A panel of 129 Giemsa-stained thick blood spots (TBS) confirmed for Plasmodium falciparum infection having different levels of parasite density were collected from a malaria endemic area. DNA was extracted and nested polymerase chain reaction (PCR) assay was performed to amplify P. falciparum DNA. Nested PCR assay successfully amplified P. falciparum DNA at a very low parasitaemia of ~10 parasites/μl of blood. Current PCR assay is very simple and can be used retrospectively to monitor the invasion and prevalence of different Plasmodium species in endemic areas.

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

    PubMed

    Obare, Peter; Ogutu, Bernhards; Adams, Mohammed; Odera, James Sande; Lilley, Ken; Dosoo, David; Adhiambo, Christine; Owusu-Agyei, Seth; Binka, Fred; Wanja, Elizabeth; Johnson, Jacob

    2013-03-27

    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. 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. 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 < 0.05). These findings suggest that the misclassification of malaria

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

    PubMed Central

    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

  8. Effect of Plasmodium falciparum malaria parasites on haematological parameters in Ghanaian children.

    PubMed

    Squire, D S; Asmah, R H; Brown, C A; Adjei, D N; Obeng-Nkrumah, N; Ayeh-Kumi, P F

    2016-06-01

    Malaria is hyper-endemic in Ghana. Haematological alterations in the disease pathology may offer complimentary criteria to improve clinical and microscopy diagnosis. Our primary outcome was to evaluate haematological parameters in children with Plasmodium falciparum infections and report their predictive risk and diagnostic performance for malaria infections in Ghana. Haematological data, including thin and thick blood films were examined for children less than 12 years of age in a multicenter-based active case finding approach. Haematological changes were common in P. falciparum infected children and more pronounced in severe malaria cases. More so, a unit increase in parasiteamia increased the odds for severe malaria infection by 93 % [OR, 95 % CI: 1.93 (1.28-2.91); P value = 0.02]. In multivariate regression, low haemoglobin was a significant haematological change in predicting P. falciparum infections [OR, 95 % CI: 3.20 (1.26-7.09); P value = 0.001]. Low haemoglobin levels <11 g/dl was the most reliable indicator for P. falciparum infections [with a sensitivity of (64 %), specificity (71 %), positive predictive value (83 %) and likelihood ratio (2.2)]-even when evaluated in combination with leucocytosis, lymphocytopaenia and high neutrophil counts >7,500 µL. In malaria endemic settings, low haemoglobin concentration (<11 g/dl) in children with febrile illness should prompt a more diligent search for the malarial parasite to limit the misuse and abuse of anti-malarial drugs.

  9. An unusual case of Plasmodium vivax malaria monoinfection associated with crescentic glomerulonephritis: a need for vigilance.

    PubMed

    Patel, Mohan P; Kute, Vivek B; Gumber, Manoj R; Gera, Dinesh N; Shah, Pankaj R; Patel, Himanshu V; Trivedi, Hargovind L; Vanikar, Aruna V

    2013-01-01

    Plasmodium vivax infection is increasingly a major public health burden and the second most frequent human malaria. Higher levels of clinical severity and chloroquine resistance are major factors responsible for such increases. Malarial glomerular injury is uncommon and mainly observed in Plasmodium malariae-infected patients. Occasionally, transient immune complex-mediated glomerulonephritis is associated with Plasmodium falciparum infection. Coexistent crescentic glomerulonephritis and vivax malaria have not previously been reported. We report a fatal case of P. vivax malaria, who presented with acute renal failure. P. vivax monoinfection status was diagnosed with peripheral blood smear and rapid antigen test. Further evaluation for renal failure related to systemic illness and immunological markers were inconclusive. He was treated with antimalarial drugs, hemodialysis, and supportive therapy. Renal biopsy performed for nonrecovering renal failure reveled crescentic glomerulonephritis. This case highlights the need to thoroughly search for malaria-associated crescentic glomerulonephritis using renal biopsy after nonrecovering renal failure.

  10. Strategies for Understanding and Reducing the Plasmodium vivax and Plasmodium ovale Hypnozoite Reservoir in Papua New Guinean Children: A Randomised Placebo-Controlled Trial and Mathematical Model

    PubMed Central

    Robinson, Leanne J.; Wampfler, Rahel; Betuela, Inoni; Karl, Stephan; White, Michael T.; Li Wai Suen, Connie S. N.; Hofmann, Natalie E.; Kinboro, Benson; Waltmann, Andreea; Brewster, Jessica; Lorry, Lina; Tarongka, Nandao; Samol, Lornah; Silkey, Mariabeth; Bassat, Quique; Siba, Peter M.; Schofield, Louis; Felger, Ingrid; Mueller, Ivo

    2015-01-01

    Background The undetectable hypnozoite reservoir for relapsing Plasmodium vivax and P. ovale malarias presents a major challenge for malaria control and elimination in endemic countries. This study aims to directly determine the contribution of relapses to the burden of P. vivax and P. ovale infection, illness, and transmission in Papua New Guinean children. Methods and Findings From 17 August 2009 to 20 May 2010, 524 children aged 5–10 y from East Sepik Province in Papua New Guinea (PNG) participated in a randomised double-blind placebo-controlled trial of blood- plus liver-stage drugs (chloroquine [CQ], 3 d; artemether-lumefantrine [AL], 3 d; and primaquine [PQ], 20 d, 10 mg/kg total dose) (261 children) or blood-stage drugs only (CQ, 3 d; AL, 3 d; and placebo [PL], 20 d) (263 children). Participants, study staff, and investigators were blinded to the treatment allocation. Twenty children were excluded during the treatment phase (PQ arm: 14, PL arm: 6), and 504 were followed actively for 9 mo. During the follow-up time, 18 children (PQ arm: 7, PL arm: 11) were lost to follow-up. Main primary and secondary outcome measures were time to first P. vivax infection (by qPCR), time to first clinical episode, force of infection, gametocyte positivity, and time to first P. ovale infection (by PCR). A basic stochastic transmission model was developed to estimate the potential effect of mass drug administration (MDA) for the prevention of recurrent P. vivax infections. Targeting hypnozoites through PQ treatment reduced the risk of having at least one qPCR-detectable P. vivax or P. ovale infection during 8 mo of follow-up (P. vivax: PQ arm 0.63/y versus PL arm 2.62/y, HR = 0.18 [95% CI 0.14, 0.25], p < 0.001; P. ovale: 0.06 versus 0.14, HR = 0.31 [95% CI 0.13, 0.77], p = 0.011) and the risk of having at least one clinical P. vivax episode (HR = 0.25 [95% CI 0.11, 0.61], p = 0.002). PQ also reduced the molecular force of P. vivax blood-stage infection in the first 3 mo of

  11. Plasmodium coatneyi in the rhesus monkey (Macaca mulatta) as a model of malaria in pregnancy.

    PubMed

    Davison, B B; Cogswell, F B; Baskin, G B; Falkenstein, K P; Henson, E W; Tarantal, A F; Krogstad, D J

    1998-08-01

    Pregnant women with Plasmodium falciparum infection are at increased risk for complications such as anemia and cerebral malaria. In addition, the infants of these women suffer intrauterine growth retardation (IUGR), low birth weight (LBW), congenital infection, and high infant mortality. Although much has been learned from studies of malaria during human pregnancy, progress has been limited by the lack of a suitable animal model. Nonhuman primates are of particular interest because, other than the armadillo, they are the only animals with a discoidal, villous, hemochorial placenta like that of humans. We have established a model of malaria during human pregnancy by inoculating pregnant rhesus monkeys (Macaca mulatta) with Plasmodium coatneyi (a sequestering parasite) during the first trimester. In our initial experiment, four monkeys were inoculated with a fresh inoculum containing 10(8) viable parasites from an infected donor monkey. All four monkeys became parasitemic seven days postinoculation (PI) and three monkeys aborted 7-10 days PI coincident with high peak parasitemias (41,088-374,325 parasites/mm3). Although abortion is one of the outcomes observed in Plasmodium-infected women, the intent of this study was to examine the effects of Plasmodium infection throughout gestation. Since the rapid onset of high parasitemia may have been responsible for the abortions, a decision was made to reduce the size of the effective inoculum. Six additional pregnant monkeys were inoculated with a frozen isolate taken from the same donor containing 10(6) parasites. These six animals became parasitemic by 14 days PI and, along with monkey E412, carried their infants to term. These seven infants weighed significantly less at term than the infants of uninfected mothers (P = 0.0355). Symmetrical IUGR was detected by ultrasound in one fetus with an LBW of 334 g. Another LBW infant (300 g) had asymmetrical growth retardation, which has been associated with uteroplacental

  12. K13 Propeller Mutations in Plasmodium falciparum Populations in Regions of Malaria Endemicity in Vietnam from 2009 to 2016.

    PubMed

    Thuy-Nhien, Nguyen; Tuyen, Nguyen Kim; Tong, Nguyen Thanh; Vy, Nguyen Tuong; Thanh, Ngo Viet; Van, Huynh Thuy; Huong-Thu, Pham; Quang, Huynh Hong; Boni, Maciej F; Dolecek, Christiane; Farrar, Jeremy; Thwaites, Guy E; Miotto, Olivo; White, Nicholas J; Hien, Tran Tinh

    2017-04-01

    The spread of artemisinin-resistant Plasmodium falciparum compromises the therapeutic efficacy of artemisinin combination therapies (ACTs) and is considered the greatest threat to current global initiatives to control and eliminate malaria. This is particularly relevant in Vietnam, where dihydroartemisinin-piperaquine (DP) is the recommended ACT for P. falciparum infection. The propeller domain gene of K13, a molecular marker of artemisinin resistance, was successfully sequenced in 1,060 P. falciparum isolates collected at 3 malaria hot spots in Vietnam between 2009 and 2016. Eight K13 propeller mutations (Thr474Ile, Tyr493His, Arg539Thr, Ile543Thr, Pro553Leu, Val568Gly, Pro574Leu, and Cys580Tyr), including several that have been validated to be artemisinin resistance markers, were found. The prevalences of K13 mutations were 29% (222/767), 6% (11/188), and 43% (45/105) in the Binh Phuoc, Ninh Thuan, and Gia Lai Provinces of Vietnam, respectively. Cys580Tyr became the dominant genotype in recent years, with 79.1% (34/43) of isolates in Binh Phuoc Province and 63% (17/27) of isolates in Gia Lai Province carrying this mutation. K13 mutations were associated with reduced ring-stage susceptibility to dihydroartemisinin (DHA) in vitro and prolonged parasite clearance in vivo An analysis of haplotypes flanking K13 suggested the presence of multiple strains with the Cys580Tyr mutation rather than a single strain expanding across the three sites.

  13. K13 Propeller Mutations in Plasmodium falciparum Populations in Regions of Malaria Endemicity in Vietnam from 2009 to 2016

    PubMed Central

    Tuyen, Nguyen Kim; Tong, Nguyen Thanh; Vy, Nguyen Tuong; Thanh, Ngo Viet; Van, Huynh Thuy; Huong-Thu, Pham; Quang, Huynh Hong; Boni, Maciej F.; Dolecek, Christiane; Farrar, Jeremy; Thwaites, Guy E.; Miotto, Olivo; White, Nicholas J.; Hien, Tran Tinh

    2017-01-01

    ABSTRACT The spread of artemisinin-resistant Plasmodium falciparum compromises the therapeutic efficacy of artemisinin combination therapies (ACTs) and is considered the greatest threat to current global initiatives to control and eliminate malaria. This is particularly relevant in Vietnam, where dihydroartemisinin-piperaquine (DP) is the recommended ACT for P. falciparum infection. The propeller domain gene of K13, a molecular marker of artemisinin resistance, was successfully sequenced in 1,060 P. falciparum isolates collected at 3 malaria hot spots in Vietnam between 2009 and 2016. Eight K13 propeller mutations (Thr474Ile, Tyr493His, Arg539Thr, Ile543Thr, Pro553Leu, Val568Gly, Pro574Leu, and Cys580Tyr), including several that have been validated to be artemisinin resistance markers, were found. The prevalences of K13 mutations were 29% (222/767), 6% (11/188), and 43% (45/105) in the Binh Phuoc, Ninh Thuan, and Gia Lai Provinces of Vietnam, respectively. Cys580Tyr became the dominant genotype in recent years, with 79.1% (34/43) of isolates in Binh Phuoc Province and 63% (17/27) of isolates in Gia Lai Province carrying this mutation. K13 mutations were associated with reduced ring-stage susceptibility to dihydroartemisinin (DHA) in vitro and prolonged parasite clearance in vivo. An analysis of haplotypes flanking K13 suggested the presence of multiple strains with the Cys580Tyr mutation rather than a single strain expanding across the three sites. PMID:28137815

  14. Plasmodium vivax gametocyte proteins, Pvs48/45 and Pvs47, induce transmission-reducing antibodies by DNA immunization.

    PubMed

    Tachibana, Mayumi; Suwanabun, Nantavadee; Kaneko, Osamu; Iriko, Hideyuki; Otsuki, Hitoshi; Sattabongkot, Jetsumon; Kaneko, Akira; Herrera, Socrates; Torii, Motomi; Tsuboi, Takafumi

    2015-04-15

    Malaria transmission-blocking vaccines (TBV) aim to interfere with the development of the malaria parasite in the mosquito vector, and thus prevent spread of transmission in a community. To date three TBV candidates have been identified in Plasmodium vivax; namely, the gametocyte/gamete protein Pvs230, and the ookinete surface proteins Pvs25 and Pvs28. The Plasmodium falciparum gametocyte/gamete stage proteins Pfs48/45 and Pfs47 have been studied as TBV candidates, and Pfs48/45 shown to induce transmission-blocking antibodies, but the candidacy of their orthologs in P. vivax, Pvs48/45 (PVX_083235) and Pvs47 (PVX_083240), for vivax TBV have not been tested. Herein we investigated whether targeting Pvs48/45 and Pvs47 can inhibit parasite transmission to mosquitoes, using P. vivax isolates obtained in Thailand. Mouse antisera directed against the products from plasmids expressing Pvs48/45 and Pvs47 detected proteins of approximately 45- and 40-kDa, respectively, in the P. vivax gametocyte lysate, by Western blot analysis under non-reducing conditions. In immunofluorescence assays Pvs48/45 was detected predominantly on the surface and Pvs47 was detected in the cytoplasm of gametocytes. Membrane feeding transmission assays demonstrated that anti-Pvs48/45 and -Pvs47 mouse sera significantly reduced the number of P. vivax oocysts developing in the mosquito midgut. Limited amino acid polymorphism of these proteins was observed among 27 P. vivax isolates obtained from Thailand, Vanuatu, and Colombia; suggesting that polymorphism may not be an impediment for the utilization of Pvs48/45 and Pvs47 as TBV antigens. In one Thai isolate we found that the fourth cysteine residue in the Pvs47 cysteine-rich domain (CRD) III (amino acid position 337) is substituted to phenylalanine. However, antibodies targeting Pvs47 CRDI-III showed a significant transmission-reducing activity against this isolate, suggesting that this substitution in Pvs47 was not critical for recognition by the

  15. Anti-Pfs25 Human Plasma Reduces Transmission of Plasmodium falciparum Isolates That Have Diverse Genetic Backgrounds

    PubMed Central

    Da, Dari F.; Dixit, Saurabh; Sattabonkot, Jetsumon; Mu, Jianbing; Abate, Luc; Ramineni, Bhanumati; Ouedraogo, Jean Bosco; MacDonald, Nicholas J.; Fay, Michael P.; Su, Xin-zhuan; Cohuet, Anna

    2013-01-01

    Pfs25 is a leading candidate for a malaria transmission-blocking vaccine whose potential has been demonstrated in a phase 1 trial with recombinant Pfs25 formulated with Montanide ISA51. Because of limited sequence polymorphism, the anti-Pfs25 antibodies induced by this vaccine are likely to have transmission-blocking or -reducing activity against most, if not all, field isolates. To test this hypothesis, we evaluated transmission-blocking activities by membrane feeding assay of anti-Pfs25 plasma from the Pfs25/ISA51 phase 1 trial against Plasmodium falciparum parasites from patients in two different geographical regions of the world, Thailand and Burkina Faso. In parallel, parasite isolates from these patients were sequenced for the Pfs25 gene and genotyped for seven microsatellites. The results indicate that despite different genetic backgrounds among parasite isolates, the Pfs25 sequences are highly conserved, with a single nonsynonymous nucleotide polymorphism detected in 1 of 41 patients in Thailand and Burkina Faso. The anti-Pfs25 immune plasma had significantly higher transmission-reducing activity against parasite isolates from the two geographical regions than the nonimmune controls (P < 0.0001). PMID:23509152

  16. Effects of mefloquine use on Plasmodium vivax multidrug resistance.

    PubMed

    Khim, Nimol; Andrianaranjaka, Voahangy; Popovici, Jean; Kim, Saorin; Ratsimbasoa, Arsene; Benedet, Christophe; Barnadas, Celine; Durand, Remy; Thellier, Marc; Legrand, Eric; Musset, Lise; Menegon, Michela; Severini, Carlo; Nour, Bakri Y M; Tichit, Magali; Bouchier, Christiane; Mercereau-Puijalon, Odile; Ménard, Didier

    2014-10-01

    Numerous studies have indicated a strong association between amplification of the multidrug resistance-1 gene and in vivo and in vitro mefloquine resistance of Plasmodium falciparum. Although falciparum infection usually is not treated with mefloquine, incorrect diagnosis, high frequency of undetected mixed infections, or relapses of P. vivax infection triggered by P. falciparum infections expose non-P. falciparum parasites to mefloquine. To assess the consequences of such unintentional treatments on P. vivax, we studied variations in number of Pvmdr-1 (PlasmoDB accession no. PVX_080100, NCBI reference sequence NC_009915.1) copies worldwide in 607 samples collected in areas with different histories of mefloquine use from residents and from travelers returning to France. Number of Pvmdr-1 copies correlated with drug use history. Treatment against P. falciparum exerts substantial collateral pressure against sympatric P. vivax, jeopardizing future use of mefloquine against P. vivax. A drug policy is needed that takes into consideration all co-endemic species of malaria parasites.

  17. Type I interferons contribute to experimental cerebral malaria development in response to sporozoite or blood-stage Plasmodium berghei ANKA.

    PubMed

    Palomo, Jennifer; Fauconnier, Mathilde; Coquard, Laurie; Gilles, Maïlys; Meme, Sandra; Szeremeta, Frederic; Fick, Lizette; Franetich, Jean-François; Jacobs, Muazzam; Togbe, Dieudonnée; Beloeil, Jean-Claude; Mazier, Dominique; Ryffel, Bernhard; Quesniaux, Valerie F J

    2013-10-01

    Cerebral malaria is a severe complication of Plasmodium falciparum infection. Although T-cell activation and type II IFN-γ are required for Plasmodium berghei ANKA (PbA)-induced murine experimental cerebral malaria (ECM), the role of type I IFN-α/β in ECM development remains unclear. Here, we address the role of the IFN-α/β pathway in ECM devel-opment in response to hepatic or blood-stage PbA infection, using mice deficient for types I or II IFN receptors. While IFN-γR1⁻/⁻ mice were fully resistant, IFNAR1⁻/⁻ mice showed delayed and partial protection to ECM after PbA infection. ECM resistance in IFN-γR1⁻/⁻ mice correlated with unaltered cerebral microcirculation and absence of ischemia, while WT and IFNAR1⁻/⁻ mice developed distinct microvascular pathologies. ECM resistance appeared to be independent of parasitemia. Instead, key mediators of ECM were attenuated in the absence of IFNAR1, including PbA-induced brain sequestration of CXCR3⁺-activated CD8⁺ T cells. This was associated with reduced expression of Granzyme B, IFN-γ, IL-12Rβ2, and T-cell-attracting chemokines CXCL9 and CXCL10 in IFNAR1⁻/⁻ mice, more so in the absence of IFN-γR1. Therefore, the type I IFN-α/β receptor pathway contributes to brain T-cell responses and microvascular pathology, although it is not as essential as IFN-γ for the development of cerebral malaria upon hepatic or blood-stage PbA infection. © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  18. Profiling Humoral Immune Responses to P. falciparum Infection with Protein Microarrays

    PubMed Central

    Doolan, Denise L.; Mu, Yunxiang; Unal, Berkay; Sundaresh, Suman; Hirst, Siddiqua; Valdez, Conrad; Randall, Arlo; Molina, Douglas; Liang, Xiaowu; Freilich, Daniel A.; Oloo, J. Aggrey; Blair, Peter L.; Aguiar, Joao C.; Baldi, Pierre; Davies, D. Huw; Felgner, Philip L.

    2010-01-01

    A complete description of the serological response following exposure of humans to complex pathogens is lacking and approaches suitable for accomplishing this are limited. Here we report, using malaria as a model, a method which elucidates the profile of antibodies that develop after natural or experimental infection or after vaccination with attenuated organisms, and which identifies immunoreactive antigens of interest for vaccine development or other applications. Expression vectors encoding 250 Plasmodium falciparum (Pf) proteins were generated by PCR/recombination cloning; the proteins were individually expressed with >90% efficiency in E. coli cell-free in vitro transcription and translation reactions, and printed directly without purification onto microarray slides. The protein microarrays were probed with human sera from one of four groups which differed in immune status: sterile immunity or no immunity against experimental challenge following vaccination with radiation-attenuated Pf sporozoites, partial immunity acquired by natural exposure, and no previous exposure to Pf. Overall, 72 highly reactive Pf antigens were identified. Proteomic features associated with immunoreactivity were identified. Importantly, antibody profiles were distinct for each donor group. Information obtained from such analyses will facilitate identifying antigens for vaccine development, dissecting the molecular basis of immunity, monitoring the outcome of whole-organism vaccine trials, and identifying immune correlates of protection. PMID:18937256

  19. Specific antibody responses against membrane proteins of erythrocytes infected by Plasmodium falciparum of individuals briefly exposed to malaria

    PubMed Central

    2010-01-01

    Background Plasmodium falciparum infections could lead to severe malaria, principally in non-immune individuals as children and travellers from countries exempted of malaria. Severe malaria is often associated with the sequestration of P. falciparum-infected erythrocytes in deep micro-vascular beds via interactions between host endothelial receptors and parasite ligands expressed on the surface of the infected erythrocyte. Although, serological responses from individuals living in endemic areas against proteins expressed at surface of the infected erythrocyte have been largely studied, seldom data are available about the specific targets of antibody response from travellers. Methods In order to characterize antigens recognized by traveller sera, a comparison of IgG immune response against membrane protein extracts from uninfected and P. falciparum-infected red blood cells (iRBC), using immunoblots, was performed between non exposed individuals (n = 31) and briefly exposed individuals (BEI) (n = 38) to malaria transmission. Results Immune profile analysis indicated that eight protein bands from iRBC were significantly detected more frequently in the BEI group. Some of these antigenic proteins were identified by an original immuno-proteomic approach. Conclusion Collectively, these data may be useful to characterize the singular serological immune response against a primary malaria infection in individuals briefly exposed to transmission. PMID:20932351

  20. A randomized, double-blind, placebo-controlled, dose-ranging trial of tafenoquine for weekly prophylaxis against Plasmodium falciparum.

