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Sample records for mixed-species plasmodium infections

  1. Development and Evaluation of a Rapid Diagnostic Test for Plasmodium falciparum, P. vivax, and Mixed-Species Malaria Antigens

    PubMed Central

    Lee, Gyu-Cheol; Jeon, Eun-Sung; Le, Dung Tien; Kim, Tong-Soo; Yoo, Jong-Ha; Kim, Hak Yong; Chong, Chom-Kyu

    2011-01-01

    Plasmodium falciparum and P. vivax malaria are endemic to many parts of the world and humans can be co-infected with both species. Because each Plasmodium species has different biological and clinical characteristics, accurate differentiation of the infecting species is essential for effective treatment. Therefore, we produced three monoclonal antibodies that recognize the lactate dehydrogenase of P. falciparum, P. vivax, or both to develop the first P. falciparum, P. vivax, and mixed-species infections malaria antigen detection kit. The detection limits of this kit were 150 and 250 parasites/μL for P. falciparum and P. vivax, respectively, and the kit was able to detect mixed-species infections. The sensitivity and specificity of this kit was assessed with 722 clinical specimens. Our results showed that its sensitivities for P. falciparum, P. vivax, and mixed-species infection were 96.5%, 95.3%, and 85.7%, respectively. In addition, its specificity was high (99.4%). PMID:22144432

  2. Effect of Transmission Setting and Mixed Species Infections on Clinical Measures of Malaria in Malawi

    PubMed Central

    Bruce, Marian C.; Macheso, Allan; Kelly-Hope, Louise A.; Nkhoma, Standwell; McConnachie, Alex; Molyneux, Malcolm E.

    2008-01-01

    Background In malaria endemic regions people are commonly infected with multiple species of malaria parasites but the clinical impact of these Plasmodium co-infections is unclear. Differences in transmission seasonality and transmission intensity between endemic regions have been suggested as important factors in determining the effect of multiple species co-infections. Principal Findings In order to investigate the impact of multiple-species infections on clinical measures of malaria we carried out a cross-sectional community survey in Malawi, in 2002. We collected clinical and parasitological data from 2918 participants aged >6 months, and applied a questionnaire to measure malaria morbidity. We examined the effect of transmission seasonality and intensity on fever, history of fever, haemoglobin concentration ([Hb]) and parasite density, by comparing three regions: perennial transmission (PT), high intensity seasonal transmission (HIST) and low intensity seasonal transmission (LIST). These regions were defined using multi-level modelling of PCR prevalence data and spatial and geo-climatic measures. The three Plasmodium species (P. falciparum, P. malariae and P. ovale) were randomly distributed amongst all children but not adults in the LIST and PT regions. Mean parasite density in children was lower in the HIST compared with the other two regions. Mixed species infections had lower mean parasite density compared with single species infections in the PT region. Fever rates were similar between transmission regions and were unaffected by mixed species infections. A history of fever was associated with single species infections but only in the HIST region. Reduced mean [Hb] and increased anaemia was associated with perennial transmission compared to seasonal transmission. Children with mixed species infections had higher [Hb] in the HIST region. Conclusions Our study suggests that the interaction of Plasmodium co-infecting species can have protective effects against

  3. Prevalence and distribution of human Plasmodium infection in Pakistan

    PubMed Central

    2013-01-01

    Background Both Plasmodium vivax and Plasmodium falciparum are prevalent in Pakistan, yet up-to-date data on the epidemiology of malaria in Pakistan are not available. This study was undertaken to determine the current prevalence and distribution of Plasmodium species across the country. Methods A malariometric population survey was conducted in 2011 using blood samples collected from 801 febrile patients of all ages in four provinces and the capital city of Islamabad. Microscopically confirmed Plasmodium-positive blood samples were reconfirmed by polymerase chain reaction (PCR). Confirmed parasite-positive samples were subjected to species-specific PCR capable of detecting four species of human malaria. Results Of the 707 PCR-positive samples, 128 (18%) were P. falciparum, 536 (76%) were P. vivax, and 43 (6%) were mixed P. falciparum and P. vivax. Ninety-four microscopy-positive samples were PCR-negative, and Plasmodium malariae and Plasmodium ovale were not detected. Prevalence of P. vivax ranged from 2.4% in Punjab Province to 10.8% in Sindh Province and prevalence of P. falciparum ranged from 0.1% in Islamabad to 3.8% in Balochistan. Conclusions Plasmodium infections in Pakistan are largely attributed to P. vivax but P. falciparum and mixed species infections are also prevalent. In addition, regional variation in the prevalence and species composition of malaria is high. PMID:23984968

  4. Facilitation through altered resource availability in a mixed-species rodent malaria infection.

    PubMed

    Ramiro, Ricardo S; Pollitt, Laura C; Mideo, Nicole; Reece, Sarah E

    2016-09-01

    A major challenge in disease ecology is to understand how co-infecting parasite species interact. We manipulate in vivo resources and immunity to explain interactions between two rodent malaria parasites, Plasmodium chabaudi and P. yoelii. These species have analogous resource-use strategies to the human parasites Plasmodium falciparum and P. vivax: P. chabaudi and P. falciparum infect red blood cells (RBC) of all ages (RBC generalist); P. yoelii and P. vivax preferentially infect young RBCs (RBC specialist). We find that: (1) recent infection with the RBC generalist facilitates the RBC specialist (P. yoelii density is enhanced ~10 fold). This occurs because the RBC generalist increases availability of the RBC specialist's preferred resource; (2) co-infections with the RBC generalist and RBC specialist are highly virulent; (3) and the presence of an RBC generalist in a host population can increase the prevalence of an RBC specialist. Thus, we show that resources shape how parasite species interact and have epidemiological consequences. PMID:27364562

  5. Intestinal establishment and reproduction of adult Trichinella spp. in single and mixed species infections in foxes (Vulpes vulpes).

    PubMed

    Webster, Pia; Kapel, Christian M O

    2005-06-30

    Intestinal establishment and reproduction of adult Trichinella spiralis, Trichinella nativa, Trichinella britovi and Trichinella pseudospiralis were examined as single species or mixed species infections in foxes. This is the first study of intestinal dynamics of Trichinella spp. in a carnivore model and the results suggest that the intestinal phase is relatively short as only very few worms were recovered 10 days post-inoculation (dpi). In mixed species infection with equal doses of T. nativa and T. spiralis, molecular typing demonstrated that 64% of the intestinal worms and 78% of the muscle larvae were T. nativa. Conversely, T. spiralis dominated in the mixed species infections with T. pseudospiralis, constituting 66% of the intestinal worms and 94% of the muscle larvae. Although, the individual recoveries of intestinal worms were only up to 5.6% on day 1, and up to 1.5% on day 4 post-infection, the muscle larvae establishment was comparable to other fox studies. Infectivity, measured as muscle larvae burden did not differ among the four species of Trichinella, which is in contrast to other models with mice, rats, pigs or herbivores. Although statistically significant differences in intestinal worm burdens were found for some days, no distinct species were recovered in consistently higher numbers than the others. PMID:15925724

  6. Immunoregulatory alterations in Plasmodium falciparum and Plasmodium vivax infections.

    PubMed

    Merino, F; Layrisse, Z; Godoy, G; Volcán, G

    1986-09-01

    Studies on the immune function of patients with acute Plasmodium vivax or P. falciparum infections were performed. All subjects were residing in recent malaria endemic areas of Venezuela. Lymphopenia, reduction of peripheral blood T-lymphocytes positive for monoclonal antibody OKT4 (T helper) a decrease of in vitro mitogenic proliferative response and natural killer cell activity were observed. Serum lymphocytotoxic antibodies reactive at 37 degrees C were detected in both groups of patients as well as serum autoantibodies. The possible role of lymphocytotoxic autoantibodies in the etiology of the T-lymphocyte depletion and acquired immunological perturbations in human malaria is discussed. PMID:2947313

  7. Engineered Anopheles Immunity to Plasmodium Infection

    PubMed Central

    Cirimotich, Chris; Souza-Neto, Jayme A.; McLean, Kyle J.; Dimopoulos, George

    2011-01-01

    A causative agent of human malaria, Plasmodium falciparum, is transmitted by Anopheles mosquitoes. The malaria parasite is under intensive attack from the mosquito's innate immune system during its sporogonic development. We have used genetic engineering to create immune-enhanced Anopheles stephensi mosquitoes through blood meal-inducible expression of a transgene encoding the IMD pathway-controlled NF-kB Rel2 transcription factor in the midgut and fat-body tissue. Transgenic mosquitoes showed greater resistance to Plasmodium and microbial infection as a result of timely concerted tissue-specific immune attacks involving multiple effectors. The relatively weak impact of this genetic modification on mosquito fitness under laboratory conditions encourages further investigation of this approach for malaria control. PMID:22216006

  8. Plasmodium knowlesi infection: a diagnostic challenge

    PubMed Central

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

    2013-01-01

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

  9. Transgenerational effect of infection in Plasmodium-infected mosquitoes.

    PubMed

    Pigeault, R; Vézilier, J; Nicot, A; Gandon, S; Rivero, A

    2015-03-01

    Transgenerational effects of infection have a huge potential to influence the prevalence and intensity of infections in vectors and, by extension, disease epidemiology. These transgenerational effects may increase the fitness of offspring through the transfer of protective immune factors. Alternatively, however, infected mothers may transfer the costs of infection to their offspring. Although transgenerational immune protection has been described in a dozen invertebrate species, we still lack a complete picture of the incidence and importance of transgenerational effects of infection in most invertebrate groups. The existence of transgenerational infection effects in mosquito vectors is of particular interest because of their potential for influencing parasite prevalence and intensity and, by extension, disease transmission. Here we present what we believe to be the first study on transgenerational infection effects in a mosquito vector infected with malaria parasites. The aim of this experiment was to quantify both the benefits and the costs of having an infected mother. We find no evidence of transgenerational protection in response to a Plasmodium infection. Having an infected mother does, however, entail considerable fecundity costs for the offspring: fecundity loss is three times higher in infected offspring issued from infected mothers than in infected offspring issued from uninfected mothers. We discuss the implications of our results and we call for more studies looking at transgenerational effects of infection in disease vectors. PMID:25762571

  10. A Case Report of Plasmodium Vivax, Plasmodium Falciparum and Dengue Co-Infection in a 6 Months Pregnancy

    PubMed Central

    Pande, A; Guharoy, D

    2013-01-01

    India being a tropical country, parasitic infections especially with Plasmodium species are very common in this region. The present case report is that of Plasmodium vivax, Plasmodium falciparum and dengue co-infection in a 6 months pregnant lady who was timely diagnosed and appropriately treated followed by a complete recovery along with feto-maternal well-being. PMID:24349838

  11. No Evidence for Ape Plasmodium Infections in Humans in Gabon

    PubMed Central

    Ollomo, Benjamin; Arnathau, Céline; Roche, Benjamin; Elguero, Eric; Moukodoum, Nancy Diamella; Okougha, Alain-Prince; Mve Ondo, Bertrand; Boundenga, Larson; Houzé, Sandrine; Galan, Maxime; Nkoghé, Dieudonné; Leroy, Eric M.; Durand, Patrick; Paupy, Christophe; Renaud, François; Prugnolle, Franck

    2015-01-01

    African great apes are naturally infected by a multitude of Plasmodium species most of them recently discovered, among which several are closely related to human malaria agents. However, it is still unknown whether these animals can serve as source of infections for humans living in their vicinity. To evaluate this possibility, we analysed the nature of Plasmodium infections from a bank of 4281 human blood samples collected in 210 villages of Gabon, Central Africa. Among them, 2255 were detected positive to Plasmodium using molecular methods (Plasmodium Cytochrome b amplification). A high throughput sequencing technology (454 GS-FLX Titanium technology, Roche) was then used to identify the Plasmodium species present within each positive sample. Overall, we identified with confidence only three species infecting humans in Gabon: P. falciparum, P. malariae and P. ovale. None of the species known to infect non-human primates in Central Africa was found. Our study shows that ape Plasmodium parasites of the subgenus Laverania do not constitute a frequent source of infection for humans. It also suggests that some strong host genetic barriers must exist to prevent the cross species transmission of ape Plasmodium in a context of ever increasing contacts between humans and wildlife. PMID:26039338

  12. The Dynamics of Natural Plasmodium falciparum Infections

    PubMed Central

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

    2012-01-01

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

  13. Functional analysis of erythrocyte determinants of Plasmodium infection

    PubMed Central

    Bei, Amy K.; Duraisingh, Manoj T.

    2012-01-01

    The Plasmodium falciparum parasite is an obligate intracellular pathogen whose invasion and remodeling of the human erythrocyte results in the clinical manifestations of malarial disease. The functional analysis of erythrocyte determinants of invasion and growth is a relatively unexplored frontier in malaria research, encompassing studies of natural variation of the erythrocyte, as well as genomic, biochemical and chemical biological and transgenic approaches. These studies have allowed the functional analysis of the erythrocyte in vitro, resulting in the discovery of critical erythrocyte determinants of Plasmodium infection. Here, we will focus on the varied approaches used for the study of the erythrocyte in Plasmodium infection, with a particular emphasis on erythrocyte invasion. PMID:22726752

  14. Colombian Anopheles triannulatus (Diptera: Culicidae) Naturally Infected with Plasmodium spp.

    PubMed Central

    Rosero, Doris A.; Naranjo-Diaz, Nelson; Alvarez, Natalí; Cienfuegos, Astrid V.; Luckhart, Shirley

    2013-01-01

    The role of Anopheles triannulatus as a local vector has not yet been defined for malaria-endemic regions of Colombia. Therefore, the aim of this work was to detect An. triannulatus naturally infected with Plasmodium spp., as an approximation to determining its importance as malaria vector in the country. A total of 510 An. triannulatus were collected in six malaria-endemic localities of NW and SE Colombia from January 2009 to March 2011. In the NW, two specimens were naturally infected; one with Plasmodium vivax VK247, collected biting on humans and the other with Plasmodium falciparum, collected resting on cattle. In the SE, two specimens were positive for P. falciparum. Although these results show An. triannulatus naturally infected with Plasmodium, further studies are recommended to demonstrate the epidemiological importance of this species in malaria-endemic regions of Colombia. PMID:27335865

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

    PubMed Central

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

    2014-01-01

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

  16. Host AMPK Is a Modulator of Plasmodium Liver Infection.

    PubMed

    Ruivo, Margarida T Grilo; Vera, Iset Medina; Sales-Dias, Joana; Meireles, Patrícia; Gural, Nil; Bhatia, Sangeeta N; Mota, Maria M; Mancio-Silva, Liliana

    2016-09-01

    Manipulation of the master regulator of energy homeostasis AMP-activated protein kinase (AMPK) activity is a strategy used by many intracellular pathogens for successful replication. Infection by most pathogens leads to an activation of host AMPK activity due to the energetic demands placed on the infected cell. Here, we demonstrate that the opposite is observed in cells infected with rodent malaria parasites. Indeed, AMPK activity upon the infection of hepatic cells is suppressed and dispensable for successful infection. By contrast, an overactive AMPK is deleterious to intracellular growth and replication of different Plasmodium spp., including the human malaria parasite, P. falciparum. The negative impact of host AMPK activity on infection was further confirmed in mice under conditions that activate its function. Overall, this work establishes the role of host AMPK signaling as a suppressive pathway of Plasmodium hepatic infection and as a potential target for host-based antimalarial interventions. PMID:27568570

  17. Mitochondrial Reactive Oxygen Species Modulate Mosquito Susceptibility to Plasmodium Infection

    PubMed Central

    Oliveira, Giselle A.; Andersen, John F.; Oliveira, Marcus F.; Oliveira, Pedro L.; Barillas-Mury, Carolina

    2012-01-01

    Background Mitochondria perform multiple roles in cell biology, acting as the site of aerobic energy-transducing pathways and as an important source of reactive oxygen species (ROS) that modulate redox metabolism. Methodology/Principal Findings We demonstrate that a novel member of the mitochondrial transporter protein family, Anopheles gambiae mitochondrial carrier 1 (AgMC1), is required to maintain mitochondrial membrane potential in mosquito midgut cells and modulates epithelial responses to Plasmodium infection. AgMC1 silencing reduces mitochondrial membrane potential, resulting in increased proton-leak and uncoupling of oxidative phosphorylation. These metabolic changes reduce midgut ROS generation and increase A. gambiae susceptibility to Plasmodium infection. Conclusion We provide direct experimental evidence indicating that ROS derived from mitochondria can modulate mosquito epithelial responses to Plasmodium infection. PMID:22815925

  18. Plasmodium malariae Infection Associated with a High Burden of Anemia: A Hospital-Based Surveillance Study

    PubMed Central

    Lampah, Daniel A.; Simpson, Julie A.; Kenangalem, Enny; Sugiarto, Paulus; Anstey, Nicholas M.; Poespoprodjo, Jeanne Rini; Price, Ric N.

    2015-01-01

    Background Plasmodium malariae is a slow-growing parasite with a wide geographic distribution. Although generally regarded as a benign cause of malaria, it has been associated with nephrotic syndrome, particularly in young children, and can persist in the host for years. Morbidity associated with P. malariae infection has received relatively little attention, and the risk of P. malariae-associated nephrotic syndrome is unknown. Methodology/Principal Findings We used data from a very large hospital-based surveillance system incorporating information on clinical diagnoses, blood cell parameters and treatment to describe the demographic distribution, morbidity and mortality associated with P. malariae infection in southern Papua, Indonesia. Between April 2004 and December 2013 there were 1,054,674 patient presentations to Mitra Masyarakat Hospital of which 196,380 (18.6%) were associated with malaria and 5,097 were with P. malariae infection (constituting 2.6% of all malaria cases). The proportion of malaria cases attributable to P. malariae increased with age from 0.9% for patients under one year old to 3.1% for patients older than 15 years. Overall, 8.5% of patients with P. malariae infection required admission to hospital and the median length of stay for these patients was 2.5 days (Interquartile Range: 2.0–4.0 days). Patients with P. malariae infection had a lower mean hemoglobin concentration (9.0g/dL) than patients with P. falciparum (9.5g/dL), P. vivax (9.6g/dL) and mixed species infections (9.3g/dL). There were four cases of nephrotic syndrome recorded in patients with P. malariae infection, three of which were in children younger than 5 years old, giving a risk in this age group of 0.47% (95% Confidence Interval; 0.10% to 1.4%). Overall, 2.4% (n = 16) of patients hospitalized with P. malariae infection subsequently died in hospital, similar to the proportions for the other endemic Plasmodium species (range: 0% for P. ovale to 1.6% for P. falciparum

  19. Prevalence and distribution of human Plasmodium infection in Federally Administrative Tribal Areas of Pakistan.

    PubMed

    Hussain, Irfan; Qureshi, Naveeda Akhtar; Afzal, Muhammad; Shaheen, Nargis; Ali, Abid; Ashraf, Asma

    2016-09-01

    About 3.6 million Pashtun and over 1.5 million immigrants from Afghanistan live in the federally administered tribal areas (FATA) on the border between Pakistan's Khyber Pakhtunkhwa Province and southern Afghanistan. Although malaria cases are common in FATA, no detailed studies have yet been performed to reveal the actual status of malaria in the local population and epidemiological data are insufficient to elucidate the actual incidence. A malariometric survey of 691 patients of all ages and genders in seven agencies (districts) in FATA was carried out in 2013 using whole blood samples. Microscopically confirmed positive species were subjected to nested-PCR for the reconfirmation and detection of four species of Plasmodium causing human malaria. Of the 626 PCR positive cases, 81.1% were P. vivax, 13.8% P. falciparum and 4.9% mixed species containing both P. vivax and P. falciparum. P. malariae and P. ovale and were not found in any analysis. Sixty-five microscopic positive samples were identified as negative by PCR. The incidence of P. vivax ranged from 10.4% in Orakzai Agency to 22.8% in North Waziristan Agency. The prevalence of P. falciparum ranged from 1.3% in Orakzai Agency to 4.7% in North Waziristan, and Khyber Agency had the highest prevalence of 1.7% of mixed species. In FATA, P. vivax and P. falciparum are the main causative agents of malaria, while mixed species infections are also prevalent with varying transmission intensities. In addition, Estimates of malaria incidence shows that variation in the incidence, frequency and species composition of malarial parasites is high. PMID:27447217

  20. Placental Histopathological Changes Associated with Plasmodium vivax Infection during Pregnancy

    PubMed Central

    Dombrowski, Jamille G.; Ippólito, Vanessa; Aitken, Elizabeth H.; Valle, Suiane N.; Álvarez, José M.; 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

  1. Physicochemical Aspects of the Plasmodium chabaudi-Infected Erythrocyte

    PubMed Central

    Hayakawa, Eri H.; Kobayashi, Seiki; Matsuoka, Hiroyuki

    2015-01-01

    Membrane electrochemical potential is a feature of the molecular profile of the cell membrane and the two-dimensional arrangement of its charge-bearing molecules. Plasmodium species, the causative agents of malaria, are intracellular parasites that remodel host erythrocytes by expressing their own proteins on erythrocyte membranes. Although various aspects of the modifications made to the host erythrocyte membrane have been extensively studied in some human Plasmodium species (such as Plasmodium falciparum), details of the structural and molecular biological modifications made to host erythrocytes by nonhuman Plasmodium parasites have not been studied. We employed zeta potential analysis of erythrocytes parasitized by P. chabaudi, a nonhuman Plasmodium parasite. From these measurements, we found that the surface potential shift was more negative for P. chabaudi-infected erythrocytes than for P. falciparum-infected erythrocytes. However, electron microscopic analysis of the surface of P. chabaudi-infected erythrocytes did not reveal any modifications as compared with nonparasitized erythrocytes. These results suggest that differences in the membrane modifications found herein represent unique attributes related to the pathogenesis profiles of the two different malaria parasite species in different host animals and that these features have been acquired through parasite adaptations acquired over long evolutionary time periods. PMID:26557685

  2. 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

  3. Human Plasmodium knowlesi Infection Detected by Rapid Diagnostic Tests for Malaria

    PubMed Central

    van Hellemond, Jaap J.; Rutten, Marijke; Koelewijn, Rob; Zeeman, Anne-Marie; Verweij, Jaco J.; Wismans, Pieter J.; Kocken, Clemens H.

    2009-01-01

    We describe a PCR-confirmed case of Plasmodium knowlesi infection with a high parasitemia level and clinical signs of severe malaria in a migrant worker from Malaysian Borneo in the Netherlands. Investigations showed that commercially available rapid antigen tests for detection of human Plasmodium infections can detect P. knowlesi infections in humans. PMID:19788819

  4. Submicroscopic Plasmodium falciparum infections in pregnancy in Ghana.

    PubMed

    Mockenhaupt, F P; Rong, B; Till, H; Eggelte, T A; Beck, S; Gyasi-Sarpong, C; Thompson, W N; Bienzle, U

    2000-03-01

    Malarial parasitaemia below the threshold of microscopy but detectable by polymerase chain reaction (PCR) assays is common in endemic regions. This study was conducted to examine prevalence, predictors, and effects of submicroscopic Plasmodium falciparum infections in pregnancy. In a cross-sectional study among 530 pregnant women in Ghana, plasmodial infections were assessed by microscopy and PCR assays. Concentrations of haemoglobin and C-reactive protein (CRP) were measured and antimalarial drugs (chloroquine, pyrimethamine) in urine were demonstrated by ELISA dipsticks. By microscopy, 32% of the women were found to harbour malaria parasites. This rate increased to 63% adding the results of the parasite-specific PCR. P. falciparum was present in all but one infection. With increasing gravidity, infection rates and parasite densities decreased and the proportions of submicroscopic parasitaemia among infected women grew. Correspondingly, anaemia, fever and evidence of inflammation (CRP > 0.6 mg/dl) were more frequent in primigravidae than in multigravidae. Antimalarial drugs were detected in 65% of the women and were associated with a reduced prevalence of P. falciparum infections and a raised proportion of submicroscopic parasitaemia. Both gravidity and antimalarial drug use were independent predictors of submicroscopic P. falciparum infections. These infections caused a slight reduction of Hb levels and considerably increased serum concentrations of CRP. Conventional microscopy underestimates the actual extent of malarial infections in pregnancy in endemic regions. Submicroscopic P. falciparum infections are frequent and may contribute to mild anaemia and inflammation in seemingly aparasitaemic pregnant women. PMID:10747278

  5. Major Histocompatibility Complex and Malaria: Focus on Plasmodium vivax Infection

    PubMed Central

    Lima-Junior, Josué da Costa; Pratt-Riccio, Lilian Rose

    2016-01-01

    The importance of host and parasite genetic factors in malaria resistance or susceptibility has been investigated since the middle of the last century. Nowadays, of all diseases that affect man, malaria still plays one of the highest levels of selective pressure on human genome. Susceptibility to malaria depends on exposure profile, epidemiological characteristics, and several components of the innate and adaptive immune system that influences the quality of the immune response generated during the Plasmodium lifecycle in the vertebrate host. But it is well known that the parasite’s enormous capacity of genetic variation in conjunction with the host genetics polymorphism is also associated with a wide spectrum of susceptibility degrees to complicated or severe forms of the disease. In this scenario, variations in genes of the major histocompatibility complex (MHC) associated with host resistance or susceptibility to malaria have been identified and used as markers in host–pathogen interaction studies, mainly those evaluating the impact on the immune response, acquisition of resistance, or increased susceptibility to infection or vulnerability to disease. However, due to the intense selective pressure, number of cases, and mortality rates, the majority of the reported associations reported concerned Plasmodium falciparum malaria. Studies on the MHC polymorphism and its association with Plasmodium vivax, which is the most widespread Plasmodium and the most prevalent species outside the African continent, are less frequent but equally important. Despite punctual contributions, there are accumulated evidences of human genetic control in P. vivax infection and disease. Herein, we review the current knowledge in the field of MHC and derived molecules (HLA Class I, Class II, TNF-α, LTA, BAT1, and CTL4) regarding P. vivax malaria. We discuss particularly the results of P. vivax studies on HLA class I and II polymorphisms in relation to host susceptibility, naturally

  6. Complexity of Infection and Genetic Diversity in Cambodian Plasmodium vivax

    PubMed Central

    Friedrich, Lindsey R.; Popovici, Jean; Kim, Saorin; Dysoley, Lek; Zimmerman, Peter A.; Menard, Didier; Serre, David

    2016-01-01

    Background Plasmodium vivax is the most widely distributed human malaria parasite with 2.9 billion people living in endemic areas. Despite intensive malaria control efforts, the proportion of cases attributed to P. vivax is increasing in many countries. Genetic analyses of the parasite population and its dynamics could provide an assessment of the efficacy of control efforts, but, unfortunately, these studies are limited in P. vivax by the lack of informative markers and high-throughput genotyping methods. Methodology/Principal Findings We developed a sequencing-based assay to simultaneously genotype more than 100 SNPs and applied this approach to ~500 P. vivax-infected individuals recruited across nine locations in Cambodia between 2004 and 2013. Our analyses showed that the vast majority of infections are polyclonal (92%) and that P. vivax displays high genetic diversity in Cambodia without apparent geographic stratification. Interestingly, our analyses also revealed that the proportion of monoclonal infections significantly increased between 2004 and 2013, possibly suggesting that malaria control strategies in Cambodia may be successfully affecting the parasite population. Conclusions/Significance Our findings demonstrate that this high-throughput genotyping assay is efficient in characterizing P. vivax diversity and can provide valuable insights to assess the efficacy of malaria elimination programs or to monitor the spread of specific parasites. PMID:27018585

  7. Interactive transcriptome analysis of malaria patients and infecting Plasmodium falciparum

    PubMed Central

    Yamagishi, Junya; Natori, Anna; Tolba, Mohammed E.M.; Mongan, Arthur E.; Sugimoto, Chihiro; Katayama, Toshiaki; Kawashima, Shuichi; Makalowski, Wojciech; Maeda, Ryuichiro; Eshita, Yuki; Tuda, Josef

    2014-01-01

    To understand the molecular mechanisms of parasitism in vivo, it is essential to elucidate how the transcriptomes of the human hosts and the infecting parasites affect one another. Here we report the RNA-seq analysis of 116 Indonesian patients infected with the malaria parasite Plasmodium falciparum (Pf). We extracted RNAs from their peripheral blood as a mixture of host and parasite transcripts and mapped the RNA-seq tags to the human and Pf reference genomes to separate the respective tags. We were thus able to simultaneously analyze expression patterns in both humans and parasites. We identified human and parasite genes and pathways that correlated with various clinical data, which may serve as primary targets for drug developments. Of particular importance, we revealed characteristic expression changes in the human innate immune response pathway genes including TLR2 and TICAM2 that correlated with the severity of the malaria infection. We also found a group of transcription regulatory factors, JUND, for example, and signaling molecules, TNFAIP3, for example, that were strongly correlated in the expression patterns of humans and parasites. We also identified several genetic variations in important anti-malaria drug resistance-related genes. Furthermore, we identified the genetic variations which are potentially associated with severe malaria symptoms both in humans and parasites. The newly generated data should collectively lay a unique foundation for understanding variable behaviors of the field malaria parasites, which are far more complex than those observed under laboratory conditions. PMID:25091627

  8. Anopheline species and their Plasmodium infection status in Aligarh, India.

    PubMed

    Saifi, Muheet Alam; Alyousif, Mohamed Saleh; Amoudi, Mikky A

    2016-09-01

    Malaria is a global issue and India contributes substantially to global malaria incidence. Information related to malaria vectors is very limited in Aligarh. The environmental and climatological situations permit the continual breeding of vectors in permanent breeding sites. This study was designed with the aim to screen all the anophelines species and possible malaria vectors in three different localities of Aligarh. Anopheles mosquitoes were collected from three different localities (Fort, Jalali and Tappal) during peak malaria transmission season (July to November) by using mouth aspirator and CDC light traps. Enzyme-linked immunosorbent assay (ELISA) was done to detect Plasmodium falciparum, Plasmodium vivax-210 and P. vivax-247 circumsporozoite proteins (CSP) from the collected female species. A total of 794 female anopheline mosquitoes belonging to 7 species were collected by different methods. Circumsporozoite protein-enzyme-linked immunosorbent assay was performed with 780 anopheline mosquitoes out of which 13 mosquitoes were positive in CSP-ELISA. Thus, the overall infection rate was 1.66% (13/780). Four (0.51%) mosquitoes belonging to three species were positive for P. falciparum, 7 (0.89%) mosquitoes belonging to three species were positive for VK 210 and 2 (0.25%) mosquitoes belonging to Anopheles culicifacies and Anopheles stephensi species were positive for VK 247. No mixed infection was found in this study. According to species, the highest infection rate was observed in An. culicifacies (7/288, 2.43%) followed by An. stephensi (2.40%) and Anopheles annularis (1.98%). An. culicifacies and An. stephensi were previously incriminated as malaria vectors in Aligarh. There was, however, no previous report in favor of infections in An. annularis in Aligarh. The on-going Malaria Control Program in India needs up to date information on malaria vectors. A major challenge is the lack of knowledge about vectors and their role in malaria transmission. Findings of

  9. Parasite-induced ER stress response in hepatocytes facilitates Plasmodium liver stage infection.

    PubMed

    Inácio, Patricia; Zuzarte-Luís, Vanessa; Ruivo, Margarida T G; Falkard, Brie; Nagaraj, Nagarjuna; Rooijers, Koos; Mann, Matthias; Mair, Gunnar; Fidock, David A; Mota, Maria M

    2015-08-01

    Upon infection of a mammalian host, Plasmodium parasites first replicate inside hepatocytes, generating thousands of new parasites. Although Plasmodium intra-hepatic development represents a substantial metabolic challenge to the host hepatocyte, how infected cells respond to and integrate this stress remains poorly understood. Here, we present proteomic and transcriptomic analyses, revealing that the endoplasmic reticulum (ER)-resident unfolded protein response (UPR) is activated in host hepatocytes upon Plasmodium berghei infection. The expression of XBP1s--the active form of the UPR mediator XBP1--and the liver-specific UPR mediator CREBH is induced by P. berghei infection in vivo. Furthermore, this UPR induction increases parasite liver burden. Altogether, our data suggest that ER stress is a central feature of P. berghei intra-hepatic development, contributing to the success of infection. PMID:26113366

  10. Parasite-induced ER stress response in hepatocytes facilitates Plasmodium liver stage infection

    PubMed Central

    Inácio, Patricia; Zuzarte-Luís, Vanessa; Ruivo, Margarida TG; Falkard, Brie; Nagaraj, Nagarjuna; Rooijers, Koos; Mann, Matthias; Mair, Gunnar; Fidock, David A; Mota, Maria M

    2015-01-01

    Upon infection of a mammalian host, Plasmodium parasites first replicate inside hepatocytes, generating thousands of new parasites. Although Plasmodium intra-hepatic development represents a substantial metabolic challenge to the host hepatocyte, how infected cells respond to and integrate this stress remains poorly understood. Here, we present proteomic and transcriptomic analyses, revealing that the endoplasmic reticulum (ER)-resident unfolded protein response (UPR) is activated in host hepatocytes upon Plasmodium berghei infection. The expression of XBP1s—the active form of the UPR mediator XBP1—and the liver-specific UPR mediator CREBH is induced by P. berghei infection in vivo. Furthermore, this UPR induction increases parasite liver burden. Altogether, our data suggest that ER stress is a central feature of P. berghei intra-hepatic development, contributing to the success of infection. PMID:26113366

  11. Infection with Wolbachia protects mosquitoes against Plasmodium-induced mortality in a natural system.

    PubMed

    Zélé, F; Nicot, A; Duron, O; Rivero, A

    2012-07-01

    In recent years, there has been a shift in the one host-one parasite paradigm with the realization that, in the field, most hosts are coinfected with multiple parasites. Coinfections are particularly relevant when the host is a vector of diseases, because multiple infections can have drastic consequences for parasite transmission at both the ecological and evolutionary timescales. Wolbachia pipientis is the most common parasitic microorganism in insects, and as such, it is of special interest for understanding the role of coinfections in the outcome of parasite infections. Here, we investigate whether Wolbachia can modulate the effect of Plasmodium on what is, arguably, the most important component of the vectorial capacity of mosquitoes: their longevity. For this purpose, and in contrast to recent studies that have focused on mosquito-Plasmodium and/or mosquito-Wolbachia combinations not found in nature, we work on a Wolbachia-mosquito-Plasmodium triad with a common evolutionary history. Our results show that Wolbachia protects mosquitoes from Plasmodium-induced mortality. The results are consistent across two different strains of Wolbachia and repeatable across two different experimental blocks. To our knowledge, this is the first time that such an effect has been shown for Plasmodium-infected mosquitoes and, in particular, in a natural Wolbachia-host combination. We discuss different mechanistic and evolutionary explanations for these results as well as their consequences for Plasmodium transmission. PMID:22533729

  12. First case of a naturally acquired human infection with Plasmodium cynomolgi

    PubMed Central

    2014-01-01

    Since 1960, a total of seven species of monkey malaria have been reported as transmissible to man by mosquito bite: Plasmodium cynomolgi, Plasmodium brasilianum, Plasmodium eylesi, Plasmodium knowlesi, Plasmodium inui, Plasmodium schwetzi and Plasmodium simium. With the exception of P. knowlesi, none of the other species has been found to infect humans in nature. In this report, it is described the first known case of a naturally acquired P. cynomolgi malaria in humans. The patient was a 39-year-old woman from a malaria-free area with no previous history of malaria or travel to endemic areas. Initially, malaria was diagnosed and identified as Plasmodium malariae/P. knowlesi by microscopy in the Terengganu State Health Department. Thick and thin blood films stained with 10% Giemsa were performed for microscopy examination. Molecular species identification was performed at the Institute for Medical Research (IMR, Malaysia) and in the Malaria & Emerging Parasitic Diseases Laboratory (MAPELAB, Spain) using different nested PCR methods. Microscopic re-examination in the IMR showed characteristics of Plasmodium vivax and was confirmed by a nested PCR assay developed by Snounou et al. Instead, a different PCR assay plus sequencing performed at the MAPELAB confirmed that the patient was infected with P. cynomolgi and not with P. vivax. This is the first report of human P. cynomolgi infection acquired in a natural way, but there might be more undiagnosed or misdiagnosed cases, since P. cynomolgi is morphologically indistinguishable from P. vivax, and one of the most used PCR methods for malaria infection detection may identify a P. cynomolgi infection as P. vivax. Simian Plasmodium species may routinely infect humans in Southeast Asia. New diagnostic methods are necessary to distinguish between the human and monkey malaria species. Further epidemiological studies, incriminating also the mosquito vector(s), must be performed to know the relevance of cynomolgi malaria and its

  13. 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

  14. Co-infection of Plasmodium vivax Malaria and Cytomegalovirus in an Immunocompetent Neonate.

    PubMed

    Chandelia, Sudha; Jain, Sarika

    2014-12-01

    Co-infections when occur can pose substantial diagnostic and treatment challenges for clinicians. In this case report we describe a neonate with co infection of plasmodium vivax malaria with Cytomegalovirus and discuss whether it can be the result of reactivation of one by the other infection postnatally or if these infections can affect and facilitate the transplacental transmission of each other from the mother. PMID:25653999

  15. One Episode of Self-Resolving Plasmodium yoelii Infection Transiently Exacerbates Chronic Mycobacterium tuberculosis Infection

    PubMed Central

    Blank, Jannike; Eggers, Lars; Behrends, Jochen; Jacobs, Thomas; Schneider, Bianca E.

    2016-01-01

    Malaria and tuberculosis (Tb) are two of the main causes of death from infectious diseases globally. The pathogenic agents, Plasmodium parasites and Mycobacterium tuberculosis, are co-endemic in many regions in the world, however, compared to other co-infections like HIV/Tb or helminth/Tb, malaria/Tb has been given less attention both in clinical and immunological studies. Due to the lack of sufficient human data, the impact of malaria on Tb and vice versa is difficult to estimate but co-infections are likely to occur very frequently. Due to its immunomodulatory properties malaria might be an underestimated risk factor for latent or active Tb patients particularly in high-endemic malaria settings were people experience reinfections very frequently. In the present study, we used the non-lethal strain of Plasmodium yoelii to investigate, how one episode of self-resolving malaria impact on a chronic M. tuberculosis infection. P. yoelii co-infection resulted in exacerbation of Tb disease as demonstrated by increased pathology and cellular infiltration of the lungs which coincided with elevated levels of pro- and anti-inflammatory mediators. T cell responses were not impaired in co-infected mice but enhanced and likely contributed to increased cytokine production. We found a slight but statistically significant increase in M. tuberculosis burden in co-infected animals and increased lung CFU was positively correlated with elevated levels of TNFα but not IL-10. Infection with P. yoelii induced the recruitment of a CD11c+ population into lungs and spleens of M. tuberculosis infected mice. CD11c+ cells isolated from P. yoelii infected spleens promoted survival and growth of M. tuberculosis in vitro. 170 days after P. yoelii infection changes in immunopathology and cellular immune responses were no longer apparent while M. tuberculosis numbers were still slightly higher in lungs, but not in spleens of co-infected mice. In conclusion, one episode of P. yoelii co-infection

  16. Multigenomic Delineation of Plasmodium Species of the Laverania Subgenus Infecting Wild-Living Chimpanzees and Gorillas.

    PubMed

    Liu, Weimin; Sundararaman, Sesh A; Loy, Dorothy E; Learn, Gerald H; Li, Yingying; Plenderleith, Lindsey J; Ndjango, Jean-Bosco N; Speede, Sheri; Atencia, Rebeca; Cox, Debby; Shaw, George M; Ayouba, Ahidjo; Peeters, Martine; Rayner, Julian C; Hahn, Beatrice H; Sharp, Paul M

    2016-01-01

    Plasmodium falciparum, the major cause of malaria morbidity and mortality worldwide, is only distantly related to other human malaria parasites and has thus been placed in a separate subgenus, termed Laverania Parasites morphologically similar to P. falciparum have been identified in African apes, but only one other Laverania species, Plasmodium reichenowi from chimpanzees, has been formally described. Although recent studies have pointed to the existence of additional Laverania species, their precise number and host associations remain uncertain, primarily because of limited sampling and a paucity of parasite sequences other than from mitochondrial DNA. To address this, we used limiting dilution polymerase chain reaction to amplify additional parasite sequences from a large number of chimpanzee and gorilla blood and fecal samples collected at two sanctuaries and 30 field sites across equatorial Africa. Phylogenetic analyses of more than 2,000 new sequences derived from the mitochondrial, nuclear, and apicoplast genomes revealed six divergent and well-supported clades within the Laverania parasite group. Although two of these clades exhibited deep subdivisions in phylogenies estimated from organelle gene sequences, these sublineages were geographically defined and not present in trees from four unlinked nuclear loci. This greatly expanded sequence data set thus confirms six, and not seven or more, ape Laverania species, of which P. reichenowi, Plasmodium gaboni, and Plasmodium billcollinsi only infect chimpanzees, whereas Plasmodium praefalciparum, Plasmodium adleri, and Pladmodium blacklocki only infect gorillas. The new sequence data also confirm the P. praefalciparum origin of human P. falciparum. PMID:27289102

  17. Multigenomic Delineation of Plasmodium Species of the Laverania Subgenus Infecting Wild-Living Chimpanzees and Gorillas

    PubMed Central

    Liu, Weimin; Sundararaman, Sesh A.; Loy, Dorothy E.; Learn, Gerald H.; Li, Yingying; Plenderleith, Lindsey J.; Ndjango, Jean-Bosco N.; Speede, Sheri; Atencia, Rebeca; Cox, Debby; Shaw, George M.; Ayouba, Ahidjo; Peeters, Martine; Rayner, Julian C.; Hahn, Beatrice H.; Sharp, Paul M.

    2016-01-01

    Plasmodium falciparum, the major cause of malaria morbidity and mortality worldwide, is only distantly related to other human malaria parasites and has thus been placed in a separate subgenus, termed Laverania. Parasites morphologically similar to P. falciparum have been identified in African apes, but only one other Laverania species, Plasmodium reichenowi from chimpanzees, has been formally described. Although recent studies have pointed to the existence of additional Laverania species, their precise number and host associations remain uncertain, primarily because of limited sampling and a paucity of parasite sequences other than from mitochondrial DNA. To address this, we used limiting dilution polymerase chain reaction to amplify additional parasite sequences from a large number of chimpanzee and gorilla blood and fecal samples collected at two sanctuaries and 30 field sites across equatorial Africa. Phylogenetic analyses of more than 2,000 new sequences derived from the mitochondrial, nuclear, and apicoplast genomes revealed six divergent and well-supported clades within the Laverania parasite group. Although two of these clades exhibited deep subdivisions in phylogenies estimated from organelle gene sequences, these sublineages were geographically defined and not present in trees from four unlinked nuclear loci. This greatly expanded sequence data set thus confirms six, and not seven or more, ape Laverania species, of which P. reichenowi, Plasmodium gaboni, and Plasmodium billcollinsi only infect chimpanzees, whereas Plasmodium praefalciparum, Plasmodium adleri, and Pladmodium blacklocki only infect gorillas. The new sequence data also confirm the P. praefalciparum origin of human P. falciparum. PMID:27289102

  18. Complication of Corticosteroid Treatment by Acute Plasmodium malariae Infection Confirmed by Small-Subunit rRNA Sequencing▿

    PubMed Central

    To, Kelvin K. W.; Teng, Jade L. L.; Wong, Samson S. Y.; Ngan, Antonio H. Y.; Yuen, Kwok-Yung; Woo, Patrick C. Y.

    2010-01-01

    We report a case of acute Plasmodium malariae infection complicating corticosteroid treatment for membranoproliferative glomerulonephritis in a patient from an area where P. malariae infection is not endemic. A peripheral blood smear showed typical band-form trophozoites compatible with P. malariae or Plasmodium knowlesi. SSU rRNA sequencing confirmed the identity to be P. malariae. PMID:20739487

  19. Energy metabolism affects susceptibility of Anopheles gambiae mosquitoes to Plasmodium infection.

    PubMed

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

    2011-06-01

    Previous studies showed that Anopheles gambiae L3-5 females, which are refractory (R) to Plasmodium infection, express higher levels of genes involved in redox-metabolism and mitochondrial respiration than susceptible (S) G3 females. Our studies revealed that R females have reduced longevity, faster utilization of lipid reserves, impaired mitochondrial state-3 respiration, increased rate of mitochondrial electron leak and higher expression levels of several glycolytic enzyme genes. Furthermore, when state-3 respiration was reduced in S females by silencing expression of the adenine nucleotide translocator (ANT), hydrogen peroxide generation was higher and the mRNA levels of lactate dehydrogenase increased in the midgut, while the prevalence and intensity of Plasmodium berghei infection were significantly reduced. We conclude that there are broad metabolic differences between R and S An. gambiae mosquitoes that influence their susceptibility to Plasmodium infection. PMID:21320598

  20. Plasmodium Infection Promotes Genomic Instability and AID Dependent B Cell Lymphoma

    PubMed Central

    Robbiani, Davide F.; Deroubaix, Stephanie; Feldhahn, Niklas; Oliveira, Thiago Y.; Callen, Elsa; Wang, Qiao; Jankovic, Mila; Silva, Israel T.; Rommel, Philipp C.; Bosque, David; Eisenreich, Tom; Nussenzweig, André; Nussenzweig, Michel C.

    2015-01-01

    Summary Chronic infection with Plasmodium falciparum was epidemiologically associated with endemic Burkitt’s lymphoma, a mature B cell cancer characterized by chromosome translocation between the c-myc oncogene and Igh, over 50 years ago. Whether infection promotes B cell lymphoma, and if so by what mechanism remains unknown. To investigate the relationship between parasitic disease and lymphomagenesis we used Plasmodium chabaudi (Pc) to produce chronic malaria infection in mice. Pc induces prolonged expansion of germinal centers (GCs), unique compartments where B cells undergo rapid clonal expansion and express activation-induced cytidine deaminase (AID), a DNA mutator. GC B cells elicited during Pc infection suffer widespread DNA damage leading to chromosome translocations. Although infection does not change the overall rate, it modifies lymphomagenesis to favor mature B cell lymphomas that are AID dependent and show chromosome translocations. Thus, malaria infection favors mature B cell cancers by eliciting protracted AID expression in GC B cells. PMID:26276629

  1. Mixed Species Flock, Nest Height, and Elevation Partially Explain Avian Haemoparasite Prevalence in Colombia

    PubMed Central

    González, Angie D.; Matta, Nubia E.; Ellis, Vincenzo A.; Miller, Eliot T.; Ricklefs, Robert E.; Gutiérrez, H. Rafael

    2014-01-01

    The high avian biodiversity present in the Neotropical region offers a great opportunity to explore the ecology of host-parasite relationships. We present a survey of avian haemoparasites in a megadiverse country and explore how parasite prevalences are related to physical and ecological host characteristics. Using light microscopy, we documented the presence of haemoparasites in over 2000 individuals belonging to 246 species of wild birds, from nine localities and several ecosystems of Colombia. We analysed the prevalence of six avian haemoparasite taxa in relation to elevation and the following host traits: nest height, nest type, foraging strata, primary diet, sociality, migratory behaviour, and participation in mixed species flocks. Our analyses indicate significant associations between both mixed species flocks and nest height and Haemoproteus and Leucocytozoon prevalence. The prevalence of Leucocytozoon increased with elevation, whereas the prevalence of Trypanosoma and microfilariae decreased. Plasmodium and Haemoproteus prevalence did not vary significantly with elevation; in fact, both parasites were found up to 3300m above sea level. The distribution of parasite prevalence across the phylogeny of bird species included in this study showed little host phylogenetic signal indicating that infection rates in this system are evolutionarily labile. Vector distribution as well as the biology of transmission and the maintenance of populations of avian haemoparasites deserve more detailed study in this system. PMID:24950223

  2. Symptoms and Immune Markers in Plasmodium/Dengue Virus Co-infection Compared with Mono-infection with Either in Peru

    PubMed Central

    Halsey, Eric S.; Baldeviano, G. Christian; Edgel, Kimberly A.; Vilcarromero, Stalin; Sihuincha, Moises; Lescano, Andres G.

    2016-01-01

    Background Malaria and dengue are two of the most common vector-borne diseases in the world, but co-infection is rarely described, and immunologic comparisons of co-infection with mono-infection are lacking. Methodology and Principal Findings We collected symptom histories and blood specimens from subjects in a febrile illness surveillance study conducted in Iquitos and Puerto Maldonado, Peru, between 2002–2011. Nineteen symptoms and 18 immune markers at presentation were compared among those with co-infection with Plasmodium/dengue virus (DENV), Plasmodium mono-infection, and DENV mono-infection. Seventeen subjects were identified as having Plasmodium/DENV co-infection and were retrospectively matched with 51 DENV mono-infected and 44 Plasmodium mono-infected subjects. Those with Plasmodium mono-infection had higher levels of IL-4, IL-6, IL-10, IL-12, IL-13, IL-17A, IFN-γ, and MIP1-α/CCL3 compared with DENV mono-infection or co-infection; those with Plasmodium mono-infection had more cough than those with DENV mono-infection. Subjects with DENV mono-infection had higher levels of TGF-β1 and more myalgia than those with Plasmodium mono-infection. No symptom was more common and no immune marker level was higher in the co-infected group, which had similar findings to the DENV mono-infected subjects. Conclusions/Significance Compared with mono-infection with either pathogen, Plasmodium/DENV co-infection was not associated with worse disease and resembled DENV mono-infection in both symptom frequency and immune marker level. PMID:27128316

  3. Acute Disseminated Encephalomyelitis After Plasmodium Vivax Infection: Case Report and Review of Literature

    PubMed Central

    Sidhu, Jasmeet; Maheshwari, Anu; Gupta, Raju; Devgan, Veena

    2015-01-01

    Acute demyelinating encephalomyelitis (ADEM) usually occurs after viral infections or vaccination. Its occurrence after Plasmodium vivax infection is extremely uncommon. We report the case of an 8-year-old girl who had choreo-athetoid movements and ataxia after recovery from P.vivax infection. Diagnosis of ADEM was made on the basis of magnetic resonance imaging findings. The child responded to corticosteroids with complete neurological recovery. PMID:26266032

  4. Asparagine requirement in Plasmodium berghei as a target to prevent malaria transmission and liver infections.

    PubMed

    Nagaraj, Viswanathan A; Mukhi, Dhanunjay; Sathishkumar, Vinayagam; Subramani, Pradeep A; Ghosh, Susanta K; Pandey, Rajeev R; Shetty, Manjunatha C; Padmanaban, Govindarajan

    2015-01-01

    The proteins of Plasmodium, the malaria parasite, are strikingly rich in asparagine. Plasmodium depends primarily on host haemoglobin degradation for amino acids and has a rudimentary pathway for amino acid biosynthesis, but retains a gene encoding asparagine synthetase (AS). Here we show that deletion of AS in Plasmodium berghei (Pb) delays the asexual- and liver-stage development with substantial reduction in the formation of ookinetes, oocysts and sporozoites in mosquitoes. In the absence of asparagine synthesis, extracellular asparagine supports suboptimal survival of PbAS knockout (KO) parasites. Depletion of blood asparagine levels by treating PbASKO-infected mice with asparaginase completely prevents the development of liver stages, exflagellation of male gametocytes and the subsequent formation of sexual stages. In vivo supplementation of asparagine in mice restores the exflagellation of PbASKO parasites. Thus, the parasite life cycle has an absolute requirement for asparagine, which we propose could be targeted to prevent malaria transmission and liver infections. PMID:26531182

  5. Asparagine requirement in Plasmodium berghei as a target to prevent malaria transmission and liver infections

    PubMed Central

    Nagaraj, Viswanathan A.; Mukhi, Dhanunjay; Sathishkumar, Vinayagam; Subramani, Pradeep A.; Ghosh, Susanta K.; Pandey, Rajeev R.; Shetty, Manjunatha C.; Padmanaban, Govindarajan

    2015-01-01

    The proteins of Plasmodium, the malaria parasite, are strikingly rich in asparagine. Plasmodium depends primarily on host haemoglobin degradation for amino acids and has a rudimentary pathway for amino acid biosynthesis, but retains a gene encoding asparagine synthetase (AS). Here we show that deletion of AS in Plasmodium berghei (Pb) delays the asexual- and liver-stage development with substantial reduction in the formation of ookinetes, oocysts and sporozoites in mosquitoes. In the absence of asparagine synthesis, extracellular asparagine supports suboptimal survival of PbAS knockout (KO) parasites. Depletion of blood asparagine levels by treating PbASKO-infected mice with asparaginase completely prevents the development of liver stages, exflagellation of male gametocytes and the subsequent formation of sexual stages. In vivo supplementation of asparagine in mice restores the exflagellation of PbASKO parasites. Thus, the parasite life cycle has an absolute requirement for asparagine, which we propose could be targeted to prevent malaria transmission and liver infections. PMID:26531182

  6. Spatiotemporal Dynamics and Demographic Profiles of Imported Plasmodium falciparum and Plasmodium vivax Infections in Ontario, Canada (1990–2009)

    PubMed Central

    Nelder, Mark P.; Russell, Curtis; Williams, Dawn; Johnson, Karen; Li, Lennon; Baker, Stacey L.; Marshall, Sean; Bhanich-Supapol, Wendy; Pillai, Dylan R.; Ralevski, Filip

    2013-01-01

    We examined malaria cases reported to Ontario’s public health surveillance systems from 1990 through 2009 to determine how temporal scale (longitudinal, seasonal), spatial scale (provincial, health unit), and demography (gender, age) contribute to Plasmodium infection in Ontario travellers. Our retrospective study included 4,551 confirmed cases of imported malaria reported throughout Ontario, with additional analysis at the local health unit level (i.e., Ottawa, Peel, and Toronto). During the 20-year period, Plasmodium vivax accounted for 50.6% of all cases, P. falciparum (38.6%), Plasmodium sp. (6.0%), P. ovale (3.1%), and P. malariae (1.8%). During the first ten years of the study (1990–1999), P. vivax (64% of all cases) was the dominant agent, followed by P. falciparum (28%); however, during the second ten years (2000–2009) the situation reversed and P. falciparum (55%) dominated, followed by P. vivax (30%). The prevalence of P. falciparum and P. vivax cases varied spatially (e.g., P. falciparum more prevalent in Toronto, P. vivax more prevalent in Peel), temporally (e.g. P. falciparum incidence increased during the 20-year study), and demographically (e.g. preponderance of male cases). Infection rates per 100,000 international travellers were estimated: rates of infection were 2× higher in males compared to females; rates associated with travel to Africa were 37× higher compared to travel to Asia and 126× higher compared to travel to the Americas; rates of infection were 2.3–3.5× higher in June and July compared to October through March; and rates of infection were highest in those 65–69 years old. Where exposure country was reported, 71% of P. falciparum cases reported exposure in Ghana or Nigeria and 63% of P. vivax cases reported exposure in India. Our study provides insights toward improving pre-travel programs for Ontarians visiting malaria-endemic regions and underscores the changing epidemiology of imported malaria in the province. PMID

  7. Spatiotemporal dynamics and demographic profiles of imported Plasmodium falciparum and Plasmodium vivax infections in Ontario, Canada (1990-2009).

    PubMed

    Nelder, Mark P; Russell, Curtis; Williams, Dawn; Johnson, Karen; Li, Lennon; Baker, Stacey L; Marshall, Sean; Bhanich-Supapol, Wendy; Pillai, Dylan R; Ralevski, Filip

    2013-01-01

    We examined malaria cases reported to Ontario's public health surveillance systems from 1990 through 2009 to determine how temporal scale (longitudinal, seasonal), spatial scale (provincial, health unit), and demography (gender, age) contribute to Plasmodium infection in Ontario travellers. Our retrospective study included 4,551 confirmed cases of imported malaria reported throughout Ontario, with additional analysis at the local health unit level (i.e., Ottawa, Peel, and Toronto). During the 20-year period, Plasmodium vivax accounted for 50.6% of all cases, P. falciparum (38.6%), Plasmodium sp. (6.0%), P. ovale (3.1%), and P. malariae (1.8%). During the first ten years of the study (1990-1999), P. vivax (64% of all cases) was the dominant agent, followed by P. falciparum (28%); however, during the second ten years (2000-2009) the situation reversed and P. falciparum (55%) dominated, followed by P. vivax (30%). The prevalence of P. falciparum and P. vivax cases varied spatially (e.g., P. falciparum more prevalent in Toronto, P. vivax more prevalent in Peel), temporally (e.g. P. falciparum incidence increased during the 20-year study), and demographically (e.g. preponderance of male cases). Infection rates per 100,000 international travellers were estimated: rates of infection were 2× higher in males compared to females; rates associated with travel to Africa were 37× higher compared to travel to Asia and 126× higher compared to travel to the Americas; rates of infection were 2.3-3.5× higher in June and July compared to October through March; and rates of infection were highest in those 65-69 years old. Where exposure country was reported, 71% of P. falciparum cases reported exposure in Ghana or Nigeria and 63% of P. vivax cases reported exposure in India. Our study provides insights toward improving pre-travel programs for Ontarians visiting malaria-endemic regions and underscores the changing epidemiology of imported malaria in the province. PMID:24098780

  8. Asymptomatic Plasmodium Infections in Children in Low Malaria Transmission Setting, Southwestern Uganda1

    PubMed Central

    Roh, Michelle E.; Oyet, Caesar; Orikiriza, Patrick; Wade, Martina; Kiwanuka, Gertrude N.; Mwanga-Amumpaire, Juliet; Boum, Yap

    2016-01-01

    A survey of asymptomatic children in Uganda showed Plasmodium malariae and P. falciparum parasites in 45% and 55% of microscopy-positive samples, respectively. Although 36% of microscopy-positive samples were negative by rapid diagnostic test, 75% showed P. malariae or P. ovale parasites by PCR, indicating that routine diagnostic testing misses many non–P. falciparum malarial infections. PMID:27434741

  9. Asymptomatic Plasmodium Infections in Children in Low Malaria Transmission Setting, Southwestern Uganda(1).

    PubMed

    Roh, Michelle E; Oyet, Caesar; Orikiriza, Patrick; Wade, Martina; Kiwanuka, Gertrude N; Mwanga-Amumpaire, Juliet; Parikh, Sunil; Boum, Yap

    2016-08-01

    A survey of asymptomatic children in Uganda showed Plasmodium malariae and P. falciparum parasites in 45% and 55% of microscopy-positive samples, respectively. Although 36% of microscopy-positive samples were negative by rapid diagnostic test, 75% showed P. malariae or P. ovale parasites by PCR, indicating that routine diagnostic testing misses many non-P. falciparum malarial infections. PMID:27434741

  10. Infection and Co-infection with Helminths and Plasmodium among School Children in Côte d’Ivoire: Results from a National Cross-Sectional Survey

    PubMed Central

    Yapi, Richard B.; Hürlimann, Eveline; Houngbedji, Clarisse A.; Ndri, Prisca B.; Silué, Kigbafori D.; Soro, Gotianwa; Kouamé, Ferdinand N.; Vounatsou, Penelope; Fürst, Thomas; N’Goran, Eliézer K.; Utzinger, Jürg; Raso, Giovanna

    2014-01-01

    Background Helminth infection and malaria remain major causes of ill-health in the tropics and subtropics. There are several shared risk factors (e.g., poverty), and hence, helminth infection and malaria overlap geographically and temporally. However, the extent and consequences of helminth-Plasmodium co-infection at different spatial scales are poorly understood. Methodology This study was conducted in 92 schools across Côte d’Ivoire during the dry season, from November 2011 to February 2012. School children provided blood samples for detection of Plasmodium infection, stool samples for diagnosis of soil-transmitted helminth (STH) and Schistosoma mansoni infections, and urine samples for appraisal of Schistosoma haematobium infection. A questionnaire was administered to obtain demographic, socioeconomic, and behavioral data. Multinomial regression models were utilized to determine risk factors for STH-Plasmodium and Schistosoma-Plasmodium co-infection. Principal Findings Complete parasitological and questionnaire data were available for 5,104 children aged 5-16 years. 26.2% of the children were infected with any helminth species, whilst the prevalence of Plasmodium infection was 63.3%. STH-Plasmodium co-infection was detected in 13.5% and Schistosoma-Plasmodium in 5.6% of the children. Multinomial regression analysis revealed that boys, children aged 10 years and above, and activities involving close contact to water were significantly and positively associated with STH-Plasmodium co-infection. Boys, wells as source of drinking water, and water contact were significantly and positively associated with Schistosoma-Plasmodium co-infection. Access to latrines, deworming, higher socioeconomic status, and living in urban settings were negatively associated with STH-Plasmodium co-infection; whilst use of deworming drugs and access to modern latrines were negatively associated with Schistosoma-Plasmodium co-infection. Conclusions/Significance More than 60% of the

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

    PubMed Central

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

    2009-01-01

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

  12. Schistosoma mansoni Infection Impairs Antimalaria Treatment and Immune Responses of Rhesus Macaques Infected with Mosquito-Borne Plasmodium coatneyi

    PubMed Central

    Semenya, Amma A.; Sullivan, JoAnn S.; Barnwell, John W.

    2012-01-01

    Malaria and schistosomiasis are the world's two most important parasitic infections in terms of distribution, morbidity, and mortality. In areas where Plasmodium and Schistosoma species are both endemic, coinfections are commonplace. Mouse models demonstrate that schistosomiasis worsens a malaria infection; however, just as mice and humans differ greatly, the murine-infecting Plasmodium species differ as much from those that infect humans. Research into human coinfections (Schistosoma haematobium-Plasmodium falciparum versus Schistosoma mansoni-P. falciparum) has produced conflicting results. The rhesus macaque model provides a helpful tool for understanding the role of S. mansoni on malaria parasitemia and antimalarial immune responses using Plasmodium coatneyi, a malaria species that closely resembles P. falciparum infection in humans. Eight rhesus macaques were exposed to S. mansoni cercariae. Eight weeks later, these animals plus 8 additional macaques were exposed to malaria either through bites of infected mosquitos or intravenous inoculation. When malaria infection was initiated from mosquito bites, coinfected animals displayed increased malaria parasitemia, decreased hematocrit levels, and suppressed malaria-specific antibody responses compared to those of malaria infection alone. However, macaques infected by intravenous inoculation with erythrocytic-stage parasites did not display these same differences in parasitemia, hematocrit, or antibody responses between the two groups. Use of the macaque model provides information that begins to unravel differences in pathological and immunological outcomes observed between humans with P. falciparum that are coinfected with S. mansoni or S. haematobium. Our results suggest that migration of malaria parasites through livers harboring schistosome eggs may alter host immune responses and infection outcomes. PMID:22907811

  13. 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

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

    PubMed

    Vera, Omaira; Brelas de Brito, Paula; Albrecht, Letusa; Martins-Campos, Keillen Monick; Pimenta, Paulo F P; Monteiro, Wuelton M; Lacerda, Marcus V G; Lopes, Stefanie C P; Costa, Fabio T M

    2015-10-01

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

  15. 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. PMID:26061150

  16. Partnering Parasites: Evidence of Synergism between Heavy Schistosoma haematobium and Plasmodium Species Infections in Kenyan Children

    PubMed Central

    Florey, Lia S.; King, Charles H.; Van Dyke, Melissa K.; Muchiri, Eric M.; Mungai, Peter L.; Zimmerman, Peter A.; Wilson, Mark L.

    2012-01-01

    Background Residents of resource-poor tropical countries carry heavy burdens of concurrent parasitic infections, leading to high rates of morbidity and mortality. This study was undertaken to help identify the social and environmental determinants of multiple parasite infection in one such community. Methodology/Principal Findings Residents of Kingwede, Kenya aged 8 years and older were tested for presence and intensity of S. haematobium and Plasmodium spp. infections in a cross-sectional, household-based, community survey. Using General Estimating Equation (GEE) models, social and environmental determinants associated with patterns of co-infection were identified, with age being one of the most important factors. Children had 9.3 times the odds of co-infection compared to adults (95%CI = 5.3–16.3). Even after controlling for age, socio-economic position, and other correlates of co-infection, intense concomitant infections with the two parasites were found to cluster in a subset of individuals: the odds of heavy vs. light S. haematobium infection increased with increasing Plasmodium infection intensity suggesting the importance of unmeasured biological factors in determining intensity of co-infection. Conclusions/Significance Children in this community are more likely to be infected with multiple parasites than are adults and should therefore be targeted for prevention and control interventions. More importantly, heavy infections with multiple parasite species appear to cluster within a subset of individuals. Further studies focusing on these most vulnerable people are warranted. PMID:22848765

  17. An Atypical Splenic B Cell Progenitor Population Supports Antibody Production during Plasmodium Infection in Mice.

    PubMed

    Ghosh, Debopam; Wikenheiser, Daniel J; Kennedy, Brian; McGovern, Kathryn E; Stuart, Johnasha D; Wilson, Emma H; Stumhofer, Jason S

    2016-09-01

    Hematopoietic stem and progenitor cells (HSPCs) function to replenish the immune cell repertoire under steady-state conditions and in response to inflammation due to infection or stress. Whereas the bone marrow serves as the primary niche for hematopoiesis, extramedullary mobilization and differentiation of HSPCs occur in the spleen during acute Plasmodium infection, a critical step in the host immune response. In this study, we identified an atypical HSPC population in the spleen of C57BL/6 mice, with a lineage(-)Sca-1(+)c-Kit(-) (LSK(-)) phenotype that proliferates in response to infection with nonlethal Plasmodium yoelii 17X. Infection-derived LSK(-) cells upon transfer into naive congenic mice were found to differentiate predominantly into mature follicular B cells. However, when transferred into infection-matched hosts, infection-derived LSK(-) cells gave rise to B cells capable of entering into a germinal center reaction, and they developed into memory B cells and Ab-secreting cells that were capable of producing parasite-specific Abs. Differentiation of LSK(-) cells into B cells in vitro was enhanced in the presence of parasitized RBC lysate, suggesting that LSK(-) cells expand and differentiate in direct response to the parasite. However, the ability of LSK(-) cells to differentiate into B cells was not dependent on MyD88, as myd88(-/-) LSK(-) cell expansion and differentiation remained unaffected after Plasmodium infection. Collectively, these data identify a population of atypical lymphoid progenitors that differentiate into B lymphocytes in the spleen and are capable of contributing to the ongoing humoral immune response against Plasmodium infection. PMID:27448588

  18. 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.

  19. The exported Plasmodium berghei protein IBIS1 delineates membranous structures in infected red blood cells

    PubMed Central

    Ingmundson, Alyssa; Nahar, Carolin; Brinkmann, Volker; Lehmann, Maik J; Matuschewski, Kai

    2012-01-01

    Summary The importance of pathogen-induced host cell remodelling has been well established for red blood cell infection by the human malaria parasite Plasmodium falciparum. Exported parasite-encoded proteins, which often possess a signature motif, termed Plasmodium export element (PEXEL) or host-targeting (HT) signal, are critical for the extensive red blood cell modifications. To what extent remodelling of erythrocyte membranes also occurs in non-primate hosts and whether it is in fact a hallmark of all mammalian Plasmodium parasites remains elusive. Here we characterize a novel Plasmodium berghei PEXEL/HT-containing protein, which we term IBIS1. Temporal expression and spatial localization determined by fluorescent tagging revealed the presence of IBIS1 at the parasite/host interface during both liver and blood stages of infection. Targeted deletion of the IBIS1 protein revealed a mild impairment of intra-erythrocytic growth indicating a role for these structures in the rapid expansion of the parasite population in the blood in vivo. In red blood cells, the protein localizes to dynamic, punctate structures external to the parasite. Biochemical and microscopic data revealed that these intra-erythrocytic P. berghei-induced structures (IBIS) are membranous indicating that P. berghei, like P. falciparum, creates an intracellular membranous network in infected red blood cells. PMID:22329949

  20. 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

    2016-01-01

    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-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. PMID:27432257

  1. 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

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

    PubMed

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

    2013-01-01

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

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

    PubMed Central

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

    2013-01-01

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

  4. In Vitro Alterations Do Not Reflect a Requirement for Host Cell Cycle Progression during Plasmodium Liver Stage Infection

    PubMed Central

    Hanson, Kirsten K.; March, Sandra; Ng, Shengyong; Bhatia, Sangeeta N.