    PubMed

    Hale, Braden R; Owusu-Agyei, Seth; Fryauff, David J; Koram, Kwadwo A; Adjuik, Martin; Oduro, Abraham R; Prescott, W Roy; Baird, J Kevin; Nkrumah, Francis; Ritchie, Thomas L; Franke, Eileen D; Binka, Fred N; Horton, John; Hoffman, Stephen L

    2003-03-01

    Tafenoquine is a promising new 8-aminoquinoline drug that may be useful for malaria prophylaxis in nonpregnant persons with normal glucose-6-phosphate dehydrogenase (G6PD) function. A randomized, double-blind, placebo-controlled chemoprophylaxis trial was conducted with adult residents of northern Ghana to determine the minimum effective weekly dose of tafenoquine for the prevention of infection by Plasmodium falciparum. The primary end point was a positive malaria blood smear result during the 13 weeks of study drug coverage. Relative to the placebo, all 4 tafenoquine dosages demonstrated significant protection against P. falciparum infection: for 25 mg/week, protective efficacy was 32% (95% confidence interval [CI], 20%-43%); for 50 mg/week, 84% (95% CI, 75%-91%); for 100 mg/week, 87% (95% CI, 78%-93%); and for 200 mg/week, 86% (95% CI, 76%-92%). The mefloquine dosage of 250 mg/week also demonstrated significant protection against P. falciparum infection (protective efficacy, 86%; 95% CI, 72%-93%). There was little difference between study groups in the adverse events reported, and there was no evidence of a relationship between tafenoquine dosage and reports of physical complaints or the occurrence of abnormal laboratory parameters. Tafenoquine dosages of 50, 100, and 200 mg/week were safe, well tolerated, and effective against P. falciparum infection in this study population.

  1. 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

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

    PubMed

    de Macchi, Barbarella Matos; Miranda, Farlen José Bebber; de Souza, Fernanda Silva; de Carvalho, Eulógio Carlos Queiroz; Albernaz, Antônio Peixoto; do Nascimento, José Luiz Martins; DaMatta, Renato Augusto

    2013-02-11

    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.

  3. Prevalence of PCR detectable malaria infection among febrile patients with a negative Plasmodium falciparum specific rapid diagnostic test in Zanzibar.

    PubMed

    Baltzell, Kimberly A; Shakely, Deler; Hsiang, Michelle; Kemere, Jordan; Ali, Abdullah Suleiman; Björkman, Anders; Mårtensson, Andreas; Omar, Rahila; Elfving, Kristina; Msellem, Mwinyi; Aydin-Schmidt, Berit; Rosenthal, Philip J; Greenhouse, Bryan

    2013-02-01

    We screened for malaria in 594 blood samples from febrile patients who tested negative by a Plasmodium falciparum-specific histidine-rich protein-2-based rapid diagnostic test at 12 health facilities in Zanzibar districts North A and Micheweni, from May to August 2010. Screening was with microscopy, polymerase chain reaction (PCR) targeting the cytochrome b gene (cytbPCR) of the four major human malaria species, and quantitative PCR (qPCR). The prevalence of cytbPCR-detectable malaria infection was 2% (12 of 594), including 8 P. falciparum, 3 Plasmodium malariae, and 1 Plasmodium vivax infections. Microscopy identified 4 of 8 P. falciparum infections. Parasite density as estimated by microscopy or qPCR was > 4,000 parasites/μL in 5 of 8 cytbPCR-detectable P. falciparum infections. The infections that were missed by the rapid diagnostic test represent a particular challenge in malaria elimination settings and highlight the need for more sensitive point-of-care diagnostic tools to improve case detection of all human malaria species in febrile patients.

  4. 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.

  5. 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.

  6. Plasmodium falciparum, anaemia and cognitive and educational performance among school children in an area of moderate malaria transmission: baseline results of a cluster randomized trial on the coast of Kenya

    PubMed Central

    Halliday, Katherine E; Karanja, Peris; Turner, Elizabeth L; Okello, George; Njagi, Kiambo; Dubeck, Margaret M; Allen, Elizabeth; Jukes, Matthew CH; Brooker, Simon J

    2012-01-01

    Objectives Studies have typically investigated health and educational consequences of malaria among school-aged children in areas of high malaria transmission, but few have investigated these issues in moderate transmission settings. This study investigates the patterns of and risks for Plasmodium falciparum and anaemia and their association with cognitive and education outcomes on the Kenyan coast, an area of moderate malaria transmission. Methods As part of a cluster randomised trial, a baseline cross-sectional survey assessed the prevalence of and risk factors for P. falciparum infection and anaemia and the associations between health status and measures of cognition and educational achievement. Results are presented for 2400 randomly selected children who were enrolled in the 51 intervention schools. Results The overall prevalence of P. falciparum infection and anaemia was 13.0% and 45.5%, respectively. There was marked heterogeneity in the prevalence of P. falciparum infection by school. In multivariable analysis, being male, younger age, not sleeping under a mosquito net and household crowding were adjusted risk factors for P. falciparum infection, whilst P. falciparum infection, being male and indicators of poor nutritional intake were risk factors for anaemia. No association was observed between either P. falciparum or anaemia and performance on tests of sustained attention, cognition, literacy or numeracy. Conclusion The results indicate that in this moderate malaria transmission setting, P. falciparum is strongly associated with anaemia, but there is no clear association between health status and education. Intervention studies are underway to investigate whether removing the burden of chronic asymptomatic P. falciparum and related anaemia can improve education outcomes. PMID:22950512

  7. Plasmodium falciparum, anaemia and cognitive and educational performance among school children in an area of moderate malaria transmission: baseline results of a cluster randomized trial on the coast of Kenya.

    PubMed

    Halliday, Katherine E; Karanja, Peris; Turner, Elizabeth L; Okello, George; Njagi, Kiambo; Dubeck, Margaret M; Allen, Elizabeth; Jukes, Matthew C H; Brooker, Simon J

    2012-05-01

    Studies have typically investigated health and educational consequences of malaria among school-aged children in areas of high malaria transmission, but few have investigated these issues in moderate transmission settings. This study investigates the patterns of and risks for Plasmodium falciparum and anaemia and their association with cognitive and education outcomes on the Kenyan coast, an area of moderate malaria transmission. As part of a cluster randomised trial, a baseline cross-sectional survey assessed the prevalence of and risk factors for P. falciparum infection and anaemia and the associations between health status and measures of cognition and educational achievement. Results are presented for 2400 randomly selected children who were enrolled in the 51 intervention schools. The overall prevalence of P. falciparum infection and anaemia was 13.0% and 45.5%, respectively. There was marked heterogeneity in the prevalence of P. falciparum infection by school. In multivariable analysis, being male, younger age, not sleeping under a mosquito net and household crowding were adjusted risk factors for P. falciparum infection, whilst P. falciparum infection, being male and indicators of poor nutritional intake were risk factors for anaemia. No association was observed between either P. falciparum or anaemia and performance on tests of sustained attention, cognition, literacy or numeracy. The results indicate that in this moderate malaria transmission setting, P. falciparum is strongly associated with anaemia, but there is no clear association between health status and education. Intervention studies are underway to investigate whether removing the burden of chronic asymptomatic P. falciparum and related anaemia can improve education outcomes. © 2012 Blackwell Publishing Ltd.

  8. Reduced glycerol incorporation into phospholipids contributes to impaired intra-erythrocytic growth of glycerol kinase knockout Plasmodium falciparum parasites.

    PubMed

    Naidoo, Kubendran; Coetzer, Theresa L

    2013-11-01

    Malaria is a devastating disease and Plasmodium falciparum is the most lethal parasite infecting humans. Understanding the biology of this parasite is vital in identifying potential novel drug targets. During every 48-hour intra-erythrocytic asexual replication cycle, a single parasite can produce up to 32 progeny. This extensive proliferation implies that parasites require substantial amounts of lipid precursors for membrane biogenesis. Glycerol kinase is a highly conserved enzyme that functions at the interface of lipid synthesis and carbohydrate metabolism. P. falciparum glycerol kinase catalyzes the ATP-dependent phosphorylation of glycerol to glycerol-3-phosphate, a major phospholipid precursor. The P. falciparum glycerol kinase gene was disrupted using double crossover homologous DNA recombination to generate a knockout parasite line. Southern hybridization and mRNA analysis were used to verify gene disruption. Parasite growth rates were monitored by flow cytometry. Radiolabelling studies were used to assess incorporation of glycerol into parasite phospholipids. Disruption of the P. falciparum glycerol kinase gene produced viable parasites, but their growth was significantly reduced to 56.5±1.8% when compared to wild type parasites. (14)C-glycerol incorporation into the major phospholipids of the parasite membrane, phosphatidylcholine and phosphatidylethanolamine, was 48.4±10.8% and 53.1±5.7% relative to an equivalent number of wild type parasites. P. falciparum glycerol kinase is required for optimal intra-erythrocytic asexual parasite development. Exogenous glycerol may be used as an alternative carbon source for P. falciparum phospholipid biogenesis, despite the lack of glycerol kinase to generate glycerol-3-phosphate. These studies provide new insight into glycerolipid metabolism in P. falciparum. © 2013.

  9. 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

  10. Placental histopathological changes associated with Plasmodium vivax infection during pregnancy.

    PubMed

    Souza, Rodrigo M; Ataíde, Ricardo; Dombrowski, Jamille G; Ippólito, Vanessa; Aitken, Elizabeth H; Valle, Suiane N; Álvarez, José M; Epiphanio, Sabrina; Epiphânio, Sabrina; Marinho, Claudio R F

    2013-01-01

    Histological evidence of Plasmodium in the placenta is indicative of placental malaria, a condition associated with severe outcomes for mother and child. Histological lesions found in placentas from Plasmodium-exposed women include syncytial knotting, syncytial rupture, thickening of the placental barrier, necrosis of villous tissue and intervillositis. These histological changes have been associated with P. falciparum infections, but little is known about the contribution of P. vivax to such changes. We conducted a cross-sectional study with pregnant women at delivery and assigned them to three groups according to their Plasmodium exposure during pregnancy: no Plasmodium exposure (n = 41), P. vivax exposure (n = 59) or P. falciparum exposure (n = 19). We evaluated their placentas for signs of Plasmodium and placental lesions using ten histological parameters: syncytial knotting, syncytial rupture, placental barrier thickness, villi necrosis, intervillous space area, intervillous leucocytes, intervillous mononucleates, intervillous polymorphonucleates, parasitized erythrocytes and hemozoin. Placentas from P. vivax-exposed women showed little evidence of Plasmodium or hemozoin but still exhibited more lesions than placentas from women not exposed to Plasmodium, especially when infections occurred twice or more during pregnancy. In the Brazilian state of Acre, where diagnosis and primary treatment are readily available and placental lesions occur in the absence of detected placental parasites, relying on the presence of Plasmodium in the placenta to evaluate Plasmodium-induced placental pathology is not feasible. Multivariate logistic analysis revealed that syncytial knotting (odds ratio [OR], 4.21, P = 0.045), placental barrier thickness (OR, 25.59, P = 0.021) and mononuclear cells (OR, 4.02, P = 0.046) were increased in placentas from P. vivax-exposed women when compared to women not exposed to Plasmodium during pregnancy. A vivax-score was

  11. Clinico-pathological studies of Plasmodium falciparum and Plasmodium vivax - malaria in India and Saudi Arabia.

    PubMed

    Khan, Wajihullah; Zakai, Haytham A; Umm-E-Asma

    2014-06-01

    Malaria is one of the most devastating diseases of tropical countries with clinical manifestations such as anaemia, splenomegaly, thrombocytopenia, hepatomegaly and acute renal failures. In this study, cases of thrombocytopenia and haemoglobinemia were more prominent in subjects infected with Plasmodium falciparum (Welch, 1897) than those with Plasmodium vivax (Grassi et Feletti, 1890). However, anaemia, jaundice, convulsions and acute renal failure were significantly high (3-4 times) in subjects infected with P. falciparum than those infected with P. vivax. The incidence of splenomegaly and neurological sequelae were 2 and 6 times higher in P. falciparum infections compared to the infections of P. vivax. Both in P. vivax and P. falciparum malaria, the cases of splenomegaly, jaundice and neurological sequelae were almost double in children (<10 years) compared to older patients. The liver enzymes were generally in normal range in cases of low and mild infections. However, the AST, ALT, ALP activities and serum bilirubin, creatinine, and the urea content were increased in P. falciparum and P. vivax malaria patients having high parasitaemia, confirming liver dysfunction and renal failures in few cases of severe malaria both in India and Saudi Arabia.

  12. Inherited Glutathione Reductase Deficiency and Plasmodium falciparum Malaria—A Case Study

    PubMed Central

    Rahlfs, Stefan; Schirmer, R. Heiner; van Zwieten, Rob; Roos, Dirk; Arese, Paolo; Becker, Katja

    2009-01-01

    In Plasmodium falciparum-infected red blood cells (RBCs), the flavoenzyme glutathione reductase (GR) regenerates reduced glutathione, which is essential for antioxidant defense. GR utilizes NADPH produced in the pentose phosphate shunt by glucose-6-phosphate dehydrogenase (G6PD). Thus, conditions affecting host G6PD or GR induce increased sensitivity to oxidants. Hereditary G6PD deficiency is frequent in malaria endemic areas and provides protection against severe malaria. Furthermore, GR deficiency resulting from insufficient saturation of the enzyme with its prosthetic group FAD is common. Based on these naturally occurring phenomena, GR of malaria parasites and their host cells represent attractive antimalarial drug targets. Recently we were given the opportunity to examine invasion, growth, and drug sensitivity of three P. falciparum strains (3D7, K1, and Palo Alto) in the RBCs from three homozygous individuals with total GR deficiency resulting from mutations in the apoprotein. Invasion or growth in the GR-deficient RBCs was not impaired for any of the parasite strains tested. Drug sensitivity to chloroquine, artemisinin, and methylene blue was comparable to parasites grown in GR-sufficient RBCs and sensitivity towards paraquat and sodium nitroprusside was only slightly enhanced. In contrast, membrane deposition of hemichromes as well as the opsonizing complement C3b fragments and phagocytosis were strongly increased in ring-infected RBCs of the GR-deficient individuals compared to ring-infected normal RBCs. Also, in one of the individuals, membrane-bound autologous IgGs were significantly enhanced. Thus, based on our in vitro data, GR deficiency and drug-induced GR inhibition may protect from malaria by inducing enhanced ring stage phagocytosis rather than by impairing parasite growth directly. PMID:19806191

  13. 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

  14. Optimally timing primaquine treatment to reduce Plasmodium falciparum transmission in low endemicity Thai-Myanmar border populations

    PubMed Central

    Lawpoolsri, Saranath; Klein, Eili Y; Singhasivanon, Pratap; Yimsamran, Surapon; Thanyavanich, Nipon; Maneeboonyang, Wanchai; Hungerford, Laura L; Maguire, James H; Smith, David L

    2009-01-01

    Background Effective malaria control has successfully reduced the malaria burden in many countries, but to eliminate malaria, these countries will need to further improve their control efforts. Here, a malaria control programme was critically evaluated in a very low-endemicity Thai-Myanmar border population, where early detection and prompt treatment have substantially reduced, though not ended, Plasmodium falciparum transmission, in part due to carriage of late-maturing gametocytes that remain post-treatment. To counter this effect, the WHO recommends the use of a single oral dose of primaquine along with an effective blood schizonticide. However, while the effectiveness of primaquine as a gametocidal agent is widely documented, the mismatch between primaquine's short half-life, the long-delay for gametocyte maturation and the proper timing of primaquine administration have not been studied. Methods Mathematical models were constructed to simulate 8-year surveillance data, between 1999 and 2006, of seven villages along the Thai-Myanmar border. A simple model was developed to consider primaquine pharmacokinetics and pharmacodynamics, gametocyte carriage, and infectivity. Results In these populations, transmission intensity is very low, so the P. falciparum parasite rate is strongly linked to imported malaria and to the fraction of cases not treated. Given a 3.6-day half-life of gametocyte, the estimated duration of infectiousness would be reduced by 10 days for every 10-fold reduction in initial gametocyte densities. Infectiousness from mature gametocytes would last two to four weeks and sustain some transmission, depending on the initial parasite densities, but the residual mature gametocytes could be eliminated by primaquine. Because of the short half-life of primaquine (approximately eight hours), it was immediately obvious that with early administration (within three days after an acute attack), primaquine would not be present when mature gametocytes emerged

  15. Population Dynamics and Plasmodium falciparum (Haemosporida: Plasmodiidae) Infectivity Rates for the Malaria Vector Anopheles arabiensis (Diptera: Culicidae) at Mamfene, KwaZulu-Natal, South Africa.

    PubMed

    Dandalo, Leonard C; Brooke, Basil D; Munhenga, Givemore; Lobb, Leanne N; Zikhali, Jabulani; Ngxongo, Sifiso P; Zikhali, Phineas M; Msimang, Sipho; Wood, Oliver R; Mofokeng, Mohlominyana; Misiani, Eunice; Chirwa, Tobias; Koekemoer, Lizette L

    2017-09-06

    Anopheles arabiensis (Patton; Diptera: Culicidae) is a major malaria vector in the southern African region. In South Africa, effective control of this species using indoor-based interventions is reduced owing to its tendency to rest outdoors. As South Africa moves towards malaria elimination there is a need for complementary vector control strategies. One of the methods under consideration is the use of the sterile insect technique (SIT). Key to the successful implementation of an SIT programme is prior knowledge of the size and spatial distribution of the target population. Understanding mosquito population dynamics for both males and females is critical for efficient programme implementation. It is thus necessary to use outdoor-based population monitoring tools capable of sampling both sexes of the target population. In this project mosquito surveillance and evaluation of tools capable of collecting both genders were carried out at Mamfene in northern KwaZulu-Natal Province, South Africa, during the period January 2014 to December 2015. Outdoor- and indoor-resting Anopheles mosquitoes were sampled in three sections of Mamfene over the 2-yr sampling period using modified plastic buckets, clay pots and window exit traps. Morphological and molecular techniques were used for species identifications of all samples. Wild-caught adult females were tested for Plasmodium falciparum (Welch; Haemosporida: Plasmodiidae) infectivity. Out of 1,705 mosquitoes collected, 1,259 (73.8%) and 255 (15%) were identified as members of either the Anopheles gambiae complex or Anopheles funestus group respectively. An. arabiensis was the most abundant species contributing 78.8% of identified specimens. Mosquito density was highest in summer and lowest during winter. Clay pots yielded 16.3 mosquitoes per trap compared to 10.5 for modified plastic buckets over the 2-yr sampling period. P. falciparum infection rates for An. arabiensis were 0.7% and 0.5% for 2014 and 2015, respectively

  16. Epidemiology of coinfection with soil transmitted helminths and Plasmodium falciparum among school children in Bumula District in western Kenya.

    PubMed

    Kepha, Stella; Nuwaha, Fred; Nikolay, Birgit; Gichuki, Paul; Edwards, Tansy; Allen, Elizabeth; Njenga, Sammy M; Mwandawiro, Charles S; Brooker, Simon J

    2015-06-11

    Many school children living in Africa are infected with plasmodia and helminth species and are consequently at risk of coinfection. However, the epidemiology of such coinfection and the implications of coinfection for children's health remain poorly understood. This study describes the epidemiology of Ascaris lumbricoides-Plasmodium and hookworm-Plasmodium coinfection among school children living in western Kenya and investigates the associated risk factors. As part of a randomized trial, a baseline cross-sectional survey was conducted among school children aged 5-18 years in 23 schools in Bumula District. Single stool samples were collected to screen for helminth infections using the Kato-Katz technique and malaria parasitaemia was determined from a finger prick blood sample. Demographic and anthropometric data were also collected. Overall, 46.4% of the children were infected with Plasmodium falciparum while 27.6% of the children were infected with at least one soil transmitted helminth (STH) species, with hookworm being the most common (16.8%) followed by A. lumbricoides (15.3%). Overall 14.3% of the children had STH-Plasmodium coinfection, with hookworm-Plasmodium (9.0%) coinfection being the most common. Geographical variation in the prevalence of coinfection occurred between schools. In multivariable logistic regression analysis, hookworm was positively associated with P. falciparum infection. In stratified analysis, hookworm infection was associated with increased odds of P. falciparum infection among both boys (P < 0.001) and girls (P = 0.01), whereas there was no association between A. lumbricoides and P. falciparum. These findings demonstrate STH infections are still prevalent, despite the ongoing national deworming programme in Kenya, and that malaria parasitaemia is widespread, such that coinfection occurs among a proportion of children. A subsequent trial will allow us to investigate the implications of coinfection for the risk of clinical

  17. Antibody-independent mechanisms regulate the establishment of chronic Plasmodium infection.

    PubMed

    Brugat, Thibaut; Reid, Adam James; Lin, Jing-Wen; Cunningham, Deirdre; Tumwine, Irene; Kushinga, Garikai; McLaughlin, Sarah; Spence, Philip; Böhme, Ulrike; Sanders, Mandy; Conteh, Solomon; Bushell, Ellen; Metcalf, Tom; Billker, Oliver; Duffy, Patrick E; Newbold, Chris; Berriman, Matthew; Langhorne, Jean

    2017-02-06

    Malaria is caused by parasites of the genus Plasmodium. All human-infecting Plasmodium species can establish long-lasting chronic infections(1-5), creating an infectious reservoir to sustain transmission(1,6). It is widely accepted that the maintenance of chronic infection involves evasion of adaptive immunity by antigenic variation(7). However, genes involved in this process have been identified in only two of five human-infecting species: Plasmodium falciparum and Plasmodium knowlesi. Furthermore, little is understood about the early events in the establishment of chronic infection in these species. Using a rodent model we demonstrate that from the infecting population, only a minority of parasites, expressing one of several clusters of virulence-associated pir genes, establishes a chronic infection. This process occurs in different species of parasites and in different hosts. Establishment of chronicity is independent of adaptive immunity and therefore different from the mechanism proposed for maintenance of chronic P. falciparum infections(7-9). Furthermore, we show that the proportions of parasites expressing different types of pir genes regulate the time taken to establish a chronic infection. Because pir genes are common to most, if not all, species of Plasmodium(10), this process may be a common way of regulating the establishment of chronic infections.

  18. Plasmodium falciparum Regulatory Subunit of cAMP-Dependent PKA and Anion Channel Conductance

    PubMed Central

    Merckx, Anaïs; Nivez, Marie-Paule; Bouyer, Guillaume; Alano, Pietro; Langsley, Gordon; Deitsch, Kirk; Thomas, Serge; Doerig, Christian; Egée, Stéphane

    2008-01-01

    Malaria symptoms occur during Plasmodium falciparum development into red blood cells. During this process, the parasites make substantial modifications to the host cell in order to facilitate nutrient uptake and aid in parasite metabolism. One significant alteration that is required for parasite development is the establishment of an anion channel, as part of the establishment of New Permeation Pathways (NPPs) in the red blood cell plasma membrane, and we have shown previously that one channel can be activated in uninfected cells by exogenous protein kinase A. Here, we present evidence that in P. falciparum-infected red blood cells, a cAMP pathway modulates anion conductance of the erythrocyte membrane. In patch-clamp experiments on infected erythrocytes, addition of recombinant PfPKA-R to the pipette in vitro, or overexpression of PfPKA-R in transgenic parasites lead to down-regulation of anion conductance. Moreover, this overexpressing PfPKA-R strain has a growth defect that can be restored by increasing the levels of intracellular cAMP. Our data demonstrate that the anion channel is indeed regulated by a cAMP-dependent pathway in P. falciparum-infected red blood cells. The discovery of a parasite regulatory pathway responsible for modulating anion channel activity in the membranes of P. falciparum-infected red blood cells represents an important insight into how parasites modify host cell permeation pathways. These findings may also provide an avenue for the development of new intervention strategies targeting this important anion channel and its regulation. PMID:18248092

  19. Potential for reduction of burden and local elimination of malaria by reducing Plasmodium falciparum malaria transmission: a mathematical modelling study.

    PubMed

    Griffin, Jamie T; Bhatt, Samir; Sinka, Marianne E; Gething, Peter W; Lynch, Michael; Patouillard, Edith; Shutes, Erin; Newman, Robert D; Alonso, Pedro; Cibulskis, Richard E; Ghani, Azra C

    2016-04-01

    Rapid declines in malaria prevalence, cases, and deaths have been achieved globally during the past 15 years because of improved access to first-line treatment and vector control. We aimed to assess the intervention coverage needed to achieve further gains over the next 15 years. We used a mathematical model of the transmission of Plasmodium falciparum malaria to explore the potential effect on case incidence and malaria mortality rates from 2015 to 2030 of five different intervention scenarios: remaining at the intervention coverage levels of 2011-13 (Sustain), for which coverage comprises vector control and access to treatment; two scenarios of increased coverage to 80% (Accelerate 1) and 90% (Accelerate 2), with a switch from quinine to injectable artesunate for management of severe disease and seasonal malaria chemoprevention where recommended for both Accelerate scenarios, and rectal artesunate for pre-referral treatment at the community level added to Accelerate 2; a near-term innovation scenario (Innovate), which included longer-lasting insecticidal nets and expansion of seasonal malaria chemoprevention; and a reduction in coverage to 2006-08 levels (Reverse). We did the model simulations at the first administrative level (ie, state or province) for the 80 countries with sustained stable malaria transmission in 2010, accounting for variations in baseline endemicity, seasonality in transmission, vector species, and existing intervention coverage. To calculate the cases and deaths averted, we compared the total number of each under the five scenarios between 2015 and 2030 with the predicted number in 2015, accounting for population growth. With an increase to 80% coverage, we predicted a reduction in case incidence of 21% (95% credible intervals [CrI] 19-29) and a reduction in mortality rates of 40% (27-61) by 2030 compared with 2015 levels. Acceleration to 90% coverage and expansion of treatment at the community level was predicted to reduce case incidence by

  20. Rapid onset of transmission-reducing antibodies in javanese migrants exposed to malaria in papua, indonesia.

    PubMed

    Bousema, J Teun; Roeffen, Will; van der Kolk, Mike; de Vlas, Sake J; van de Vegte-Bolmer, Marga; Bangs, Michael J; Teelen, Karina; Kurniawan, Liliana; Maguire, Jason D; Baird, J Kevin; Sauerwein, Robert W

    2006-03-01

    Transmission of Plasmodium falciparum malaria is initiated by sexual stages in the mosquito. Anti-Pfs48/45 and anti-Pfs230 sexual stage antibodies that are ingested together with parasites can reduce parasite development and subsequently malaria transmission. Acquisition of sexual stage immunity was studied in a cohort of 102 non-immune Javanese individuals migrating to hyperendemic Papua Indonesia. Seroprevalence of antibodies against Pfs48/45 and Pfs230 and functional transmission-reducing activity (TRA) were measured upon arrival and at 6, 12, and 24 months. Asexual parasitemia and gametocytemia were assessed every two weeks. The TRA and seroreactivity increased with the number of P. falciparum infections. The longitudinally sustained association between TRA and antibodies against Pfs48/45 (odds ratio [OR] = 3.74, 95% confidence interval [CI] = 1.51-9.29) and Pfs230 (OR = 3.72, 95% CI = 1.36-10.17) suggests that functional transmission reducing immunity is acquired after limited exposure to infection.

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

    PubMed

    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

    2016-02-10

    During pregnancy immunoglobulin 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.

  2. 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

  3. Phenotypic dissection of a Plasmodium-refractory strain of malaria vector Anopheles stephensi: the reduced susceptibility to P. berghei and P. yoelii.

    PubMed

    Shinzawa, Naoaki; Ishino, Tomoko; Tachibana, Mayumi; Tsuboi, Takafumi; Torii, Motomi

    2013-01-01

    Anopheline mosquitoes are the major vectors of human malaria. Parasite-mosquito interactions are a critical aspect of disease transmission and a potential target for malaria control. Current investigations into parasite-mosquito interactions frequently assume that genetically resistant and susceptible mosquitoes exist in nature. Therefore, comparisons between the Plasmodium susceptibility profiles of different mosquito species may contribute to a better understanding of vectorial capacity. Anopheles stephensi is an important malaria vector in central and southern Asia and is widely used as a laboratory model of parasite transmission due to its high susceptibility to Plasmodium infection. In the present study, we identified a rodent malaria-refractory strain of A. stephensi mysorensis (Ehime) by comparative study of infection susceptibility. A very low number of oocysts develop in Ehime mosquitoes infected with P. berghei and P. yoelii, as determined by evaluation of developed oocysts on the basal lamina. A stage-specific study revealed that this reduced susceptibility was due to the impaired formation of ookinetes of both Plasmodium species in the midgut lumen and incomplete crossing of the midgut epithelium. There were no apparent abnormalities in the exflagellation of male parasites in the ingested blood or the maturation of oocysts after the rounding up of the ookinetes. Overall, these results suggest that invasive-stage parasites are eliminated in both the midgut lumen and epithelium in Ehime mosquitoes by strain-specific factors that remain unknown. The refractory strain newly identified in this report would be an excellent study system for investigations into novel parasite-mosquito interactions in the mosquito midgut.

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

    PubMed

    Onyamboko, Marie A; Meshnick, Steven R; Fleckenstein, Lawrence; Koch, Matthew A; Atibu, Joseph; Lokomba, Victor; Douoguih, Macaya; Hemingway-Foday, Jennifer; Wesche, David; Ryder, Robert W; Bose, Carl; Wright, Linda L; Tshefu, Antoinette K; Capparelli, Edmund V

    2011-02-28

    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. 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. 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. 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. ClinicalTrials.gov: NCT00538382.

  5. 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

  6. 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

  7. Multiple Adhesive Phenotypes Linked to Rosetting Binding of Erythrocytes in Plasmodium falciparum Malaria

    PubMed Central

    Fernandez, Victor; Treutiger, Carl Johan; Nash, Gerard B.; Wahlgren, Mats

    1998-01-01

    The cerebral form of severe malaria is associated with excessive intravascular sequestration of Plasmodium falciparum-infected erythrocytes (PRBC). Retention and accumulation of PRBC may lead to occlusion of brain microvessels and direct the triggering of acute pathologic changes. Here we report that by selection, cloning, and subcloning, we have identified rare P. falciparum parasites expressing a pan-adhesive phenotype linked to erythrocyte rosetting, a previously identified correlate of cerebral malaria. Rosetting PRBC not only bound uninfected erythrocytes but also formed autoagglutinates, adhered to endothelial cells, and bound to CD36, immunoglobulins, and the blood group A antigen. The linkage of rosetting, autoagglutination, and cytoadherence involved the coexpression on a single PRBC of ligands with multiple specificities and the binding to two or more receptors on erythrocytes and to at least two other cell adhesion molecules, including a new endothelial cell receptor for P. falciparum-infected erythrocytes. Limited proteolysis that differentially cleaved the rosetting ligand PfEMP1 from the PRBC surface abrogated all the binding phenotypes of these parasites, implicating the variant antigen PfEMP1 as a carrier of multiple ligand specificities. The results encourage the further study of pan-adhesion as a potentially important parasite phenotype in the pathogenesis of severe P. falciparum malaria. PMID:9596774

  8. Cord blood dendritic cell subsets in African newborns exposed to Plasmodium falciparum in utero.

    PubMed

    Breitling, Lutz P; Fendel, Rolf; Mordmueller, Benjamin; Adegnika, Ayola A; Kremsner, Peter G; Luty, Adrian J F

    2006-10-01

    Placental Plasmodium falciparum infection affects birth outcomes and sensitizes fetal lymphocytes to parasite antigens. We assessed the influence of maternal P. falciparum infection on fetal myeloid dendritic cells (mDC) and plasmacytoid dendritic cells (pDC), analyzing the cord blood of offspring of Gabonese mothers with different infection histories. Cord blood from newborns of mothers with malarial infection at delivery had significantly more mDC than that from nonexposed newborns (P = 0.028) but mDC and pDC HLA-DR expression was unrelated to maternal infection history. Independently of these findings, cord blood mDC and pDC numbers declined significantly as a function of increasing maternal age (P = 0.029 and P = 0.033, respectively). The inducible antigen-specific interleukin-10-producing regulatory-type T-cell population that we have previously detected in cord blood of newborns with prolonged in utero exposure to P. falciparum may directly reflect the altered DC numbers in such neonates, while the maintenance of cord blood DC HLA-DR expression contrasts with that of DC from P. falciparum malaria patients.

  9. Cord Blood Dendritic Cell Subsets in African Newborns Exposed to Plasmodium falciparum In Utero

    PubMed Central

    Breitling, Lutz P.; Fendel, Rolf; Mordmueller, Benjamin; Adegnika, Ayola A.; Kremsner, Peter G.; Luty, Adrian J. F.

    2006-01-01

    Placental Plasmodium falciparum infection affects birth outcomes and sensitizes fetal lymphocytes to parasite antigens. We assessed the influence of maternal P. falciparum infection on fetal myeloid dendritic cells (mDC) and plasmacytoid dendritic cells (pDC), analyzing the cord blood of offspring of Gabonese mothers with different infection histories. Cord blood from newborns of mothers with malarial infection at delivery had significantly more mDC than that from nonexposed newborns (P = 0.028) but mDC and pDC HLA-DR expression was unrelated to maternal infection history. Independently of these findings, cord blood mDC and pDC numbers declined significantly as a function of increasing maternal age (P = 0.029 and P = 0.033, respectively). The inducible antigen-specific interleukin-10-producing regulatory-type T-cell population that we have previously detected in cord blood of newborns with prolonged in utero exposure to P. falciparum may directly reflect the altered DC numbers in such neonates, while the maintenance of cord blood DC HLA-DR expression contrasts with that of DC from P. falciparum malaria patients. PMID:16988249

  10. Pan-Plasmodium band sensitivity for Plasmodium falciparum detection in combination malaria rapid diagnostic tests and implications for clinical management.

    PubMed

    Gatton, Michelle L; Rees-Channer, Roxanne R; Glenn, Jeffrey; Barnwell, John W; Cheng, Qin; Chiodini, Peter L; Incardona, Sandra; González, Iveth J; Cunningham, Jane

    2015-03-18

    Malaria rapid diagnostic tests (RDTs) are appropriate for case management, but persistent antigenaemia is a concern for HRP2-detecting RDTs in endemic areas. It has been suggested that pan-pLDH test bands on combination RDTs could be used to distinguish persistent antigenaemia from active Plasmodium falciparum infection, however this assumes all active infections produce positive results on both bands of RDTs, an assertion that has not been demonstrated. In this study, data generated during the WHO-FIND product testing programme for malaria RDTs was reviewed to investigate the reactivity of individual test bands against P. falciparum in 18 combination RDTs. Each product was tested against multiple wild-type P. falciparum only samples. Antigen levels were measured by quantitative ELISA for HRP2, pLDH and aldolase. When tested against P. falciparum samples at 200 parasites/μL, 92% of RDTs were positive; 57% of these on both the P. falciparum and pan bands, while 43% were positive on the P. falciparum band only. There was a relationship between antigen concentration and band positivity; ≥4 ng/mL of HRP2 produced positive results in more than 95% of P. falciparum bands, while ≥45 ng/mL of pLDH was required for at least 90% of pan bands to be positive. In active P. falciparum infections it is common for combination RDTs to return a positive HRP2 band combined with a negative pan-pLDH band, and when both bands are positive, often the pan band is faint. Thus active infections could be missed if the presence of a HRP2 band in the absence of a pan band is interpreted as being caused solely by persistent antigenaemia.

  11. 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.

  12. Efficacy of Dihydroartemisinin-Piperaquine for Treatment of Uncomplicated Plasmodium falciparum and Plasmodium vivax in Cambodia, 2008 to 2010

    PubMed Central

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

    2013-01-01

    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. PMID:23208711

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

    PubMed

    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.

  14. Detection of persistent Plasmodium spp. infections in Ugandan children after artemether-lumefantrine treatment.

    PubMed

    Betson, Martha; Sousa-Figueiredo, José C; Atuhaire, Aaron; Arinaitwe, Moses; Adriko, Moses; Mwesigwa, Gerald; Nabonge, Juma; Kabatereine, Narcis B; Sutherland, Colin J; Stothard, J Russell

    2014-12-01

    During a longitudinal study investigating the dynamics of malaria in Ugandan lakeshore communities, a consistently high malaria prevalence was observed in young children despite regular treatment. To explore the short-term performance of artemether-lumefantrine (AL), a pilot investigation into parasite carriage after treatment(s) was conducted in Bukoba village. A total of 163 children (aged 2-7 years) with a positive blood film and rapid antigen test were treated with AL; only 8.7% of these had elevated axillary temperatures. On day 7 and then on day 17, 40 children (26.3%) and 33 (22.3%) were positive by microscopy, respectively. Real-time PCR analysis demonstrated that multi-species Plasmodium infections were common at baseline, with 41.1% of children positive for Plasmodium falciparum/Plasmodium malariae, 9.2% for P. falciparum/ Plasmodium ovale spp. and 8.0% for all three species. Moreover, on day 17, 39.9% of children infected with falciparum malaria at baseline were again positive for the same species, and 9.2% of those infected with P. malariae at baseline were positive for P. malariae. Here, chronic multi-species malaria infections persisted in children after AL treatment(s). Better point-of-care diagnostics for non-falciparum infections are needed, as well as further investigation of AL performance in asymptomatic individuals.

  15. Salmonellosis in Lagos, Nigeria: Incidence of Plasmodium falciparum-associated Co-infection, Patterns of Antimicrobial Resistance, and Emergence of Reduced Susceptibility to Fluoroquinolones

    PubMed Central

    Akinyemi, Kabir O.; Bamiro, Babajide S.; Coker, Akitoye O.

    2007-01-01

    The present study was undertaken to examine the status of antimicrobial resistance in Salmonella-associated diseases, by verifying possible emergence of reduced susceptibility to fluoroquinolones in Salmonella isolates and determining the incidence of Plasmodium falciparum-associated co-infection with Salmonella serotypes. Antimicrobial resistance in clinical isolates of Salmonellae was examined for a 12-month period. Four hundred and forty-one patients comprising two groups were recruited. Group A comprised 235 patients diagnosed by clinicians of having pyrexia, and group B included stool samples of 206 patients presenting with gastroenteritis. Samples were cultured and isolates identified, and drug susceptibility testing was performed using the standard methods. Of the 235 samples screened in group A, 42 Salmonella isolates and 107 Plasmodium spp. were identified. Of the 42 Salmonella isolates, 19 (45.2%) were Salmonella Typhi, 9 (21.4%) S. Enteritidis, and 7 (16.7%) each of S. Paratyphi and S. Arizonae. Plasmodium spp.-associated co-infection with Salmonellae was observed in 16 patients mostly in complicated typhoidal cases and S. Enteritidis-associated bacteraemia. Fiftty-three of the 206 stool samples from group B patients were confirmed positive for bacterial pathogens, made up of 35 Salmonella and 18 Shigella isolates. Of the Salmonella isolates, 18 (51.4%) were S. Enteritidis, 11 (31.4%) S. Arizonae, 4 (11.4%) S. Paratyphi, and 2 (5.7%) S. Typhi. There was no statistically significant difference (p<0.01) in antimicrobial resistance patterns exhibited among typhoidal Salmonellae isolated in 2000 and 2005. A similar trend in resistance was recorded for non-typhoidal Salmonellae (p<0.05). For the first time in Lagos, Nigeria, Salmonella isolates (10–18%) with reduced susceptibility to both ciprofloxacin and ofloxacin at MIC50 and MIC90 values of 0.015 and 0.03 μg/mL respectively were found. Despite this development, ciprofloxacin and ofloxacin remain the

  16. Systematic review of current and emerging strategies for reducing morbidity from malaria in sickle cell disease.

    PubMed

    Aneni, Ehimen C; Hamer, Davidson H; Gill, Christopher J

    2013-03-01

    Sickle cell disease (SCD) is a chronic debilitating disorder affecting erythrocytes, which is especially prevalent throughout Sub-Saharan Africa and among individuals of African descent. Because malaria is thought to be a significant cause of morbidity and mortality in patients with SCD, malaria chemoprophylaxis is often recommended for these patients. In SCD, malaria chemoprophylaxis reduces malaria parasite count, anaemia and the need for blood transfusion, and improves clinical outcomes. However, the effectiveness of malaria chemoprophylaxis in the setting of SCD is based on a few studies conducted prior to the emergence of widespread antimalarial drug resistance. Consequently, it is uncertain what the optimal strategy for managing patients with SCD in malarious areas should be. Despite the widespread use of hydroxyurea in non-malarious regions, little is known about its effect in malaria-endemic areas or on malaria-related outcomes. On the one hand, hydroxyurea upregulates intercellular cell adhesion molecule 1 (ICAM-1), the cell surface receptor for adhesion of Plasmodium falciparum-infected erythrocytes, and theoretically, it could enhance parasite replication. On the other hand, hydroxyurea increases levels of foetal haemoglobin, which is protective against malaria. We explore what is currently known about the interactions between SCD and malaria and review the published literature on the efficacy of malaria chemoprophylaxis in SCD. We also consider alternative strategies, including hydroxyurea, in the reduction of malaria-associated morbidity and mortality in patients with SCD.

  17. Plasmodium immunomics.

    PubMed

    Doolan, Denise L

    2011-01-01

    The Plasmodium parasite, the causative agent of malaria, is an excellent model for immunomic-based approaches to vaccine development. The Plasmodium parasite has a complex life cycle with multiple stages and stage-specific expression of ∼5300 putative proteins. No malaria vaccine has yet been licensed. Many believe that an effective vaccine will need to target several antigens and multiple stages, and will require the generation of both antibody and cellular immune responses. Vaccine efforts to date have been stage-specific and based on only a very limited number of proteins representing <0.5% of the genome. The recent availability of comprehensive genomic, proteomic and transcriptomic datasets from human and selected non-human primate and rodent malarias provide a foundation to exploit for vaccine development. This information can be mined to identify promising vaccine candidate antigens, by proteome-wide screening of antibody and T cell reactivity using specimens from individuals exposed to malaria and technology platforms such as protein arrays, high throughput protein production and epitope prediction algorithms. Such antigens could be incorporated into a rational vaccine development process that targets specific stages of the Plasmodium parasite life cycle with immune responses implicated in parasite elimination and control. Immunomic approaches which enable the selection of the best possible targets by prioritising antigens according to clinically relevant criteria may overcome the problem of poorly immunogenic, poorly protective vaccines that has plagued malaria vaccine developers for the past 25 years. Herein, current progress and perspectives regarding Plasmodium immunomics are reviewed.

  18. MAD 20 alleles of merozoite surface protein-1 (msp-1) are associated with severe Plasmodium falciparum malaria in Pakistan.

    PubMed

    Ghanchi, Najia Karim; Hasan, Zahra; Islam, Muniba; Beg, Mohammad Asim

    2015-04-01

    Various factors determine the outcome of Plasmodium falciparum infection such as parasite load, sequestration, adhesion molecules, and immune mediators. P. falciparum merozoite surface protein-1 (msp-1) and msp-2 genotypes were also found associated with severe disease. We investigated the association between msp-1 and msp-2 genotypes in patients with uncomplicated malaria (UM) and severe malaria (SM). Twenty-two malaria patients with microscopy-confirmed P. falciparum infection and eight healthy endemic controls were selected for analysis. Nested polymerase chain reaction (PCR) was used to identify P. falciparum genotypes. The plasma concentration of cytokines [tumor necrosis factor-alpha (TNF-α), interleukin-6 (IL-6), and interferon-gamma (IFN-γ)] and chemokines [chemokine (C-X-C motif) ligand 9 (CXCL9) and CXCL10] were evaluated using enzyme-linked immunosorbent assay (ELISA). TNF-α levels were significantly higher in both UM (389 pg/mL, p = 0.020) and SM (771 pg/mL, p = 0.004) compared with healthy controls, while they were greater in SM (p = 0.012) as compared to UM. CXCL9 levels were significantly raised in SM as compared to UM and negative controls (NCs). CXCL10 levels were raised in UM (550 pg/mL, p = 0.001) and SM (1480 pg/mL, p = 0.01) as compared with NCs. Increased levels of IL-6 were found in patients carrying the FC27 allelic type of msp-2. A higher prevalence of MAD 20 and K1 msp-1 alleles was observed in the SM group compared to UM. Overall, a greater prevalence of MAD 20 alleles and increased serum TNF-α and CXCL9 levels were associated with severe outcome in malaria. Understanding the diversity of malaria genotypes is important for predicting disease-related outcomes of P. falciparum infection in endemic areas. Copyright © 2014. Published by Elsevier B.V.

  19. 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.