    2014-01-01

    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. PMID:25416236

  5. Tissue-Resident CD169(+) Macrophages Form a Crucial Front Line against Plasmodium Infection.

    PubMed

    Gupta, Pravesh; Lai, Si Min; Sheng, Jianpeng; Tetlak, Piotr; Balachander, Akhila; Claser, Carla; Renia, Laurent; Karjalainen, Klaus; Ruedl, Christiane

    2016-08-01

    Tissue macrophages exhibit diverse functions, ranging from the maintenance of tissue homeostasis, including clearance of senescent erythrocytes and cell debris, to modulation of inflammation and immunity. Their contribution to the control of blood-stage malaria remains unclear. Here, we show that in the absence of tissue-resident CD169(+) macrophages, Plasmodium berghei ANKA (PbA) infection results in significantly increased parasite sequestration, leading to vascular occlusion and leakage and augmented tissue deposition of the malarial pigment hemozoin. This leads to widespread tissue damage culminating in multiple organ inflammation. Thus, the capacity of CD169(+) macrophages to contain the parasite burden and its sequestration into different tissues and to limit infection-induced inflammation is crucial to mitigating Plasmodium infection and pathogenesis. PMID:27477286

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

    PubMed Central

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

    2011-01-01

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

  7. Avian Plasmodium infection in field-collected mosquitoes during 2012-2013 in Tarlac, Philippines.

    PubMed

    Chen, Tien-Huang; Aure, Wilfredo E; Cruz, Estrella Irlandez; Malbas, Fedelino F; Teng, Hwa-Jen; Lu, Liang-Chen; Kim, Kyeong Soon; Tsuda, Yoshio; Shu, Pei-Yun

    2015-12-01

    Global warming threatens to increase the spread and prevalence of mosquito-transmitted diseases. Certain pathogens may be carried by migratory birds and transmitted to local mosquito populations. Mosquitoes were collected in the northern Philippines during bird migration seasons to detect avian malaria parasites as well as for the identification of potential vector species and the estimation of infections among local mosquito populations. We used the nested PCR to detect the avian malaria species. Culex vishnui (47.6%) was the most abundant species collected and Cx. tritaeniorhynchus (13.8%) was the second most abundant. Avian Plasmodium parasites were found in eight mosquito species, for which the infection rates were between 0.5% and 6.2%. The six Plasmodium genetic lineages found in this study included P. juxtanucleare -GALLUS02, Tacy7 (Donana04), CXBIT01, Plasmodium species LIN2 New Zealand, and two unclassified lineages. The potential mosquito vectors for avian Plasmodium parasites in the Philippines were Cq. crassipes, Cx. fuscocephala, Cx. quinquefasciatus, Cx. sitiens, Cx. vishnui, and Ma. Uniformis; two major genetic lineages, P. juxtanucleare and Tacy7, were identified. PMID:26611975

  8. Hemoparasites in a wild primate: Infection patterns suggest interaction of Plasmodium and Babesia in a lemur species.

    PubMed

    Springer, Andrea; Fichtel, Claudia; Calvignac-Spencer, Sébastien; Leendertz, Fabian H; Kappeler, Peter M

    2015-12-01

    Hemoparasites can cause serious morbidity in humans and animals and often involve wildlife reservoirs. Understanding patterns of hemoparasite infections in natural populations can therefore inform about emerging disease risks, especially in the light of climate change and human disruption of natural ecosystems. We investigated the effects of host age, sex, host group size and season on infection patterns of Plasmodium sp., Babesia sp. and filarial nematodes in a population of wild Malagasy primates, Verreaux's sifakas (Propithecus verreauxi), as well as the effects of these infections on hematological variables. We tested 45 blood samples from 36 individuals and identified two species of Plasmodium, one species of Babesia and two species of filarial nematodes. Plasmodium spp. and Babesia sp. infections showed opposite patterns of age-dependency, with babesiosis being prevalent among young animals, while older animals were infected with Plasmodium sp. In addition, Babesia sp. infection was a statistically significant negative predictor of Plasmodium sp. infection. These results suggest that Plasmodium and Babesia parasites may interact within the host, either through cross-immunity or via resource competition, so that Plasmodium infections can only establish after babesiosis has resolved. We found no effects of host sex, host group size and season on hemoparasite infections. Infections showed high prevalences and did not influence hematological variables. This preliminary evidence supports the impression that the hosts and parasites considered in this study appear to be well-adapted to each other, resulting in persistent infections with low pathogenic and probably low zoonotic potential. Our results illustrate the crucial role of biodiversity in host-parasite relationships, specifically how within-host pathogen diversity may regulate the abundance of parasites. PMID:26767166

  9. Hemoparasites in a wild primate: Infection patterns suggest interaction of Plasmodium and Babesia in a lemur species☆

    PubMed Central

    Springer, Andrea; Fichtel, Claudia; Calvignac-Spencer, Sébastien; Leendertz, Fabian H.; Kappeler, Peter M.

    2015-01-01

    Hemoparasites can cause serious morbidity in humans and animals and often involve wildlife reservoirs. Understanding patterns of hemoparasite infections in natural populations can therefore inform about emerging disease risks, especially in the light of climate change and human disruption of natural ecosystems. We investigated the effects of host age, sex, host group size and season on infection patterns of Plasmodium sp., Babesia sp. and filarial nematodes in a population of wild Malagasy primates, Verreaux's sifakas (Propithecus verreauxi), as well as the effects of these infections on hematological variables. We tested 45 blood samples from 36 individuals and identified two species of Plasmodium, one species of Babesia and two species of filarial nematodes. Plasmodium spp. and Babesia sp. infections showed opposite patterns of age-dependency, with babesiosis being prevalent among young animals, while older animals were infected with Plasmodium sp. In addition, Babesia sp. infection was a statistically significant negative predictor of Plasmodium sp. infection. These results suggest that Plasmodium and Babesia parasites may interact within the host, either through cross-immunity or via resource competition, so that Plasmodium infections can only establish after babesiosis has resolved. We found no effects of host sex, host group size and season on hemoparasite infections. Infections showed high prevalences and did not influence hematological variables. This preliminary evidence supports the impression that the hosts and parasites considered in this study appear to be well-adapted to each other, resulting in persistent infections with low pathogenic and probably low zoonotic potential. Our results illustrate the crucial role of biodiversity in host-parasite relationships, specifically how within-host pathogen diversity may regulate the abundance of parasites. PMID:26767166

  10. 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.

  11. Case series of naturally acquired Plasmodium knowlesi infection in a tertiary teaching hospital.

    PubMed

    Azira, N M S; Zairi, N Z; Amry, A R; Zeehaida, M

    2012-09-01

    Plasmodium knowlesi is a simian malaria parasite and is recently recognized as the fifth malaria parasite infecting humans. Manifestation of the infection may resemble other infection particularly dengue fever leading to inappropriate management and delay in treatment. We reported three cases of naturally acquired P. knowlesi in Hospital Universiti Sains Malaysia, Kubang Kerian, Kelantan, Malaysia. Clinical manifestations were quite similar in those cases. Microscopically, the diagnosis might be challenging. These cases were confirmed by polymerase chain reaction method which serves as a gold standard. PMID:23018503

  12. Lactate dehydrogenase as a marker of Plasmodium infection in malaria vector Anopheles.

    PubMed

    Riandey, M F; Sannier, C; Peltre, G; Monteny, N; Cavaleyra, M

    1996-06-01

    Lactate dehydrogenase (Ldh) electrophoresis showed the presence of Plasmodium yoelii yoelii in Anopheles stephensi and An. gambiae. The Ldh appeared as an additional band (pLdh) whose activity was more intense with 3-acetyl pyridine adenine dinucleotide as coenzyme than with beta nicotin-amide adenine dinucleotide. Several allelic forms occurred both in the vector and the host. The isoelectric point of Ldh, similar in the vector and host, differed from those of Ldh from mosquito and mouse. The presence of pLdh was detected from the 2nd to the 28th day of infection. The pLdh appeared to be proportional to the number of sporozoites present in infected salivary glands. However, pLdh was not found in salivary glands or midguts, but it was detected in the rest of the corresponding mosquito. The origin and use of pLdh as a marker of Plasmodium in its vector is discussed. PMID:8827592

  13. A Nature-Inspired Betalainic Probe for Live-Cell Imaging of Plasmodium-Infected Erythrocytes

    PubMed Central

    Gonçalves, Letícia Christina Pires; Tonelli, Renata Rosito; Bagnaresi, Piero; Mortara, Renato Arruda; Ferreira, Antonio Gilberto; Bastos, Erick Leite

    2013-01-01

    A model betalainic dye was semisynthesized from betanin, the magenta pigment of the red beet, and was effective for live-cell imaging of Plasmodium-infected red blood cells. This water-soluble fluorescent probe is photostable, excitable in the visible region and cell membrane-permeable, and its photophysical properties are not notably pH-sensitive. Fluorescence imaging microscopy of erythrocytes infected with Plasmodium falciparum, a causative agent of malaria in humans, showed that only the parasite was stained. Z-stacking analysis suggested that the probe accumulates proximal to the nucleus of the parasite. Indicaxanthin, one of the natural fluorescent betalains found in the petals of certain flowers, did not stain the parasite or the red blood cell. PMID:23342028

  14. A nature-inspired betalainic probe for live-cell imaging of Plasmodium-infected erythrocytes.

    PubMed

    Gonçalves, Letícia Christina Pires; Tonelli, Renata Rosito; Bagnaresi, Piero; Mortara, Renato Arruda; Ferreira, Antonio Gilberto; Bastos, Erick Leite

    2013-01-01

    A model betalainic dye was semisynthesized from betanin, the magenta pigment of the red beet, and was effective for live-cell imaging of Plasmodium-infected red blood cells. This water-soluble fluorescent probe is photostable, excitable in the visible region and cell membrane-permeable, and its photophysical properties are not notably pH-sensitive. Fluorescence imaging microscopy of erythrocytes infected with Plasmodium falciparum, a causative agent of malaria in humans, showed that only the parasite was stained. Z-stacking analysis suggested that the probe accumulates proximal to the nucleus of the parasite. Indicaxanthin, one of the natural fluorescent betalains found in the petals of certain flowers, did not stain the parasite or the red blood cell. PMID:23342028

  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. PMID:17160261

  16. Modeling the Dynamics of Plasmodium vivax Infection and Hypnozoite Reactivation In Vivo

    PubMed Central

    Adekunle, Adeshina I.; Pinkevych, Mykola; McGready, Rose; Luxemburger, Christine; White, Lisa J.; Nosten, François; Cromer, Deborah; Davenport, Miles P.

    2015-01-01

    The dynamics of Plasmodium vivax infection is characterized by reactivation of hypnozoites at varying time intervals. The relative contribution of new P. vivax infection and reactivation of dormant liver stage hypnozoites to initiation of blood stage infection is unclear. In this study, we investigate the contribution of new inoculations of P. vivax sporozoites to primary infection versus reactivation of hypnozoites by modeling the dynamics of P. vivax infection in Thailand in patients receiving treatment for either blood stage infection alone (chloroquine), or the blood and liver stages of infection (chloroquine + primaquine). In addition, we also analysed rates of infection in a study in Papua New Guinea (PNG) where patients were treated with either artesunate, or artesunate + primaquine. Our results show that up to 96% of the P. vivax infection is due to hypnozoite reactivation in individuals living in endemic areas in Thailand. Similar analysis revealed the around 70% of infections in the PNG cohort were due to hypnozoite reactivation. We show how the age of the cohort, primaquine drug failure, and seasonality may affect estimates of the ratio of primary P. vivax infection to hypnozoite reactivation. Modeling of P. vivax primary infection and hypnozoite reactivation provides important insights into infection dynamics, and suggests that 90–96% of blood stage infections arise from hypnozoite reactivation. Major differences in infection kinetics between Thailand and PNG suggest the likelihood of drug failure in PNG. PMID:25780913

  17. A Novel Model of Asymptomatic Plasmodium Parasitemia That Recapitulates Elements of the Human Immune Response to Chronic Infection.

    PubMed

    Fontana, Mary F; Baccarella, Alyssa; Craft, Joshua F; Boyle, Michelle J; McIntyre, Tara I; Wood, Matthew D; Thorn, Kurt S; Anidi, Chioma; Bayat, Aqieda; Chung, Me Ree; Hamburger, Rebecca; Kim, Chris Y; Pearman, Emily; Pham, Jennifer; Tang, Jia J; Boon, Louis; Kamya, Moses R; Dorsey, Grant; Feeney, Margaret E; Kim, Charles C

    2016-01-01

    In humans, immunity to Plasmodium sp. generally takes the form of protection from symptomatic malaria (i.e., 'clinical immunity') rather than infection ('sterilizing immunity'). In contrast, mice infected with Plasmodium develop sterilizing immunity, hindering progress in understanding the mechanistic basis of clinical immunity. Here we present a novel model in which mice persistently infected with P. chabaudi exhibit limited clinical symptoms despite sustaining patent parasite burdens for many months. Characterization of immune responses in persistently infected mice revealed development of CD4+ T cell exhaustion, increased production of IL-10, and expansion of B cells with an atypical surface phenotype. Additionally, persistently infected mice displayed a dramatic increase in circulating nonclassical monocytes, a phenomenon that we also observed in humans with both chronic Plasmodium exposure and asymptomatic infection. Following pharmacological clearance of infection, previously persistently infected mice could not control a secondary challenge, indicating that persistent infection disrupts the sterilizing immunity that typically develops in mouse models of acute infection. This study establishes an animal model of asymptomatic, persistent Plasmodium infection that recapitulates several central aspects of the immune response in chronically exposed humans. As such, it provides a novel tool for dissection of immune responses that may prevent development of sterilizing immunity and limit pathology during infection. PMID:27583554

  18. Effects of chronic avian malaria (Plasmodium relictum) infection on reproductive success of Hawaii Amakihi (Hemignathus virens)

    USGS Publications Warehouse

    Kilpatrick, A.M.; Lapointe, D.A.; Atkinson, C.T.; Woodworth, B.L.; Lease, J.K.; Reiter, M.E.; Gross, K.

    2006-01-01

    We studied the effects of chronic avian malaria (Plasmodium relictum) infections on the reproductive success of a native Hawaiian honeycreeper, Hawaii Amakihi (Hemignathus virens). Chronic malaria infections in male and female parents did not significantly reduce reproductive success as measured by clutch size, hatching success, fledging mass, number of nestlings fledged, nesting success (daily survival rate), and minimum fledgling survival. In fact, nesting success of pairs with chronically infected males was significantly higher than those with uninfected males (76% vs. 38%), and offspring that had at least one parent that had survived the acute phase of malaria infection had a significantly greater chance of being resighted the following year (25% vs. 10%). The reproduction and survival of infected birds were sufficient for a per-capita population growth rate >1, which suggests that chronically infected Hawaii Amakihi could support a growing population. ?? The American Ornithologists' Union, 2006.

  19. Development of sporogonic cycle of Plasmodium vivax in experimentally infected Anopheles albimanus mosquitoes.

    PubMed

    Salas, M L; Romero, J F; Solarte, Y; Olano, V; Herrera, M A; Herrera, S

    1994-01-01

    The sporogonic cycle of Plasmodium vivax was established and maintained under laboratory conditions in two different strains of Anopheles albimanus mosquitoes using as a parasite source blood from human patients or from Aotus monkeys infected with the VCC-2 P.vivax colombian isolate. Both the Tecojate strain isolate from Guatemala and the Cartagena strain from the colombian Pacific coast were susceptible to infections with P.vivax. A higher percentage of Cartagena mosquitoes was infected per trial, however the Tecojate strain developed higher sporozoite loads. Intravenous inoculation of Aotus monkeys with sporozoites obtained from both anopheline strains resulted in successful blood infections. Animals infected with sporozoites from the Tecojate strain presented a patent period of 21-32 days whereas parasitemia appeared between days 19-53 in monkeys infected with sporozites from Cartagena strain. PMID:7565121

  20. 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

  1. Resistance to Therapies for Infection by Plasmodium vivax

    PubMed Central

    Baird, J. Kevin

    2009-01-01

    The gravity of the threat posed by vivax malaria to public health has been poorly appreciated. The widely held misperception of Plasmodium vivax as being relatively infrequent, benign, and easily treated explains its nearly complete neglect across the range of biological and clinical research. Recent evidence suggests a far higher and more-severe disease burden imposed by increasingly drug-resistant parasites. The two frontline therapies against vivax malaria, chloroquine and primaquine, may be failing. Despite 60 years of nearly continuous use of these drugs, their respective mechanisms of activity, resistance, and toxicity remain unknown. Although standardized means of assessing therapeutic efficacy against blood and liver stages have not been developed, this review examines the provisional in vivo, ex vivo, and animal model systems for doing so. The rationale, design, and interpretation of clinical trials of therapies for vivax malaria are discussed in the context of the nuance and ambiguity imposed by the hypnozoite. Fielding new drug therapies against real-world vivax malaria may require a reworking of the strategic framework of drug development, namely, the conception, testing, and evaluation of sets of drugs designed for the cure of both blood and liver asexual stages as well as the sexual blood stages within a single therapeutic regimen. PMID:19597012

  2. Molecular Aspects of Plasmodium falciparum Infection during Pregnancy

    PubMed Central

    Ndam, Nicaise Tuikue; Deloron, Philippe

    2007-01-01

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

  3. Evaluation of Artemisone Combinations in Aotus Monkeys Infected with Plasmodium falciparum▿

    PubMed Central

    Obaldia, Nicanor; Kotecka, Barbara M.; Edstein, Michael D.; Haynes, Richard K.; Fugmann, Burkhard; Kyle, Dennis E.; Rieckmann, Karl H.

    2009-01-01

    Artemisone (single oral dose, 10 mg/kg of body weight) cured nonimmune Aotus monkeys of their Plasmodium falciparum infections when combined with mefloquine (single oral dose, 5 and 10 mg/kg but not 2.5 mg/kg). In combination with amodiaquine (20 mg/kg/day), artemisone (10 mg/kg/day) given orally for 3 days cured all infected monkeys. Three days of treatment with artemisone (30 mg/kg/day) and clindamycin (100 mg/kg/day) was also curative. PMID:19506062

  4. Evaluation of artemisone combinations in Aotus monkeys infected with Plasmodium falciparum.

    PubMed

    Obaldia, Nicanor; Kotecka, Barbara M; Edstein, Michael D; Haynes, Richard K; Fugmann, Burkhard; Kyle, Dennis E; Rieckmann, Karl H

    2009-08-01

    Artemisone (single oral dose, 10 mg/kg of body weight) cured nonimmune Aotus monkeys of their Plasmodium falciparum infections when combined with mefloquine (single oral dose, 5 and 10 mg/kg but not 2.5 mg/kg). In combination with amodiaquine (20 mg/kg/day), artemisone (10 mg/kg/day) given orally for 3 days cured all infected monkeys. Three days of treatment with artemisone (30 mg/kg/day) and clindamycin (100 mg/kg/day) was also curative. PMID:19506062

  5. Extraction of Hydrophilic Metabolites from Plasmodium falciparum-Infected Erythrocytes for Metabolomic Analysis

    PubMed Central

    Olszewski, Kellen L.; Llinás, Manuel

    2012-01-01

    Metabolomics is an increasingly common analytical approach for investigating metabolic networks of pathogenic organisms. This may be of particular use in the study of parasitic infections due to the intrinsic metabolic connection between the parasite and its host. In vitro cultures of the malaria parasite Plasmodium falciparum present a valuable platform to elucidate the structure and dynamics of the parasite’s metabolic network and to determine the mechanisms of action of antimalarial drugs and drug resistance mutations. Accurately measuring metabolite levels requires a reproducible method for quantifying intracellular metabolites. Here we present a simple protocol for extracting hydrophilic metabolites from P. falciparum-infected erythrocyte cultures. PMID:22990783

  6. Acute pancreatitis, ascites, and acute renal failure in Plasmodium vivax malaria infection, a rare complication.

    PubMed

    Lakhotia, Manoj; Pahadiya, Hans Raj; Kumar, Harish; Singh, Jagdish; Sangappa, Jainapur Ravi; Choudhary, Prakash Kumar

    2015-01-01

    A 22-year-old male presented with 6 days history of intermittent fever with chills, 2 days history of upper abdomen pain, distension of abdomen, and decreased urine output. He was diagnosed to have Plasmodium vivax malaria, acute pancreatitis, ascites, and acute renal failure. These constellations of complications in P. vivax infection have never been reported in the past. The patient responded to intravenous chloroquine and supportive treatment. For renal failure, he required hemodialysis. Acute pancreatitis, ascites, and acute renal failure form an unusual combination in P. vivax infection. PMID:26629455

  7. High Prevalence of Plasmodium falciparum Infection in Asymptomatic Individuals from the Democratic Republic of the Congo

    PubMed Central

    Mvumbi, Dieudonné Makaba; Bobanga, Thierry Lengu; Melin, Pierrette; De Mol, Patrick; Kayembe, Jean-Marie Ntumba; Situakibanza, Hippolyte Nani-Tuma; Mvumbi, Georges Lelo; Nsibu, Célestin Ndosimao; Umesumbu, Solange Efundu; Hayette, Marie-Pierre

    2016-01-01

    Malaria remains a major public health problem in the Democratic Republic of Congo (DRC) with 14 million cases reported by the WHO Malaria Report in 2014. Asymptomatic malaria cases are known to be prevalent in endemic areas and are generally untreated, resulting in a significant source of gametocytes that may serve as reservoir of disease transmission. Considering that microscopy certainly underestimates the prevalence of Plasmodium infections within asymptomatic carriers and that PCR assays are currently recognized as the most sensitive methods for Plasmodium identification, this study was conducted to weigh the asymptomatic carriage in DRC by a molecular method. Six provinces were randomly selected for blood collection in which 80 to 100 individuals were included in the study. Five hundred and eighty blood samples were collected and molecular diagnosis was performed. Globally, almost half of the samples collected from asymptomatic individuals (280/580; 48.2%) had Plasmodium infections and the most species identified was P. falciparum alone in combination with P. malariae. The high prevalence reported here should interpellate the bodies involved in malaria control in DR Congo to take into account asymptomatic carriers in actions taken and consider asymptomatic malaria as a major hurdle for malaria elimination. PMID:26942036

  8. Labelling of membrane glycoprotein in erythrocytes infected with Plasmodium knowlesi*

    PubMed Central

    Trigg, P. I.; Hirst, S. I.; Shakespeare, P. G.; Tappenden, L.

    1977-01-01

    Normal rhesus monkey erythrocytes and erythrocytes infected by P. knowlesi were labelled with galactose oxidase (EC 1.1.3.9) and tritiated sodium borohydride. The glycoproteins of normal erythrocytes were not labelled unless the cells were pretreated with neuraminidase, when peaks of activity with apparent molecular weights of 170 000, 126 000, 90 000, 50 000, and 35 000 were observed. Schizont-infected erythrocytes showed an absence of glycoprotein labelling even after neuraminidase treatment. The results indicate that there is an alteration in the glycoproteins of schizont-infected erythrocytes, which may contribute to the increased permeability and the immunological alterations on the surface of these cells. PMID:412601

  9. Epidemiology and Infectivity of Plasmodium falciparum and Plasmodium vivax Gametocytes in Relation to Malaria Control and Elimination

    PubMed Central

    Bousema, Teun; Drakeley, Chris

    2011-01-01

    Summary: Malaria remains a major cause of morbidity and mortality in the tropics, with Plasmodium falciparum responsible for the majority of the disease burden and P. vivax being the geographically most widely distributed cause of malaria. Gametocytes are the sexual-stage parasites that infect Anopheles mosquitoes and mediate the onward transmission of the disease. Gametocytes are poorly studied despite this crucial role, but with a recent resurgence of interest in malaria elimination, the study of gametocytes is in vogue. This review highlights the current state of knowledge with regard to the development and longevity of P. falciparum and P. vivax gametocytes in the human host and the factors influencing their distribution within endemic populations. The evidence for immune responses, antimalarial drugs, and drug resistance influencing infectiousness to mosquitoes is reviewed. We discuss how the application of molecular techniques has led to the identification of submicroscopic gametocyte carriage and to a reassessment of the human infectious reservoir. These components are drawn together to show how control measures that aim to reduce malaria transmission, such as mass drug administration and a transmission-blocking vaccine, might better be deployed. PMID:21482730

  10. An epidemiologically successful Escherichia coli sequence type modulates Plasmodium falciparum infection in the mosquito midgut.

    PubMed

    Tchioffo, Majoline T; Abate, Luc; Boissière, Anne; Nsango, Sandrine E; Gimonneau, Geoffrey; Berry, Antoine; Oswald, Eric; Dubois, Damien; Morlais, Isabelle

    2016-09-01

    Malaria transmission relies on the successful development of Plasmodium parasites in the Anopheles mosquito vector. Within the mosquito midgut, malaria parasites encounter a resident bacterial flora and parasite-bacteria interactions modulate Plasmodium development. The mechanisms by which the bacteria interact with malaria parasites are still unknown. The intestinal microbiota could regulate immune signaling pathways or produce bacterial compounds that block Plasmodium development. In this study, we characterized Escherichia coli strains previously isolated from the Anopheles mosquito midgut and investigated the putative role of two E. coli clones, 444ST95 and 351ST73, on parasite development. Sporogonic development was significantly impacted by exposure to clone 444ST95 whereas prevalence and intensity of infection were not different in mosquitoes challenged with 351ST73 as compared to control mosquitoes. This result indicates midgut bacteria exhibit intra-specific variation in their ability to inhibit Plasmodium development. Expression patterns of immune genes differed between mosquitoes challenged with 444ST95 and 351ST73 and examination of the luminal midgut surface by transmission electron microscopy revealed distinct effects of bacterial exposure on midgut epithelial cells. The 444ST95 clone strongly affected mosquito survival and parasite development and this could be associated to the Hemolysin F or other toxins released by the bacteria. Further studies will be needed to decipher the virulence factors and to determine their contribution to the observed phenotype of the 444ST95E. coli strain that belongs to the epidemiological ST95 clonal group responsible for extra intestinal infections in human and other animals. PMID:27154329

  11. Leishmania donovani infection drives the priming of human monocyte-derived dendritic cells during Plasmodium falciparum co-infections.

    PubMed

    van den Bogaart, E; de Bes, H M; Balraadjsing, P P S; Mens, P F; Adams, E R; Grobusch, M P; van Die, I; Schallig, H D F H

    2015-09-01

    Functional impairment of dendritic cells (DCs) is part of a survival strategy evolved by Leishmania and Plasmodium parasites to evade host immune responses. Here, the effects of co-exposing human monocyte-derived DCs to Leishmania donovani promastigotes and Plasmodium falciparum-infected erythrocytes were investigated. Co-stimulation resulted in a dual, dose-dependent effect on DC differentiation which ranged from semi-mature cells, secreting low interleukin(-12p70 levels to a complete lack of phenotypic maturation in the presence of high parasite amounts. The effect was mainly triggered by the Leishmania parasites, as illustrated by their ability to induce semi-mature, interleukin-10-producing DCs, that poorly responded to lipopolysaccharide stimulation. Conversely, P. falciparum blood-stage forms failed to activate DCs and only slightly interfered with lipopolysaccharide effects. Stimulation with high L. donovani concentrations triggered phosphatidylserine translocation, whose onset presented after initiating the maturation impairment process. When added in combination, the two parasites could co-localize in the same DCs, confirming that the leading effects of Leishmania over Plasmodium may not be due to mutual exclusion. Altogether, these results suggest that in the presence of visceral leishmaniasis-malaria co-infections, Leishmania-driven effects may overrule the more silent response elicited by P. falciparum, shaping host immunity towards a regulatory pattern and possibly delaying disease resolution. PMID:26173941

  12. Studying fitness cost of Plasmodium falciparum infection in malaria vectors: validation of an appropriate negative control

    PubMed Central

    2013-01-01

    Background The question whether Plasmodium falciparum infection affects the fitness of mosquito vectors remains open. A hurdle for resolving this question is the lack of appropriate control, non-infected mosquitoes that can be compared to the infected ones. It was shown recently that heating P. falciparum gametocyte-infected blood before feeding by malaria vectors inhibits the infection. Therefore, the same source of gametocyte-infected blood could be divided in two parts, one heated, serving as the control, the other unheated, allowing the comparison of infected and uninfected mosquitoes which fed on exactly the same blood otherwise. However, before using this method for characterizing the cost of infection to mosquitoes, it is necessary to establish whether feeding on previously heated blood affects the survival and fecundity of mosquito females. Methods Anopheles gambiae M molecular form females were exposed to heated versus non-heated, parasite-free human blood to mimic blood meal on non-infectious versus infectious gametocyte-containing blood. Life history traits of mosquito females fed on blood that was heat-treated or not were then compared. Results The results reveal that heat treatment of the blood did not affect the survival and fecundity of mosquito females. Consistently, blood heat treatment did not affect the quantity of blood ingested. Conclusions The study indicates that heat inactivation of gametocyte-infected blood will only inhibit mosquito infection and that this method is suitable for quantifying the fitness cost incurred by mosquitoes upon infection by P. falciparum. PMID:23282172

  13. Evaluation of three rapid diagnostic tests for the detection of human infections with Plasmodium knowlesi

    PubMed Central

    2014-01-01

    Background Plasmodium knowlesi, a malaria parasite of Southeast Asian macaques, infects humans and can cause fatal malaria. It is difficult to diagnose by microscopy because of morphological similarity to Plasmodium malariae. Nested PCR assay is the most accurate method to distinguish P. knowlesi from other Plasmodium species but is not cost effective in resource-poor settings. Rapid diagnostic tests (RDTs) are recommended for settings where malaria is prevalent. In this study, the effectiveness of three RDTs in detecting P. knowlesi from fresh and frozen patient blood samples was evaluated. Methods Forty malaria patients (28 P. knowlesi, ten P. vivax and two P. falciparum) diagnosed by microscopy were recruited in Sarawak, Malaysian Borneo during a 16-month period. Patient blood samples were used to determine parasitaemia by microscopy, confirm the Plasmodium species present by PCR and evaluate three RDTs: OptiMAL-IT, BinaxNOW® Malaria and Paramax-3. The RDTs were also evaluated using frozen blood samples from 41 knowlesi malaria patients. Results OptiMAL-IT was the most sensitive RDT, with a sensitivity of 71% (20/28; 95% CI = 54-88%) for fresh and 73% (30/41; 95% CI = 59-87%) for frozen knowlesi samples. However, it yielded predominantly falciparum-positive results due to cross-reactivity of the P. falciparum test reagent with P. knowlesi. BinaxNOW® Malaria correctly detected non-P. falciparum malaria in P. knowlesi samples but was the least sensitive, detecting only 29% (8/28; 95% CI = 12-46%) of fresh and 24% (10/41; 95% CI = 11-37%) of frozen samples. The Paramax-3 RDT tested positive for P. vivax with PCR-confirmed P. knowlesi samples with sensitivities of 40% (10/25; 95% CI = 21-59%) with fresh and 32% (13/41; 95% CI = 17-46%) with frozen samples. All RDTs correctly identified P. falciparum- and P. vivax-positive controls with parasitaemias above 2,000 parasites/μl blood. Conclusions The RDTs detected Plasmodium in P. knowlesi-infected blood samples with

  14. Plasmodium berghei and Plasmodium chabaudi: a neutral endopeptidase in parasite extracts and plasma of infected animals.

    PubMed

    Bernard, F; Mayer, R; Picard, I; Deguercy, A; Monsigny, M; Schrevel, J

    1987-08-01

    By using a sensitive fluorometric method with Val-Leu-Gly-Arg-3-amino-9-ethylcarbazole (VLGR-AEC) as a substrate, two endopeptidase activities were identified in two fractions of Sephacryl S-200 gel filtration from soluble P. berghei and P. chabaudi extracts. Controls with normal mouse erythrocytes, with leukocytes, and with reticulocyte enriched blood and different washing procedures during the preparation of soluble P. berghei extracts showed that the MW greater than 200 kDa fraction was a contaminant from erythrocytes and exhibited an optimal pH activity of 8.2. In contrast, the fraction 130 kDa was related to P. berghei and P. chabaudi and exhibited an optimal pH activity of 7.4. The two enzyme activities were compared with eight different substrates. The parasite endopeptidase showed a strong activity with Val-Leu-Gly-Lys-AEC (VLGK-AEC) and Ser-Gly-Lys-AEC (SGK-AEC) as substrates; in contrast, the mouse host endopeptidase poorly cleaved the VLGK-AEC and did not cleave SGK-AEC. Presence of the hydrophobic benzyl group on serine reduced the hydrolizing properties of P. berghei endopeptidase: the reverse was observed with host endopeptidase. The hydrolysis of the N-polyhydroxyalcanoyl-VLGK-AEC substrate by the parasite neutral endopeptidase strongly increased with the schizogonic stage, as shown with synchronized P. chabaudi in mice. By its physiological pH and specificity the release of this enzyme in mouse plasma during the infection could be of interest in a peptidyl-drug strategy. PMID:3301390

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

    PubMed Central

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

    2016-01-01

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

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

    PubMed

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

    2016-04-01

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

  17. Wolbachia infections in natural Anopheles populations affect egg laying and negatively correlate with Plasmodium development.

    PubMed

    Shaw, W Robert; Marcenac, Perrine; Childs, Lauren M; Buckee, Caroline O; Baldini, Francesco; Sawadogo, Simon P; Dabiré, Roch K; Diabaté, Abdoulaye; Catteruccia, Flaminia

    2016-01-01

    The maternally inherited alpha-proteobacterium Wolbachia has been proposed as a tool to block transmission of devastating mosquito-borne infectious diseases like dengue and malaria. Here we study the reproductive manipulations induced by a recently identified Wolbachia strain that stably infects natural mosquito populations of a major malaria vector, Anopheles coluzzii, in Burkina Faso. We determine that these infections significantly accelerate egg laying but do not induce cytoplasmic incompatibility or sex-ratio distortion, two parasitic reproductive phenotypes that facilitate the spread of other Wolbachia strains within insect hosts. Analysis of 221 blood-fed A. coluzzii females collected from houses shows a negative correlation between the presence of Plasmodium parasites and Wolbachia infection. A mathematical model incorporating these results predicts that infection with these endosymbionts may reduce malaria prevalence in human populations. These data suggest that Wolbachia may be an important player in malaria transmission dynamics in Sub-Saharan Africa. PMID:27243367

  18. Wolbachia infections in natural Anopheles populations affect egg laying and negatively correlate with Plasmodium development

    PubMed Central

    Shaw, W. Robert; Marcenac, Perrine; Childs, Lauren M.; Buckee, Caroline O.; Baldini, Francesco; Sawadogo, Simon P.; Dabiré, Roch K.; Diabaté, Abdoulaye; Catteruccia, Flaminia

    2016-01-01

    The maternally inherited alpha-proteobacterium Wolbachia has been proposed as a tool to block transmission of devastating mosquito-borne infectious diseases like dengue and malaria. Here we study the reproductive manipulations induced by a recently identified Wolbachia strain that stably infects natural mosquito populations of a major malaria vector, Anopheles coluzzii, in Burkina Faso. We determine that these infections significantly accelerate egg laying but do not induce cytoplasmic incompatibility or sex-ratio distortion, two parasitic reproductive phenotypes that facilitate the spread of other Wolbachia strains within insect hosts. Analysis of 221 blood-fed A. coluzzii females collected from houses shows a negative correlation between the presence of Plasmodium parasites and Wolbachia infection. A mathematical model incorporating these results predicts that infection with these endosymbionts may reduce malaria prevalence in human populations. These data suggest that Wolbachia may be an important player in malaria transmission dynamics in Sub-Saharan Africa. PMID:27243367

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

    PubMed

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

    2016-07-01

    Plasmodium falciparum exports a large number of proteins to its host cell, the mature human erythrocyte, where they are involved in host cell modification. Amongst the proteins trafficked to the host cell, many are heat shock protein (HSP)40 homologues. We previously demonstrated that at least two exported PfHSP40s (referred to as PFE55 and PFA660) localise to mobile structures in the P. falciparum-infected erythrocyte (Kulzer et al., 2010), termed J-dots. The complete molecular content of these structures has not yet been completely resolved, however it is known that they also contain an exported HSP70, PfHSP70x, and are potentially involved in transport of the major cytoadherance ligand, PfEMP1, through the host cell. To understand more about the nature of the association of exported HSP40s with J-dots, here we have studied the signal requirements for recruitment of the proteins to these structures. By expressing various exported GFP chimeras, we can demonstrate that the predicted substrate binding domain is necessary and sufficient for J-dot targeting. This targeting only occurs in human erythrocytes infected with P. falciparum, as it is not conserved when expressing a P. falciparum HSP40 in Plasmodium berghei-infected murine red blood cells, suggesting that J-dots are P. falciparum-specific. This data reveals a new mechanism for targeting of exported proteins to intracellular structures in the P. falciparum-infected erythrocyte. PMID:27063072

  20. Antiplasmodial Effect of Anthocleista vogelii on Albino Mice Experimentally Infected with Plasmodium berghei berghei (NK 65)

    PubMed Central

    Gboeloh, Lebari Barine; Okon, Okpok Eta; Udoh, Samuel Effiong

    2014-01-01

    The objective of the present study was to investigate the antiplasmodial effect of the ethanolic stem bark extract of Anthocleista vogelii at different doses in albino mice infected with Plasmodium berghei berghei (NK 65). Thirty-six mice were divided into six groups of six mice each. Five groups (B1–B3, D, and G) were infected with Plasmodium berghei berghei parasitized red blood cells. Groups D, H, and G served as the controls. Six days after infection, mice in groups B1, B2, and B3 were treated orally with 100, 200, and 400 mg/kg body weight of Anthocleista vogelii, respectively, for six executive days. Group D was treated with 5 mg/kg body weight of chloroquine while Group G was given distilled water. Group H was not infected and was not treated. It served as the normal control. The extracts exhibited significant (P < 0.05) dose-dependent chemosuppression of P. berghei. The extract exhibited average chemosuppressive effects of 48.5%, 78.5%, and 86.6% at dose levels of 100, 200, and 400 mg/kg body weight, respectively. Phytochemical screening of the plant extract revealed the presence of saponins, cardiac glycosides, flavonoids, terpenes, alkaloids, and steroid. The acute toxicity (LD50) of the plant was estimated to be 3162 mg/kg body weight. It showed that the stem bark of A. vogelii possesses antiplasmodial property. PMID:24900913

  1. Hepatitis B Virus Infection Does Not Significantly Influence Plasmodium Parasite Density in Asymptomatic Infections in Ghanaian Transfusion Recipients

    PubMed Central

    Freimanis, Graham Lee; Owusu-Ofori, Shirley; Allain, Jean-Pierre

    2012-01-01

    Background Areas endemic for malaria and Hepatitis B virus (HBV) infection largely overlap geographically. A recent study has suggested the existence of an interaction between the two pathogens in symptomatic co-infected individuals on the South-American continent. We examined this issue in a hyperendemic area for both pathogens in sub-Saharan Africa. Methodology and Findings Pre-transfusion samples from a retrospective cohort of 154 blood transfusion recipients were screened for both serological and molecular markers of HBV and Plasmodium genomes using species-specific nested PCR and quantitative real-time PCR. Thirty-seven individuals met exclusion criteria and were subsequently eliminated from further analysis. Of 117 participants, 90% of recipients exhibited evidence of exposure to HBV, 42% with HBsAg and/or HBV DNA and 48% anti-HBc reactive without detectable HBV DNA. Plasmodium genome prevalence by NAT was 50%. Parasitemic individuals were significantly younger than non-parasitemic individuals (P = 0.04). Parasitemia level was not significantly lower in individuals with HBV DNA positive infections compared to those with HBV DNA negative exposures. HBV DNA load was not significantly different in parasitemic and non-parasitemic individuals. Conclusion The data presented suggests that, in sub-Saharan Africa, asymptomatic co-infections with these two ubiquitous pathogens do not appear to significantly affect each other and evolve independently. PMID:23185500

  2. Acute respiratory distress syndrome and acute renal failure from Plasmodium ovale infection with fatal outcome

    PubMed Central

    2013-01-01

    Background Plasmodium ovale is one of the causative agents of human malaria. Plasmodium ovale infection has long been thought to be non-fatal. Due to its lower morbidity, P. ovale receives little attention in malaria research. Methods Two Malaysians went to Nigeria for two weeks. After returning to Malaysia, they fell sick and were admitted to different hospitals. Plasmodium ovale parasites were identified from blood smears of these patients. The species identification was further confirmed with nested PCR. One of them was successfully treated with no incident of relapse within 12-month medical follow-up. The other patient came down with malaria-induced respiratory complication during the course of treatment. Although parasites were cleared off the circulation, the patient’s condition worsened. He succumbed to multiple complications including acute respiratory distress syndrome and acute renal failure. Results Sequencing of the malaria parasite DNA from both cases, followed by multiple sequence alignment and phylogenetic tree construction suggested that the causative agent for both malaria cases was P. ovale curtisi. Discussion In this report, the differences between both cases were discussed, and the potential capability of P. ovale in causing severe complications and death as seen in this case report was highlighted. Conclusion Plasmodium ovale is potentially capable of causing severe complications, if not death. Complete travel and clinical history of malaria patient are vital for successful diagnoses and treatment. Monitoring of respiratory and renal function of malaria patients, regardless of the species of malaria parasites involved is crucial during the course of hospital admission. PMID:24180319

  3. Hepatic profile of Gallus gallus Linnaeus, 1758 experimentally infected by Plasmodium juxtanucleare Versiani & Gomes, 1941.

    PubMed

    Vashist, Usha; Falqueto, Aline Duarte; Lustrino, Danilo; Tunholi, Victor Menezes; Tunholi-Alves, Vinícius Menezes; dos Santos, Marcos Antônio José; D'Agosto, Marta; Massard, Carlos Luiz; Pinheiro, Jairo

    2011-02-10

    One of the species that causes avian malaria is Plasmodium juxtanucleare. It is commonly found in poultry, especially when the birds receive food free of coccidiostats. Since industrial and organic poultry breeding is increasing in the world and few studies have been conducted examining the clinical parameters of both healthy and infected birds, this work evaluated whether the infection caused by P. juxtanucleare in Gallus gallus provokes alterations in the birds' hepatic profile. We analyzed the activity of ALT and AST and carried out histological analyses of liver sections of infected fowls by intracelomic inoculation with infected blood from a donor fowl with a parasite load of around 7%. The infected birds' parasite load was evaluated during 45 days by means of blood smears. There was a positive correlation between the increase in parasite load and higher ALT activity in the infected fowls, but there was no significant variation of the AST activity between the control and infected groups, possibly because of the non-specificity of this enzyme as an indicator of hepatic lesion. The results show that infection caused by P. juxtanucleare in G. gallus provokes hepatic alterations, indicated by the increase in the ALT enzyme activity and by the inflammatory infiltrates found in the liver sections of the infected fowls. PMID:21074323

  4. Malaysian child infected with Plasmodium vivax via blood transfusion: a case report

    PubMed Central

    2013-01-01

    Malaria may be a serious complication of blood transfusion due to the asymptomatic persistence of parasites in some donors. This case report highlights the transfusion-transmitted malaria of Plasmodium vivax in a child diagnosed with germ cell tumour. This child had received blood transfusion from three donors and a week later started developing malaria like symptoms. Nested PCR and sequencing confirmed that one of the three donors was infected with P. vivax and this was transmitted to the 12-year-old child. To the best of the authors’ knowledge, this is the first reported transfusion-transmitted malaria case in Malaysia. PMID:24007496

  5. Plasmodium berghei infection in mice: effect of low-level ozone exposures

    SciTech Connect

    Moore, G.S.; Calabrese, E.J.; Molteni, K.H.

    1984-07-01

    Animal and human studies have accumulated that report erythrocyte effects from inhaled ozone (O/sub 3/). It was the purpose of this research to demonstrate the effects of O/sub 3/ exposure on the course of parasitemia in mice. A study was designed utilizing Plasmodium berghei, a murine malarial parasite host-specific for rodents, as the specific pathogen. The purpose of this project was to study mortality and percent parasitemia in the A/J mouse first infected with P. berghei and then exposed to low levels of ozone.

  6. Individual Plasmodium vivax msp1 Variants within Polyclonal P. vivax Infections Display Different Propensities for Relapse

    PubMed Central

    Juliano, Jonathan J.; Kharabora, Oksana; Sem, Rithy; Lin, Feng-Chang; Muth, Sinuon; Ménard, Didier; Wongsrichanalai, Chansuda; Rogers, William O.; Meshnick, Steven R.

    2012-01-01

    Using a newly developed Plasmodium vivax merozoite surface protein 1 gene (Pvmsp1) heteroduplex tracking assay, we genotyped 107 P. vivax infections in individuals from Cambodia, 45 of whom developed recurrent parasitemia within 42 days. The majority of isolates were polyclonal, but recurrent parasitemias displayed fewer variants compared to initial parasitemias. Two Pvmsp1 gene variants occurred more frequently in the initial genotypes of those who developed recurrent parasitemia, representing the first time P. vivax variants associated with a higher risk of relapse have been described. PMID:22205791

  7. Recruitment of human aquaporin 3 to internal membranes in the Plasmodium falciparum infected erythrocyte.

    PubMed

    Bietz, Sven; Montilla, Irine; Külzer, Simone; Przyborski, Jude M; Lingelbach, Klaus

    2009-09-01

    The molecular mechanisms underlying the formation of the parasitophorous vacuolar membrane in Plasmodium falciparum infected erythrocytes are incompletely understood, and the protein composition of this membrane is still enigmatic. Although the differentiated mammalian erythrocyte lacks the machinery required for endocytosis, some reports have described a localisation of host cell membrane proteins at the parasitophorous vacuolar membrane. Aquaporin 3 is an abundant plasma membrane protein of various cells, including mammalian erythrocytes where it is found in distinct oligomeric states. Here we show that human aquaporin 3 is internalized into infected erythrocytes, presumably during or soon after invasion. It is integrated into the PVM where it is organized in novel oligomeric states which are not found in non-infected cells. PMID:19393693

  8. Distribution and Risk Factors for Plasmodium and Helminth Co-infections: A Cross-Sectional Survey among Children in Bagamoyo District, Coastal Region of Tanzania

    PubMed Central

    Salim, Nahya; Knopp, Stefanie; Lweno, Omar; Abdul, Ummi; Mohamed, Ali; Schindler, Tobias; Rothen, Julian; Masimba, John; Kwaba, Denis; Mohammed, Alisa S.; Althaus, Fabrice; Abdulla, Salim; Tanner, Marcel; Daubenberger, Claudia; Genton, Blaise

    2015-01-01

    Background Plasmodium and soil transmitted helminth infections (STH) are a major public health problem, particularly among children. There are conflicting findings on potential association between these two parasites. This study investigated the Plasmodium and helminth co-infections among children aged 2 months to 9 years living in Bagamoyo district, coastal region of Tanzania. Methods A community-based cross-sectional survey was conducted among 1033 children. Stool, urine and blood samples were examined using a broad set of quality controlled diagnostic methods for common STH (Ascaris lumbricoides, hookworm, Strongyloides stercoralis, Enterobius vermicularis, Trichuris trichura), schistosoma species and Wuchereria bancrofti. Blood slides and malaria rapid diagnostic tests (mRDTs) were utilized for Plasmodium diagnosis. Results Out of 992 children analyzed, the prevalence of Plasmodium infection was 13% (130/992), helminth 28.5% (283/992); 5% (50/992) had co-infection with Plasmodium and helminth. The prevalence rate of Plasmodium, specific STH and co-infections increased significantly with age (p < 0.001), with older children mostly affected except for S. stercoralis monoinfection and co-infections. Spatial variations of co-infection prevalence were observed between and within villages. There was a trend for STH infections to be associated with Plasmodium infection [OR adjusted for age group 1.4, 95% CI (1.0–2.1)], which was more marked for S. stercoralis (OR = 2.2, 95% CI (1.1–4.3). Age and not schooling were risk factors for Plasmodium and STH co-infection. Conclusion The findings suggest that STH and Plasmodium infections tend to occur in the same children, with increasing prevalence of co-infection with age. This calls for an integrated approach such as using mass chemotherapy with dual effect (e.g., ivermectin) coupled with improved housing, sanitation and hygiene for the control of both parasitic infections. PMID:25837022

  9. Anopheles Imd Pathway Factors and Effectors in Infection Intensity-Dependent Anti-Plasmodium Action

    PubMed Central

    Garver, Lindsey S.; Bahia, Ana C.; Das, Suchismita; Souza-Neto, Jayme A.; Shiao, Jessica; Dong, Yuemei; Dimopoulos, George

    2012-01-01

    The Anopheles gambiae immune response against Plasmodium falciparum, an etiological agent of human malaria, has been identified as a source of potential anti-Plasmodium genes and mechanisms to be exploited in efforts to control the malaria transmission cycle. One such mechanism is the Imd pathway, a conserved immune signaling pathway that has potent anti-P. falciparum activity. Silencing the expression of caspar, a negative regulator of the Imd pathway, or over-expressing rel2, an Imd pathway-controlled NFkappaB transcription factor, confers a resistant phenotype on A. gambiae mosquitoes that involves an array of immune effector genes. However, unexplored features of this powerful mechanism that may be essential for the implementation of a malaria control strategy still remain. Using RNA interference to singly or dually silence caspar and other components of the Imd pathway, we have identified genes participating in the anti-Plasmodium signaling module regulated by Caspar, each of which represents a potential target to achieve over-activation of the pathway. We also determined that the Imd pathway is most potent against the parasite's ookinete stage, yet also has reasonable activity against early oocysts and lesser activity against late oocysts. We further demonstrated that caspar silencing alone is sufficient to induce a robust anti-P. falciparum response even in the relative absence of resident gut microbiota. Finally, we established the relevance of the Imd pathway components and regulated effectors TEP1, APL1, and LRIM1 in parasite infection intensity-dependent defense, thereby shedding light on the relevance of laboratory versus natural infection intensity models. Our results highlight the physiological considerations that are integral to a thoughtful implementation of Imd pathway manipulation in A. gambiae as part of an effort to limit the malaria transmission cycle, and they reveal a variety of previously unrecognized nuances in the Imd-directed immune

  10. Impact of sex differences in brain response to infection with Plasmodium berghei.

    PubMed

    Dkhil, Mohamed A; Al-Shaebi, Esam M; Lubbad, Mahmoud Y; Al-Quraishy, Saleh

    2016-01-01

    Malaria is considered to be one of the most prevalent diseases in the world. Severity of the disease between males and females is very important in clinical research areas. In this study, we investigated the impact of sex differences in brain response to infection with Plasmodium berghei. Male and female C57Bl/6 mice were infected with P. berghei-infected erythrocytes. The infection induced a significant change in weight loss in males (-7.2 % ± 0.5) than females (-4.9 % ± 0.6). The maximum parasitemia reached about 15 % at day 9 postinfection. Also, P. berghei infection caused histopathological changes in the brain of mice. These changes were in the form of inflammation, hemorrhage, and structural changes in Purkinje cells. In addition, P. berghei was able to induce a marked oxidative damage in mice brain. The infection induced a significant increase in male brain glutathione than females while the brain catalase level was significantly increased in infected females than infected males. Moreover, the change in brain neurotransmitters, dopamine, epinephrine, norepinephrine, and serotonin, was more in infected males than infected females. At the molecular level, P. berghei was able to induce upregulations of Adam23, Cabp1, Cacnb4, Glrb, and Vdac3-mRNA in the brain of mice. These genes were significantly upregulated in infected males than in infected females. In general, P. berghei could induce structural, biochemical, and molecular alterations in mice brain. Severity of these alterations was different according to sex of mice. PMID:26499384

  11. 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

  12. Monoclonal antibodies produced against sporozoites of the human parasite Plasmodium malariae abolish infectivity of sporozoites of the simian parasite Plasmodium brasilianum.

    PubMed Central

    Cochrane, A H; Barnwell, J W; Collins, W E; Nussenzweig, R S

    1985-01-01

    We have used a sporozoite neutralization assay to define the biological relevance of the cross-reactivity of two monoclonal antibodies, raised against sporozoites of the human parasite Plasmodium malariae (Uganda 1/CDC), with sporozoites of the simian parasite Plasmodium brasilianum (Colombian). In vitro incubation of each of these two monoclonal antibodies with sporozoites of P. brasilianum totally abolished the infectivity of these parasites for Saimiri sciureus. Using Western blot analysis and one of the P. malariae monoclonal antibodies, we identified two sporozoite proteins characteristic of the Colombian isolate of P. brasilianum with apparent molecular weights of 56,000 and 66,000. The same monoclonal antibody identified two proteins in an extract of the Peruvian isolate of P. brasilianum with apparent molecular weights of 59,000 and 69,000. Images PMID:3899939

  13. Host cell remodeling by pathogens: the exomembrane system in Plasmodium-infected erythrocytes

    PubMed Central

    Sherling, Emma S.; van Ooij, Christiaan

    2016-01-01

    Malaria is caused by infection of erythrocytes by parasites of the genus Plasmodium. To survive inside erythrocytes, these parasites induce sweeping changes within the host cell, one of the most dramatic of which is the formation of multiple membranous compartments, collectively referred to as the exomembrane system. As an uninfected mammalian erythrocyte is devoid of internal membranes, the parasite must be the force and the source behind the formation of these compartments. Even though the first evidence of the presence these of internal compartments was obtained over a century ago, their functions remain mostly unclear, and in some cases completely unknown, and the mechanisms underlying their formation are still mysterious. In this review, we provide an overview of the different parts of the exomembrane system, describing the parasitophorous vacuole, the tubovesicular network, Maurer's clefts, the caveola-vesicle complex, J dots and other mobile compartments, and the small vesicles that have been observed in Plasmodium-infected cells. Finally, we combine the data into a simplified view of the exomembrane system and its relation to the alterations of the host erythrocyte. PMID:27587718

  14. Host cell remodeling by pathogens: the exomembrane system in Plasmodium-infected erythrocytes.

    PubMed

    Sherling, Emma S; van Ooij, Christiaan

    2016-09-01

    Malaria is caused by infection of erythrocytes by parasites of the genus Plasmodium To survive inside erythrocytes, these parasites induce sweeping changes within the host cell, one of the most dramatic of which is the formation of multiple membranous compartments, collectively referred to as the exomembrane system. As an uninfected mammalian erythrocyte is devoid of internal membranes, the parasite must be the force and the source behind the formation of these compartments. Even though the first evidence of the presence these of internal compartments was obtained over a century ago, their functions remain mostly unclear, and in some cases completely unknown, and the mechanisms underlying their formation are still mysterious. In this review, we provide an overview of the different parts of the exomembrane system, describing the parasitophorous vacuole, the tubovesicular network, Maurer's clefts, the caveola-vesicle complex, J dots and other mobile compartments, and the small vesicles that have been observed in Plasmodium-infected cells. Finally, we combine the data into a simplified view of the exomembrane system and its relation to the alterations of the host erythrocyte. PMID:27587718

  15. Optimization of a Membrane Feeding Assay for Plasmodium vivax Infection in Anopheles albimanus

    PubMed Central

    Vallejo, Andrés F.; Rubiano, Kelly; Amado, Andres; Krystosik, Amy R.; Herrera, Sócrates; Arévalo-Herrera, Myriam

    2016-01-01

    Introduction Individuals exposed to malaria infections for a long time develop immune responses capable of blocking Plasmodium transmission to mosquito vectors, potentially limiting parasite spreading in nature. Development of a malaria TB vaccine requires a better understanding of the mechanisms and main effectors responsible for transmission blocking (TB) responses. The lack of an in vitro culture system for Plasmodium vivax has been an important drawback for development of a standardized method to assess TB responses to this parasite. This study evaluated host, vector, and parasite factors that may influence Anopheles mosquito infection in order to develop an efficient and reliable assay to assess the TB immunity. Methods/Principal Findings A total of 94 P. vivax infected patients were enrolled as parasite donors or subjects of direct mosquito feeding in two malaria endemic regions of Colombia (Tierralta, and Buenaventura). Parasite infectiousness was assessed by membrane feeding assay or direct feeding assay using laboratory reared Anopheles mosquitoes. Infection was measured by qPCR and by microscopically examining mosquito midguts at day 7 for the presence of oocysts. Best infectivity was attained in four day old mosquitoes fed at a density of 100 mosquitos/cage. Membrane feeding assays produced statistically significant better infections than direct feeding assays in parasite donors; cytokine profiles showed increased IFN-γ, TNF and IL-1 levels in non-infectious individuals. Mosquito infections and parasite maturation were more reliably assessed by PCR compared to microscopy. Conclusions We evaluated mosquito, parasite and host factors that may affect the outcome of parasite transmission as measured by artificial membrane feeding assays. Results have led us to conclude that: 1) optimal mosquito infectivity occurs with mosquitoes four days after emergence at a cage density of 100; 2) mosquito infectivity is best quantified by PCR as it may be underestimated

  16. Modulation of Anopheles stephensi Gene Expression by Nitroquine, an Antimalarial Drug against Plasmodium yoelii Infection in the Mosquito

    PubMed Central

    Zhang, Jian; Zhang, Shuguang; Wang, Yanyan; Xu, Wenyue; Zhang, Jingru; Jiang, Haobo; Huang, Fusheng

    2014-01-01

    Background Antimalarial drugs may impact mosquito’s defense against Plasmodium parasites. Our previous study showed nitroquine significantly reduced infection of Anopheles stephensi by Plasmodium yoelii, but the underlying mechanism remains unclear. In order to understand how transmission capacity of An. stephensi was affected by nitroquine, we explored the transcriptome of adult females after different treatments, examined changes in gene expression profiles, and identified transcripts affected by the drug and parasite. Methodology/Principal Findings We extended massively parallel sequencing and data analysis (including gene discovery, expression profiling, and function prediction) to An. stephensi before and after Plasmodium infection with or without nitroquine treatment. Using numbers of reads assembled into specific contigs to calculate relative abundances (RAs), we categorized the assembled contigs into four groups according to the differences in RA values infection induced, infection suppressed, drug induced, and drug suppressed. We found both nitroquine in the blood meal and Plasmodium infection altered transcription of mosquito genes implicated in diverse processes, including pathogen recognition, signal transduction, prophenoloxidase activation, cytoskeleton assembling, cell adhesion, and oxidative stress. The differential gene expression may have promoted certain defense responses of An. stephensi against the parasite and decreased its infectivity. Conclusions/Significance Our study indicated that nitroquine may regulate several immune mechanisms at the level of gene transcription in the mosquito against Plasmodium infection. This highlights the need for better understanding of antimalarial drug’s impact on parasite survival and transmission. In addition, our data largely enriched the existing sequence information of An. stephensi, an epidemiologically important vector species. PMID:24586804

  17. Hyperparasitaemic human Plasmodium knowlesi infection with atypical morphology in peninsular Malaysia

    PubMed Central

    2013-01-01

    Plasmodium knowlesi is a potentially life-threatening zoonotic malaria parasite due to its relatively short erythrocytic cycle. Microscopic identification of P. knowlesi is difficult, with “compacted parasite cytoplasm” being one of the important identifying keys. This report is about a case of hyperparasitaemic human P. knowlesi infection (27% parasitaemia) with atypical amoeboid morphology. A peninsular Malaysian was admitted to the hospital with malaria. He suffered anaemia and acute kidney function impairment. Microscopic examination, assisted by nested PCR and sequencing confirmed as P. knowlesi infection. With anti-malarial treatment and several medical interventions, patient survived and recovered. One-month medical follow-up was performed after recovery and no recrudescence was noted. This case report highlights the extreme hyperparasitaemic setting, the atypical morphology of P. knowlesi in the patient’s erythrocytes, as well as the medical interventions involved in this successfully treated case. PMID:23496970

  18. The Curative and Prophylactic Effects of Xylopic Acid on Plasmodium berghei Infection in Mice

    PubMed Central

    Boampong, J. N.; Ameyaw, E. O.; Aboagye, B.; Asare, K.; Kyei, S.; Donfack, J. H.; Woode, E.

    2013-01-01

    Efforts have been intensified to search for more effective antimalarial agents because of the observed failure of some artemisinin-based combination therapy (ACT) treatments of malaria in Ghana. Xylopic acid, a pure compound isolated from the fruits of the Xylopia aethiopica, was investigated to establish its attributable prophylactic, curative antimalarial, and antipyretic properties. The antimalarial properties were determined by employing xylopic acid (10–100 mg/kg) in ICR mice infected with Plasmodium berghei. Xylopic acid exerted significant (P < 0.05) effects on P. berghei infection similar to artemether/lumefantrine, the standard drug. Furthermore, it significantly (P < 0.05) reduced the lipopolysaccharide- (LPS-) induced fever in Sprague-Dawley rats similar to prednisolone. Xylopic acid therefore possesses prophylactic and curative antimalarial as well as antipyretic properties which makes it an ideal antimalarial agent. PMID:23970953

  19. Effects of transmission-blocking immunity on Plasmodium vivax infections in Anopheles albimanus populations.

    PubMed

    Ramsey, J M; Salinas, E; Rodriguez, M H; Beaudoin, R L

    1994-02-01

    Two colonized populations of Anopheles albimanus isolated from the Suchiate region, Chiapas State, Mexico, were compared for their susceptibility to coindigenous Plasmodium vivax. Groups of mosquitoes were fed in vitro with either autologous donor blood or the same blood cells substituted with serum negative for anti-gametocyte antibody. Significant differences in susceptibility between the 2 colonies were encountered if the autologous blood from a patient was fed to mosquitoes: mean infection rates of AnA2-positive groups was double that in AnA1 mosquitoes. Consistent for both colonies, only 23.6% of samples positive from malaria-negative serum-substituted blood were infected with an autologous blood feed. Vector competence in these mosquito populations was partially linked to the human populations's immune response to the parasite. PMID:8308663

  20. An 11-year-old boy with Plasmodium falciparum malaria and dengue co-infection.

    PubMed

    Issaranggoon na ayuthaya, Satja; Wangjirapan, Anchalee; Oberdorfer, Peninnah

    2014-01-01

    Malaria and dengue fever are major mosquito-borne public health problems in tropical countries. The authors report a malaria and dengue co-infection in an 11-year-old boy who presented with sustained fever for 10 days. The physical examination revealed a flushed face, injected conjunctivae and left submandibular lymphadenopathy. His peripheral blood smear showed few ring-form trophozoites of Plasmodium falciparum. His blood tests were positive for dengue NS-1 antigen and IgM antibody, and negative for IgG antibody. After the initiation of antimalarial treatment with artesunate and mefloquine, his clinical condition gradually improved. However, he still had low-grade fever that persisted for 6 days. Finally, he recovered well without fluid leakage, shock or severe bleeding. This case report emphasises that early recognition and concomitant treatment of malaria and dengue co-infection in endemic areas can improve clinical outcome and prevent serious complications. PMID:24692379

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

    NASA Astrophysics Data System (ADS)

    Edward, Kert; Farahi, Faramarz

    2014-05-01

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

  2. Consistent Safety and Infectivity in Sporozoite Challenge Model of Plasmodium vivax in Malaria-Naive Human Volunteers

    PubMed Central

    Herrera, Sócrates; Solarte, Yezid; Jordán-Villegas, Alejandro; Echavarría, Juan Fernando; Rocha, Leonardo; Palacios, Ricardo; Ramírez, Óscar; Vélez, Juan D.; Epstein, Judith E.; Richie, Thomas L.; Arévalo-Herrera, Myriam

    2011-01-01

    A safe and reproducible Plasmodium vivax infectious challenge method is required to evaluate the efficacy of malaria vaccine candidates. Seventeen healthy Duffy (+) and five Duffy (−) subjects were randomly allocated into three (A–C) groups and were exposed to the bites of 2–4 Anopheles albimanus mosquitoes infected with Plasmodium vivax derived from three donors. Duffy (−) subjects were included as controls for each group. Clinical manifestations of malaria and parasitemia were monitored beginning 7 days post-challenge. All Duffy (+) volunteers developed patent malaria infection within 16 days after challenge. Prepatent period determined by thick smear, was longer for Group A (median 14.5 d) than for Groups B and C (median 10 d/each). Infected volunteers recovered rapidly after treatment with no serious adverse events. The bite of as low as two P. vivax-infected mosquitoes provides safe and reliable infections in malaria-naive volunteers, suitable for assessing antimalarial and vaccine efficacy trials. PMID:21292872

  3. Consistent safety and infectivity in sporozoite challenge model of Plasmodium vivax in malaria-naive human volunteers.

    PubMed

    Herrera, Sócrates; Solarte, Yezid; Jordán-Villegas, Alejandro; Echavarría, Juan Fernando; Rocha, Leonardo; Palacios, Ricardo; Ramírez, Oscar; Vélez, Juan D; Epstein, Judith E; Richie, Thomas L; Arévalo-Herrera, Myriam

    2011-02-01

    A safe and reproducible Plasmodium vivax infectious challenge method is required to evaluate the efficacy of malaria vaccine candidates. Seventeen healthy Duffy (+) and five Duffy (-) subjects were randomly allocated into three (A-C) groups and were exposed to the bites of 2-4 Anopheles albimanus mosquitoes infected with Plasmodium vivax derived from three donors. Duffy (-) subjects were included as controls for each group. Clinical manifestations of malaria and parasitemia were monitored beginning 7 days post-challenge. All Duffy (+) volunteers developed patent malaria infection within 16 days after challenge. Prepatent period determined by thick smear, was longer for Group A (median 14.5 d) than for Groups B and C (median 10 d/each). Infected volunteers recovered rapidly after treatment with no serious adverse events. The bite of as low as two P. vivax-infected mosquitoes provides safe and reliable infections in malaria-naive volunteers, suitable for assessing antimalarial and vaccine efficacy trials. PMID:21292872

  4. Activities of Various 4-Aminoquinolines Against Infections with Chloroquine-Resistant Strains of Plasmodium falciparum1

    PubMed Central

    Schmidt, L. H.; Vaughan, Dennis; Mueller, Donna; Crosby, Ruth; Hamilton, Rebecca

    1977-01-01

    The studies reported here stemmed from a personal report by Geiman on the capacity of the 4-aminoquinoline amodiaquin to inhibit in vitro maturation of ring stages of the chloroquine-resistant Monterey strain of Plasmodium falciparum. This observation, confirmed in owl monkeys infected with this strain, led to a comparison of the activities of chloroquine, amodiaquin, amopyroquin, and dichlorquinazine (12,278 RP) against infections with various chloroquine-susceptible and chloroquine-resistant strains. The results showed that: (i) these 4-aminoquinolines were essentially equally active against infections with chloroquine-susceptible strains and (ii) the activities of amodiaquin, amopyroquin, and dichlorquinazine were reduced significantly in the face of chloroquine resistance, but (iii) well-tolerated doses of these compounds would cure infections with strains that fully resisted treatment with maximally tolerated doses of chloroquine. Two other 4-aminoquinolines, SN-8137 and SN-9584, which also exhibited activity against chloroquine-resistant parasites in vitro, displayed curative activity in monkeys infected with a chloroquine-resistant strain. These observations show that there is cross-resistance among the 4-aminoquinolines, confirming earlier findings, but indicate that the dimensions of this phenomenon are sufficiently limited so that some derivatives are therapeutically effective against infections refractory to maximally tolerated doses of chloroquine. PMID:406829

  5. Using infective mosquitoes to challenge monkeys with Plasmodium knowlesi in malaria vaccine studies

    PubMed Central

    2014-01-01

    Background When rhesus monkeys (Macaca mulatta) are used to test malaria vaccines, animals are often challenged by the intravenous injection of sporozoites. However, natural exposure to malaria comes via mosquito bite, and antibodies can neutralize sporozoites as they traverse the skin. Thus, intravenous injection may not fairly assess humoral immunity from anti-sporozoite malaria vaccines. To better assess malaria vaccines in rhesus, a method to challenge large numbers of monkeys by mosquito bite was developed. Methods Several species and strains of mosquitoes were tested for their ability to produce Plasmodium knowlesi sporozoites. Donor monkey parasitaemia effects on oocyst and sporozoite numbers and mosquito mortality were documented. Methylparaben added to mosquito feed was tested to improve mosquito survival. To determine the number of bites needed to infect a monkey, animals were exposed to various numbers of P. knowlesi-infected mosquitoes. Finally, P. knowlesi-infected mosquitoes were used to challenge 17 monkeys in a malaria vaccine trial, and the effect of number of infectious bites on monkey parasitaemia was documented. Results Anopheles dirus, Anopheles crascens, and Anopheles dirus X (a cross between the two species) produced large numbers of P. knowlesi sporozoites. Mosquito survival to day 14, when sporozoites fill the salivary glands, averaged only 32% when donor monkeys had a parasitaemia above 2%. However, when donor monkey parasitaemia was below 2%, mosquitoes survived twice as well and contained ample sporozoites in their salivary glands. Adding methylparaben to sugar solutions did not improve survival of infected mosquitoes. Plasmodium knowlesi was very infectious, with all monkeys developing blood stage infections if one or more infected mosquitoes successfully fed. There was also a dose-response, with monkeys that received higher numbers of infected mosquito bites developing malaria sooner. Conclusions Anopheles dirus, An. crascens and a

  6. 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

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

    PubMed

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

    2015-01-01

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

  8. Associations Between Helminth Infections, Plasmodium falciparum Parasite Carriage and Antibody Responses to Sexual and Asexual Stage Malarial Antigens.