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

    PubMed Central

    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

    2014-01-01

    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. PMID:25059846

  1. Impact of Plasmodium falciparum Coinfection on Longitudinal Epstein-Barr Virus Kinetics in Kenyan Children.

    PubMed

    Reynaldi, Arnold; Schlub, Timothy E; Chelimo, Kiprotich; Sumba, Peter Odada; Piriou, Erwan; Ogolla, Sidney; Moormann, Ann M; Rochford, Rosemary; Davenport, Miles P

    2016-03-15

    Endemic Burkitt lymphoma is associated with Epstein-Barr virus (EBV) and Plasmodium falciparum coinfection, although how P. falciparum exposure affects the dynamics of EBV infection is unclear. We have used a modeling approach to study EBV infection kinetics in a longitudinal cohort of children living in regions of high and low malaria transmission in Kenya. Residence in an area of high malaria transmission was associated with a higher rate of EBV expansion during primary EBV infection in infants and during subsequent episodes of EBV DNA detection, as well as with longer episodes of EBV DNA detection and shorter intervals between subsequent episodes of EBV DNA detection. In addition, we found that concurrent P. falciparum parasitemia also increases the likelihood of the first and subsequent peaks of EBV in peripheral blood. This suggests that P. falciparum infection is associated with increased EBV growth and contributes to endemic Burkitt lymphoma pathogenesis.

  2. Impact of Plasmodium falciparum Coinfection on Longitudinal Epstein-Barr Virus Kinetics in Kenyan Children

    PubMed Central

    Reynaldi, Arnold; Schlub, Timothy E.; Chelimo, Kiprotich; Sumba, Peter Odada; Piriou, Erwan; Ogolla, Sidney; Moormann, Ann M.; Rochford, Rosemary; Davenport, Miles P.

    2016-01-01

    Endemic Burkitt lymphoma is associated with Epstein-Barr virus (EBV) and Plasmodium falciparum coinfection, although how P. falciparum exposure affects the dynamics of EBV infection is unclear. We have used a modeling approach to study EBV infection kinetics in a longitudinal cohort of children living in regions of high and low malaria transmission in Kenya. Residence in an area of high malaria transmission was associated with a higher rate of EBV expansion during primary EBV infection in infants and during subsequent episodes of EBV DNA detection, as well as with longer episodes of EBV DNA detection and shorter intervals between subsequent episodes of EBV DNA detection. In addition, we found that concurrent P. falciparum parasitemia also increases the likelihood of the first and subsequent peaks of EBV in peripheral blood. This suggests that P. falciparum infection is associated with increased EBV growth and contributes to endemic Burkitt lymphoma pathogenesis. PMID:26531246

  3. The efficiency of sporozoite transmission in the human malarias, Plasmodium falciparum and P. vivax*

    PubMed Central

    Burkot, T. R.; Graves, P. M.; Cattan, J. A.; Wirtz, R. A.; Gibson, F. D.

    1987-01-01

    Reported are malaria sporozoite and inoculation rates over a 1-year period in eight epidemiologically defined villages of different endemicity in Madang Province, Papua New Guinea. In the study, more than 41 000 wild-caught mosquitos were analysed for Plasmodium falciparum and P. vivax sporozoites by ELISA. In a given village the entomological inoculation rates correlated strongly with the prevalences of both these malarial parasites in children. However, the prevalence of P. falciparum infections in children was much higher than that of P. vivax, despite similar inoculation rates for the two species. These data suggest that in Papua New Guinea P. falciparum is more efficiently transmitted than P. vivax from mosquito to man. The increased efficiency of transmission of P. falciparum may be due to the heavier sporozoite densities in wild-caught mosquitos naturally infected with P. falciparum sporozoites that were tenfold greater than the sporozoite densities in mosquitos infected with P. vivax. PMID:3311441

  4. 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

  5. Coma Associated with Microscopy-Diagnosed Plasmodium vivax: A Prospective Study in Papua, Indonesia

    PubMed Central

    Hardianto, Setiawan O.; Tjitra, Emiliana; Kenangalem, Enny; Sugiarto, Paulus; Price, Ric N.; Anstey, Nicholas M.

    2011-01-01

    Background Coma complicates Plasmodium falciparum infection but is uncommonly associated with P. vivax. Most series of vivax coma have been retrospective and have not utilized molecular methods to exclude mixed infections with P. falciparum. Methods We prospectively enrolled patients hospitalized in Timika, Indonesia, with a Glasgow Coma Score (GCS) ≤10 and P. vivax monoinfection on initial microscopy over a four year period. Hematological, biochemical, serological, radiological and cerebrospinal fluid (CSF) examinations were performed to identify other causes of coma. Repeat microscopy, antigen detection and polymerase chain reaction (PCR) were performed to exclude infections with other Plasmodium species. Results Of 24 patients fulfilling enrolment criteria, 5 had clear evidence for other non-malarial etiologies. PCR demonstrated 10 mixed infections and 3 P. falciparum monoinfections. 6 (25%) patients had vivax monoinfection and no apparent alternative cause, with a median GCS of 9 (range 8–10) and a median coma duration of 42 (range 36–48) hours. CSF leukocyte counts were <10/ul (n = 3); 2 of the 3 patients without CSF examination recovered with antimalarial therapy alone. One patient had a tremor on discharge consistent with a post-malarial neurological syndrome. No patient had other organ dysfunction. The only death was associated with pure P. falciparum infection by PCR. Vivax monoinfection-associated risk of coma was estimated at 1 in 29,486 clinical vivax infections with no deaths. In comparison, the risk of falciparum-associated coma was estimated at 1 in 1,276 clinical infections with an 18.5% mortality rate. Conclusions P. vivax-associated coma is rare, occurring 23 times less frequently than that seen with falciparum malaria, and is associated with a high proportion of non-malarial causes and mixed infections using PCR. The pathogenesis of coma associated with vivax malaria, particularly the role of comorbidities, is uncertain and requires

  6. Plasmodium Immunomics

    PubMed Central

    Doolan, Denise L.

    2010-01-01

    The Plasmodium parasite, the causative agent of malaria, is an excellent model for immunomic-based approaches to vaccine development. The Plasmodium parasite has a complex life cycle with multiple stages and stage-specific expression of ~ 5,300 putative proteins. No malaria vaccine has yet been licensed. Many believe that an effective vaccine will need to target several antigens and multiple stages, and will require the generation of both antibody and cellular immune responses. Vaccine efforts to date have been stage-specific and based on only a very limited number of proteins representing < 0.5% of the genome. The recent availability of comprehensive genomic, proteomic and transcriptomic datasets from human and selected non-human primate and rodent malarias provide a foundation to exploit for vaccine development. This information can be mined to identify promising vaccine candidate antigens, by proteome-wide screening of antibody and T cell reactivity using specimens from individuals exposed to malaria and technology platforms such as protein arrays, high throughput protein production and epitope prediction algorithms. Such antigens could be incorporated into a rational vaccine development process that targets specific stages of the Plasmodium parasite life cycle with immune responses implicated in parasite elimination and control. Immunomic approaches which enable the selection of the best possible targets by prioritizing antigens according to clinically relevant criteria may overcome the problem of poorly immunogenic, poorly protective vaccines that has plagued malaria vaccine developers for the past 25 years. Herein, current progress and perspectives regarding Plasmodium immunomics are reviewed. PMID:20816843

  7. Association of ABO blood group and Plasmodium falciparum malaria in Dore Bafeno Area, Southern Ethiopia.

    PubMed

    Zerihun, Tewodros; Degarege, Abraham; Erko, Berhanu

    2011-08-01

    To assess the distribution of ABO blood group and their relationship with Plasmodium falciparum (P. falciparum) malaria among febrile outpatients who sought medical attention at Dore Bafeno Health Center, Southern Ethiopia. A total of 269 febrile outpatients who visited Dore Bafeno Health Center, Southern Ethiopia, were examined for malaria and also tested for ABO blood groups in January 2010. The blood specimens were collected by finger pricking, stained with Geimsa, and examined microscopically. Positive cases of the parasitemia were counted. CareStart™ Malaria Pf/Pv Combo was also used to test the blood specimens for malaria. ABO blood groups were determined by agglutination test using ERYCLONE(®) antisera. Data on socio-demographic characteristics and treatment status of the participants were also collected. Chi-square and ANOVA tests were used to assess the difference between frequencies and means, respectively. Out of a total of 269 participants, 178 (66.2%) febrile patients were found to be infected with Plasmodium parasites, among which 146 (54.3%), 28 (10.4%), and 4 (1.5%) belonged to P. falciparum, P. vivax, and mixed infections, respectively. All febrile patients were also tested for ABO blood groups and 51.3%, 23.5%, 21.9% and 3.3% were found to be blood types of O, A, B and AB, respectively. Both total malaria infection and P. falciparum infection showed significant association with blood types (P<0.05). The proportion of A or B but not O phenotypes was higher (P<0.05) in individuals with P. falciparum as compared with non-infected individuals. The chance of having P. falciparum infection in patients with blood groups A, B and AB was 2.5, 2.5 and 3.3 times more than individuals showing blood O phenotypes, respectively. The mean P. falciparum malaria parasitaemia for blood groups A, B, AB, and O were 3 744/µL, 1 805/µL, 5 331/µL, and 1 515/µL, respectively (P<0.01). The present findings indicate that individuals of blood groups A, B and AB are

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

    PubMed Central

    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

  9. Epidemiology of Plasmodium infections in Flores Island, Indonesia using real-time PCR.

    PubMed

    Kaisar, Maria M M; Supali, Taniawati; Wiria, Aprilianto E; Hamid, Firdaus; Wammes, Linda J; Sartono, Erliyani; Luty, Adrian J F; Brienen, Eric A T; Yazdanbakhsh, Maria; van Lieshout, Lisette; Verweij, Jaco J

    2013-05-24

    DNA-based diagnostic methods have been shown to be highly sensitive and specific for the detection of malaria. An 18S-rRNA-based, real-time polymerase chain reaction (PCR) was used to determine the prevalence and intensity of Plasmodium infections on Flores Island, Indonesia. Microscopy and real-time multiplex PCR for the detection of Plasmodium species was performed on blood samples collected in a population-based study in Nangapanda Flores Island, Indonesia. A total 1,509 blood samples were analysed. Real-time PCR revealed prevalence for Plasmodium falciparum, Plasmodium vivax, and Plasmodium malariae to be 14.5%, 13.2%, and 1.9% respectively. Sub-microscopic parasitaemia were found in more than 80% of all positive cases. The prevalence of P. falciparum and P. vivax was significantly higher in subjects younger than 20 years (p ≤ 0.01). In the present study, among non-symptomatic healthy individuals, anaemia was strongly correlated with the prevalence and load of P. falciparum infections (p ≤ 0.01; p = 0.02) and with the load of P. vivax infections (p = 0.01) as detected with real-time PCR. Subjects with AB blood group tend to have a higher risk of being infected with P. falciparum and P. vivax when compared to other blood groups. The present study has shown that real-time PCR provides more insight in the epidemiology of Plasmodium infections and can be used as a monitoring tool in the battle against malaria. The unsurpassed sensitivity of real-time PCR reveals that sub microscopic infections are common in this area, which are likely to play an important role in transmission and control. Trials number ISRCTN83830814.

  10. Immunoglobulin G Subclass-Specific Responses against Plasmodium falciparum Merozoite Antigens Are Associated with Control of Parasitemia and Protection from Symptomatic Illness▿ †

    PubMed Central

    Stanisic, Danielle I.; Richards, Jack S.; McCallum, Fiona J.; Michon, Pascal; King, Christopher L.; Schoepflin, Sonja; Gilson, Paul R.; Murphy, Vincent J.; Anders, Robin F.; Mueller, Ivo; Beeson, James G.

    2009-01-01

    Substantial evidence indicates that antibodies to Plasmodium falciparum merozoite antigens play a role in protection from malaria, although the precise targets and mechanisms mediating immunity remain unclear. Different malaria antigens induce distinct immunoglobulin G (IgG) subclass responses, but the importance of different responses in protective immunity from malaria is not known and the factors determining subclass responses in vivo are poorly understood. We examined IgG and IgG subclass responses to the merozoite antigens MSP1-19 (the 19-kDa C-terminal region of merozoite surface protein 1), MSP2 (merozoite surface protein 2), and AMA-1 (apical membrane antigen 1), including different polymorphic variants of these antigens, in a longitudinal cohort of children in Papua New Guinea. IgG1 and IgG3 were the predominant subclasses of antibodies to each antigen, and all antibody responses increased in association with age and exposure without evidence of increasing polarization toward one subclass. The profiles of IgG subclasses differed somewhat for different alleles of MSP2 but not for different variants of AMA-1. Individuals did not appear to have a propensity to make a specific subclass response irrespective of the antigen. Instead, data suggest that subclass responses to each antigen are generated independently among individuals and that antigen properties, rather than host factors, are the major determinants of IgG subclass responses. High levels of AMA-1-specific IgG3 and MSP1-19-specific IgG1 were strongly predictive of a reduced risk of symptomatic malaria and high-density P. falciparum infections. However, no antibody response was significantly associated with protection from parasitization per se. Our findings have major implications for understanding human immunity and for malaria vaccine development and evaluation. PMID:19139189

  11. Mild Plasmodium falciparum Malaria following an Episode of Severe Malaria Is Associated with Induction of the Interferon Pathway in Malawian Children

    PubMed Central

    Krupka, Malkie; Seydel, Karl; Feintuch, Catherine M.; Yee, Kenny; Kim, Ryung; Lin, Chang-Yun; Calder, R. Brent; Petersen, Christine; Taylor, Terrie

    2012-01-01

    Infection with Plasmodium falciparum can lead to a range of severe to minimal symptoms, occasionally resulting in death in young children or nonimmune adults. In areas of high transmission, older children and adults generally suffer only mild or asymptomatic malaria infections and rarely develop severe disease. The immune features underlying this apparent immunity to severe disease remain elusive. To gain insight into host responses associated with severe and mild malaria, we conducted a longitudinal study of five children who first presented with severe malaria and, 1 month later, with mild malaria. Employing peripheral blood whole-genome profiling, we identified 68 genes that were associated with mild malaria compared to their expression in the severe malaria episode (paired Students t test, P < 0.05). These genes reflect the interferon (IFN) pathway and T cell biology and include IFN-induced protein transcripts 1 to 3, oligoadenylate synthetases 1 and 3, and the T cell markers cathepsin W and perforin. Gene set enrichment analysis identified Gene Ontology (GO) pathways associated with mild malaria to include the type I interferon-mediated signaling pathway (GO 0060337), T cell activation (GO 0042110), and other GO pathways representing many aspects of immune activation. In contrast, only six genes were associated with severe malaria, including thymidine kinase 1, which was recently found to be a biomarker of cerebral malaria susceptibility in the murine model, and carbonic anhydrase, reflecting the blood's abnormal acid base environment during severe disease. These data may provide potential insights to inform pathogenesis models and the development of therapeutics to reduce severe disease outcomes due to P. falciparum infection. PMID:22232187

  12. Incidence, management, and reporting of severe and fatal Plasmodium falciparum malaria in secondary and tertiary health facilities of Alipurduar, India in 2009.

    PubMed

    Sarkar, Jagannath; Shah, Naman K; Murhekar, Manoj V

    2012-09-01

    The proportion of malaria cases that are complicated and fatal are not well described in India. Alipurduar sub-division of Jalpaiguri district in West Bengal is highly endemic for malaria. We constructed a retrospective cohort of severe malaria patients admitted in the secondary and tertiary care facilities in Alipurduar to determine the incidence, assess the management, and evaluate the reporting of severe and fatal malaria. We reviewed routine surveillance data and the case records of all the malaria patients admitted in all secondary and tertiary care facilities, both public and private. We defined severe malaria cases as Plasmodium falciparum infection with clinical signs and symptoms of organ involvement in a resident of Alipurduar admitted during January to December 2009. We compared clinical and demographic characteristics of severe malaria cases that died with those who survived. We also reviewed human resources and laboratory facilities available for the treatment of severe malaria in these health facilities. During 2009, 6191 cases of P. falciparum in Alipurduar were reported to the malaria surveillance system. We identified 336 (5.4%) cases of severe malaria among which 33 (9.8%) patients died. Four malaria deaths were also recorded from primary health centres. Only 17 of the 37 (46%) total deaths recorded were reported to the routine surveillance system. Most severe cases were males (65%), aged >15 years (72%), and nearly half were admitted to secondary care hospitals (48%). In multivariate analysis, the risk factors associated with death included increased delay fever onset and hospitalization, treatment in a secondary level hospital, younger age, and multi-organ involvement. The secondary level public hospital had too few physicians and nurses for supporting severe malaria patients as well as inadequate laboratory facilities for monitoring such patients. Severe and fatal malaria continue to burden Alipurduar and record keeping in health facilities was

  13. 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

  14. 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

  15. 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

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

    PubMed

    Pal, Priya; Daniels, Brian P; Oskman, Anna; Diamond, Michael S; Klein, Robyn S; Goldberg, Daniel E

    2016-06-07

    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. Cerebral malaria is a devastating disease. Patients have high levels of the protein HRPII in their blood. We have found that endothelial cell barriers become leaky when treated with concentrations of HRPII similar to those found in patients. This result suggests that HRPII may be important in cerebral malaria. Our finding that HRPII functions by causing inflammation suggests points of intervention for therapy or vaccination against this disease. Copyright © 2016 Pal et al.

  17. Antibodies to the Plasmodium falciparum rhoptry protein RAP-2/RSP-2 in relation to anaemia in Cameroonian children.

    PubMed

    Awah, N; Balogun, H; Achidi, E; Mariuba, L A; Nogueira, P A; Orlandi, P; Troye-Blomberg, M; Gysin, J; Berzins, K

    2011-02-01

    Previous studies have implicated reactive antibodies to the low molecular weight rhoptry-associated proteins (RAP-1, RAP-2/RSP-2 and RAP-3) in erythroid cell destruction during Plasmodium falciparum infection. In this pilot study, the frequency, specificity and functional capacity of naturally acquired anti-RAP-2/RSP-2 antibodies were investigated in the sera of anaemic and nonanaemic malaria-infected Cameroonian children. All sera recognized RAP-2/RSP-2 by FACS, irrespective of the clinical status of the subjects. However, the anaemic children showed higher levels of IgG antibodies than the nonanaemic group, while both groups showed similar levels of IgM antibodies. Only few individuals had detectable levels of RAP-2/RSP-2-specific IgG1 and IgG3 subclass antibodies, while no IgG2 and IgG4 subclass antibodies were detected in these subjects. By ELISA, the anaemic group tended to show higher levels of antibodies to RAP-2/RSP-2 regarding all antibody classes tested, except for IgG4 and IgE. Unexpectedly, sera from the nonanaemic group activated complement to a greater extent than those from the anaemic group. These results need to be confirmed in extended studies but indicate that the effector functions of the RAP-2/RSP-2-reactive antibodies may be more important than their amounts. Such antibodies could play a role in both immunity and pathogenesis during P. falciparum infection.

  18. Metabolomic analysis of patient plasma yields evidence of plant-like α-linolenic acid metabolism in Plasmodium falciparum.

    PubMed

    Lakshmanan, Viswanathan; Rhee, Kyu Y; Wang, Wei; Yu, Yiting; Khafizov, Kamil; Fiser, Andras; Wu, Peng; Ndir, Omar; Mboup, Souleymane; Ndiaye, Daouda; Daily, Johanna P

    2012-07-15

    Metabolomics offers a powerful means to investigate human malaria parasite biology and host-parasite interactions at the biochemical level, and to discover novel therapeutic targets and biomarkers of infection. Here, we used an approach based on liquid chromatography and mass spectrometry to perform an untargeted metabolomic analysis of metabolite extracts from Plasmodium falciparum-infected and uninfected patient plasma samples, and from an enriched population of in vitro cultured P. falciparum-infected and uninfected erythrocytes. Statistical modeling robustly segregated infected and uninfected samples based on metabolite species with significantly different abundances. Metabolites of the α-linolenic acid (ALA) pathway, known to exist in plants but not known to exist in P. falciparum until now, were enriched in infected plasma and erythrocyte samples. In vitro labeling with (13)C-ALA showed evidence of plant-like ALA pathway intermediates in P. falciparum. Ortholog searches using ALA pathway enzyme sequences from 8 available plant genomes identified several genes in the P. falciparum genome that were predicted to potentially encode the corresponding enzymes in the hitherto unannotated P. falciparum pathway. These data suggest that our approach can be used to discover novel facets of host/malaria parasite biology in a high-throughput manner.

  19. Prospective risk of morbidity in relation to multiplicity of infection with Plasmodium falciparum in São Tomé.

    PubMed

    Müller, D A; Charlwood, J D; Felger, I; Ferreira, C; do Rosario, V; Smith, T

    2001-02-23

    The prospective risk of acute morbidity was analysed in relation to multiplicity of Plasmodium falciparum infection in 491 individuals in a peri-urban community in São Tomé. In an initial cross-sectional survey, 40.5% of individuals were recorded by microscopy as infected with P. falciparum, and by PCR 60.5%, with the maximum prevalence in children aged 5-10 years. PCR-RFLP typing of the msp-2 gene of P. falciparum found a mean of 2.4 parasite genotypes per infected person, with little age dependence in this multiplicity and a total of 43 different msp-2 alleles identified. None of these were unique for São Tomé. Study participants were encouraged to report to a project worker whenever they suffered a febrile illness. During the 3 months following the parasitological survey the recorded incidence rates decreased with increasing baseline msp-2 multiplicity, both for P. falciparum-positive episodes and for fever without parasitaemia. While this is consistent with suggestions that multiple P. falciparum infections may protect against super-infecting parasites, confounding by patterns of health service usage is an alternative explanation. The incidence of clinical malaria episodes was only a little higher in children than in adults. This weak age-dependence in clinical immunity might be a consequence of a cohort effect resulting from resurgence of the disease after the breakdown of malaria control programs in the 1980s.

  20. [Falciform anemia and Plasmodium falciparum malaria: a threat to flap survival?].

    PubMed

    Mariéthoz, S; Pittet, B; Loutan, L; Humbert, J; Montandon, D

    1999-02-01

    Plasmodium falciparum malaria, a parasitic disease, and sickle cell anemia, a hereditary disease, are two diseases affecting erythrocyte cycle, occurring with a high prevalence in tropical Africa. They may induce microthrombosis inducing vaso-occlusion, organ dysfunction and flap necrosis. During the acute phase of Plasmodium falciparum malaria, destruction of parasitized and healthy erythrocytes, release of parasite and erythrocyte material into the circulation, and secondary host reaction occur. Plasmodium falciparum infected erythrocytes also sequester in the microcirculation of vital organs and may interfere with microcirculatory flow in the flap during the postoperative period. The lower legs of homozygous sickle cell anemia patients are areas of marginal vascularity where minor abrasions become foci of inflammation. Inflammation results in decreased local oxygen tension, sickling of erythrocytes, increased blood viscosity and thrombosis with consequent ischemia, tissue breakdown and leg ulcer. Tissue transfer has become the procedure of choice for reconstruction of the lower third of the leg although flaps may become necrotic. The aim of this study is to analyse circumstances predisposing to surgical complications and to define preventive and therapeutic measures. A review of the literature will describe the current research and the new perspectives to treat sickle cell anemia, for example hydroxyurea and vasoactive substances (pentoxifylline, naftidrofuryl, buflomedil).

  1. Plasmodium falciparum and P. malariae epidemiology in a West African village.

    PubMed Central

    Boudin, C.; Robert, V.; Verhave, J. P.; Carnevale, P.; Ambroise-Thomas, P.

    1991-01-01

    Transmission of Plasmodium falciparum and P. malariae was studied in a village in Burkina Faso. Consecutive captures of mosquitos were organized twice a month over a year and the species of the mosquitos identified. Also, the prevalences and densities of Plasmodium spp. were determined every 2 months in a sample of children who lived in the village. Anopheles gambiae, A. funestus, and A. nili were the local vectors, but only the first two played a predominant role in both P. falciparum and P. malariae transmission. The parasitological sporozoite index (SI) was 4.48% for A. gambiae and 4.22% for A. funestus. The immunological SIs were higher: 5.82% of A. gambiae were infected with P. falciparum and only 0.16% with P. malariae; the corresponding proportions for A. funestus were 6.45% and 0.41%. Transmission of Plasmodium spp. by A. gambiae was important during the rainy season (July-October) and by A. funestus at the beginning of the dry season (September-November). Each child in the study village could receive about 396 P. falciparum-infected bites per year but only 22 of P. malariae. The P. falciparum parasite indices were maximum during the middle of the rainy season (August), while those for P. malariae reached a peak during the dry season (February). PMID:1677615

  2. Antibody-independent mechanisms regulate the establishment of chronic Plasmodium infection

    PubMed Central

    Lin, Jingwen; Cunningham, Deirdre; Tumwine, Irene; Kushinga, Garikai; McLaughlin, Sarah; Spence, Philip; Böhme, Ulrike; Sanders, Mandy; Conteh, Solomon; Bushell, Ellen; Metcalf, Tom; Billker, Oliver; Duffy, Patrick E.; Newbold, Chris; Berriman, Matthew; Langhorne, Jean

    2017-01-01

    Malaria is caused by parasites of the genus Plasmodium. All human-infecting Plasmodium species can establish long-lasting chronic infections1–5, creating an infectious reservoir to sustain transmission1,6. It is widely accepted that maintenance of chronic infection involves evasion of adaptive immunity by antigenic variation7. However, genes involved in this process have been identified in only two of five human-infecting species: P. falciparum and P. knowlesi. Furthermore, little is understood about the early events in establishment of chronic infection in these species. Using a rodent model we demonstrate that only a minority of parasites from among the infecting population, expressing one of several clusters of virulence-associated pir genes, establishes a chronic infection. This process occurs in different species of parasite and in different hosts. Establishment of chronicity is independent of adaptive immunity and therefore different from the mechanism proposed for maintainance of chronic P. falciparum infections7–9. Furthermore, we show that the proportions of parasites expressing different types of pir genes regulate the time taken to establish a chronic infection. Since pir genes are common to most, if not all, species of Plasmodium10, this process may be a common way of regulating the establishment of chronic infections. PMID:28165471

  3. Peripheral Blood Mononuclear Cells Derived from Grand Multigravidae Display a Distinct Cytokine Profile in Response to P. falciparum Infected Erythrocytes

    PubMed Central

    Ludlow, Louise E.; Hasang, Wina; Umbers, Alexandra J.; Forbes, Emily K.; Ome, Maria; Unger, Holger W.; Mueller, Ivo; Siba, Peter M.; Jaworowski, Anthony; Rogerson, Stephen J.

    2014-01-01

    Immunopathology of placental malaria is most significant in women in their first pregnancy especially in endemic areas, due to a lack of protective immunity to Plasmodium falciparum, which is acquired in successive pregnancies. In some studies (but not all), grand multigravidae (defined as 5 or more pregnancies, G5–7) are more susceptible to poor birth outcomes associated with malaria compared to earlier gravidities. By comparing peripheral cellular responses in primigravidae (G1), women in their second to fourth pregnancy (G2–4) and grand multigravidae we sought to identify key components of the dysregulated immune response. PBMC were exposed to CS2-infected erythrocytes (IE) opsonised with autologous plasma or unopsonised IE, and cytokine and chemokine secretion was measured. Higher levels of opsonising antibody were present in plasma derived from multigravid compared to primigravid women. Significant differences in the levels of cytokines and chemokines secreted in response to IE were observed. Less IL-10, IL-1β, IL-6 and TNF but more CXCL8, CCL8, IFNγ and CXCL10 were detected in G5–7 compared to G2–4 women. Our study provides fresh insight into the modulation of peripheral blood cell function and effects on the balance between host protection and immunopathology during placental malaria infection. PMID:24465935

  4. Plasmodium falciparum Parasites Are Killed by a Transition State Analogue of Purine Nucleoside Phosphorylase in a Primate Animal Model

    PubMed Central

    Cassera, María B.; Hazleton, Keith Z.; Merino, Emilio F.; Obaldia, Nicanor; Ho, Meng-Chiao; Murkin, Andrew S.; DePinto, Richard; Gutierrez, Jemy A.; Almo, Steven C.; Evans, Gary B.; Babu, Yarlagadda S.; Schramm, Vern L.

    2011-01-01

    Plasmodium falciparum causes most of the one million annual deaths from malaria. Drug resistance is widespread and novel agents against new targets are needed to support combination-therapy approaches promoted by the World Health Organization. Plasmodium species are purine auxotrophs. Blocking purine nucleoside phosphorylase (PNP) kills cultured parasites by purine starvation. DADMe-Immucillin-G (BCX4945) is a transition state analogue of human and Plasmodium PNPs, binding with picomolar affinity. Here, we test BCX4945 in Aotus primates, an animal model for Plasmodium falciparum infections. Oral administration of BCX4945 for seven days results in parasite clearance and recrudescence in otherwise lethal infections of P. falciparum in Aotus monkeys. The molecular action of BCX4945 is demonstrated in crystal structures of human and P. falciparum PNPs. Metabolite analysis demonstrates that PNP blockade inhibits purine salvage and polyamine synthesis in the parasites. The efficacy, oral availability, chemical stability, unique mechanism of action and low toxicity of BCX4945 demonstrate potential for combination therapies with this novel antimalarial agent. PMID:22096507

  5. Mass screening and treatment on the basis of results of a Plasmodium falciparum-specific rapid diagnostic test did not reduce malaria incidence in Zanzibar.

    PubMed

    Cook, Jackie; Xu, Weiping; Msellem, Mwinyi; Vonk, Marlotte; Bergström, Beatrice; Gosling, Roly; Al-Mafazy, Abdul-Wahid; McElroy, Peter; Molteni, Fabrizio; Abass, Ali K; Garimo, Issa; Ramsan, Mahdi; Ali, Abdullah; Mårtensson, Andreas; Björkman, Anders

    2015-05-01

    Seasonal increases in malaria continue in hot spots in Zanzibar. Mass screening and treatment (MSAT) may help reduce the reservoir of infection; however, it is unclear whether rapid diagnostic tests (RDTs) detect a sufficient proportion of low-density infections to influence subsequent transmission. Two rounds of MSAT using Plasmodium falciparum-specific RDT were conducted in 5 hot spots (population, 12 000) in Zanzibar in 2012. In parallel, blood samples were collected on filter paper for polymerase chain reaction (PCR) analyses. Data on confirmed malarial parasite infections from health facilities in intervention and hot spot control areas were monitored as proxy for malaria transmission. Approximately 64% of the population (7859) were screened at least once. P. falciparum prevalence, as measured by RDT, was 0.2% (95% confidence interval [CI], .1%-.3%) in both rounds, compared with PCR measured prevalences (for all species) of 2.5% (95% CI, 2.1%-2.9%) and 3.8% (95% CI, 3.2%-4.4%) in rounds 1 and 2, respectively. Two fifths (40%) of infections detected by PCR included non-falciparum species. Treatment of RDT-positive individuals (4% of the PCR-detected parasite carriers) did not reduce subsequent malaria incidence, compared with control areas. Highly sensitive point-of-care diagnostic tools for detection of all human malaria species are needed to make MSAT an effective strategy in settings where malaria elimination programs are in the pre-elimination phase. © The Author 2014. Published by Oxford University Press on behalf of the Infectious Diseases Society of America. All rights reserved. For Permissions, please e-mail: journals.permissions@oup.com.

  6. Plasmodium falciparum histidine-rich protein II causes vascular leakage and exacerbates experimental cerebral malaria in mice.

    PubMed

    Pal, Priya; Balaban, Amanda E; Diamond, Michael S; Sinnis, Photini; Klein, Robyn S; Goldberg, Daniel E

    2017-01-01

    A devastating complication of Plasmodium falciparum infection is cerebral malaria, in which vascular leakage and cerebral swelling lead to coma and often death. P. falciparum produces a protein called histidine-rich protein II (HRPII) that accumulates to high levels in the bloodstream of patients and serves as a diagnostic and prognostic marker for falciparum malaria. Using a human cerebral microvascular endothelial barrier model, we previously found that HRPII activates the endothelial cell inflammasome, resulting in decreased integrity of tight junctions and increased endothelial barrier permeability. Here, we report that intravenous administration of HRPII induced blood-brain barrier leakage in uninfected mice. Furthermore, HRPII infusion in P. berghei-infected mice increased early mortality from experimental cerebral malaria. These data support the hypothesis that HRPII is a virulence factor that contributes to cerebral malaria by compromising the integrity of the blood-brain barrier.

  7. Experimental infection of the olive baboon (Paplio anubis) with Plasmodium knowlesi: severe disease accompanied by cerebral involvement.

    PubMed

    Ozwara, Hastings; Langermans, Jan A M; Maamun, Jenneby; Farah, Idle O; Yole, Dorcas S; Mwenda, Jason M; Weiler, Horst; Thomas, Alan W

    2003-08-01

    Experimental systems that model some of the complex interactions between parasite and host can be extremely valuable in identifying and developing new prophylactics and therapeutics against human diseases. Because primates have similar immune systems to humans, we have characterized a baboon model for understanding host response to Plasmodium knowlesi. Ten intact olive baboons (Papio anubis) of either sex were experimentally infected with P. knowlesi H strain erythrocytic parasites. The infection in these baboons was either acute or chronic. Animals with acute infection developed multiple system organ dysfunction and cerebral involvement. In chronically infected animals, only the spleen was moderately enlarged. The P. knowlesi parasitemia profile in baboons and rhesus monkeys was comparable. However, some clinical symptoms of the baboons and P. falciparum-infected humans were similar. These studies demonstrate for the first time that P. anubis is a suitable host for P. knowlesi for studying clinical symptoms and pathology.

  8. 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.

  9. 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

  10. Plasmodium falciparum Histones Induce Endothelial Proinflammatory Response and Barrier Dysfunction

    PubMed Central

    Gillrie, Mark R.; Lee, Kristine; Gowda, D. Channe; Davis, Shevaun P.; Monestier, Marc; Cui, Liwang; Hien, Tran Tinh; Day, Nicholas P.J.; Ho, May

    2012-01-01

    Plasmodium falciparum is a protozoan parasite of human erythrocytes that causes the most severe form of malaria. Severe P. falciparum infection is associated with endothelial activation and permeability, which are important determinants of the outcome of the infection. How endothelial cells become activated is not fully understood, particularly with regard to the effects of parasite subcomponents. We demonstrated that P. falciparum histones extracted from merozoites (HeH) directly stimulated the production of IL-8 and other inflammatory mediators by primary human dermal microvascular endothelial cells through a signaling pathway that involves Src family kinases and p38 MAPK. The stimulatory effect of HeH and recombinant P. falciparum H3 (PfH3) was abrogated by histone-specific antibodies. The release of nuclear contents on rupture of infected erythrocytes was captured by live cell imaging and confirmed by detecting nucleosomes in the supernatants of parasite cultures. HeH and recombinant parasite histones also induced endothelial permeability through a charge-dependent mechanism that resulted in disruption of junctional protein expression and cell death. Recombinant human activated protein C cleaved HeH and PfH3 and abrogated their proinflammatory effects. Circulating nucleosomes of both human and parasite origin were detected in the plasma of patients with falciparum malaria and correlated positively with disease severity. These results support a pathogenic role for both host- and pathogen-derived histones in P. falciparum-caused malaria. PMID:22260922

  11. 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.

  12. Functional Characterization of the Plasmodium falciparum Chloroquine-Resistance Transporter (PfCRT) in Transformed Dictyostelium discoideum Vesicles

    PubMed Central

    Papakrivos, Janni; Sá, Juliana M.; Wellems, Thomas E.

    2012-01-01

    Background Chloroquine (CQ)-resistant Plasmodium falciparum malaria has been a global health catastrophe, yet much about the CQ resistance (CQR) mechanism remains unclear. Hallmarks of the CQR phenotype include reduced accumulation of protonated CQ as a weak base in the digestive vacuole of the erythrocyte-stage parasite, and chemosensitization of CQ-resistant (but not CQ-sensitive) P. falciparum by agents such as verapamil. Mutations in the P. falciparum CQR transporter (PfCRT) confer CQR; particularly important among these mutations is the charge-loss substitution K→T at position 76. Dictyostelium discoideum transformed with mutant PfCRT expresses key features of CQR including reduced drug accumulation and verapamil chemosensitization. Methodology and Findings We describe the isolation and characterization of PfCRT-transformed, hematin-free vesicles from D. discoideum cells. These vesicles permit assessments of drug accumulation, pH, and membrane potential that are difficult or impossible with hematin-containing digestive vacuoles from P. falciparum-infected erythrocytes. Mutant PfCRT-transformed D. discoideum vesicles show features of the CQR phenotype, and manipulations of vesicle membrane potential by agents including ionophores produce large changes of CQ accumulation that are dissociated from vesicular pH. PfCRT in its native or mutant form blunts the ability of valinomycin to reduce CQ accumulation in transformed vesicles and decreases the ability of K+ to reverse membrane potential hyperpolarization caused by valinomycin treatment. Conclusion Isolated vesicles from mutant-PfCRT-transformed D. discoideum exhibit features of the CQR phenotype, consistent with evidence that the drug resistance mechanism operates at the P. falciparum digestive vacuole membrane in malaria. Membrane potential apart from pH has a major effect on the PfCRT-mediated CQR phenotype of D. discoideum vesicles. These results support a model of PfCRT as an electrochemical potential

  13. Antibody response against three Plasmodium falciparum merozoite antigens in Mamuju District, West Sulawesi Province, Indonesia.

    PubMed

    Sennang, Nurhayana; Rogerson, Stephen; Wahyuni, Sitti; Yusuf, Irawan; Syafruddin, Din

    2014-09-25

    Malaria endemicity in the archipelago of Indonesia varies substantially across regions. Following the government's plan for a malaria elimination programme in Indonesia, baseline malaria surveys were conducted in Mamuju District, West Sulawesi Province, Indonesia to re-assess the malaria situation prior to the establishment of an evidence-based malaria elimination programme in the area. The present study aims to determine the antibody response to three merozoite antigens among the inhabitants of the district. Antibodies were measured following elution from filter-paper blood spots collected during cross-sectional surveys in the dry and wet season in 2010. Enzyme-linked immunosorbent assays using three merozoite antigens, MSP2, EBA175 and PfRh2a were conducted. A positivity threshold was determined by samples from unexposed individuals and the difference in antibody level against each antigen and correlation of antibody level in different age groups and seasons were statistically analysed. A total of 497 subjects, 248 in dry and 249 in wet season, aged between 0.6 and 78 years were included. The prevalence of positive antibody responses to MSP2, EBA175 and PfRh2a antigens in dry season were 27.82, 27.42 and 25.81%, respectively. In wet season, the antibody prevalences were 64.26, 64.66 and 61.45%. The antibody levels to the three antigens were all higher in older age groups and also significantly higher in the wet season. The antibody levels also correlated positively with the Plasmodium falciparum infection status of the subjects. MSP2, EBA175 and PfRh2a induce antibody responses among the subjects in Mamuju District, and the prevalence is significantly higher in wet season. The level of antibody also correlates significantly with age and malaria positivity. The overall results indicate the antigens might be used as a target for vaccines against P. falciparum infection and as markers for malaria exposure.

  14. Global Mass Spectrometry Based Metabolomics Profiling of Erythrocytes Infected with Plasmodium falciparum

    PubMed Central

    Sana, Theodore R.; Gordon, D. Benjamin; Fischer, Steven M.; Tichy, Shane E.; Kitagawa, Norton; Lai, Cindy; Gosnell, William L.; Chang, Sandra P.

    2013-01-01

    Malaria is a global infectious disease that threatens the lives of millions of people. Transcriptomics, proteomics and functional genomics studies, as well as sequencing of the Plasmodium falciparum and Homo sapiens genomes, have shed new light on this host-parasite relationship. Recent advances in accurate mass measurement mass spectrometry, sophisticated data analysis software, and availability of biological pathway databases, have converged to facilitate our global, untargeted biochemical profiling study of in vitro P. falciparum-infected (IRBC) and uninfected (NRBC) erythrocytes. In order to expand the number of detectable metabolites, several key analytical steps in our workflows were optimized. Untargeted and targeted data mining resulted in detection of over one thousand features or chemical entities. Untargeted features were annotated via matching to the METLIN metabolite database. For targeted data mining, we queried the data using a compound database derived from a metabolic reconstruction of the P. falciparum genome. In total, over one hundred and fifty differential annotated metabolites were observed. To corroborate the representation of known biochemical pathways from our data, an inferential pathway analysis strategy was used to map annotated metabolites onto the BioCyc pathway collection. This hypothesis-generating approach resulted in over-representation of many metabolites onto several IRBC pathways, most prominently glycolysis. In addition, components of the “branched” TCA cycle, partial urea cycle, and nucleotide, amino acid, chorismate, sphingolipid and fatty acid metabolism were found to be altered in IRBCs. Interestingly, we detected and confirmed elevated levels for cyclic ADP ribose and phosphoribosyl AMP in IRBCs, a novel observation. These metabolites may play a role in regulating the release of intracellular Ca2+ during P. falciparum infection. Our results support a strategy of global metabolite profiling by untargeted data

  15. 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

  16. 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

  17. High Plasmodium falciparum longitudinal prevalence is associated with high multiclonality and reduced clinical malaria risk in a seasonal transmission area of Mali.

    PubMed

    Adomako-Ankomah, Yaw; Chenoweth, Matthew S; Durfee, Katelyn; Doumbia, Saibou; Konate, Drissa; Doumbouya, Mory; Keita, Abdoul S; Nikolaeva, Daria; Tullo, Gregory S; Anderson, Jennifer M; Fairhurst, Rick M; Daniels, Rachel; Volkman, Sarah K; Diakite, Mahamadou; Miura, Kazutoyo; Long, Carole A

    2017-01-01

    The effects of persistent Plasmodium falciparum (Pf) infection and multiclonality on subsequent risk of clinical malaria have been reported, but the relationship between these 2 parameters and their relative impacts on the clinical outcome of infection are not understood. A longitudinal cohort study was conducted in a seasonal and high-transmission area of Mali, in which 500 subjects aged 1-65 years were followed for 1 year. Blood samples were collected every 2 weeks, and incident malaria cases were diagnosed and treated. Pf infection in each individual at each time point was assessed by species-specific nested-PCR, and Pf longitudinal prevalence per person (PfLP, proportion of Pf-positive samples over 1 year) was calculated. Multiclonality of Pf infection was measured using a 24-SNP DNA barcoding assay at 4 time-points (two in wet season, and two in dry season) over one year. PfLP was positively correlated with multiclonality at each time point (all r≥0.36; all P≤0.011). When host factors (e.g., age, gender), PfLP, and multiclonality (at the beginning of the transmission season) were analyzed together, only increasing age and high PfLP were associated with reduced clinical malaria occurrence or reduced number of malaria episodes (for both outcomes, P<0.001 for age, and P = 0.005 for PfLP). When age, PfLP and baseline Pf positivity were analyzed together, the effect of high PfLP remained significant even after adjusting for the other two factors (P = 0.001 for malaria occurrence and P<0.001 for number of episodes). In addition to host age and baseline Pf positivity, both of which have been reported as important modifiers of clinical malaria risk, our results demonstrate that persistent parasite carriage, but not baseline multiclonality, is associated with reduced risk of clinical disease in this population. Our study emphasizes the importance of considering repeated parasite exposure in future studies that evaluate clinical malaria risk.

  18. High Plasmodium falciparum longitudinal prevalence is associated with high multiclonality and reduced clinical malaria risk in a seasonal transmission area of Mali

    PubMed Central

    Adomako-Ankomah, Yaw; Chenoweth, Matthew S.; Durfee, Katelyn; Doumbia, Saibou; Konate, Drissa; Doumbouya, Mory; Keita, Abdoul S.; Nikolaeva, Daria; Tullo, Gregory S.; Anderson, Jennifer M.; Fairhurst, Rick M.; Daniels, Rachel; Volkman, Sarah K.; Diakite, Mahamadou; Long, Carole A.