    PubMed

    Ateba-Ngoa, Ulysse; Jones, Sophie; Zinsou, Jeannot Fréjus; Honkpehedji, Josiane; Adegnika, Ayola Akim; Agobe, Jean-Claude Dejon; Massinga-Loembe, Marguerite; Mordmüller, Benjamin; Bousema, Teun; Yazdanbakhsh, Maria

    2016-08-01

    Infections with helminths and Plasmodium spp. overlap in their geographical distribution. It has been postulated that helminth infections may influence malarial transmission by altering Plasmodium falciparum gametocytogenesis. This cross-sectional study assessed the effect of helminth infections on P. falciparum gametocyte carriage and on humoral immune responses to sexual stage antigens in Gabon. Schistosoma haematobium and filarial infections as well as P. falciparum asexual forms and gametocyte carriage were determined. The antibody responses measured were to sexual (Pfs230, Pfs48/45) and asexual P. falciparum antigens (AMA1, MSP1, and GLURP). A total of 287 subjects were included. The prevalence of microscopically detectable P. falciparum asexual parasites was higher in S. haematobium-infected subjects in comparison to their uninfected counterparts (47% versus 26%, P = 0.003), but this was not different when filarial infections were considered. Plasmodium falciparum gametocyte carriage was similar between Schistosoma- or filaria-infected and uninfected subjects. We observed a significant decrease of Pfs48/45 immunoglobulin G titer in S. haematobium-infected subjects (P = 0.037), whereas no difference was seen for Pfs230 antibody titer, nor for antibodies to AMA1, MSP1, or GLURP. Our findings suggest an effect of S. haematobium on antibody responses to some P. falciparum gametocyte antigens that may have consequences for transmission-blocking immunity. PMID:27273645

  9. Gestational malaria associated to Plasmodium vivax and Plasmodium falciparum placental mixed-infection followed by foetal loss: a case report from an unstable transmission area in Brazil.

    PubMed

    Carvalho, Bruna O; Matsuda, Joycenéa S; Luz, Sergio L B; Martinez-Espinosa, Flor E; Leite, Juliana A; Franzin, Fernanda; Orlandi, Patrícia P; Gregoracci, Gustavo B; Lacerda, Marcus V G; Nogueira, Paulo A; Costa, Fabio T M

    2011-01-01

    Gestational malaria is a multi-factorial syndrome leading to poor outcomes for both the mother and foetus. Although an unusual increasing in the number of hospitalizations caused by Plasmodium vivax has been reported in Brazil, mortality is rarely observed. This is a report of a gestational malaria case that occurred in the city of Manaus (Amazonas State, Brazil) and resulted in foetal loss. The patient presented placental mixed-infection by Plasmodium vivax and Plasmodium falciparum after diagnosis by nested-PCR, however microscopic analysis failed to detect P. falciparum in the peripheral blood. Furthermore, as the patient did not receive proper treatment for P. falciparum and hospitalization occurred soon after drug treatment, it seems that P. falciparum pathology was modulated by the concurrent presence of P. vivax. Collectively, this case confirms the tropism towards the placenta by both of these species of parasites, reinforces the notion that co-existence of distinct malaria parasites interferes on diseases' outcomes, and opens discussions regarding diagnostic methods, malaria treatment during pregnancy and prenatal care for women living in unstable transmission areas of malaria, such as the Brazilian Amazon. PMID:21708032

  10. Concomitant infections of Plasmodium falciparum and Wuchereria bancrofti on the Kenyan coast

    PubMed Central

    Muturi, Ephantus J; Mbogo, Charles M; Mwangangi, Joseph M; Ng'ang'a, Zipporah W; Kabiru, Ephantus W; Mwandawiro, Charles; Beier, John C

    2006-01-01

    Background Anopheles gambiae s.l. and An. funestus are important vectors of malaria and bancroftian filariasis, which occur as co-endemic infections along the Kenyan Coast. However, little is known about the occurrence and prevalence of concomitant infections of the two diseases in mosquito and human populations in these areas. This study reports the prevalence of concomitant infections of Plasmodium falciparum and Wuchereria bancrofti in mosquito and human populations in Jilore and Shakahola villages in Malindi, Kenya. Methods Mosquitoes were sampled inside houses by pyrethrum spray sheet collection (PSC) while blood samples were collected by finger prick technique at the end of entomological survey. Results A total of 1,979 female Anopheles mosquitoes comprising of 1,919 Anopheles gambiae s.l and 60 An. funestus were collected. Concomitant infections of P. falciparum sporozoites and filarial worms occurred in 1.1% and 1.6% of An. gambiae s.l collected in Jilore and Shakahola villages respectively. Wuchereria-infected mosquitoes had higher sporozoite rates compared to non-infected mosquitoes, but multiple infections appeared to reduce mosquito survivorship making transmission of such infections rare. None of the persons examined in Shakahola (n = 107) had coinfections of the two parasites, whereas in Jilore (n = 94), out of the 4.3% of individuals harbouring both parasites, 1.2% had P. falciparum gametocytes and microfilariae and could potentially infect the mosquito with both parasites simultaneously. Conclusion Concerted efforts should be made to integrate the control of malaria and bancroftian filariasis in areas where they co-exist. PMID:16723020

  11. Controlled Human Malaria Infection of Tanzanians by Intradermal Injection of Aseptic, Purified, Cryopreserved Plasmodium falciparum Sporozoites

    PubMed Central

    Shekalaghe, Seif; Rutaihwa, Mastidia; Billingsley, Peter F.; Chemba, Mwajuma; Daubenberger, Claudia A.; James, Eric R.; Mpina, Maximillian; Ali Juma, Omar; Schindler, Tobias; Huber, Eric; Gunasekera, Anusha; Manoj, Anita; Simon, Beatus; Saverino, Elizabeth; Church, L. W. Preston; Hermsen, Cornelus C.; Sauerwein, Robert W.; Plowe, Christopher; Venkatesan, Meera; Sasi, Philip; Lweno, Omar; Mutani, Paul; Hamad, Ali; Mohammed, Ali; Urassa, Alwisa; Mzee, Tutu; Padilla, Debbie; Ruben, Adam; Lee Sim, B. Kim; Tanner, Marcel; Abdulla, Salim; Hoffman, Stephen L.

    2014-01-01

    Controlled human malaria infection (CHMI) by mosquito bite has been used to assess anti-malaria interventions in > 1,500 volunteers since development of methods for infecting mosquitoes by feeding on Plasmodium falciparum (Pf) gametocyte cultures. Such CHMIs have never been used in Africa. Aseptic, purified, cryopreserved Pf sporozoites, PfSPZ Challenge, were used to infect Dutch volunteers by intradermal injection. We conducted a double-blind, placebo-controlled trial to assess safety and infectivity of PfSPZ Challenge in adult male Tanzanians. Volunteers were injected intradermally with 10,000 (N = 12) or 25,000 (N = 12) PfSPZ or normal saline (N = 6). PfSPZ Challenge was well tolerated and safe. Eleven of 12 and 10 of 11 subjects, who received 10,000 and 25,000 PfSPZ respectively, developed parasitemia. In 10,000 versus 25,000 PfSPZ groups geometric mean days from injection to Pf positivity by thick blood film was 15.4 versus 13.5 (P = 0.023). Alpha-thalassemia heterozygosity had no apparent effect on infectivity. PfSPZ Challenge was safe, well tolerated, and infectious. PMID:25070995

  12. 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

  13. An immunomics approach for the analysis of natural antibody responses to Plasmodium vivax infection.

    PubMed

    Chen, Jun-Hu; Chen, Shen-Bo; Wang, Yue; Ju, Chuan; Zhang, Ting; Xu, Bin; Shen, Hai-Mo; Mo, Xiao-Jin; Molina, Douglas M; Eng, Michael; Liang, Xiaowu; Gardner, Malcolm J; Wang, Ruobing; Hu, Wei

    2015-08-01

    High throughput immunomics is a powerful platform to discover potential targets of host immunity and develop diagnostic tests for infectious diseases. We screened the sera of Plasmodium vivax-exposed individuals to profile the antibody response to blood-stage antigens of P. vivax using a P. vivax protein microarray. A total of 1936 genes encoding the P. vivax proteins were expressed, printed and screened with sera from P. vivax-exposed individuals and normal subjects. Total of 151 (7.8% of the 1936 targets) highly immunoreactive antigens were identified, including five well-characterized antigens of P. vivax (ETRAMP11.2, Pv34, SUB1, RAP2 and MSP4). Among the highly immunoreactive antigens, 5 antigens were predicted as adhesins by MAAP, and 11 antigens were predicted as merozoite invasion-related proteins based on homology with P. falciparum proteins. There are 40 proteins that have serodiagnostic potential for antibody surveillance. These novel Plasmodium antigens identified provide the clues for understanding host immune response to P. vivax infection and the development of antibody surveillance tools. PMID:26091354

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

    PubMed Central

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

    2009-01-01

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

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

    PubMed Central

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

    2015-01-01

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

  16. Short Report: Detection of the Dihydrofolate Reductase–164L Mutation in Plasmodium falciparum Infections from Malawi by Heteroduplex Tracking Assay

    PubMed Central

    Juliano, Jonathan J.; Trottman, Paul; Mwapasa, Victor; Meshnick, Steven R.

    2008-01-01

    Standard polymerase chain reaction methods often cannot detect drug-resistance mutations in Plasmodium falciparum infections if the mutation is present in ≤ 20% of the parasites. A heteroduplex tracking assay was developed that can detect dihydrofolate reductase 164-L mutations in variants representing 1% of the parasites in an individual host. Using this assay, we confirmed the presence of the mutation in P. falciparum infections in Malawi. PMID:18541765

  17. Implications of Plasmodium parasite infected mosquitoes on an insular avifauna: the case of Socorro Island, México.

    PubMed

    Carlson, Jenny S; Martínez-Gómez, Juan E; Cornel, Anthony; Loiseau, Claire; Sehgal, Ravinder N M

    2011-06-01

    Avian malaria (Plasmodium spp.) has been implicated in the decline of avian populations in the Hawaiian Islands and it is generally agreed that geographically isolated and immunologically naïve bird populations are particularly vulnerable to the pathogenic effects of invasive malaria parasites. In order to assess the potential disease risk of malaria to the avifauna of Socorro Island, México, we surveyed for Plasmodium isolates from 1,300 resident field-caught mosquitoes. Most of them were identified as Aedes (Ochlerotatus) taeniorhynchus (Wiedemann, 1821), which were abundant in the salt marshes. We also collected Culex quinquefasciatus Say, 1823 close to human dwellings. Mitochondrial ND5 and COII gene sequences of Ae. taeniorhynchus were analyzed and compared to corresponding sequences of mosquitoes of the Galápagos Islands, Latin America, and the North American mainland. Aedes lineages from Socorro Island clustered most closely with a lineage from the continental U.S. Plasmodium spp. DNA was isolated from both species of mosquitoes. From 38 positive pools, we isolated 11 distinct mitochondrial Cytb lineages of Plasmodium spp. Seven of the Plasmodium lineages represent previously documented avian infective strains while four were new lineages. Our results confirm a potential risk for the spread of avian malaria and underscore the need to monitor both the mosquito and avian populations as a necessary conservation measure to protect endangered bird species on Socorro Island. PMID:21635660

  18. Effect of HIV Infection and Plasmodium falciparum Parasitemia on Pregnancy Outcomes in Malawi

    PubMed Central

    Nkhoma, Ella T.; Kalilani-Phiri, Linda; Mwapasa, Victor; Rogerson, Stephen J.; Meshnick, Steven R.

    2012-01-01

    Plasmodium falciparum and human immunodeficiency virus (HIV) are both risk factors for low birth weight (LBW) and maternal anemia, and they may interact to increase risk of adverse pregnancy outcomes. In 2005 and 2006, we followed 831 pregnant women attending antenatal care clinics in southern Malawi through delivery. HIV was associated with increased risk of LBW (adjusted prevalence ratio [PRadj] = 3.08, 95% confidence interval [CI] = 1.40, 6.79). Having greater than or equal to three episodes of peripheral parasitemia was also associated with increased risk of LBW (PRadj = 2.68, 95% CI = 1.06, 6.79). Among multigravidae, dual infection resulted in 9.59 (95% CI = 2.51, 36.6) times the risk of LBW compared with uninfected multigravidae. HIV infection and placental parasitemia were each associated with increased risk of anemia. Thus, HIV infection and parasitemia are important independent risk factors for adverse pregnancy outcomes. Among multigravidae, HIV infection and placental parasitemia may interact to produce an impact greater than the sum of their independent effects. PMID:22764288

  19. Intravital Placenta Imaging Reveals Microcirculatory Dynamics Impact on Sequestration and Phagocytosis of Plasmodium-Infected Erythrocytes

    PubMed Central

    de Moraes, Luciana Vieira; Tadokoro, Carlos Eduardo; Gómez-Conde, Iván; Olivieri, David N.; Penha-Gonçalves, Carlos

    2013-01-01

    Malaria in pregnancy is exquisitely aggressive, causing a range of adverse maternal and fetal outcomes prominently linked to Plasmodium-infected erythrocyte cytoadherence to fetal trophoblast. To elucidate the physiopathology of infected erythrocytes (IE) sequestration in the placenta we devised an experimental system for intravital placental examination of P. berghei-infected mice. BALB/c females were mated to C57Bl/6 CFP+ male mice and infected with GFP+ P. berghei IE, and at gestational day 18, placentas were exposed for time-lapse imaging acquisition under two-photon microscopy. Real-time images and quantitative measurements revealed that trophoblast conformational changes transiently restrain blood flow in the mouse placental labyrinth. The complex dynamics of placental microcirculation promotes IE accumulation in maternal blood spaces with low blood flow and allows the establishment of stable IE-trophoblast contacts. Further, we show that the fate of sequestered IE includes engulfment by both macrophagic and trophoblastic fetal-derived cells. These findings reinforce the current paradigm that IE interact with the trophoblast and provide definitive evidence on two novel pathogenesis mechanisms: (1) trophoblast layer controls placental microcirculation promoting IE sequestration; and (2) fetal-derived placental cells engulf sequestered IE. PMID:23382682

  20. Dynamics in the Cytoadherence Phenotypes of Plasmodium falciparum Infected Erythrocytes Isolated during Pregnancy

    PubMed Central

    Doritchamou, Justin; Sossou-tchatcha, Sylvain; Cottrell, Gilles; Moussiliou, Azizath; Hounton Houngbeme, Christophe; Massougbodji, Achille; Deloron, Philippe; Ndam, Nicaise Tuikue

    2014-01-01

    Pregnant women become susceptible to malaria infection despite their acquired immunity to this disease from childhood. The placental sequestration of Plasmodium falciparum infected erythrocytes (IE) is the major feature of malaria during pregnancy, due to ability of these parasites to bind chondroitin sulfate A (CSA) in the placenta through the VAR2CSA protein that parasites express on the surface of IE. We collected parasites at different times of pregnancy and investigated the adhesion pattern of freshly collected isolates on the three well described host receptors (CSPG, CD36 and ICAM-1). Var genes transcription profile and VAR2CSA surface-expression were assessed in these isolates. Although adhesion of IE to CD36 and ICAM-1 was observed in some isolates, CSA-adhesion was the predominant binding feature in all isolates analyzed. Co-existence in the peripheral blood of several adhesion phenotypes in early pregnancy isolates was observed, a diversity that gradually tightens with gestational age in favour of the CSA-adhesion phenotype. Infections occurring in primigravidae were often by parasites that adhered more to CSA than those from multigravidae. Data from this study further emphasize the specificity of CSA adhesion and VAR2CSA expression by parasites responsible for pregnancy malaria, while drawing attention to the phenotypic complexity of infections occurring early in pregnancy as well as in multigravidae. PMID:24905223

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

    PubMed

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

    1985-11-01

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

  2. Novel Inhibitor of Plasmodium Histone Deacetylase That Cures P. berghei-Infected Mice▿

    PubMed Central

    Agbor-Enoh, S.; Seudieu, C.; Davidson, E.; Dritschilo, A.; Jung, M.

    2009-01-01

    Histone deacetylases (HDAC) are potential targets for the development of new antimalarial drugs. The growth of Plasmodium falciparum and other apicomplexans can be suppressed in the presence of potent HDAC inhibitors in vitro and in vivo; however, in vivo parasite suppression is generally incomplete or reversible after the discontinuation of drug treatment. Furthermore, most established HDAC inhibitors concurrently show broad toxicities against parasites and human cells and high drug concentrations are required for effective antimalarial activity. Here, we report on HDAC inhibitors that are potent against P. falciparum at subnanomolar concentrations and that have high selectivities; the lead compounds have mean 50% inhibitory concentrations for the killing of the malaria parasite up to 950 times lower than those for the killing of mammalian cells. These potential drugs improved survival and completely and irreversibly suppressed parasitemia in P. berghei-infected mice. PMID:19223622

  3. Analysis of Plasmodium falciparum diversity in natural infections by deep sequencing

    PubMed Central

    Manske, Magnus; Miotto, Olivo; Campino, Susana; Auburn, Sarah; Almagro-Garcia, Jacob; Maslen, Gareth; O’Brien, Jack; Djimde, Abdoulaye; Doumbo, Ogobara; Zongo, Issaka; Ouedraogo, Jean-Bosco; Michon, Pascal; Mueller, Ivo; Siba, Peter; Nzila, Alexis; Borrmann, Steffen; Kiara, Steven M.; Marsh, Kevin; Jiang, Hongying; Su, Xin-Zhuan; Amaratunga, Chanaki; Fairhurst, Rick; Socheat, Duong; Nosten, Francois; Imwong, Mallika; White, Nicholas J.; Sanders, Mandy; Anastasi, Elisa; Alcock, Dan; Drury, Eleanor; Oyola, Samuel; Quail, Michael A.; Turner, Daniel J.; Rubio, Valentin Ruano; Jyothi, Dushyanth; Amenga-Etego, Lucas; Hubbart, Christina; Jeffreys, Anna; Rowlands, Kate; Sutherland, Colin; Roper, Cally; Mangano, Valentina; Modiano, David; Tan, John C.; Ferdig, Michael T.; Amambua-Ngwa, Alfred; Conway, David J.; Takala-Harrison, Shannon; Plowe, Christopher V.; Rayner, Julian C.; Rockett, Kirk A.; Clark, Taane G.; Newbold, Chris I.; Berriman, Matthew; MacInnis, Bronwyn; Kwiatkowski, Dominic P.

    2013-01-01

    Malaria elimination strategies require surveillance of the parasite population for genetic changes that demand a public health response, such as new forms of drug resistance. 1,2 Here we describe methods for large-scale analysis of genetic variation in Plasmodium falciparum by deep sequencing of parasite DNA obtained from the blood of patients with malaria, either directly or after short term culture. Analysis of 86,158 exonic SNPs that passed genotyping quality control in 227 samples from Africa, Asia and Oceania provides genome-wide estimates of allele frequency distribution, population structure and linkage disequilibrium. By comparing the genetic diversity of individual infections with that of the local parasite population, we derive a metric of within-host diversity that is related to the level of inbreeding in the population. An open-access web application has been established for exploration of regional differences in allele frequency and of highly differentiated loci in the P. falciparum genome. PMID:22722859

  4. Optimizing Intradermal Administration of Cryopreserved Plasmodium falciparum Sporozoites in Controlled Human Malaria Infection

    PubMed Central

    Lyke, Kirsten E.; Laurens, Matthew B.; Strauss, Kathy; Adams, Matthew; Billingsley, Peter F.; James, Eric; Manoj, Anita; Chakravarty, Sumana; Plowe, Christopher V.; Li, Ming Lin; Ruben, Adam; Edelman, Robert; Green, Michael; Dube, Tina J.; Kim Lee Sim, B.; Hoffman, Stephen L.

    2015-01-01

    Controlled human malaria infection (CHMI) is a powerful tool to evaluate malaria vaccine and prophylactic drug efficacy. Until recently CHMI was only carried out by the bite of infected mosquitoes. A parenteral method of CHMI would standardize Plasmodium falciparum sporozoite (PfSPZ) administration, eliminate the need for expensive challenge facility infrastructure, and allow for use of many P. falciparum strains. Recently, intradermal (ID) injection of aseptic, purified, cryopreserved PfSPZ was shown to induce P. falciparum malaria; however, 100% infection rates were not achieved by ID injection. To optimize ID PfSPZ dosing so as to achieve 100% infection, 30 adults aged 18–45 years were randomized to one of six groups composed of five volunteers each. The parameters of dose (1 × 104 versus 5 × 104 PfSPZ total dose per volunteer), number of injections (two versus eight), and aliquot volume per ID injection (10 μL versus 50 μL) were studied. Three groups attained 100% infection: 1 × 104 PfSPZ in 50 μL/2 doses, 1 × 104 PfSPZ in 10 μL/2 doses, and 5 × 104 PfSPZ in 10 μL/8 doses. The group that received 5 × 104 PfSPZ total dose in eight 10 μL injections had a 100% infection rate and the shortest prepatent period (mean of 12.7 days), approaching the prepatent period for the current CHMI standard of five infected mosquitoes. PMID:26416102

  5. Placental Microparticles and MicroRNAs in Pregnant Women with Plasmodium falciparum or HIV Infection

    PubMed Central

    Moro, Laura; Bardají, Azucena; Macete, Eusebio; Barrios, Diana; Morales-Prieto, Diana M.; España, Carolina; Mandomando, Inacio; Sigaúque, Betuel; Dobaño, Carlota; Markert, Udo R.; Benitez-Ribas, Daniel; Alonso, Pedro L.; Menéndez, Clara; Mayor, Alfredo

    2016-01-01

    Background During pregnancy, syncytiotrophoblast vesicles contribute to maternal tolerance towards the fetus, but also to pathologies such as pre-eclampsia. The aim of the study was to address whether Plasmodium falciparum and HIV infections in pregnancy affect the secretion, microRNA content and function of trophoblast microparticles. Methods Microparticles were isolated and characterized from 122 peripheral plasmas of Mozambican pregnant women, malaria- and/or HIV-infected and non-infected. Expression of placenta-related microRNAs in microparticles was analysed by qPCR and the effect of circulating microparticles on dendritic cells assessed by phenotype analysis and cytokine/chemokine measurement. Results Concentrations of total and trophoblast microparticles detected by flow cytometry were higher in HIV-positive (P = 0.005 and P = 0.030, respectively) compared to non-infected mothers, as well as in women delivering low birthweight newborns (P = 0.032 and P = 0.021, respectively). miR-517c was overexpressed in mothers with placental malaria (P = 0.034), compared to non-infected. Microparticles from HIV-positive induced a higher expression of MHCII (P = 0.021) and lower production of MCP1 (P = 0.008) than microparticles from non-infected women. Conclusions In summary, alterations in total and trophoblast microparticles associated with malaria and HIV in pregnant women may have an immunopathogenic role. The potential for placental-derived vesicles and microRNAs as biomarkers of adverse outcomes during pregnancy and malaria infection should be confirmed in future studies. PMID:26757431

  6. Development of a Single Nucleotide Polymorphism Barcode to Genotype Plasmodium vivax Infections

    PubMed Central

    Baniecki, Mary Lynn; Faust, Aubrey L.; Schaffner, Stephen F.; Park, Daniel J.; Galinsky, Kevin; Daniels, Rachel F.; Hamilton, Elizabeth; Ferreira, Marcelo U.; Karunaweera, Nadira D.; Serre, David; Zimmerman, Peter A.; Sá, Juliana M.; Wellems, Thomas E.; Musset, Lise; Legrand, Eric; Melnikov, Alexandre; Neafsey, Daniel E.; Volkman, Sarah K.; Wirth, Dyann F.; Sabeti, Pardis C.

    2015-01-01

    Plasmodium vivax, one of the five species of Plasmodium parasites that cause human malaria, is responsible for 25–40% of malaria cases worldwide. Malaria global elimination efforts will benefit from accurate and effective genotyping tools that will provide insight into the population genetics and diversity of this parasite. The recent sequencing of P. vivax isolates from South America, Africa, and Asia presents a new opportunity by uncovering thousands of novel single nucleotide polymorphisms (SNPs). Genotyping a selection of these SNPs provides a robust, low-cost method of identifying parasite infections through their unique genetic signature or barcode. Based on our experience in generating a SNP barcode for P. falciparum using High Resolution Melting (HRM), we have developed a similar tool for P. vivax. We selected globally polymorphic SNPs from available P. vivax genome sequence data that were located in putatively selectively neutral sites (i.e., intergenic, intronic, or 4-fold degenerate coding). From these candidate SNPs we defined a barcode consisting of 42 SNPs. We analyzed the performance of the 42-SNP barcode on 87 P. vivax clinical samples from parasite populations in South America (Brazil, French Guiana), Africa (Ethiopia) and Asia (Sri Lanka). We found that the P. vivax barcode is robust, as it requires only a small quantity of DNA (limit of detection 0.3 ng/μl) to yield reproducible genotype calls, and detects polymorphic genotypes with high sensitivity. The markers are informative across all clinical samples evaluated (average minor allele frequency > 0.1). Population genetic and statistical analyses show the barcode captures high degrees of population diversity and differentiates geographically distinct populations. Our 42-SNP barcode provides a robust, informative, and standardized genetic marker set that accurately identifies a genomic signature for P. vivax infections. PMID:25781890

  7. Development of a single nucleotide polymorphism barcode to genotype Plasmodium vivax infections.

    PubMed

    Baniecki, Mary Lynn; Faust, Aubrey L; Schaffner, Stephen F; Park, Daniel J; Galinsky, Kevin; Daniels, Rachel F; Hamilton, Elizabeth; Ferreira, Marcelo U; Karunaweera, Nadira D; Serre, David; Zimmerman, Peter A; Sá, Juliana M; Wellems, Thomas E; Musset, Lise; Legrand, Eric; Melnikov, Alexandre; Neafsey, Daniel E; Volkman, Sarah K; Wirth, Dyann F; Sabeti, Pardis C

    2015-03-01

    Plasmodium vivax, one of the five species of Plasmodium parasites that cause human malaria, is responsible for 25-40% of malaria cases worldwide. Malaria global elimination efforts will benefit from accurate and effective genotyping tools that will provide insight into the population genetics and diversity of this parasite. The recent sequencing of P. vivax isolates from South America, Africa, and Asia presents a new opportunity by uncovering thousands of novel single nucleotide polymorphisms (SNPs). Genotyping a selection of these SNPs provides a robust, low-cost method of identifying parasite infections through their unique genetic signature or barcode. Based on our experience in generating a SNP barcode for P. falciparum using High Resolution Melting (HRM), we have developed a similar tool for P. vivax. We selected globally polymorphic SNPs from available P. vivax genome sequence data that were located in putatively selectively neutral sites (i.e., intergenic, intronic, or 4-fold degenerate coding). From these candidate SNPs we defined a barcode consisting of 42 SNPs. We analyzed the performance of the 42-SNP barcode on 87 P. vivax clinical samples from parasite populations in South America (Brazil, French Guiana), Africa (Ethiopia) and Asia (Sri Lanka). We found that the P. vivax barcode is robust, as it requires only a small quantity of DNA (limit of detection 0.3 ng/μl) to yield reproducible genotype calls, and detects polymorphic genotypes with high sensitivity. The markers are informative across all clinical samples evaluated (average minor allele frequency > 0.1). Population genetic and statistical analyses show the barcode captures high degrees of population diversity and differentiates geographically distinct populations. Our 42-SNP barcode provides a robust, informative, and standardized genetic marker set that accurately identifies a genomic signature for P. vivax infections. PMID:25781890

  8. Characteristic Age Distribution of Plasmodium vivax Infections after Malaria Elimination on Aneityum Island, Vanuatu

    PubMed Central

    Chaves, Luis F.; Taleo, George; Kalkoa, Morris; Isozumi, Rie; Wickremasinghe, Renu; Perlmann, Hedvig; Takeo, Satoru; Tsuboi, Takafumi; Tachibana, Shin-Ichiro; Kimura, Masatsugu; Björkman, Anders; Troye-Blomberg, Marita; Tanabe, Kazuyuki; Drakeley, Chris

    2014-01-01

    Resurgence is a major concern after malaria elimination. After the initiation of the elimination program on Aneityum Island in 1991, microscopy showed that Plasmodium falciparum disappeared immediately, whereas P. vivax disappeared from 1996 onward, until P. vivax cases were reported in January 2002. By conducting malariometric surveys of the entire population of Aneityum, we investigated the age distribution of individuals with parasites during this epidemic in the context of antimalarial antibody levels and parasite antigen diversity. In July 2002, P. vivax infections were detected by microscopy in 22/759 individuals: 20/298 born after the beginning of the elimination program in 1991, 2/126 born between 1982 and 1991, and none of 335 born before 1982. PCR increased the number of infections detected to 77, distributed among all age groups. Prevalences were 12.1%, 16.7%, and 6.0%, respectively (P < 0.001). In November, a similar age pattern was found, but with fewer infections: 6/746 and 39/741 individuals were found to be infected by microscopy and PCR, respectively. The frequencies of antibody responses to P. vivax were significantly higher in individuals born before 1991 than in younger age groups and were similar to those on Malakula Island, an area of endemicity. Remarkably low antigen diversity (h, 0.15) of P. vivax infections was observed on Aneityum compared with the other islands (h, 0.89 to 1.0). A P. vivax resurgence was observed among children and teenagers on Aneityum, an age distribution similar to those before elimination and on islands where P. vivax is endemic, suggesting that in the absence of significant exposure, immunity may persist, limiting infection levels in adults. The limited parasite gene pool on islands may contribute to this protection. PMID:24166950

  9. Parity and Placental Infection Affect Antibody Responses against Plasmodium falciparum during Pregnancy▿ †

    PubMed Central

    Mayor, Alfredo; Rovira-Vallbona, Eduard; Machevo, Sonia; Bassat, Quique; Aguilar, Ruth; Quintó, Llorenç; Jiménez, Alfons; Sigauque, Betuel; Dobaño, Carlota; Kumar, Sanjeev; Singh, Bijender; Gupta, Puneet; Chauhan, Virander S.; Chitnis, Chetan E.; Alonso, Pedro L.; Menéndez, Clara

    2011-01-01

    Women are at higher risk of Plasmodium falciparum infection when pregnant. The decreasing risk of malaria with subsequent pregnancies is attributed to parity-dependent acquisition of antibodies against placental parasites expressing variant surface antigens, VAR2CSA, that mediate placental sequestration through adhesion to chondroitin sulfate A (CSA). However, modulation of immunity during pregnancy may also contribute to increase the risk of malaria. We compared antibody responses among 30 Mozambican primigravidae and 60 multigravidae at delivery, 40 men, and 40 children. IgG levels were measured against the surface antigens of erythrocytes infected with P. falciparum isolated from 12 pregnant women (4 placental and 8 peripheral blood isolates) and 26 nonpregnant hosts. We also measured IgG levels against merozoite recombinant antigens and total IgG. Placental P. falciparum infection was associated with increased levels of total IgG as well as IgG levels against merozoite antigens and parasite isolates from pregnant and nonpregnant hosts. We therefore stratified comparisons of antibody levels by placental infection. Compared to multigravidae, uninfected primigravidae had lower total IgG as well as lower levels of IgGs against peripheral blood isolates from both pregnant and nonpregnant hosts. These differences were not explained by use of bed nets, season at delivery, neighborhood of residence, or age. Compared to men, infected primigravidae had higher levels of IgGs against isolates from pregnant women and CSA-binding lines but not against other isolates, supporting the concept of a pregnancy-specific development of immunity to these parasite variants. Results of this study show that parity and placental infection can modulate immune responses during pregnancy against malaria parasites. PMID:21300778

  10. 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

  11. Isolation and Analysis of Brain-sequestered Leukocytes from Plasmodium berghei ANKA-infected Mice

    PubMed Central

    Ryg-Cornejo, Victoria; Ioannidis, Lisa J.; Hansen, Diana S.

    2013-01-01

    We describe a method for isolation and characterization of adherent inflammatory cells from brain blood vessels of P. berghei ANKA-infected mice. Infection of susceptible mouse-strains with this parasite strain results in the induction of experimental cerebral malaria, a neurologic syndrome that recapitulates certain important aspects of Plasmodium falciparum-mediated severe malaria in humans 1,2 . Mature forms of blood-stage malaria express parasitic proteins on the surface of the infected erythrocyte, which allows them to bind to vascular endothelial cells. This process induces obstructions in blood flow, resulting in hypoxia and haemorrhages 3 and also stimulates the recruitment of inflammatory leukocytes to the site of parasite sequestration. Unlike other infections, i.e neutrotopic viruses4-6, both malaria-parasitized red blood cells (pRBC) as well as associated inflammatory leukocytes remain sequestered within blood vessels rather than infiltrating the brain parenchyma. Thus to avoid contamination of sequestered leukocytes with non-inflammatory circulating cells, extensive intracardial perfusion of infected-mice prior to organ extraction and tissue processing is required in this procedure to remove the blood compartment. After perfusion, brains are harvested and dissected in small pieces. The tissue structure is further disrupted by enzymatic treatment with Collagenase D and DNAse I. The resulting brain homogenate is then centrifuged on a Percoll gradient that allows separation of brain-sequestered leukocytes (BSL) from myelin and other tissue debris. Isolated cells are then washed, counted using a hemocytometer and stained with fluorescent antibodies for subsequent analysis by flow cytometry. This procedure allows comprehensive phenotypic characterization of inflammatory leukocytes migrating to the brain in response to various stimuli, including stroke as well as viral or parasitic infections. The method also provides a useful tool for assessment of novel

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

    PubMed

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

    2002-09-01

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

  13. Hsp70s and J proteins of Plasmodium parasites infecting rodents and primates: structure, function, clinical relevance, and drug targets.

    PubMed

    Njunge, James M; Ludewig, Michael H; Boshoff, Aileen; Pesce, Eva-Rachele; Blatch, Gregory L

    2013-01-01

    Human malaria is an economically important disease caused by single-celled parasites of the Plasmodium genus whose biology displays great evolutionary adaptation to both its mammalian host and transmitting vectors. While the parasite has multiple life cycle stages, it is in the blood stage where clinical symptoms of the disease are manifested. Following erythrocyte entry, the parasite resides in the parasitophorous vacuole and actively transports its own proteins to the erythrocyte cytosol. This host-parasite "cross-talk" results in tremendous modifications of the infected erythrocyte imparting properties that allow it to adhere to the endothelium preventing splenic clearance. The Hsp70-J protein (DnaJ/Hsp40) molecular chaperone machinery, involved in cellular protein homeostasis, is being investigated as a novel drug target in various cellular systems including malaria. In Plasmodium the diverse chaperone complement is intimately involved in infected erythrocyte remodelling associated with the development and pathogenesis of malaria. In this review, we provide an overview of the Hsp70-J protein chaperone complement in Plasmodium falciparum and compare it with other Plasmodium species including the ones that serve as experimental study models for malaria. We propose that the unique traits possessed by this machinery not only provide avenues for drug targeting but also inform the evolutionary fitness of this parasite to its environment. PMID:22920898

  14. 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

  15. Limitations of microscopy to differentiate Plasmodium species in a region co-endemic for Plasmodium falciparum, Plasmodium vivax and Plasmodium knowlesi

    PubMed Central

    2013-01-01

    Background In areas co-endemic for multiple Plasmodium species, correct diagnosis is crucial for appropriate treatment and surveillance. Species misidentification by microscopy has been reported in areas co-endemic for vivax and falciparum malaria, and may be more frequent in regions where Plasmodium knowlesi also commonly occurs. Methods This prospective study in Sabah, Malaysia, evaluated the accuracy of routine district and referral hospital-based microscopy, and microscopy performed by an experienced research microscopist, for the diagnosis of PCR-confirmed Plasmodium falciparum, P. knowlesi, and Plasmodium vivax malaria. Results A total of 304 patients with PCR-confirmed Plasmodium infection were enrolled, including 130 with P. knowlesi, 122 with P. falciparum, 43 with P. vivax, one with Plasmodium malariae and eight with mixed species infections. Among patients with P. knowlesi mono-infection, routine and cross-check microscopy both identified 94 (72%) patients as “P. malariae/P. knowlesi”; 17 (13%) and 28 (22%) respectively were identified as P. falciparum, and 13 (10%) and two (1.5%) as P. vivax. Among patients with PCR-confirmed P. falciparum, routine and cross-check microscopy identified 110/122 (90%) and 112/118 (95%) patients respectively as P. falciparum, and 8/122 (6.6%) and 5/118 (4.2%) as “P. malariae/P. knowlesi”. Among those with P. vivax, 23/43 (53%) and 34/40 (85%) were correctly diagnosed by routine and cross-check microscopy respectively, while 13/43 (30%) and 3/40 (7.5%) patients were diagnosed as “P. malariae/P. knowlesi”. Four of 13 patients with PCR-confirmed P. vivax and misdiagnosed by routine microscopy as “P. malariae/P. knowlesi” were subsequently re-admitted with P. vivax malaria. Conclusions Microscopy does not reliably distinguish between P. falciparum, P. vivax and P. knowlesi in a region where all three species frequently occur. Misdiagnosis of P. knowlesi as both P. vivax and P. falciparum, and vice versa, is

  16. Estimating Geographical Variation in the Risk of Zoonotic Plasmodium knowlesi Infection in Countries Eliminating Malaria

    PubMed Central

    Shearer, Freya M.; Huang, Zhi; Weiss, Daniel J.; Wiebe, Antoinette; Gibson, Harry S.; Battle, Katherine E.; Pigott, David M.; Brady, Oliver J.; Putaporntip, Chaturong; Jongwutiwes, Somchai; Lau, Yee Ling; Manske, Magnus; Amato, Roberto; Elyazar, Iqbal R. F.; Vythilingam, Indra; Bhatt, Samir; Gething, Peter W.; Singh, Balbir; Golding, Nick; Hay, Simon I.

    2016-01-01

    Background Infection by the simian malaria parasite, Plasmodium knowlesi, can lead to severe and fatal disease in humans, and is the most common cause of malaria in parts of Malaysia. Despite being a serious public health concern, the geographical distribution of P. knowlesi malaria risk is poorly understood because the parasite is often misidentified as one of the human malarias. Human cases have been confirmed in at least nine Southeast Asian countries, many of which are making progress towards eliminating the human malarias. Understanding the geographical distribution of P. knowlesi is important for identifying areas where malaria transmission will continue after the human malarias have been eliminated. Methodology/Principal Findings A total of 439 records of P. knowlesi infections in humans, macaque reservoir and vector species were collated. To predict spatial variation in disease risk, a model was fitted using records from countries where the infection data coverage is high. Predictions were then made throughout Southeast Asia, including regions where infection data are sparse. The resulting map predicts areas of high risk for P. knowlesi infection in a number of countries that are forecast to be malaria-free by 2025 (Malaysia, Cambodia, Thailand and Vietnam) as well as countries projected to be eliminating malaria (Myanmar, Laos, Indonesia and the Philippines). Conclusions/Significance We have produced the first map of P. knowlesi malaria risk, at a fine-scale resolution, to identify priority areas for surveillance based on regions with sparse data and high estimated risk. Our map provides an initial evidence base to better understand the spatial distribution of this disease and its potential wider contribution to malaria incidence. Considering malaria elimination goals, areas for prioritised surveillance are identified. PMID:27494405

  17. The JAK-STAT Pathway Controls Plasmodium vivax Load in Early Stages of Anopheles aquasalis Infection

    PubMed Central

    Bahia, Ana C.; Kubota, Marina S.; Tempone, Antonio J.; Araújo, Helena R. C.; Guedes, Bruno A. M.; Orfanó, Alessandra S.; Tadei, Wanderli P.; Ríos-Velásquez, Claudia M.; Han, Yeon S.; Secundino, Nágila F. C.; Barillas-Mury, Carolina

    2011-01-01

    Malaria affects 300 million people worldwide every year and 450,000 in Brazil. In coastal areas of Brazil, the main malaria vector is Anopheles aquasalis, and Plasmodium vivax is responsible for the majority of malaria cases in the Americas. Insects possess a powerful immune system to combat infections. Three pathways control the insect immune response: Toll, IMD, and JAK-STAT. Here we analyze the immune role of the A. aquasalis JAK-STAT pathway after P. vivax infection. Three genes, the transcription factor Signal Transducers and Activators of Transcription (STAT), the regulatory Protein Inhibitors of Activated STAT (PIAS) and the Nitric Oxide Synthase enzyme (NOS) were characterized. Expression of STAT and PIAS was higher in males than females and in eggs and first instar larvae when compared to larvae and pupae. RNA levels for STAT and PIAS increased 24 and 36 hours (h) after P. vivax challenge. NOS transcription increased 36 h post infection (hpi) while this protein was already detected in some midgut epithelial cells 24 hpi. Imunocytochemistry experiments using specific antibodies showed that in non-infected insects STAT and PIAS were found mostly in the fat body, while in infected mosquitoes the proteins were found in other body tissues. The knockdown of STAT by RNAi increased the number of oocysts in the midgut of A. aquasalis. This is the first clear evidence for the involvement of a specific immune pathway in the interaction of the Brazilian malaria vector A. aquasalis with P. vivax, delineating a potential target for the future development of disease controlling strategies. PMID:22069502

  18. The JAK-STAT pathway controls Plasmodium vivax load in early stages of Anopheles aquasalis infection.

    PubMed

    Bahia, Ana C; Kubota, Marina S; Tempone, Antonio J; Araújo, Helena R C; Guedes, Bruno A M; Orfanó, Alessandra S; Tadei, Wanderli P; Ríos-Velásquez, Claudia M; Han, Yeon S; Secundino, Nágila F C; Barillas-Mury, Carolina; Pimenta, Paulo F P; Traub-Csekö, Yara M

    2011-11-01

    Malaria affects 300 million people worldwide every year and 450,000 in Brazil. In coastal areas of Brazil, the main malaria vector is Anopheles aquasalis, and Plasmodium vivax is responsible for the majority of malaria cases in the Americas. Insects possess a powerful immune system to combat infections. Three pathways control the insect immune response: Toll, IMD, and JAK-STAT. Here we analyze the immune role of the A. aquasalis JAK-STAT pathway after P. vivax infection. Three genes, the transcription factor Signal Transducers and Activators of Transcription (STAT), the regulatory Protein Inhibitors of Activated STAT (PIAS) and the Nitric Oxide Synthase enzyme (NOS) were characterized. Expression of STAT and PIAS was higher in males than females and in eggs and first instar larvae when compared to larvae and pupae. RNA levels for STAT and PIAS increased 24 and 36 hours (h) after P. vivax challenge. NOS transcription increased 36 h post infection (hpi) while this protein was already detected in some midgut epithelial cells 24 hpi. Imunocytochemistry experiments using specific antibodies showed that in non-infected insects STAT and PIAS were found mostly in the fat body, while in infected mosquitoes the proteins were found in other body tissues. The knockdown of STAT by RNAi increased the number of oocysts in the midgut of A. aquasalis. This is the first clear evidence for the involvement of a specific immune pathway in the interaction of the Brazilian malaria vector A. aquasalis with P. vivax, delineating a potential target for the future development of disease controlling strategies. PMID:22069502

  19. The Plasmodium translocon of exported proteins component EXP2 is critical for establishing a patent malaria infection in mice.

    PubMed

    Kalanon, Ming; Bargieri, Daniel; Sturm, Angelika; Matthews, Kathryn; Ghosh, Sreejoyee; Goodman, Christopher D; Thiberge, Sabine; Mollard, Vanessa; McFadden, Geoffrey I; Ménard, Robert; de Koning-Ward, Tania F

    2016-03-01

    Export of most malaria proteins into the erythrocyte cytosol requires the Plasmodium translocon of exported proteins (PTEX) and a cleavable Plasmodium export element (PEXEL). In contrast, the contribution of PTEX in the liver stages and export of liver stage proteins is unknown. Here, using the FLP/FRT conditional mutatagenesis system, we generate transgenic Plasmodium berghei parasites deficient in EXP2, the putative pore-forming component of PTEX. Our data reveal that EXP2 is important for parasite growth in the liver and critical for parasite transition to the blood, with parasites impaired in their ability to generate a patent blood-stage infection. Surprisingly, whilst parasites expressing a functional PTEX machinery can efficiently export a PEXEL-bearing GFP reporter into the erythrocyte cytosol during a blood stage infection, this same reporter aggregates in large accumulations within the confines of the parasitophorous vacuole membrane during hepatocyte growth. Notably HSP101, the putative molecular motor of PTEX, could not be detected during the early liver stages of infection, which may explain why direct protein translocation of this soluble PEXEL-bearing reporter or indeed native PEXEL proteins into the hepatocyte cytosol has not been observed. This suggests that PTEX function may not be conserved between the blood and liver stages of malaria infection. PMID:26347246

  20. Triterpenoids as inhibitors of erythrocytic and liver stages of Plasmodium infections.

    PubMed

    Ramalhete, Cátia; da Cruz, Filipa P; Lopes, Dinora; Mulhovo, Silva; Rosário, Virgílio E; Prudêncio, Miguel; Ferreira, Maria-José U

    2011-12-15

    Bioassay-guided fractionation of the methanol extract of Momordica balsamina led to the isolation of two new cucurbitane-type triterpenoids, balsaminol F (1) and balsaminoside B (2), along with the known glycosylated cucurbitacins, cucurbita-5,24-diene-3β,23(R)-diol-7-O-β-D-glucopyranoside (3) and kuguaglycoside A (4). Compound 1 was acylated yielding two new triesters, triacetylbalsaminol F (5) and tribenzoylbalsaminol F (6). The structures were elucidated based on spectroscopic methods including 2D-NMR experiments (COSY, HMQC, HMBC and NOESY). Compounds 1-6, were evaluated for their antimalarial activity against the erythrocytic stages of the Plasmodium falciparum chloroquine-sensitive strain 3D7 and the chloroquine-resistant clone Dd2. Assessment of compounds (1-3 and 5, 6) activity against the liver stage of Plasmodium berghei was also performed, measuring the luminescence intensity in Huh-7 cells infected with a firefly luciferase-expressing P. berghei line, PbGFP-Luc(con). Active compounds were shown to inhibit the parasite's intracellular development rather than its ability to invade hepatic cells. Toxicity of compounds (1-3 and 5, 6) was assessed on the same cell line and on mouse primary hepatocytes through the fluorescence measurement of cell confluency. Furthermore, toxicity of compounds 1-6 towards human cells was also investigated in the MCF-7 breast cancer cell line, showing that they were not toxic or exhibited weak toxicity. In blood stages of P. falciparum, compounds 1-5 displayed antimalarial activity, revealing triacetylbalsaminol F (5) the highest antiplasmodial effects (IC(50) values: 0.4μM, 3D7; 0.2μM, Dd2). The highest antiplasmodial activity against the liver stages of P.berghei was also displayed by compound 5, with high inhibitory activity and no toxicity. PMID:22071523

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

    PubMed

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

    2016-01-01

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

  2. Disrupting rhythms in Plasmodium chabaudi: costs accrue quickly and independently of how infections are initiated

    PubMed Central

    2013-01-01

    Background In the blood, the synchronous malaria parasite, Plasmodium chabaudi, exhibits a cell-cycle rhythm of approximately 24 hours in which transitions between developmental stages occur at particular times of day in the rodent host. Previous experiments reveal that when the timing of the parasite’s cell-cycle rhythm is perturbed relative to the circadian rhythm of the host, parasites suffer a (~50%) reduction in asexual stages and gametocytes. Why it matters for parasites to have developmental schedules in synchronization with the host’s rhythm is unknown. The experiment presented here investigates this issue by: (a) validating that the performance of P. chabaudi is negatively affected by mismatch to the host circadian rhythm; (b) testing whether the effect of mismatch depends on the route of infection or the developmental stage of inoculated parasites; and, (c) examining whether the costs of mismatch are due to challenges encountered upon initial infection and/or due to ongoing circadian host processes operating during infection. Methods The experiment simultaneously perturbed the time of day infections were initiated, the stage of parasite inoculated, and the route of infection. The performance of parasites during the growth phase of infections was compared across the cross-factored treatment groups (i e, all combinations of treatments were represented). Results The data show that mismatch to host rhythms is costly for parasites, reveal that this phenomenon does not depend on the developmental stage of parasites nor the route of infection, and suggest that processes operating at the initial stages of infection are responsible for the costs of mismatch. Furthermore, mismatched parasites are less virulent, in that they cause less anaemia to their hosts. Conclusion It is beneficial for parasites to be in synchronization with their host’s rhythm, regardless of the route of infection or the parasite stage inoculated. Given that arrested cell

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

    PubMed Central

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

    2016-01-01

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

  4. Stress dependent infection cost of the human malaria agent Plasmodium falciparum on its natural vector Anopheles coluzzii.

    PubMed

    Sangare, I; Dabire, R; Yameogo, B; Da, D F; Michalakis, Y; Cohuet, A

    2014-07-01

    Unraveling selective forces that shape vector-parasite interactions has critical implications for malaria control. However, it remains unclear whether Plasmodium infection induces a fitness cost to their natural mosquito vectors. Moreover, environmental conditions are known to affect infection outcome and may impact the effect of infection on mosquito fitness. We investigated in the laboratory the effects of exposition to and infection by field isolates of Plasmodium falciparum on fecundity and survival of a major vector in the field, Anopheles coluzzii under different conditions of access to sugar resources after blood feeding. The results evidenced fitness costs induced by exposition and infection. When sugar was available after blood meal, infected and exposed mosquitoes had either reduced or equal to survival to unexposed mosquitoes while fecundity was either increased or decreased depending on the blood donor. Under strong nutritional stress, survival was reduced for exposed and infected mosquitoes in all assays. We therefore provide here evidence of an environmental-dependant reduced survival in mosquitoes exposed to infection in a natural and one of the most important parasite-mosquito species associations for human malaria transmission. PMID:24747607

  5. Immune phagocytosis of Plasmodium yoelii-infected erythrocytes by macrophages and eosinophils.

    PubMed Central

    Tosta, C E; Wedderburn, N

    1980-01-01

    Unstimulated peritoneal cells from C57Bl mice were allowed to phagocytose in vitro different mixtures of Percoll-separated parasitized and non-parasitized erythrocytes (PE and NPE) from the blood of mice infected with Plasmodium yoelii in the presence of immune and normal serum. Immune serum caused a significant enhancement of phagocytosis, and both the number of PE adhering to and/or ingested by 100 macrophages and the number of the latter cells engaged in phagocytosis was increased. The effect of immune serum was more marked when the ratio of PE/macrophages was 5--40/1, but was less at a ratio of 80/1, when considerable phagocytosis of PE occurred in the presence of normal serum. From 83--100% of the phagocytosed cells were parasitized erythrocytes, even when the ratio of PE/NPE was as low as 1/15. In the system used, macrophages were unable to discriminate between non-parasitized erythrocytes from infected mice and normal erythrocytes. Eosinophils were also observed to engage in phagocytosis of parasitized erythrocytes. Their activity was entirely dependent on immune serum and was never directed against non-parasitized red blood cells. PMID:7460387

  6. Plasmodium vivax and Mansonella ozzardi co-infection in north-western Argentina.

    PubMed

    Dantur Juri, María J; Veggiani Aybar, Cecilia A; Ortega, Eugenia S; Galante, Guillermina B; Zaidenberg, Mario O

    2013-01-01

    A case of co-infection with Plasmodium vivax and Mansonella ozzardi was detected in a blood sample from a person who had shown symptoms of malaria and lived in a city that was close to the Argentina/Bolivia border. The case was detected during a random revision of thick and thin smears from patients diagnosed with malaria from various towns and cities located in north-western Argentina between 1983 and 2001. Trophozoites of P. vivax were observed in the thin blood smear along with M. ozzardi microfilaria (larval form), which presented a long, slender, pointed anucleate tail and the absence of the sheath. This last characteristic is shared with Mansonella perstans, Mansonella streptocerca and Onchocerca volvulus. More rigorously controlled studies to detect other co-infection cases in the area as well as the possibility of importation from Bolivia into Argentina are currently ongoing. The relationship between the malaria parasite and microfilaria, the potential effect of malaria treatment on the development of M. ozzardi, and the possible impact of this microfilaria on the immunity of a person against P. vivax are all still unknown. This contribution constitutes a point of focus for future studies involving the interaction between the parasites and the potential risk that humans are exposed to. PMID:23866313

  7. Diversity, host switching and evolution of Plasmodium vivax infecting African great apes

    PubMed Central

    Prugnolle, Franck; Rougeron, Virginie; Becquart, Pierre; Berry, Antoine; Makanga, Boris; Rahola, Nil; Arnathau, Céline; Ngoubangoye, Barthélémy; Menard, Sandie; Willaume, Eric; Ayala, Francisco J.; Fontenille, Didier; Ollomo, Benjamin; Durand, Patrick; Paupy, Christophe; Renaud, François

    2013-01-01

    Plasmodium vivax is considered to be absent from Central and West Africa because of the protective effect of Duffy negativity. However, there are reports of persons returning from these areas infected with this parasite and observations suggesting the existence of transmission. Among the possible explanations for this apparent paradox, the existence of a zoonotic reservoir has been proposed. May great apes be this reservoir? We analyze the mitochondrial and nuclear genetic diversity of P. vivax parasites isolated from great apes in Africa and compare it to parasites isolated from travelers returning from these regions of Africa, as well as to human isolates distributed all over the world. We show that the P. vivax sequences from parasites of great apes form a clade genetically distinct from the parasites circulating in humans. We show that this clade’s parasites can be infectious to humans by describing the case of a traveler returning from the Central African Republic infected with one of them. The relationship between this P. vivax clade in great apes and the human isolates is discussed. PMID:23637341

  8. GENETIC CONTROL OF SUSCEPTIBILITY TO INFECTION WITH PLASMODIUM CHABAUDI CHABAUDI AS IN INBRED MOUSE STRAINS

    PubMed Central

    Laroque, Aurélie; Min-Oo, Gundula; Tam, Mifong; Radovanovic, Irena; Stevenson, Mary M.; Gros, Philippe

    2016-01-01

    To identify genetic effects modulating blood stage replication of the malarial parasite, we phenotyped a group of 25 inbred mouse strains for susceptibility to Plasmodium chabaudi chabaudi AS infection (peak parasitemia, survival). A broad spectrum of responses was observed, with strains such as C57BL/6J being the most resistant (low parasitemia, 100% survival), and strains such as NZW/LacJ and C3HeB/FeJ being extremely susceptible (very high parasitemia and uniform lethality). A number of strains showed intermediate phenotypes and gender specific effects, suggestive of rich genetic diversity in response to malaria in inbred strains. An F2 progeny were generated from SM/J (susceptible) and C57BL/6J (resistant) parental strains, and was phenotyped for susceptibility to P. chabaudi chabaudi AS. A whole genome scan in these animals identified the Char1 locus (LOD=7.40) on chromosome 9 as a key regulator of parasite density and pointed to a conserved 0.4Mb haplotype at Char1 that segregates with susceptibility/resistance to infection. In addition, a second locus was detected in [SM/J x C57BL/6J] F2 mice on the X chromosome (LOD=4.26), which was given the temporary designation Char11. These studies identify a conserved role of Char1 in regulating response to malaria in inbred mouse strains, and provide a prioritized 0.4Mb interval for the search of positional candidates. PMID:21975430

  9. Pre-erythrocytic-stage immune effector mechanisms in Plasmodium spp. infections.

    PubMed Central

    Doolan, D L; Hoffman, S L

    1997-01-01

    The potent protective immunity against malaria induced by immunization of mice and humans with radiation-attenuated Plasmodium spp. sporozoites is thought to be mediated primarily by T-cell responses directed against infected hepatocytes. This has led to considerable efforts to develop subunit vaccines that duplicate this protective immunity, but a universally effective vaccine is still not available and in vitro correlates of protective immunity have not been established. Contributing to this delay has been a lack of understanding of the mechanisms responsible for the protection. There are now data indicating that CD8+ T cells, CD4+ T cells, cytokines, and nitric oxide can all mediate the elimination of infected hepatocytes in vitro and in vivo. By dissecting the protection induced by immunization with irradiated sporozoite, DNA and synthetic peptide-adjuvant vaccines, we have demonstrated that different T-cell-dependent immune responses mediate protective immunity in the same inbred strain of mouse, depending on the method of immunization. Furthermore, the mechanism of protection induced by a single method of immunization may vary among different strains of mice. These data have important implications for the development of pre-erythrocytic-stage vaccines designed to protect a heterogeneous human population, and of assays that predict protective immunity. PMID:9355128

  10. A microfluidic model for single-cell capillary obstruction by Plasmodium falciparum-infected erythrocytes.

    PubMed

    Shelby, J Patrick; White, John; Ganesan, Karthikeyan; Rathod, Pradipsinh K; Chiu, Daniel T

    2003-12-01

    Severe malaria by Plasmodium falciparum is a potentially fatal disease, frequently unresponsive to even the most aggressive treatments. Host organ failure is associated with acquired rigidity of infected red blood cells and capillary blockage. In vitro techniques have played an important role in modeling cell deformability. Although, historically they have either been applied to bulk cell populations or to measure single physical parameters of individual cells. In this article, we demonstrate the unique abilities and benefits of elastomeric microchannels to characterize complex behaviors of single cells, under flow, in multicellular capillary blockages. Channels of 8-, 6-, 4-, and 2-microm widths were readily traversed by the 8 microm-wide, highly elastic, uninfected red blood cells, as well as by infected cells in the early ring stages. Trophozoite stages failed to freely traverse 2- to 4-microm channels; some that passed through the 4-microm channels emerged from constricted space with deformations whose shape-recovery could be observed in real time. In 2-microm channels, trophozoites mimicked "pitting," a normal process in the body where spleen beds remove parasites without destroying the red cell. Schizont forms failed to traverse even 6-microm channels and rapidly formed a capillary blockage. Interestingly, individual uninfected red blood cells readily squeezed through the blockages formed by immobile schizonts in a 6-microm capillary. The last observation can explain the high parasitemia in a growing capillary blockage and the well known benefits of early blood transfusion in severe malaria. PMID:14638939

  11. Risk factors for Plasmodium vivax infection in the Lacandon forest, southern Mexico.

    PubMed

    Danis-Lozano, R; Rodriguez, M H; Gonzalez-Ceron, L; Hernandez-Avila, M

    1999-06-01

    A study was conducted to characterize the risk of Plasmodium vivax infection in the Lacandon forest, southern Mexico. Blood samples and questionnaire data were collected in 1992. Malaria cases (n = 137) were identified by the presence of symptoms and a positive thick blood smear. The control group included individuals with negative antibody titres and no history of malaria (n = 4994). From 7628 individuals studied, 1006 had anti-P. vivax antibodies. Seroprevalence increased with age. Risk factors associated with infection included: place of birth outside the village of residence (odds ratio, OR 11.67; 95% CI 5.21-26.11); no use of medical services (OR 4.69, 95% CI 3.01-7.29), never using bed-nets (OR 3.98, 95 % CI 1.23-12.86) and poor knowledge of malaria transmission, prevention and treatment (OR 2.30, 95 % CI 1.30-4.07). Health education represents the best recommendation for controlling the disease in the area. PMID:10459651

  12. Genetic diversity and multiple infections of Plasmodium vivax malaria in Western Thailand.

    PubMed

    Cui, Liwang; Mascorro, Carlye N; Fan, Ql; Rzomp, Kimberly A; Khuntirat, Benjawan; Zhou, Guofa; Chen, Hong; Yan, Guiyun; Sattabongkot, Jetsumon

    2003-05-01

    Using two polymorphic genetic markers, the merozoite surface protein-3alpha (MSP-3alpha) and the circumsporozoite protein (CSP), we investigated the population diversity of Plasmodium vivax in Mae Sod, Thailand from April 2000 through June 2001. Genotyping the parasites isolated from 90 malaria patients attending two local clinics for the dimorphic CSP gene revealed that the majority of the parasites (77%) were the VK210 type. Genotyping the MSP3-alpha gene indicated that P. vivax populations exhibited an equally high level of polymorphism as those from Papua New Guinea, a hyperendemic region. Based on the length of polymerase chain reaction products, three major types of the MSP-3alpha locus were distinguished, with frequencies of 74.8%, 18.7%, and 6.5%, respectively. The 13 alleles distinguished by restriction fragment length polymorphism analysis did not show a significant seasonal variation in frequency. Genotyping the MSP-3alpha and CSP genes showed that 19.3% and 25.6% of the patients had multiple infections, respectively, and the combined rate was 35.6%. Comparisons of MSP-3alpha sequences from nine clones further confirmed the high level of genetic diversity of the parasite and also suggested that geographic isolation may exist. These results strongly indicate that P. vivax populations are highly diverse and multiple clonal infections are common in this malaria-hypoendemic region of Thailand. PMID:12812356

  13. Preferential targeting of human erythrocytes infected with the malaria parasite Plasmodium falciparumvia hexose transporter surface proteins.

    PubMed

    Heikham, Kajal Devi; Gupta, Ankit; Kumar, Ambrish; Singh, Chandan; Saxena, Juhi; Srivastava, Kumkum; Puri, Sunil K; Dwivedi, Anil K; Habib, Saman; Misra, Amit

    2015-04-10

    Glucose uptake by Plasmodium-infected erythrocytes (RBC) is higher compared to uninfected RBC. Glucose is transported across the cell membrane by transporter proteins. Particles of median size 146.3±18.7 nm, containing anti-malarial agents in corn starch were prepared for investigating: (a) whether the glucose moiety in starch targets RBC via hexose transporter(s), (b) whether there are differences in the extent of targeting to uninfected RBC versus infected RBC (iRBC) in view of higher cell surface density of these proteins on iRBC and (c) whether targeting provides enhanced efficacy against P. falciparum in comparison to drugs in solution. Binding of these particles to RBC was target-specific, since it could be blocked by phloretin, an inhibitor of glucose transporters (GLUT), or competed out in a dose-dependent manner with d-glucose in a flow cytometry assay. Significant (P=0.048, t-test) differences in extent of targeting to iRBC versus RBC were observed in flow cytometry. CDRI 97/63 incorporated in particles was 63% more efficacious than its solution at 250 ng/ml, while quinine was 20% more efficacious at 6.25 ng/ml in a SYBR Green incorporation assay. Preferential targeting of iRBC using an inexpensive excipient promises advantages in terms of dose reduction and toxicity alleviation. PMID:25666024

  14. 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

  15. A primate model for human cerebral malaria: Plasmodium coatneyi-infected rhesus monkeys.

    PubMed

    Aikawa, M; Brown, A; Smith, C D; Tegoshi, T; Howard, R J; Hasler, T H; Ito, Y; Perry, G; Collins, W E; Webster, K

    1992-04-01

    A major factor in the pathogenesis of human cerebral malaria is blockage of cerebral microvessels by the sequestration of parasitized human red blood cells (PRBC). In vitro studies indicate that sequestration of PRBC in the microvessels is mediated by the attachment of knobs on PRBC to receptors on the endothelial cell surface such as CD36, thrombospondin (TSP), and intercellular adhesion molecule-1 (ICAM-1). However, it is difficult to test this theory in vivo because fresh human brain tissues from cerebral malarial autopsy cases are not easy to obtain. Although several animal models for human cerebral malaria have been proposed, none have shown pathologic findings that are similar to those seen in humans. In order to develop an animal model for human cerebral malaria, we studied brains of rhesus monkeys infected with the primate malaria parasite, Plasmodium coatneyi. Our study demonstrated PRBC sequestration and cytoadherence of knobs on PRBC to endothelial cells in the cerebral microvessels of these monkeys. Cerebral microvessels with sequestered PRBC were shown by immunohistochemical analysis to possess CD36, TSP, and ICAM-1. These proteins were not evident in the cerebral microvessels of uninfected control monkeys. Thus, our study indicates, for the first time, that rhesus monkeys infected with P. coatneyi can be used as a primate model to study human cerebral malaria. By using this animal model, we may be able to evaluate strategies for the development of vaccines to prevent human cerebral malaria. PMID:1374220

  16. Risk factors for Plasmodium vivax infection in the Lacandon forest, southern Mexico.

    PubMed Central

    Danis-Lozano, R.; Rodriguez, M. H.; Gonzalez-Ceron, L.; Hernandez-Avila, M.

    1999-01-01

    A study was conducted to characterize the risk of Plasmodium vivax infection in the Lacandon forest, southern Mexico. Blood samples and questionnaire data were collected in 1992. Malaria cases (n = 137) were identified by the presence of symptoms and a positive thick blood smear. The control group included individuals with negative antibody titres and no history of malaria (n = 4994). From 7628 individuals studied, 1006 had anti-P. vivax antibodies. Seroprevalence increased with age. Risk factors associated with infection included: place of birth outside the village of residence (odds ratio, OR 11.67; 95% CI 5.21-26.11); no use of medical services (OR 4.69, 95% CI 3.01-7.29), never using bed-nets (OR 3.98, 95 % CI 1.23-12.86) and poor knowledge of malaria transmission, prevention and treatment (OR 2.30, 95 % CI 1.30-4.07). Health education represents the best recommendation for controlling the disease in the area. PMID:10459651

  17. Plasmodium vivax and Mansonella ozzardi co-infection in north-western Argentina

    PubMed Central

    2013-01-01

    A case of co-infection with Plasmodium vivax and Mansonella ozzardi was detected in a blood sample from a person who had shown symptoms of malaria and lived in a city that was close to the Argentina/Bolivia border. The case was detected during a random revision of thick and thin smears from patients diagnosed with malaria from various towns and cities located in north-western Argentina between 1983 and 2001. Trophozoites of P. vivax were observed in the thin blood smear along with M. ozzardi microfilaria (larval form), which presented a long, slender, pointed anucleate tail and the absence of the sheath. This last characteristic is shared with Mansonella perstans, Mansonella streptocerca and Onchocerca volvulus. More rigorously controlled studies to detect other co-infection cases in the area as well as the possibility of importation from Bolivia into Argentina are currently ongoing. The relationship between the malaria parasite and microfilaria, the potential effect of malaria treatment on the development of M. ozzardi, and the possible impact of this microfilaria on the immunity of a person against P. vivax are all still unknown. This contribution constitutes a point of focus for future studies involving the interaction between the parasites and the potential risk that humans are exposed to. PMID:23866313

  18. 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

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

    PubMed

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

    2013-02-01

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

  20. Antiplasmodial activity of Xanthium strumarium against Plasmodium berghei-infected BALB/c mice.

    PubMed

    Chandel, Sanjeev; Bagai, Upma; Vashishat, Nisha

    2012-03-01

    The present work was undertaken to evaluate the antiplasmodial activity of ethanolic leaves extract of traditional medicinal plant Xanthium strumarium in Plasmodium berghei-infected BALB/c mice along with phytochemical screening and acute toxicity test to support its traditional medicinal use as a malaria remedy. The ethanolic leaves extract of X. strumarium (ELEXS) 150, 250, 350 and 500 mg/kg/day demonstrated dose-dependent chemosuppression during early and established infection long with significant (p < 0.001) repository activity. The oral administration of 500 mg/kg/day concentration showed a maximum of 88.6% chemosuppression during early infection, which was more than that of the standard drug chloroquine (5 mg/kg/day) with 88.3% chemosuppression. However, 60% mortality has been found in this group. The LD(50) of ELEXS was found to be 1.5 g/kg/mouse. The administration of 350 mg/kg/day concentration of extract have been found to exert 90.40% chemosuppression during repository infection, which was well comparable to standard drug pyrimethamine (1.2 mg/kg/day) exerting 92.91% chemosuppression. The extract has been found to enhance mean survival time of mice from 21 to 26 days with 250 and 350 mg/kg/day concentrations, while 150 mg/kg/day concentration has been found to sustain all the mice up to 29 days which was similar to the employed standard drug chloroquine (5 mg/kg/day). All these findings support the ethanopharmacological use of X. strumarium as malarial remedy and indicate the potential of plant for active antiplasmodial components. PMID:21847597

  1. The Role of Reactive Oxygen Species in Anopheles aquasalis Response to Plasmodium vivax Infection

    PubMed Central

    Bahia, Ana C.; Oliveira, José Henrique M.; Kubota, Marina S.; Araújo, Helena R. C.; Lima, José B. P.; Ríos-Velásquez, Claudia Maria; Lacerda, Marcus Vinícius G.; Oliveira, Pedro L.

    2013-01-01

    Malaria affects millions of people worldwide and hundreds of thousands of people each year in Brazil. The mosquito Anopheles aquasalis is an important vector of Plasmodium vivax, the main human malaria parasite in the Americas. Reactive oxygen species (ROS) have been shown to have a role in insect innate immune responses as a potent pathogen-killing agent. We investigated the mechanisms of free radicals modulation after A. aquasalis infection with P. vivax. ROS metabolism was evaluated in the vector by studying expression and activity of three key detoxification enzymes, one catalase and two superoxide dismutases (SOD3A and SOD3B). Also, the involvement of free radicals in the mosquito immunity was measured by silencing the catalase gene followed by infection of A. aquasalis with P. vivax. Catalase, SOD3A and SOD3B expression in whole A. aquasalis were at the same levels of controls at 24 h and upregulated 36 h after ingestion of blood containing P. vivax. However, in the insect isolated midgut, the mRNA for these enzymes was not regulated by P. vivax infection, while catalase activity was reduced 24 h after the infectious meal. RNAi-mediated silencing of catalase reduced enzyme activity in the midgut, resulted in increased P. vivax infection and prevalence, and decreased bacterial load in the mosquito midgut. Our findings suggest that the interactions between A. aquasalis and P. vivax do not follow the model of ROS-induced parasite killing. It appears that P. vivax manipulates the mosquito detoxification system in order to allow its own development. This can be an indirect effect of fewer competitive bacteria present in the mosquito midgut caused by the increase of ROS after catalase silencing. These findings provide novel information on unique aspects of the main malaria parasite in the Americas interaction with one of its natural vectors. PMID:23441231

  2. Maturation of Plasmodium falciparum in multiply infected erythrocytes and the potential role in malaria pathogenesis.

    PubMed

    Orjih, Augustine U

    2014-11-01

    Erythrocytes containing two or more parasites, referred to here as multiply infected erythrocytes (MIEs), are common in the blood of humans infected by Plasmodium falciparum. It is necessary to study these cells closely because the excess numbers of parasites they contain suggest that they could be overloaded with virulence factors. Here, microscopic examinations of blood smears from patients showed that up to seven merozoites can successfully invade an erythrocyte and mature to ring stage. However, in vitro culture showed that only up to three parasites can mature to late schizont stage. These observations were made by culturing the parasites in erythrocytes containing hemoglobin AA (HbAA), HbAS, and HbSS. Biochemical analysis of saponin-concentrated culture suggests that more hemozoin is produced in a MIE than in a singly infected erythrocyte (SIE). Studies have shown that ingestion of excessive hemozoin destroys monocytes and neutrophils, which could impair the immune system. Cultured parasites were also examined by transmission electron microscopy, and it was found that the quantity of knobs was dramatically increased on the membranes of erythrocytes containing multiple schizonts, compared to those containing only one schizont. Knobs contain, among other things, P. falciparum erythrocyte membrane protein 1 (PfEMP1) complex which mediates sequestration and promotes severe malaria. These findings suggest that P. falciparum increases its virulence by producing MIEs. On sexual life cycle of the parasite, microphotographs are presented in this report showing, for the first time, that two gametocytes can develop in one erythrocyte; they are referred to here as twin gametocytes. It is not known whether they can infect mosquitoes. PMID:25120031

  3. Impact of repeated four-monthly anthelmintic treatment on Plasmodium infection in preschool children: a double-blind placebo-controlled randomized trial

    PubMed Central

    2010-01-01

    Background Helminth infections can alter susceptibility to malaria. Studies need to determine whether or not deworming programs can impact on Plasmodium infections in preschool children. Methods A double-blind placebo-controlled randomised trial was conducted to investigate the impact of anthelmintic treatment on Plasmodium infection in children aged 12-59 months. Children were randomly assigned to receive either albendazole or placebo every four months for 12 months with a follow-up at 14 months. Results 320 children (out of 1228, 26.1%) complied with all the follow-up assessments. Plasmodium prevalence and mean Plasmodium parasite density was significantly higher in the treatment group (44.9% and 2319 ± SE 511) compared to the placebo group (33.3% and 1471 ± 341) at baseline. The odds of having Plasmodium infection increased over time for children in both the placebo and treatment groups, however this increase was significantly slower for children in the treatment group (P = 0.002). By month 14, mean Plasmodium density had increased by 156% in the placebo group and 98% in the treatment group but the rate of change in Plasmodium density was not significantly different between the groups. The change from baseline in haemoglobin had a steeper increase among children in the treatment group when compared to the placebo group but this was not statistically significant. Conclusions Repeated four-monthly anthelminthic treatments for 14 months resulted in a significantly lower increase in the prevalence of Plasmodium infection in preschool children which coincided with a reduction in both the prevalence and intensity of A. lumbricoides infections. Trial Registration Current controlled trials ISRCTN44215995 PMID:20858280

  4. IFNγ and IL-12 Restrict Th2 Responses during Helminth/Plasmodium Co-Infection and Promote IFNγ from Th2 Cells

    PubMed Central

    Coomes, Stephanie M.; Pelly, Victoria S.; Kannan, Yashaswini; Okoye, Isobel S.; Czieso, Stephanie; Entwistle, Lewis J.; Perez-Lloret, Jimena; Nikolov, Nikolay; Potocnik, Alexandre J.; Biró, Judit; Langhorne, Jean; Wilson, Mark S.

    2015-01-01

    Parasitic helminths establish chronic infections in mammalian hosts. Helminth/Plasmodium co-infections occur frequently in endemic areas. However, it is unclear whether Plasmodium infections compromise anti-helminth immunity, contributing to the chronicity of infection. Immunity to Plasmodium or helminths requires divergent CD4+ T cell-driven responses, dominated by IFNγ or IL-4, respectively. Recent literature has indicated that Th cells, including Th2 cells, have phenotypic plasticity with the ability to produce non-lineage associated cytokines. Whether such plasticity occurs during co-infection is unclear. In this study, we observed reduced anti-helminth Th2 cell responses and compromised anti-helminth immunity during Heligmosomoides polygyrus and Plasmodium chabaudi co-infection. Using newly established triple cytokine reporter mice (Il4gfpIfngyfpIl17aFP635), we demonstrated that Il4gfp+ Th2 cells purified from in vitro cultures or isolated ex vivo from helminth-infected mice up-regulated IFNγ following adoptive transfer into Rag1–/– mice infected with P. chabaudi. Functionally, Th2 cells that up-regulated IFNγ were transcriptionally re-wired and protected recipient mice from high parasitemia. Mechanistically, TCR stimulation and responsiveness to IL-12 and IFNγ, but not type I IFN, was required for optimal IFNγ production by Th2 cells. Finally, blockade of IL-12 and IFNγ during co-infection partially preserved anti-helminth Th2 responses. In summary, this study demonstrates that Th2 cells retain substantial plasticity with the ability to produce IFNγ during Plasmodium infection. Consequently, co-infection with Plasmodium spp. may contribute to the chronicity of helminth infection by reducing anti-helminth Th2 cells and converting them into IFNγ-secreting cells. PMID:26147567

  5. Comparison of Imported Plasmodium ovale curtisi and P. ovale wallikeri Infections among Patients in Spain, 2005–2011

    PubMed Central

    Rubio-Muñoz, José Miguel; Ramírez-Olivencia, Germán; García-Bujalance, Silvia; Elcuaz-Romano, Rosa; Díaz-Menéndez, Marta; Calderón, María; García-Bermejo, Isabel; Ruiz-Giardín, José Manuel; Merino-Fernández, Francisco Jesús; Torrús-Tendero, Diego; Delgado-Iribarren, Alberto; Ribell-Bachs, Mónica; Arévalo-Serrano, Juan; Cuadros-González, Juan

    2014-01-01

    Sequencing data from Plasmodium ovale genotypes co-circulating in multiple countries support the hypothesis that P. ovale curtisi and P. ovale wallikeri are 2 separate species. We conducted a multicenter, retrospective, comparative study in Spain of 21 patients who had imported P. ovale curtisi infections and 14 who had imported P. ovale wallikeri infections confirmed by PCR and gene sequencing during June 2005–December 2011. The only significant finding was more severe thrombocytopenia among patients with P. ovale wallikeri infection than among those with P. ovale curtisi infection (p = 0.031). However, we also found nonsignificant trends showing that patients with P. ovale wallikeri infection had shorter time from arrival in Spain to onset of symptoms, lower level of albumin, higher median maximum core temperature, and more markers of hemolysis than did those with P. ovale curtisi infection. Larger, prospective studies are needed to confirm these findings. PMID:24572501

  6. Interaction between rifampicin, amodiaquine and artemether in mice infected with chloroquine resistant Plasmodium berghei

    PubMed Central

    2014-01-01

    Background Artemisinin-based combination therapy (ACT) remains the most effective chemotherapeutic strategy in the management of malaria. However, reports of reduced susceptibility of Plasmodium falciparum to the ACT justify the need for continued search for alternative anti-malarial drugs. The use of antibiotics with anti-malarial properties represents a potentially valuable chemotherapeutic option for the management of drug resistant infections. Thus, the intrinsic anti-malarial activity of the combination of clinical doses of rifampicin with amodiaquine and artemether was evaluated in an animal model using Plasmodium berghei. Methods A modification of the suppressive tests in vivo was employed. The anti-malarial activity of standard doses of amodiaquine (AQ) with or without artemether (ART) and combined with varying doses of rifampicin (RIF 15 mg/kg or RIF 30 mg/kg body weight) was evaluated in 40 mice sub-divided into eight groups and inoculated intraperitoneally with 1 × 107 red blood cells infected with chloroquine-resistant P. berghei ANKA strain. There were two control groups of animals, one group received amodiaquine alone while the other group received saline. Parasiticidal activity and survival of the animals were assessed over 21 days. Results Parasitaemia in the control animals peaked at 38% on day 9 and all animals died by day 10. The combination of amodiaquine with rifampicin 15 mg/kg body weight was the most effective of all the combinations and more efficacious than amodiaquine alone. The order of superiority of anti-malarial efficacy of the combinations was as follows; AQ + RIF 15 > AQ > AQ + ART + RIF 30 > AQ + ART + RIF 15 > AQ + RIF 30. Conclusion The combination of the clinical dose of rifampicin (15 mg/kg) with amodiaquine represents a potentially valuable treatment option in management of drug resistant malaria. In addition, the role of pharmacokinetic interaction in multiple drug therapy

  7. In Vivo Antimalarial Activity of Annona muricata Leaf Extract in Mice Infected with Plasmodium berghei

    PubMed Central

    Somsak, Voravuth; Polwiang, Natsuda; Chachiyo, Sukanya

    2016-01-01

    Malaria is one of the most important infectious diseases in the world. The choice for the treatment is highly limited due to drug resistance. Hence, finding the new compounds to treat malaria is urgently needed. The present study was attempted to evaluate the antimalarial activity of the Annona muricata aqueous leaf extract in Plasmodium berghei infected mice. Aqueous leaf extract of A. muricata was prepared and tested for acute toxicity in mice. For efficacy test in vivo, standard 4-day suppressive test was carried out. ICR mice were inoculated with 107 parasitized erythrocytes of P. berghei ANKA by intraperitoneal injection. The extracts (100, 500, and 1000 mg/kg) were then given orally by gavage once a day for 4 consecutive days. Parasitemia, percentage of inhibition, and packed cell volume were subsequently calculated. Chloroquine (10 mg/kg) was given to infected mice as positive control while untreated control was given only distilled water. It was found that A. muricata aqueous leaf extract at doses of 100, 500, and 1000 mg/kg resulted in dose dependent parasitemia inhibition of 38.03%, 75.25%, and 85.61%, respectively. Survival time was prolonged in infected mice treated with the extract. Moreover, no mortality to mice was observed with this extract up to a dose of 4000 mg/kg. In conclusion, the A. muricata aqueous leaf extract exerted significant antimalarial activity with no toxicity and prolonged survival time. Therefore, this extract might contain potential lead molecule for the development of a new drug for malaria treatment. PMID:27092277

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

    PubMed Central

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

    2016-01-01

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

  9. Mosquito Feeding Assays to Determine the Infectiousness of Naturally Infected Plasmodium falciparum Gametocyte Carriers

    PubMed Central

    Bousema, Teun; Dinglasan, Rhoel R.; Morlais, Isabelle; Gouagna, Louis C.; van Warmerdam, Travis; Awono-Ambene, Parfait H.; Bonnet, Sarah; Diallo, Mouctar; Coulibaly, Mamadou; Tchuinkam, Timoléon; Mulder, Bert; Targett, Geoff; Drakeley, Chris; Sutherland, Colin; Robert, Vincent; Doumbo, Ogobara; Touré, Yeya; Graves, Patricia M.; Roeffen, Will; Sauerwein, Robert; Birkett, Ashley; Locke, Emily; Morin, Merribeth; Wu, Yimin; Churcher, Thomas S.

    2012-01-01

    Introduction In the era of malaria elimination and eradication, drug-based and vaccine-based approaches to reduce malaria transmission are receiving greater attention. Such interventions require assays that reliably measure the transmission of Plasmodium from humans to Anopheles mosquitoes. Methods We compared two commonly used mosquito feeding assay procedures: direct skin feeding assays and membrane feeding assays. Three conditions under which membrane feeding assays are performed were examined: assays with i) whole blood, ii) blood pellets resuspended with autologous plasma of the gametocyte carrier, and iii) blood pellets resuspended with heterologous control serum. Results 930 transmission experiments from Cameroon, The Gambia, Mali and Senegal were included in the analyses. Direct skin feeding assays resulted in higher mosquito infection rates compared to membrane feeding assays (odds ratio 2.39, 95% confidence interval 1.94–2.95) with evident heterogeneity between studies. Mosquito infection rates in membrane feeding assays and direct skin feeding assays were strongly correlated (p<0.0001). Replacing the plasma of the gametocyte donor with malaria naïve control serum resulted in higher mosquito infection rates compared to own plasma (OR 1.92, 95% CI 1.68–2.19) while the infectiousness of gametocytes may be reduced during the replacement procedure (OR 0.60, 95% CI 0.52–0.70). Conclusions Despite a higher efficiency of direct skin feeding assays, membrane feeding assays appear suitable tools to compare the infectiousness between individuals and to evaluate transmission-reducing interventions. Several aspects of membrane feeding procedures currently lack standardization; this variability makes comparisons between laboratories challenging and should be addressed to facilitate future testing of transmission-reducing interventions. PMID:22936993

  10. Genetic diversity and multiplicity of infection of Plasmodium falciparum isolates from Kolkata, West Bengal, India.

    PubMed

    Saha, Pabitra; Ganguly, Swagata; Maji, Ardhendu K

    2016-09-01

    The study of genetic diversity of Plasmodium falciparum is necessary to understand the distribution and dynamics of parasite populations. The genetic diversity of P. falciparum merozoite surface protein-1 and 2 has been extensively studied from different parts of world. However, limited data are available from India. This study was aimed to determine the genetic diversity and multiplicity of infection (MOI) of P. falciparum population in Kolkata, West Bengal, India. A total of 80day-zero blood samples from Kolkata were collected during a therapeutic efficacy study in 2008-2009. DNA was extracted; allelic frequency and diversity were investigated by PCR-genotyping method for msp1 and msp2 gene and fragment sizing was done by Bio-Rad Gel-Doc system using Image Lab (version 4.1) software. P. falciparum msp1 and msp2 markers were highly polymorphic with low allele frequencies. In Kolkata, 27 msp1 different genotypes (including 11of K1, 6 of MAD20 and 10 of Ro33 allelic families) and 30 different msp2 genotypes (of which 17 and 13 belonged to the FC27 and 3D7 allelic families, respectively) were recorded. The majority of these genotypes occurred at a frequency below 10%. The mean MOI for msp1 and msp2 gene were 2.05 and 3.72, respectively. The P. falciparum population of Kolkata was genetically diverse. As the frequencies of most of the msp1 and msp2 alleles were low, the probability of new infection with genotype identical to that in pretreatment infection was very rare. This information will serve as baseline data for evaluation of malaria control interventions as well as for monitoring the parasite population structure. PMID:27259367

  11. In Vivo Antimalarial Activity of Annona muricata Leaf Extract in Mice Infected with Plasmodium berghei.

    PubMed

    Somsak, Voravuth; Polwiang, Natsuda; Chachiyo, Sukanya

    2016-01-01

    Malaria is one of the most important infectious diseases in the world. The choice for the treatment is highly limited due to drug resistance. Hence, finding the new compounds to treat malaria is urgently needed. The present study was attempted to evaluate the antimalarial activity of the Annona muricata aqueous leaf extract in Plasmodium berghei infected mice. Aqueous leaf extract of A. muricata was prepared and tested for acute toxicity in mice. For efficacy test in vivo, standard 4-day suppressive test was carried out. ICR mice were inoculated with 10(7) parasitized erythrocytes of P. berghei ANKA by intraperitoneal injection. The extracts (100, 500, and 1000 mg/kg) were then given orally by gavage once a day for 4 consecutive days. Parasitemia, percentage of inhibition, and packed cell volume were subsequently calculated. Chloroquine (10 mg/kg) was given to infected mice as positive control while untreated control was given only distilled water. It was found that A. muricata aqueous leaf extract at doses of 100, 500, and 1000 mg/kg resulted in dose dependent parasitemia inhibition of 38.03%, 75.25%, and 85.61%, respectively. Survival time was prolonged in infected mice treated with the extract. Moreover, no mortality to mice was observed with this extract up to a dose of 4000 mg/kg. In conclusion, the A. muricata aqueous leaf extract exerted significant antimalarial activity with no toxicity and prolonged survival time. Therefore, this extract might contain potential lead molecule for the development of a new drug for malaria treatment. PMID:27092277

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

    PubMed Central

    2013-01-01

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

  13. Efficacy and Pharmacokinetics of Intravenous Nanocapsule Formulations of Halofantrine in Plasmodium berghei-Infected Mice

    PubMed Central

    Mosqueira, Vanessa C. F.; Loiseau, Philippe M.; Bories, Christian; Legrand, Philippe; Devissaguet, Jean-Philippe; Barratt, Gillian

    2004-01-01

    The efficacy and pharmacokinetics of a new parenteral formulation of halofantrine were studied in mice infected with Plasmodium berghei. The formulation consisted of nanocapsules with an oily core, prepared from either poly(d,l-lactide) (PLA) homopolymer or PLA that was surface modified with grafted polyethylene glycol chains. They were compared with a previously described intravenous halofantrine preparation. No toxic effects were observed with halofantrine in form of nanocapsules after intravenous administration for doses of up to 100 mg/kg, whereas the solubilized form in polyethylene glycol-dimethylacetamide was toxic at this dose. The halofantrine-loaded nanocapsules showed activity that was similar to or better than that of the solution in the 4-day test and as a single dose in severely infected mice, with only minimal differences between the two nanocapsule formulations. Halofantrine pharmacokinetics were determined in parallel with parasite development in severely infected mice. Nanocapsules increased the area under the curve for halofantrine in plasma more than sixfold compared with the solution throughout the experimental period of 70 h. Furthermore, nanocapsules induced a significantly faster control of parasite development than the solution in the first 48 h posttreatment. While the parasitemia fell more rapidly with PLA nanocapsules, the effect was more sustained with the surface-modified ones. This is consistent with surface-modified nanocapsules remaining longer in the circulation. These results suggest that nanocapsule formulations could provide a more favorable halofantrine profile in the plasma and reduce the intravenous dose necessary and therefore the toxicity, thus suggesting the use of halofantrine by a parenteral route in severe malaria. PMID:15047523

  14. Efficacy and pharmacokinetics of intravenous nanocapsule formulations of halofantrine in Plasmodium berghei-infected mice.

    PubMed

    Mosqueira, Vanessa C F; Loiseau, Philippe M; Bories, Christian; Legrand, Philippe; Devissaguet, Jean-Philippe; Barratt, Gillian

    2004-04-01

    The efficacy and pharmacokinetics of a new parenteral formulation of halofantrine were studied in mice infected with Plasmodium berghei. The formulation consisted of nanocapsules with an oily core, prepared from either poly(D,L-lactide) (PLA) homopolymer or PLA that was surface modified with grafted polyethylene glycol chains. They were compared with a previously described intravenous halofantrine preparation. No toxic effects were observed with halofantrine in form of nanocapsules after intravenous administration for doses of up to 100 mg/kg, whereas the solubilized form in polyethylene glycol-dimethylacetamide was toxic at this dose. The halofantrine-loaded nanocapsules showed activity that was similar to or better than that of the solution in the 4-day test and as a single dose in severely infected mice, with only minimal differences between the two nanocapsule formulations. Halofantrine pharmacokinetics were determined in parallel with parasite development in severely infected mice. Nanocapsules increased the area under the curve for halofantrine in plasma more than sixfold compared with the solution throughout the experimental period of 70 h. Furthermore, nanocapsules induced a significantly faster control of parasite development than the solution in the first 48 h posttreatment. While the parasitemia fell more rapidly with PLA nanocapsules, the effect was more sustained with the surface-modified ones. This is consistent with surface-modified nanocapsules remaining longer in the circulation. These results suggest that nanocapsule formulations could provide a more favorable halofantrine profile in the plasma and reduce the intravenous dose necessary and therefore the toxicity, thus suggesting the use of halofantrine by a parenteral route in severe malaria. PMID:15047523

  15. A spiral scaffold underlies cytoadherent knobs in Plasmodium falciparum-infected erythrocytes.

    PubMed

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

    2016-01-21

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

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

    PubMed Central

    2013-01-01

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

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

    PubMed

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

    2016-10-01

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

  18. CD47-SIRPα Interactions Regulate Macrophage Uptake of Plasmodium falciparum-Infected Erythrocytes and Clearance of Malaria In Vivo.

    PubMed

    Ayi, Kodjo; Lu, Ziyue; Serghides, Lena; Ho, Jenny M; Finney, Constance; Wang, Jean C Y; Liles, W Conrad; Kain, Kevin C

    2016-07-01

    CD47 engagement by the macrophage signal regulatory protein alpha (SIRPα) inhibits phagocytic activity and protects red blood cells (RBCs) from erythrophagocytosis. The role of CD47-SIRPα in the innate immune response to Plasmodium falciparum infection is unknown. We hypothesized that disruption of SIRPα signaling may enhance macrophage uptake of malaria parasite-infected RBCs. To test this hypothesis, we examined in vivo clearance in CD47-deficient mice infected with Plasmodium berghei ANKA and in vitro phagocytosis of P. falciparum-infected RBCs by macrophages from SHP-1-deficient (Shp-1(-/-)) mice and NOD.NOR-Idd13.Prkdc(scid) (NS-Idd13) mice, as well as human macrophages, following disruption of CD47-SIRPα interactions with anti-SIRPα antibodies or recombinant SIRPα-Fc fusion protein. Compared to their wild-type counterparts, Cd47(-/-) mice displayed significantly lower parasitemia, decreased endothelial activation, and enhanced survival. Using macrophages from SHP-1-deficient mice or from NS-Idd13 mice, which express a SIRPα variant that does not bind human CD47, we showed that altered SIRPα signaling resulted in enhanced phagocytosis of P. falciparum-infected RBCs. Moreover, disrupting CD47-SIRPα engagement using anti-SIRPα antibodies or SIRPα-Fc fusion protein also increased phagocytosis of P. falciparum-infected RBCs. These results indicate an important role for CD47-SIRPα interactions in innate control of malaria and suggest novel targets for intervention. PMID:27091932

  19. Defining the relationship between infection prevalence and clinical incidence of Plasmodium falciparum malaria.

    PubMed

    Cameron, Ewan; Battle, Katherine E; Bhatt, Samir; Weiss, Daniel J; Bisanzio, Donal; Mappin, Bonnie; Dalrymple, Ursula; Hay, Simon I; Smith, David L; Griffin, Jamie T; Wenger, Edward A; Eckhoff, Philip A; Smith, Thomas A; Penny, Melissa A; Gething, Peter W

    2015-01-01

    In many countries health system data remain too weak to accurately enumerate Plasmodium falciparum malaria cases. In response, cartographic approaches have been developed that link maps of infection prevalence with mathematical relationships to predict the incidence rate of clinical malaria. Microsimulation (or 'agent-based') models represent a powerful new paradigm for defining such relationships; however, differences in model structure and calibration data mean that no consensus yet exists on the optimal form for use in disease-burden estimation. Here we develop a Bayesian statistical procedure combining functional regression-based model emulation with Markov Chain Monte Carlo sampling to calibrate three selected microsimulation models against a purpose-built data set of age-structured prevalence and incidence counts. This allows the generation of ensemble forecasts of the prevalence-incidence relationship stratified by age, transmission seasonality, treatment level and exposure history, from which we predict accelerating returns on investments in large-scale intervention campaigns as transmission and prevalence are progressively reduced. PMID:26348689

  20. CD40 is required for protective immunity against liver stage Plasmodium infection1

    PubMed Central

    Murray, Sara A; Mohar, Isaac; Miller, Jessica L; Brempelis, Katherine J; Vaughan, Ashley M; Kappe, Stefan HI; Crispe, Ian N

    2015-01-01

    The co-stimulatory molecule CD40 enhances immunity through several distinct roles in T cell activation and T cell interaction with other immune cells. In a mouse model of immunity to liver stage Plasmodium infection, CD40 was critical for the full maturation of liver dendritic cells, accumulation of CD8+ T cells in the liver, and protective immunity induced by immunization with the P. yoelii fabb/f- genetically attenuated parasite. Using mixed adoptive transfers of polyclonal wild type (WT) and CD40-deficient (CD40−/−) CD8+ T cells into WT and CD40−/− hosts, we evaluated the contributions to CD8+ T cell immunity of CD40 expressed on host tissues including antigen-presenting cells (APC), compared to CD40 expressed on the CD8+ T cells themselves. Most of the effects of CD40 could be accounted for by expression in the T cells’ environment, including the accumulation of large numbers of CD8+ T cells in the livers of immunized mice. Thus, protective immunity generated during immunization with fabb/f- was largely dependent on effective APC licensing via CD40 signaling. PMID:25646303

  1. Defining the morphology and mechanism of the hemoglobin transport pathway in Plasmodium falciparum-infected erythrocytes.

    PubMed

    Milani, Katharine J; Schneider, Timothy G; Taraschi, Theodore F

    2015-04-01

    Hemoglobin degradation during the asexual cycle of Plasmodium falciparum is an obligate process for parasite development and survival. It is established that hemoglobin is transported from the host erythrocyte to the parasite digestive vacuole (DV), but this biological process is not well characterized. Three-dimensional reconstructions made from serial thin-section electron micrographs of untreated, trophozoite-stage P. falciparum-infected erythrocytes (IRBC) or IRBC treated with different pharmacological agents provide new insight into the organization and regulation of the hemoglobin transport pathway. Hemoglobin internalization commences with the formation of cytostomes from localized, electron-dense collars at the interface of the parasite plasma and parasitophorous vacuolar membranes. The cytostomal collar does not function as a site of vesicle fission but rather serves to stabilize the maturing cytostome. We provide the first evidence that hemoglobin transport to the DV uses an actin-myosin motor system. Short-lived, hemoglobin-filled vesicles form from the distal end of the cytostomes through actin and dynamin-mediated processes. Results obtained with IRBC treated with N-ethylmaleimide (NEM) suggest that fusion of hemoglobin-containing vesicles with the DV may involve a soluble NEM-sensitive factor attachment protein receptor-dependent mechanism. In this report, we identify new key components of the hemoglobin transport pathway and provide a detailed characterization of its morphological organization and regulation. PMID:25724884

  2. 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

  3. Defining the relationship between infection prevalence and clinical incidence of Plasmodium falciparum malaria

    PubMed Central

    Cameron, Ewan; Battle, Katherine E.; Bhatt, Samir; Weiss, Daniel J.; Bisanzio, Donal; Mappin, Bonnie; Dalrymple, Ursula; Hay, Simon I.; Smith, David L.; Griffin, Jamie T.; Wenger, Edward A.; Eckhoff, Philip A.; Smith, Thomas A.; Penny, Melissa A.; Gething, Peter W.

    2015-01-01

    In many countries health system data remain too weak to accurately enumerate Plasmodium falciparum malaria cases. In response, cartographic approaches have been developed that link maps of infection prevalence with mathematical relationships to predict the incidence rate of clinical malaria. Microsimulation (or ‘agent-based') models represent a powerful new paradigm for defining such relationships; however, differences in model structure and calibration data mean that no consensus yet exists on the optimal form for use in disease-burden estimation. Here we develop a Bayesian statistical procedure combining functional regression-based model emulation with Markov Chain Monte Carlo sampling to calibrate three selected microsimulation models against a purpose-built data set of age-structured prevalence and incidence counts. This allows the generation of ensemble forecasts of the prevalence–incidence relationship stratified by age, transmission seasonality, treatment level and exposure history, from which we predict accelerating returns on investments in large-scale intervention campaigns as transmission and prevalence are progressively reduced. PMID:26348689

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

    PubMed

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

    2011-09-01

    The cellular events leading to severe and complicated malaria in some Plasmodium falciparum infections are poorly understood. Additional tools are required to better understand the pathogenesis of this disease. In this technical report, we describe a microfluidic culture system and image processing algorithms that were developed to observe cytoadhesion interactions of P. falciparum parasitized erythrocytes rolling on primary brain microvascularendothelial cells. We isolated and cultured human primary microvascular brain endothelial cells in a closed loop microfluidic culture system where a peristaltic pump and media reservoirs were integrated onto a microscope stage insert. We developed image processing methods to enhance contrast of rolling parasitized erythrocytes on endothelial cells and to estimate the local wall shear stress. The velocity of parasitized erythrocytes rolling on primary brain microvascularendothelial cells was then measured under physiologically relevant wall shear stresses. Finally, we deployed this method successfully at a field site in Blantyre, Malawi. The method is a promising new tool for the investigation of the pathogenesis of severe malaria. PMID:21743938

  5. Impaired cytoadherence of Plasmodium falciparum-infected erythrocytes containing sickle hemoglobin

    PubMed Central

    Cholera, Rushina; Brittain, Nathaniel J.; Gillrie, Mark R.; Lopera-Mesa, Tatiana M.; Diakité, Séidina A. S.; Arie, Takayuki; Krause, Michael A.; Guindo, Aldiouma; Tubman, Abby; Fujioka, Hisashi; Diallo, Dapa A.; Doumbo, Ogobara K.; Ho, May; Wellems, Thomas E.; Fairhurst, Rick M.

    2008-01-01

    Sickle trait, the heterozygous state of normal hemoglobin A (HbA) and sickle hemoglobin S (HbS), confers protection against malaria in Africa. AS children infected with Plasmodium falciparum are less likely than AA children to suffer the symptoms or severe manifestations of malaria, and they often carry lower parasite densities than AA children. The mechanisms by which sickle trait might confer such malaria protection remain unclear. We have compared the cytoadherence properties of parasitized AS and AA erythrocytes, because it is by these properties that parasitized erythrocytes can sequester in postcapillary microvessels of critical tissues such as the brain and cause the life-threatening complications of malaria. Our results show that the binding of parasitized AS erythrocytes to microvascular endothelial cells and blood monocytes is significantly reduced relative to the binding of parasitized AA erythrocytes. Reduced binding correlates with the altered display of P. falciparum erythrocyte membrane protein-1 (PfEMP-1), the parasite's major cytoadherence ligand and virulence factor on the erythrocyte surface. These findings identify a mechanism of protection for HbS that has features in common with that of hemoglobin C (HbC). Coinherited hemoglobin polymorphisms and naturally acquired antibodies to PfEMP-1 may influence the degree of malaria protection in AS children by further weakening cytoadherence interactions. PMID:18192399

  6. Genetic characterization of Hawaiian isolates of Plasmodium relictum reveals mixed-genotype infections

    USGS Publications Warehouse

    Jarvi, S.I.; Farias, M.E.M.; Atkinson, C.T.

    2008-01-01

    Background: The relatively recent introduction of a highly efficient mosquito vector and an avian pathogen (Plasmodium relictum) to an isolated island ecosystem with nai??ve, highly susceptible avian hosts provides a unique opportunity to investigate evolution of virulence in a natural system. Mixed infections can significantly contribute to the uncertainty in host-pathogen dynamics with direct impacts on virulence. Toward further understanding of how host-parasite and parasite-parasite relationships may impact virulence, this study characterizes within-host diversity of malaria parasite populations based on genetic analysis of the trap (thrombospondin-related anonymous protein) gene in isolates originating from Hawaii, Maui and Kauai Islands. Methods: A total of 397 clones were produced by nested PCR amplification and cloning of a 1664 bp fragment of the trap gene from two malarial isolates, K1 (Kauai) and KV115 (Hawaii) that have been used for experimental studies, and from additional isolates from wild birds on Kauai, Maui and Hawaii Islands. Diversity of clones was evaluated initially by RFLP-based screening, followed by complete sequencing of 33 selected clones. Results: RFLP analysis of trap revealed a minimum of 28 distinct RFLP haplotypes among the 397 clones from 18 birds. Multiple trap haplotypes were detected in every bird evaluated, with an average of 5.9 haplotypes per bird. Overall diversity did not differ between the experimental isolates, however, a greater number of unique haplotypes were detected in K1 than in KV115. We detected high levels of clonal diversity with clear delineation between isolates K1 and KV115 in a haplotype network. The patterns of within-host haplotype clustering are consistent with the possibility of a clonal genetic structure and rapid within-host mutation after infection. Conclusion: Avian malaria (P. relictum) and Avipoxvirus are the significant infectious diseases currently affecting the native Hawaiian avifauna. This

  7. Genetic characterization of Hawaiian isolates of Plasmodium relictum reveals mixed-genotype infections

    PubMed Central

    Jarvi, Susan I; Farias, Margaret EM; Atkinson, Carter T

    2008-01-01

    Background The relatively recent introduction of a highly efficient mosquito vector and an avian pathogen (Plasmodium relictum) to an isolated island ecosystem with naïve, highly susceptible avian hosts provides a unique opportunity to investigate evolution of virulence in a natural system. Mixed infections can significantly contribute to the uncertainty in host-pathogen dynamics with direct impacts on virulence. Toward further understanding of how host-parasite and parasite-parasite relationships may impact virulence, this study characterizes within-host diversity of malaria parasite populations based on genetic analysis of the trap (thrombospondin-related anonymous protein) gene in isolates originating from Hawaii, Maui and Kauai Islands. Methods A total of 397 clones were produced by nested PCR amplification and cloning of a 1664 bp fragment of the trap gene from two malarial isolates, K1 (Kauai) and KV115 (Hawaii) that have been used for experimental studies, and from additional isolates from wild birds on Kauai, Maui and Hawaii Islands. Diversity of clones was evaluated initially by RFLP-based screening, followed by complete sequencing of 33 selected clones. Results RFLP analysis of trap revealed a minimum of 28 distinct RFLP haplotypes among the 397 clones from 18 birds. Multiple trap haplotypes were detected in every bird evaluated, with an average of 5.9 haplotypes per bird. Overall diversity did not differ between the experimental isolates, however, a greater number of unique haplotypes were detected in K1 than in KV115. We detected high levels of clonal diversity with clear delineation between isolates K1 and KV115 in a haplotype network. The patterns of within-host haplotype clustering are consistent with the possibility of a clonal genetic structure and rapid within-host mutation after infection. Conclusion Avian malaria (P. relictum) and Avipoxvirus are the significant infectious diseases currently affecting the native Hawaiian avifauna. This study

  8. Regular production of infective sporozoites of Plasmodium falciparum and P. vivax in laboratory-bred Anopheles albimanus.

    PubMed

    Hurtado, S; Salas, M L; Romero, J F; Zapata, J C; Ortiz, H; Arevalo-Herrera, M; Herrera, S

    1997-01-01

    One of the major constraints for studies on the sporogonic cycle of the parasites causing human malaria, and on the protective efficacy of pre-erythrocytic vaccines, is the scarcity of laboratory-reared Anopheles mosquitoes as a source of infective sporozoites. The aim of the present study was to reproduce the life-cycles of Plasmodium falciparum and P. vivax in the laboratory and so develop the ability to produce infective sporozoites of these two species regularly under laboratory conditions. Colonized Anopheles albimanus, of Buenaventura and Tecojate strains, were infected by feeding either on Plasmodium-infected blood, from human patients or experimentally inoculated Aotus monkeys, or on gametocytes of the P. falciparum NF-54 isolate grown in vitro. The monkeys were infected with the blood stages of a Colombian P. vivax isolate and then, after recovery, with the Santa Lucia strain of P. falciparum from El Salvador. Although both of the mosquito strains used were successfully infected with both parasite species, the Buenaventura strain of mosquito was generally more susceptible to infection than the Tecojate strain, and particularly to infection with the parasites from the patients, who lived where this strain of mosquitoes was originally isolated. Monkeys injected intravenously with the P. vivax sporozoites produced in the mosquitoes developed patent sexual and asexual parasitaemias; the gametocytes that developed could then be used to infect mosquitoes, allowing the development of more sporozoites. However, experimental infections failed to establish after the P. falciparum sporozoites were used to inoculate monkeys. The ability to reproduce the complete life cycle of P. vivax in the laboratory, from human to mosquito and then to monkey, should greatly facilitate many studies on vivax malaria and on the efficacy of candidate malaria vaccines. The availability of the sporogonic cycles of P. falciparum from three different sources should also permit a variety of

  9. Allelic family-specific humoral responses to merozoite surface protein 2 (MSP2) in Gabonese residents with Plasmodium falciparum infections

    PubMed Central

    EKALA, M-T; JOUIN, H; LEKOULOU, F; MERCEREAU-PUIJALON, O; NTOUMI, F

    2002-01-01

    Merozoite surface protein 2 (MSP2) expressed by Plasmodium falciparum asexual blood stages has been identified as a promising vaccine candidate. In order to explore allelic family-specific humoral responses which may be responsible for parasite neutralization during natural infections, isolates from individuals with either asymptomatic infections or uncomplicated malaria and residing in a Central African area where Plasmodium transmission is high and perennial, were analysed using MSP2 as polymorphic marker. The family-specific antibody responses were assessed by ELISA using MSP2 synthetic peptides. We observed an age-dependence of P. falciparum infection complexity. The decrease of infection complexity around 15 years of age was observed simultaneously with an increase in the mean number of MSP2 variants recognized. No significant difference in the P. falciparum genetic diversity and infection complexity was found in isolates from asymptomatic subjects and patients with uncomplicated malaria. The longitudinal follow-up showed a rapid development of immune responses to various regions of MSP2 variants within one week. Comparing humoral responses obtained with the other major antigen on the merozoite surface, MSP1, our findings suggest that different pathways of responsiveness are involved in antibody production to merozoite surface antigens. PMID:12165090

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

    PubMed Central

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

    2015-01-01

    With support from the Global Fund, the United States President's Malaria Initiative (PMI) and other cooperating partners, Malawi is implementing a comprehensive malaria control programme involving indoor residual spraying in targeted districts, universal coverage with insecticide-treated bed nets, use of rapid diagnostic tests to confirm the clinical diagnosis of malaria and use of the highly effective artemisinin-based combination therapy, artemether-lumefantrine (AL), as the first-line treatment for malaria. We genotyped 24 genome-wide single nucleotide polymorphisms (SNPs) in Plasmodium falciparum infections (n = 316) sampled from a single location in Malawi before (2006 and 2007) and after enhanced intervention (2008 and 2012). The SNP data generated were used to examine temporal changes in the proportion of multiple-genotype infections (MIs), mean number of heterozygous SNPs within MIs, parasite genetic diversity (expected heterozygosity and genotypic richness), multilocus linkage disequilibrium and effective population size (Ne). While the proportion of MIs, expected heterozygosity, genotypic richness, multilocus linkage disequilibrium and Ne were unchanged over time, the mean number (±standard deviation) of heterozygous SNPs within MIs decreased significantly (p = 0.01) from 9(±1) in 2006 to 7(±1) in 2012. These findings indicate that the genetic diversity of P. falciparum malaria parasites in this area remains high, suggesting that only subtle gains, if any, have been made in reducing malaria transmission. Continued surveillance is required to evaluate the impact of malaria control interventions in this area and the rest of Malawi, and to better target control interventions. PMID:25460345

  11. Immunization with the MAEBL M2 Domain Protects against Lethal Plasmodium yoelii Infection

    PubMed Central

    Leite, Juliana A.; Bargieri, Daniel Y.; Carvalho, Bruna O.; Albrecht, Letusa; Lopes, Stefanie C. P.; Kayano, Ana Carolina A. V.; Farias, Alessandro S.; Chia, Wan Ni; Claser, Carla; Malleret, Benoit; Russell, Bruce; Castiñeiras, Catarina; Santos, Leonilda M. B.; Brocchi, Marcelo; Wunderlich, Gerhard; Soares, Irene S.; Rodrigues, Mauricio M.; Rénia, Laurent

    2015-01-01

    Malaria remains a world-threatening disease largely because of the lack of a long-lasting and fully effective vaccine. MAEBL is a type 1 transmembrane molecule with a chimeric cysteine-rich ectodomain homologous to regions of the Duffy binding-like erythrocyte binding protein and apical membrane antigen 1 (AMA1) antigens. Although MAEBL does not appear to be essential for the survival of blood-stage forms, ectodomains M1 and M2, homologous to AMA1, seem to be involved in parasite attachment to erythrocytes, especially M2. MAEBL is necessary for sporozoite infection of mosquito salivary glands and is expressed in liver stages. Here, the Plasmodium yoelii MAEBL-M2 domain was expressed in a prokaryotic vector. C57BL/6J mice were immunized with doses of P. yoelii recombinant protein rPyM2-MAEBL. High levels of antibodies, with balanced IgG1 and IgG2c subclasses, were achieved. rPyM2-MAEBL antisera were capable of recognizing the native antigen. Anti-MAEBL antibodies recognized different MAEBL fragments expressed in CHO cells, showing stronger IgM and IgG responses to the M2 domain and repeat region, respectively. After a challenge with P. yoelii YM (lethal strain)-infected erythrocytes (IE), up to 90% of the immunized animals survived and a reduction of parasitemia was observed. Moreover, splenocytes harvested from immunized animals proliferated in a dose-dependent manner in the presence of rPyM2-MAEBL. Protection was highly dependent on CD4+, but not CD8+, T cells toward Th1. rPyM2-MAEBL antisera were also able to significantly inhibit parasite development, as observed in ex vivo P. yoelii erythrocyte invasion assays. Collectively, these findings support the use of MAEBL as a vaccine candidate and open perspectives to understand the mechanisms involved in protection. PMID:26169268

  12. The Plasmodium falciparum STEVOR Multigene Family Mediates Antigenic Variation of the Infected Erythrocyte

    PubMed Central

    Niang, Makhtar; Yan Yam, Xue; Preiser, Peter Rainer

    2009-01-01

    Modifications of the Plasmodium falciparum–infected red blood cell (iRBC) surface have been linked to parasite-associated pathology. Such modifications enable the parasite to establish long-lasting chronic infection by evading antibody mediate immune recognition and splenic clearance. With the exception of the well-demonstrated roles of var-encoded PfEMP1 in virulence and immune evasion, the biological significance of other variant surface antigens (rif and stevor) is largely unknown. While PfEMP1 and RIFIN have been located on the iRBC surface, recent studies have located STEVOR at the iRBC membrane where it may be exposed on the erythrocyte surface. To investigate the role of STEVOR in more detail, we have developed antibodies against two putative STEVOR proteins and used a combination of indirect immunofluorescence assays (IFA), live IFA, flow cytometry, as well as agglutination assays, which enable us to demonstrate that STEVOR is clonally variant at the surface of schizont stage parasites. Crucially, expression of different STEVOR on the surface of the iRBC changes the antigenic property of the parasite. Taken together, our data for the first time demonstrate that STEVOR plays a role in creating antigenic diversity of schizont stage parasites, thereby adding additional complexity to the immunogenic properties of the iRBC. Furthermore, it clearly demonstrates that to obtain a complete understanding of how parasite-induced pathology is linked to variation on the surface of the iRBC, focusing the interactions of multiple multigene families needs to be considered. PMID:19229319

  13. Immunization with the MAEBL M2 Domain Protects against Lethal Plasmodium yoelii Infection.

    PubMed

    Leite, Juliana A; Bargieri, Daniel Y; Carvalho, Bruna O; Albrecht, Letusa; Lopes, Stefanie C P; Kayano, Ana Carolina A V; Farias, Alessandro S; Chia, Wan Ni; Claser, Carla; Malleret, Benoit; Russell, Bruce; Castiñeiras, Catarina; Santos, Leonilda M B; Brocchi, Marcelo; Wunderlich, Gerhard; Soares, Irene S; Rodrigues, Mauricio M; Rénia, Laurent; Costa, Fabio T M

    2015-10-01

    Malaria remains a world-threatening disease largely because of the lack of a long-lasting and fully effective vaccine. MAEBL is a type 1 transmembrane molecule with a chimeric cysteine-rich ectodomain homologous to regions of the Duffy binding-like erythrocyte binding protein and apical membrane antigen 1 (AMA1) antigens. Although MAEBL does not appear to be essential for the survival of blood-stage forms, ectodomains M1 and M2, homologous to AMA1, seem to be involved in parasite attachment to erythrocytes, especially M2. MAEBL is necessary for sporozoite infection of mosquito salivary glands and is expressed in liver stages. Here, the Plasmodium yoelii MAEBL-M2 domain was expressed in a prokaryotic vector. C57BL/6J mice were immunized with doses of P. yoelii recombinant protein rPyM2-MAEBL. High levels of antibodies, with balanced IgG1 and IgG2c subclasses, were achieved. rPyM2-MAEBL antisera were capable of recognizing the native antigen. Anti-MAEBL antibodies recognized different MAEBL fragments expressed in CHO cells, showing stronger IgM and IgG responses to the M2 domain and repeat region, respectively. After a challenge with P. yoelii YM (lethal strain)-infected erythrocytes (IE), up to 90% of the immunized animals survived and a reduction of parasitemia was observed. Moreover, splenocytes harvested from immunized animals proliferated in a dose-dependent manner in the presence of rPyM2-MAEBL. Protection was highly dependent on CD4(+), but not CD8(+), T cells toward Th1. rPyM2-MAEBL antisera were also able to significantly inhibit parasite development, as observed in ex vivo P. yoelii erythrocyte invasion assays. Collectively, these findings support the use of MAEBL as a vaccine candidate and open perspectives to understand the mechanisms involved in protection. PMID:26169268

  14. Evaluation of the ex vivo antimalarial activity of organotin (IV) ethylphenyldithiocarbamate on erythrocytes infected with Plasmodium berghei NK 65.

    PubMed

    Awang, Normah; Jumat, Hafizah; Ishak, Shafariatul Akmar; Kamaludin, Nurul Farahana

    2014-06-01

    Malaria is the most destructive and dangerous parasitic disease. The commonness of this disease is getting worse mainly due to the increasing resistance of Plasmodium falciparum against antimalarial drugs. Therefore, the search for new antimalarial drug is urgently needed. This study was carried out to evaluate the effects of dibutyltin (IV) ethylphenyldithiocarbamate (DBEP), diphenyltin (IV) ethylphenyldithiocarbamate (DPEP) and triphenyltin (IV) ethylphenyldithiocarbamate (TPEP) compounds as antimalarial agents. These compounds were evaluated against erythrocytes infected with Plasmodium berghei NK65 via ex vivo. Organotin (IV) ethylphenyldithiocarbamate, [R(n)Sn(C9H10NS2)(4-n)] with R = C4H9 and C6H5 for n = 2; R = C6H5 for n = 3 is chemically synthesised for its potential activities. pLDH assay was employed for determination of the concentration that inhibited 50% of the Plasmodium's activity (IC50) after 24 h treatment at concentration range of 10-0.0000001 mg mL(-1). Plasmodium berghei NK65 was cultured in vitro to determine the different morphology of trophozoite and schizont. Only DPEP and TPEP compounds have antimalarial activity towards P. berghei NK65 at IC50 0.094±0.011 and 0.892±0.088 mg mL(-1), respectively. The IC50 of DPEP and TPEP were lowest at 30% parasitemia with IC50 0.001±0.00009 and 0.0009±0.0001 mg mL(-1), respectively. In vitro culture showed that TPEP was effective towards P. berghei NK65 in trophozoite and schizont morphology with IC50 0.0001±0.00005 and 0.00009±0.00003 μg mL(-1), respectively. In conclusion, DPEP and TPEP have antimalarial effect on erythrocytes infected with P. berghei NK65 and have potential as antimalarial and schizonticidal agents. PMID:26035957

  15. Co-infection with Plasmodium berghei and Trypanosoma brucei increases severity of malaria and trypanosomiasis in mice.

    PubMed

    Ademola, Isaiah Oluwafemi; Odeniran, Paul Olalekan

    2016-07-01

    Individuals in natural populations may be infected with multiple different parasites at a time. These parasites may interact with each other or act independently in the host, and this may result to varying outcomes on host health and survival. This study therefore aimed at investigating the health impact of co-infection of mice with Plasmodium berghei and Trypanosoma brucei. Forty Swiss albino mice (14-17g) were divided into four groups of ten. Mice in groups A and B received 10(6)P. berghei and groups B and C 10(5)T. brucei, while group D were uninfected. The co-infected mice had higher P. berghei and T. brucei parasitaemia, compared with the mono-infected mice. The co-infected mice had significantly (p<0.05) lower survival rate compared with the mono-infected mice. Co-infection of mice with P. berghei and T. brucei resulted in rapid P. berghei and T. brucei development and increased parasitaemia. The leukocyte numbers significantly (p<0.05) reduced on days 12 and 15 post infection among P. berghei infected mice, in the presence or absence of T. brucei. Anaemia and hypoglycaemia was more severe in the co-infected mice. Therefore, co-infection of mice with P. berghei and T. brucei may increase pathologic impact to the host by increasing parasitaemia. PMID:27021269

  16. 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

  17. Role of the aryl hydrocarbon receptor in the immune response profile and development of pathology during Plasmodium berghei Anka infection.

    PubMed

    Brant, Fatima; Miranda, Aline S; Esper, Lisia; Rodrigues, David Henrique; Kangussu, Lucas Miranda; Bonaventura, Daniella; Soriani, Frederico Marianetti; Pinho, Vanessa; Souza, Danielle G; Rachid, Milene Alvarenga; Weiss, Louis M; Tanowitz, Herbert B; Teixeira, Mauro Martins; Teixeira, Antônio Lucio; Machado, Fabiana Simão

    2014-08-01

    Infection with Plasmodium falciparum may result in severe disease affecting various organs, including liver, spleen, and brain, resulting in high morbidity and mortality. Plasmodium berghei Anka infection of mice recapitulates many features of severe human malaria. The aryl hydrocarbon receptor (AhR) is an intracellular receptor activated by ligands important in the modulation of the inflammatory response. We found that AhR-knockout (KO) mice infected with P. berghei Anka displayed increased parasitemia, earlier mortality, enhanced leukocyte-endothelial cell interactions in the brain microvasculature, and increased inflammation in brain (interleukin-17 [IL-17] and IL-6) and liver (gamma interferon [IFN-γ] and tumor necrosis factor alpha [TNF-α]) compared to infected wild-type (WT) mice. Infected AhR-KO mice also displayed a reduction in cytokines required for host resistance, including TNF-α, IL-1β, and IFN-γ, in the brain and spleen. Infection of AhR-KO mice resulted in an increase in T regulatory cells and transforming growth factor β, IL-6, and IL-17 in the brain. AhR modulated the basal expression of SOCS3 in spleen and brain, and P. berghei Anka infection resulted in enhanced expression of SOCS3 in brain, which was absent in infected AhR-KO mice. These data suggest that AhR-mediated control of SOCS3 expression is probably involved in the phenotype seen in infected AhR-KO mice. This is, to our knowledge, the first demonstration of a role for AhR in the pathogenesis of malaria. PMID:24818665

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

    PubMed Central

    2004-01-01

    Copper, like iron, is a transition metal that can generate oxygen radicals by the Fenton reaction. The Plasmodium parasite invades an erythrocyte host cell containing 20 μM copper, of which 70% is contained in the Cu/Zn SOD (cuprozinc superoxide dismutase). In the present study, we follow the copper pathways in the Plasmodium-infected erythrocyte. Metal-determination analysis shows that the total copper content of Percoll-purified trophozoite-stage-infected erythrocytes is 66% that of uninfected erythrocytes. This decrease parallels the decrease seen in Cu/Zn SOD levels in parasite-infected erythrocytes. Neocuproine, an intracellular copper chelator, arrests parasites at the ring-to-trophozoite stage transition and also specifically decreases intraparasitic levels of Cu/Zn SOD and catalase. Up to 150 μM BCS (2,9-dimethyl-4,7-diphenyl-1,10-phenanthrolinedisulphonic acid), an extracellular copper chelator, has no effect on parasite growth. We characterized a single copy PfCuP-ATPase (Plasmodium falciparum copper P-ATPase) transporter, which, like the Crypto-sporidium parvum copper P-ATPase, has a single copper-binding domain: ‘Met-Xaa-Cys-Xaa-Xaa-Cys’. Recombinant expression of the N-terminal metal-binding domain reveals that the protein specifically binds reduced copper. Transcription of the PfCuP-ATPase gene is the highest at late ring stage/early trophozoite, and is down-regulated in the presence of neocuproine. Immunofluorescence and electron microscopy indicate the transporter to be both in the parasite and on the erythrocyte membrane. Both the decrease in total copper and the location of the PfCuP-ATPase gene indicate a copper-efflux pathway from the infected erythrocyte. PMID:15125686

  19. Fosmidomycin Uptake into Plasmodium and Babesia-Infected Erythrocytes Is Facilitated by Parasite-Induced New Permeability Pathways

    PubMed Central

    Reichenberg, Armin; Hintz, Martin; Bietz, Sven; Harb, Omar S.; Roos, David S.; Kordes, Maximilian; Friesen, Johannes; Matuschewski, Kai; Lingelbach, Klaus; Jomaa, Hassan; Seeber, Frank

    2011-01-01

    Background Highly charged compounds typically suffer from low membrane permeability and thus are generally regarded as sub-optimal drug candidates. Nonetheless, the highly charged drug fosmidomycin and its more active methyl-derivative FR900098 have proven parasiticidal activity against erythrocytic stages of the malaria parasite Plasmodium falciparum. Both compounds target the isoprenoid biosynthesis pathway present in bacteria and plastid-bearing organisms, like apicomplexan parasites. Surprisingly, the compounds are inactive against a range of apicomplexans replicating in nucleated cells, including Toxoplasma gondii. Methodology/Principal Findings Since non-infected erythrocytes are impermeable for FR90098, we hypothesized that these drugs are taken up only by erythrocytes infected with Plasmodium. We provide evidence that radiolabeled FR900098 accumulates in theses cells as a consequence of parasite-induced new properties of the host cell, which coincide with an increased permeability of the erythrocyte membrane. Babesia divergens, a related parasite that also infects human erythrocytes and is also known to induce an increase in membrane permeability, displays a similar susceptibility and uptake behavior with regard to the drug. In contrast, Toxoplasma gondii-infected cells do apparently not take up the compounds, and the drugs are inactive against the liver stages of Plasmodium berghei, a mouse malaria parasite. Conclusions/Significance Our findings provide an explanation for the observed differences in activity of fosmidomycin and FR900098 against different Apicomplexa. These results have important implications for future screens aimed at finding new and safe molecular entities active against P. falciparum and related parasites. Our data provide further evidence that parasite-induced new permeability pathways may be exploited as routes for drug delivery. PMID:21573242

  20. The practice of jhum cultivation and its relationship to Plasmodium falciparum infection in the Chittagong Hill Districts of Bangladesh.

    PubMed

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

    2014-08-01

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

  1. Plasmodium falciparum msp2 Genotypes and Multiplicity of Infections among Children under Five Years with Uncomplicated Malaria in Kibaha, Tanzania

    PubMed Central

    Kidima, W.; Nkwengulila, G.

    2015-01-01

    Genetic diversity of Plasmodium falciparum may pose challenges in malaria treatment and prevention through chemotherapy and vaccination. We assessed Plasmodium falciparum genetic diversity and multiplicity of infection (MOI) of P. falciparum infections and sort relationship of parasitaemia with P. falciparum msp2 genotypes as well as with the number of infecting clones. The study was carried out in Kibaha, Tanzania. Ninety-nine children under five years with uncomplicated malaria were recruited. Genetic diversity was analyzed by genotyping the msp2 gene using PCR-Restriction Fragment Length Polymorphism. Thirty-two different msp2 alleles were obtained. The msp2 3D7 allelic frequency was higher (48.1%) and more prevalent than FC27 (27.3%) (p < 0.05). Twenty-four percent of the infections were mixed alleles. The individuals with FC27 had high parasitemia compared to those with 3D7 alleles (p = 0.038). The mean MOI was low (1.4 clones, 95% CI 1.2–1.5). The P. falciparum population among children at Kibaha is composed of distinct P. falciparum clones, and parasites having 3D7 are more frequent than those with FC27 alleles. Individuals with parasite having FC27 alleles have high parasite densities suggesting that parasites with FC27 alleles may associate with severity of disease in Kibaha. Low MOI at Kibaha suggests low malaria transmission rate. PMID:26770821

  2. Exposure of Plasmodium sporozoites to the intracellular concentration of potassium enhances infectivity and reduces cell passage activity.

    PubMed

    Kumar, Kota Arun; Garcia, Celia R S; Chandran, Vandana R; Van Rooijen, N; Zhou, Yingyao; Winzeler, Elizabeth; Nussenzweig, Victor

    2007-11-01

    Malaria sporozoites migrate through several cells prior to a productive invasion that involves the formation of a parasitophorous vacuole (PV) where sporozoites undergo transformation into Exo-erythorcytic forms (EEFs). The precise mechanism leading to sporozoite activation for invasion is unknown, but prior traversal of host cells is required. During cell migration sporozoites are exposed to large shifts in K(+) concentration. We report here that incubation of sporozoites to the intracellular K(+) concentration enhances 8-10 times the infectivity of Plasmodium berghei and 4-5 times the infectivity of Plasmodium yoelli sporozoites for a hepatocyte cell line, while simultaneously decreasing cell passage activity. The K(+) enhancing effect was time and concentration dependent, and was significantly decreased by K(+) channel inhibitors. Potassium-treated P. berghei sporozoites also showed enhanced numbers of EEFs in non-permissive cell lines. Treated sporozoites had reduced infectivity for mice, but infectivity was enhanced upon Kupffer cell depletion. Transcriptional analysis of K(+) treated and control sporozoites revealed a high degree of correlation in their levels of gene expression, indicating that the observed phenotypic changes are not due to radical changes in gene transcription. Only seven genes were upregulated by more than two-fold in K(+) treated sporozoites. The highest level was noted in PP2C, a phosphatase known to dephosphorylate the AKT potassium channel in plants. PMID:17714805

  3. Pivotal and distinct role for Plasmodium actin capping protein alpha during blood infection of the malaria parasite

    PubMed Central

    Ganter, Markus; Rizopoulos, Zaira; Schüler, Herwig; Matuschewski, Kai

    2015-01-01

    Accurate regulation of microfilament dynamics is central to cell growth, motility and response to environmental stimuli. Stabilizing and depolymerizing proteins control the steady-state levels of filamentous (F-) actin. Capping protein (CP) binds to free barbed ends, thereby arresting microfilament growth and restraining elongation to remaining free barbed ends. In all CPs characterized to date, alpha and beta subunits form the active heterodimer. Here, we show in a eukaryotic parasitic cell that the two CP subunits can be functionally separated. Unlike the beta subunit, the CP alpha subunit of the apicomplexan parasite Plasmodium is refractory to targeted gene deletion during blood infection in the mammalian host. Combinatorial complementation of Plasmodium berghei CP genes with the orthologs from Plasmodium falciparum verified distinct activities of CP alpha and CP alpha/beta during parasite life cycle progression. Recombinant Plasmodium CP alpha could be produced in Escherichia coli in the absence of the beta subunit and the protein displayed F-actin capping activity. Thus, the functional separation of two CP subunits in a parasitic eukaryotic cell and the F-actin capping activity of CP alpha expand the repertoire of microfilament regulatory mechanisms assigned to CPs. PMID:25565321

  4. Rouleaux-forming serum proteins are involved in the rosetting of Plasmodium falciparum-infected erythrocytes.

    PubMed

    Treutiger, C J; Scholander, C; Carlson, J; McAdam, K P; Raynes, J G; Falksveden, L; Wahlgren, M

    1999-12-01

    Excessive sequestration of Plasmodium falciparum-infected (pRBC) and uninfected erythrocytes (RBC) in the microvasculature, cytoadherence, and rosetting, have been suggested to be correlated with the development of cerebral malaria. P. falciparum erythrocyte membrane protein-1 (PfEMP1) is the parasite-derived adhesin which mediates rosetting. Herein we show that serum proteins are crucial for the rosette formation of four strains of parasites (FCR3S1, TM284, TM180, and R29), whereas the rosettes of a fifth strain (DD2) are serum independent. Some parasites, e.g., FCR3S1, can be depleted of all rosettes by washes in heparin and Na citrate and none of the rosettes remain when the parasite is grown in foetal calf serum or ALBUMAX. Rosettes of other parasites are less sensitive; e.g., 20% of TM180 and R29 and 70% of TM284 rosettes still prevail after cultivation. A serum fraction generated by ion-exchange chromatography and poly-ethylene-glycol precipitation restored 50% of FCR3S1 and approx 40 to 100% of TM180 rosettes. In FCR3S1, antibodies to fibrinogen reverted the effect of the serum fraction and stained fibrinogen bound to the pRBC surface in transmission electron microscopy. Normal, nonimmune IgM and/or IgG was also found attached to the pRBC of the four serum-dependent strains as seen by surface immunofluorescens. Our results suggest that serum proteins, known to participate in rouleaux formation of normal erythrocytes, produce stable rosettes in conjunction with the recently identified parasite-derived rosetting ligand PfEMP1. PMID:10600447

  5. 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

  6. Increased detection of Plasmodium knowlesi in Sandakan division, Sabah as revealed by PlasmoNex™

    PubMed Central

    2013-01-01

    Background Plasmodium knowlesi is a simian malaria parasite that is widespread in humans in Malaysian Borneo. However, little is known about the incidence and distribution of this parasite in the Sandakan division, Malaysian Borneo. Therefore, the aim of the present epidemiological study was to investigate the incidence and distribution of P. knowlesi as well as other Plasmodium species in this division based on a most recent developed hexaplex PCR system (PlasmoNex™). Methods A total of 189 whole blood samples were collected from Telupid Health Clinic, Sabah, Malaysia, from 2008 to 2011. All patients who participated in the study were microscopically malaria positive before recruitment. Complete demographic details and haematological profiles were obtained from 85 patients (13 females and 72 males). Identification of Plasmodium species was conducted using PlasmoNex™ targeting the 18S ssu rRNA gene. Results A total of 178 samples were positive for Plasmodium species by using PlasmoNex™. Plasmodium falciparum was identified in 68 samples (38.2%) followed by 64 cases (36.0%) of Plasmodium vivax, 42 (23.6%) cases of P. knowlesi, two (1.1%) cases of Plasmodium malariae and two (1.1%) mixed-species infections (i e, P. vivax/P. falciparum). Thirty-five PlasmoNex™ positive P. knowlesi samples were misdiagnosed as P. malariae by microscopy. Plasmodium knowlesi was detected in all four districts of Sandakan division with the highest incidence in the Kinabatangan district. Thrombocytopaenia and anaemia showed to be the most frequent malaria-associated haematological complications in this study. Conclusions The discovery of P. knowlesi in Sandakan division showed that prospective studies on the epidemiological risk factors and transmission dynamics of P. knowlesi in these areas are crucial in order to develop strategies for effective malaria control. The availability of advanced diagnostic tool PlasmoNex™ enhanced the accuracy and accelerated the speed in the

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

    PubMed Central

    2013-01-01

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

  8. Inflammatory changes in the central nervous system are associated with behavioral impairment in Plasmodium berghei (strain ANKA)-infected mice

    PubMed Central

    Lacerda-Queiroz, Norinne; Rodrigues, David Henrique; Vilela, Márcia Carvalho; de Miranda, Aline Silva; Amaral, Débora Cristina Guerra; Camargos, Elizabeth Ribeiro da Silva; de Moura Carvalho, Leonardo José; Howe, Charles L; Teixeira, Mauro Martins; Teixeira, Antônio Lúcio

    2011-01-01

    Experimental cerebral malaria is a neuroinflammatory condition that results from the host immune response to the parasite. Using intravital microscopy, we investigated leukocyte recruitment in the brain microcirculation and the temporal relationship of this process to the behavioral changes observed in Plasmodium berghei (strain ANKA)-infected C57Bl/6 mice. We found that leukocyte recruitment was increased from day 5 post-infection (p.i.) onwards. Histopathological changes and increased levels of inflammatory cytokines in the brain were also observed. Behavioral performance evaluated by the SHIRPA protocol showed functional impairment from day 6 p.i. onwards. Thus, early leukocyte migration into the brain and associated inflammatory changes may be involved in neurological impairment in parasite-infected C57Bl/6 mice. PMID:20138873

  9. 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

  10. Neither mosquito saliva nor immunity to saliva has a detectable effect on the infectivity of Plasmodium sporozoites injected into mice.