    2017-01-01

    The effects of persistent Plasmodium falciparum (Pf) infection and multiclonality on subsequent risk of clinical malaria have been reported, but the relationship between these 2 parameters and their relative impacts on the clinical outcome of infection are not understood. A longitudinal cohort study was conducted in a seasonal and high-transmission area of Mali, in which 500 subjects aged 1–65 years were followed for 1 year. Blood samples were collected every 2 weeks, and incident malaria cases were diagnosed and treated. Pf infection in each individual at each time point was assessed by species-specific nested-PCR, and Pf longitudinal prevalence per person (PfLP, proportion of Pf-positive samples over 1 year) was calculated. Multiclonality of Pf infection was measured using a 24-SNP DNA barcoding assay at 4 time-points (two in wet season, and two in dry season) over one year. PfLP was positively correlated with multiclonality at each time point (all r≥0.36; all P≤0.011). When host factors (e.g., age, gender), PfLP, and multiclonality (at the beginning of the transmission season) were analyzed together, only increasing age and high PfLP were associated with reduced clinical malaria occurrence or reduced number of malaria episodes (for both outcomes, P<0.001 for age, and P = 0.005 for PfLP). When age, PfLP and baseline Pf positivity were analyzed together, the effect of high PfLP remained significant even after adjusting for the other two factors (P = 0.001 for malaria occurrence and P<0.001 for number of episodes). In addition to host age and baseline Pf positivity, both of which have been reported as important modifiers of clinical malaria risk, our results demonstrate that persistent parasite carriage, but not baseline multiclonality, is associated with reduced risk of clinical disease in this population. Our study emphasizes the importance of considering repeated parasite exposure in future studies that evaluate clinical malaria risk. PMID:28158202

  19. Clustered local transmission and asymptomatic Plasmodium falciparum and Plasmodium vivax malaria infections in a recently emerged, hypoendemic Peruvian Amazon community

    PubMed Central

    Branch, OraLee; Casapia, W Martin; Gamboa, Dionicia V; Hernandez, Jean N; Alava, Freddy F; Roncal, Norma; Alvarez, Eugenia; Perez, Enrique J; Gotuzzo, Eduardo

    2005-01-01

    Background There is a low incidence of malaria in Iquitos, Peru, suburbs detected by passive case-detection. This low incidence might be attributable to infections clustered in some households/regions and/or undetected asymptomatic infections. Methods Passive case-detection (PCD) during the malaria season (February-July) and an active case-detection (ACD) community-wide survey (March) surveyed 1,907 persons. Each month, April-July, 100-metre at-risk zones were defined by location of Plasmodium falciparum infections in the previous month. Longitudinal ACD and PCD (ACP+PCD) occurred within at-risk zones, where 137 houses (573 persons) were randomly selected as sentinels, each with one month of weekly active sampling. Entomological captures were conducted in the sentinel houses. Results The PCD incidence was 0.03 P. falciparum and 0.22 Plasmodium vivax infections/person/malaria-season. However, the ACD+PCD prevalence was 0.13 and 0.39, respectively. One explanation for this 4.33 and 1.77-fold increase, respectively, was infection clustering within at-risk zones and contiguous households. Clustering makes PCD, generalized to the entire population, artificially low. Another attributable-factor was that only 41% and 24% of the P. falciparum and P. vivax infections were associated with fever and 80% of the asymptomatic infections had low-density or absent parasitaemias the following week. After accounting for asymptomatic infections, a 2.6-fold increase in ACD+PCD versus PCD was attributable to clustered transmission in at-risk zones. Conclusion Even in low transmission, there are frequent highly-clustered asymptomatic infections, making PCD an inadequate measure of incidence. These findings support a strategy of concentrating ACD and insecticide campaigns in houses adjacent to houses were malaria was detected one month prior. PMID:15975146

  20. 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

  1. Infection Intensity-Dependent Responses of Anopheles gambiae to the African Malaria Parasite Plasmodium falciparum ▿ †

    PubMed Central

    Mendes, Antonio M.; Awono-Ambene, Parfait H.; Nsango, Sandrine E.; Cohuet, Anna; Fontenille, Didier; Kafatos, Fotis C.; Christophides, George K.; Morlais, Isabelle; Vlachou, Dina

    2011-01-01

    Malaria remains a devastating disease despite efforts at control and prevention. Extensive studies using mostly rodent infection models reveal that successful Plasmodium parasite transmission by the African mosquito vector Anopheles gambiae depends on finely tuned vector-parasite interactions. Here we investigate the transcriptional response of A. gambiae to geographically related Plasmodium falciparum populations at various infection intensities and different infection stages. These responses are compared with those of mosquitoes infected with the rodent parasite Plasmodium berghei. We demonstrate that mosquito responses are largely dependent on the intensity of infection. A major transcriptional suppression of genes involved in the regulation of midgut homeostasis is detected in low-intensity P. falciparum infections, the most common type of infection in Africa. Importantly, genes transcriptionally induced during these infections tend to be phylogenetically unique to A. gambiae. These data suggest that coadaptation between vectors and parasites may act to minimize the impact of infection on mosquito fitness by selectively suppressing specific functional classes of genes. RNA interference (RNAi)-mediated gene silencing provides initial evidence for important roles of the mosquito G protein-coupled receptors (GPCRs) in controlling infection intensity-dependent antiparasitic responses. PMID:21844236

  2. AP-1/Fos-TGase2 Axis Mediates Wounding-induced Plasmodium falciparum Killing in Anopheles gambiae*

    PubMed Central

    Nsango, Sandrine E.; Pompon, Julien; Xie, Ting; Rademacher, Annika; Fraiture, Malou; Thoma, Martine; Awono-Ambene, Parfait H.; Moyou, Roger S.; Morlais, Isabelle; Levashina, Elena A.

    2013-01-01

    Anopheline mosquitoes are the only vectors of human malaria worldwide. It is now widely accepted that mosquito immune responses play a crucial role in restricting Plasmodium development within the vector; therefore, further dissection of the molecular mechanisms underlying these processes should inform new vector control strategies urgently needed to roll back the disease. Here, using genome-wide transcriptional profiling, bioinformatics, and functional gene analysis, we identify a new axis of mosquito resistance to monoclonal Plasmodium falciparum infections that includes the AP-1 transcription factor Fos and the transglutaminase 2 (TGase2), a cross-linking enzyme with known roles in wound responses. We demonstrate that Fos regulates induction of TGase2 expression after wounding but does not affect expression of the components of the well characterized complement-like system. Silencing of Fos or of TGase2 aborts the wounding-induced mosquito killing of P. falciparum. These results reveal multiple signaling pathways that are required for efficient Plasmodium killing in Anopheles gambiae. PMID:23592781

  3. 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

  4. Baculovirus-expressed Plasmodium reichenowi EBA-140 merozoite ligand is host specific.

    PubMed

    Zerka, Agata; Olechwier, Agnieszka; Rydzak, Joanna; Kaczmarek, Radoslaw; Jaskiewicz, Ewa

    2016-12-01

    Plasmodium reichenowi, an ape malaria parasite is morphologically identical and genetically similar to Plasmodium falciparum, infects chimpanzees but not humans. Genomic studies revealed that all primate malaria parasites belong to Laverania subgenus. Laverania parasites exhibit strict host specificity, but the molecular mechanisms underlying these host restrictions remain unexplained. Plasmodium merozoites express multiple binding ligands that recognize specific receptors on erythrocytes, including micronemal proteins belonging to P. falciparum EBL family. It was shown that erythrocyte binding antigen-175 (EBA-175), erythrocyte binding ligand-1 (EBL-1), erythrocyte binding antigen-140 (EBA-140) recognize erythrocyte surface sialoglycoproteins - glycophorins A, B, C, respectively. EBA-140 merozoite ligand hijacks glycophorin C (GPC), a minor erythrocyte sialoglycoprotein, to invade the erythrocyte through an alternative invasion pathway. A homolog of P. falciparum EBA-140 protein was identified in P. reichenowi. The amino acid sequences of both EBA-140 ligands are very similar, especially in the conservative erythrocyte binding region (Region II). It has been suggested that evolutionary changes in the sequence of EBL proteins may be associated with Plasmodium host restriction. In this study we obtained, for the first time, the recombinant P. reichenowi EBA-140 ligand Region II using baculovirus expression vector system. We show that the ape EBA-140 Region II is host specific and binds to chimpanzee erythrocytes in the dose and sialic acid dependent manner. Further identification of the erythrocyte receptor for this ape ligand is of great interests, since it may reveal the molecular basis of host restriction of both P. reichenowi and its deadliest human counterpart, P. falciparum. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

  5. 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

  6. Natural acquisition of immunity to Plasmodium vivax: epidemiological observations and potential targets.

    PubMed

    Mueller, Ivo; Galinski, Mary R; Tsuboi, Takafumi; Arevalo-Herrera, Myriam; Collins, William E; King, Christopher L

    2013-01-01

    Population studies show that individuals acquire immunity to Plasmodium vivax more quickly than Plasmodium falciparum irrespective of overall transmission intensity, resulting in the peak burden of P. vivax malaria in younger age groups. Similarly, actively induced P. vivax infections in malaria therapy patients resulted in faster and generally more strain-transcending acquisition of immunity than P. falciparum infections. The mechanisms behind the more rapid acquisition of immunity to P. vivax are poorly understood. Natural acquired immune responses to P. vivax target both pre-erythrocytic and blood-stage antigens and include humoral and cellular components. To date, only a few studies have investigated the association of these immune responses with protection, with most studies focussing on a few merozoite antigens (such as the Pv Duffy binding protein (PvDBP), the Pv reticulocyte binding proteins (PvRBPs), or the Pv merozoite surface proteins (PvMSP1, 3 & 9)) or the circumsporozoite protein (PvCSP). Naturally acquired transmission-blocking (TB) immunity (TBI) was also found in several populations. Although limited, these data support the premise that developing a multi-stage P. vivax vaccine may be feasible and is worth pursuing. Copyright © 2013 Elsevier Ltd. All rights reserved.

  7. Enhanced detection of gametocytes by magnetic deposition microscopy predicts higher potential for Plasmodium falciparum transmission

    PubMed Central

    Karl, Stephan; David, Makindi; Moore, Lee; Grimberg, Brian T; Michon, Pascal; Mueller, Ivo; Zborowski, Maciej; Zimmerman, Peter A

    2008-01-01

    Background Aggregated haemozoin crystals within malaria-infected erythrocytes confer susceptibility of parasitized cells to a magnetic field. Here the utility of this method for diagnosis of human malaria is evaluated in a malaria-endemic region of Papua New Guinea (PNG). Methods and findings Individuals with Plasmodium falciparum malaria symptoms (n = 55) provided samples for conventional blood smear (CBS) and magnetic deposition microscopy (MDM) diagnosis. Standard Giemsa staining and light microscopy was performed to evaluate all preparations. Plasmodium falciparum parasitaemia observed on MDM slides was consistently higher than parasitaemia observed by (CBS) for ring (CBS = 2.6 vs. MDM = 3.4%; t-test P-value = 0.13), trophozoite (CBS = 0.5 vs. MDM = 1.6%; t-test P-value = 0.01), schizont (CBS = 0.003 vs. MDM = 0.1%; t-test P-value = 0.08) and gametocyte (CBS = 0.001 vs. MDM = 0.4%; t-test P-value = 0.0002) parasitaemias. Gametocyte prevalence determined by CBS compared to MDM increased from 7.3% to 45%, respectively. Conclusion MDM increased detection sensitivity of P. falciparum-infected, haemozoin-containing erythrocytes from infected humans while maintaining detection of ring-stage parasites. Gametocyte prevalence five-fold higher than observed by CBS suggests higher malaria transmission potential in PNG endemic sites compared to previous estimates. PMID:18439240

  8. Plasmodium falciparum-Derived Uric Acid Precipitates Induce Maturation of Dendritic Cells

    PubMed Central

    van de Hoef, Diana L.; Coppens, Isabelle; Holowka, Thomas; Ben Mamoun, Choukri; Branch, OraLee; Rodriguez, Ana

    2013-01-01

    Malaria is characterized by cyclical fevers and high levels of inflammation, and while an early inflammatory response contributes to parasite clearance, excessive and persistent inflammation can lead to severe forms of the disease. Here, we show that Plasmodium falciparum-infected erythrocytes contain uric acid precipitates in the cytoplasm of the parasitophorous vacuole, which are released when erythrocytes rupture. Uric acid precipitates are highly inflammatory molecules that are considered a danger signal for innate immunity and are the causative agent in gout. We determined that P. falciparum-derived uric acid precipitates induce maturation of human dendritic cells, increasing the expression of cell surface co-stimulatory molecules such as CD80 and CD86, while decreasing human leukocyte antigen-DR expression. In accordance with this, uric acid accounts for a significant proportion of the total stimulatory activity induced by parasite-infected erythrocytes. Moreover, the identification of uric acid precipitates in P. falciparum- and P. vivax-infected erythrocytes obtained directly from malaria patients underscores the in vivo and clinical relevance of our findings. Altogether, our data implicate uric acid precipitates as a potentially important contributor to the innate immune response to Plasmodium infection and may provide a novel target for adjunct therapies. PMID:23405174

  9. HIV Treatments Reduce Malaria Liver Stage Burden in a Non-Human Primate Model of Malaria Infection at Clinically Relevant Concentrations In Vivo

    PubMed Central

    Hobbs, Charlotte V.; Neal, Jillian; Conteh, Solomon; Donnelly, Liam; Chen, Jingyang; Marsh, Kennan; Lambert, Lynn; Orr-Gonzalez, Sachy; Hinderer, Jessica; Healy, Sara; Borkowsky, William; Penzak, Scott R.; Chakravarty, Sumana; Hoffman, Stephen L.; Duffy, Patrick E.

    2014-01-01

    We have previously shown that the HIV protease inhibitor lopinavir-ritonavir (LPV-RTV) and the antibiotic trimethoprim sulfamethoxazole (TMP-SMX) inhibit Plasmodium liver stages in rodent malarias and in vitro in P. falciparum. Since clinically relevant levels are better achieved in the non-human-primate model, and since Plasmodium knowlesi is an accepted animal model for the study of liver stages of malaria as a surrogate for P. falciparum infection, we investigated the antimalarial activity of these drugs on Plasmodium knowlesi liver stages in rhesus macaques. We demonstrate that TMP-SMX and TMP-SMX+LPV-RTV (in combination), but not LPV-RTV alone, inhibit liver stage parasite development. Because drugs that inhibit the clinically silent liver stages target parasites when they are present in lower numbers, these results may have implications for eradication efforts. PMID:24988386

  10. Identification of pyrimethamine- and chloroquine-resistant Plasmodium falciparum in Africa between 1984 and 1998: genotyping of archive blood samples.

    PubMed

    Saito-Nakano, Yumiko; Tanabe, Kazuyuki; Mita, Toshihiro

    2011-12-31

    Understanding the geographical distribution of drug resistance of Plasmodium falciparum is important for the effective treatment of malaria. Drug resistance has previously been inferred mainly from records of clinical resistance. However, clinical resistance is not always consistent with the parasite's genetic resistance. Thus, molecular identification of the parasite's drug resistance is required. In Africa, clinical resistance to pyrimethamine (Pyr) and chloroquine (CQ) was evident before 1980 but few studies investigating the genetic resistance to these drugs were conducted before the late 1990s. In this study, genotyping of genes involved in resistance to Pyr and CQ was performed using archive blood samples from Africa between 1984 and 1998. Parasite DNA was extracted from P. falciparum-infected blood smears collected from travellers returning to Japan from Africa between 1984 and 1998. Genotypes of the dihydrofolate reductase gene (dhfr) and CQ-resistance transporter gene (pfcrt) were determined by polymerase chain reaction amplification and sequencing. Genotyping of dhfr and pfcrt was successful in 59 and 80 samples, respectively. One wild-type and seven mutant dhfr genotypes were identified. Three dhfr genotypes lacking the S108N mutation (NRSI, ICSI, IRSI; amino acids at positions 51, 59, 108, and 164 with mutations underlined) were highly prevalent before 1994 but reduced after 1995, accompanied by an increase in genotypes with the S108N mutation. The dhfr IRNI genotype was first identified in Nigeria in 1991 in the present samples, and its frequency gradually increased. However, two double mutants (ICNI and NRNI), the latter of which was exclusively found in West Africa, were more frequent than the IRNI genotype. Only two pfcrt genotypes were found, the wild-type and a Southeast Asian type (CVIET; amino acids at positions 72-76 with mutations underlined). The CVIET genotype was already present as early as 1984 in Tanzania and Nigeria, and appeared

  11. Identification of pyrimethamine- and chloroquine-resistant Plasmodium falciparum in Africa between 1984 and 1998: genotyping of archive blood samples

    PubMed Central

    2011-01-01

    Background Understanding the geographical distribution of drug resistance of Plasmodium falciparum is important for the effective treatment of malaria. Drug resistance has previously been inferred mainly from records of clinical resistance. However, clinical resistance is not always consistent with the parasite's genetic resistance. Thus, molecular identification of the parasite's drug resistance is required. In Africa, clinical resistance to pyrimethamine (Pyr) and chloroquine (CQ) was evident before 1980 but few studies investigating the genetic resistance to these drugs were conducted before the late 1990s. In this study, genotyping of genes involved in resistance to Pyr and CQ was performed using archive blood samples from Africa between 1984 and 1998. Methods Parasite DNA was extracted from P. falciparum-infected blood smears collected from travellers returning to Japan from Africa between 1984 and 1998. Genotypes of the dihydrofolate reductase gene (dhfr) and CQ-resistance transporter gene (pfcrt) were determined by polymerase chain reaction amplification and sequencing. Results Genotyping of dhfr and pfcrt was successful in 59 and 80 samples, respectively. One wild-type and seven mutant dhfr genotypes were identified. Three dhfr genotypes lacking the S108N mutation (NRSI, ICSI, IRSI; amino acids at positions 51, 59, 108, and 164 with mutations underlined) were highly prevalent before 1994 but reduced after 1995, accompanied by an increase in genotypes with the S108N mutation. The dhfr IRNI genotype was first identified in Nigeria in 1991 in the present samples, and its frequency gradually increased. However, two double mutants (ICNI and NRNI), the latter of which was exclusively found in West Africa, were more frequent than the IRNI genotype. Only two pfcrt genotypes were found, the wild-type and a Southeast Asian type (CVIET; amino acids at positions 72-76 with mutations underlined). The CVIET genotype was already present as early as 1984 in Tanzania and

  12. Malaria risk factor assessment using active and passive surveillance data from Aceh Besar, Indonesia, a low endemic, malaria elimination setting with Plasmodium knowlesi, Plasmodium vivax, and Plasmodium falciparum.

    PubMed

    Herdiana, Herdiana; Cotter, Chris; Coutrier, Farah N; Zarlinda, Iska; Zelman, Brittany W; Tirta, Yusrifar Kharisma; Greenhouse, Bryan; Gosling, Roly D; Baker, Peter; Whittaker, Maxine; Hsiang, Michelle S

    2016-09-13

    As malaria transmission declines, it becomes more geographically focused and more likely due to asymptomatic and non-falciparum infections. To inform malaria elimination planning in the context of this changing epidemiology, local assessments on the risk factors for malaria infection are necessary, yet challenging due to the low number of malaria cases. A population-based, cross-sectional study was performed using passive and active surveillance data collected in Aceh Besar District, Indonesia from 2014 to 2015. Malaria infection was defined as symptomatic polymerase chain reaction (PCR)-confirmed infection in index cases reported from health facilities, and asymptomatic or symptomatic PCR-confirmed infection identified in reactive case detection (RACD). Potential risk factors for any infection, species-specific infection, or secondary-case detection in RACD were assessed through questionnaires and evaluated for associations. Nineteen Plasmodium knowlesi, 12 Plasmodium vivax and six Plasmodium falciparum cases were identified passively, and 1495 community members screened in RACD, of which six secondary cases were detected (one P. knowlesi, three P. vivax, and two P. falciparum, with four being asymptomatic). Compared to non-infected subjects screened in RACD, cases identified through passive or active surveillance were more likely to be male (AOR 12.5, 95 % CI 3.0-52.1), adult (AOR 14.0, 95 % CI 2.2-89.6 for age 16-45 years compared to <15 years), have visited the forest in the previous month for any reason (AOR 5.6, 95 % CI 1.3-24.2), and have a workplace near or in the forest and requiring overnight stays (AOR 7.9, 95 % CI 1.6-39.7 compared to workplace not near or in the forest). Comparing subjects with infections of different species, differences were observed in sub-district of residence and other demographic and behavioural factors. Among subjects screened in RACD, cases compared to non-cases were more likely to be febrile and reside within 100 m of

  13. Functional genomic analyses of Enterobacter, Anopheles and Plasmodium reciprocal interactions that impact vector competence.

    PubMed

    Dennison, Nathan J; Saraiva, Raúl G; Cirimotich, Chris M; Mlambo, Godfree; Mongodin, Emmanuel F; Dimopoulos, George

    2016-08-22

    Malaria exerts a tremendous socioeconomic impact worldwide despite current control efforts, and novel disease transmission-blocking strategies are urgently needed. The Enterobacter bacterium Esp_Z, which is naturally harboured in the mosquito midgut, can inhibit the development of Plasmodium parasites prior to their invasion of the midgut epithelium through a mechanism that involves oxidative stress. Here, a multifaceted approach is used to study the tripartite interactions between the mosquito, Esp_Z and Plasmodium, towards addressing the feasibility of using sugar-baited exposure of mosquitoes to the Esp_Z bacterium for interruption of malaria transmission. The ability of Esp_Z to colonize Anopheles gambiae midguts harbouring microbiota derived from wild mosquitoes was determined by qPCR. Upon introduction of Esp_Z via nectar feeding, the permissiveness of colonized mosquitoes to Plasmodium falciparum infection was determined, as well as the impact of Esp_Z on mosquito fitness parameters, such as longevity, number of eggs laid and number of larvae hatched. The genome of Esp_Z was sequenced, and transcriptome analyses were performed to identify bacterial genes that are important for colonization of the mosquito midgut, as well as for ROS-production. A gene expression analysis of members of the oxidative defence pathway of Plasmodium berghei was also conducted to assess the parasite's oxidative defence response to Esp_Z exposure. Esp_Z persisted for up to 4 days in the An. gambiae midgut after introduction via nectar feeding, and was able to significantly inhibit Plasmodium sporogonic development. Introduction of this bacterium did not adversely affect mosquito fitness. Candidate genes involved in the selection of a better fit Esp_Z to the mosquito midgut environment and in its ability to condition oxidative status of its surroundings were identified, and parasite expression data indicated that Esp_Z is able to induce a partial and temporary shutdown of the

  14. Attacking Plasmodium vivax

    PubMed Central

    Baird, J. Kevin

    2016-01-01

    Discussions beginning in 2012 ultimately led to a landmark document from the World Health Organization (WHO) titled, Control and Elimination of Plasmodium vivax: A Technical Brief, published in July 2015. That body of work represents multiple expert consultations coordinated by the WHO Global Malaria Program, along with technical consensus gathering from national malaria control programs via the WHO regional offices around the globe. That document thus represents thoroughly vetted state-of-the-art recommendations for dealing specifically with P. vivax, the first assembly of such by the WHO. This supplement to the journal was commissioned by the WHO and compiles the very substantial body of evidence and analysis informing those recommendations. This introductory narrative to the supplement provides the historical and technological context of global strategy for combatting P. vivax and reducing the burdens of morbidity and mortality it imposes. PMID:27708186

  15. Naturally Acquired Antibodies Specific for Plasmodium falciparum Reticulocyte-Binding Protein Homologue 5 Inhibit Parasite Growth and Predict Protection From Malaria

    PubMed Central

    Tran, Tuan M.; Ongoiba, Aissata; Coursen, Jill; Crosnier, Cecile; Diouf, Ababacar; Huang, Chiung-Yu; Li, Shanping; Doumbo, Safiatou; Doumtabe, Didier; Kone, Younoussou; Bathily, Aboudramane; Dia, Seydou; Niangaly, Moussa; Dara, Charles; Sangala, Jules; Miller, Louis H.; Doumbo, Ogobara K.; Kayentao, Kassoum; Long, Carole A.; Miura, Kazutoyo; Wright, Gavin J.; Traore, Boubacar; Crompton, Peter D.