    PubMed

    Kebaier, Chahnaz; Voza, Tatiana; Vanderberg, Jerome

    2010-01-01

    Malaria infection is initiated when a female Anopheles mosquito probing for blood injects saliva, together with sporozoites, into the skin of its mammalian host. Prior studies had suggested that saliva may enhance sporozoite infectivity. Using rodent malaria models (Plasmodium berghei and P. yoelii), we were unable to show that saliva had any detectable effect on sporozoite infectivity. This is encouraging for plans to immunize humans with washed, attenuated P. falciparum sporozoites because many individuals develop cutaneous, hypersensitivity reactions to mosquito saliva after repeated exposure. If washed sporozoites have no appreciable loss of infectivity, they likely do not have decreased immunogenicity; thus, vaccinees are unlikely to develop cutaneous reactions against mosquito saliva during attempted immunization with such sporozoites. Earlier studies also suggested that repeated prior exposure to mosquito saliva reduces infectivity of sporozoites injected by mosquitoes into sensitized hosts. However, our own studies show that prior exposure of mice to saliva had no detectable effect on numbers of sporozoites delivered by infected mosquitoes, the rate of disappearance of these sporozoites from the skin or infectivity of the sporozoites. Under natural conditions, sporozoites are delivered both to individuals who may exhibit cutaneous hypersensitivity to mosquito bite and to others who may have not yet developed such reactivity. It was tempting to hypothesize that differences in responsiveness to mosquito bite by different individuals might modulate the infectivity of sporozoites delivered into a milieu of changes induced by cutaneous hypersensitivity. Our results with rodent malaria models, however, were unable to support such a hypothesis. PMID:19884338

  11. Renal related disorders in concomitant Schistosoma haematobium-Plasmodium falciparum infection among children in a rural community of Nigeria.

    PubMed

    Morenikeji, Olajumoke A; Eleng, Ituna E; Atanda, Omotayo S; Oyeyemi, Oyetunde T

    2016-01-01

    Schistosomiasis and malaria are two common parasitic diseases that are co-endemic in resource-poor communities of sub-Saharan Africa. This study aims to assess the effects of single and concomitant Plasmodium falciparum and Schistosoma haematobium infections on two indicators of renal injury in school children in a rural community of Nigeria. A cross-sectional epidemiological survey was carried out on a total of 173 schoolchildren between ages 6 and 18 years (mean age 11.4±2.6 years). Urine and blood samples were collected by standard methods for concurrent microscopic diagnosis of S. haematobium and P. falciparum infections. Urinary blood (hematuria) and protein were determined using a urinalysis dipstick. The prevalence of single infections was 75.1% and 78.2% for S. haematobium and P. falciparum, respectively. A total of 57.1% individuals were infected with the two parasites. The prevalence of hematuria was significantly higher in the co-infection status (63.8%) than in single S. haematobium (52.2%) and P. falciparum (43.7%) infection statuses (p=0.04), while no significant variation was recorded in proteinuria in the three infection statuses (p=0.53). The proportion of children with renal injury associated with the co-infection of these parasites is very high, particularly in young children, who seem to have a higher prevalence of hematuria. PMID:26220794

  12. Efficacy of integrated school based de-worming and prompt malaria treatment on helminths -Plasmodium falciparum co-infections: A 33 months follow up study

    PubMed Central

    2011-01-01

    Background The geographical congruency in distribution of helminths and Plasmodium falciparum makes polyparasitism a common phenomenon in Sub Saharan Africa. The devastating effects of helminths-Plasmodium co-infections on primary school health have raised global interest for integrated control. However little is known on the feasibility, timing and efficacy of integrated helminths-Plasmodium control strategies. A study was conducted in Zimbabwe to evaluate the efficacy of repeated combined school based antihelminthic and prompt malaria treatment. Methods A cohort of primary schoolchildren (5-17 years) received combined Praziquantel, albendazole treatment at baseline, and again during 6, 12 and 33 months follow up surveys and sustained prompt malaria treatment. Sustained prompt malaria treatment was carried out throughout the study period. Children's infection status with helminths, Plasmodium and helminths-Plasmodium co-infections was determined by parasitological examinations at baseline and at each treatment point. The prevalence of S. haematobium, S. mansoni, STH, malaria, helminths-Plasmodium co-infections and helminths infection intensities before and after treatment were analysed. Results Longitudinal data showed that two rounds of combined Praziquantel and albendazole treatment for schistosomiasis and STHs at 6 monthly intervals and sustained prompt malaria treatment significantly reduced the overall prevalence of S. haematobium, S. mansoni, hookworms and P. falciparum infection in primary schoolchildren by 73.5%, 70.8%, 67.3% and 58.8% respectively (p < 0.001, p < 0.001, p < 0.001, p < 0.001 respectively). More importantly, the prevalence of STH + schistosomes, P. f + schistosomes, and P. f + STHs + schistosomes co-infections were reduced by 68.0%, 84.2%, and 90.7%, respectively. The absence of anti-helminthic treatment between the 12 mth and 33 mth follow-up surveys resulted in the sharp increase in STHs + schistosomes co-infection from 3.3% at 12 months

  13. Natural infection of Plasmodium brasilianum in humans: Man and monkey share quartan malaria parasites in the Venezuelan Amazon

    PubMed Central

    Lalremruata, Albert; Magris, Magda; Vivas-Martínez, Sarai; Koehler, Maike; Esen, Meral; Kempaiah, Prakasha; Jeyaraj, Sankarganesh; Perkins, Douglas Jay; Mordmüller, Benjamin; Metzger, Wolfram G.

    2015-01-01

    Background The quartan malaria parasite Plasmodium malariae is the widest spread and best adapted human malaria parasite. The simian Plasmodium brasilianum causes quartan fever in New World monkeys and resembles P. malariae morphologically. Since the genetics of the two parasites are nearly identical, differing only in a range of mutations expected within a species, it has long been speculated that the two are the same. However, no naturally acquired infection with parasites termed as P. brasilianum has been found in humans until now. Methods We investigated malaria cases from remote Yanomami indigenous communities of the Venezuelan Amazon and analyzed the genes coding for the circumsporozoite protein (CSP) and the small subunit of ribosomes (18S) by species-specific PCR and capillary based-DNA sequencing. Findings Based on 18S rRNA gene sequencing, we identified 12 patients harboring malaria parasites which were 100% identical with P. brasilianum isolated from the monkey, Alouatta seniculus. Translated amino acid sequences of the CS protein gene showed identical immunodominant repeat units between quartan malaria parasites isolated from both humans and monkeys. Interpretation This study reports, for the first time, naturally acquired infections in humans with parasites termed as P. brasilianum. We conclude that quartan malaria parasites are easily exchanged between humans and monkeys in Latin America. We hypothesize a lack of host specificity in mammalian hosts and consider quartan malaria to be a true anthropozoonosis. Since the name P. brasilianum suggests a malaria species distinct from P. malariae, we propose that P. brasilianum should have a nomenclatorial revision in case further research confirms our findings. The expansive reservoir of mammalian hosts discriminates quartan malaria from other Plasmodium spp. and requires particular research efforts. PMID:26501116

  14. Spatially-explicit risk profiling of Plasmodium falciparum infections at a small scale: a geostatistical modelling approach

    PubMed Central

    Silué, Kigbafori D; Raso, Giovanna; Yapi, Ahoua; Vounatsou, Penelope; Tanner, Marcel; N'Goran, Eliézer K; Utzinger, Jürg

    2008-01-01

    Background There is a renewed political will and financial support to eradicate malaria. Spatially-explicit risk profiling will play an important role in this endeavour. Patterns of Plasmodium falciparum infection prevalence were examined among schoolchildren in a highly malaria-endemic area. Methods A questionnaire was administered and finger prick blood samples collected from 3,962 children, aged six to 16 years, attending 55 schools in a rural part of western Côte d'Ivoire. Information was gathered from the questionnaire on children's socioeconomic status and the use of bed nets for the prevention of malaria. Blood samples were processed with standardized, quality-controlled methods for diagnosis of Plasmodium spp. infections. Environmental data were obtained from satellite images and digitized maps. Bayesian variogram models for spatially-explicit risk modelling of P. falciparum infection prevalence were employed, assuming for stationary and non-stationary spatial processes. Findings The overall prevalence of P. falciparum infection was 64.9%, ranging between 34.0% and 91.9% at the unit of the school. Risk factors for a P. falciparum infection included age, socioeconomic status, not sleeping under a bed net, distance to health care facilities and a number of environmental features (i.e. normalized difference vegetation index, rainfall and distance to rivers). After taking into account spatial correlation only age remained significant. Non-stationary models performed better than stationary models. Conclusion Spatial risk profiling of P. falciparum prevalence data provides a useful tool for targeting malaria control intervention, and hence will play a role in the quest of local elimination and ultimate eradication of the disease. PMID:18570685

  15. Reduced CD36-dependent tissue sequestration of Plasmodium-infected erythrocytes is detrimental to malaria parasite growth in vivo

    PubMed Central

    Fonager, Jannik; Pasini, Erica M.; Braks, Joanna A.M.; Klop, Onny; Ramesar, Jai; Remarque, Edmond J.; Vroegrijk, Irene O.C.M.; van Duinen, Sjoerd G.; Thomas, Alan W.; Khan, Shahid M.; Mann, Matthias; Kocken, Clemens H.M.; Janse, Chris J.

    2012-01-01

    Adherence of parasite-infected red blood cells (irbc) to the vascular endothelium of organs plays a key role in the pathogenesis of Plasmodium falciparum malaria. The prevailing hypothesis of why irbc adhere and sequester in tissues is that this acts as a mechanism of avoiding spleen-mediated clearance. Irbc of the rodent parasite Plasmodium berghei ANKA sequester in a fashion analogous to P. falciparum by adhering to the host receptor CD36. To experimentally determine the significance of sequestration for parasite growth, we generated a mutant P. berghei ANKA parasite with a reduced CD36-mediated adherence. Although the cognate parasite ligand binding to CD36 is unknown, we show that nonsequestering parasites have reduced growth and we provide evidence that in addition to avoiding spleen removal, other factors related to CD36-mediated sequestration are beneficial for parasite growth. These results reveal for the first time the importance of sequestration to a malaria infection, with implications for the development of strategies aimed at reducing pathology by inhibiting tissue sequestration. PMID:22184632

  16. Differential expression of var gene groups is associated with morbidity caused by Plasmodium falciparum infection in Tanzanian children.

    PubMed

    Rottmann, Matthias; Lavstsen, Thomas; Mugasa, Joseph Paschal; Kaestli, Mirjam; Jensen, Anja T R; Müller, Dania; Theander, Thor; Beck, Hans-Peter

    2006-07-01

    The var gene family of Plasmodium falciparum encodes the variant surface antigen Plasmodium falciparum erythrocyte membrane protein 1 (PfEMP1). PfEMP1 is considered an important pathogenicity factor in P. falciparum infection because it mediates cytoadherence to host cell endothelial receptors. var genes can be grouped into three major groups, A, B, and C, and the conserved var genes, var1-4, according to sequence similarities in coding and noncoding upstream regions. Using real-time quantitative PCR in a study conducted in Tanzania, the var transcript abundances of the different var gene groups were compared among patients with severe, uncomplicated, and asymptomatic malaria. Transcripts of var group A and B genes were more abundant in patients with severe malaria than in patients with uncomplicated malaria. In general, the transcript abundances of var group A and B genes were higher for children with clinical malaria than for children with asymptomatic infections. The var group C and var1-like transcript abundances were similar between the three sample groups. A transcript abundance pattern similar to that for var group A was observed for var2csa and var3-like genes. These results suggest that substantial and systematic differences in var gene expression exist between different clinical presentations. PMID:16790763

  17. Crystal Structure of Arginase from Plasmodium falciparum and Implications for l-Arginine Depletion in Malarial Infection

    SciTech Connect

    Dowling, Daniel P.; Ilies, Monica; Olszewski, Kellen L.; Portugal, Silvia; Mota, Maria M.; Llinas, Manuel; Christianson, David W.

    2010-09-03

    The 2.15 {angstrom} resolution crystal structure of arginase from Plasmodium falciparum, the parasite that causes cerebral malaria, is reported in complex with the boronic acid inhibitor 2(S)-amino-6-boronohexanoic acid (ABH) (K{sub d} = 11 {micro}M). This is the first crystal structure of a parasitic arginase. Various protein constructs were explored to identify an optimally active enzyme form for inhibition and structural studies and to probe the structure and function of two polypeptide insertions unique to malarial arginase: a 74-residue low-complexity region contained in loop L2 and an 11-residue segment contained in loop L8. Structural studies indicate that the low-complexity region is largely disordered and is oriented away from the trimer interface; its deletion does not significantly compromise enzyme activity. The loop L8 insertion is located at the trimer interface and makes several intra- and intermolecular interactions important for enzyme function. In addition, we also demonstrate that arg- Plasmodium berghei sporozoites show significantly decreased liver infectivity in vivo. Therefore, inhibition of malarial arginase may serve as a possible candidate for antimalarial therapy against liver-stage infection, and ABH may serve as a lead for the development of inhibitors.

  18. Inference of the Oxidative Stress Network in Anopheles stephensi upon Plasmodium Infection

    PubMed Central

    Shrinet, Jatin; Nandal, Umesh Kumar; Adak, Tridibes; Bhatnagar, Raj K.; Sunil, Sujatha

    2014-01-01

    Ookinete invasion of Anopheles midgut is a critical step for malaria transmission; the parasite numbers drop drastically and practically reach a minimum during the parasite's whole life cycle. At this stage, the parasite as well as the vector undergoes immense oxidative stress. Thereafter, the vector undergoes oxidative stress at different time points as the parasite invades its tissues during the parasite development. The present study was undertaken to reconstruct the network of differentially expressed genes involved in oxidative stress in Anopheles stephensi during Plasmodium development and maturation in the midgut. Using high throughput next generation sequencing methods, we generated the transcriptome of the An. stephensi midgut during Plasmodium vinckei petteri oocyst invasion of the midgut epithelium. Further, we utilized large datasets available on public domain on Anopheles during Plasmodium ookinete invasion and Drosophila datasets and arrived upon clusters of genes that may play a role in oxidative stress. Finally, we used support vector machines for the functional prediction of the un-annotated genes of An. stephensi. Integrating the results from all the different data analyses, we identified a total of 516 genes that were involved in oxidative stress in An. stephensi during Plasmodium development. The significantly regulated genes were further extracted from this gene cluster and used to infer an oxidative stress network of An. stephensi. Using system biology approaches, we have been able to ascertain the role of several putative genes in An. stephensi with respect to oxidative stress. Further experimental validations of these genes are underway. PMID:25474020

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

    Technology Transfer Automated Retrieval System (TEKTRAN)

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

  20. Antibodies to Malaria Vaccine Candidates Pvs25 and Pvs28 Completely Block the Ability of Plasmodium vivax To Infect Mosquitoes

    PubMed Central

    Hisaeda, Hajime; Stowers, Anthony W.; Tsuboi, Takafumi; Collins, William E.; Sattabongkot, Jetsumon S.; Suwanabun, Natavadee; Torii, Motomi; Kaslow, David C.

    2000-01-01

    Transmission-blocking vaccines are one strategy for controlling malaria, whereby sexual-stage parasites are inhibited from infecting mosquitoes by human antibodies. To evaluate whether the recently cloned Plasmodium vivax proteins Pvs25 and Pvs28 are candidates for a transmission-blocking vaccine, the molecules were expressed in yeast as secreted recombinant proteins. Mice vaccinated with these proteins adsorbed to aluminum hydroxide developed strong antibody responses against the immunogens, although for Pvs28, this response was genetically restricted. Antisera against both recombinant Pvs25 and Pvs28 recognized the corresponding molecules expressed by cultured sexual-stage parasites isolated from patients with P. vivax malaria. The development of malaria parasites in mosquitoes was completely inhibited when these antisera were ingested with the infected blood meal. Pvs25 and Pvs28, expressed in Saccharomyces cerevisiae, are as yet the only fully characterized transmission-blocking vaccine candidates against P. vivax that induce such a potent antiparasite response. PMID:11083773

  1. Artemisinin-resistant Plasmodium falciparum clinical isolates can infect diverse mosquito vectors of Southeast Asia and Africa

    PubMed Central

    St. Laurent, Brandyce; Miller, Becky; Burton, Timothy A.; Amaratunga, Chanaki; Men, Sary; Sovannaroth, Siv; Fay, Michael P.; Miotto, Olivo; Gwadz, Robert W.; Anderson, Jennifer M.; Fairhurst, Rick M.

    2015-01-01

    Artemisinin-resistant Plasmodium falciparum parasites are rapidly spreading in Southeast Asia, yet nothing is known about their transmission. This knowledge gap and the possibility that these parasites will spread to Africa endanger global efforts to eliminate malaria. Here we produce gametocytes from parasite clinical isolates that displayed artemisinin resistance in patients and in vitro, and use them to infect native and non-native mosquito vectors. We show that contemporary artemisinin-resistant isolates from Cambodia develop and produce sporozoites in two Southeast Asian vectors, Anopheles dirus and Anopheles minimus, and the major African vector, Anopheles coluzzii (formerly Anopheles gambiae M). The ability of artemisinin-resistant parasites to infect such highly diverse Anopheles species, combined with their higher gametocyte prevalence in patients, may explain the rapid expansion of these parasites in Cambodia and neighbouring countries, and further compromise efforts to prevent their global spread. PMID:26485448

  2. Artemisinin-resistant Plasmodium falciparum clinical isolates can infect diverse mosquito vectors of Southeast Asia and Africa.

    PubMed

    St Laurent, Brandyce; Miller, Becky; Burton, Timothy A; Amaratunga, Chanaki; Men, Sary; Sovannaroth, Siv; Fay, Michael P; Miotto, Olivo; Gwadz, Robert W; Anderson, Jennifer M; Fairhurst, Rick M

    2015-01-01

    Artemisinin-resistant Plasmodium falciparum parasites are rapidly spreading in Southeast Asia, yet nothing is known about their transmission. This knowledge gap and the possibility that these parasites will spread to Africa endanger global efforts to eliminate malaria. Here we produce gametocytes from parasite clinical isolates that displayed artemisinin resistance in patients and in vitro, and use them to infect native and non-native mosquito vectors. We show that contemporary artemisinin-resistant isolates from Cambodia develop and produce sporozoites in two Southeast Asian vectors, Anopheles dirus and Anopheles minimus, and the major African vector, Anopheles coluzzii (formerly Anopheles gambiae M). The ability of artemisinin-resistant parasites to infect such highly diverse Anopheles species, combined with their higher gametocyte prevalence in patients, may explain the rapid expansion of these parasites in Cambodia and neighbouring countries, and further compromise efforts to prevent their global spread. PMID:26485448

  3. The seroprevalence of avipoxvirus and its association with avian malaria (Plasmodium spp.) infection in introduced passerine birds in the southern regions of the North Island of New Zealand.

    PubMed

    Ha, H J; Banda, M; Alley, M R; Howe, L; Gartrell, B D

    2013-03-01

    Blood samples were collected from 65 free-ranging birds from six species in the southern North Island of New Zealand. Sera from the birds were tested for the presence of avipoxvirus (APV) antibodies by enzyme-linked immunosorbent assay (ELISA), and blood cells from 55 birds were also tested for Plasmodium spp. by PCR. Forty-five birds (69.2%) tested seropositive to APV. Song thrushes (Turdus philomelos) presented the highest seroprevalence at 100% (4/4), followed by Eurasian blackbirds (Turdus merula) (96.86%, 31/32), chaffinches (Fringilla coelebs) (54.55%, 6/11), starlings (Sturnus vulgaris) (25%, 3/12), greenfinches (Carduelis chloris) (25%, 1/4), and European goldfinches (Carduelis carduelis) (0%, 0/2). Plasmodium spp. DNA was detected in 15/55 birds (27.3%), including 11 Eurasian blackbirds, one song thrush, and three starlings. Eight Eurasian blackbird isolates (73%) grouped within the subgenus Novyella. Two Eurasian blackbird isolates and the song thrush isolate clustered within a different group with previously reported lineages LINN1 and AFTRU5. In addition, all three starling isolates clustered within the well-characterized lineage Plasmodium (Huffia) elongatum GRW06. All Plasmodium-positive Eurasian blackbirds and the song thrush were seropositive to APV, whereas only 67% of Plasmodium-positive starlings showed evidence of previous exposure to APV. A significant relationship between birds seropositive to APV and birds infected by Plasmodium spp. was observed (chi2 = 5.69, df = 1, P = 0.0086). To the authors' knowledge this is the first report describing the seroprevalence of APV and its association with Plasmodium spp. infection in introduced bird species in New Zealand. PMID:23678738

  4. The role of regulatory T cells during Plasmodium chabaudi chabaudi AS infection in BALB/c mice.

    PubMed

    Pang, W; Sun, X; Feng, H; Wang, J; Cui, L; Cao, Y

    2016-07-01

    An inappropriate immune response to parasite infection is one of the primary drivers of malaria pathogenesis. Regulatory T cells (Tregs), an important subset of CD4(+) T cells, can maintain self-tolerance and prevent autoimmune diseases. However, there is little consensus about their role in malaria pathogenesis. In this study, we transiently depleted Tregs (CD25(+) T cells) using an anti-CD25 mAb (7D4 clone) at different time points following Plasmodium chabaudi chabaudi AS infection in BALB/c mice and investigated the effect of depletion of Tregs in this model. In control mice, Tregs proliferated significantly and their suppressive function was enhanced after infection. IL-10 was increased drastically during infection. Depletion of Tregs at various time points can lead to divergent outcomes. When Tregs were depleted prior to or during the early phase of infection, most mice survived and had a robust Th1 immune response. In contrast, when Tregs were depleted close to peak parasitemia, all mice died as a result of inflammation. Taken together, these data suggest that in P. c. chabaudi AS-infected BALB/c mice, Tregs inhibit the Th1 response and macrophage activation, leading to increased parasite load; however, they also control inflammation-mediated pathology by secreting high levels of IL-10. PMID:27139002

  5. Protective Effects of Tinospora crispa Stem Extract on Renal Damage and Hemolysis during Plasmodium berghei Infection in Mice

    PubMed Central

    Nutham, Narain; Sakulmettatham, Sakuna; Klongthalay, Suwit; Chutoam, Palatip; Somsak, Voravuth

    2015-01-01

    Renal damage and hemolysis induced by malaria are associated with mortality in adult patients. It has been speculated that oxidative stress condition induced by malaria infection is involved in its pathology. Thus, we aimed to investigate the protective effects of Tinospora crispa stem extract on renal damage and hemolysis during Plasmodium berghei infection. T. crispa stem extract was prepared using hot water method and used for oral treatment in mice. Groups of ICR mice were infected with 1 × 107 parasitized erythrocytes of P. berghei ANKA by intraperitoneal injection and given the extracts (500, 1000, and 2000 mg/kg) twice a day for 4 consecutive days. To assess renal damage and hemolysis, blood urea nitrogen (BUN), creatinine, and hematocrit (%Hct) levels were then evaluated, respectively. Malaria infection resulted in renal damage and hemolysis as indicated by increasing of BUN and creatinine and decreasing of %Hct, respectively. However, protective effects on renal damage and hemolysis were observed in infected mice treated with these extracts at doses of 1000 and 2000 mg/kg. In conclusion, T. crispa stem extract exerted protective effects on renal damage and hemolysis induced by malaria infection. This plant may work as potential source in the development of variety of herbal formulations for malarial treatment. PMID:26600953

  6. Protective Effects of Tinospora crispa Stem Extract on Renal Damage and Hemolysis during Plasmodium berghei Infection in Mice.

    PubMed

    Nutham, Narain; Sakulmettatham, Sakuna; Klongthalay, Suwit; Chutoam, Palatip; Somsak, Voravuth

    2015-01-01

    Renal damage and hemolysis induced by malaria are associated with mortality in adult patients. It has been speculated that oxidative stress condition induced by malaria infection is involved in its pathology. Thus, we aimed to investigate the protective effects of Tinospora crispa stem extract on renal damage and hemolysis during Plasmodium berghei infection. T. crispa stem extract was prepared using hot water method and used for oral treatment in mice. Groups of ICR mice were infected with 1 × 10(7) parasitized erythrocytes of P. berghei ANKA by intraperitoneal injection and given the extracts (500, 1000, and 2000 mg/kg) twice a day for 4 consecutive days. To assess renal damage and hemolysis, blood urea nitrogen (BUN), creatinine, and hematocrit (%Hct) levels were then evaluated, respectively. Malaria infection resulted in renal damage and hemolysis as indicated by increasing of BUN and creatinine and decreasing of %Hct, respectively. However, protective effects on renal damage and hemolysis were observed in infected mice treated with these extracts at doses of 1000 and 2000 mg/kg. In conclusion, T. crispa stem extract exerted protective effects on renal damage and hemolysis induced by malaria infection. This plant may work as potential source in the development of variety of herbal formulations for malarial treatment. PMID:26600953

  7. 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

  8. Characterization of asymptomatic Plasmodium falciparum infection and its risk factors in pregnant women from the Republic of Congo.

    PubMed

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

    2016-01-01

    Malaria in pregnancy remains a serious public health problem in the Republic of Congo despite the implementation of intermittent preventive treatment with sulfadoxine-pyrimethamine (IPTp-SP) in 2006. The aim of this cross-sectional study was to characterize Plasmodium falciparum infections and determine possible risk factors in pregnant Congolese women attending an antenatal clinic in a periurban area of southern Brazzaville. This study was conducted from March 2012 to December 2013 in a site where several years ago, high malaria resistance to SP was reported. Pregnant women were enrolled during antenatal visits and the number of received IPTp-SP doses was recorded as well as individual sociodemographic data. Peripheral blood was collected and P. falciparum infection was checked by microscopy and by PCR targeting P. falciparum merozoite surface protein gene (msp2). Haemoglobin concentration was measured and P. falciparum positive samples were typed for msp2 allelic diversity. A total of 363 pregnant women were recruited. The prevalence of asymptomatic P. falciparum infection was 7% and 19% by microscopy and by PCR, respectively. More than one half (51.5%) of the pregnant women were anaemic. Multivariate analysis indicated that P. falciparum infection was associated with anaemia. It was also observed that women who have received IPTp-SP have significantly lower prevalence of infection. The administration of IPTp-SP did not influence the multiplicity of infection (MOI). This first study investigating asymptomatic malaria infection on pregnant women of the Republic of Congo shows that P. falciparum infections were clearly associated with maternal anaemia, and use of IPTp-SP reduced the risk of carrying asymptomatic infections. PMID:26477849

  9. Depletion of Phagocytic Cells during Nonlethal Plasmodium yoelii Infection Causes Severe Malaria Characterized by Acute Renal Failure in Mice.

    PubMed

    Terkawi, Mohamad Alaa; Nishimura, Maki; Furuoka, Hidefumi; Nishikawa, Yoshifumi

    2016-03-01

    In the current study, we examined the effects of depletion of phagocytes on the progression of Plasmodium yoelii 17XNL infection in mice. Strikingly, the depletion of phagocytic cells, including macrophages, with clodronate in the acute phase of infection significantly reduced peripheral parasitemia but increased mortality. Moribund mice displayed severe pathological damage, including coagulative necrosis in liver and thrombi in the glomeruli, fibrin deposition, and tubular necrosis in kidney. The severity of infection was coincident with the increased sequestration of parasitized erythrocytes, the systematic upregulation of inflammation and coagulation, and the disruption of endothelial integrity in the liver and kidney. Aspirin was administered to the mice to minimize the risk of excessive activation of the coagulation response and fibrin deposition in the renal tissue. Interestingly, treatment with aspirin reduced the parasite burden and pathological lesions in the renal tissue and improved survival of phagocyte-depleted mice. Our data imply that the depletion of phagocytic cells, including macrophages, in the acute phase of infection increases the severity of malarial infection, typified by multiorgan failure and high mortality. PMID:26755155

  10. 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

  11. Expression of senescent antigen on erythrocytes infected with a knobby variant of the human malaria parasite Plasmodium falciparum

    SciTech Connect

    Winograd, E.; Greenan, J.R.T.; Sherman, I.W.

    1987-04-01

    Erythrocytes infected with a knobby variant of Plasmodium falciparum selectively bind IgG autoantibodies in normal human serum. Quantification of membrane-bound IgG, by use of /sup 125/I-labeled protein A, revealed that erythrocytes infected with the knobby variant bound 30 times more protein A than did noninfected erythrocytes; infection with a knobless variant resulted in less than a 2-fold difference compared with noninfected erythrocytes. IgG binding to knobby erythrocytes appeared to be related to parasite development, since binding of /sup 125/I-labeled protein A to cells bearing young trophozoites (less than 20 hr after parasite invasion) was similar to binding to uninfected erythrocytes. By immunoelectron microscopy, the membrane-bound IgG on erythrocytes infected with the knobby variant was found to be preferentially associated with the protuberances (knobs) of the plasma membrane. The removal of aged or senescent erythrocytes from the peripheral circulation is reported to involve the binding of specific antibodies to an antigen (senescent antigen) related to the major erythrocyte membrane protein band 3. Since affinity-purified autoantibodies against band 3 specifically bound to the plasma membrane of erythrocytes infected with the knobby variant of P. falciparum, it is clear that the malaria parasite induces expression of senescent antigen.

  12. Infection of Laboratory-Colonized Anopheles darlingi Mosquitoes by Plasmodium vivax

    PubMed Central

    Moreno, Marta; Tong, Carlos; Guzmán, Mitchel; Chuquiyauri, Raul; Llanos-Cuentas, Alejandro; Rodriguez, Hugo; Gamboa, Dionicia; Meister, Stephan; Winzeler, Elizabeth A.; Maguina, Paula; Conn, Jan E.; Vinetz, Joseph M.

    2014-01-01

    Anopheles darlingi Root is the most important malaria vector in the Amazonia region of South America. However, continuous propagation of An. darlingi in the laboratory has been elusive, limiting entomological, genetic/genomic, and vector–pathogen interaction studies of this mosquito species. Here, we report the establishment of an An. darlingi colony derived from wild-caught mosquitoes obtained in the northeastern Peruvian Amazon region of Iquitos in the Loreto Department. We show that the numbers of eggs, larvae, pupae, and adults continue to rise at least to the F6 generation. Comparison of feeding Plasmodium vivax ex vivo of F4 and F5 to F1 generation mosquitoes showed the comparable presence of oocysts and sporozoites, with numbers that corresponded to blood-stage asexual parasitemia and gametocytemia, confirming P. vivax vectorial capacity in the colonized mosquitoes. These results provide new avenues for research on An. darlingi biology and study of An. darlingi–Plasmodium interactions. PMID:24534811

  13. Immunization with Apical Membrane Antigen 1 Confers Sterile Infection-Blocking Immunity against Plasmodium Sporozoite Challenge in a Rodent Model

    PubMed Central

    Schussek, Sophie; Trieu, Angela; Apte, Simon H.; Sidney, John; Sette, Alessandro

    2013-01-01

    Apical membrane antigen 1 (AMA-1) is a leading blood-stage malaria vaccine candidate. Consistent with a key role in erythrocytic invasion, AMA-1-specific antibodies have been implicated in AMA-1-induced protective immunity. AMA-1 is also expressed in sporozoites and in mature liver schizonts where it may be a target of protective cell-mediated immunity. Here, we demonstrate for the first time that immunization with AMA-1 can induce sterile infection-blocking immunity against Plasmodium sporozoite challenge in 80% of immunized mice. Significantly higher levels of gamma interferon (IFN-γ)/interleukin-2 (IL-2)/tumor necrosis factor (TNF) multifunctional T cells were noted in immunized mice than in control mice. We also report the first identification of minimal CD8+ and CD4+ T cell epitopes on Plasmodium yoelii AMA-1. These data establish AMA-1 as a target of both preerythrocytic- and erythrocytic-stage protective immune responses and validate vaccine approaches designed to induce both cellular and humoral immunity. PMID:23836827

  14. In vitro infectivity of irradiated Plasmodium berghei sporozoites to cultured hepatoma cells

    SciTech Connect

    Sigler, C.I.; Leland, P.; Hollingdale, M.R.

    1984-07-01

    The invasion of gamma-irradiated Plasmodium berghei sporozoites into cultured hepatoma cells and their transformation into trophozoites was similar to invasion and transformation of non-irradiated sporozoites. However, trophozoites from irradiated sporozoites did not further develop into schizonts, but persisted within the cells for up to 3 days. Sporozoite surface protective antigen was present in trophozoites from irradiated and non-irradiated sporozoites, suggesting that hepatocyte antigen processing may contribute to the induction of anti-malarial immunity.

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

    PubMed

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

    2016-05-01

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

  16. Preventive (myoglobin, transferrin) and scavenging (superoxide dismutase, glutathione peroxidase) anti-oxidative properties of raw liquid extract of Morinda lucida leaf in the traditional treatment of Plasmodium infection

    PubMed Central

    Olaniyan, Mathew Folaranmi; Babatunde, Elizabeth Moyinoluwa

    2016-01-01

    Background: Liquid extract of Morinda lucida leaf has been demonstrated to have antiplasmodial activities. Some phytochemicals act as preventive and or scavenging antioxidants. This study aimed to investigate the preventative and scavenging properties of the raw liquid extract of M. lucida leaf using plasma myoglobin, transferrin, superoxide dismutase (SOD), and glutathione (GSH) peroxidase. Materials and Methods: Forty-eight Plasmodium-infected patients aged 29-47 years that have not been treated with any antimalaria medication but have decided to be treated traditionally using M. lucida leaf extract were recruited from 15 traditional homes in ATISBO, Saki-East, and Saki-West local government areas of Oke-Ogun — the Northern part of Oyo State-Nigeria. Identification of Plasmodium in the blood of the test and normal control subjects were carried out by Giemsha thick film technique. Packed cell volume, total bile acids, blood glucose, blood pressure, plasma myoglobin, transferrin, SOD, and GSH peroxidase (GPx) were evaluated in the normal control subjects and in the Plasmodium-infected patients before and after the treatment with raw liquid extract of M. lucida leaf. Results: A significant (P < 0.05) biochemical alterations were observed in the plasma values of transferrin, SOD, and GPx in the Plasmodium-infected patients when compared with the normal control subjects and after treatment with the raw liquid extract of M. lucida leaf. Conclusion: Our study supports the possible preventative and scavenging antioxidative effect of the raw liquid extract of M. lucida leaf in the traditional treatment of Plasmodium infection. PMID:27003969

  17. Plasmodium falciparum Malaria Challenge by the Bite of Aseptic Anopheles stephensi Mosquitoes: Results of a Randomized Infectivity Trial

    PubMed Central

    Lyke, Kirsten E.; Laurens, Matthew; Adams, Matthew; Billingsley, Peter F.; Richman, Adam; Loyevsky, Mark; Chakravarty, Sumana; Plowe, Christopher V.; Sim, B. Kim Lee; Edelman, Robert; Hoffman, Stephen L.

    2010-01-01

    Background Experimental infection of malaria-naïve volunteers by the bite of Plasmodium falciparum-infected mosquitoes is a preferred means to test the protective effect of malaria vaccines and drugs. The standard model relies on the bite of five infected mosquitoes to induce malaria. We examined the efficacy of malaria transmission using mosquitoes raised aseptically in compliance with current Good Manufacturing Practices (cGMPs). Methods and Findings Eighteen adults aged 18–40 years were randomized to receive 1, 3 or 5 bites of Anopheles stephensi mosquitoes infected with the chloroquine-sensitive NF54 strain of P. falciparum. Seventeen participants developed malaria; fourteen occurring on Day 11. The mean prepatent period was 10.9 days (9–12 days). The geometric mean parasitemia was 15.7 parasites/µL (range: 4–70) by microscopy. Polymerase chain reaction (PCR) detected parasites 3.1 (range: 0–4) days prior to microscopy. The geometric mean sporozoite load was 16,753 sporozoites per infected mosquito (range: 1,000–57,500). A 1-bite participant withdrew from the study on Day 13 post-challenge and was PCR and smear negative. Conclusions The use of aseptic, cGMP-compliant P. falciparum-infected mosquitoes is safe, is associated with a precise prepatent period compared to the standard model and appears more efficient than the standard approach, as it led to infection in 100% (6/6) of volunteers exposed to three mosquito bites and 83% (5/6) of volunteers exposed to one mosquito bite. Trial Registration ClinicalTrials.gov NCT00744133 PMID:21042404

  18. Insights Into Circulating Cytokine Dynamics During Pregnancy in HIV-Infected Beninese Exposed to Plasmodium falciparum Malaria.

    PubMed

    Ibitokou, Samad A; Denoeud-Ndam, Lise; Ezinmegnon, Sèm; Ladékpo, Rodolphe; Zannou, Djimon-Marcel; Massougbodji, Achille; Girard, Pierre-Marie; Cot, Michel; Luty, Adrian J F; Ndam, Nicaise Tuikue

    2015-08-01

    We investigated the circulating plasma levels of Th1- (Interleukin-2 [IL-2], tumor necrosis factor-α [TNF-α], interferon-gamma [IFN-γ]) and Th2-type (IL-4, IL-5, IL-10) cytokines in human immunodeficiency virus (HIV)-infected pregnant women living in a malaria-endemic area. We analyzed samples from 200 pregnant women included in the prevention of pregnancy-associated malaria in HIV-infected women: cotrimoxazole prophylaxis versus mefloquine (PACOME) clinical trial who were followed until delivery. Cytokine concentrations were measured by flow cytometry-based multiplex bead array. Significantly elevated levels of IL-10 and lower levels of TNF-α were observed at delivery compared with inclusion (P = 0.005). At inclusion, the presence of circulating IFN-γ, a higher CD4(+) T cell count and having initiated intermittent preventive treatment of malaria with sulfadoxine pyrimethamine (SP-IPTp) were all associated with a lower likelihood of Plasmodium falciparum infection. At delivery, the inverse relationship between the presence of infection and circulating IFN-γ persisted, although there was a positive association between the likelihood of infection and the presence of circulating TNF-α. Initiation of antiretroviral therapy was associated with elevated IL-5 production. Consistent with our own and others' observations in HIV seronegative subjects, this study shows circulating IL-10 to be a marker of infection with P. falciparum during pregnancy even in HIV-infected women, although plasma IFN-γ may be a marker of anti-malarial protection in such women. PMID:26101276

  19. NOS2 Variants Reveal a Dual Genetic Control of Nitric Oxide Levels, Susceptibility to Plasmodium Infection, and Cerebral Malaria

    PubMed Central

    Trovoada, Maria de Jesus; Martins, Madalena; Ben Mansour, Riadh; Sambo, Maria do Rosário; Fernandes, Ana B.; Antunes Gonçalves, Lígia; Borja, Artur; Moya, Roni; Almeida, Paulo; Costa, João; Marques, Isabel; Macedo, M. Paula; Coutinho, António; Narum, David L.

    2014-01-01

    Nitric oxide (NO) is a proposed component of malaria pathogenesis, and the inducible nitric oxide synthase gene (NOS2) has been associated to malaria susceptibility. We analyzed the role of NOS2 polymorphisms on NO bioavailability and on susceptibility to infection, Plasmodium carrier status and clinical malaria. Two distinct West African sample collections were studied: a population-based collection of 1,168 apparently healthy individuals from the Príncipe Island and a hospital-based cohort of 269 Angolan children. We found that two NOS2 promoter single-nucleotide polymorphism (SNP) alleles associated to low NO plasma levels in noninfected individuals were also associated to reduced risk of pre-erythrocytic infection as measured anti-CSP antibody levels (6.25E–04 < P < 7.57E–04). In contrast, three SNP alleles within the NOS2 cistronic region conferring increased NO plasma levels in asymptomatic carriers were strongly associated to risk of parasite carriage (8.00E–05 < P < 7.90E–04). Notwithstanding, three SNP alleles in this region protected from cerebral malaria (7.90E–4 < P < 4.33E–02). Cohesively, the results revealed a dual regimen in the genetic control of NO bioavailability afforded by NOS2 depending on the infection status. NOS2 promoter variants operate in noninfected individuals to decrease both NO bioavailability and susceptibility to pre-erythrocytic infection. Conversely, NOS2 cistronic variants (namely, rs6505469) operate in infected individuals to increase NO bioavailability and confer increased susceptibility to unapparent infection but protect from cerebral malaria. These findings corroborate the hypothesis that NO anti-inflammatory properties impact on different steps of malaria pathogenesis, explicitly by favoring infection susceptibility and deterring severe malaria syndromes. PMID:24379293

  20. Mixed species radioiodine air sampling readout and dose assessment system

    DOEpatents

    Distenfeld, Carl H.; Klemish, Jr., Joseph R.

    1978-01-01

    This invention provides a simple, reliable, inexpensive and portable means and method for determining the thyroid dose rate of mixed airborne species of solid and gaseous radioiodine without requiring highly skilled personnel, such as health physicists or electronics technicians. To this end, this invention provides a means and method for sampling a gas from a source of a mixed species of solid and gaseous radioiodine for collection of the mixed species and readout and assessment of the emissions therefrom by cylindrically, concentrically and annularly molding the respective species around a cylindrical passage for receiving a conventional probe-type Geiger-Mueller radiation detector.

  1. Ticket to ride: export of proteins to the Plasmodium falciparum-infected erythrocyte.

    PubMed

    Przyborski, Jude M; Nyboer, Britta; Lanzer, Michael

    2016-07-01

    The malaria parasite Plasmodium falciparum exports numerous proteins to its chosen host cell, the mature human erythrocyte. Many of these proteins are important for parasite survival. To reach the host cell, parasites must cross multiple membrane barriers and then furthermore be targeted to their correct sub-cellular localisation. This novel transport pathway has received much research attention in the past decades, especially as many of the mechanisms are expected to be parasite-specific and thus potential targets for drug development. In this article we summarize some of the most recent advances in this field, and highlight areas in which further research is needed. PMID:26996123

  2. Co-infection of human parvovirus B19 with Plasmodium falciparum contributes to malaria disease severity in Gabonese patients

    PubMed Central

    2013-01-01

    Background High seroprevalence of parvovirus B19 (B19V) coinfection with Plasmodium falciparum has been previously reported. However, the impact of B19V-infection on the clinical course of malaria is still elusive. In this study, we investigated the prevalence and clinical significance of B19V co-infection in Gabonese children with malaria. Methods B19V prevalence was analyzed in serum samples of 197 Gabonese children with P. falciparum malaria and 85 healthy controls using polymerase chain reaction (PCR), enzyme-linked immunosorbent assay (ELISA), and direct DNA-sequencing. Results B19V was detected in 29/282 (10.28%) of Gabonese children. B19V was observed more frequently in P. falciparum malaria patients (14.21%) in comparison to healthy individuals (1.17%) (P<0.001). Notably, the mild-malaria group revealed significantly lower hematocrit levels in B19V/P. falciparum co-infection than in P. falciparum mono-infection (P<0.05). Genetic analysis revealed a predominance of B19V genotype-1 (71.43%) in the studied population. However, B19V-genotype 2 was observed significantly more often in children with severe-malaria than in mild-malaria (P=0.04). Conclusion Our findings reveal that B19V-infection is frequent in Gabonese children with P. falciparum malaria and signifies a possible contribution of B19V on the clinical course of malaria in a genotype-dependent manner. B19V co-infection should be considered as a additional diagnostic measure in malaria patients with life threatening anemia. PMID:23945350

  3. Plasmodium falciparum infection and age influence parasite growth inhibition mediated by IgG in Beninese infants.

    PubMed

    Adamou, Rafiou; Chénou, Francine; Sadissou, Ibrahim; Sonon, Paulin; Dechavanne, Célia; Djilali-Saïah, Abdelkader; Cottrell, Gilles; Le Port, Agnès; Massougbodji, Achille; Remarque, Edmond J; Luty, Adrian J F; Sanni, Ambaliou; Garcia, André; Migot-Nabias, Florence; Milet, Jacqueline; Courtin, David

    2016-07-01

    Antibodies that impede the invasion of Plasmodium falciparum (P. falciparum) merozoites into erythrocytes play a critical role in anti-malarial immunity. The Growth Inhibition Assay (GIA) is an in vitro measure of the functional capacity of such antibodies to limit erythrocyte invasion and/or parasite growth. Up to now, it is unclear whether growth-inhibitory activity correlates with protection from clinical disease and there are inconsistent results from studies performed with GIA. Studies that have focused on the relationship between IgGs and their in vitro parasite Growth Inhibition Activity (GIAc) in infants aged less than two years old are rare. Here, we used clinical and parasitological data to precisely define symptomatic or asymptomatic infection with P. falciparum in groups of infants followed-up actively for 18 months post-natally. We quantified the levels of IgG1 and IgG3 directed to a panel of candidate P. falciparum vaccine antigens (AMA-1, MSP1, 2, 3 and GLURP) using ELISA and the functional activity of IgG was quantified using GIA. Data were then correlated with individuals' infection status. At 18 months of age, infants harbouring infections at the time of blood sampling had an average 19% less GIAc than those not infected (p=0.004, multivariate linear regression). GIAc decreased from 12 to 18 months of age (p=0.003, Wilcoxon matched pairs test). Antibody levels quantified at 18 months in infants were strongly correlated with their exposure to malarial infection, however GIAc was not correlated with malaria infectious status (asymptomatic and symptomatic groups). In conclusion, both infection status at blood draw and age influence parasite growth inhibition mediated by IgG in the GIA. Both factors must be taken into account when correlations between GIAc and anti-malarial protection or vaccine efficacy have to be made. PMID:27001144

  4. Submicroscopic Infections with Plasmodium falciparum during Pregnancy and Their Association with Circulating Cytokine, Chemokine, and Cellular Profiles

    PubMed Central

    Ibitokou, Samad A.; Boström, Stéphanie; Brutus, Laurent; Tuikue Ndam, Nicaise; Vianou, Bertin; Agbowaï, Carine; Amadoudji Zin, Martin; Huynh, Bich Tram; Massougbodji, Achille; Deloron, Philippe; Troye-Blomberg, Marita; Fievet, Nadine

    2014-01-01

    The immunological consequences of pregnancy-associated malaria (PAM) due to Plasmodium falciparum have been extensively investigated in cross-sectional studies conducted at delivery, but there have been very few longitudinal studies of changes due to PAM during pregnancy. We conducted a prospective study in Benin to investigate the changes associated with PAM in groups of 131 and 111 women at inclusion in the second trimester and at delivery, respectively. Infected women were identified by standard microscopic examinations of blood smears and by quantitative PCR (qPCR) assays and were matched to uninfected control women by age, gestational age, and gravidity. We quantified plasma levels of a panel of soluble immunological mediators and other mediators, as well as the frequencies of peripheral blood mononuclear cell types. Comparisons of these variables in infected and uninfected women used multivariate analyses, and we also assessed the predictive value of variables measured at inclusion for pregnancy outcomes at delivery. In multivariate analyses, peripheral plasma interleukin 10 (IL-10) and gamma interferon-inducible protein 10 (IP-10) levels were associated with PAM at inclusion and at delivery, while higher IL-10 levels distinguished qPCR-detectable submicroscopic infections at inclusion but not at delivery. Maternal anemia at delivery was associated with markers of proinflammatory (increased frequency of monocytes) and anti-inflammatory (increased IL-10 levels and increased activation of regulatory T cells) activity measured at inclusion. Elevated concentrations of IL-10 are associated with the majority of P. falciparum infections during pregnancy, but this marker alone does not identify all submicroscopic infections. Reliably identifying such occult infections will require more sensitive and specific methods. PMID:24717969

  5. Submicroscopic infection of placenta by Plasmodium produces Th1/Th2 cytokine imbalance, inflammation and hypoxia in women from north-west Colombia

    PubMed Central

    2014-01-01

    Background A large-scale study was set up in order to study the epidemiology, clinical aspects, and immunopathology of gestational and placental malaria in north-west Colombia. In this region, recent reports using a qPCR technique, confirmed frequencies of infection, by Plasmodium falciparum or Plasmodium vivax, up to 45%. Given the high rates of infection observed both in mother and placenta, a first exploratory study was proposed in order to characterize the effect on the inflammation status, tissue damage and hypoxia in Plasmodium spp. infected placentas. Methods A descriptive, prospective, cross-sectional design was applied to pregnant women with (PM+) and without (PM-) placental malaria. Messenger RNA expression of Fas, FasL; COX-1, COX-2, HIF, VEGF, and the cytokines IL-2, IL-4, IL-10, IFN-γ and TNF, were measured in peripheral and placental blood using a quantitative PCR. The percentage of apoptotic cells was determined with a TUNEL assay. Results In total 50 placentas were studied: 25 were positive for submicroscopic infection and 25 were negative for Plasmodium infection. Expression of IL-4 and IL-10 was observed high in placental tissue of PM+, while IL-2 was high in peripheral blood of the same group. Expression of TNF and IFNγ in peripheral blood of the PM + group was high. Similarly, the apoptotic index and Fas expression were significantly high in PM+. However, FasL expression was observed low in PM + compared to PM-. Inflammation markers (HIF, VEGF) and hypoxia markers (COX-1, COX-2) were high in the PM + group. Conclusion During placental malaria expression of some pro-inflammatory cytokines is up-regulated and markers of hypoxia and tissue damage are increased in cases of submicroscopic infection. PMID:24673747

  6. Unlike the synchronous Plasmodium falciparum and P. chabaudi infection, the P. berghei and P. yoelii asynchronous infections are not affected by melatonin

    PubMed Central

    Bagnaresi, Piero; Alves, Eduardo; da Silva, Henrique Borges; Epiphanio, Sabrina; Mota, Maria M; Garcia, Célia RS

    2009-01-01

    We have previously reported that Plasmodium chabaudi and P. falciparum sense the hormone melatonin and this could be responsible for the synchrony of malaria infection. In P. chabaudi and P. falciparum, melatonin induces calcium release from internal stores, and this response is abolished by U73122, a phospholipase C inhibitor, and luzindole, a melatonin-receptor competitive antagonist. Here we show that, in vitro, melatonin is not able to modulate cell cycle, nor to elicit an elevation in intracellular calcium concentration of the intraerythrocytic forms of P. berghei or P. yoelii, two rodent parasites that show an asynchrononous development in vivo. Interestingly, melatonin and its receptor do not seem to play a role during hepatic infection by P. berghei sporozoites either. These data strengthen the hypothesis that host-derived melatonin does not synchronize malaria infection caused by P. berghei and P. yoelii. Moreover, these data explain why infections by these parasites are asynchronous, contrary to what is observed in P. falciparum and P. chabaudi infections. PMID:20360886

  7. Decreased sensitivity of artesunate and chloroquine of Plasmodium falciparum infecting hemoglobin H and/or hemoglobin constant spring erythrocytes.

    PubMed Central

    Yuthavong, Y; Butthep, P; Bunyaratvej, A; Fucharoen, S

    1989-01-01

    Plasmodium falciparum infecting hemoglobin (Hb) H and/or Hb Constant Spring erythrocytes in vitro was relatively more resistant than that infecting normal erythrocytes to artesunate and chloroquine, while the sensitivity to pyrimethamine was unchanged. The 50% inhibitory concentrations (IC50) for artesunate in HbH (alpha-thal 1/alpha-thal 2), HbH (alpha-thal 1/Hb Constant Spring), and homozygous Hb Constant Spring erythrocytes were 4.5 +/- 2.8, 8.5 +/- 3.2, and 2.6 +/- 1.6 nM compared with 0.82 +/- 0.35 nM in normal erythrocytes (P less than 0.002 for all three cases). The IC50 for chloroquine were 97 +/- 46, 162 +/- 67, and 93 +/- 36 nM, respectively, in the variant erythrocytes, compared with 48 +/- 13 nM in normal erythrocytes (P less than 0.002, 0.002, and 0.02, respectively). The differences in sensitivity to artesunate and chloroquine of the parasite infecting HbH erythrocytes are probably related to their oxidative mode of action and relatively high amounts of antioxidant enzymes in the host erythrocytes. This novel example of dependence on the host of the malarial parasite drug sensitivity may have implications for chemotherapy of malaria in patients with genetically variant erythrocytes. PMID:2643631

  8. Wildlife disease and conservation in Hawaii: pathogenicity of avian malaria (Plasmodium relictum) in experimentally infected Iiwi (Vestiaria coccinea)

    USGS Publications Warehouse

    Atkinson, C.T.; Woods, K.L.; Dusek, R.J.; Sileo, L.S.; Iko, W.M.

    1995-01-01

    Native Hawaiian forest birds are facing a major extinction crisis with more than 75% of species recorded in historical times either extinct or endangered. Reasons for this catastrophe include habitat destruction, competition with non-native species, and introduction of predators and avian diseases. We tested susceptibility of Iiwi (Vestiaria coccinea), a declining native species, and Nutmeg Mannikins (Lonchura punctulata), a common non-native species, to an isolate of Plasmodium relictum from the island of Hawaii. Food consumption, weight, and parasitaemia were monitored in juvenile Iiwi that were infected by either single (low-dose) or multiple (high-dose) mosquito bites. Mortality in both groups was significantly higher than in uninfected controls, reaching 100% of high-dose birds and 90% of low-dose birds. Significant declines in food consumption and a corresponding loss of body weight occurred in malaria-infected birds. Both sex and body weight had significant effects on survival time, with males more susceptible than females and birds with low initial weights more susceptible than those with higher initial weights. Gross and microscopic lesions in malaria fatalities included massive enlargement of the spleen and liver, hyperplasia of the reticuloendothelial system with extensive deposition of malarial pigment, and overwhelming anaemia in which over 30% of the circulating erythrocytes were parasitized. Nutmeg Mannikins, by contrast, were completely refractory to infection. Our findings support previous studies documenting high susceptibility of native Hawaiian forest birds to avian malaria. This disease continues to threaten remaining high elevation populations of endangered native birds.

  9. Plasmodium vivax infection in Anajás, State of Pará: no differential resistance profile among Duffy-negative and Duffy-positive individuals

    PubMed Central

    2012-01-01

    Background There is large body of evidence that states that invasion of Plasmodium vivax requires the Duffy antigen, but the universality of this specificity is certainly now under question with recent reports showing that in some parts of the world P. vivax infects and causes disease in Duffy-negative people. These findings reinforce the idea that this parasite is rapidly evolving, being able to use other receptors than Duffy to invade the erythrocytes, which may have an enormous impact in P. vivax current distribution. The presence of P. vivax infection in Duffy-negative individuals was investigated in a cross-sectional study conducted in Anajás, Archipelago of Marajó, State of Pará, which is an area of malaria transmission in the Brazilian Amazonia. Methods Duffy genotyping and Plasmodium species diagnostic assays were performed successfully in 678 individuals. An allele-specific primer polymerase chain reaction (PCR) technique was used for Duffy blood group genotyping. Identification of Plasmodium species was achieved by conventional blood smear light microscopy and a TaqMan-based real-time PCR method to detect mitochondrial genome of Plasmodium falciparum and P. vivax. Results Plasmodium spp. infection was detected in 137 samples (20.2%). Prevalence of each Plasmodium species was 13.9% P. vivax, 5.8% P. falciparum, and 0.6% P. vivax plus P. falciparum. Overall, 4.3% (29/678) were genotyped as Duffy-negative (FY*BES/*BES). Among Duffy-negative individuals 6.9% were P. vivax PCR positive and among Duffy-positive 14.2% were P. vivax PCR positive. Although lower, the risk of Duffy-negatives to experience a P. vivax blood stage infection was not significantly different to that of Duffy-positives. Furthermore, the genotypic and allelic frequencies of the Duffy blood group among P. vivax-infected patients and in the control group did not differ significantly, also suggesting no reduction in infection rates among the carriers of FY*BES allele. Conclusions The data

  10. Seasonal pattern of avian Plasmodium-infected mosquitoes and implications for parasite transmission in central Panama.

    PubMed

    Loaiza, Jose R; Miller, Matthew J

    2013-11-01

    Aedeomyia squamipennis and Culex (Melanoconion) ocossa, two ubiquitous Neotropical mosquito species, are likely involved in the transmission of several bird pathogens in Gamboa, central Panama. However, knowledge on their eco-epidemiological profiles is still incomplete. Our goal in this study was to investigate temporal trends of vector density and their relationship with avian plasmodia prevalence. This information is central to identifying the risk posed by each vector species to the avian community locally. We found that A. squamipennis maintains stable population size across climatic seasons and thus maybe a more efficient vector of avian malaria than C. ocossa. In contrast, C. ocossa, which undergoes considerable population expansion in the rainy season and contraction in the dry season, is likely only an important avian malaria vector during part of the year. This is consistent with the larger number of parasite isolations and Plasmodium cyt b lineages recovered from A. squamipennis than from C. ocossa and might be explained by marked differences in their seasonality and host-feeding preferences. More Plasmodium PCR testing in mosquito communities from other areas of Panama might reveal additional vectors of avian plasmodia. PMID:23974324

  11. Cytokine response to pregnancy-associated recrudescence of Plasmodium berghei infection in mice with pre-existing immunity to malaria

    PubMed Central

    2013-01-01

    Background During childhood, residents of areas with stable transmission of Plasmodium falciparum parasites acquire substantial protective immunity to malaria, and adults therefore rarely experience clinical disease episodes. However, susceptibility to infection reappears in pregnant women, particularly primigravidae. This is due to appearance of antigenic parasite variants that are restricted to pregnancy. Variant-specific immunity also governs pregnancy-associated recrudescence of Plasmodium berghei infection in pregnant mice. Pregnancy-related changes in the plasma cytokine levels of mice with immunity acquired prior to first pregnancy have not been studied in detail previously, and were the topic of the present study. Methods A multiplexed bead assay was used to measure plasma levels of IL-5, IL-10, IL-12, IL-13, IFN-γ and TNF in BALB/c mice immunized against P. berghei K173 by repeated infection and drug cure before the first pregnancy. The association between cytokine levels on the one hand and parasitaemia and haemoglobin levels on the other, in mice that had never been pregnant or were pregnant for the first, second or third time were evaluated by Mann–Whitney test and Spearman rank-order correlation analysis. Results Pregnancy per se did not further increase the already high cytokine levels in mice previously immunized by repeated infection and drug cure. Levels of all the cytokines except IL-10 were correlated with each other, and with parasitaemia and haemoglobin levels. Furthermore, levels of all cytokines were positively correlated with parity, except IL-10, which was negatively correlated with parity. High levels of IL-10 and low levels of the other cytokines were associated with poor pregnancy outcome. Conclusions High levels of IL-10 and low levels of the other cytokines were associated with poor pregnancy outcome in this mouse model of placental malaria. Since the model replicates key parasitological and immunological features of placental P

  12. Field performance of malaria rapid diagnostic test for the detection of Plasmodium falciparum infection in Odisha State, India

    PubMed Central

    Sahu, S.S.; Gunasekaran, K.; Jambulingam, P.

    2015-01-01

    Background & objectives: Rapid diagnostic tests (RDTs) have become an essential surveillance tool in the malaria control programme in India. The current study aimed to assess the performance of ParaHIT-f, a rapid test in diagnosis of Plasmodium falciparum infection through detecting its specific antigen, histidine rich protein 2 (PfHRP-2), in Odisha State, India. Methods: The study was undertaken in eight falciparum malaria endemic southern districts of Odisha State. Febrile patients included through active case detection, were diagnosed by Accredited Social Health Activists (ASHAs) for P. falciparum infection using the RDT, ParaHIT-f. The performance of ParaHIT-f was evaluated using microscopy as the gold standard. Results: A total of 1030 febrile patients were screened by both microscopy and the RDT for P. falciparum infection. The sensitivity of ParaHIT-f was 63.6% (95% CI: 56.0-70.6) and specificity was 98.9% (95% CI: 97.9-99.5), with positive and negative predictive values (PPV and NPV) of 92.6% (95% CI: 86.0-96.3) and 93.0% (95% CI: 91.0-94.5), respectively. When related to parasitaemia, the RDT sensitivity was 47.8% at the low parasitaemia of 4 to 40 parasites/μl of blood. Interpretation & conclusions: The results showed that the performance of the RDT, ParaHIT-f, was not as sensitive as microscopy in detecting true falciparum infections; a high specificity presented a low frequency of false-positive RDT results. The sensitivity of ParaHIT-f was around 60 per cent. It is, therefore, essential to improve the efficiency (sensitivity) of the kit so that the true falciparum infections will not be missed especially in areas where P. falciparum has been the predominant species causing cerebral malaria. PMID:26905242

  13. Association between Landscape Factors and Spatial Patterns of Plasmodium knowlesi Infections in Sabah, Malaysia

    PubMed Central

    Abidin, Tommy Rowel; Alexander, Neal; Brock, Paddy; Grigg, Matthew J.; Murphy, Amanda; William, Timothy; Menon, Jayaram; Drakeley, Chris J.; Cox, Jonathan

    2016-01-01

    The zoonotic malaria species Plasmodium knowlesi has become the main cause of human malaria in Malaysian Borneo. Deforestation and associated environmental and population changes have been hypothesized as main drivers of this apparent emergence. We gathered village-level data for P. knowlesi incidence for the districts of Kudat and Kota Marudu in Sabah state, Malaysia, for 2008–2012. We adjusted malaria records from routine reporting systems to reflect the diagnostic uncertainty of microscopy for P. knowlesi. We also developed negative binomial spatial autoregressive models to assess potential associations between P. knowlesi incidence and environmental variables derived from satellite-based remote-sensing data. Marked spatial heterogeneity in P. knowlesi incidence was observed, and village-level numbers of P. knowlesi cases were positively associated with forest cover and historical forest loss in surrounding areas. These results suggest the likelihood that deforestation and associated environmental changes are key drivers in P. knowlesi transmission in these areas. PMID:26812373

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

    PubMed

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

    2014-02-01

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

  15. Effect of artesunate based combination therapy with homeopathic medicine china on liver and kidney of Plasmodium berghei infected mice.

    PubMed

    Rajan, A; Bagai, U; Chandel, S

    2013-04-01

    Present study has been undertaken to evaluate antimalarial potential and safety of artesunate based combination therapy with homeopathic medicine china (ϕ/30 potency) against Plasmodium berghei (NK-65), a lethal rodent malaria parasite. In combination therapy, the oral administration of artesunate (100 mg/kg) + china ϕ/30 proved to be highly efficacious as it completely cleared the blood stage infection. During the follow up period up to day 28, no recrudescence was observed and the survival rate was 100 %. Combination did not disturb the normal functioning of liver and kidney, as evident from the normal activity of ALP (190.5 ± 0.2 and 174.2 ± 9.12 IU/l), level of bilirubin (0.6 ± 0.33 and 0.73 ± 0.1 mg/dl), urea (28 ± 0.51 and 29.1 ± 0.03 mg/dl) and creatinine (0.9 ± 0.62 and 1.1 ± 0.1 mg/dl) in serum of treated mice on day 7 and 28 respectively. Present study points to better efficacy of china as an alternative drug partner in combination to enhance antimalarial efficacy of artesunate without affecting the liver and kidney functions of P. berghei infected BALB/c mice. PMID:24431543

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

    PubMed

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

    2015-12-01

    Large datasets are often not amenable to analysis using traditional single-step approaches. Here, our general objective was to apply imputation techniques, principal component analysis (PCA), elastic net and generalized linear models to a large dataset in a systematic approach to extract the most meaningful predictors for a health outcome. We extracted predictors for Plasmodium falciparum infection, from a large covariate dataset while facing limited numbers of observations, using data from the People, Animals, and their Zoonoses (PAZ) project to demonstrate these techniques: data collected from 415 homesteads in western Kenya, contained over 1500 variables that describe the health, environment, and social factors of the humans, livestock, and the homesteads in which they reside. The wide, sparse dataset was simplified to 42 predictors of P. falciparum malaria infection and wealth rankings were produced for all homesteads. The 42 predictors make biological sense and are supported by previous studies. This systematic data-mining approach we used would make many large datasets more manageable and informative for decision-making processes and health policy prioritization. PMID:25876816

  17. A Defect in Interleukin-10 Leads to Enhanced Malarial Disease in Plasmodium chabaudi chabaudi Infection in Mice

    PubMed Central

    Li, Ching; Corraliza, Inés; Langhorne, Jean

    1999-01-01

    Infection of interleukin-10 (IL-10)-nonexpressing (IL-10−/−) mice with Plasmodium chabaudi chabaudi (AS) leads to exacerbated pathology in female mice and death in a proportion of them. Hypoglycemia, hypothermia, and loss in body weight were significantly greater in female IL-10−/− mice than in male knockout mice and all wild-type (WT) mice during the acute phase of infection. At this time, both female and male IL-10−/− mice produced more gamma interferon (IFN-γ), tumor necrosis factor alpha (TNF-α), and IL-12p40 mRNA than their respective WT counterparts. Inactivation of IFN-γ in IL-10−/− mice by the injection of anti-IFN-γ antibodies or by the generation of IL-10−/− IFN-γ receptor−/− double-knockout mice resulted in reduced mortality but did not affect body weight, temperature, or blood glucose levels. The data suggest that IFN-γ-independent pathways may be responsible for these pathological features of P. chabaudi malaria and may be due to direct stimulation of TNF-α by the parasite. Since male and female knockout mice both produce more inflammatory cytokines than their WT counterparts, it is likely that the mortality seen in females is due to the nature or magnitude of the response to these cytokines rather than the amount of IFN-γ or TNF-α produced. PMID:10456884

  18. Use of self-assembling GFP to determine protein topology and compartmentalisation in the Plasmodium falciparum-infected erythrocyte.

    PubMed

    Külzer, Simone; Petersen, Wiebke; Baser, Avni; Mandel, Katharina; Przyborski, Jude M

    2013-02-01

    In recent years, and largely supported by the increasing use of transfection technology, much research attention has been given to protein trafficking in the Plasmodium falciparum infected red blood cell. By expression of fluorescent reporter proteins, much information has been gained on both the signals and mechanisms directing proteins to their correct sub-cellular localisation within the parasite and infected host cell. Generally however, verification of the observed fluorescent phenotype is carried out using more traditional techniques such as co-immunofluorescence, protease protection, and cell fractionation followed by Western blot. Here we apply a self-assembling split GFP (saGFP) system and show that this can be used to determine both membrane topology and compartmentalisation using transfection technology alone. As an example, we verify the topology of an ER membrane protein, hDer1-1, and of an exported parasite Hsp40 co-chaperone, PFE55. Additionally, we can demonstrate that this system has the potential to be applied to analysis of organellar proteins. PMID:23271009

  19. Impact of different strategies to control Plasmodium infection and anaemia on the island of Bioko (Equatorial Guinea)

    PubMed Central

    Pardo, Gema; Angel Descalzo, Miguel; Molina, Laura; Custodio, Estefanía; Lwanga, Magdalena; Mangue, Catalina; Obono, Jaquelina; Nchama, Araceli; Roche, Jesús; Benito, Agustín; Cano, Jorge

    2006-01-01

    Background On the island of Bioko (Equatorial Guinea), insecticide-treated nets (ITNs) have been the main tool used to control malaria over the last 13 years. In 2004, started an indoor residual spraying (IRS) campaign to control malaria. The purpose of this study is to asses the impact of the two control strategies on the island of Bioko (Equatorial Guinea), with regards to Plasmodium infection and anaemia in the children under five years of age. Methods Two transversal studies, the first one prior to the start of the IRS campaign and the second one year later. Sampling was carried out by stratified clusters. Malaria infection was measured by means of thick and thin film, and the packed cell volume (PCV) percentage. Data related to ITN use and information regarding IRS were collected. The Pearson's chi-square and logistic regression statistical tests were used to calculate odds ratios (OR) Results In the first survey, 168 children were sampled and 433 children in the second one. The prevalence of infection was 40% in 2004, and significantly lower at 21.7% in 2005. PCV was 41% and 39%, respectively. 58% of the children surveyed in 2004 and 44.3% in 2005 had slept under an ITN. 78% of the dwellings studied in 2005 had been sprayed. In the 2005 survey, sleeping without a mosquito net meant a risk of infection 3 times greater than sleeping protected with a net hanged correctly and with no holes (p < 0.05). Conclusion IRS and ITNs have proven to be effective control strategies on the island of Bioko. The choice of one or other strategy is, above all, a question of operational feasibility and availability of local resources. PMID:16460558

  20. Bacillus Calmette-Guérin-inoculation at different time points influences the outcome of C57BL/6 mice infected with Plasmodium chabaudi chabaudi AS.

    PubMed

    Cao, Dong-Hua; Wang, Ji-Chun; Liu, Jun; Du, Yun-Ting; Cui, Li-Wang; Cao, Ya-Ming

    2016-01-01

    Bacillus Calmette-Guérin (BCG) is an attenuated Mycobacterium tuberculosis vaccine. We performed a series of co-infection experiments with BCG-Plasmodium chabaudi chabaudi Landau, 1965 AS using C57BL/6 mice to analyse whether BCG can affect the development of protective immunity to infection with Plasmodium spp. and the mechanism of this protection. We divided mice into four groups: BCG-inoculation 4 weeks prior to P. c. chabaudi AS infection (B-4w-Pc); simultaneous BCG-inoculation and P. c. chabaudi AS infection (Pc+B); BCG-inoculation 3 days post P. c. chabaudi AS (Pc-3-B) infection; and mono-P. c. chabaudi AS infection as control (Pc). The parasitemia level in the B-4w-Pc group was noticeably higher than control group at 6-19 days post infection (dpi). Compared with the control group, the proportion of CD4(+)CD69(+) T cells was significantly reduced 5, 8 and 12 dpi, but the proportion of CD4(+)CD25(+)Foxp3(+) Tregs was significantly increased in the B-4w-Pc group on 5 and 8 dpi. The B-4w-Pc group also demonstrated reduced levels of IFN-γ and TNF-α on 5 and 8 dpi and significantly elevated level of IL-10 on 12 dpi. There were significantly fewer mDCs (CD11c(+)CD11b(+)) and pDCs (CD11c(+)B220(+)) in the B-4w-Pc group than the control group at all the time points post infection and the expression of MHC II was noticeably reduced on day 8 pi. Our findings confirmed that BCG inoculation prior to Plasmodium infection resulted in excessive activation and proliferation of Tregs and upregulation of anti-inflammatory mediators, which inhibited establishment of a Th1-dominant immune response during the early stages of Plasmodium infection by inhibiting dendritive cells response. BCG inoculation prior to P. c. chabaudi AS infection may contribute to overgrowth of parasites as well as mortality in mice. PMID:27188912

  1. Differential susceptibilities of Anopheles albimanus and Anopheles pseudopunctipennis to infections with coindigenous Plasmodium vivax variants VK210 and VK247 in southern Mexico.

    PubMed

    Gonzalez-Ceron, L; Rodriguez, M H; Nettel, J C; Villarreal, C; Kain, K C; Hernandez, J E

    1999-01-01

    The susceptibilities to coindigenous Plasmodium vivax of colonized Anopheles albimanus and Anopheles pseudopunctipennis from southern Mexico were investigated by simultaneous feeding with infected blood obtained from patients. The genes encoding circumsporozoite protein variant types (VK210 and VK247) in blood samples were determined by PCR and oligonucleotide probe hybridization. A. albimanus was more susceptible to VK210, and A. pseudopunctipennis was more susceptible to VK247. PMID:9864243

  2. Maladjusted host immune responses induce experimental cerebral malaria-like pathology in a murine Borrelia and Plasmodium co-infection model.

    PubMed

    Normark, Johan; Nelson, Maria; Engström, Patrik; Andersson, Marie; Björk, Rafael; Moritz, Thomas; Fahlgren, Anna; Bergström, Sven

    2014-01-01

    In the Plasmodium infected host, a balance between pro- and anti-inflammatory responses is required to clear the parasites without inducing major host pathology. Clinical reports suggest that bacterial infection in conjunction with malaria aggravates disease and raises both mortality and morbidity in these patients. In this study, we investigated the immune responses in BALB/c mice, co-infected with Plasmodium berghei NK65 parasites and the relapsing fever bacterium Borrelia duttonii. In contrast to single infections, we identified in the co-infected mice a reduction of L-Arginine levels in the serum. It indicated diminished bioavailability of NO, which argued for a dysfunctional endothelium. Consistent with this, we observed increased sequestration of CD8+ cells in the brain as well over expression of ICAM-1 and VCAM by brain endothelial cells. Co-infected mice further showed an increased inflammatory response through IL-1β and TNF-α, as well as inability to down regulate the same through IL-10. In addition we found loss of synchronicity of pro- and anti-inflammatory signals seen in dendritic cells and macrophages, as well as increased numbers of regulatory T-cells. Our study shows that a situation mimicking experimental cerebral malaria (ECM) is induced in co-infected mice due to loss of timing and control over regulatory mechanisms in antigen presenting cells. PMID:25075973

  3. Maladjusted Host Immune Responses Induce Experimental Cerebral Malaria-Like Pathology in a Murine Borrelia and Plasmodium Co-Infection Model

    PubMed Central

    Normark, Johan; Nelson, Maria; Engström, Patrik; Andersson, Marie; Björk, Rafael; Moritz, Thomas; Fahlgren, Anna; Bergström, Sven

    2014-01-01

    In the Plasmodium infected host, a balance between pro- and anti-inflammatory responses is required to clear the parasites without inducing major host pathology. Clinical reports suggest that bacterial infection in conjunction with malaria aggravates disease and raises both mortality and morbidity in these patients. In this study, we investigated the immune responses in BALB/c mice, co-infected with Plasmodium berghei NK65 parasites and the relapsing fever bacterium Borrelia duttonii. In contrast to single infections, we identified in the co-infected mice a reduction of L-Arginine levels in the serum. It indicated diminished bioavailability of NO, which argued for a dysfunctional endothelium. Consistent with this, we observed increased sequestration of CD8+ cells in the brain as well over expression of ICAM-1 and VCAM by brain endothelial cells. Co-infected mice further showed an increased inflammatory response through IL-1β and TNF-α, as well as inability to down regulate the same through IL-10. In addition we found loss of synchronicity of pro- and anti-inflammatory signals seen in dendritic cells and macrophages, as well as increased numbers of regulatory T-cells. Our study shows that a situation mimicking experimental cerebral malaria (ECM) is induced in co-infected mice due to loss of timing and control over regulatory mechanisms in antigen presenting cells. PMID:25075973

  4. 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

  5. Are mixed-species bird flocks stable through two decades?

    PubMed

    Martínez, Ari E; Gomez, Juan P

    2013-03-01

    The stability of tropical systems has been hypothesized to explain the evolution of complex behavioral interactions among species. We evaluate the degree to which one highly evolved social system, mixed-species flocks, are stable in space and time in French Guiana, where flocks were characterized 17 years apart. These flocks are led by alarm-calling "sentinels," which may benefit from food flushed by other "beater" species. Using null models, we found that flock roost sites, home range overlap, and composition were more similar than expected by chance; home ranges were nearly identical between the two time periods. Such extremely stable conditions may be essential for the evolution and maintenance of the sentinel-beater system that appears to characterize some flocks. These results may reflect an evolutionarily stable strategy among potentially interdependent species within mixed-species flocks, where home ranges contribute to stability by being far larger than the most common local disturbances in the forest. PMID:23448892

  6. Testosterone-induced permanent changes of hepatic gene expression in female mice sustained during Plasmodium chabaudi malaria infection.

    PubMed

    Delić, Denis; Gailus, Nicole; Vohr, Hans-Werner; Dkhil, Mohamed; Al-Quraishy, Saleh; Wunderlich, Frank

    2010-12-01

    Testosterone has been previously shown to induce persistent susceptibility to Plasmodium chabaudi malaria in otherwise resistant female C57BL/6 mice. Here, we investigate as to whether this conversion coincides with permanent changes of hepatic gene expression profiles. Female mice aged 10-12 weeks were treated with testosterone for 3 weeks; then, testosterone treatment was discontinued for 12 weeks before challenging with 10⁶ P. chabaudi-infected erythrocytes. Hepatic gene expression was examined after 12 weeks of testosterone withdrawal and after subsequent infection with P. chabaudi at peak parasitemia, using Affymetrix microarrays with 22 ,690 probe sets representing 14, 000 genes. The expression of 54 genes was found to be permanently changed by testosterone, which remained changed during malaria infection. Most genes were involved in liver metabolism: the female-prevalent genes Cyp2b9, Cyp2b13, Cyp3a41, Cyp3a44, Fmo3, Sult2a2, Sult3a1, and BC014805 were repressed, while the male-prevalent genes Cyp2d9, Cyp7b1, Cyp4a10, Ugt2b1, Ugt2b38, Hsd3b5, and Slco1a1 were upregulated. Genes encoding different nuclear receptors were not persistently changed. Moreover, testosterone induced persistent upregulation of genes involved in hepatocellular carcinoma such as Lama3 and Nox4, whereas genes involved in immune response such as Ifnγ and Igk-C were significantly decreased. Our data provide evidence that testosterone is able to induce specific and robust long-term changes of gene expression profiles in the female mouse liver. In particular, those changes, which presumably indicate masculinized liver metabolism and impaired immune response, may be critical for the testosterone-induced persistent susceptibility of mice to P. chabaudi malaria. PMID:20844152

  7. Redox Conductivity of Current-Producing Mixed Species Biofilms

    PubMed Central

    Fan, Yanzhen; Liu, Hong

    2016-01-01

    While most biological materials are insulating in nature, efficient extracellular electron transfer is a critical property of biofilms associated with microbial electrochemical systems and several microorganisms are capable of establishing conductive aggregates and biofilms. Though construction of these conductive microbial networks is an intriguing and important phenomenon in both natural and engineered systems, few studies have been published related to conductive biofilms/aggregates and their conduction mechanisms, especially in mixed-species environments. In the present study, current-producing mixed species biofilms exhibited high conductivity across non-conductive gaps. Biofilm growth observed on the inactive electrode contributed to overall power outputs, suggesting that an electrical connection was established throughout the biofilm assembly. Electrochemical gating analysis of the biofilms over a range of potentials (-600–200 mV, vs. Ag/AgCl) resulted in a peak-manner response with maximum conductance of 3437 ± 271 μS at a gate potential of -360 mV. Following removal of the electron donor (acetate), a 96.6% decrease in peak conductivity was observed. Differential responses observed in the absence of an electron donor and over varying potentials suggest a redox driven conductivity mechanism in mixed-species biofilms. These results demonstrated significant differences in biofilm development and conductivity compared to previous studies using pure cultures. PMID:27159497

  8. 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

  9. Artemisinin-Resistant Plasmodium falciparum Parasites Exhibit Altered Patterns of Development in Infected Erythrocytes

    PubMed Central

    Hott, Amanda; Casandra, Debora; Sparks, Kansas N.; Morton, Lindsay C.; Castanares, Geocel-Grace; Rutter, Amanda

    2015-01-01

    Artemisinin derivatives are used in combination with other antimalarial drugs for treatment of multidrug-resistant malaria worldwide. Clinical resistance to artemisinin recently emerged in southeast Asia, yet in vitro phenotypes for discerning mechanism(s) of resistance remain elusive. Here, we describe novel phenotypic resistance traits expressed by artemisinin-resistant Plasmodium falciparum. The resistant parasites exhibit altered patterns of development that result in reduced exposure to drug at the most susceptible stage of development in erythrocytes (trophozoites) and increased exposure in the most resistant stage (rings). In addition, a novel in vitro delayed clearance assay (DCA) that assesses drug effects on asexual stages was found to correlate with parasite clearance half-life in vivo as well as with mutations in the Kelch domain gene associated with resistance (Pf3D7_1343700). Importantly, all of the resistance phenotypes were stable in cloned parasites for more than 2 years without drug pressure. The results demonstrate artemisinin-resistant P. falciparum has evolved a novel mechanism of phenotypic resistance to artemisinin drugs linked to abnormal cell cycle regulation. These results offer insights into a novel mechanism of drug resistance in P. falciparum and new tools for monitoring the spread of artemisinin resistance. PMID:25779582

  10. Trafficking of STEVOR to the Maurer's clefts in Plasmodium falciparum-infected erythrocytes

    PubMed Central

    Przyborski, Jude M; Miller, Susanne K; Pfahler, Judith M; Henrich, Philipp P; Rohrbach, Petra; Crabb, Brendan S; Lanzer, Michael

    2005-01-01

    The human malarial parasite Plasmodium falciparum exports proteins to destinations within its host erythrocyte, including cytosol, surface and membranous profiles of parasite origin termed Maurer's clefts. Although several of these exported proteins are determinants of pathology and virulence, the mechanisms and trafficking signals underpinning protein export are largely uncharacterized—particularly for exported transmembrane proteins. Here, we have investigated the signals mediating trafficking of STEVOR, a family of transmembrane proteins located at the Maurer's clefts and believed to play a role in antigenic variation. Our data show that, apart from a signal sequence, a minimum of two addition signals are required. This includes a host cell targeting signal for export to the host erythrocyte and a transmembrane domain for final sorting to Maurer's clefts. Biochemical studies indicate that STEVOR traverses the secretory pathway as an integral membrane protein. Our data suggest general principles for transport of transmembrane proteins to the Maurer's clefts and provide new insights into protein sorting and trafficking processes in P. falciparum. PMID:15961998

  11. Variation in haematological parameters in children less than five years of age with asymptomatic Plasmodium infection: implication for malaria field studies

    PubMed Central

    Gansane, Adama; Ouedraogo, Issa Nebie; Henry, Noelie Bere; Soulama, Issiaka; Ouedraogo, Esperance; Yaro, Jean-Baptiste; Diarra, Amidou; Benjamin, Sombie; Konate, Amadou Tidiani; Tiono, Alfred; Sirima, Sodiomon Bienvenu

    2013-01-01

    During the season of high malaria transmission, most children are infected by Plasmodium, which targets red blood cells (RBCs), affecting haematological parameters. To describe these variations, we examined the haematological profiles of two groups of children living in a malaria-endemic area. A cross-sectional survey was conducted at the peak of the malaria transmission season in a rural area of Burkina Faso. After informed consent and clinical examination, blood samples were obtained from the participants for malaria diagnosis and a full blood count. Of the 414 children included in the analysis, 192 were not infected with Plasmodium, whereas 222 were asymptomatic carriers of Plasmodium infection. The mean age of the infected children was 41.8 months (range of 26.4-57.2) compared to 38.8 months (range of 22.4-55.2) for the control group (p = 0.06). The asymptomatic infected children tended to have a significantly lower mean haemoglobin level (10.8 g/dL vs. 10.4 g/dL; p < 0.001), mean lymphocyte count (4592/µL vs. 5141/µL; p = 0.004), mean platelet count (266 x 103/µL vs. 385 x 103/µL; p < 0.001) and mean RBC count (4.388 x 106/µL vs. 4.158 x 106/µL; p < 0.001) and a higher mean monocyte count (1403/µL vs. 1192/µL; p < 0.001) compared to the control group. Special attention should be applied when interpreting haematological parameters and evaluating immune responses in asymptomatic infected children living in malaria-endemic areas and enrolled in vaccine trials. PMID:23903982

  12. Effects of malaria (Plasmodium relicturm) on activity budgets of experimentally-infected juvenile Apapane (Himatione sanquinea)

    USGS Publications Warehouse

    Yorinks, N.; Atkinson, C.T.

    2000-01-01

    We used behavioral, physiological, and parasitological measures to document effects of acute malarial infections on activity budgets of experimentally infected juvenile Apapane (Himatione sanguinea). Five of eight birds died within 20 to 32 days after exposure to a single infective mosquito bite. Infected Apapane devoted less time to locomotory activities involving flight, walking or hopping, and stationary activities such as singing, preening, feeding, and probing. The amount of time spent sitting was positively correlated with parasitemia and increased dramatically after infection and between treatment and control groups. Birds that succumbed to infection experienced a significant loss of body mass and subcutaneous fat, whereas surviving Apapane were better able to maintain body condition and fat levels. When rechallenged with the parasite five months after initial infection, surviving birds experienced no increase in parasitemia, indicating that they had become immune to reinfection. Regardless of the outcome, infected birds experienced acute illness that would have left them unable to forage or to escape from predators in the wild.

  13. Fractionation of Plasmodium-infected human red blood cells to study protein trafficking.

    PubMed

    Külzer, Simone; Bittl, Verena; Przyborski, Jude M

    2015-01-01

    Subcellular fractionation is a valuable tool to follow protein traffic between cellular compartments. Here we detail a procedure for fractionating erythrocytes infected with the human malaria parasite P. falciparum using the bacterial pore-forming protein Streptolysin O (SLO). Additionally we describe an experimental protocol to determine protein topology by carrying out a protease protection assay on SLO-lysed infected erythrocytes. PMID:25702109

  14. Antibody responses to surface antigens of Plasmodium falciparum gametocyte-infected erythrocytes and their relation to gametocytaemia.

    PubMed

    Dinko, B; King, E; Targett, G A T; Sutherland, C J

    2016-06-01

    An essential element for continuing transmission of Plasmodium falciparum is the availability of mature gametocytes in human peripheral circulation for uptake by mosquitoes. Natural immune responses to circulating gametocytes may play a role in reducing transmission from humans to mosquitoes. Here, antibody recognition of the surface of mature intra-erythrocytic gametocytes produced either by a laboratory-adapted parasite, 3D7, or by a recent clinical isolate of Kenyan origin (HL1204), was evaluated longitudinally in a cohort of Ghanaian school children by flow cytometry. This showed that a proportion of children exhibited antibody responses that recognized gametocyte surface antigens on one or both parasite lines. A subset of the children maintained detectable anti-gametocyte surface antigen (GSA) antibody levels during the 5 week study period. There was indicative evidence that children with anti-GSA antibodies present at enrolment were less likely to have patent gametocytaemia at subsequent visits (odds ratio = 0·29, 95% CI 0·06-1·05; P = 0·034). Our data support the existence of antigens on the surface of gametocyte-infected erythrocytes, but further studies are needed to confirm whether antibodies against them reduce gametocyte carriage. The identification of GSA would allow their evaluation as potential anti-gametocyte vaccine candidates and/or biomarkers for gametocyte carriage. PMID:27084060

  15. A Randomized Comparison of Chloroquine Versus Dihydroartemisinin-Piperaquine for the Treatment of Plasmodium vivax Infection in Vietnam.

    PubMed

    Thuan, Phung Duc; Ca, Nguyen Thuy Nha; Van Toi, Pham; Nhien, Nguyen Thanh Thuy; Thanh, Ngo Viet; Anh, Nguyen Duc; Phu, Nguyen Hoan; Thai, Cao Quang; Thai, Le Hong; Hoa, Nhu Thi; Dong, Le Thanh; Loi, Mai Anh; Son, Do Hung; Khanh, Tran Tinh Ngoc; Dolecek, Christiane; Nhan, Ho Thi; Wolbers, Marcel; Thwaites, Guy; Farrar, Jeremy; White, Nicholas J; Hien, Tran Tinh

    2016-04-01

    A total of 128 Vietnamese patients with symptomatic Plasmodium vivax mono-infections were enrolled in a prospective, open-label, randomized trial to receive either chloroquine or dihydroartemisinin-piperaquine (DHA-PPQ). The proportions of patients with adequate clinical and parasitological responses were 47% in the chloroquine arm (31 of 65 patients) and 66% in the DHA-PPQ arm (42 of 63 patients) in the Kaplan-Meier intention-to-treat analysis (absolute difference 19%, 95% confidence interval = 0-37%), thus establishing non-inferiority of DHA-PPQ. Fever clearance time (median 24 versus 12 hours,P= 0.02), parasite clearance time (median 36 versus 18 hours,P< 0.001), and parasite clearance half-life (mean 3.98 versus 1.80 hours,P< 0.001) were all significantly shorter in the DHA-PPQ arm. All cases of recurrent parasitemia in the chloroquine arm occurred from day 33 onward, with corresponding whole blood chloroquine concentration lower than 100 ng/mL in all patients. Chloroquine thus remains efficacious for the treatment of P. vivax malaria in southern Vietnam, but DHA-PPQ provides more rapid symptomatic and parasitological recovery. PMID:26856909

  16. A Randomized Comparison of Chloroquine versus Dihydroartemisinin–Piperaquine for the Treatment of Plasmodium vivax Infection in Vietnam

    PubMed Central

    Thuan, Phung Duc; Ca, Nguyen Thuy Nha; Van Toi, Pham; Nhien, Nguyen Thanh Thuy; Thanh, Ngo Viet; Anh, Nguyen Duc; Phu, Nguyen Hoan; Thai, Cao Quang; Hong Thai, Le; Hoa, Nhu Thi; Thanh Dong, Le; Loi, Mai Anh; Son, Do Hung; Khanh, Tran Tinh Ngoc; Dolecek, Christiane; Nhan, Ho Thi; Wolbers, Marcel; Thwaites, Guy; Farrar, Jeremy; White, Nicholas J.; Hien, Tran Tinh

    2016-01-01

    A total of 128 Vietnamese patients with symptomatic Plasmodium vivax mono-infections were enrolled in a prospective, open-label, randomized trial to receive either chloroquine or dihydroartemisinin–piperaquine (DHA-PPQ). The proportions of patients with adequate clinical and parasitological responses were 47% in the chloroquine arm (31 of 65 patients) and 66% in the DHA-PPQ arm (42 of 63 patients) in the Kaplan–Meier intention-to-treat analysis (absolute difference 19%, 95% confidence interval = 0–37%), thus establishing non-inferiority of DHA-PPQ. Fever clearance time (median 24 versus 12 hours, P = 0.02), parasite clearance time (median 36 versus 18 hours, P < 0.001), and parasite clearance half-life (mean 3.98 versus 1.80 hours, P < 0.001) were all significantly shorter in the DHA-PPQ arm. All cases of recurrent parasitemia in the chloroquine arm occurred from day 33 onward, with corresponding whole blood chloroquine concentration lower than 100 ng/mL in all patients. Chloroquine thus remains efficacious for the treatment of P. vivax malaria in southern Vietnam, but DHA-PPQ provides more rapid symptomatic and parasitological recovery. PMID:26856909

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

    NASA Astrophysics Data System (ADS)

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

    2012-08-01

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

  18. 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.

  19. Automated classification of Plasmodium sporozoite movement patterns reveals a shift towards productive motility during salivary gland infection.

    PubMed

    Hegge, Stephan; Kudryashev, Mikhail; Smith, Ashley; Frischknecht, Friedrich

    2009-06-01

    The invasive stages of malaria and other apicomplexan parasites use a unique motility machinery based on actin, myosin and a number of parasite-specific proteins to invade host cells and tissues. The crucial importance of this motility machinery at several stages of the life cycle of these parasites makes the individual components potential drug targets. The different stages of the malaria parasite exhibit strikingly diverse movement patterns, likely reflecting the varied needs to achieve successful invasion. Here, we describe a Tool for Automated Sporozoite Tracking (ToAST) that allows the rapid simultaneous analysis of several hundred motile Plasmodium sporozoites, the stage of the malaria parasite transmitted by the mosquito. ToAST reliably categorizes different modes of sporozoite movement and can be used for both tracking changes in movement patterns and comparing overall movement parameters, such as average speed or the persistence of sporozoites undergoing a certain type of movement. This allows the comparison of potentially small differences between distinct parasite populations and will enable screening of drug libraries to find inhibitors of sporozoite motility. Using ToAST, we find that isolated sporozoites change their movement patterns towards productive motility during the first week after infection of mosquito salivary glands. PMID:19455538

  20. Plasmodium-infected erythrocytes (pRBC) induce endothelial cell apoptosis via a heme-mediated signaling pathway

    PubMed Central

    Liu, Mingli; Dickinson-Copeland, Carmen; Hassana, Salifu; Stiles, Jonathan K

    2016-01-01

    Heme is cytotoxic to the plasmodium parasite, which converts it to an insoluble crystalline form called hemozoin (malaria pigment) in erythrocytes during replication. The increased serum levels of free heme cause tissue damage, activation of microvascular endothelial and glial cells, focal inflammation, activation of apoptotic pathways, and neuronal tissue damage. Several hypotheses have been proposed to explain how these causative factors exacerbate fatal malaria. However, none of them fully explain the detailed mechanisms leading to the high morbidity and mortality associated with malaria. We have previously reported that heme-induced brain microvascular endothelial cell (HBVEC) apoptosis is a major contributor to severe malaria pathogenesis. Here, we hypothesized that heme (at clinically relevant levels) induces inflammation and apoptosis in HBVEC, a process that is mediated by independent proinflammatory and proapoptotic signaling pathways. In this study, we determined the key signaling molecules associated with heme-mediated apoptosis in HBVEC in vitro using RT2 profiler polymerase chain reaction array technology and confirmed results using immunostaining techniques. While several expressed genes in HBVEC were altered upon heme stimulation, we determined that the apoptotic effects of heme were mediated through p73 (tumor protein p73). The results provide an opportunity to target heme-mediated apoptosis therapeutically in malaria-infected individuals. PMID:27042002

  1. Visualizing the 3D Architecture of Multiple Erythrocytes Infected with Plasmodium at Nanoscale by Focused Ion Beam-Scanning Electron Microscopy

    PubMed Central

    Soares Medeiros, Lia Carolina; De Souza, Wanderley; Jiao, Chengge; Barrabin, Hector; Miranda, Kildare

    2012-01-01

    Different methods for three-dimensional visualization of biological structures have been developed and extensively applied by different research groups. In the field of electron microscopy, a new technique that has emerged is the use of a focused ion beam and scanning electron microscopy for 3D reconstruction at nanoscale resolution. The higher extent of volume that can be reconstructed with this instrument represent one of the main benefits of this technique, which can provide statistically relevant 3D morphometrical data. As the life cycle of Plasmodium species is a process that involves several structurally complex developmental stages that are responsible for a series of modifications in the erythrocyte surface and cytoplasm, a high number of features within the parasites and the host cells has to be sampled for the correct interpretation of their 3D organization. Here, we used FIB-SEM to visualize the 3D architecture of multiple erythrocytes infected with Plasmodium chabaudi and analyzed their morphometrical parameters in a 3D space. We analyzed and quantified alterations on the host cells, such as the variety of shapes and sizes of their membrane profiles and parasite internal structures such as a polymorphic organization of hemoglobin-filled tubules. The results show the complex 3D organization of Plasmodium and infected erythrocyte, and demonstrate the contribution of FIB-SEM for the obtainment of statistical data for an accurate interpretation of complex biological structures. PMID:22432024

  2. Return to sender: use of Plasmodium ER retrieval sequences to study protein transport in the infected erythrocyte and predict putative ER protein families.

    PubMed

    Külzer, Simone; Gehde, Nina; Przyborski, Jude M

    2009-06-01

    We have investigated how knowledge of endoplasmic reticulum (ER) retrieval signals can be used to study specific trafficking pathways in the malaria-infected erythrocyte. We show that addition of various lumenal ER retrieval signals to soluble green fluorescent protein (GFP) chimaera causes retrieval of the fusion protein in the parasite's ER. In contrast, adding these signals to the C-terminus of a membrane bound protein does not affect its eventual sub-cellular localization. This demonstrates proof of principle that ER retrieval signals can be used to study the solubility state of Plasmodium falciparum proteins during their transport to the host erythrocyte. Furthermore, using our knowledge of ER retrieval signals, we identify Plasmodium ER protein families and assign putative functions to them. PMID:19294420

  3. Placental Plasmodium falciparum malaria infection: Operational accuracy of HRP2 rapid diagnostic tests in a malaria endemic setting

    PubMed Central

    2011-01-01

    Background Malaria has a negative effect on the outcome of pregnancy. Pregnant women are at high risk of severe malaria and severe haemolytic anaemia, which contribute 60-70% of foetal and perinatal losses. Peripheral blood smear microscopy under-estimates sequestered placental infections, therefore malaria rapid diagnostic tests (RDTs) detecting histidine rich protein-2 antigen (HRP-2) in peripheral blood are a potential alternative. Methods HRP-2 RDTs accuracy in detecting malaria in pregnancy (MIP >28 weeks gestation) and placental Plasmodium falciparum malaria (after childbirth) were conducted using Giemsa microscopy and placental histopathology respectively as the reference standard. The study was conducted in Mbale Hospital, using the midwives to perform and interpret the RDT results. Discordant results samples were spot checked using PCR techniques. Results Among 433 febrile women tested, RDTs had a sensitivity of 96.8% (95% CI 92-98.8), specificity of 73.5% (95% CI 67.8-78.6), a positive predictive value (PPV) of 68.0% (95% CI 61.4-73.9), and negative predictive value (NPV) of 97.5% (95% CI 94.0-99.0) in detecting peripheral P. falciparum malaria during pregnancy. At delivery, in non-symptomatic women, RDTs had a 80.9% sensitivity (95% CI 57.4-93.7) and a 87.5% specificity (95%CI 80.9-92.1), PPV of 47.2% (95% CI 30.7-64.2) and NPV of 97.1% (95% CI 92.2-99.1) in detecting placental P. falciparum infections among 173 samples. At delivery, 41% of peripheral infections were detected by microscopy without concurrent placental infection. The combination of RDTs and microscopy improved the sensitivity to 90.5% and the specificity to 98.4% for detecting placental malaria infection (McNemar's X 2> 3.84). RDTs were not superior to microscopy in detecting placental infection (McNemar's X 2< 3.84). Presence of malaria in pregnancy and active placental malaria infection were 38% and 12% respectively. Placental infections were associated with poor pregnancy outcome [pre

  4. A High Resolution Case Study of a Patient with Recurrent Plasmodium vivax Infections Shows That Relapses Were Caused by Meiotic Siblings

    PubMed Central

    Bright, Andrew Taylor; Manary, Micah J.; Tewhey, Ryan; Arango, Eliana M.; Wang, Tina; Schork, Nicholas J.; Yanow, Stephanie K.; Winzeler, Elizabeth A.

    2014-01-01

    Plasmodium vivax infects a hundred million people annually and endangers 40% of the world's population. Unlike Plasmodium falciparum, P. vivax parasites can persist as a dormant stage in the liver, known as the hypnozoite, and these dormant forms can cause malaria relapses months or years after the initial mosquito bite. Here we analyze whole genome sequencing data from parasites in the blood of a patient who experienced consecutive P. vivax relapses over 33 months in a non-endemic country. By analyzing patterns of identity, read coverage, and the presence or absence of minor alleles in the initial polyclonal and subsequent monoclonal infections, we show that the parasites in the three infections are likely meiotic siblings. We infer that these siblings are descended from a single tetrad-like form that developed in the infecting mosquito midgut shortly after fertilization. In this natural cross we find the recombination rate for P. vivax to be 10 kb per centimorgan and we further observe areas of disequilibrium surrounding major drug resistance genes. Our data provide new strategies for studying multiclonal infections, which are common in all types of infectious diseases, and for distinguishing P. vivax relapses from reinfections in malaria endemic regions. This work provides a theoretical foundation for studies that aim to determine if new or existing drugs can provide a radical cure of P. vivax malaria. PMID:24901334

  5. 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

  6. Co-endemicity of Plasmodium falciparum and Intestinal Helminths Infection in School Age Children in Rural Communities of Kwara State Nigeria

    PubMed Central

    Adedoja, Ayodele; Tijani, Bukola Deborah; Akanbi, Ajibola A.; Ojurongbe, Taiwo A.; Adeyeba, Oluwaseyi A.; Ojurongbe, Olusola

    2015-01-01

    Background Malaria and intestinal helminths co-infection are major public health problems particularly among school age children in Nigeria. However the magnitude and possible interactions of these infections remain poorly understood. This study determined the prevalence, impact and possible interaction of Plasmodium falciparum and intestinal helminths co-infection among school children in rural communities of Kwara State, Nigeria. Methods Blood, urine and stool samples were collected from 1017 primary school pupils of ages 4–15 years. Stool samples were processed using both Kato-Katz and formol-ether concentration techniques and microscopically examined for intestinal helminths infection. Urine samples were analyzed using sedimentation method for Schistosoma haematobium. Plasmodium falciparum was confirmed by microscopy using thick and thin blood films methods and packed cell volume (PCV) was determined using hematocrit reader. Univariate analysis and chi-square statistical tests were used to analyze the data. Results Overall, 61.2% of all school children had at least an infection of either P. falciparum, S. haematobium, or intestinal helminth. S. haematobium accounted for the largest proportion (44.4%) of a single infection followed by P. falciparum (20.6%). The prevalence of malaria and helminth co-infection in the study was 14.4%. Four species of intestinal helminths were recovered from the stool samples and these were hookworm (22.5%), Hymenolepis species (9.8%), Schistosoma mansoni (2.9%) and Enterobius vermicularis (0.6%). The mean densities of P. falciparum in children co-infected with S. haematobium and hookworm were higher compared to those infected with P. falciparum only though not statistically significant (p = 0.062). The age distribution of both S. haematobium (p = 0.049) and hookworm (p = 0.034) infected children were statistically significant with the older age group (10–15 years) recording the highest prevalence of 47.2% and 25% respectively

  7. The Density of Knobs on Plasmodium falciparum-Infected Erythrocytes Depends on Developmental Age and Varies among Isolates

    PubMed Central

    Quadt, Katharina A.; Barfod, Lea; Andersen, Daniel; Bruun, Jonas; Gyan, Ben; Hassenkam, Tue; Ofori, Michael F.; Hviid, Lars

    2012-01-01

    Background The virulence of Plasmodium falciparum malaria is related to the parasite’s ability to evade host immunity through clonal antigenic variation and tissue-specific adhesion of infected erythrocytes (IEs). The P. falciparum erythrocyte membrane protein 1 (PfEMP1) family expressed on dome-shaped protrusions called knobs on the IE surface is central to both. Differences in receptor specificity and affinity of expressed PfEMP1 are important for IE adhesiveness, but it is not known whether differences in the number and size of the knobs on which the PfEMP1 proteins are expressed also play a role. Therefore, the aim of this study was to provide detailed information on isolate- and time-dependent differences in knob size and density. Methodology/Principal Findings We used atomic force microscopy to characterize knobs on the surface of P. falciparum-infected erythrocytes. Fourteen ex vivo isolates from Ghanaian children with malaria and 10 P. falciparum isolates selected in vitro for expression of a particular PfEMP1 protein (VAR2CSA) were examined. Knob density increased from ∼20 h to ∼35 h post-invasion, with significant variation among isolates. The knob density ex vivo, which was about five-fold higher than following long-term in vitro culture, started to decline within a few months of culture. Although knob diameter and height varied among isolates, we did not observe significant time-dependent variation in these dimensions. Conclusions/Significance The density of knobs on the P. falciparum-IE surface depends on time since invasion, but is also determined by the infecting isolate in a time-independent manner. This is the first study to quantitatively evaluate knob densities and dimensions on different P. falciparum isolates, to examine ex vivo isolates from humans, and to compare ex vivo and long-term in vitro-cultured isolates. Our findings contribute to the understanding of the interaction between P. falciparum parasites and the infected host. PMID

  8. Plasmodium vivax Sub-Patent Infections after Radical Treatment Are Common in Peruvian Patients: Results of a 1-Year Prospective Cohort Study

    PubMed Central

    Delgado, Christopher; Gamboa, Dionicia; Grande, Tanilu; Rodriguez, Hugo; Llanos-Cuentas, Alejandro; Anné, Jozef; D'Alessandro, Umberto; Erhart, Annette

    2011-01-01

    Background There is an increasing body of literature reporting treatment failure of the currently recommended radical treatment of Plasmodium vivax infections. As P. vivax is the main malaria species outside the African continent, emerging tolerance to its radical treatment regime could have major consequences in countries like Peru, where 80% of malaria cases are due to P. vivax. Here we describe the results of a 1-year longitudinal follow up of 51 confirmed P. vivax patients living around Iquitos, Peruvian Amazon, and treated according to the Peruvian national guidelines. Methodology Each month a blood sample for microscopy and later genotyping was systematically collected. Recent exposure to infection was estimated by detecting antibodies against the P. vivax circumsporozoite protein (CSP) and all PCR confirmed P. vivax infections were genotyped with 16 polymorphic microsatellites. Results During a 1-year period, 84 recurrent infections, 22 positive also by microscopy, were identified, with a median survival time to first recurrent infection of 203 days. Most of them (71%) were asymptomatic; in 13 patients the infection persisted undetected by microscopy for several consecutive months. The genotype of mostly recurrent infections differed from that at day 0 while fewer differences were seen between the recurrent infections. The average expected heterozygosity was 0.56. There was strong linkage disequilibrium (IAs = 0.29, p<1.10−4) that remained also when analyzing only the unique haplotypes, suggesting common inbreeding. Conclusion In Peru, the P. vivax recurrent infections were common and displayed a high turnover of parasite genotypes compared to day 0. Plasmodium vivax patients, even when treated according to the national guidelines, may still represent an important parasite reservoir that can maintain transmission. Any elimination effort should consider such a hidden reservoir. PMID:21297986

  9. Mixed-species associations in cuxiús (genus Chiropotes).

    PubMed

    Shaffer, Christopher A; Barnett, Adrian A; Gregory, Tremaine; de Melo, Fabiano; Moreira, Leandro; Alvim, Thiago H G; Moura, Viviane S; Filó, Anderson; Cardoso, Tatiane; Port-Carvalho, Marcio; Santos, Ricardo Rodrigues dos; Boyle, Sarah A

    2016-05-01

    Polyspecific or mixed-species associations, where two or more species come together to forage and travel as a unit, have been reported in many primate species. These associations appear to offer a number of benefits to the species involved including increased foraging efficiency and decreased risk of predation. While several researchers have suggested that cuxiús (genus Chiropotes) form mixed-species associations, previous studies have not identified the circumstances under which cuxiús form associations or whether they form associations more often than would be expected by chance. Here we present data on the formation of mixed-species associations by four species of cuxiús at eight different sites in Brazil, Suriname, and Guyana. We analyzed data from two of the study sites, (Biological Dynamics of Forest Fragments Project (BDFFP), Brazil and the Upper Essequibo Conservation Concession (UECC), Guyana, to assess whether associations occurred more than would be expected by chance encounters and identify the factors influencing their formation. Cuxiús showed a high degree of inter-site variation in the frequency of time spent in association (ranging from 2 to 26% of observation time) and duration of associations (mean duration from 22 min to 2.5 hr). Sapajus apella was the most common association partner at most sites. At BDFFP, cuxiús formed associations more frequently but not for longer duration than expected by chance. For much of the year at UECC, associations were not more frequent or longer than chance. However, during the dry season, cuxiús formed associations with S. apella significantly more often and for longer duration than predicted by chance. Cuxiús at UECC formed associations significantly more often when in smaller subgroups and when foraging for insects, and alarm called significantly less frequently during associations. We suggest cuxiús form mixed-species associations at some sites as an adaptive strategy to decrease predation risk and

  10. Managing livestock using animal behavior: Mixed-species stocking and flerds

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Mixed-species stocking can foster sound landscape management while offering economic and ecological advantages compared to mono-species stocking. Producers contemplating a mixed-species enterprise should reflect on several considerations before implementing this animal management strategy. Factors...

  11. Surface Area Loss and Increased Sphericity Account for the Splenic Entrapment of Subpopulations of Plasmodium falciparum Ring-Infected Erythrocytes

    PubMed Central

    Safeukui, Innocent; Buffet, Pierre A.; Perrot, Sylvie; Sauvanet, Alain; Aussilhou, Beatrice; Dokmak, Safi; Couvelard, Anne; Hatem, Dominique Cazals; Mohandas, Narla; David, Peter H.; Mercereau-Puijalon, Odile; Milon, Geneviève

    2013-01-01

    Ex vivo perfusion of human spleens revealed innate retention of numerous cultured Plasmodium falciparum ring-infected red blood cells (ring-iRBCs). Ring-iRBC retention was confirmed by a microsphiltration device, a microbead-based technology that mimics the mechanical filtering function of the human spleen. However, the cellular alterations underpinning this retention remain unclear. Here, we use ImageStream technology to analyze infected RBCs’ morphology and cell dimensions before and after fractionation with microsphiltration. Compared to fresh normal RBCs, the mean cell membrane surface area loss of trophozoite-iRBCs, ring-iRBCs and uninfected co-cultured RBCs (uRBCs) was 14.2% (range: 8.3–21.9%), 9.6% (7.3–12.2%) and 3.7% (0–8.4), respectively. Microsphilters retained 100%, ∼50% and 4% of trophozoite-iRBCs, ring-iRBCs and uRBCs, respectively. Retained ring-iRBCs display reduced surface area values (estimated mean, range: 17%, 15–18%), similar to the previously shown threshold of surface-deficient RBCs retention in the human spleen (surface area loss: >18%). By contrast, ring-iRBCs that successfully traversed microsphilters had minimal surface area loss and normal sphericity, suggesting that these parameters are determinants of their retention. To confirm this hypothesis, fresh normal RBCs were exposed to lysophosphatidylcholine to induce a controlled loss of surface area. This resulted in a dose-dependent retention in microsphilters, with complete retention occurring for RBCs displaying >14% surface area loss. Taken together, these data demonstrate that surface area loss and resultant increased sphericity drive ring-iRBC retention in microsphilters, and contribute to splenic entrapment of a subpopulation of ring-iRBCs. These findings trigger more interest in malaria research fields, including modeling of infection kinetics, estimation of parasite load, and analysis of risk factors for severe clinical forms. The determination of the threshold of

  12. Assembly of avian mixed-species flocks in Amazonia.

    PubMed

    Graves, G R; Gotelli, N J

    1993-02-15

    Diamond's "assembly rules" model posits that competitive interactions among species govern the composition of avifaunas. Although originally applied to islands in archipelagoes, this controversial set of hypotheses is difficult to test because islands differ in habitat and resource availability, colonization history, and stochastic effects. Permanent mixed-species flocks of Amazonian birds are a model system for testing the assembly rules hypothesis because flocks occur in relatively homogeneous tracts of rain forest and because resident species are potentially interactive from minute to minute. To analyze cooccurrence patterns of species in flocks, we used null models that incorporate realistic autecological colonization parameters. Potentially competing pairs of congeneric species with similar ecologies cooccur in flocks less often than expected by chance, resulting in perfect checkerboard distributions. Interactions among more distantly related species, however, appear to have little effect on the assembly of mixed-species flocks. Checkerboard distributions enhance local species diversity within habitats by generating different combinations of species in different flocks. This process may have contributed to the immense species richness of the Amazonian avifauna. PMID:8433996

  13. Assembly of avian mixed-species flocks in Amazonia.

    PubMed Central

    Graves, G R; Gotelli, N J

    1993-01-01

    Diamond's "assembly rules" model posits that competitive interactions among species govern the composition of avifaunas. Although originally applied to islands in archipelagoes, this controversial set of hypotheses is difficult to test because islands differ in habitat and resource availability, colonization history, and stochastic effects. Permanent mixed-species flocks of Amazonian birds are a model system for testing the assembly rules hypothesis because flocks occur in relatively homogeneous tracts of rain forest and because resident species are potentially interactive from minute to minute. To analyze cooccurrence patterns of species in flocks, we used null models that incorporate realistic autecological colonization parameters. Potentially competing pairs of congeneric species with similar ecologies cooccur in flocks less often than expected by chance, resulting in perfect checkerboard distributions. Interactions among more distantly related species, however, appear to have little effect on the assembly of mixed-species flocks. Checkerboard distributions enhance local species diversity within habitats by generating different combinations of species in different flocks. This process may have contributed to the immense species richness of the Amazonian avifauna. PMID:8433996

  14. Chemokines responses to Plasmodium falciparum malaria and co-infections among rural Cameroonians.

    PubMed

    Che, Jane Nchangnwi; Nmorsi, Onyebiguwa Patrick Goddey; Nkot, Baleguel Pierre; Isaac, Clement; Okonkwo, Browne Chukwudi

    2015-04-01

    Malaria remains the major cause of disease morbidity and mortality in sub-Saharan Africa with complex immune responses associated with disease outcomes. Symptoms associated with severe malaria have generally shown chemokine upregulation but little is known of responses to uncomplicated malaria. Eight villages in central Cameroon of 1045 volunteers were screened. Among these, malaria-positive individuals with some healthy controls were selected for chemokine analysis using Enzyme-Linked Immunosorbent Assay (ELISA) kits. Depressed serum levels of CXCL5 and raised CCL28 were observed in malarial positives when compared with healthy controls. The mean concentration of CXCL11 was higher in symptomatic than asymptomatic group, while CCL28 was lower in symptomatic individuals. Lower chemokine levels were associated with symptoms of uncomplicated malaria except for CXCL11 which was upregulated among fever-positive group. The mean CXCL5 level was higher in malaria sole infection than co-infections with HIV and Loa loa. Also, there was a raised mean level of malaria+HIV co-infection for CXCL9. This study hypothesises a situation where depressed chemokines in the face of clinical presentations could indicate an attempt by the immune system in preventing a progression process from uncomplicated to complicated outcomes with CXCL11 being identified as possible biomarker for malarial fever. PMID:25462711

  15. Cytokine dysregulation associated with malarial anemia in Plasmodium yoelii infected mice

    PubMed Central

    Xu, Lili; Zheng, Xiaoying; Berzins, Klavs; Chaudhuri, Asok

    2013-01-01

    The mechanisms of malaria anemia remain incompletely understood although much effort has been put on studies in both human and murine systems. Hematopoiesis is regulated by the proliferation, differentiation and maturation of erythropoietic progenitor cells into erythrocytes and is tightly controlled by a complex communication network of cytokines as signal mediators. The present study used the murine P. yoelii 17XNL malaria model to investigate the profile of cytokines and leukocytes throughout the entire infection. Moreover, malaria induced anemia was studied in comparison with anemia induced by hemorrhage and hemolysis. During the P. yoelii infection, the levels of erythropoietic-related cytokines, such as G-CSF, GMCSF, IL-7, and IL-17, were pronouncedly reduced, while those of regulatory cytokines, such as IL-10 and TNF-α, were constantly increased. This cytokine profile corresponded well with the cellular composition during the infection, such as drastically decreased levels of CD4+ and CD8+ T cells. The profiles of erythropoiesis or hematopoiesis related cytokines during malarial anemia showed striking differences from those during anemia induced by hemorrhage or hemolysis. This study demonstrates that a markedly dysregulated cytokine network occurred in this murine malaria model, which may open a new window of insight into the mechanisms of malaria related anemia. PMID:23573367

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

    PubMed Central

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

    2015-01-01

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

  17. 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

  18. Efficacy of OZ439 (artefenomel) against early Plasmodium falciparum blood-stage malaria infection in healthy volunteers

    PubMed Central

    McCarthy, James S.; Baker, Mark; O'Rourke, Peter; Marquart, Louise; Griffin, Paul; Hooft van Huijsduijnen, Rob; Möhrle, Jörg J.

    2016-01-01

    Objectives OZ439, or artefenomel, is an investigational synthetic ozonide antimalarial with similar potency, but a significantly improved pharmacokinetic profile, compared with artemisinins. We wished to measure key pharmacokinetic and pharmacodynamic parameters and the pharmacokinetic/pharmacodynamic relationship of artefenomel in humans to guide the drug's further development as combination therapy in patients. Patients and methods We tested artefenomel in the human induced blood-stage malaria (IBSM) model. Plasmodium infection was monitored by quantitative PCR (qPCR) and upon reaching 1000 parasites/mL single doses of 100, 200 and 500 mg of artefenomel were administered orally with evaluation of drug exposure and parasitaemia until rescue treatment after 16 days or earlier, if required. Results A single 100 mg dose had only a transient effect, while the 200 mg dose resulted in a significant reduction in parasitaemia before early recrudescence. At the highest (500 mg) dose, initial clearance of parasites below the limit of detection of qPCR was observed, with a 48 h parasite reduction ratio (PRR48) >10 000 and a parasite clearance half-life of 3.6 h (95% CI 3.4–3.8 h). However, at this dose, recrudescence was seen in four of eight subjects 6–10 days after treatment. Pharmacokinetic/pharmacodynamic modelling predicted an MIC of 4.1 ng/mL. Conclusions These results confirm the antimalarial potential of artefenomel for use in a single-exposure combination therapy. The observations from this study support and will assist further clinical development of artefenomel. PMID:27272721

  19. 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

  20. Immunoliposome-mediated drug delivery to Plasmodium-infected and non-infected red blood cells as a dual therapeutic/prophylactic antimalarial strategy.

    PubMed

    Moles, Ernest; Urbán, Patricia; Jiménez-Díaz, María Belén; Viera-Morilla, Sara; Angulo-Barturen, Iñigo; Busquets, Maria Antònia; Fernàndez-Busquets, Xavier

    2015-07-28

    One of the most important factors behind resistance evolution in malaria is the failure to deliver sufficiently high amounts of drugs to early stages of Plasmodium-infected red blood cells (pRBCs). Despite having been considered for decades as a promising approach, the delivery of antimalarials encapsulated in immunoliposomes targeted to pRBCs has not progressed towards clinical applications, whereas in vitro assays rarely reach drug efficacy improvements above 10-fold. Here we show that encapsulation efficiencies reaching >96% are achieved for the weak basic drugs chloroquine (CQ) and primaquine using the pH gradient loading method in liposomes containing neutral saturated phospholipids. Targeting antibodies are best conjugated through their primary amino groups, adjusting chemical crosslinker concentration to retain significant antigen recognition. Antigens from non-parasitized RBCs have also been considered as targets for the delivery to the cell of drugs not affecting the erythrocytic metabolism. Using this strategy, we have achieved unprecedented complete nanocarrier targeting to early intraerythrocytic stages of the malaria parasite for which there is a lack of specific extracellular molecular tags. Immunoliposomes studded with monoclonal antibodies raised against the erythrocyte surface protein glycophorin A were capable of targeting 100% RBCs and pRBCs at the low concentration of 0.5μM total lipid in the culture, with >95% of added liposomes retained on cell surfaces. When exposed for only 15min to Plasmodium falciparum in vitro cultures of early stages, free CQ had no significant effect on the viability of the parasite up to 200nM, whereas immunoliposomal 50nM CQ completely arrested its growth. In vivo assays in mice showed that immunoliposomes cleared the pathogen below detectable levels at a CQ dose of 0.5mg/kg, whereas free CQ administered at 1.75mg/kg was, at most, 40-fold less efficient. Our data suggest that this significant improvement is in part

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

    PubMed Central

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

    2010-01-01

    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 twenty standard deviations larger than uninfected erythrocytes, which suggests that relatively low infection levels can be studied with this technique. PMID:21043509

  2. 2-Hexadecynoic Acid Inhibits Plasmodial FAS-II Enzymes and Arrest Erythrocytic and Liver Stage Plasmodium Infections

    PubMed Central

    Tasdemir, Deniz; Sanabria, David; Lauinger, Ina L.; Tarun, Alice; Herman, Rob; Perozzo, Remo; Zloh, Mire; Kappe, Stefan H.; Brun, Reto; Carballeira, Néstor M.

    2010-01-01

    Acetylenic fatty acids are known to display several biological activities, but their antimalarial activity has remained unexplored. In this study, we synthesized the 2-, 5-, 6-, and 9-hexadecynoic acids (HDAs) and evaluated their in vitro activity against erythrocytic (blood) stages of Plasmodium falciparum and liver stages of P. yoelii infections. Since the type II fatty acid biosynthesis pathway (PfFAS-II) has recently been shown to be indispensable for liver stage malaria parasites, the inhibitory potential of the HDAs against multiple P. falciparum FAS-II (PfFAS-II) elongation enzymes was also evaluated. The highest antiplasmodial activity against blood stages of P. falciparum was displayed by 5-HDA (IC50 value 6.6. μg/ml), whereas the 2-HDA was the only acid arresting the growth of liver stage P. yoelii infection, in both flow cytometric assay (IC50 value 2-HDA 15.3 μg/ml, control drug atovaquone 2.5 ng/ml) and immunofluorescense analysis (IC50 2-HDA 4.88 μg/ml, control drug atovaquone 0.37 ng/ml). 2-HDA showed the best inhibitory against the PfFAS-II enzymes PfFabI and PfFabZ with IC50 values of 0.38 and 0.58 μg/ml (IC50 control drugs 14 and 30 ng/ml) respectively. Enzyme kinetics and molecular modeling studies revealed valuable insights into the binding mechanism of 2-HDA on the target enzymes. All HDAs showed in vitro activity against Trypanosoma brucei rhodesiense (IC50 values 3.7–31.7 μg/ml), Trypanosoma cruzi (only 2-HDA, IC50 20.2 μg/ml), and Leishmania donovani (IC50 values 4.1–13.4 μg/ml) with generally low or no significant toxicity on mammalian cells. This is the first study to indicate therapeutic potential of HDAs against various parasitic protozoa. It also points out that the malarial liver stage growth inhibitory effect of the 2-HDA may be promoted via PfFAS-II enzymes. The lack of cytotoxicity, lipophilic nature and calculated pharmacokinetic properties suggest that 2-HDA could be a useful compound to study the interaction of fatty

  3. Review: HIV-Plasmodium Co-infection: Malaria in AIDS patients.

    PubMed

    Qadir, Muhammad Imran; Maqbool, Faheem; Maqbool, Ayesha; Ali, Muhammad

    2015-09-01

    Malaria and HIV are amongst the two main diseases worldwide and creating troubles of our time. Together, they grounds extra than four million deaths a year. Malaria causes around about for more than a million deaths each year, of which over 80-90 % come about in tropical Africa, somewhere malaria is the primary source of mortality in children below six years of age. Sideways as of adolescent, children, pregnant women are surrounded by the largest part exaggerated by the disease. In the wide geographical extend beyond in event and the follow-on co-infection, the interface flanked as a result of the two diseases visibly has foremost communal strength results. Thus both are dangerous for health at the same time. PMID:26408902

  4. Hand specialization, sympatry, and mixed-species associations in callitrichines.

    PubMed

    César, J; Bicca-Marques, J C

    1999-04-01

    Hand morphology in callitrichines (i.e., tamarins, marmosets, and Goeldi's monkey) is correlated with positional and foraging behaviors. This study examines hand shape in callitrichines using an allometric approach. It addresses a series of questions relating hand anatomy, insect foraging behavior, and resource partitioning in callitrichines. The main questions are: 1. Do the hands of Leontopithecus differ in shape from all other callitrichine taxa allowing it to perform highly manipulative prey foraging behaviors? 2. Are the hands of Saguinus fuscicollis adapted to manipulative foraging, and are they functionally similar to Leontopithecus' hands? 3. Is hand morphology in S. fuscicollis more similar to the hand morphology of sympatric tamarin species with whom it does not form mixed species troops (S. nigricollis and S. tripartitus) than to those sympatric tamarin species with whom it does form mixed troops (S. mystax, S. labiatus, and S. imperator)? Measurements of hand length (HL), width (HW), and thickness (HT) were taken from 1350 museum specimens of callitrichines (Callithrix, Cebuella, Leontopithecus, Saguinus, and Callimico), squirrel monkeys (Saimiri), and owl monkeys (Aotus). The analysis indicates that hand shape covaries with foraging strategy. Specifically, the hands of Leontopithecus are adapted for manipulative foraging and are relatively longer and more slender than the hands of other callitrichines. A similar pattern is observed in the hands of S. fuscicollis, S. tripartitus and S. nigricollis. These latter species, however, differ significantly in shape from all other tamarin species. Large differences in hand morphology are observed among tamarin species that form mixed-species troops. These anatomical differences may permit resource partitioning and coexistence among these closely related taxa. Hand shape, expressed as log HLGM (logged hand length divided by the geometric mean of all measurements), is a good predictor of manipulative and non

  5. Vitamin A supplements, routine immunization, and the subsequent risk of Plasmodium infection among children under 5 years in sub-Saharan Africa

    PubMed Central

    Hollm-Delgado, Maria-Graciela; Piel, Frédéric B; Weiss, Daniel J; Howes, Rosalind E; Stuart, Elizabeth A; Hay, Simon I; Black, Robert E

    2015-01-01

    Recent studies, partly based on murine models, suggest childhood immunization and vitamin A supplements may confer protection against malaria infection, although strong evidence to support these theories in humans has so far been lacking. We analyzed national survey data from children aged 6–59 months in four sub-Saharan African countries over an 18-month time period, to determine the risk of Plasmodium spp. parasitemia (n=8390) and Plasmodium falciparum HRP-2 (PfHRP-2)-related antigenemia (n=6121) following vitamin A supplementation and standard vaccination. Bacille Calmette Guerin-vaccinated children were more likely to be PfHRP-2 positive (relative risk [RR]=4.06, 95% confidence interval [CI]=2.00–8.28). No association was identified with parasitemia. Measles and polio vaccination were not associated with malaria. Children receiving vitamin A were less likely to present with parasitemia (RR=0.46, 95% CI=0.39–0.54) and antigenemia (RR=0.23, 95% CI=0.17–0.29). Future studies focusing on climate seasonality, placental malaria and HIV are needed to characterize better the association between vitamin A and malaria infection in different settings. DOI: http://dx.doi.org/10.7554/eLife.03925.001 PMID:25647726

  6. Vitamin A supplements, routine immunization, and the subsequent risk of Plasmodium infection among children under 5 years in sub-Saharan Africa.

    PubMed

    Hollm-Delgado, Maria-Graciela; Piel, Frédéric B; Weiss, Daniel J; Howes, Rosalind E; Stuart, Elizabeth A; Hay, Simon I; Black, Robert E

    2014-01-01

    Recent studies, partly based on murine models, suggest childhood immunization and vitamin A supplements may confer protection against malaria infection, although strong evidence to support these theories in humans has so far been lacking. We analyzed national survey data from children aged 6-59 months in four sub-Saharan African countries over an 18-month time period, to determine the risk of Plasmodium spp. parasitemia (n=8390) and Plasmodium falciparum HRP-2 (PfHRP-2)-related antigenemia (n=6121) following vitamin A supplementation and standard vaccination. Bacille Calmette Guerin-vaccinated children were more likely to be PfHRP-2 positive (relative risk [RR]=4.06, 95% confidence interval [CI]=2.00-8.28). No association was identified with parasitemia. Measles and polio vaccination were not associated with malaria. Children receiving vitamin A were less likely to present with parasitemia (RR=0.46, 95% CI=0.39-0.54) and antigenemia (RR=0.23, 95% CI=0.17-0.29). Future studies focusing on climate seasonality, placental malaria and HIV are needed to characterize better the association between vitamin A and malaria infection in different settings. PMID:25647726

  7. Evolution of GOUNDRY, a cryptic subgroup of Anopheles gambiae s.l., and its impact on susceptibility to Plasmodium infection.

    PubMed

    Crawford, Jacob E; Riehle, Michelle M; Markianos, Kyriacos; Bischoff, Emmanuel; Guelbeogo, Wamdaogo M; Gneme, Awa; Sagnon, N'Fale; Vernick, Kenneth D; Nielsen, Rasmus; Lazzaro, Brian P

    2016-04-01

    The recent discovery of a previously unknown genetic subgroup of Anopheles gambiae sensu lato underscores our incomplete understanding of complexities of vector population demographics in Anopheles. This subgroup, named GOUNDRY, does not rest indoors as adults and is highly susceptible to Plasmodium infection in the laboratory. Initial description of GOUNDRY suggested it differed from other known Anopheles taxa in surprising and sometimes contradictory ways, raising a number of questions about its age, population size and relationship to known subgroups. To address these questions, we sequenced the complete genomes of 12 wild-caught GOUNDRY specimens and compared these genomes to a panel of Anopheles genomes. We show that GOUNDRY is most closely related to Anopheles coluzzii, and the timing of cladogenesis is not recent, substantially predating the advent of agriculture. We find a large region of the X chromosome that has swept to fixation in GOUNDRY within the last 100 years, which may be an inversion that serves as a partial barrier to contemporary gene flow. Interestingly, we show that GOUNDRY has a history of inbreeding that is significantly associated with susceptibility to Plasmodium infection in the laboratory. Our results illuminate the genomic evolution of one of probably several cryptic, ecologically specialized subgroups of Anopheles and provide a potent example of how vector population dynamics may complicate efforts to control or eradicate malaria. PMID:26846876

  8. Growth and Detachment of Cell Clusters from Mature Mixed-Species Biofilms

    PubMed Central

    Stoodley, Paul; Wilson, Suzanne; Hall-Stoodley, Luanne; Boyle, John D.; Lappin-Scott, Hilary M.; Costerton, J. W.

    2001-01-01

    Detachment from biofilms is an important consideration in the dissemination of infection and the contamination of industrial systems but is the least-studied biofilm process. By using digital time-lapse microscopy and biofilm flow cells, we visualized localized growth and detachment of discrete cell clusters in mature mixed-species biofilms growing under steady conditions in turbulent flow in situ. The detaching biomass ranged from single cells to an aggregate with a diameter of approximately 500 μm. Direct evidence of local cell cluster detachment from the biofilms was supported by microscopic examination of filtered effluent. Single cells and small clusters detached more frequently, but larger aggregates contained a disproportionately high fraction of total detached biomass. These results have significance in the establishment of an infectious dose and public health risk assessment. PMID:11722913

  9. Differences in susceptibility among mouse strains to infection with Plasmodium berghei (ANKA clone) sporozoites and its relationship to protection by gamma-irradiated sporozoites

    SciTech Connect

    Jaffe, R.I.; Lowell, G.H.; Gordon, D.M. )

    1990-04-01

    Three inbred mouse strains, C57BL/6 (H-2b), A/J (H-2a), and BALB/c (H-2d), and 1 outbred strain, CD-1, demonstrated differences in susceptibility to iv challenge with the ANKA clone of Plasmodium berghei. Mice were challenged with 100, 1,000, or 10,000 sporozoites, then evaluated daily beginning on day 4 for patency. CD-1 mice were further evaluated at challenge doses of 12,500, 25,000, and 50,000 sporozoites. C57BL/6 mice were the easiest to infect, with 90% becoming infected with 100 sporozoites. The outbred strain CD-1 was the most difficult to infect, requiring a challenge dose of 25,000 sporozoites/mouse in order to achieve a 100% infection rate. Mouse strains also demonstrated differences in their ability to be protected by intravenous immunization with gamma-irradiated sporozoites. A/J mice needed a minimum of 3 doses of irradiated sporozoites for protection against a challenge with 10,000 sporozoites. In contrast, BALB/c mice immunized with a single dose of 1,000 irradiated sporozoites are protected against a 10,000 sporozoite challenge. These data suggest that both infectivity and protection are genetically restricted and that susceptibility to infection may be inversely related to protection.

  10. Differences in susceptibility among mouse strains to infection with Plasmodium berghei (ANKA clone) sporozoites and its relationship to protection by gamma-irradiated sporozoites

    SciTech Connect

    Jaffe, R.I.; Lowell, G.H.; Gordon, D.M.

    1990-01-01

    Three inbred mouse strains, C57BL/6 (H-2/b/), A/J (H-2/a/), and BALB/C (H-2/d/), and one outbred strain, CD-1, demonstrated differences in susceptibility to challenge intravenously with the ANKA clone of Plasmodium berghei. Mice were challenged with 100, 1000, or 10000 sporozoites, then evaluated daily beginning on day 4 for patency. CD-1 mice were further evaluated at challenge doses of 125000, 25000, and 50000 sporozoites. C57BL/6 mice were the easiest to infect with 90% becoming infected with 100 sporozoites. The outbred strain CD-1 was the most difficult to infect requiring a challenge dose of 25000 sporozoites per mouse in order to achieve a 100% infection rate. Mouse strains also demonstrated differences in their ability to be protected by intravenous immunization with gamma-irradiated sporozoites. A/J mice needed a minimum of 3 doses of irradiated sporozoites for protection against a challenge with 1000 sporozoites. In contrast BALB/C mice, immunized with a single dose of 1000 irradiated sporozoites, are protected against a 10000 sporozoite challenge. These data suggest that both infectivity and protection are genetically restricted and that susceptibility to infection may be inversely related to protection.

  11. Millimeter scale electron conduction through exoelectrogenic mixed species biofilms.

    PubMed

    Li, Cheng; Lesnik, Keaton Larson; Fan, Yanzhen; Liu, Hong

    2016-08-01

    The functioning of many natural and engineered environments is dependent on long distance electron transfer mediated through electrical currents. These currents have been observed in exoelectrogenic biofilms and it has been proposed that microbial biofilms can mediate electron transfer via electrical currents on the centimeter scale. However, direct evidence to confirm this hypothesis has not been demonstrated and the longest known electrical transfer distance for single species exoelectrogenic biofilms is limited to 100 μm. In the present study, biofilms were developed on electrodes with electrically non-conductive gaps from 50 μm to 1 mm and the in situ conductance of biofilms was evaluated over time. Results demonstrated that the exoelectrogenic mixed species biofilms in the present study possess the ability to transfer electrons through electrical currents over a distance of up to 1 mm, 10 times further than previously observed. Results indicate the possibility of interspecies interactions playing an important role in the spatial development of exoelectrogenic biofilms, suggesting that these biological networks might remain conductive even at longer distance. These findings have significant implications in regards to future optimization of microbial electrochemical systems. PMID:27279626

  12. Mixed Species Ion Chains for Scalable Quantum Computation

    NASA Astrophysics Data System (ADS)

    Wright, John Albert

    Mixed species chains of barium and ytterbium ions are investigated as a tool for building scalable quantum computation devices. Ytterbium ions provide a stable, environmentally-insensitive qubit that is easily initialized and manipulated, while barium ions are easily entangled with photons that can allow quantum information to be transmitted between systems in modular quantum computation units. Barium and ytterbium are trapped together in a linear chain in a linear rf trap and their normal mode structure and the thermal occupation numbers of these modes are measured with a narrow band laser addressing an electric quadrupole transition in barium ions. Before these measurements, barium ions are directly cooled using Doppler cooling, while the ytterbium ions are sympathetically cooled by the barium. For radial modes strongly coupled to ytterbium ions the average thermal occupation numbers vary between 400 and 12,000 depending on ion species configuration and trap parameters. Ion chain temperatures are also measured using a technique based on ion species reordering. Surface traps with many dc electrodes provide the ability to controllably reorder the chain to optimize normal mode cooling, and initial work towards realizing this capability are discussed. Quantum information can be transferred between ions in a linear chain using an optical system that is well coupled to the motional degrees of freedom of the chain. For this reason, a 532 nm Raman system is developed and its expected performance is evaluated.

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

    PubMed

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

    2016-05-01

    Plasmodium falciparum erythrocyte membrane protein 1 (PfEMP1), expressed on P. falciparum-infected erythrocytes, is a major family of clonally variant targets of naturally acquired immunity to malaria. Previous studies have demonstrated that in areas where malaria is endemic, antibodies to infected erythrocytes from children with severe malaria tend to be more seroprevalent than antibodies to infected erythrocytes from children with nonsevere malaria. These data have led to a working hypothesis that PfEMP1 variants associated with parasite virulence are relatively conserved in structure. However, the longevity of such serologically conserved variants in the parasite population is unknown. Here, using infected erythrocytes from recently sampled clinical P. falciparum samples, we measured serological conservation using pools of antibodies in sera that had been sampled 10 to 12 years earlier. The serological conservation of infected erythrocytes strongly correlated with the expression of specific PfEMP1 subsets previously found to be associated with severe malaria. However, we found no association between serological conservation per se and disease severity within these data. This contrasts with the simple hypothesis that P. falciparum isolates with a serologically conserved group of PfEMP1 variants cause severe malaria. The data are instead consistent with periodic turnover of the immunodominant epitopes of PfEMP1 associated with severe malaria. PMID:26883585

  14. The Costimulatory Molecule ICOS Regulates Host Th1 and Follicular Th Cell Differentiation in Response to Plasmodium chabaudi chabaudi AS Infection.