    2014-01-01

    Background. Plasmodium falciparum reticulocyte-binding protein homologue 5 (PfRH5) is a blood-stage parasite protein essential for host erythrocyte invasion. PfRH5-specific antibodies raised in animals inhibit parasite growth in vitro, but the relevance of naturally acquired PfRH5-specific antibodies in humans is unclear. Methods. We assessed pre–malaria season PfRH5-specific immunoglobulin G (IgG) levels in 357 Malian children and adults who were uninfected with Plasmodium. Subsequent P. falciparum infections were detected by polymerase chain reaction every 2 weeks and malaria episodes by weekly physical examination and self-referral for 7 months. The primary outcome was time between the first P. falciparum infection and the first febrile malaria episode. PfRH5-specific IgG was assayed for parasite growth-inhibitory activity. Results. The presence of PfRH5-specific IgG at enrollment was associated with a longer time between the first blood-stage infection and the first malaria episode (PfRH5-seropositive median: 71 days, PfRH5-seronegative median: 18 days; P = .001). This association remained significant after adjustment for age and other factors associated with malaria risk/exposure (hazard ratio, .62; P = .02). Concentrated PfRH5-specific IgG purified from Malians inhibited P. falciparum growth in vitro. Conclusions. Naturally acquired PfRH5-specific IgG inhibits parasite growth in vitro and predicts protection from malaria. These findings strongly support efforts to develop PfRH5 as an urgently needed blood-stage malaria vaccine. Clinical Trials Registration NCT01322581. PMID:24133188

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

    PubMed Central

    Guillotte, Micheline; Juillerat, Alexandre; Igonet, Sébastien; Hessel, Audrey; Petres, Stéphane; Crublet, Elodie; Le Scanf, Cécile; Lewit-Bentley, Anita; Bentley, Graham A.

    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

  17. Tafenoquine treatment of Plasmodium vivax malaria: suggestive evidence that CYP2D6 reduced metabolism is not associated with relapse in the Phase 2b DETECTIVE trial.

    PubMed

    St Jean, Pamela L; Xue, Zhengyu; Carter, Nick; Koh, Gavin C K W; Duparc, Stephan; Taylor, Maxine; Beaumont, Claire; Llanos-Cuentas, Alejandro; Rueangweerayut, Ronnatrai; Krudsood, Srivicha; Green, Justin A; Rubio, Justin P

    2016-02-18

    Tafenoquine (TQ) and primaquine (PQ) are 8-aminoquinolines (8-AQ) with anti-hypnozoite activity against vivax malaria. PQ is the only FDA-approved medicine for preventing relapsing Plasmodium vivax infection and TQ is currently in phase 3 clinical trials for the same indication. Recent studies have provided evidence that cytochrome P450 (CYP) metabolism via CYP2D6 plays a role in PQ efficacy against P. vivax and have suggested that this effect may extend to other 8-AQs, including TQ. Here, a retrospective pharmacogenetic (PGx) investigation was performed to assess the impact of CYP2D6 metabolism on TQ and PQ efficacy in the treatment of P. vivax in the DETECTIVE study (TAF112582), a recently completed, randomized, phase 2b dose-ranging clinical trial. The impact of CYP2D6 on TQ pharmacokinetics (PK) was also investigated in TAF112582 TQ-treated subjects and in vitro CYP metabolism of TQ was explored. A limitation of the current study is that TAF112582 was not designed to be well powered for PGx, thus our findings are based on TQ or PQ efficacy in CYP2D6 intermediate metabolizers (IM), as there were insufficient poor metabolizers (PM) to draw any conclusion on the impact of the PM phenotype on efficacy. The impact of genetically-predicted CYP2D6 reduced metabolism on relapse-free efficacy six months post-dosing of TQ or PQ, both administered in conjunction with chloroquine (CQ), was assessed using exact statistical methods in 198 P. vivax-infected study participants comparing IM to extensive metabolizers (EM). The influence of CYP2D6 metabolizer phenotypes on TQ PK was assessed comparing median TQ area under the curve (AUC). In vitro metabolism of TQ was investigated using recombinant, over-expressed human CYP enzymes and human hepatocytes. Metabolite identification experiments were performed using liquid chromatography-mass spectrometry. Reduction of CYP2D6 activity was not associated with an increase in relapse-rate in TQ-treated subjects (p = 0.57). In contrast

  18. In silico and biological survey of transcription-associated proteins implicated in the transcriptional machinery during the erythrocytic development of Plasmodium falciparum

    PubMed Central

    2010-01-01

    Background Malaria is the most important parasitic disease in the world with approximately two million people dying every year, mostly due to Plasmodium falciparum infection. During its complex life cycle in the Anopheles vector and human host, the parasite requires the coordinated and modulated expression of diverse sets of genes involved in epigenetic, transcriptional and post-transcriptional regulation. However, despite the availability of the complete sequence of the Plasmodium falciparum genome, we are still quite ignorant about Plasmodium mechanisms of transcriptional gene regulation. This is due to the poor prediction of nuclear proteins, cognate DNA motifs and structures involved in transcription. Results A comprehensive directory of proteins reported to be potentially involved in Plasmodium transcriptional machinery was built from all in silico reports and databanks. The transcription-associated proteins were clustered in three main sets of factors: general transcription factors, chromatin-related proteins (structuring, remodelling and histone modifying enzymes), and specific transcription factors. Only a few of these factors have been molecularly analysed. Furthermore, from transcriptome and proteome data we modelled expression patterns of transcripts and corresponding proteins during the intra-erythrocytic cycle. Finally, an interactome of these proteins based either on in silico or on 2-yeast-hybrid experimental approaches is discussed. Conclusion This is the first attempt to build a comprehensive directory of potential transcription-associated proteins in Plasmodium. In addition, all complete transcriptome, proteome and interactome raw data were re-analysed, compared and discussed for a better comprehension of the complex biological processes of Plasmodium falciparum transcriptional regulation during the erythrocytic development. PMID:20078850

  19. Risk of drug resistance in Plasmodium falciparum malaria therapy-a systematic review and meta-analysis.

    PubMed

    Zhou, Li-Juan; Xia, Jing; Wei, Hai-Xia; Liu, Xiao-Jun; Peng, Hong-Juan

    2017-02-01

    Plasmodium falciparum is responsible for the vast majority of the morbidity and mortality associated with malaria infection globally. Although a number of studies have reported the emergence of drug resistance in different therapies for P. falciparum infection, the degree of the drug resistance in different antimalarials is still unclear. This research investigated the risk of drug resistance in the therapies with different medications based on meta-analyses. Relevant original randomized control trials (RCTs) were searched in all available electronic databases. Pooled relative risks (RRs) with 95% confidence intervals (95% CIs) were used to evaluate the risk of drug resistance resulting from different treatments. Seventy-eight studies were included in the meta-analysis to compare drug resistance in the treatment of P. falciparum infections and yielded the following results: chloroquine (CQ) > sulfadoxine-pyrimethamine (SP) (RR = 3.67, p < 0.001 ), mefloquine (MQ) < SP (RR = 0.26, p < 0.001), artesunate + sulfadoxine-pyrimethamine (AS + SP) > artemether + lumefantrine (AL) (RR = 2.94, p < 0.001), dihydroartemisinin + piperaquine (DHA + PQ) < AL (RR = 0.7, p < 0.05), and non-artemisinin-based combination therapies (NACTs) > artemisinin-based combination therapies (ACTs) (RR = 1.93, p < 0.001); no significant difference was found in amodiaquine (AQ) vs. SP, AS + AQ vs. AS + SP, AS + AQ vs. AL, or AS + MQ vs. AL. These results presented a global view for the current status of antimalarial drug resistance and provided a guidance for choice of antimalarials for efficient treatment and prolonging the life span of the current effective antimalarial drugs.

  20. Pre-amplification methods for tracking low-grade Plasmodium falciparum populations during scaled-up interventions in Southern Zambia

    PubMed Central

    2014-01-01

    Background Malaria is receding in many endemic countries with intervention scale -up against the disease. However, this resilient scourge may persist in low-grade submicroscopic infections among semi-immune members of the population, and be poised for possible resurgence, creating challenges for detection and assessment of intervention impact. Parasite genotyping methods, such as the molecular barcode, can identify specific malaria parasite types being transmitted and allow tracking and evaluation of parasite population structure changes as interventions are applied. This current study demonstrates application of pre-amplification methods for successful detection and genotyping of residual Plasmodium falciparum infections during a dramatic malarial decline. Methods The study was a prospective cross-sectional design and based on a 2,000 sq km vicinity of Macha Mission Hospital in southern Zambia. Willing and predominantly asymptomatic residents of all ages were screened for malaria by microscopy during the 2005 and 2008 transmission seasons, with simultaneous collection of dried blood spots (DBS) on filter paper, and extraction of Plasmodium falciparum DNA was performed. Plasmodium falciparum infections were genotyped using a 24 SNP-based molecular barcode assay using real-time PCR. Submicroscopic parasitaemia samples were subjected to pre-amplification using TaqMan PreAmp Master Mix following the manufacturer’s instructions before SNP barcode analysis. Results There was a dramatic decline of malaria between 2005 and 2008, and the geometric mean parasite density (95% CI) fell from 704/μL (390–1,271) in 2005 to 39/μL (23–68) in 2008, culminating in a large proportion of submicroscopic infections of which 90% failed to yield ample DNA for standard molecular characterization among 2008 samples. Pre-amplification enabled successful detection and genotyping of 74% of these low-grade reservoir infections, overall, compared to 54% that were detectable before pre

  1. Pre-amplification methods for tracking low-grade Plasmodium falciparum populations during scaled-up interventions in Southern Zambia.

    PubMed

    Mharakurwa, Sungano; Daniels, Rachel; Scott, Alan; Wirth, Dyann F; Thuma, Philip; Volkman, Sarah K

    2014-03-12

    Malaria is receding in many endemic countries with intervention scale -up against the disease. However, this resilient scourge may persist in low-grade submicroscopic infections among semi-immune members of the population, and be poised for possible resurgence, creating challenges for detection and assessment of intervention impact. Parasite genotyping methods, such as the molecular barcode, can identify specific malaria parasite types being transmitted and allow tracking and evaluation of parasite population structure changes as interventions are applied. This current study demonstrates application of pre-amplification methods for successful detection and genotyping of residual Plasmodium falciparum infections during a dramatic malarial decline. The study was a prospective cross-sectional design and based on a 2,000 sq km vicinity of Macha Mission Hospital in southern Zambia. Willing and predominantly asymptomatic residents of all ages were screened for malaria by microscopy during the 2005 and 2008 transmission seasons, with simultaneous collection of dried blood spots (DBS) on filter paper, and extraction of Plasmodium falciparum DNA was performed. Plasmodium falciparum infections were genotyped using a 24 SNP-based molecular barcode assay using real-time PCR. Submicroscopic parasitaemia samples were subjected to pre-amplification using TaqMan PreAmp Master Mix following the manufacturer's instructions before SNP barcode analysis. There was a dramatic decline of malaria between 2005 and 2008, and the geometric mean parasite density (95% CI) fell from 704/μL (390-1,271) in 2005 to 39/μL (23-68) in 2008, culminating in a large proportion of submicroscopic infections of which 90% failed to yield ample DNA for standard molecular characterization among 2008 samples. Pre-amplification enabled successful detection and genotyping of 74% of these low-grade reservoir infections, overall, compared to 54% that were detectable before pre-amplification (p <0.0005, n = 84

  2. The prognostic value of schizontaemia in imported Plasmodium falciparum malaria

    PubMed Central

    2012-01-01

    Background In Plasmodium falciparum infection, peripheral parasite counts do not always correlate well with the sequestered parasite burden. As erythrocytes parasitized with mature trophozoites and schizonts have a high tendency to adhere to the microvascular endothelium, they are often absent in peripheral blood samples. The appearance of schizonts in peripheral blood smears is thought to be a marker of high sequestered parasite burden and severe disease. In the present study, the value of schizontaemia as an early marker for severe disease in non-immune individuals with imported malaria was evaluated. Methods All patients in the Rotterdam Malaria Cohort diagnosed with P. falciparum malaria between 1 January 1999 and 1 January 2012 were included. Thick and thin blood films were examined for the presence of schizontaemia. The occurrence of WHO defined severe malaria was the primary endpoint. The diagnostic performance of schizontaemia was compared with previously evaluated biomarkers C-reactive protein and lactate. Results Schizonts were present on admission in 49 of 401 (12.2%) patients. Patients with schizontaemia were more likely to present with severe malaria, a more complicated course and had longer duration of admission in hospital. Schizontaemia had a specificity of 0.95, a sensitivity of 0.53, a negative predictive value of 0.92 and a positive predictive value of 0.67 for severe malaria. The presence of schizonts was an independent predictor for severe malaria. Conclusion Absence of schizonts was found to be a specific marker for exclusion of severe malaria. Presence of schizonts on admission was associated with a high positive predictive value for severe malaria. This may be of help to identify patients who are at risk of a more severe course than would be expected when considering peripheral parasitaemia alone. PMID:22929647

  3. Sero-epidemiological evaluation of Plasmodium falciparum malaria in Senegal.

    PubMed

    Sylla, Khadime; Tine, Roger Clément Kouly; Ndiaye, Magatte; Sow, Doudou; Sarr, Aïssatou; Mbuyi, Marie Louise Tshibola; Diouf, Ibrahima; Lô, Amy Colé; Abiola, Annie; Seck, Mame Cheikh; Ndiaye, Mouhamadou; Badiane, Aïda Sadikh; N'Diaye, Jean Louis A; Ndiaye, Daouda; Faye, Oumar; Dieng, Thérèse; Dieng, Yémou; Ndir, Oumar; Gaye, Oumar; Faye, Babacar

    2015-07-16

    In Senegal, a significant decrease of malaria transmission intensity has been noted the last years. Parasitaemia has become lower and, therefore, more difficult to detect by microscopy. In the context of submicroscopic parasitaemia, it has become relevant to rely on relevant malaria surveillance tools to better document malaria epidemiology in such settings. Serological markers have been proposed as an essential tool for malaria surveillance. This study aimed to evaluate the sero-epidemiological situation of Plasmodium falciparum malaria in two sentinel sites in Senegal. Cross-sectional surveys were carried out in Velingara (south Senegal) and Keur Soce (central Senegal) between September and October 2010. Children under 10 years old, living in these areas, were enrolled using two-level, random sampling methods. P. falciparum infection was diagnosed using microscopy. P. falciparum antibodies against circumsporozoite protein (CSP), apical membrane protein (AMA1) and merozoite surface protein 1_42 (MSP1_42) were measured by ELISA method. A stepwise logistic regression analysis was done to assess factors associated with P. falciparum antibodies carriage. A total of 1,865 children under 10 years old were enrolled. The overall falciparum malaria prevalence was 4.99% with high prevalence in Velingara of 10.03% compared to Keur Soce of 0.3%. Symptomatic malaria cases (fever associated with parasitaemia) represented 17.37%. Seroprevalence of anti-AMA1, anti-MSP1_42 and anti-CSP antibody was 38.12, 41.55 and 40.38%, respectively. The seroprevalence was more important in Velingara and increased with age, active malaria infection and area of residence. The use of serological markers can contribute to improved malaria surveillance in areas with declining malaria transmission. This study provided useful baseline information about the sero-epidemiological situation of malaria in Senegal and can contribute to the identification of malaria hot spots in order to concentrate

  4. Chloroquine-resistant Plasmodium vivax malaria in Debre Zeit, Ethiopia

    PubMed Central

    Teka, Hiwot; Petros, Beyene; Yamuah, Lawrence; Tesfaye, Gezahegn; Elhassan, Ibrahim; Muchohi, Simon; Kokwaro, Gilbert; Aseffa, Abraham; Engers, Howard

    2008-01-01

    Background Plasmodium vivax accounts for about 40% of all malaria infection in Ethiopia. Chloroquine (CQ) is the first line treatment for confirmed P. vivax malaria in the country. The first report of CQ treatment failure in P. vivax was from Debre Zeit, which suggested the presence of chloroquine resistance. Methods An in vivo drug efficacy study was conducted in Debre Zeit from June to August 2006. Eighty-seven patients with microscopically confirmed P. vivax malaria, aged between 8 months and 52 years, were recruited and treated under supervision with CQ (25 mg/kg over three days). Clinical and parasitological parameters were assessed during the 28 day follow-up period. CQ and desethylchloroquine (DCQ) blood and serum concentrations were determined with high performance liquid chromatography (HPLC) in patients who showed recurrent parasitaemia. Results Of the 87 patients recruited in the study, one was lost to follow-up and three were excluded due to P. falciparum infection during follow-up. A total of 83 (95%) of the study participants completed the follow-up. On enrolment, 39.8% had documented fever and 60.2% had a history of fever. The geometric mean parasite density of the patients was 7045 parasites/μl. Among these, four patients had recurrent parasitaemia on Day 28. The blood CQ plus DCQ concentrations of these four patients were all above the minimal effective concentration (> 100 ng/ml). Conclusion Chloroquine-resistant P. vivax parasites are emerging in Debre Zeit, Ethiopia. A multi-centre national survey is needed to better understand the extent of P. vivax resistance to CQ in Ethiopia. PMID:18959774

  5. Plasmodium falciparum and Plasmodium vivax Infections in the Peruvian Amazon: Propagation of Complex, Multiple Allele-Type Infections without Super-Infection

    PubMed Central

    Sutton, Patrick L.; Neyra, Victor; Hernandez, Jean N.; Branch, OraLee H.

    2013-01-01

    Outcrossing potential between Plasmodium parasites is defined by the population-level diversity (PLD) and complexity of infection (COI). There have been few studies of PLD and COI in low transmission regions. Since the 1995–1998 Peruvian Amazon epidemic, there has been sustained transmission with < 0.5 P. falciparum and < 1.6 P. vivax infections/person/year. Using weekly active case detection, we described PLD by heterozygosity (He) and COI using P. falciparum Pfmsp1-B2 and P. vivax Pvmsp3α. Not being homologous genes, we limited comparisons to within species. P. falciparum (N = 293) had low (He = 0.581) and P. vivax (N = 186) had high (He= 0.845) PLD. A total of 9.5% P. falciparum infections and 26.3% P. vivax infections had COI > 1. Certain allele types were in more mixed infections than expected by chance. The few appearances of new alleles could be explained by stochastic polymerase chain reaction detection or synchronization/sequestration. The results suggest propagation of mixed infections by multiple inocula, not super-infection, implying decade-long opportunity for outcrossing in these mixed infections. PMID:19996422

  6. Identification of Caucasian CD4 T cell epitopes on the circumsporozoite protein of Plasmodium vivax. T cell memory.

    PubMed

    Bilsborough, J; Carlisle, M; Good, M F

    1993-07-15

    We have identified a population of Caucasians with a defined past history of infection with Plasmodium vivax malaria. Using purified synthetic peptides overlapping the sequence of the circumsporozoite protein, we determined the percentage of individuals whose T cells proliferated or secreted IFN-gamma in response to peptide stimulation, for both this population and a population of nonmalaria-exposed control individuals. A number of peptides were recognized by both groups, but 11 peptides were uniquely recognized by the exposed population, and thus represented malaria-specific T cell epitopes. CD4 T cells were found to be responsible for the proliferative response. Humans last exposed to vivax sporozoites as long ago as 49 yr responded as well or better to these malaria-specific epitopes as individuals exposed within the previous month. Since such malaria-induced memory response may not be a feature of Plasmodium falciparum infections, and since P. falciparum does not have a persisting hypnozoite stage, our data argue that the persistence of T cell memory to vivax epitopes may result from antigenic persistence in the liver.

  7. 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

  8. 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.

  9. Directly-observed therapy (DOT) for the radical 14-day primaquine treatment of Plasmodium vivax malaria on the Thai-Myanmar border

    PubMed Central

    2010-01-01

    Background Plasmodium vivax has a dormant hepatic stage, called the hypnozoite, which can cause relapse months after the initial attack. For 50 years, primaquine has been used as a hypnozoitocide to radically cure P. vivax infection, but major concerns remain regarding the side-effects of the drug and adherence to the 14-day regimen. This study examined the effectiveness of using the directly-observed therapy (DOT) method for the radical treatment of P. vivax malaria infection, to prevent reappearance of the parasite within the 90-day follow-up period. Other potential risk factors for the reappearance of P. vivax were also explored. Methods A randomized trial was conducted from May 2007 to January 2009 in a low malaria transmission area along the Thai-Myanmar border. Patients aged ≥ 3 years diagnosed with P. vivax by microscopy, were recruited. All patients were treated with the national standard regimen of chloroquine for three days followed by primaquine for 14 days. Patients were randomized to receive DOT or self-administered therapy (SAT). All patients were followed for three months to check for any reappearance of P. vivax. Results Of the 216 patients enrolled, 109 were randomized to DOT and 107 to SAT. All patients recovered without serious adverse effects. The vivax reappearance rate was significantly lower in the DOT group than the SAT group (3.4/10,000 person-days vs. 13.5/10,000 person-days, p = 0.021). Factors related to the reappearance of vivax malaria included inadequate total primaquine dosage received (< 2.75 mg/kg), duration of fever ≤ 2 days before initiation of treatment, parasite count on admission ≥ 10,000/µl, multiple P. vivax-genotype infection, and presence of P. falciparum infection during the follow-up period. Conclusions Adherence to the 14-day primaquine regimen is important for the radical cure of P. vivax malaria infection. Implementation of DOT reduces the reappearance rate of the parasite, and may subsequently decrease P

  10. Is Fc gamma receptor IIA (FcγRIIA) polymorphism associated with clinical malaria and Plasmodium falciparum specific antibody levels in children from Burkina Faso?