    PubMed

    Wikenheiser, Daniel J; Ghosh, Debopam; Kennedy, Brian; Stumhofer, Jason S

    2016-01-15

    Blood-stage Plasmodium chabaudi chabaudi AS infection requires cell- and Ab-mediated immunity to control acute and persistent infection, respectively. ICOS regulates CD4(+) T cell activation and promotes the induction of follicular Th (TFH) cells, CD4(+) T cells that support B cell affinity maturation within germinal centers (GCs), resulting in the production of high-affinity Abs. In this article, we demonstrate that, in response to P. c. chabaudi AS infection, the absence of ICOS resulted in an enhanced Th1 immune response that reduced peak parasitemia. Despite the absence of ICOS, CD4(+) T cells were capable of expressing PD-1, B cell lymphoma 6, and CXCR5 during early infection, indicating TFH development was not impaired. However, by day 21 postinfection, Icos(-/-) mice accumulated fewer splenic TFHs compared with Icos(+/+) mice, leading to substantially fewer GC B cells and a decrease in affinity, but not production, of parasite-specific isotype-switched Abs. Moreover, treatment of mice with anti-ICOS ligand Abs to modulate ICOS-ICOS ligand signaling revealed a requirement for ICOS in TFH differentiation only after day 6 postinfection. Ultimately, the quality and quantity of isotype-switched Abs produced in Icos(-/-) mice declined over time, resulting in impaired control of persistent parasitemia. Collectively, these data suggest ICOS is not required for TFH induction during P. c. chabaudi AS infection or production of isotype-switched Abs, but it is necessary for maintenance of a sustained high-affinity, protective Ab response. PMID:26667167

  15. Plasmodium yoelii infection of BALB/c mice results in expansion rather than induction of CD4(+) Foxp3(+) regulatory T cells.

    PubMed

    Abel, Simone; Ueffing, Kristina; Tatura, Roman; Hutzler, Marina; Hose, Matthias; Matuschewski, Kai; Kehrmann, Jan; Westendorf, Astrid M; Buer, Jan; Hansen, Wiebke

    2016-06-01

    Recently, we demonstrated elevated numbers of CD4(+) Foxp3(+) regulatory T (Treg) cells in Plasmodium yoelii-infected mice contributing to the regulation of anti-malarial immune response. However, it remains unclear whether this increase in Treg cells is due to thymus-derived Treg cell expansion or induction of Treg cells in the periphery. Here, we show that the frequency of Foxp3(+) Treg cells expressing neuropilin-1 (Nrp-1) decreased at early time-points during P. yoelii infection, whereas percentages of Helios(+) Foxp3(+) Treg cells remained unchanged. Both Foxp3(+) Nrp-1(+) and Foxp3(+) Nrp-1(-) Treg cells from P. yoelii-infected mice exhibited a similar T-cell receptor Vβ chain usage and methylation pattern in the Treg-specific demethylation region within the foxp3 locus. Strikingly, we did not observe induction of Foxp3 expression in Foxp3(-) T cells adoptively transferred to P. yoelii-infected mice. Hence, our results suggest that P. yoelii infection triggered expansion of naturally occurring Treg cells rather than de novo induction of Foxp3(+) Treg cells. PMID:26932746

  16. Stearylamine Liposomal Delivery of Monensin in Combination with Free Artemisinin Eliminates Blood Stages of Plasmodium falciparum in Culture and P. berghei Infection in Murine Malaria

    PubMed Central

    Rohra, Shilpa; Raza, Mohsin; Hasan, Gulam Mustafa; Dutt, Suparna

    2015-01-01

    The global emergence of drug resistance in malaria is impeding the therapeutic efficacy of existing antimalarial drugs. Therefore, there is a critical need to develop an efficient drug delivery system to circumvent drug resistance. The anticoccidial drug monensin, a carboxylic ionophore, has been shown to have antimalarial properties. Here, we developed a liposome-based drug delivery of monensin and evaluated its antimalarial activity in lipid formulations of soya phosphatidylcholine (SPC) cholesterol (Chol) containing either stearylamine (SA) or phosphatidic acid (PA) and different densities of distearoyl phosphatidylethanolamine-methoxy-polyethylene glycol 2000 (DSPE-mPEG-2000). These formulations were found to be more effective than a comparable dose of free monensin in Plasmodium falciparum (3D7) cultures and established mice models of Plasmodium berghei strains NK65 and ANKA. Parasite killing was determined by a radiolabeled [3H]hypoxanthine incorporation assay (in vitro) and microscopic counting of Giemsa-stained infected erythrocytes (in vivo). The enhancement of antimalarial activity was dependent on the liposomal lipid composition and preferential uptake by infected red blood cells (RBCs). The antiplasmodial activity of monensin in SA liposome (50% inhibitory concentration [IC50], 0.74 nM) and SPC:Chol-liposome with 5 mol% DSPE-mPEG 2000 (IC50, 0.39 nM) was superior to that of free monensin (IC50, 3.17 nM), without causing hemolysis of erythrocytes. Liposomes exhibited a spherical shape, with sizes ranging from 90 to 120 nm, as measured by dynamic light scattering and high-resolution electron microscopy. Monensin in long-circulating liposomes of stearylamine with 5 mol% DSPE-mPEG 2000 in combination with free artemisinin resulted in enhanced killing of parasites, prevented parasite recrudescence, and improved survival. This is the first report to demonstrate that monensin in PEGylated stearylamine (SA) liposome has therapeutic potential against malaria

  17. Stearylamine Liposomal Delivery of Monensin in Combination with Free Artemisinin Eliminates Blood Stages of Plasmodium falciparum in Culture and P. berghei Infection in Murine Malaria.

    PubMed

    Rajendran, Vinoth; Rohra, Shilpa; Raza, Mohsin; Hasan, Gulam Mustafa; Dutt, Suparna; Ghosh, Prahlad C

    2016-03-01

    The global emergence of drug resistance in malaria is impeding the therapeutic efficacy of existing antimalarial drugs. Therefore, there is a critical need to develop an efficient drug delivery system to circumvent drug resistance. The anticoccidial drug monensin, a carboxylic ionophore, has been shown to have antimalarial properties. Here, we developed a liposome-based drug delivery of monensin and evaluated its antimalarial activity in lipid formulations of soya phosphatidylcholine (SPC) cholesterol (Chol) containing either stearylamine (SA) or phosphatidic acid (PA) and different densities of distearoyl phosphatidylethanolamine-methoxy-polyethylene glycol 2000 (DSPE-mPEG-2000). These formulations were found to be more effective than a comparable dose of free monensin in Plasmodium falciparum (3D7) cultures and established mice models of Plasmodium berghei strains NK65 and ANKA. Parasite killing was determined by a radiolabeled [(3)H]hypoxanthine incorporation assay (in vitro) and microscopic counting of Giemsa-stained infected erythrocytes (in vivo). The enhancement of antimalarial activity was dependent on the liposomal lipid composition and preferential uptake by infected red blood cells (RBCs). The antiplasmodial activity of monensin in SA liposome (50% inhibitory concentration [IC50], 0.74 nM) and SPC:Chol-liposome with 5 mol% DSPE-mPEG 2000 (IC50, 0.39 nM) was superior to that of free monensin (IC50, 3.17 nM), without causing hemolysis of erythrocytes. Liposomes exhibited a spherical shape, with sizes ranging from 90 to 120 nm, as measured by dynamic light scattering and high-resolution electron microscopy. Monensin in long-circulating liposomes of stearylamine with 5 mol% DSPE-mPEG 2000 in combination with free artemisinin resulted in enhanced killing of parasites, prevented parasite recrudescence, and improved survival. This is the first report to demonstrate that monensin in PEGylated stearylamine (SA) liposome has therapeutic potential against malaria

  18. Antibody Responses to a Novel Plasmodium falciparum Merozoite Surface Protein Vaccine Correlate with Protection against Experimental Malaria Infection in Aotus Monkeys

    PubMed Central

    Cavanagh, David R.; Kocken, Clemens H. M.; White, John H.; Cowan, Graeme J. M.; Samuel, Kay; Dubbeld, Martin A.; der Wel, Annemarie Voorberg-van; Thomas, Alan W.; McBride, Jana S.; Arnot, David E.

    2014-01-01

    The Block 2 region of the merozoite surface protein-1 (MSP-1) of Plasmodium falciparum has been identified as a target of protective immunity by a combination of seroepidemiology and parasite population genetics. Immunogenicity studies in small animals and Aotus monkeys were used to determine the efficacy of recombinant antigens derived from this region of MSP-1 as a potential vaccine antigen. Aotus lemurinus griseimembra monkeys were immunized three times with a recombinant antigen derived from the Block 2 region of MSP-1 of the monkey-adapted challenge strain, FVO of Plasmodium falciparum, using an adjuvant suitable for use in humans. Immunofluorescent antibody assays (IFA) against erythrocytes infected with P. falciparum using sera from the immunized monkeys showed that the MSP-1 Block 2 antigen induced significant antibody responses to whole malaria parasites. MSP-1 Block 2 antigen-specific enzyme-linked immunosorbent assays (ELISA) showed no significant differences in antibody titers between immunized animals. Immunized animals were challenged with the virulent P. falciparum FVO isolate and monitored for 21 days. Two out of four immunized animals were able to control their parasitaemia during the follow-up period, whereas two out of two controls developed fulminating parasitemia. Parasite-specific serum antibody titers measured by IFA were four-fold higher in protected animals than in unprotected animals. In addition, peptide-based epitope mapping of serum antibodies from immunized Aotus showed distinct differences in epitope specificities between protected and unprotected animals. PMID:24421900

  19. Antibody responses to a novel Plasmodium falciparum merozoite surface protein vaccine correlate with protection against experimental malaria infection in Aotus monkeys.

    PubMed

    Cavanagh, David R; Kocken, Clemens H M; White, John H; Cowan, Graeme J M; Samuel, Kay; Dubbeld, Martin A; Voorberg-van der Wel, Annemarie; Thomas, Alan W; McBride, Jana S; Arnot, David E

    2014-01-01

    The Block 2 region of the merozoite surface protein-1 (MSP-1) of Plasmodium falciparum has been identified as a target of protective immunity by a combination of seroepidemiology and parasite population genetics. Immunogenicity studies in small animals and Aotus monkeys were used to determine the efficacy of recombinant antigens derived from this region of MSP-1 as a potential vaccine antigen. Aotus lemurinus griseimembra monkeys were immunized three times with a recombinant antigen derived from the Block 2 region of MSP-1 of the monkey-adapted challenge strain, FVO of Plasmodium falciparum, using an adjuvant suitable for use in humans. Immunofluorescent antibody assays (IFA) against erythrocytes infected with P. falciparum using sera from the immunized monkeys showed that the MSP-1 Block 2 antigen induced significant antibody responses to whole malaria parasites. MSP-1 Block 2 antigen-specific enzyme-linked immunosorbent assays (ELISA) showed no significant differences in antibody titers between immunized animals. Immunized animals were challenged with the virulent P. falciparum FVO isolate and monitored for 21 days. Two out of four immunized animals were able to control their parasitaemia during the follow-up period, whereas two out of two controls developed fulminating parasitemia. Parasite-specific serum antibody titers measured by IFA were four-fold higher in protected animals than in unprotected animals. In addition, peptide-based epitope mapping of serum antibodies from immunized Aotus showed distinct differences in epitope specificities between protected and unprotected animals. PMID:24421900

  20. The Incidence and Differential Seasonal Patterns of Plasmodium vivax Primary Infections and Relapses in a Cohort of Children in Papua New Guinea.

    PubMed

    Ross, Amanda; Koepfli, Cristian; Schoepflin, Sonja; Timinao, Lincoln; Siba, Peter; Smith, Thomas; Mueller, Ivo; Felger, Ingrid; Tanner, Marcel

    2016-05-01

    Plasmodium vivax has the ability to relapse from dormant parasites in the liver weeks or months after inoculation, causing further blood-stage infection and potential onward transmission. Estimates of the force of blood-stage infections arising from primary infections and relapses are important for designing intervention strategies. However, in endemic settings their relative contributions are unclear. Infections are frequently asymptomatic, many individuals harbor multiple infections, and while high-resolution genotyping of blood samples enables individual infections to be distinguished, primary infections and relapses cannot be identified. We develop a model and fit it to longitudinal genotyping data from children in Papua New Guinea to estimate the incidence and seasonality of P vivax primary infection and relapse. The children, aged one to three years at enrolment, were followed up over 16 months with routine surveys every two months. Blood samples were taken at the routine visits and at other times if the child was ill. Samples positive by microscopy or a molecular method for species detection were genotyped using high-resolution capillary electrophoresis for P vivax MS16 and msp1F3, and P falciparum msp2. The data were summarized as longitudinal patterns of success or failure to detect a genotype at each routine time-point (eg 001000001). We assume that the seasonality of P vivax primary infection is similar to that of P falciparum since they are transmitted by the same vectors and, because P falciparum does not have the ability to relapse, the seasonality can be estimated. Relapses occurring during the study period can be a consequence of infections occurring prior to the study: we assume that the seasonal pattern of primary infections repeats over time. We incorporate information from parasitological and entomology studies to gain leverage for estimating the parameters, and take imperfect detection into account. We estimate the force of P vivax primary

  1. The Incidence and Differential Seasonal Patterns of Plasmodium vivax Primary Infections and Relapses in a Cohort of Children in Papua New Guinea

    PubMed Central

    Ross, Amanda; Koepfli, Cristian; Schoepflin, Sonja; Timinao, Lincoln; Siba, Peter; Smith, Thomas; Mueller, Ivo; Felger, Ingrid; Tanner, Marcel

    2016-01-01

    Plasmodium vivax has the ability to relapse from dormant parasites in the liver weeks or months after inoculation, causing further blood-stage infection and potential onward transmission. Estimates of the force of blood-stage infections arising from primary infections and relapses are important for designing intervention strategies. However, in endemic settings their relative contributions are unclear. Infections are frequently asymptomatic, many individuals harbor multiple infections, and while high-resolution genotyping of blood samples enables individual infections to be distinguished, primary infections and relapses cannot be identified. We develop a model and fit it to longitudinal genotyping data from children in Papua New Guinea to estimate the incidence and seasonality of P vivax primary infection and relapse. The children, aged one to three years at enrolment, were followed up over 16 months with routine surveys every two months. Blood samples were taken at the routine visits and at other times if the child was ill. Samples positive by microscopy or a molecular method for species detection were genotyped using high-resolution capillary electrophoresis for P vivax MS16 and msp1F3, and P falciparum msp2. The data were summarized as longitudinal patterns of success or failure to detect a genotype at each routine time-point (eg 001000001). We assume that the seasonality of P vivax primary infection is similar to that of P falciparum since they are transmitted by the same vectors and, because P falciparum does not have the ability to relapse, the seasonality can be estimated. Relapses occurring during the study period can be a consequence of infections occurring prior to the study: we assume that the seasonal pattern of primary infections repeats over time. We incorporate information from parasitological and entomology studies to gain leverage for estimating the parameters, and take imperfect detection into account. We estimate the force of P vivax primary

  2. Environmental enrichment for a mixed-species nocturnal mammal exhibit.

    PubMed

    Clark, Fay E; Melfi, Vicky A

    2012-01-01

    Environmental enrichment (EE) is an integral aspect of modern zoo animal management but, empirical evaluation of it is biased toward species housed in single-species groups. Nocturnal houses, where several nocturnal species are housed together, are particularly overlooked. This study investigated whether three species (nine-banded armadillos, Dasypus novemcinctus; Senegal bush babies, Galago senegalensis; two-toed sloths, Choloepus didactylus) in the nocturnal house at Paignton Zoo Environmental Park, UK could be enriched using food-based and sensory EE. Subjects were an adult male and female of each species. EE was deemed effective if it promoted target species-typical behaviors, behavioral diversity, and increased use of enriched exhibit zones. Results from generalized linear mixed models demonstrated that food-based EE elicited the most positive behavioral effects across species. One set of food-based EEs (Kong®, termite mound and hanging food) presented together was associated with a significant increase in species-typical behaviors, increased behavioral diversity, and increased use of enriched exhibit zones in armadillos and bush babies. Although one type of sensory EE (scented pine cones) increased overall exhibit use in all species, the other (rainforest sounds) was linked to a significant decrease in species-typical behavior in bush babies and sloths. There were no intra or interspecies conflicts over EE, and commensalism occurred between armadillos and bush babies. Our data demonstrate that simple food-based and sensory EE can promote positive behavioral changes in a mixed-species nocturnal mammal exhibit. We suggest that both food and sensory EE presented concurrently will maximize opportunities for naturalistic activity in all species. PMID:21387395

  3. Absence of dry season Plasmodium parasitaemia, but high rates of reported acute respiratory infection and diarrhoea in preschool-aged children in Kaédi, southern Mauritania

    PubMed Central

    2012-01-01

    Background The epidemiology of malaria in the Senegal River Gorgol valley, southern Mauritania, requires particular attention in the face of ongoing and predicted environmental and climate changes. While “malaria cases” are reported in health facilities throughout the year, past and current climatic and ecological conditions do not favour transmission in the dry season (lack of rainfall and very high temperatures). Moreover, entomological investigations in neighbouring regions point to an absence of malaria transmission in mosquito vectors in the dry season. Because the clinical signs of malaria are non-specific and overlap with those of other diseases (e.g. acute respiratory infections and diarrhoea), new research is needed to better understand malaria transmission patterns in this region to improve adaptive, preventive and curative measures. Methods We conducted a multipurpose cross-sectional survey in the city of Kaédi in April 2011 (dry season), assessing three major disease patterns, including malaria. Plasmodium spp. parasite rates were tested among children aged 6–59 months who were recruited from a random selection of households using a rapid diagnostic test and microscopic examination of Giemsa-stained thick and thin blood films. Acute respiratory infection and diarrhoea were the two other diseases investigated, administering a parental questionnaire to determine the reported prevalence among participating children. Findings No Plasmodium infection was found in any of the 371 surveyed preschool-aged children using two different diagnostic methods. Acute respiratory infections and diarrhoea were reported in 43.4% and 35.0% of the participants, respectively. About two thirds of the children with acute respiratory infections and diarrhoea required medical follow-up by a health worker. Conclusions Malaria was absent in the present dry season survey in the capital of the Gorgol valley of Mauritania, while acute respiratory infections and diarrhea were

  4. Novel Cross-Border Approaches to Optimise Identification of Asymptomatic and Artemisinin-Resistant Plasmodium Infection in Mobile Populations Crossing Cambodian Borders

    PubMed Central

    Edwards, Hannah M.; Canavati, Sara E.; Rang, Chandary; Ly, Po; Sovannaroth, Siv; Canier, Lydie; Khim, Nimol; Menard, Didier; Ashton, Ruth A.; Meek, Sylvia R.; Roca-Feltrer, Arantxa

    2015-01-01

    Background Human population movement across country borders presents a real challenge for malaria control and elimination efforts in Cambodia and its neighbouring countries. To quantify Plasmodium infection among the border-crossing population, including asymptomatic and artemisinin resistant (AR) parasites, three official border crossing points, one from each of Cambodia's borders with Thailand, Laos and Vietnam, were selected for sampling. Methods and Findings A total of 3206 participants (of 4110 approached) were recruited as they crossed the border, tested for malaria and interviewed. By real-time polymerase chain reaction (RT-PCR), 5.4% of all screened individuals were found to harbour Plasmodium parasites. The proportion was highest at the Laos border (11.5%). Overall there were 97 P. vivax (55.7%), 55 P. falciparum (31.6%), two P. malariae (1.1%) and 20 mixed infections (11.5%). Of identified infections, only 20% were febrile at the time of screening. Of the 24 P. falciparum samples where a further PCR was possible to assess AR, 15 (62.5%) had mutations in the K13 propeller domain gene, all from participants at the Laos border point. Malaria rapid diagnostic test (RDT) pLDH/HRP-2 identified a positivity rate of 3.2% overall and sensitivity compared to RT-PCR was very low (43.1%). Main individual risk factors for infection included sex, fever, being a forest-goer, poor knowledge of malaria prevention methods and previous malaria infection. Occupation, day of the week and time of crossing (morning vs. afternoon) also appeared to play an important role in predicting positive cases. Conclusions This study offers a novel approach to identify asymptomatic infections and monitor AR parasite flow among mobile and migrant populations crossing the borders. Similar screening activities are recommended to identify other hot borders and characterise potential hot spots of AR. Targeted “customised” interventions and surveillance activities should be implemented in

  5. Resistance of glucose-6-phosphate dehydrogenase deficiency to malaria: effects of fava bean hydroxypyrimidine glucosides on Plasmodium falciparum growth in culture and on the phagocytosis of infected cells.

    PubMed

    Ginsburg, H; Atamna, H; Shalmiev, G; Kanaani, J; Krugliak, M

    1996-07-01

    The balanced polymorphism of glucose-6-phosphate dehydrogenase deficiency (G6PD-) is believed to have evolved through the selective pressure of malarial combined with consumption of fava beans. The implicated fava bean constituents are the hydroxypyrimidine glucosides vicine and convicine, which upon hydrolysis of their beta-O-glucosidic bond, became protein pro-oxidants. In this work we show that the glucosides inhibit the growth of Plasmodium falciparum, increase the hexose-monophosphate shunt activity and the phagocytosis of malaria-infected erythrocytes. These activities are exacerbated in the presence of beta-glucosidase, implicating their pro-oxidant aglycones in the toxic effect, and are more pronounced in infected G6PD- erythrocytes. These results suggest that G6PD- infected erythrocytes are more susceptible to phagocytic cells, and that fava bean pro-oxidants are more efficiently suppressing parasite propagation in G6PD- erythrocytes, either by directly affecting parasite growth, or by means of enhanced phagocytic elimination of infected cells. The present findings could account for the relative resistance of G6PD- bearers to falciparum malaria, and establish a link between dietary habits and malaria in the selection of the G6PD- genotype. PMID:8710417

  6. X-ray microanalysis of Plasmodium falciparum and infected red blood cells: effects of qinghaosu and chloroquine on potassium, sodium, and phosphorus composition

    SciTech Connect

    Lee, P.; Ye, Z.; Van Dyke, K.; Kirk, R.G.

    1988-08-01

    Cryosections of human red blood cells infected by Plasmodium falciparum were analyzed by energy dispersive x-ray microanalysis to determine the elemental composition of the parasites and their red cell hosts separately. The effects of two antimalarial drugs, qinghaosu and chloroquine, on potassium, sodium, and phosphorus concentrations were studied. Malarial infection causes a decrease in potassium concentration and an increase in sodium concentration in the host red cells. The drastic change in the cation composition, however, occurs only in red cells infected by late stage parasites (late trophozoite and schizont). Red cells infected by early stage parasites (ring stage) show only small changes in sodium concentration. Furthermore, the noninfected red cells in parasitized cultures show no difference in composition from those of normal red cells. Treatment of the parasitized cultures with qinghaosu (10(-6) M) or chloroquine (10(-6) M) for 8 hr causes phosphorus concentration of both early and late parasites to decrease. An 8 hr treatment with qinghaosu also produces a reduction in potassium and an increase in sodium concentrations in early and late parasites. In contrast, 8 hr treatment with chloroquine only causes a change in the sodium and potassium concentrations of the late stage parasites and does not affect the early stage parasites.

  7. 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.

  8. Expression of Merozoite Surface Protein Markers by Plasmodium falciparum-Infected Erythrocytes in Peripheral Blood and Tissues of Children with Fatal Malaria▿

    PubMed Central

    Dobaño, Carlota; Rogerson, Stephen J.; Taylor, Terrie E.; McBride, Jana S.; Molyneux, Malcolm E.

    2007-01-01

    Sequestration of Plasmodium falciparum-infected erythrocytes is a pathological feature of fatal cerebral malaria. P. falciparum is genetically diverse among, and often within, patients. Preferential sequestration of certain genotypes might be important in pathogenesis. We compared circulating parasites with parasites sequestered in the brain, spleen, liver, and lung in the same Malawian children with fatal malaria, classifying serotypes using antibodies to merozoite surface proteins 1 and 2 and immunofluorescence in order to differentiate parasites and to quantify the proportions of each serotype. We found (i) similar distributions of various serotypes in different tissues and (ii) concordance between parasite serotypes in peripheral blood and parasite serotypes in tissues. No serotypes predominated in the brain in cerebral malaria, and parasites belonging to a single serotype did not cluster within individual vessels or within single tissues. These findings do not support the hypothesis that cerebral malaria is caused by cerebral sequestration of certain virulent types. PMID:17118989

  9. Activity of divicine in Plasmodium vinckei-infected mice has implications for treatment of favism and epidemiology of G-6-PD deficiency.

    PubMed

    Clark, I A; Cowden, W B; Hunt, N H; Maxwell, L E; Mackie, E J

    1984-07-01

    Intravenous injection of divicine into mice infected with Plasmodium vinckei rapidly killed the parasites and caused haemolysis. Degenerating parasites were observed frequently inside intact circulating erythrocytes, implying that parasite death was not a passive consequence of haemolysis. Both parasite death and haemolysis were prevented by the iron chelator desferrioxamine. In vitro, divicine caused the accumulation of malonyldialdehyde and the depletion of reduced glutathione in normal mouse erythrocytes. Desferrioxamine inhibited the former event, but not the latter. These observations support the hypothesis advanced by Huheey & Martin (Experientia, 31, 1145, 1975) to explain the patchy geographical distribution of glucose-6-phosphate dehydrogenase deficiency in historic malarial areas and also suggest that desferrioxamine, a drug already in clinical use, is a potential treatment for favism and other examples of oxidative haemolysis. PMID:6743567

  10. Parasite-specific IgM plays a significant role in the protective immune response to asexual erythrocytic stage Plasmodium chabaudi AS infection.

    PubMed

    Couper, K N; Phillips, R S; Brombacher, F; Alexander, J

    2005-05-01

    A comparison of Plasmodium chabaudi AS infection in BALB/c and BALB/c IgM-deficient mice demonstrated a protective role for IgM during infection. IgM-/- mice, unlike microMT mice, display competent B cell humoral immune responses. Increased susceptibility of IgM-/- mice was demonstrated by increased mortality, an advanced ascending infection and higher peak parasitaemia, as well as enhanced anaemia and weight loss compared with wild-type mice. The recrudescent parasitaemias were also higher in the IgM-/- mice. Early specific IgM production in P. chabaudi-infected wild-type mice was followed by IgG1 and IgG2a production, while IgG1 and IgG2a production in IgM-/- mice was preceded by specific IgD production. No protective role for natural IgM against P. chabaudi AS infection was detected as passive transfer of naïve WT serum into IgM-/- mice did not alter the disease outcome or reduce parasite numbers. Passive transfer of WT antiserum, containing predominantly specific IgM, into IgM-/- mice delayed the ascending parasitaemia and reduced mortality. Similarly, coating parasitized red blood cells with WT antiserum, but not IgM-/- antisera, prior to infection also slightly delayed the ascending acute parasitaemia. Specific IgM therefore plays an important role in the limitation of parasite replication during asexual erythrocytic P. chabaudi AS infection. PMID:15987340

  11. The effect of timing and frequency of Plasmodium falciparum infection during pregnancy on the risk of low birth weight and maternal anemia

    PubMed Central

    Kalilani, Linda; Mofolo, Innocent; Chaponda, Marjorie; Rogerson, Stephen J.; Meshnick, Steven R.

    2016-01-01

    Plasmodium falciparum infection during pregnancy causes maternal anemia and low birth weight (LBW), but the effect of frequency and timing of infection on the severity of these adverse effects is unknown. We conducted a cohort study recruiting 2462 pregnant women in Malawi. Microscopy was used to diagnose malaria at enrollment, follow-up and delivery. Birth weight and maternal hemoglobin were measured at delivery. The association between timing and frequency of infection and LBW and maternal anemia was analyzed using a binomial regression model. Compared with uninfected women, (i) the risk of LBW increased with the number of malaria episodes [one episode: prevalence ratio (PR) 1.62 (95% CI 1.07–2.46); two episodes: PR 2.41 (95% CI 1.39–4.18)]; (ii) the risk for maternal anemia increased with the number of malaria episodes [one episode: PR 1.15 (95% CI 0.86–1.54); two episodes: PR 1.82 (95% CI 1.28–2.62)]; and (iii) the risk of LBW was higher with infection in the second (PR 1.71; 95% CI 1.06–2.74) than third trimester or at delivery (PR 1.55; 95% CI 0.88–2.75). The timing and frequency of P. falciparum infection during pregnancy affected the risk of LBW but only frequency of infection had an effect on the risk of maternal anemia. Identification of gestational periods when malaria causes most adverse outcomes will facilitate effective targeting of interventions. PMID:20207387

  12. Genome-wide transcriptomic profiling of Anopheles gambiae hemocytes reveals pathogen-specific signatures upon bacterial challenge and Plasmodium berghei infection

    PubMed Central

    Baton, Luke A; Robertson, Anne; Warr, Emma; Strand, Michael R; Dimopoulos, George

    2009-01-01

    Background The mosquito Anopheles gambiae is a major vector of human malaria. Increasing evidence indicates that blood cells (hemocytes) comprise an essential arm of the mosquito innate immune response against both bacteria and malaria parasites. To further characterize the role of hemocytes in mosquito immunity, we undertook the first genome-wide transcriptomic analyses of adult female An. gambiae hemocytes following infection by two species of bacteria and a malaria parasite. Results We identified 4047 genes expressed in hemocytes, using An. gambiae genome-wide microarrays. While 279 transcripts were significantly enriched in hemocytes relative to whole adult female mosquitoes, 959 transcripts exhibited immune challenge-related regulation. The global transcriptomic responses of hemocytes to challenge with different species of bacteria and/or different stages of malaria parasite infection revealed discrete, minimally overlapping, pathogen-specific signatures of infection-responsive gene expression; 105 of these represented putative immunity-related genes including anti-Plasmodium factors. Of particular interest was the specific co-regulation of various members of the Imd and JNK immune signaling pathways during malaria parasite invasion of the mosquito midgut epithelium. Conclusion Our genome-wide transcriptomic analysis of adult mosquito hemocytes reveals pathogen-specific signatures of gene regulation and identifies several novel candidate genes for future functional studies. PMID:19500340

  13. The Costimulatory Molecule ICOS Regulates Host Th1 and Follicular Th Cell Differentiation in Response to Plasmodium chabaudi chabaudi AS Infection

    PubMed Central

    Wikenheiser, Daniel J.; Ghosh, Debopam; Kennedy, Brian

    2016-01-01

    Blood-stage Plasmodium chabaudi chabaudi AS infection requires cell- and Ab-mediated immunity to control acute and persistent infection, respectively. ICOS regulates CD4+ T cell activation and promotes the induction of follicular Th (TFH) cells, CD4+ T cells that support B cell affinity maturation within germinal centers (GCs), resulting in the production of high-affinity Abs. In this article, we demonstrate that, in response to P. c. chabaudi AS infection, the absence of ICOS resulted in an enhanced Th1 immune response that reduced peak parasitemia. Despite the absence of ICOS, CD4+ T cells were capable of expressing PD-1, B cell lymphoma 6, and CXCR5 during early infection, indicating TFH development was not impaired. However, by day 21 postinfection, Icos−/− mice accumulated fewer splenic TFHs compared with Icos+/+ mice, leading to substantially fewer GC B cells and a decrease in affinity, but not production, of parasite-specific isotype-switched Abs. Moreover, treatment of mice with anti–ICOS ligand Abs to modulate ICOS–ICOS ligand signaling revealed a requirement for ICOS in TFH differentiation only after day 6 postinfection. Ultimately, the quality and quantity of isotype-switched Abs produced in Icos−/− mice declined over time, resulting in impaired control of persistent parasitemia. Collectively, these data suggest ICOS is not required for TFH induction during P. c. chabaudi AS infection or production of isotype-switched Abs, but it is necessary for maintenance of a sustained high-affinity, protective Ab response. PMID:26667167

  14. 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. PMID:26575356

  15. Hemolytic and antimalarial effects of tight-binding glyoxalase 1 inhibitors on the host-parasite unit of erythrocytes infected with Plasmodium falciparum

    PubMed Central

    Wezena, Cletus A.; Urscher, Miriam; Vince, Robert; More, Swati S.; Deponte, Marcel

    2016-01-01

    Glyoxalases prevent the formation of advanced glycation end products by converting glycolysis-derived methylglyoxal to d-lactate with the help of glutathione. Vander Jagt and colleagues previously showed that erythrocytes release about thirty times more d-lactate after infection with the human malaria parasite Plasmodium falciparum. Functional glyoxalases in the host-parasite unit might therefore be crucial for parasite survival. Here, we determined the antimalarial and hemolytic activity of two tight-binding glyoxalase inhibitors using infected and uninfected erythrocytes. In addition, we synthesized and analyzed a set of diester derivates of both tight-binding inhibitors resulting in up to threefold lower IC50 values and an altered methemoglobin formation and hemolytic activity depending on the type of ester. Inhibitor treatments of uninfected erythrocytes revealed an extremely slow inactivation of the host cell glyoxalase, irrespective of inhibitor modifications, and a potential dispensability of the host cell enzyme for parasite survival. Our study highlights the benefits and drawbacks of different esterifications of glutathione-derived inhibitors and demonstrates the suitability of glyoxalase inhibitors as a tool for deciphering the relevance and mode of action of different glyoxalase systems in a host-parasite unit. PMID:26972115

  16. 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

    2010-01-01

    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

  17. 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

    2015-05-01

    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

  18. Hemolytic and antimalarial effects of tight-binding glyoxalase 1 inhibitors on the host-parasite unit of erythrocytes infected with Plasmodium falciparum.

    PubMed

    Wezena, Cletus A; Urscher, Miriam; Vince, Robert; More, Swati S; Deponte, Marcel

    2016-08-01

    Glyoxalases prevent the formation of advanced glycation end products by converting glycolysis-derived methylglyoxal to d-lactate with the help of glutathione. Vander Jagt and colleagues previously showed that erythrocytes release about thirty times more d-lactate after infection with the human malaria parasite Plasmodium falciparum. Functional glyoxalases in the host-parasite unit might therefore be crucial for parasite survival. Here, we determined the antimalarial and hemolytic activity of two tight-binding glyoxalase inhibitors using infected and uninfected erythrocytes. In addition, we synthesized and analyzed a set of diester derivates of both tight-binding inhibitors resulting in up to threefold lower IC50 values and an altered methemoglobin formation and hemolytic activity depending on the type of ester. Inhibitor treatments of uninfected erythrocytes revealed an extremely slow inactivation of the host cell glyoxalase, irrespective of inhibitor modifications, and a potential dispensability of the host cell enzyme for parasite survival. Our study highlights the benefits and drawbacks of different esterifications of glutathione-derived inhibitors and demonstrates the suitability of glyoxalase inhibitors as a tool for deciphering the relevance and mode of action of different glyoxalase systems in a host-parasite unit. PMID:26972115

  19. Simian malaria at two sites in the Brazilian Amazon. I--The infection rates of Plasmodium brasilianum in non-human primates.

    PubMed

    Lourenço-de-Oliveira, R; Deane, L M

    1995-01-01

    The parasite that causes simian malaria in the Brazilian Amazon, Plasmodium brasilianum, is infective to man. In this region, where humans live within and in close proximity to the forest, it was suspected that this parasite could be the cause of a zoonosis. A study was performed in the areas surrounding two hydroelectric plants in the Amazon, Balbina and Samuel, aiming at determining the zoonotic potential of this parasite. P. brasilianum was detected in, respectively, 15.8% and 9.9% of 126 and 252 primates belonging to seven and eight species examined from Balbina and Samuel. The highest malaria infection rates were found among the red-howler monkey Alouatta seniculus straminea (32.3%), the bearded-saki Chiropotes satanas chiropotes (50%) and the spider-monkey Ateles paniscus paniscus (2[1+]) from Balbina and in the squirrel-monkey Saimiri ustus (21%) and the black-faced-spider-monkey Ateles paniscus chamek (28.6%) from Samuel. PMID:8544737

  20. Counter-regulatory anti-parasite cytokine responses during concurrent Plasmodium yoelii and intestinal helminth infections in mice

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Malaria and helminth infections are two of the most prevalent parasitic diseases in tropical areas. While concomitant infection is common, mechanisms contributing to altered disease outcomes during co-infection remain poorly defined. We have previously reported exacerbation of normally non-lethal ...

  1. Antibodies to variant surface antigens of Plasmodium falciparum infected erythrocytes associated with protection from treatment failure and development of anaemia in pregnancy

    PubMed Central

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

    2009-01-01

    Background 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 opsonise IEs for phagocytic clearance, protecting women from anemia and low birth weight Methods and findings Using sera from 141 parasitemic pregnant Malawian women enrolled in a randomized trial of antimalarials and VSA-PAM-expressing CS2 IEs, we quantitated levels of IgG to VSA-PAM by flow cytometry and opsonizing antibodies by measuring uptake of IEs by THP1 promonocytes. After controlling for gravidity and antimalarial treatment, IgG against VSA-PAM was associated with decreased anemia at delivery (OR=0.66, 95% confidence interval [CI] 0.46, 0.93; P=0.018) and weakly associated with decreased parasitological failure (OR=0.78; 95% CI, 0.60, 1.03; P=0.075), especially re-infection (OR=0.73; CI, 0.53,1.01; P=0.057). Opsonizing antibodies to CS2 IE were associated with less maternal anemia. (OR=0.31, 95% CI, 0.13, 0.74; P=0.008) and treatment failure (OR=0.48; 95% CI, 0.25, 0.90; P=0.023), primarily due to recrudescent infection (OR=0.49; 95% CI, 0.21, 1.12; P=0.089). Conclusion Both IgG antibody to VSA-PAM and opsonizing antibody, a functional measure of immunity correlate with parasite clearance and less anemia in pregnancy malaria. PMID:19500037

  2. Ribose metabolism and nucleic acid synthesis in normal and glucose-6-phosphate dehydrogenase-deficient human erythrocytes infected with Plasmodium falciparum.

    PubMed Central

    Roth, E F; Ruprecht, R M; Schulman, S; Vanderberg, J; Olson, J A

    1986-01-01

    The metabolism of pentose-phosphate was investigated in Plasmodium falciparum-infected normal and glucose-6-phosphate dehydrogenase (G6PD)-deficient human red blood cells in vitro. 5'-Phosphoribosyl-1-pyrophosphate (PRPP) content of infected normal red blood cells was increased 50-60-fold at the parasite trophozoite growth stage over that of uninfected cells. The PRPP increment in infected G6PD-deficient cells at comparable stage and parasitemia was only 40% of the value in normal infected cells. Red blood cell PRPP synthetase activity did not change during the growth cycle of the parasite and was similar in both normal and G6PD-deficient cells. Reduced glutathione (GSH) content of G6PD-deficient cells under conditions of culture fell to low or undetectable levels. These low levels of GSH were shown to inhibit the function of red blood cell PRPP synthetase, which requires GSH for full activity. Measurements of the incorporation of 1-14C or 6-14C selectively labeled glucose into parasite nucleic acids revealed that in normal infected red cells, approximately 20% of the pentose was produced via the oxidation of glucose-6-phosphate, whereas in infected G6PD-deficient cells (Mediterranean type), none of the pentose was produced via the oxidative pathway. It is concluded that the low level of reduced GSH found in G6PD deficiency and the resultant partial inhibition of PRPP synthetase together with the missing oxidative pathway for ribose phosphate production can account fully for the reduced parasite growth rate in G6PD-deficient red blood cells described previously. Of these two mechanisms, the predominant one is the impaired PRPP synthetase activity due to low GSH levels in enzyme-deficient red blood cells. The contribution to the ribose-phosphate pool by the hexose monophosphate shunt is relatively minor. A co-existing oxidative stress (which is often hypothesized to mediate the destruction of parasitized red blood cells) is not required to explain growth inhibition

  3. Heterozygous mutants of TIRAP (S180L) polymorphism protect adult patients with Plasmodium falciparum infection against severe disease and mortality.

    PubMed

    Panda, Aditya K; Das, Bidyut K; Panda, Abhinash; Tripathy, Rina; Pattnaik, Sarit S; Mahto, Harishankar; Pied, Sylviane; Pathak, Sulabha; Sharma, Shobhona; Ravindran, Balachandran

    2016-09-01

    Toll-interleukin-1 receptor domain containing adapter protein (TIRAP) plays a crucial role in TLR2 and TLR4 signaling pathways. Glycosylphospatidylinositol (GPI), considered a toxin molecule of Plasmodium falciparum, interacts with TLR2 and 4 to induce an immune inflammatory response. A single nucleotide polymorphism at coding region of TIRAP (S180L) has been reported to influence TLRs signaling. In the present study, we investigated the association of TIRAP (S180L) polymorphism with susceptibility/resistance to severe P. falciparum malaria in a cohort of adult patients from India. TIRAP S180L polymorphism was typed in 347 cases of severe malaria (SM), 232 uncomplicated malaria and 150 healthy controls. Plasma levels of TNF-α was quantified by ELISA. Heterozygous mutation (S/L) conferred significant protection against MOD (multi organ dysfunction), NCSM (non-cerebral severe malaria) as well as mortality. Interestingly, homozygous mutants (L/L) had 16 fold higher susceptibility to death. TIRAP mutants (S/L and L/L) were associated with significantly higher plasma TNF-α levels compared to wild type (S/S). The results of the present study demonstrate that TIRAP S180L heterozygous mutation may protect patients against severe malaria and mortality. PMID:27166096

  4. Anopheles gambiae collagen IV genes: cloning, phylogeny and midgut expression associated with blood feeding and Plasmodium infection.

    PubMed

    Gare, D C; Piertney, S B; Billingsley, P F

    2003-07-01

    A prerequisite for understanding the role that mosquito midgut extracellular matrix molecules play in malaria parasite development is proper isolation and characterisation of the genes coding for components of the basal lamina. Here we have identified genes coding for alpha1 and alpha2 chains of collagen IV from the major malaria vector, Anopheles gambiae. Conserved sequences in the terminal NC1 domain were used to obtain partial gene sequences of this functional region, and full sequence was isolated from a pupal cDNA library. In a DNA-derived phylogeny, the alpha1 and alpha2 chains cluster with dipteran orthologs, and the alpha2 is ancestral. The expression of collagen alpha1(IV) peaked during the pupal stage of mosquito development, and was expressed continuously in the adult female following a blood meal with a further rise detected in older mosquitoes. Collagen alpha1(IV) is also upregulated when the early oocyst of Plasmodium yoelii was developing within the mosquito midgut and may contribute to a larger wound healing response. A model describing the expression of basal lamina proteins during oocyst development is presented, and we hypothesise that the development of new basal lamina between the oocyst and midgut epithelium is akin to a wound healing process. PMID:12814648

  5. In vivo antimalarial activity of essential oils from Cymbopogon citratus and Ocimum gratissimum on mice infected with Plasmodium berghei.

    PubMed

    Tchoumbougnang, F; Zollo, P H; Dagne, E; Mekonnen, Y

    2005-01-01

    The essential oils obtained by hydrodistillation from fresh leaves of Cymbopogon citratus and Ocimum gratissimum growing in Cameroon were analyzed by GC and GC/MS. The main constituents of the oil of Ocimum gratissimum were gamma-terpinene (21.9 %), beta-phellandrene (21.1 %), limonene (11.4 %) and thymol (11.2 %), while the oil of Cymbopogon citratus contained geranial (32.8 %), neral (29.0 %), myrcene (16.2 %) and beta-pinene (10.5 %). The effects of these oils on the growth of Plasmodium berghei were investigated. Both oils showed significant antimalarial activities in the four-day suppressive in vivo test in mice. At concentrations of 200, 300 and 500 mg/kg of mouse per day, the essential oil of C. citratus produced the highest activity with the respective percentages of suppression of parasitaemia: 62.1 %, 81.7 % and 86.6 %. The corresponding values for the oil of O. gratissimum at the same concentrations were 55.0 %, 75.2 % and 77.8 %, respectively. Chloroquine (10 mg/kg of mouse, positive control) had a suppressive activity of 100 %. PMID:15678368

  6. Overexpression and altered nucleocytoplasmic distribution of Anopheles ovalbumin-like SRPN10 serpins in Plasmodium-infected midgut cells.

    PubMed

    Danielli, Alberto; Barillas-Mury, Carolina; Kumar, Sanjeev; Kafatos, Fotis C; Loukeris, Thanasis G

    2005-02-01

    The design of effective, vector-based malaria transmission blocking strategies relies on a thorough understanding of the molecular and cellular interactions that occur during the parasite sporogonic cycle in the mosquito. During Plasmodium berghei invasion, transcription from the SRPN10 locus, encoding four serine protease inhibitors of the ovalbumin family, is strongly induced in the mosquito midgut. Herein we demonstrate that intense induction as well as redistribution of SRPN10 occurs specifically in the parasite-invaded midgut epithelial cells. Quantitative analysis establishes that in response to epithelial invasion, SRPN10 translocates from the nucleus to the cytoplasm and this is followed by strong SRPN10 overexpression. The invaded cells exhibit signs of apoptosis, suggesting a link between this type of intracellular serpin and epithelial damage. The SRPN10 gene products constitute a novel, robust and cell-autonomous marker of midgut invasion by ookinetes. The SRPN10 dynamics at the subcellular level confirm and further elaborate the 'time bomb' model of P. berghei invasion in both Anopheles stephensi and Anopheles gambiae. In contrast, this syndrome of responses is not elicited by mutant P. berghei ookinetes lacking the major ookinete surface proteins, P28 and P25. Molecular markers with defined expression patterns, in combination with mutant parasite strains, will facilitate dissection of the molecular mechanisms underlying vector competence and development of effective transmission blocking strategies. PMID:15659062

  7. Disrupting the mixed-species biofilm of Klebsiella pneumoniae B5055 and Pseudomonas aeruginosa PAO using bacteriophages alone or in combination with xylitol.

    PubMed

    Chhibber, Sanjay; Bansal, Shruti; Kaur, Sukhmandir

    2015-07-01

    We investigated the potential of bacteriophages alone as well as in combination with xylitol for tackling mixed-species biofilm of Pseudomonas aeruginosa and Klebsiella pneumoniae. When mixed-species biofilm was established on polycarbonate discs, P. aeruginosa formed the base layer which was physically shielded on the top by K. pneumoniae. Thereafter, mixed-species biofilm was treated with bacteriophages. K. pneumoniae-specific depolymerase-producing phage KPO1K2 caused significant reduction in the count of Klebsiella. In contrast, P. aeruginosa-specific non-depolymerase-producing phage Pa29 failed to cause any reduction in the count of Pseudomonas. However, application of both phages together resulted in significant reduction in the count of both organisms. This suggests that depolymerase produced by phage KPO1K2 hydrolysed the top layer of K. pneumoniae and guided the entry of Pa29 to reach P. aeruginosa lying underneath. This phenomenon was confirmed when K. pneumoniae-specific non-depolymerase-producing phage NDP was used along with Pa29. Pa29 could not penetrate and reach its host bacterium. Xylitol worked synergistically along with the phage, resulting in a significant decrease in counts of both organisms. Disruption of mixed species biofilm by phage and xylitol was confirmed on the basis of the amount of protein and DNA released. This phage-based approach to altering the structural pattern and disrupting the mixed species biofilm is the first of its kind. It can be used as a topical application, a coating for foreign bodies or for aerosol delivery to tackle infections where both pathogens coexist in a biofilm mode. PMID:25922418

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

    PubMed Central

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

    2015-01-01

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

  9. Humoral and cell-mediated immunity to the Plasmodium falciparum ring-infected erythrocyte surface antigen in an adult population exposed to highly endemic malaria.

    PubMed Central

    Beck, H P; Felger, I; Genton, B; Alexander, N; al-Yaman, F; Anders, R F; Alpers, M

    1995-01-01

    A parasitological and immunological survey was carried out in an area in Papua New Guinea highly endemic for malaria. Two hundred fourteen adult individuals were selected for studies to assess their immune responses against the malaria vaccine candidate ring-infected erythrocyte surface antigen (RESA). Total immunoglobulin G (IgG) antibodies directed against RESA as well as specific IgG1, IgG2, and IgG3 antibodies were determined. Humoral responses directed against RESA were frequent in all IgG subclasses. Only IgG3 responses were found to be age dependent. Total anti-RESA IgG antibodies were not correlated with protection against malaria as measured by parasite prevalence, parasite density, or health center attendance. In contrast, cytophilic antibodies (IgG1 and IgG3) were associated with reduced Plasmodium falciparum prevalence and reduced health center attendance. T-cell proliferation in general was low and very infrequent. No correlation between humoral and cellular immune responses could be found. Parasite density, parasite prevalence, and health center visits tended to be reduced in individuals with good humoral and cell-mediated immune responses. PMID:7822028

  10. 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

  11. IFN-γ and IL-21 Double Producing T Cells Are Bcl6-Independent and Survive into the Memory Phase in Plasmodium chabaudi Infection.

    PubMed

    Carpio, Victor H; Opata, Michael M; Montañez, Marelle E; Banerjee, Pinaki P; Dent, Alexander L; Stephens, Robin

    2015-01-01

    CD4 T cells are required to fight malaria infection by promoting both phagocytic activity and B cell responses for parasite clearance. In Plasmodium chabaudi infection, one specific CD4 T cell subset generates anti-parasitic IFN-γ and the antibody-promoting cytokine, IL-21. To determine the lineage of these multifunctional T cells, we followed IFN-γ+ effector T cells (Teff) into the memory phase using Ifng-reporter mice. While Ifng+ Teff expanded, the level of the Th1 lineage-determining transcription factor T-bet only peaked briefly. Ifng+ Teff also co-express ICOS, the B cell area homing molecule CXCR5, and other Tfh lineage-associated molecules including Bcl6, the transcription factor required for germinal center (GC) T follicular helper cells (Tfh) differentiation. Because Bcl6 and T-bet co-localize to the nucleus of Ifng+ Teff, we hypothesized that Bcl6 controls the Tfh-like phenotype of Ifng+ Teff cells in P. chabaudi infection. We first transferred Bcl6-deficient T cells into wildtype hosts. Bcl6-deficient T cells did not develop into GC Tfh, but they still generated CXCR5+ IFN-γ+ IL-21+ IL-10+ Teff, suggesting that this predominant population is not of the Tfh-lineage. IL-10 deficient mice, which have increased IFN-γ and T-bet expression, demonstrated expansion of both IFN-γ+ IL-21+ CXCR5+ cells and IFN-γ+ GC Tfh cells, suggesting a Th1 lineage for the former. In the memory phase, all Ifng+ T cells produced IL-21, but only a small percentage of highly proliferative Ifng+ T cells maintained a T-bethi phenotype. In chronic malaria infection, serum IFN-γ correlates with increased protection, and our observation suggests Ifng+ T cells are maintained by cellular division. In summary, we found that Ifng+ T cells are not strictly Tfh derived during malaria infection. T cells provide the host with a survival advantage when facing this well-equipped pathogen, therefore, understanding the lineage of pivotal T cell players will aid in the rational design of an

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

    PubMed

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

    2016-01-01

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

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

    PubMed Central

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

    2016-01-01

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

  14. Plasmodium falciparum Gametocyte-Specific Antibody Profiling Reveals Boosting through Natural Infection and Identifies Potential Markers of Gametocyte Exposure.

    PubMed

    Skinner, Jeff; Huang, Chiung-Yu; Waisberg, Michael; Felgner, Philip L; Doumbo, Ogobara K; Ongoiba, Aissata; Kayentao, Kassoum; Traore, Boubacar; Crompton, Peter D; Williamson, Kim C

    2015-11-01

    Malaria elimination efforts would benefit from vaccines that block transmission of Plasmodium falciparum gametocytes from humans to mosquitoes. A clear understanding of gametocyte-specific antibody responses in exposed populations could help determine whether transmission-blocking vaccines (TBV) would be boosted by natural gametocyte exposure, and also inform the development of serologic tools to monitor gametocyte exposure in populations targeted for malaria elimination. To this end, plasma was collected from Malian children and adults before and after the 6-month malaria season and probed against a microarray containing 1,204 P. falciparum proteins. Using publicly available proteomic data, we classified 91 proteins as gametocyte specific and 69 as proteins not expressed by gametocytes. The overall breadth and magnitude of gametocyte-specific IgG responses increased during the malaria season, although they were consistently lower than IgG responses to nongametocyte antigens. Notably, IgG specific for the TBV candidates Pfs48/45 and Pfs230 increased during the malaria season. In addition, IgGs specific for the gametocyte proteins Pfmdv1, Pfs16, PF3D7_1346400, and PF3D7_1024800 were detected in nearly all subjects, suggesting that seroconversion to these proteins may be a sensitive indicator of gametocyte exposure, although further studies are needed to determine the specificity and kinetics of these potential serologic markers. These findings suggest that TBV-induced immunity would be boosted through natural gametocyte exposure, and that antibody responses to particular antigens may reliably indicate gametocyte exposure. PMID:26283330

  15. Interactions between Plasmodium falciparum skeleton-binding protein 1 and the membrane skeleton of malaria-infected red blood cells

    PubMed Central

    Buckingham, Donna W.; Blanc, Lionel; Hale, John; Guo, Xinhua; Pei, Xinhong; Herrmann, Susann; Hanssen, Eric G.; Coppel, Ross L.; Mohandas, Narla; An, Xiuli; Cooke, Brian M.

    2015-01-01

    During development inside red blood cells (RBCs), Plasmodium falciparum malaria parasites export proteins that associate with the RBC membrane skeleton. These interactions cause profound changes to the biophysical properties of RBCs that underpin the often severe and fatal clinical manifestations of falciparum malaria. P. falciparum erythrocyte membrane protein 1 (PfEMP1) is one such exported parasite protein that plays a major role in malaria pathogenesis since its exposure on the parasitised RBC surface mediates their adhesion to vascular endothelium and placental syncytioblasts. En route to the RBC membrane skeleton, PfEMP1 transiently associates with Maurer's clefts (MCs), parasite-derived membranous structures in the RBC cytoplasm. We have previously shown that a resident MC protein, skeleton-binding protein 1 (SBP1), is essential for the placement of PfEMP1 onto the RBC surface and hypothesised that the function of SBP1 may be to target MCs to the RBC membrane. Since this would require additional protein interactions, we set out to identify binding partners for SBP1. Using a combination of approaches, we have defined the region of SBP1 that binds specifically to defined subdomains of two major components of the RBC membrane skeleton, protein 4.1R and spectrin. We show that these interactions serve as one mechanism to anchor MCs to the RBC membrane skeleton, however, while they appear to be necessary, they are not sufficient for the translocation of PfEMP1 onto the RBC surface. The N-terminal domain of SBP1 that resides within the lumen of MCs clearly plays an essential, but presently unknown role in this process. PMID:25883090

  16. Evasion of immunity to Plasmodium falciparum malaria by IgM masking of protective IgG epitopes in infected erythrocyte surface-exposed PfEMP1

    PubMed Central

    Barfod, Lea; Dalgaard, Michael B.; Pleman, Suzan T.; Ofori, Michael F.; Pleass, Richard J.; Hviid, Lars

    2011-01-01

    Plasmodium falciparum malaria is a major cause of mortality and severe morbidity. Its virulence is related to the parasite's ability to evade host immunity through clonal antigenic variation and tissue-specific adhesion of infected erythrocytes (IEs). The P. falciparum erythrocyte membrane protein 1 (PfEMP1) family is central to both. Here, we present evidence of a P. falciparum evasion mechanism not previously documented: the masking of PfEMP1-specific IgG epitopes by nonspecific IgM. Nonspecific IgM binding to erythrocytes infected by parasites expressing the PfEMP1 protein VAR2CSA (involved in placental malaria pathogenesis and protective immunity) blocked subsequent specific binding of human monoclonal IgG to the Duffy binding-like (DBL) domains DBL3X and DBL5ε of this PfEMP1 variant. Strikingly, a VAR2CSA-specific monoclonal antibody that binds outside these domains and can inhibit IE adhesion to the specific VAR2CSA receptor chondroitin sulfate A was unaffected. Nonspecific IgM binding protected the parasites from FcγR-dependent phagocytosis of VAR2CSA+ IEs, but it did not affect IE adhesion to chondroitin sulfate A or lead to C1q deposition on IEs. Taken together, our results indicate that the VAR2CSA affinity for nonspecific IgM has evolved to allow placenta-sequestering P. falciparum to evade acquired protective immunity without compromising VAR2CSA function or increasing IE susceptibility to complement-mediated lysis. Furthermore, functionally important PfEMP1 epitopes not prone to IgM masking are likely to be particularly important targets of acquired protective immunity to P. falciparum malaria. PMID:21746929

  17. Avian Malaria ( Plasmodium spp.) in Captive Magellanic Penguins ( Spheniscus magellanicus ) from Northern Argentina, 2010.

    PubMed

    Vanstreels, Ralph Eric Thijl; Capellino, Félix; Silveira, Patricia; Braga, Érika M; Rodríguez-Heredia, Sergio Andres; Loureiro, Julio; Catão-Dias, José Luiz

    2016-07-01

    We report two cases of lethal avian malaria in Magellanic Penguins (Spheniscus magellanicus) captive at San Clemente del Tuyú, Argentina, approximately 560 km north of Argentinean breeding colonies of Magellanic Penguins. Blood smears revealed both penguins were concurrently infected by Plasmodium (Haemamoeba) tejerai, Plasmodium (Huffia) sp., and Plasmodium (Novyella) sp. PMID:27285418

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

    PubMed Central

    2010-01-01

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

  19. Pseudomonas aeruginosa PAO1 exopolysaccharides are important for mixed species biofilm community development and stress tolerance

    PubMed Central

    Periasamy, Saravanan; Nair, Harikrishnan A. S.; Lee, Kai W. K.; Ong, Jolene; Goh, Jie Q. J.; Kjelleberg, Staffan; Rice, Scott A.

    2015-01-01

    Pseudomonas aeruginosa PAO1 produces three polysaccharides, alginate, Psl, and Pel that play distinct roles in attachment and biofilm formation for monospecies biofilms. Considerably less is known about their role in the development of mixed species biofilm communities. This study has investigated the roles of alginate, Psl, and Pel during biofilm formation of P. aeruginosa in a defined and experimentally informative mixed species biofilm community, consisting of P. aeruginosa, Pseudomonas protegens, and Klebsiella pneumoniae. Loss of the Psl polysaccharide had the biggest impact on the integration of P. aeruginosa in the mixed species biofilms, where the percent composition of the psl mutant was significantly lower (0.06%) than its wild-type (WT) parent (2.44%). In contrast, loss of the Pel polysaccharide had no impact on mixed species biofilm development. Loss of alginate or its overproduction resulted in P. aeruginosa representing 8.4 and 18.11%, respectively, of the mixed species biofilm. Dual species biofilms of P. aeruginosa and K. pneumoniae were not affected by loss of alginate, Pel, or Psl, while the mucoid P. aeruginosa strain achieved a greater biomass than its parent strain. When P. aeruginosa was grown with P. protegens, loss of the Pel or alginate polysaccharides resulted in biofilms that were not significantly different from biofilms formed by the WT PAO1. In contrast, overproduction of alginate resulted in biofilms that were comprised of 35–40% of P. aeruginosa, which was significantly higher than the WT (5–20%). Loss of the Psl polysaccharide significantly reduced the percentage composition of P. aeruginosa in dual species biofilms with P. protegens (<1%). Loss of the Psl polysaccharide significantly disrupted the communal stress resistance of the three species biofilms. Thus, the polysaccharide composition of an individual species significantly impacts mixed species biofilm development and the emergent properties of such communities. PMID

  20. Helminth infection impairs the immunogenicity of a Plasmodium falciparum DNA vaccine, but not irradiated sporozoites, in mice

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Development of an effective vaccine against malaria remains a priority. However, a significant number of individuals living in tropical areas are also likely to be co-infected with helminths, which are known to adversely affect immune responses to a number of different existing vaccines. Here we com...

  1. Mature parasite-infected erythrocyte surface antigen (MESA) of Plasmodium falciparum binds to the 30-kDa domain of protein 4.1 in malaria-infected red blood cells.

    PubMed

    Waller, Karena L; Nunomura, Wataru; An, Xiuli; Cooke, Brian M; Mohandas, Narla; Coppel, Ross L

    2003-09-01

    The Plasmodium falciparum mature parasite-infected erythrocyte surface antigen (MESA) is exported from the parasite to the infected red blood cell (IRBC) membrane skeleton, where it binds to protein 4.1 (4.1R) via a 19-residue MESA sequence. Using purified RBC 4.1R and recombinant 4.1R fragments, we show MESA binds the 30-kDa region of RBC 4.1R, specifically to a 51-residue region encoded by exon 10 of the 4.1R gene. The 3D structure of this region reveals that the MESA binding site overlaps the region of 4.1R involved in the p55, glycophorin C, and 4.1R ternary complex. Further binding studies using p55, 4.1R, and MESA showed competition between p55 and MESA for 4.1R, implying that MESA bound at the IRBC membrane skeleton may modulate normal 4.1R and p55 interactions in vivo. Definition of minimal binding domains involved in critical protein interactions in IRBCs may aid the development of novel therapies for falciparum malaria. PMID:12730097

  2. Diversity of antigens expressed on the surface of erythrocytes infected with mature Plasmodium falciparum parasites in Papua New Guinea.

    PubMed

    Forsyth, K P; Philip, G; Smith, T; Kum, E; Southwell, B; Brown, G V

    1989-09-01

    Antigens were detected on the surface of erythrocytes from children with acute falciparum malaria in Madang, Papua New Guinea. These parasite-induced erythrocyte surface antigens (PIESA) were serotyped with convalescent sera from children and hyperimmune sera from adults in parasite infected cell agglutination assays (PICAs) and by inhibition of binding of infected cells to melanoma cells. Extensive serological diversity of PIESA was demonstrated. A significant correlation between serotypes defined by reactivity of immune sera in PICA and inhibition of melanoma cell binding (MCB) was observed. This suggests that both assays measure antibody responses to the same antigen(s). Increased recognition of different PIESA specificities with age is consistent with the hypothesis that repeated exposure to malaria confers immunity against a range of PIESA serotypes and parallels the development of clinical immunity to malaria in this area of Papua New Guinea. PMID:2679156

  3. 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

  4. Membrane specific mapping and colocalization of malarial and host skeletal proteins in the Plasmodium falciparum infected erythrocyte by dual-color near-field scanning optical microscopy.

    PubMed

    Enderle, T; Ha, T; Ogletree, D F; Chemla, D S; Magowan, C; Weiss, S

    1997-01-21

    Accurate localization of proteins within the substructure of cells and cellular organelles enables better understanding of structure-function relationships, including elucidation of protein-protein interactions. We describe the use of a near-field scanning optical microscope (NSOM) to simultaneously map and detect colocalized proteins within a cell, with superresolution. The system we elected to study was that of human red blood cells invaded by the human malaria parasite Plasmodium falciparum. During intraerythrocytic growth, the parasite expresses proteins that are transported to the erythrocyte cell membrane. Association of parasite proteins with host skeletal proteins leads to modification of the erythrocyte membrane. We report on colocalization studies of parasite proteins with an erythrocyte skeletal protein. Host and parasite proteins were selectively labeled in indirect immunofluorescence antibody assays. Simultaneous dual-color excitation and detection with NSOM provided fluorescence maps together with topography of the cell membrane with subwavelength (100 nm) resolution. Colocalization studies with laser scanning confocal microscopy provided lower resolution (310 nm) fluorescence maps of cross sections through the cell. Because the two excitation colors shared the exact same near-field aperture, the two fluorescence images were acquired in perfect, pixel-by-pixel registry, free from chromatic aberrations, which contaminate laser scanning confocal microscopy measurements. Colocalization studies of the protein pairs of mature parasite-infected erythrocyte surface antigen (MESA) (parasite)/protein4.1(host) and P. falciparum histidine rich protein (PfHRP1) (parasite)/protein4.1(host) showed good real-space correlation for the MESA/protein4.1 pair, but relatively poor correlation for the PfHRP1/protein4.1 pair. These data imply that NSOM provides high resolution information on in situ interactions between proteins in biological membranes. This method of

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

    PubMed Central

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

    2013-01-01

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

  6. Oxidant stress in malaria as probed by stable nitroxide radicals in erythrocytes infected with Plasmodium berghei. The effects of primaquine and chloroquine.

    PubMed

    Deslauriers, R; Butler, K; Smith, I C

    1987-12-10

    Erythrocytes from normal mice and mice infected with the malarial parasite Plasmodium berghei reduce the water-soluble spin probes 2,2,6,6-tetramethylpiperidine-4-hydroxy-N-oxyl (TEMPOL), 2,2,6,6-tetramethylpiperidine-N-oxyl (TEMPO) and 2,2,6,6-tetramethylpiperidine-4-keto-N-oxyl (TEMPONE) at similar rates under both air and N2 atmospheres. The ESR signal of the lipid-soluble spin probe 5-doxyl-stearate is stable on incorporation into erythrocytes from normal mice. In contrast, parasitized red cells reduce this nitroxide probe, at a rate which increases with the level of parasitemia. Inhibitors of electron transport such as KCN and NaN3, increase the rate of reduction. We propose that nitroxide reduction occurs via the electron transport chain in the parasite. The antimalarial drug primaquine causes reduction of both water-soluble and lipid-soluble spin probes. This action of primaquine is independent of its ability to release H2O2 from oxyhemoglobin, and is ascribed to the ability of primaquine to accelerate flux through the hexose monophosphate shunt. The increased production of NADPH results in increased rates of reduction of the nitroxide radicals. Methylene blue, which also increases flux through the shunt, is even more effective than primaquine at reducing the nitroxides. Chloroquine has no such effect. Parasitized mice treated with chloroquine six hours prior to ESR measurements show less nitroxide reducing capacity than do untreated mice. Chloroquine is known to decrease flux through the hexose monophosphate shunt. The metabolic influences of the two antimalarial drugs are, thus, quite different. PMID:3315005

  7. Malaria Parasite-Infected Erythrocytes Secrete PfCK1, the Plasmodium Homologue of the Pleiotropic Protein Kinase Casein Kinase 1.