    PubMed

    Cherif, Mariama K; Sanou, Guillaume S; Bougouma, Edith C; Diarra, Amidou; Ouédraogo, Alphonse; Dolo, Amagana; Troye-Blomberg, Marita; Cavanagh, David R; Theisen, Michael; Modiano, David; Sirima, Sodiomon B; Nebié, Issa

    2015-02-01

    In the present study, the influences of FcγRIIA polymorphism on susceptibility to malaria and antibody responses to Plasmodium falciparum antigens were analyzed in children. We recruited 96 healthy children between 3 and 10 years at the beginning of the high transmission season and we followed up for 5 months through the high transmission season to assess the parasitological, immunological and genetic endpoints in relation to clinical malaria status. There was a similar distribution of homozygous and heterozygous individuals carrying the FcγRIIA-131R/R and FcγRIIA-131R/H allele, whereas the number of FcγRIIA-131H/H homozygous individuals was lower. P. falciparum infection frequency was not associated with the FcγRIIa-131R/H polymorphism. Only IgG antibody responses to GLURP R0 showed a significant association between antibody levels and FcγRIIA polymorphism (p=0.02). IgG levels to MSP2a were significantly higher in children who did not experience any clinical malaria episode compared to those who experienced at least one malaria episode (p=0.019). Cytophilic and non-cytophylic IgG subclass levels were higher in children without malaria than those who experienced at least one malaria episode. This difference was statistically significant for IgG1 to MSP3 (p=0.003) and to MSP2a (p=0.006); IgG3 to MSP2a (p=0.007) and to GLURP R0 (p=0.044); IgG2 to MSP2b (p=0.007) and IgG4 to MSP3 (p=0.051) and to MSP2a (p=0.049). In this study, homozygous carriers of the FcγRIIA-131R/R allele had higher malaria-specific antibody levels compare to the heterozygous carriers FcγRIIA-131R/H alleles and to homozygous carriers of FcγRIIA-131H/H alleles. The pre-existing antibodies responses were related to a reduced subsequent risk of clinical malaria.

  11. Reduction of multiplicity of infections but no change in msp2 genetic diversity in Plasmodium falciparum isolates from Congolese children after introduction of artemisinin-combination therapy.

    PubMed

    Ibara-Okabande, Rod; Koukouikila-Koussounda, Felix; Ndounga, Mathieu; Vouvoungui, Jeannhey; Malonga, Vladimir; Casimiro, Prisca Nadine; Ibara, Jean Rosaire; Sidibe, Anissa; Ntoumi, Francine

    2012-12-07

    In this first study conducted after the introduction of artemisinin-combination therapy (ACT), the major objective was to evaluate Plasmodium falciparum genetic diversity and multiplicity of infection in isolates from Congolese children between one and nine years of age enrolled and followed up for one year. The secondary objective was to characterize the msp2 profiles of P. falciparum isolates collected from successive malaria episodes in ten children who had four or more clinical episodes during the follow up. Three-hundred and thirteen children residing in southern part of Brazzaville participated in this study. Blood samples were obtained from all children at enrollment and checked for P. falciparum infection. Based on the one year follow-up data, two clinical groups were considered according to the number of malaria episodes presented over the follow up period: "protected"(children who did not experience any episode) and "unprotected" (those who experienced more that two episodes). Therefore, the msp2 genetic diversity of P. falciparum isolates collected at enrollment in the two groups was characterized by allele-specific nested PCR and compared. The msp2 profiles of P. falciparum isolates collected from successive malaria episodes was also characterized by allele-specific nested PCR. Forty-three percent of FC27 and fifty-seven percent of 3D7 in protected vs fifty-six percent of FC27 and forty-four percent of 3D7 in isolates from unprotected children were detected. Seven and two alleles belonging to the FC27, and six and three alleles belonging to 3D7 families were distinguished in isolates from protected and unprotected children respectively. The mean multiplicity of infection (MOI) values at inclusion for the msp2 locus was 1.29 and 1.43 for protected and unprotected children respectively. 43 isolates were obtained from the ten children who had four or more clinical episodes during the follow up. A total of 63 alleles or fragments corresponding to 57% (36

  12. Reduction of multiplicity of infections but no change in msp2 genetic diversity in Plasmodium falciparum isolates from Congolese children after introduction of artemisinin-combination therapy

    PubMed Central

    2012-01-01

    Background In this first study conducted after the introduction of artemisinin-combination therapy (ACT), the major objective was to evaluate Plasmodium falciparum genetic diversity and multiplicity of infection in isolates from Congolese children between one and nine years of age enrolled and followed up for one year. The secondary objective was to characterize the msp2 profiles of P. falciparum isolates collected from successive malaria episodes in ten children who had four or more clinical episodes during the follow up. Methods Three-hundred and thirteen children residing in southern part of Brazzaville participated in this study. Blood samples were obtained from all children at enrollment and checked for P. falciparum infection. Based on the one year follow-up data, two clinical groups were considered according to the number of malaria episodes presented over the follow up period: “protected”(children who did not experience any episode) and “unprotected” (those who experienced more that two episodes). Therefore, the msp2 genetic diversity of P. falciparum isolates collected at enrollment in the two groups was characterized by allele-specific nested PCR and compared. The msp2 profiles of P. falciparum isolates collected from successive malaria episodes was also characterized by allele-specific nested PCR. Results Forty-three percent of FC27 and fifty-seven percent of 3D7 in protected vs fifty-six percent of FC27 and forty-four percent of 3D7 in isolates from unprotected children were detected. Seven and two alleles belonging to the FC27, and six and three alleles belonging to 3D7 families were distinguished in isolates from protected and unprotected children respectively. The mean multiplicity of infection (MOI) values at inclusion for the msp2 locus was 1.29 and 1.43 for protected and unprotected children respectively. 43 isolates were obtained from the ten children who had four or more clinical episodes during the follow up. A total of 63 alleles or

  13. 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

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

    PubMed

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

    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.

  15. Manipulating the Plasmodium genome.

    PubMed

    Carvalho, Teresa Gil; Ménard, Robert

    2005-01-01

    Genome manipulation, the primary tool for assigning function to sequence, will be essential for understanding Plasmodium biology and malaria pathogenesis in molecular terms. The first success in transfecting Plasmodium was reported almost ten years ago. Gene-targeting studies have since flourished, as Plasmodium is haploid and integrates DNA only by homologous recombination. These studies have shed new light on the function of many proteins, including vaccine candidates and drug resistance factors. However, many essential proteins, including those involved in parasite invasion of erythrocytes, cannot be characterized in the absence of conditional mutagenesis. Proteins also cannot be identified on a functional basis as random DNA integration has not been achieved. We overview here the ways in which the Plasmodium genome can be manipulated. We also point to the tools that should be established if our goal is to address parasite infectivity in a systematic way and to conduct refined structure-function analysis of selected products.

  16. Adherence of infected erythrocytes to venular endothelium selects for antigenic variants of Plasmodium falciparum.

    PubMed

    Biggs, B A; Anders, R F; Dillon, H E; Davern, K M; Martin, M; Petersen, C; Brown, G V

    1992-09-15

    Erythrocytes (E) infected with asexual forms of malaria parasites exhibit surface antigenic variation. In Plasmodium falciparum infections, the variant Ag is the P. falciparum E membrane protein 1 (PfEMP1). This molecule may also mediate the adherence of infected E to host venular endothelium. We show here that parasite lines selected for increased adherence to endothelial cells have undergone antigenic variation. Three adherent lines selected from the same P. falciparum clone reacted with the same agglutinating antiserum that failed to agglutinate the parental clone. Immunoprecipitation experiments with the agglutinating anti-serum demonstrated that the selected lines expressed cross-reactive forms of PfEMP1 that were of higher m.w. and antigenically distinct from PfEMP1 of the parental clone. When one of the adherent lines was cloned in the absence of selection, a range of variant antigenic types emerged with differing cytoadherence phenotypes. These findings show that selection for cytoadherence in vitro favors the emergence of antigenic variants of P. falciparum and suggest that the requirement for cytoadherence in vivo may restrict the range of antigenic variants of P. falciparum in natural infections.

  17. Evaluation of a rapid and inexpensive dipstick assay for the diagnosis of Plasmodium falciparum malaria.

    PubMed Central

    Mills, C. D.; Burgess, D. C.; Taylor, H. J.; Kain, K. C.

    1999-01-01

    Rapid, accurate and affordable methods are needed for the diagnosis of malaria. Reported here is an evaluation of a new immunochromatographic strip, the PATH Falciparum Malaria IC Strip, which is impregnated with an immobilized IgM monoclonal antibody that binds to the HRP-II antigen of Plasmodium falciparum. In contrast to other commercially available kits marketed for the rapid diagnosis of falciparum malaria, this kit should be affordable in the malaria-endemic world. Using microscopy and polymerase chain reaction (PCR)-based methods as reference standards, we compared two versions of the PATH test for the detection of P. falciparum infection in 200 febrile travellers. As determined by PCR and microscopy, 148 travellers had malaria, 50 of whom (33.8%) were infected with P. falciparum. Compared with PCR, the two versions of the PATH test had initial sensitivities of 90% and 88% and specificities of 97% and 96%, respectively, for the detection of falciparum malaria. When discrepant samples were retested blindly with a modified procedure (increased sample volume and longer washing step) the sensitivity and specificity of both kits improved to 96% and 99%, respectively. The two remaining false negatives occurred in samples with < 100 parasites per microliter of blood. The accuracy, simplicity and predicted low cost may make this test a useful diagnostic tool in malaria-endemic areas. PMID:10444878

  18. Plasmodium falciparum Mating Patterns and Mosquito Infectivity of Natural Isolates of Gametocytes

    PubMed Central

    Morlais, Isabelle; Nsango, Sandrine E.; Toussile, Wilson; Abate, Luc; Annan, Zeinab; Tchioffo, Majoline T.; Cohuet, Anna; Awono-Ambene, Parfait H.; Fontenille, Didier; Rousset, François; Berry, Antoine

    2015-01-01

    Plasmodium falciparum infections in malaria endemic areas often harbor multiple clones of parasites. However, the transmission success of the different genotypes within the mosquito vector has remained elusive so far. The genetic diversity of malaria parasites was measured by using microsatellite markers in gametocyte isolates from 125 asymptomatic carriers. For a subset of 49 carriers, the dynamics of co-infecting genotypes was followed until their development within salivary glands. Also, individual oocysts from midguts infected with blood from 9 donors were genotyped to assess mating patterns. Multiplicity of infection (MOI) was high both in gametocyte isolates and sporozoite populations, reaching up to 10 genotypes. Gametocyte isolates with multiple genotypes gave rise to lower infection prevalence and intensity. Fluctuations of genotype number occurred during the development within the mosquito and sub-patent genotypes, not detected in gametocyte isolates, were identified in the vector salivary glands. The inbreeding coefficient Fis was positively correlated to the oocyst loads, suggesting that P. falciparum parasites use different reproductive strategies according to the genotypes present in the gametocyte isolate. The number of parasite clones within an infection affects the transmission success and the mosquito has an important role in maintaining P. falciparum genetic diversity. Our results emphasize the crucial importance of discriminating between the different genotypes within an infection when studying the A. gambiae natural resistance to P. falciparum, and the need to monitor parasite diversity in areas where malaria control interventions are implemented. PMID:25875840

  19. A potent antimalarial benzoxaborole targets a Plasmodium falciparum cleavage and polyadenylation specificity factor homologue

    PubMed Central

    Sonoiki, Ebere; Ng, Caroline L.; Lee, Marcus C. S.; Guo, Denghui; Zhang, Yong-Kang; Zhou, Yasheen; Alley, M. R. K.; Ahyong, Vida; Sanz, Laura M.; Lafuente-Monasterio, Maria Jose; Dong, Chen; Schupp, Patrick G.; Gut, Jiri; Legac, Jenny; Cooper, Roland A.; Gamo, Francisco-Javier; DeRisi, Joseph; Freund, Yvonne R.; Fidock, David A.; Rosenthal, Philip J.

    2017-01-01

    Benzoxaboroles are effective against bacterial, fungal and protozoan pathogens. We report potent activity of the benzoxaborole AN3661 against Plasmodium falciparum laboratory-adapted strains (mean IC50 32 nM), Ugandan field isolates (mean ex vivo IC50 64 nM), and murine P. berghei and P. falciparum infections (day 4 ED90 0.34 and 0.57 mg kg−1, respectively). Multiple P. falciparum lines selected in vitro for resistance to AN3661 harboured point mutations in pfcpsf3, which encodes a homologue of mammalian cleavage and polyadenylation specificity factor subunit 3 (CPSF-73 or CPSF3). CRISPR-Cas9-mediated introduction of pfcpsf3 mutations into parental lines recapitulated AN3661 resistance. PfCPSF3 homology models placed these mutations in the active site, where AN3661 is predicted to bind. Transcripts for three trophozoite-expressed genes were lost in AN3661-treated trophozoites, which was not observed in parasites selected or engineered for AN3661 resistance. Our results identify the pre-mRNA processing factor PfCPSF3 as a promising antimalarial drug target. PMID:28262680

  20. Response of sensitized and unsensitized human lymphocyte subpopulations to Plasmodium falciparum antigens.

    PubMed Central

    Wyler, D J; Herrod, H G; Weinbaum, F I

    1979-01-01

    Antigen preparations derived from Plasmodium falciparum-infected erythrocytes (but not from uninfected erythrocytes) can stimulate the in vitro proliferation of peripheral blood lymphocytes from malaria-sensitized as well as nonsensitized donors. The possibility that the nonspecific responses might be due to a parasite-derived B-cell mitogen has been previously suggested since polyclonal hypergammaglobulinemia is a frequent accompaniment of malaria infection. To test this hypothesis, we investigated the in vitro proliferative responses of purified T- and B-cell populations to malaria antigens. T but not B cells responded to the antigens. The addition of small numbers of T cells restored the ability of purified B cells to respond to lectin mitogens but not to malaria antigens. Falciparum malaria infection was associated with an increase in T-cell but not in B-cell proliferation in vivo, as assessed by the spontaneous tritiated thymidine incorporation of lymphocytes during a brief incubation in vitro. Our observations suggest that extracts of malaria parasites do not contain a B-cell mitogen but are antigenic as well as mitogenic for T cells. PMID:378840

  1. Plasmodium falciparum isolates from patients with uncomplicated malaria promote endothelial inflammation.

    PubMed

    Vásquez, Ana María; Blair, Silvia; García, Luis F; Segura, Cesar

    2017-02-01

    The ability of Plasmodium falciparum infected erythrocytes (Pf-IEs) to activate endothelial cells has been described; however, the interaction of the endothelium with Pf-IEs field isolates from patients has been less characterized. Previous reports have shown that isolates alter the endothelial permeability and apoptosis. In this study, the adhesion of 19 uncomplicated malaria isolates to Human Dermal Microvascular Endothelial Cells (HDMEC), and their effect on the expression of ICAM-1 and proinflammatory molecules (sICAM-1, IL-6, IL-8, and MCP-1) was evaluated. P. falciparum isolates adhered to resting and TNFα-activated HDEMC cells at different levels. All isolates increased the ICAM-1 expression on the membrane (mICAM-1) of HDMEC and increased the release of its soluble form (sICAM-1), as well the production of IL-6, IL-8 and MCP-1 by HDMEC with no signs of cell apoptosis. No correlation between parasite adhesion and production of cytokines was observed. In conclusion, isolates from uncomplicated malaria can induce a proinflammatory response in endothelial cells that may play a role during the initial inflammatory response to parasite infection; however, a continuous activation of the endothelium can contribute to pathogenesis.

  2. A potent antimalarial benzoxaborole targets a Plasmodium falciparum cleavage and polyadenylation specificity factor homologue.

    PubMed

    Sonoiki, Ebere; Ng, Caroline L; Lee, Marcus C S; Guo, Denghui; Zhang, Yong-Kang; Zhou, Yasheen; Alley, M R K; Ahyong, Vida; Sanz, Laura M; Lafuente-Monasterio, Maria Jose; Dong, Chen; Schupp, Patrick G; Gut, Jiri; Legac, Jenny; Cooper, Roland A; Gamo, Francisco-Javier; DeRisi, Joseph; Freund, Yvonne R; Fidock, David A; Rosenthal, Philip J

    2017-03-06

    Benzoxaboroles are effective against bacterial, fungal and protozoan pathogens. We report potent activity of the benzoxaborole AN3661 against Plasmodium falciparum laboratory-adapted strains (mean IC50 32 nM), Ugandan field isolates (mean ex vivo IC50 64 nM), and murine P. berghei and P. falciparum infections (day 4 ED90 0.34 and 0.57 mg kg(-1), respectively). Multiple P. falciparum lines selected in vitro for resistance to AN3661 harboured point mutations in pfcpsf3, which encodes a homologue of mammalian cleavage and polyadenylation specificity factor subunit 3 (CPSF-73 or CPSF3). CRISPR-Cas9-mediated introduction of pfcpsf3 mutations into parental lines recapitulated AN3661 resistance. PfCPSF3 homology models placed these mutations in the active site, where AN3661 is predicted to bind. Transcripts for three trophozoite-expressed genes were lost in AN3661-treated trophozoites, which was not observed in parasites selected or engineered for AN3661 resistance. Our results identify the pre-mRNA processing factor PfCPSF3 as a promising antimalarial drug target.

  3. 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

  4. The Spiroindolone KAE609 Does Not Induce Dormant Ring Stages in Plasmodium falciparum Parasites

    PubMed Central

    Van Breda, Karin; Rowcliffe, Kerryn; Diagana, Thierry T.; Edstein, Michael D.

    2016-01-01

    In vitro drug treatment with artemisinin derivatives, such as dihydroartemisinin (DHA), results in a temporary growth arrest (i.e., dormancy) at an early ring stage in Plasmodium falciparum. This response has been proposed to play a role in the recrudescence of P. falciparum infections following monotherapy with artesunate and may contribute to the development of artemisinin resistance in P. falciparum malaria. We demonstrate here that artemether does induce dormant rings, a finding which further supports the class effect of artemisinin derivatives in inducing the temporary growth arrest of P. falciparum parasites. In contrast and similarly to lumefantrine, the novel and fast-acting spiroindolone compound KAE609 does not induce growth arrest at the early ring stage of P. falciparum and prevents the recrudescence of DHA-arrested rings at a low concentration (50 nM). Our findings, together with previous clinical data showing that KAE609 is active against artemisinin-resistant K13 mutant parasites, suggest that KAE609 could be an effective partner drug with a broad range of antimalarials, including artemisinin derivatives, in the treatment of multidrug-resistant P. falciparum malaria. PMID:27297484

  5. 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

  6. Competition between Plasmodium falciparum strains in clinical infections during in vitro culture adaptation.

    PubMed

    Chen, Kexuan; Sun, Ling; Lin, Yingxue; Fan, Qi; Zhao, Zhenjun; Hao, Mingming; Feng, Guohua; Wu, Yanrui; Cui, Liwang; Yang, Zhaoqing

    2014-06-01

    We evaluated the dynamics of parasite populations during in vitro culture adaptation in 15 mixed Plasmodium falciparum infections, which were collected from a hypoendemic area near the China-Myanmar border. Allele types at the msp1 block 2 in the initial clinical samples and during subsequent culture were quantified weekly using a quantitative PCR method. All mixed infections carried two allele types based on the msp1 genotyping result. We also genotyped several polymorphic sites in the dhfr, dhps and mdr1 genes on day 0 and day 28, which showed that most of the common sites analyzed were monomorphic. Two of the three clinical samples mixed at dhps 581 remained stable while one changed to wild-type during the culture. During in vitro culture, we observed a gradual loss of parasite populations with 10 of the 15 mixed infections becoming monoclonal by day 28 based on the msp1 allele type. In most cases, the more abundant msp1 allele types in the clinical blood samples at the beginning of culture became the sole or predominant allele types on day 28. These results suggest that some parasites may have growth advantages and the loss of parasite populations during culture adaptation of mixed infections may lead to biased results when comparing the phenotypes such as drug sensitivity of the culture-adapted parasites.

  7. Global proteomic analysis of prenylated proteins in Plasmodium falciparum using an alkyne-modified isoprenoid analogue

    PubMed Central

    Suazo, Kiall F.; Schaber, Chad; Palsuledesai, Charuta C.; Odom John, Audrey R.; Distefano, Mark D.

    2016-01-01

    Severe malaria due to Plasmodium falciparum infection remains a serious threat to health worldwide and new therapeutic targets are highly desirable. Small molecule inhibitors of prenyl transferases, enzymes that catalyze the post-translational isoprenyl modifications of proteins, exhibit potent antimalarial activity. The antimalarial actions of prenyltransferase inhibitors indicate that protein prenylation is required for malaria parasite development. In this study, we used a chemical biology strategy to experimentally characterize the entire complement of prenylated proteins in the human malaria parasite. In contrast to the expansive mammalian and fungal prenylomes, we find that P. falciparum possesses a restricted set of prenylated proteins. The prenylome of P. falciparum is dominated by Rab GTPases, in addition to a small number of prenylated proteins that also appear to function primarily in membrane trafficking. Overall, we found robust experimental evidence for a total of only thirteen prenylated proteins in P. falciparum, with suggestive evidence for an additional two probable prenyltransferase substrates. Our work contributes to an increasingly complete picture of essential, post-translational hydrophobic modifications in blood-stage P. falciparum. PMID:27924931

  8. Global proteomic analysis of prenylated proteins in Plasmodium falciparum using an alkyne-modified isoprenoid analogue.

    PubMed

    Suazo, Kiall F; Schaber, Chad; Palsuledesai, Charuta C; Odom John, Audrey R; Distefano, Mark D

    2016-12-07

    Severe malaria due to Plasmodium falciparum infection remains a serious threat to health worldwide and new therapeutic targets are highly desirable. Small molecule inhibitors of prenyl transferases, enzymes that catalyze the post-translational isoprenyl modifications of proteins, exhibit potent antimalarial activity. The antimalarial actions of prenyltransferase inhibitors indicate that protein prenylation is required for malaria parasite development. In this study, we used a chemical biology strategy to experimentally characterize the entire complement of prenylated proteins in the human malaria parasite. In contrast to the expansive mammalian and fungal prenylomes, we find that P. falciparum possesses a restricted set of prenylated proteins. The prenylome of P. falciparum is dominated by Rab GTPases, in addition to a small number of prenylated proteins that also appear to function primarily in membrane trafficking. Overall, we found robust experimental evidence for a total of only thirteen prenylated proteins in P. falciparum, with suggestive evidence for an additional two probable prenyltransferase substrates. Our work contributes to an increasingly complete picture of essential, post-translational hydrophobic modifications in blood-stage P. falciparum.

  9. 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

  10. Reduced Activity of Mutant Calcium-Dependent Protein Kinase 1 Is Compensated in Plasmodium falciparum through the Action of Protein Kinase G

    PubMed Central

    Ojo, Kayode K.; Mu, Jianbing; Maly, Dustin J.; Van Voorhis, Wesley C.

    2016-01-01

    ABSTRACT We used a sensitization approach that involves replacement of the gatekeeper residue in a protein kinase with one with a different side chain. The activity of the enzyme with a bulky gatekeeper residue, such as methionine, cannot be inhibited using bumped kinase inhibitors (BKIs). Here, we have u