    PubMed

    Dorin-Semblat, Dominique; Demarta-Gatsi, Claudia; Hamelin, Romain; Armand, Florence; Carvalho, Teresa Gil; Moniatte, Marc; Doerig, Christian

    2015-01-01

    Casein kinase 1 (CK1) is a pleiotropic protein kinase implicated in several fundamental processes of eukaryotic cell biology. Plasmodium falciparum encodes a single CK1 isoform, PfCK1, that is expressed at all stages of the parasite's life cycle. We have previously shown that the pfck1 gene cannot be disrupted, but that the locus can be modified if no loss-of-function is incurred, suggesting an important role for this kinase in intra-erythrocytic asexual proliferation. Here, we report on the use of parasite lines expressing GFP- or His-tagged PfCK1 from the endogenous locus to investigate (i) the dynamics of PfCK1 localisation during the asexual cycle in red blood cells, and (ii) potential interactors of PfCK1, so as to gain insight into the involvement of the enzyme in specific cellular processes. Immunofluorescence analysis reveals a dynamic localisation of PfCK1, with evidence for a pool of the enzyme being directed to the membrane of the host erythrocyte in the early stages of infection, followed by a predominantly intra-parasite localisation in trophozoites and schizonts and association with micronemes in merozoites. Furthermore, we present strong evidence that a pool of enzymatically active PfCK1 is secreted into the culture supernatant, demonstrating that PfCK1 is an ectokinase. Our interactome experiments and ensuing kinase assays using recombinant PfCK1 to phosphorylate putative interactors in vitro suggest an involvement of PfCK1 in many cellular processes such as mRNA splicing, protein trafficking, ribosomal, and host cell invasion. PMID:26629826

  8. Malaria Parasite-Infected Erythrocytes Secrete PfCK1, the Plasmodium Homologue of the Pleiotropic Protein Kinase Casein Kinase 1

    PubMed Central

    Dorin-Semblat, Dominique; Demarta-Gatsi, Claudia; Hamelin, Romain; Armand, Florence; Carvalho, Teresa Gil; Moniatte, Marc; Doerig, Christian

    2015-01-01

    Casein kinase 1 (CK1) is a pleiotropic protein kinase implicated in several fundamental processes of eukaryotic cell biology. Plasmodium falciparum encodes a single CK1 isoform, PfCK1, that is expressed at all stages of the parasite’s life cycle. We have previously shown that the pfck1 gene cannot be disrupted, but that the locus can be modified if no loss-of-function is incurred, suggesting an important role for this kinase in intra-erythrocytic asexual proliferation. Here, we report on the use of parasite lines expressing GFP- or His-tagged PfCK1 from the endogenous locus to investigate (i) the dynamics of PfCK1 localisation during the asexual cycle in red blood cells, and (ii) potential interactors of PfCK1, so as to gain insight into the involvement of the enzyme in specific cellular processes. Immunofluorescence analysis reveals a dynamic localisation of PfCK1, with evidence for a pool of the enzyme being directed to the membrane of the host erythrocyte in the early stages of infection, followed by a predominantly intra-parasite localisation in trophozoites and schizonts and association with micronemes in merozoites. Furthermore, we present strong evidence that a pool of enzymatically active PfCK1 is secreted into the culture supernatant, demonstrating that PfCK1 is an ectokinase. Our interactome experiments and ensuing kinase assays using recombinant PfCK1 to phosphorylate putative interactors in vitro suggest an involvement of PfCK1 in many cellular processes such as mRNA splicing, protein trafficking, ribosomal, and host cell invasion. PMID:26629826

  9. Variation in Complexity of Infection and Transmission Stability between Neighbouring Populations of Plasmodium vivax in Southern Ethiopia

    PubMed Central

    Getachew, Sisay; To, Sheren; Trimarsanto, Hidayat; Thriemer, Kamala; Clark, Taane G.; Petros, Beyene; Aseffa, Abraham; Price, Ric N.; Auburn, Sarah

    2015-01-01

    Background P. vivax is an important public health burden in Ethiopia, accounting for almost half of all malaria cases. Owing to heterogeneous transmission across the country, a stronger evidence base on local transmission dynamics is needed to optimise allocation of resources and improve malaria interventions. Methodology and Principal Findings In a pilot evaluation of local level P. vivax molecular surveillance in southern Ethiopia, the diversity and population structure of isolates collected between May and November 2013 were investigated. Blood samples were collected from microscopy positive P. vivax patients recruited to clinical and cross-sectional surveys from four sites: Arbaminch, Halaba, Badawacho and Hawassa. Parasite genotyping was undertaken at nine tandem repeat markers. Eight loci were successfully genotyped in 197 samples (between 36 and 59 per site). Heterogeneity was observed in parasite diversity and structure amongst the sites. Badawacho displayed evidence of unstable transmission, with clusters of identical clonal infections. Linkage disequilibrium in Badawacho was higher (IAS = 0.32, P = 0.010) than in the other populations (IAS range = 0.01–0.02) and declined markedly after adjusting for identical infections (IAS = 0.06, P = 0.010). Other than Badawacho (HE = 0.70), population diversity was equivalently high across the sites (HE = 0.83). Polyclonal infections were more frequent in Hawassa (67%) than the other populations (range: 8–44%). Despite the variable diversity, differentiation between the sites was low (FST range: 5 x 10−3–0.03). Conclusions Marked variation in parasite population structure likely reflects differing local transmission dynamics. Parasite genotyping in these heterogeneous settings has potential to provide important complementary information with which to optimise malaria control interventions. PMID:26468643

  10. Managing livestock using animal behavior: mixed-species stocking and flerds.

    PubMed

    Anderson, D M; Fredrickson, E L; Estell, R E

    2012-08-01

    Mixed-species stocking can foster sound landscape management while offering economic and ecological advantages compared with mono-species stocking. Producers contemplating a mixed-species enterprise should reflect on several considerations before implementing this animal management strategy. Factors applicable to a particular producer's landscape must be considered together with goals and economic constraints before implementing mixed-species stocking. A major consideration when using mixed-species stocking is how to deal with predation losses, especially among small ruminants. An approach being adopted in some commercial operations capitalizes on using innate animal behaviors to form cohesive groups of two or more livestock species that consistently remain together under free-ranging conditions. These groups are referred to as flerds. The mixing of a flock of sheep and/or goats with a herd of cattle into a flerd has been shown to protect sheep and goats from coyote predation, as well as offering other husbandry advantages. Some of the added advantages include more efficient conversion of forage into animal protein. Creation of flerds, their maintenance and advantages are discussed. PMID:23217238

  11. Assembly patterns of mixed-species avian flocks in the Andes.

    PubMed

    Colorado, Gabriel J; Rodewald, Amanda D

    2015-03-01

    The relative contribution of deterministic and stochastic processes in the assembly of biotic communities is a central issue of controversy in community ecology. However, several studies have shown patterns of species segregation that are consistent with the hypothesis that deterministic factors such as competition and niche-partitioning structure species assemblages in animal communities. Community assembly provides a theoretical framework for understanding these processes, but it has been seldom applied to social aggregations within communities. In this research, we assessed patterns of non-randomness in Andean mixed-species flocks using three assembly models: (i) co-occurrence patterns; (ii) guild proportionality; and (iii) constant body-size ratios using data from 221 species of resident and Neotropical migrant birds participating in 311 mixed-species flocks at 13 regions distributed in Venezuela, Colombia, Ecuador and Peru. Significant assembly patterns for mixed-species flocks based on co-occurrence models and guild proportionality models suggest that competitive interactions play an important role in structuring this social system in the Andes. Distribution of species among foraging guilds (i.e. insectivore, frugivore, omnivore, nectivore) was generally similar among flocks, though with some regional variation. In contrast, we found little evidence that structuring of mixed-species flocks in the Andes was mediated by body size. Rather, we found greater than expected variance of body-size ratios within flocks, indicating that birds did not segregate morphologically. Overall, our findings suggest that deterministic factors associated to competitive interactions are important contributors to mixed-species flock assemblages across the Andes. PMID:25283441

  12. IL-18-induced expression of high-affinity IL-2R on murine NK cells is essential for NK-cell IFN-γ production during murine Plasmodium yoelii infection.

    PubMed

    Stegmann, Kerstin A; De Souza, J Brian; Riley, Eleanor M

    2015-12-01

    Early production of pro-inflammatory cytokines, including IFN-γ, is essential for control of blood-stage malaria infections. We have shown that IFN-γ production can be induced among human natural killer (NK) cells by coculture with Plasmodium falciparum infected erythrocytes, but the importance of this response is unclear. To further explore the role of NK cells during malaria infection, we have characterized the NK-cell response of C57BL/6 mice during lethal (PyYM) or nonlethal (Py17XNL) P. yoelii infection. Ex vivo flow cytometry revealed that NK cells are activated within 24 h of Py17XNL blood-stage infection, expressing CD25 and producing IFN-γ; this response was blunted and delayed during PyYM infection. CD25 expression and IFN-γ production were highly correlated, suggesting a causal relationship between the two responses. Subsequent in vitro experiments revealed that IL-18 signaling is essential for induction of CD25 and synergizes with IL-12 to enhance CD25 expression on splenic NK cells. In accordance with this, Py17XNL-infected erythrocytes induced NK-cell CD25 expression and IFN-γ production in a manner that is completely IL-18- and partially IL-12-dependent, and IFN-γ production is enhanced by IL-2. These data suggest that IL-2 signaling via CD25 amplifies IL-18- and IL-12-mediated NK-cell activation during malaria infection. PMID:26420375

  13. Anchoring a secreted plasmodium antigen on the surface of recombinant vaccinia virus-infected cells increases its immunogenicity.

    PubMed Central

    Langford, C J; Edwards, S J; Smith, G L; Mitchell, G F; Moss, B; Kemp, D J; Anders, R F

    1986-01-01

    We show that the subcellular location of foreign antigens expressed in recombinant vaccinia viruses influences their effectiveness as immunogens. Live recombinant viruses induced very poor antibody responses to a secreted repetitive plasmodial antigen (the S-antigen) in rabbits and mice. The poor response accords with epidemiological data suggesting that S-antigens are poorly immunogenic. Appending the transmembrane domain of a membrane immunoglobulin (immunoglobulin G1) to its carboxy terminus produced a hybrid S-antigen that was no longer secreted but was located on the surface of virus-infected cells. This recombinant virus elicited high antibody titers to the S-antigen. This approach will facilitate the use of live virus delivery systems to immunize against a wide range of foreign nonsurface antigens. Images PMID:3537732

  14. Global proteomic analysis of plasma from mice infected with Plasmodium berghei ANKA using two dimensional gel electrophoresis and matrix assisted laser desorption ionization-time of flight mass spectrometry

    PubMed Central

    2011-01-01

    Background A global proteomic strategy was used to identify proteins, which are differentially expressed in the murine model of severe malaria in the hope of facilitating future development of novel diagnostic, disease monitoring and treatment strategies. Methods Mice (4-week-old CD1 male mice) were infected with Plasmodium berghei ANKA strain, and infection allowed to establish until a parasitaemia of 30% was attained. Total plasma and albumin depleted plasma samples from infected and control (non-infected) mice were separated by two-dimensional gel electrophoresis (2-DE). After staining, the gels were imaged and differential protein expression patterns were interrogated using image analysis software. Spots of interest were then digested using trypsin and the proteins identified using matrix-assisted laser desorption and ionization-time of flight (MALDI-TOF) mass spectrometry (MS) and peptide mass fingerprinting software. Results Master gels of control and infected mice, and the corresponding albumin depleted fractions exhibited distinctly different 2D patterns comparing control and infected plasma, respectively. A wide range of proteins demonstrated altered expression including; acute inflammatory proteins, transporters, binding proteins, protease inhibitors, enzymes, cytokines, hormones, and channel/receptor-derived proteins. Conclusions Malaria-infection in mice results in a wide perturbation of the host serum proteome involving a range of proteins and functions. Of particular interest is the increased secretion of anti-inflammatory and anti apoptotic proteins. PMID:21791037

  15. Antimalarial and hepatoprotective effects of crude ethanolic extract of Lingzhi or Reishi medicinal mushroom, Ganoderma lucidum (W.Curt.:Fr.)P.Karst. (higher Basidiomycetes), in Plasmodium berghei-infected mice.

    PubMed

    Oluba, Olarewaju M; Olusola, Augustine O; Fagbohunka, Bamidele S; Onyeneke, E

    2012-01-01

    This study was aimed at investigating the in vivo antimalarial activity (using some biochemical indices) of crude aqueous extracts of the fruiting bodies of Ganoderma lucidum, a mushroom with well-established medicinal properties. A rodent malaria parasite, Plasmodium berghei (1 × 107), was inoculated intraperitoneally into Swiss albino mice. The test groups were administered G. lucidum extract and chloroquine (CQ, as standard drug), while the control groups were administered the same amount of distilled water by an intragastric tube once daily. The antimalarial activity of the extract was investigated from the suppressive, curative, and prophylactic effects of the extract on parasite growth. Serum aminotransferases (AST and ALT), alkaline phosphatase (ALP), and gamma glutamine transpeptidase (γ-GT) levels monitored following the 4-day suppressive test were significantly reduced, with a corresponding significant increase in the livers of mice treated with the extract compared with infected untreated mice. The results obtained from this study provide scientific justification in an animal model of malaria that an ethanolic extract of G. lucidum possesses potent antimalarial activity and also could help ameliorate the attendant Plasmodium-induced liver damage due to malarial infection. PMID:23510214

  16. Hemophagocytic Lymphohistiocytosis Complicating Dengue and Plasmodium vivax Coinfection

    PubMed Central

    Khurram, Muhammad; Faheem, Muhammad; Umar, Muhammad; Yasin, Asif; Qayyum, Wajeeha; Ashraf, Amna; Zahid Khan, Javeria; Hasnain Yasir, Ali; Ansari, Yusra; Asad, Muhammad; Khan, Iram; Abbas, Shuja; Rasheed, Irum; Rasool, Natasha; Bushra Khar, Hamama Tul

    2015-01-01

    Hemophagocytic lymphohistiocytosis (HLH) is a rare disorder. Dysfunction of cytotoxic T and natural killer (NK) cells causes uncontrolled activity of lymphocytes and histiocytes which leads to HLH. Infections, malignancies, and autoimmune disorders are associated with development of HLH. Dengue and Plasmodium vivax are rare causes of HLH. We report the first ever case of a young man who developed fatal HLH that complicated Dengue Hemorrhagic Fever (DHF) and Plasmodium vivax infection. PMID:26504465

  17. Rate of red blood cell destruction varies in different strains of mice infected with Plasmodium berghei-ANKA after chronic exposure

    PubMed Central

    Helegbe, Gideon Kofi; Huy, Nguyen T; Yanagi, Tetsuo; Shuaibu, Mohammed N; Yamazaki, Akiko; Kikuchi, Mihoko; Yasunami, Michio; Hirayama, Kenji

    2009-01-01

    Background Severe malaria anaemia in the semi-immune individuals in the holo-endemic area has been observed to occur at low parasite density with individual variation in the responses. Thus the following has been thought to be involved: auto-immune-mediated mechanisms of uninfected red blood cell destruction, and host genetic factors to explain the differences in individual responses under the same malaria transmission. In this study, the extent of red blood cell (RBC) destruction in different strains of semi-immune mice model at relatively low parasitaemia was studied. Methodology To generate semi-immunity, four strains of mice were taken through several cycles of infection and treatment. By means of immunofluorescent assay and ELISA, sera were screened for anti-erythrocyte auto-antibodies, and their relationship with haematological parameters and parasitaemia in the strains of semi-immune mice was investigated. Results Upon challenge with Plasmodium berghei ANKA after generating semi-immune status, different mean percentage haemoglobin (Hb) drop was observed in the mice strains (Balb/c = 47.1%; NZW = 30.05%; C57BL/6 = 28.44%; CBA = 25.1%), which occurred on different days for each strain (for Balb/c, mean period = 13.6 days; for C57BL/6, NZW, and CBA mean period = 10.6, 10.8, 10.9 days respectively). Binding of antibody to white ghost RBCs was observed in sera of the four strains of semi-immune mice by immunofluorescence. Mean percentage Hb drop per parasitaemia was highest in Balb/c (73.6), followed by C57BL/6 (8.6), CBA (6.9) and NZW (4.0), p = 0.0005. Consequently, auto-antibodies level to ghost RBC were correlated with degree of anaemia and were highest in Balb/c, when compared with the other strains, p < 0.001. Conclusion The results presented in this study seem to indicate that anti-RBC auto-antibodies may be involved in the destruction of uninfected RBC in semi-immune mice at relatively low parasite burden. Host genetic factors may also influence the

  18. 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

  19. Quantification of Plasmodium falciparum malaria from complex infections in the Peruvian Amazon using quantitative PCR of the merozoite surface protein 1, block 2 (PfMSP1-B2): in vitro dynamics reveal density-dependent interactions.

    PubMed

    Zervos, Thomas M; Hernandez, Jean N; Sutton, Patrick L; Branch, Oralee H

    2012-05-01

    The majority of Plasmodium falciparum field isolates are defined as complex infections because they contain multiple genetically distinct clones. Studying interactions between clones in complex infections in vivo and in vitro could elucidate important phenomena in malaria infection, transmission and treatment. Using quantitative PCR (qPCR) of the P. falciparum merozoite surface protein 1, block 2 (PfMSP1-B2), we provide a sensitive and efficient genotyping method. This is important for epidemiological studies because it makes it possible to study genotype-specific growth dynamics. We compared 3 PfMSP1-B2 genotyping methods by analysing 79 field isolates from the Peruvian Amazon. In vivo observations from other studies using these techniques led to the hypothesis that clones within complex infections interact. By co-culturing clones with different PfMSP1-B2 genotypes, and measuring parasitaemia using qPCR, we found that suppression of clonal expansion was a factor of the collective density of all clones present in a culture. PfMSP1-B2 qPCR enabled us to find in vitro evidence for parasite-parasite interactions and could facilitate future investigations of growth trends in naturally occurring complex infections. PMID:22339946

  20. Study on the Structure of Candida Albicans-Staphylococcus Epidermidis Mixed Species Biofilm on Polyvinyl Chloride Biomaterial.

    PubMed

    Chen, Ying; Wang, Xiao-Yan; Huang, Yun-Chao; Zhao, Guang-Qiang; Lei, Yu-Jie; Ye, Lian-Hua; Huang, Qiu-Bo; Duan, Wan-Shi

    2015-11-01

    The objective of the study was to establish an in vitro model of Candida albicans-Staphylococcus epidermidis mixed species biofilm (BF) on polyvinyl chloride (PVC) material, and to investigate the formation and the structure of mixed species BF formation using a combined approach of confocal laser scanning microscope (CLSM), scanning electron microscope (SEM), and 3D image reconstruction technique. Mixed species BF is achieved by co-incubating Staphylococcus epidermidis bacteria (ATCC35984) and Candida albicans fungal (ATCC10231) with PVC pieces in Tris-buffered saline. BF formation was examined at 2, 6, 12, 24, 48, and 72 h of co-culture. Thickness of these BFs and the number, and percentage of viable cells in BFs were measured. CT scan images of BFs were obtained using CLSM and SEM and reconstructed 3D images of mixed species BF were acquired, in an effort to examine structure of the BF. Staphylococcus epidermidis attached to various forms of candida albicans (spores, pseudohyphae, and hyphae), formed complex and dense mesh arrays. The BF is constituted of a large number of viable and dead pathogens, the surface of mixed species BF is uneven, with living pathogens predominating protrusive portions and dead pathogens aggregating in concaves. Mixed species BF formation on the surface of PVC material was found to be a dynamic process, with rapid growth being at 24 h of co-culture, maximal thickness peaked at 48 h. These mixed species BF matured at 48-72 h. Significant differences were observed in the proportion of viable cells between interior, middle, and outer layers of BFs (p < 0.05). Mixed species BF Candida albicans-Staphylococcus epidermidis is sophisticated in structure. The combined approach involving CLSM, SEM, and 3D image reconstruction technique is ideal for the investigation of mixed species BF on PVC material. PMID:27352339

  1. Natural Plasmodium infection in neotropical primates in the island of São Luís, state of Maranhão, Brazil.

    PubMed

    Figueiredo, Mayra Araguaia Pereira; Di Santi, Silvia Maria Fátima; Figueiredo, Thaysa Araguaia Pereira; Machado, Rosangela Zacarias

    2015-01-01

    The states that make up the Legal Amazon Region, which include the state of Maranhão, account for 99% of registered cases of human malaria in Brazil. It is also believed that transmission of malaria from nonhuman primates (NHP) to humans occurs in this region, because of current reports of seroepidemiological results from samples from humans and NHP coexisting in the same areas. This study aimed to make morphological, serological and molecular diagnoses of Plasmodium spp. in neotropical primates on the island of São Luís, state of Maranhão, Brazil. The diagnostic techniques used were optical microscopy, the polymerase chain reaction (PCR) and the indirect immunofluorescence assay (IFA). From June 2009 to April 2010, 70 NHP were sampled: 50 at the Wild Animal Screening Center (CETAS), located in the municipality of São Luís and 20 free-living individuals that were caught in a private reserve located in the municipality of São Jose de Ribamar, state of Maranhão. Under an optical microscope, 140 slides (two from each animal) were evaluated and five animals (7.1%) were found to be positive. IFA did not detect anti-Plasmodium spp. From PCR on the 70 animals sampled, amplified Plasmodium spp. products were observed in 13 samples, of which eight (61.5%) were from free-living animals and five (38.5%) were from animals at CETAS. PMID:26154952

  2. A Quality Control Program within a Clinical Trial Consortium for PCR Protocols To Detect Plasmodium Species

    PubMed Central

    Mayor, Alfredo; Mombo-Ngoma, Ghyslain; Kenguele, Hilaire M.; Ouédraogo, Smaïla; Ndam, Nicaise Tuikue; Mkali, Happy; Mwangoka, Grace; Valecha, Neena; Singh, Jai Prakash Narayan; Clark, Martha A.; Verweij, Jaco J.; Adegnika, Ayola Akim; Severini, Carlo; Menegon, Michela; Macete, Eusebio; Menendez, Clara; Cisteró, Pau; Njie, Fanta; Affara, Muna; Otieno, Kephas; Kariuki, Simon; ter Kuile, Feiko O.; Meshnick, Steven R.

    2014-01-01

    Malaria parasite infections that are only detectable by molecular methods are highly prevalent and represent a potential transmission reservoir. The methods used to detect these infections are not standardized, and their operating characteristics are often unknown. We designed a proficiency panel of Plasmodium spp. in order to compare the accuracy of parasite detection of molecular protocols used by labs in a clinical trial consortium. Ten dried blood spots (DBSs) were assembled that contained P. falciparum, P. vivax, P. malariae, and P. ovale; DBSs contained either a single species or a species mixed with P. falciparum. DBS panels were tested in 9 participating laboratories in a masked fashion. Of 90 tests, 68 (75.6%) were correct; there were 20 false-negative results and 2 false positives. The detection rate was 77.8% (49/63) for P. falciparum, 91.7% (11/12) for P. vivax, 83.3% (10/12) for P. malariae, and 70% (7/10) for P. ovale. Most false-negative P. falciparum results were from samples with an estimated ≤5 parasites per μl of blood. Between labs, accuracy ranged from 100% to 50%. In one lab, the inability to detect species in mixed-species infections prompted a redesign and improvement of the assay. Most PCR-based protocols were able to detect P. falciparum and P. vivax at higher densities, but these assays may not reliably detect parasites in samples with low P. falciparum densities. Accordingly, formal quality assurance for PCR should be employed whenever this method is used for diagnosis or surveillance. Such efforts will be important if PCR is to be widely employed to assist malaria elimination efforts. PMID:24740073

  3. Gigantism in honeybees: Apis cerana queens reared in mixed-species colonies

    NASA Astrophysics Data System (ADS)

    Tan, Ken; Hepburn, H. R.; He, Shaoyu; Radloff, S. E.; Neumann, P.; Fang, Xiang

    2006-07-01

    The development of animals depends on both genetic and environmental effects to a varying extent. Their relative influences can be evaluated in the social insects by raising the intracolonial diversity to an extreme in nests consisting of workers from more than one species. In this study, we studied the effects of mixed honeybee colonies of Apis mellifera and Apis cerana on the rearing of grafted queen larvae of A. cerana. A. mellifera sealed worker brood was introduced into A. cerana colonies and on emergence, the adults were accepted. Then, A. cerana larvae were grafted for queen rearing into two of these mixed-species colonies. Similarly, A. cerana larvae and A. mellifera larvae were also grafted conspecifically as controls. The success rate of A. cerana queen rearing in the test colonies was 64.5%, surpassing all previous attempts at interspecific queen rearing. After emergence, all virgin queens obtained from the three groups ( N=90) were measured morphometrically. The A. cerana queens from the mixed-species colonies differed significantly in size and pigmentation from the A. cerana control queens and closely approximated the A. mellifera queens. It is inferred that these changes in the A. cerana queens reared in the mixed-species colonies can be attributed to feeding by heterospecific nurse bees and/or chemical differences in royal jelly. Our data show a strong impact of environment on the development of queens. The results further suggest that in honeybees the cues for brood recognition can be learned by heterospecific workers after eclosion, thereby providing a novel analogy to slave making in ants.

  4. Streptococcus mutans protein synthesis during mixed-species biofilm development by high-throughput quantitative proteomics.

    PubMed

    Klein, Marlise I; Xiao, Jin; Lu, Bingwen; Delahunty, Claire M; Yates, John R; Koo, Hyun

    2012-01-01

    Biofilms formed on tooth surfaces are comprised of mixed microbiota enmeshed in an extracellular matrix. Oral biofilms are constantly exposed to environmental changes, which influence the microbial composition, matrix formation and expression of virulence. Streptococcus mutans and sucrose are key modulators associated with the evolution of virulent-cariogenic biofilms. In this study, we used a high-throughput quantitative proteomics approach to examine how S. mutans produces relevant proteins that facilitate its establishment and optimal survival during mixed-species biofilms development induced by sucrose. Biofilms of S. mutans, alone or mixed with Actinomyces naeslundii and Streptococcus oralis, were initially formed onto saliva-coated hydroxyapatite surface under carbohydrate-limiting condition. Sucrose (1%, w/v) was then introduced to cause environmental changes, and to induce biofilm accumulation. Multidimensional protein identification technology (MudPIT) approach detected up to 60% of proteins encoded by S. mutans within biofilms. Specific proteins associated with exopolysaccharide matrix assembly, metabolic and stress adaptation processes were highly abundant as the biofilm transit from earlier to later developmental stages following sucrose introduction. Our results indicate that S. mutans within a mixed-species biofilm community increases the expression of specific genes associated with glucan synthesis and remodeling (gtfBC, dexA) and glucan-binding (gbpB) during this transition (P<0.05). Furthermore, S. mutans up-regulates specific adaptation mechanisms to cope with acidic environments (F1F0-ATPase system, fatty acid biosynthesis, branched chain amino acids metabolism), and molecular chaperones (GroEL). Interestingly, the protein levels and gene expression are in general augmented when S. mutans form mixed-species biofilms (vs. single-species biofilms) demonstrating fundamental differences in the matrix assembly, survival and biofilm maintenance in the

  5. Subsocial behaviour and brood adoption in mixed-species colonies of two theridiid spiders

    NASA Astrophysics Data System (ADS)

    Grinsted, Lena; Agnarsson, Ingi; Bilde, Trine

    2012-12-01

    Cooperation and group living often evolves through kin selection. However, associations between unrelated organisms, such as different species, can evolve if both parties benefit from the interaction. Group living is rare in spiders, but occurs in cooperative, permanently social spiders, as well as in territorial, colonial spiders. Mixed species spider colonies, involving closely related species, have rarely been documented. We examined social interactions in newly discovered mixed-species colonies of theridiid spiders on Bali, Indonesia. Our aim was to test the degree of intra- and interspecific tolerance, aggression and cooperation through behavioural experiments and examine the potential for adoption of foreign brood. Morphological and genetic analyses confirmed that colonies consisted of two related species Chikunia nigra (O.P. Cambridge, 1880) new combination (previously Chrysso nigra) and a yet undescribed Chikunia sp. Females defended territories and did not engage in cooperative prey capture, but interestingly, both species seemed to provide extended maternal care of young and indiscriminate care for foreign brood. Future studies may reveal whether these species adopt only intra-specific young, or also inter-specifically. We classify both Chikunia species subsocial and intra- and interspecifically colonial, and discuss the evolutionary significance of a system where one or both species may potentially benefit from mutual tolerance and brood adoption.

  6. Application of SPECT/CT imaging system and radiochemical analysis for investigation of blood kinetics and tissue distribution of radiolabeled plumbagin in healthy and Plasmodium berghei-infected mice.

    PubMed

    Sumsakul, W; Karbwang, J; Na-Bangchang, K

    2016-02-01

    Plumbagin is a derivative of napthoquinone which is isolated from the roots of plants in several families. These compound exhibits a wide range of biological and pharmacological activities including antimalarial, antibacterial, antifungal, and anticancer activities. The aim of the study was to investigate blood kinetics and tissue distribution of plumbagin in healthy and Plasmodium berghei-infected mice using Single-Photon Emission Computed Tomography/Computed Tomography (SPECT/CT) and radiochemical analysis by gamma counter. Plumbagin was labeled with (99m)technetium and the reducing agent stannous chloride dihydrate (50 μg/ml) at pH 6.5. Blood kinetics and tissue distribution of the radiolabeled plumbagin were investigated in healthy and P. berghei-infected mice (2 males and 2 females for each experimental group). In vitro and in vivo stability of plumbagin complex suggested satisfactory stability profiles of (99m)Tc-plumbagin complex in plasma and normal saline (92.21-95.47%) within 24 h. Significant difference in blood kinetics parameters (Cmax, AUC, t1/2, MRT, Vd, and CL) were observed between P. berghei-infected and healthy mice. The labeled complex distributed to all organs of both healthy and infected mice but with high intensity in liver, followed by lung, stomach, large intestine and kidney. Accumulation in spleen was markedly noticeable in the infected mice. Plumbagin-labeled complex was rapidly cleared from blood and major routes of excretion were hepatobiliary and pulmonary routes. In P. berghei-infected mice, t1/2 was significantly decreased, while Vd and CL were increased compared with healthy mice. Result suggests that malaria disease state influenced the pharmacokinetics and disposition of plumbagin. SPECT/CT imaging with radiolabeled (99m)Tc is a viable non-invasive technique that can be applied for investigation of kinetics and biodistribution of plumbagin in animal models. PMID:26713669

  7. Plasmodium vivax Transmission in Africa

    PubMed Central

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

    2015-01-01

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

  8. Plasmodium vivax Transmission in Africa.

    PubMed

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

    2015-11-01

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

  9. The Robust and Modulated Biomarker Network Elicited by the Plasmodium vivax Infection Is Mainly Mediated by the IL-6/IL-10 Axis and Is Associated with the Parasite Load

    PubMed Central

    Guimarães da Costa, Allyson; do Valle Antonelli, Lis Ribeiro; Augusto Carvalho Costa, Pedro; Paulo Diniz Pimentel, João; Garcia, Nadja Pinto; Monteiro Tarragô, Andréa; Socorro Lopes dos Santos, Maria do Perpétuo; Nogueira, Paulo Afonso; Hekcmann, Maria Izabel Ovellar; Sadahiro, Aya; Teixeira-Carvalho, Andréa; Martins-Filho, Olindo Assis; Malheiro, Adriana

    2014-01-01

    Background. Recent studies have shown that the inflammatory process, including the biomarker production, and the intense activation of innate immune responses are greater in the malaria caused by Plasmodium vivax than other species. Here, we examined the levels of serum biomarkers and their interaction during acute malaria. Material and Methods. Blood samples were collected from P. vivax-infected patients at admission and from healthy donors. Levels of serum biomarkers were measured by Cytometric Bead Assay or ELISA. Results. P. vivax infection triggered the production of both inflammatory and regulatory biomarkers. Levels of IL-6, CXCL-8, IFN-γ, IL-5, and IL-10 were higher in P. vivax-infected patients than in healthy donors. On the other hand, malaria patients produced lower levels of TNF-α, IL-12p70, and IL-2 than healthy individuals. While the levels of IL-10 and IL-6 were found independent on the number of malaria episodes, higher levels of these cytokines were seen in patients with higher parasite load. Conclusion. A mixed pattern of proinflammatory and regulatory biomarkers is produced in P. vivax malaria. Analysis of biomarker network suggests that IL-10 and IL-6 are a robust axis in malaria patients and that this interaction seems to be associated with the parasite load. PMID:24741587

  10. Culturing oil sands microbes as mixed species communities enhances ex situ model naphthenic acid degradation

    PubMed Central

    Demeter, Marc A.; Lemire, Joseph A.; Yue, Gordon; Ceri, Howard; Turner, Raymond J.

    2015-01-01

    Oil sands surface mining for bitumen results in the formation of oil sands process water (OSPW), containing acutely toxic naphthenic acids (NAs). Potential exists for OSPW toxicity to be mitigated by aerobic degradation of the NAs by microorganisms indigenous to the oil sands tailings ponds, the success of which is dependent on the methods used to exploit the metabolisms of the environmental microbial community. Having hypothesized that the xenobiotic tolerant biofilm mode-of-life may represent a feasible way to harness environmental microbes for ex situ treatment of OSPW NAs, we aerobically grew OSPW microbes as single and mixed species biofilm and planktonic cultures under various conditions for the purpose of assaying their ability to tolerate and degrade NAs. The NAs evaluated were a diverse mixture of eight commercially available model compounds. Confocal microscopy confirmed the ability of mixed and single species OSPW cultures to grow as biofilms in the presence of the NAs evaluated. qPCR enumeration demonstrated that the addition of supplemental nutrients at concentrations of 1 g L-1 resulted in a more numerous population than 0.001 g L-1 supplementation by approximately 1 order of magnitude. GC-FID analysis revealed that mixed species cultures (regardless of the mode of growth) are the most effective at degrading the NAs tested. All constituent NAs evaluated were degraded below detectable limits with the exception of 1-adamantane carboxylic acid (ACA); subsequent experimentation with ACA as the sole NA also failed to exhibit degradation of this compound. Single species cultures degraded select few NA compounds. The degradation trends highlighted many structure-persistence relationships among the eight NAs tested, demonstrating the effect of side chain configuration and alkyl branching on compound recalcitrance. Of all the isolates, the Rhodococcus spp. degraded the greatest number of NA compounds, although still less than the mixed species cultures

  11. Collective decision making and social interaction rules in mixed-species flocks of songbirds.

    PubMed

    Farine, Damien R; Aplin, Lucy M; Garroway, Colin J; Mann, Richard P; Sheldon, Ben C

    2014-09-01

    Associations in mixed-species foraging groups are common in animals, yet have rarely been explored in the context of collective behaviour. Despite many investigations into the social and ecological conditions under which individuals should form groups, we still know little about the specific behavioural rules that individuals adopt in these contexts, or whether these can be generalized to heterospecifics. Here, we studied collective behaviour in flocks in a community of five species of woodland passerine birds. We adopted an automated data collection protocol, involving visits by RFID-tagged birds to feeding stations equipped with antennae, over two winters, recording 91 576 feeding events by 1904 individuals. We demonstrated highly synchronized feeding behaviour within patches, with birds moving towards areas of the patch with the largest proportion of the flock. Using a model of collective decision making, we then explored the underlying decision rule birds may be using when foraging in mixed-species flocks. The model tested whether birds used a different decision rule for conspecifics and heterospecifics, and whether the rules used by individuals of different species varied. We found that species differed in their response to the distribution of conspecifics and heterospecifics across foraging patches. However, simulating decisions using the different rules, which reproduced our data well, suggested that the outcome of using different decision rules by each species resulted in qualitatively similar overall patterns of movement. It is possible that the decision rules each species uses may be adjusted to variation in mean species abundance in order for individuals to maintain the same overall flock-level response. This is likely to be important for maintaining coordinated behaviour across species, and to result in quick and adaptive flock responses to food resources that are patchily distributed in space and time. PMID:25214653

  12. Benefits to satellite members in mixed-species foraging groups: an experimental analysis.

    PubMed

    Dolby; Grubb jr TC

    1998-08-01

    Hypotheses proposed to explain the formation of mixed-species foraging groups have focused on both foraging and antipredation benefits. Mixed-species flocks of bark-foraging birds form during the winter in the eastern deciduous forests of North America. These flocks are composed of two parid nuclear species, tufted titmice, Baeolophus bicolor, and either Carolina or black-capped chickadees, Poecile carolinensis or P. atricapillus, and several satellite species including downy woodpeckers, Picoides pubescens, and white-breasted nuthatches, Sitta carolinensis. The parid nuclear species seem to act as flock leaders and are closely followed by the satellite species. To elucidate what advantages downy woodpeckers and white-breasted nuthatches gain by flocking with parids, we removed parids from eight Ohio woodlots isolated by surrounding agricultural fields and compared the woodpeckers and nuthatches in these woodlots to those in eight controls. We tested four predictions generated by group-foraging hypotheses: compared with controls, satellite birds in treatment woodlots should (1) forage more in microclimates that reduce metabolic costs, (2) increase their vigilance, (3) exhibit reduced nutritional condition and (4) exhibit higher mortality rates. As predicted, female downy woodpeckers in treatment woodlots tended to forage in locations that were more sheltered from wind, presumably thereby reducing metabolic costs. Treatment males and females of both species significantly increased their vigilance. Finally, in the absence of parids, male nuthatches showed significantly reduced nutritional condition according to ptilochronology analysis of feathers grown during the experimental manipulation, and tended to exhibit increased mortality Copyright 1998 The Association for the Study of Animal Behaviour PMID:9787042

  13. Collective decision making and social interaction rules in mixed-species flocks of songbirds

    PubMed Central

    Farine, Damien R.; Aplin, Lucy M.; Garroway, Colin J.; Mann, Richard P.; Sheldon, Ben C.

    2014-01-01

    Associations in mixed-species foraging groups are common in animals, yet have rarely been explored in the context of collective behaviour. Despite many investigations into the social and ecological conditions under which individuals should form groups, we still know little about the specific behavioural rules that individuals adopt in these contexts, or whether these can be generalized to heterospecifics. Here, we studied collective behaviour in flocks in a community of five species of woodland passerine birds. We adopted an automated data collection protocol, involving visits by RFID-tagged birds to feeding stations equipped with antennae, over two winters, recording 91 576 feeding events by 1904 individuals. We demonstrated highly synchronized feeding behaviour within patches, with birds moving towards areas of the patch with the largest proportion of the flock. Using a model of collective decision making, we then explored the underlying decision rule birds may be using when foraging in mixed-species flocks. The model tested whether birds used a different decision rule for conspecifics and heterospecifics, and whether the rules used by individuals of different species varied. We found that species differed in their response to the distribution of conspecifics and heterospecifics across foraging patches. However, simulating decisions using the different rules, which reproduced our data well, suggested that the outcome of using different decision rules by each species resulted in qualitatively similar overall patterns of movement. It is possible that the decision rules each species uses may be adjusted to variation in mean species abundance in order for individuals to maintain the same overall flock-level response. This is likely to be important for maintaining coordinated behaviour across species, and to result in quick and adaptive flock responses to food resources that are patchily distributed in space and time. PMID:25214653

  14. Plasmodium vivax: who cares?

    PubMed Central

    Galinski, Mary R; Barnwell, John W

    2008-01-01

    More attention is being focused on malaria today than any time since the world's last efforts to achieve eradication over 40 years ago. The global community is now discussing strategies aimed at dramatically reducing malarial disease burden and the eventual eradication of all types of malaria, everywhere. As a consequence, Plasmodium vivax, which has long been neglected and mistakenly considered inconsequential, is now entering into the strategic debates taking place on malaria epidemiology and control, drug resistance, pathogenesis and vaccines. Thus, contrary to the past, the malaria research community is becoming more aware and concerned about the widespread spectrum of illness and death caused by up to a couple of hundred million cases of vivax malaria each year. This review brings these issues to light and provides an overview of P. vivax vaccine development, then and now. Progress had been slow, given inherent research challenges and minimal support in the past, but prospects are looking better for making headway in the next few years. P. vivax, known to invade the youngest red blood cells, the reticulocytes, presents a strong challenge towards developing a reliable long-term culture system to facilitate needed research. The P. vivax genome was published recently, and vivax researchers now need to coordinate efforts to discover new vaccine candidates, establish new vaccine approaches, capitalize on non-human primate models for testing, and investigate the unique biological features of P. vivax, including the elusive P. vivax hypnozoites. Comparative studies on both P. falciparum and P. vivax in many areas of research will be essential to eradicate malaria. And to this end, the education and training of future generations of dedicated "malariologists" to advance our knowledge, understanding and the development of new interventions against each of the malaria species infecting humans also will be essential. PMID:19091043

  15. Effectiveness of quinine monotherapy for the treatment of Plasmodium falciparum infection in pregnant women in Lambaréné, Gabon.

    PubMed

    Adegnika, Ayôla A; Breitling, Lutz Ph; Agnandji, Selidji T; Chai, Sanders K; Schütte, Daniela; Oyakhirome, Sunny; Schwarz, Norbert G; Grobusch, Martin P; Missinou, Michel A; Ramharter, Michael; Issifou, Saadou; Kremsner, Peter G

    2005-08-01

    Pregnant women participating in a longitudinal immuno-epidemiologic survey in Lambaréné, Gabon, and presenting with Plasmodium falciparum parasitemia at monthly blood smear examinations were offered treatment with oral 7-day quinine monotherapy according to national health guidelines. A total of 50 pregnant women were offered 7-day oral quinine sulfate 10 mg/kg thrice daily. Clinical examinations and laboratory tests were performed on Days 28 and 56 to assess the effectiveness of this standard regimen. By Day 28, the effectiveness of the 7-day quinine regimen was 60% (95% confidence interval: 46-72%). We conclude that a 7-day course of quinine has a poor effectiveness and that alternative treatment regimens for malaria in pregnant women should be assessed. PMID:16103585

  16. Effect of anti-mosquito hemolymph antibodies on fecundity and on the infectivity of malarial parasite Plasmodium vivax to Anopheles stephensi (Diptera:Insecta).

    PubMed

    Gulia, Monika; Suneja, Amita; Gakhar, Surendra K

    2002-06-01

    Rabbit antibodies to hemolymph antigens (102.5, 101, 100, 96, 88, 80, 64, 55, 43, 29, and 23 kDa) of Anopheles stephensi reduced fecundity as well as viability in An. stephensi. However, ingestion of these antibodies was not associated with a marked effect on the engorgement of mosquitoes but egg laying was significantly delayed. Antisera raised against hemolymph proteins were also used to identify cross reactive antigens/epitopes present in other tissues by Western blotting, as well as by in vivo ELISA. In addition, a significant reduction in oocyst development was also observed in An. stephensi mosquitoes that ingested anti-hemolymph antibodies along with Plasmodium vivax. The results confirmed the feasibility of targeting mosquito antigens as a novel anti-mosquito strategy, as well as confirmed the usefulness of such antigens for the development of a transmission-blocking vaccine. PMID:12195047

  17. Plasmodium species: master renovators of their host cells.

    PubMed

    de Koning-Ward, Tania F; Dixon, Matthew W A; Tilley, Leann; Gilson, Paul R

    2016-08-01

    Plasmodium parasites, the causative agents of malaria, have developed elaborate strategies that they use to survive and thrive within different intracellular environments. During the blood stage of infection, the parasite is a master renovator of its erythrocyte host cell, and the changes in cell morphology and function that are induced by the parasite promote survival and contribute to the pathogenesis of severe malaria. In this Review, we discuss how Plasmodium parasites use the protein trafficking motif Plasmodium export element (PEXEL), protease-mediated polypeptide processing, a novel translocon termed the Plasmodium translocon of exported proteins (PTEX) and exomembranous structures to export hundreds of proteins to discrete subcellular locations in the host erythrocytes, which enables the parasite to gain access to vital nutrients and to evade the immune defence mechanisms of the host. PMID:27374802

  18. Plasmodium knowlesi: the emerging zoonotic malaria parasite.

    PubMed

    Antinori, Spinello; Galimberti, Laura; Milazzo, Laura; Corbellino, Mario

    2013-02-01

    Plasmodium knowlesi was initially identified in the 30s as a natural Plasmodium of Macaca fascicularis monkey also capable of experimentally infecting humans. It gained a relative notoriety in the mid-30s as an alternative to Plasmodium vivax in the treatment of the general paralysis of the insane (neurosyphilis). In 1965 the first natural human infection was described in a US military surveyor coming back from the Pahang jungle of the Malaysian peninsula. P. knowlesi was again brought to the attention of the medical community when in 2004, Balbir Singh and his co-workers reported that about 58% of malaria cases observed in the Kapit district of the Malaysian Borneo were actually caused by P. knowlesi. In the following years several reports showed that P. knowlesi is much more widespread than initially thought with cases reported across Southeast Asia. This infection should also be considered in the differential diagnosis of any febrile travellers coming back from a recent travel to forested areas of Southeast Asia. P. knowlesi can cause severe malaria with a rate of 6-9% and with a case fatality rate of 3%. Respiratory distress, acute renal failure, shock and hyperbilirubinemia are the most frequently observed complications of severe P. knowlesi malaria. Chloroquine is considered the treatment of choice of uncomplicated malaria caused by P. knowlesi. PMID:23088834

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

    PubMed Central

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

    2006-01-01

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

  20. Average atom transport properties for pure and mixed species in the hot and warm dense matter regimes

    SciTech Connect

    Starrett, C. E.; Kress, J. D.; Collins, L. A.; Hanson, D. E.; Clerouin, J.; Recoules, V.

    2012-10-15

    The Kubo-Greenwood formulation for calculation of optical conductivities with an average atom model is extended to calculate thermal conductivities. The method is applied to species and conditions of interest for inertial confinement fusion. For the mixed species studied, the partial pressure mixing rule is used. Results including pressures, dc, and thermal conductivities are compared to ab initio calculations. Agreement for pressures is good, for both the pure and mixed species. For conductivities, it is found that the ad hoc renormalization method with line broadening, described in the text, gives best agreement with the ab initio results. However, some disagreement is found and the possible reasons for this are discussed.

  1. Cranberry Flavonoids Modulate Cariogenic Properties of Mixed-Species Biofilm through Exopolysaccharides-Matrix Disruption.

    PubMed

    Kim, Dongyeop; Hwang, Geelsu; Liu, Yuan; Wang, Yifei; Singh, Ajay P; Vorsa, Nicholi; Koo, Hyun

    2015-01-01

    The exopolysaccharides (EPS) produced by Streptococcus mutans-derived glucosyltransferases (Gtfs) are essential virulence factors associated with the initiation of cariogenic biofilms. EPS forms the core of the biofilm matrix-scaffold, providing mechanical stability while facilitating the creation of localized acidic microenvironments. Cranberry flavonoids, such as A-type proanthocyanidins (PACs) and myricetin, have been shown to inhibit the activity of Gtfs and EPS-mediated bacterial adhesion without killing the organisms. Here, we investigated whether a combination of cranberry flavonoids disrupts EPS accumulation and S. mutans survival using a mixed-species biofilm model under cariogenic conditions. We also assessed the impact of cranberry flavonoids on mechanical stability and the in situ pH at the biofilm-apatite interface. Topical application of an optimized combination of PACs oligomers (100-300 μM) with myricetin (2 mM) twice daily was used to simulate treatment regimen experienced clinically. Treatments with cranberry flavonoids effectively reduced the insoluble EPS content (>80% reduction vs. vehicle-control; p<0.001), while hindering S. mutans outgrowth within mixed-species biofilms. As a result, the 3D architecture of cranberry-treated biofilms was severely compromised, showing a defective EPS-matrix and failure to develop microcolonies on the saliva-coated hydroxyapatite (sHA) surface. Furthermore, topical applications of cranberry flavonoids significantly weaken the mechanical stability of the biofilms; nearly 90% of the biofilm was removed from sHA surface after exposure to a shear stress of 0.449 N/m2 (vs. 36% removal in vehicle-treated biofilms). Importantly, in situ pH measurements in cranberry-treated biofilms showed significantly higher pH values (5.2 ± 0.1) at the biofilm-apatite interface vs. vehicle-treated biofilms (4.6 ± 0.1). Altogether, the data provide important insights on how cranberry flavonoids treatments modulate virulence

  2. Cranberry Flavonoids Modulate Cariogenic Properties of Mixed-Species Biofilm through Exopolysaccharides-Matrix Disruption

    PubMed Central

    Kim, Dongyeop; Hwang, Geelsu; Liu, Yuan; Wang, Yifei; Singh, Ajay P.; Vorsa, Nicholi; Koo, Hyun

    2015-01-01

    The exopolysaccharides (EPS) produced by Streptococcus mutans-derived glucosyltransferases (Gtfs) are essential virulence factors associated with the initiation of cariogenic biofilms. EPS forms the core of the biofilm matrix-scaffold, providing mechanical stability while facilitating the creation of localized acidic microenvironments. Cranberry flavonoids, such as A-type proanthocyanidins (PACs) and myricetin, have been shown to inhibit the activity of Gtfs and EPS-mediated bacterial adhesion without killing the organisms. Here, we investigated whether a combination of cranberry flavonoids disrupts EPS accumulation and S. mutans survival using a mixed-species biofilm model under cariogenic conditions. We also assessed the impact of cranberry flavonoids on mechanical stability and the in situ pH at the biofilm-apatite interface. Topical application of an optimized combination of PACs oligomers (100–300 μM) with myricetin (2 mM) twice daily was used to simulate treatment regimen experienced clinically. Treatments with cranberry flavonoids effectively reduced the insoluble EPS content (>80% reduction vs. vehicle-control; p<0.001), while hindering S. mutans outgrowth within mixed-species biofilms. As a result, the 3D architecture of cranberry-treated biofilms was severely compromised, showing a defective EPS-matrix and failure to develop microcolonies on the saliva-coated hydroxyapatite (sHA) surface. Furthermore, topical applications of cranberry flavonoids significantly weaken the mechanical stability of the biofilms; nearly 90% of the biofilm was removed from sHA surface after exposure to a shear stress of 0.449 N/m2 (vs. 36% removal in vehicle-treated biofilms). Importantly, in situ pH measurements in cranberry-treated biofilms showed significantly higher pH values (5.2 ± 0.1) at the biofilm-apatite interface vs. vehicle-treated biofilms (4.6 ± 0.1). Altogether, the data provide important insights on how cranberry flavonoids treatments modulate virulence

  3. Structure and dynamics of mixed-species flocks in a Hawaiian rain forest

    USGS Publications Warehouse

    Hart, P.J.; Freed, L.A.

    2003-01-01

    Mixed-species flocks of native and introduced birds were studied for four years in an upper elevation Hawaiian rain forest. Those flocks were characterized by strong seasonality, large size, low species richness, high intraspecific abundance, a lack of migrants, and a general lack of territoriality or any sort of dominance hierarchy. There was high variability among years in patterns of occurrence at the species level, and high variability within years at the individual level. These flocks are loosely structured social groupings with apparently open membership. The fluid, unstable movement patterns, high degree of variability in size and composition, and lack of positive interspecific associations are not consistent with the "foraging enhancement" hypothesis for flocking. Two resident, endangered insectivores, the Akepa (Loxops coccineus) and Hawaii Creeper (Oreomystis mana) served as "nuclear" species. Flock composition was compared between two study sites that differed significantly in density of these two nuclear species. Flock size was similar at the two sites, primarily because the nuclear species were over-represented relative to their density. This observation suggests that birds are attempting to achieve a more optimal flock size at the lower density site.

  4. Toward a scalable quantum computing architecture with mixed species ion chains

    NASA Astrophysics Data System (ADS)

    Wright, John; Auchter, Carolyn; Chou, Chen-Kuan; Graham, Richard D.; Noel, Thomas W.; Sakrejda, Tomasz; Zhou, Zichao; Blinov, Boris B.

    2016-01-01

    We report on progress toward implementing mixed ion species quantum information processing for a scalable ion-trap architecture. Mixed species chains may help solve several problems with scaling ion-trap quantum computation to large numbers of qubits. Initial temperature measurements of linear Coulomb crystals containing barium and ytterbium ions indicate that the mass difference does not significantly impede cooling at low ion numbers. Average motional occupation numbers are estimated to be bar{n} ≈ 130 quanta per mode for chains with small numbers of ions, which is within a factor of three of the Doppler limit for barium ions in our trap. We also discuss generation of ion-photon entanglement with barium ions with a fidelity of F ≥ 0.84 , which is an initial step towards remote ion-ion coupling in a more scalable quantum information architecture. Further, we are working to implement these techniques in surface traps in order to exercise greater control over ion chain ordering and positioning.

  5. Reforestation with native mixed-species plantings in a temperate continental climate effectively sequesters and stabilizes carbon within decades.

    PubMed

    Cunningham, Shaun C; Cavagnaro, Timothy R; Mac Nally, Ralph; Paul, Keryn I; Baker, Patrick J; Beringer, Jason; Thomson, James R; Thompson, Ross M

    2015-04-01

    Reforestation has large potential for mitigating climate change through carbon sequestration. Native mixed-species plantings have a higher potential to reverse biodiversity loss than do plantations of production species, but there are few data on their capacity to store carbon. A chronosequence (5-45 years) of 36 native mixed-species plantings, paired with adjacent pastures, was measured to investigate changes to stocks among C pools following reforestation of agricultural land in the medium rainfall zone (400-800 mm yr(-1)) of temperate Australia. These mixed-species plantings accumulated 3.09 ± 0.85 t C ha(-1) yr(-1) in aboveground biomass and 0.18 ± 0.05 t C ha(-1) yr(-1) in plant litter, reaching amounts comparable to those measured in remnant woodlands by 20 years and 36 years after reforestation respectively. Soil C was slower to increase, with increases seen only after 45 years, at which time stocks had not reached the amounts found in remnant woodlands. The amount of trees (tree density and basal area) was positively associated with the accumulation of carbon in aboveground biomass and litter. In contrast, changes to soil C were most strongly related to the productivity of the location (a forest productivity index and soil N content in the adjacent pasture). At 30 years, native mixed-species plantings had increased the stability of soil C stocks, with higher amounts of recalcitrant C and higher C:N ratios than their adjacent pastures. Reforestation with native mixed-species plantings did not significantly change the availability of macronutrients (N, K, Ca, Mg, P, and S) or micronutrients (Fe, B, Mn, Zn, and Cu), content of plant toxins (Al, Si), acidity, or salinity (Na, electrical conductivity) in the soil. In this medium rainfall area, native mixed-species plantings provided comparable rates of C sequestration to local production species, with the probable additional benefit of providing better quality habitat for native biota. These results

  6. Merozoite surface protein-1 of Plasmodium yoelii fused via an oligosaccharide moiety of cholera toxin B subunit glycoprotein expressed in yeast induced protective immunity against lethal malaria infection in mice.

    PubMed

    Miyata, Takeshi; Harakuni, Tetsuya; Taira, Toki; Matsuzaki, Goro; Arakawa, Takeshi

    2012-01-20

    Methylotrophic yeast (Pichia pastoris) secreted cholera toxin B subunit (CTB) predominantly as a biologically active pentamer (PpCTB) with identical ganglioside binding affinity profiles to that of choleragenoid. Unlike choleragenoid, however, the PpCTB did not induce a footpad edema response in mice. Of the two potential glycosylation sites (NIT(4-6) and NKT(90-92)) for this protein, a N-linked oligosaccharide was identified at Asn4. The oligosaccharide, presumed to extend from the lateral circumference of the CTB pentamer ring structure, was exploited as a site-specific anchoring scaffold for the C-terminal 19-kDa merozoite surface protein-1 (MSP1-19) of the rodent malaria parasite, Plasmodium yoelii. Conjugation of MSP1-19 to PpCTB via its oligosaccharide moiety induced higher protective efficacy against lethal parasite infection than conjugation directly to the PpCTB protein body in both intranasal and subcutaneous immunization regimes. Such increased protection was potentially due to the higher antigen loading capacity of CTB achieved when the antigen was linked to the extended branches of the oligosaccharide. This might have allowed the antigen to reside in more spacious molecular environment with less steric hindrance between the constituent molecules of the fusion complex. PMID:22119928

  7. Plasmodium falciparum full life cycle and Plasmodium ovale liver stages in humanized mice.

    PubMed

    Soulard, Valérie; Bosson-Vanga, Henriette; Lorthiois, Audrey; Roucher, Clémentine; Franetich, Jean-François; Zanghi, Gigliola; Bordessoulles, Mallaury; Tefit, Maurel; Thellier, Marc; Morosan, Serban; Le Naour, Gilles; Capron, Frédérique; Suemizu, Hiroshi; Snounou, Georges; Moreno-Sabater, Alicia; Mazier, Dominique

    2015-01-01

    Experimental studies of Plasmodium parasites that infect humans are restricted by their host specificity. Humanized mice offer a means to overcome this and further provide the opportunity to observe the parasites in vivo. Here we improve on previous protocols to achieve efficient double engraftment of TK-NOG mice by human primary hepatocytes and red blood cells. Thus, we obtain the complete hepatic development of P. falciparum, the transition to the erythrocytic stages, their subsequent multiplication, and the appearance of mature gametocytes over an extended period of observation. Furthermore, using sporozoites derived from two P. ovale-infected patients, we show that human hepatocytes engrafted in TK-NOG mice sustain maturation of the liver stages, and the presence of late-developing schizonts indicate the eventual activation of quiescent parasites. Thus, TK-NOG mice are highly suited for in vivo observations on the Plasmodium species of humans. PMID:26205537

  8. Plasmodium falciparum full life cycle and Plasmodium ovale liver stages in humanized mice

    PubMed Central

    Soulard, Valérie; Bosson-Vanga, Henriette; Lorthiois, Audrey; Roucher, Clémentine; Franetich, Jean- François; Zanghi, Gigliola; Bordessoulles, Mallaury; Tefit, Maurel; Thellier, Marc; Morosan, Serban; Le Naour, Gilles; Capron, Frédérique; Suemizu, Hiroshi; Snounou, Georges; Moreno-Sabater, Alicia; Mazier, Dominique

    2015-01-01

    Experimental studies of Plasmodium parasites that infect humans are restricted by their host specificity. Humanized mice offer a means to overcome this and further provide the opportunity to observe the parasites in vivo. Here we improve on previous protocols to achieve efficient double engraftment of TK-NOG mice by human primary hepatocytes and red blood cells. Thus, we obtain the complete hepatic development of P. falciparum, the transition to the erythrocytic stages, their subsequent multiplication, and the appearance of mature gametocytes over an extended period of observation. Furthermore, using sporozoites derived from two P. ovale-infected patients, we show that human hepatocytes engrafted in TK-NOG mice sustain maturation of the liver stages, and the presence of late-developing schizonts indicate the eventual activation of quiescent parasites. Thus, TK-NOG mice are highly suited for in vivo observations on the Plasmodium species of humans. PMID:26205537

  9. The exopolysaccharide matrix modulates the interaction between 3D architecture and virulence of a mixed-species oral biofilm.

    PubMed

    Xiao, Jin; Klein, Marlise I; Falsetta, Megan L; Lu, Bingwen; Delahunty, Claire M; Yates, John R; Heydorn, Arne; Koo, Hyun

    2012-01-01

    Virulent biofilms are responsible for a range of infections, including oral diseases. All biofilms harbor a microbial-derived extracellular-matrix. The exopolysaccharides (EPS) formed on tooth-pellicle and bacterial surfaces provide binding sites for microorganisms; eventually the accumulated EPS enmeshes microbial cells. The metabolic activity of the bacteria within this matrix leads to acidification of the milieu. We explored the mechanisms through which the Streptococcus mutans-produced EPS-matrix modulates the three-dimensional (3D) architecture and the population shifts during morphogenesis of biofilms on a saliva-coated-apatitic surface using a mixed-bacterial species system. Concomitantly, we examined whether the matrix influences the development of pH-microenvironments within intact-biofilms using a novel 3D in situ pH-mapping technique. Data reveal that the production of the EPS-matrix helps to create spatial heterogeneities by forming an intricate network of exopolysaccharide-enmeshed bacterial-islets (microcolonies) through localized cell-to-matrix interactions. This complex 3D architecture creates compartmentalized acidic and EPS-rich microenvironments throughout the biofilm, which triggers the dominance of pathogenic S. mutans within a mixed-species system. The establishment of a 3D-matrix and EPS-enmeshed microcolonies were largely mediated by the S. mutans gtfB/gtfC genes, expression of which was enhanced in the presence of Actinomyces naeslundii and Streptococcus oralis. Acidic pockets were found only in the interiors of bacterial-islets that are protected by EPS, which impedes rapid neutralization by buffer (pH 7.0). As a result, regions of low pH (<5.5) were detected at specific locations along the surface of attachment. Resistance to chlorhexidine was enhanced in cells within EPS-microcolony complexes compared to those outside such structures within the biofilm. Our results illustrate the critical interaction between matrix architecture and p

  10. The Exopolysaccharide Matrix Modulates the Interaction between 3D Architecture and Virulence of a Mixed-Species Oral Biofilm

    PubMed Central

    Xiao, Jin; Klein, Marlise I.; Falsetta, Megan L.; Lu, Bingwen; Delahunty, Claire M.; Yates, John R.; Heydorn, Arne; Koo, Hyun

    2012-01-01

    Virulent biofilms are responsible for a range of infections, including oral diseases. All biofilms harbor a microbial-derived extracellular-matrix. The exopolysaccharides (EPS) formed on tooth-pellicle and bacterial surfaces provide binding sites for microorganisms; eventually the accumulated EPS enmeshes microbial cells. The metabolic activity of the bacteria within this matrix leads to acidification of the milieu. We explored the mechanisms through which the Streptococcus mutans-produced EPS-matrix modulates the three-dimensional (3D) architecture and the population shifts during morphogenesis of biofilms on a saliva-coated-apatitic surface using a mixed-bacterial species system. Concomitantly, we examined whether the matrix influences the development of pH-microenvironments within intact-biofilms using a novel 3D in situ pH-mapping technique. Data reveal that the production of the EPS-matrix helps to create spatial heterogeneities by forming an intricate network of exopolysaccharide-enmeshed bacterial-islets (microcolonies) through localized cell-to-matrix interactions. This complex 3D architecture creates compartmentalized acidic and EPS-rich microenvironments throughout the biofilm, which triggers the dominance of pathogenic S. mutans within a mixed-species system. The establishment of a 3D-matrix and EPS-enmeshed microcolonies were largely mediated by the S. mutans gtfB/gtfC genes, expression of which was enhanced in the presence of Actinomyces naeslundii and Streptococcus oralis. Acidic pockets were found only in the interiors of bacterial-islets that are protected by EPS, which impedes rapid neutralization by buffer (pH 7.0). As a result, regions of low pH (<5.5) were detected at specific locations along the surface of attachment. Resistance to chlorhexidine was enhanced in cells within EPS-microcolony complexes compared to those outside such structures within the biofilm. Our results illustrate the critical interaction between matrix architecture and p

  11. 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

  12. Similar Efficacy and Tolerability of Double-Dose Chloroquine and Artemether-Lumefantrine for Treatment of Plasmodium falciparum Infection in Guinea-Bissau: A Randomized Trial

    PubMed Central

    Kofoed, Poul-Erik; Rodrigues, Amabelia; Blessborn, Daniel; Thoft-Nielsen, Rikke; Björkman, Anders; Rombo, Lars

    2011-01-01

    Background. In 2008, Guinea-Bissau introduced artemether-lumefantrine for treatment of uncomplicated malaria. Previously, 3 times the standard dose of chloroquine, that was probably efficacious against Plasmodium falciparum with the resistance-associated chloroquine-resistance transporter (pfcrt) 76T allele, was routinely used. The present study compared the efficacy and tolerability of a double standard dose of chloroquine with the efficacy and tolerability of artemether-lumefantrine. Methods. In a randomized open-label clinical trial, artemether-lumefantrine or chloroquine (50 mg/kg) were given as 6 divided doses over 3 days to children aged 6 months - 15 years who had uncomplicated P. falciparum monoinfection. Drug concentrations were measured on day 7. P. falciparum multidrug resistance gene N86Y and pfcrt K76T alleles were identified. Results. The polymerase chain reaction–adjusted day 28 and 42 treatment efficacies were 162 (97%) of 168 and 155 (97%) of 161, respectively, for artemether-lumefantrine and 150 (95%) of 158 and 138 (94%) of 148, respectively, for chloroquine. When parasites with resistance-associated pfcrt 76T were treated, the day 28 efficacy of chloroquine was 87%. No severe drug-related adverse events were detected. Symptom resolution was similar with both treatments. Conclusions. Both treatments achieved the World Health Organization–recommended efficacy for antimalarials that will be adopted as policy. High-dose chloroquine treatment regimes should be further evaluated with the aim of assessing chloroquine as a potential partner drug to artemisinin derivatives. Clinical trials registration. NCT00426439 PMID:21148503

  13. Pathogenesis of acute avian malaria. II. Anemia mediated by a cold-active autohemagglutinin from the blood of chickens with acute Plasmodium gallinaceum infection.

    PubMed

    Soni, J L; Cox, H W

    1975-03-01

    A cold-active hemagglutinin for trypsinized human type "O" erythrocytes (CAH) from blood of chickens with acute Plasmodium gallinaceum malaria was found to be associated with 19 S and 7 S globulin fractions of malarious chicken blood, but cleavage with 2-mercaptoethanol indicated that it was primarily of the IgM class of antibody. In serologic tests CAH reacted with trypsinized erythrocytes, and anti-chicken globulin. It did not react with other of the antigens or antibodies detected in the blood of malarious chickens. When the absorbed and eluted CAH was injected into normal chickens it produced an anaphylactic-like shock and caused a 25% reduction in red blood cell counts within 48 hours. Plasma samples collected during this interval showed signs of hemolysis. Reactions of blood cells from the recipient birds with fluorescein conjugated anti-chicken globulin indicated that CAH reacted with erythrocytes. The absence of fluorescent activity 3 days after injection suggested that these erythrocytes had been removed from the circulation. When normal chickens were injected with trypsinized autologous blood cells, CAH was detected within 3 days. The agglutination test again was active at temperatures below 22 degrees C and was negative when tested at 37 degrees C. In these birds the appearance of CAH was accompanied by reductions in red blood cell counts and by hemolysis. The results of these experiments suggest that CAH was not stimulated by plasmodial parasite antigen, but rather by autoantigens, which appear to be common to heterologous animal species, and which were in some manner expressed by the presence of the intracellular parasites, or by trypsin treatment. The experiments further suggest that this autohemagglutinin was partially causal of malarial anemia. The presence of other anemia factor(s) was indicated by anemia following injection of plasma that had been absorbed free of CAH. PMID:804265

  14. Attempted integration of multiple species of turaco into a mixed-species aviary.

    PubMed

    Valuska, Annie J; Leighty, Katherine A; Ferrie, Gina M; Nichols, Valerie D; Tybor, Cheryl L; Plassé, Chelle; Bettinger, Tamara L

    2013-03-01

    Mixed-species exhibits offer a variety of benefits but can be challenging to maintain due to difficulty in managing interspecific interactions. This is particularly true when little has been documented on the behavior of the species being mixed. This was the case when we attempted to house three species of turaco (family: Musophagidae) together with other species in a walk-through aviary. To learn more about the behavior of great blue turacos, violaceous turacos, and white-bellied gray go-away birds, we supplemented opportunistic keeper observations with systematic data collection on their behavior, location, distance from other birds, and visibility to visitors. Keepers reported high levels of aggression among turacos, usually initiated by a go-away bird or a violaceous turaco. Most aggression occurred during feedings or when pairs were defending nest sites. Attempts to reduce aggression by temporarily removing birds to holding areas and reintroducing them days later were ineffective. Systematic data collection revealed increased social behavior, including aggression, during breeding season in the violaceous turacos, as well as greater location fidelity. These behavioral cues may be useful in predicting breeding behavior in the future. Ultimately, we were only able to house three species of turaco together for a short time, and prohibitively high levels of conflict occurred when pairs were breeding. We conclude that mixing these three turaco species is challenging and may not be the most appropriate housing situation for them, particularly during breeding season. However, changes in turaco species composition, sex composition, or exhibit design may result in more compatible mixed-turaco species groups. PMID:22972609

  15. Seasonal patterns of mixed species groups in large East African mammals.

    PubMed

    Kiffner, Christian; Kioko, John; Leweri, Cecilia; Krause, Stefan

    2014-01-01

    Mixed mammal species groups are common in East African savannah ecosystems. Yet, it is largely unknown if co-occurrences of large mammals result from random processes or social preferences and if interspecific associations are consistent across ecosystems and seasons. Because species may exchange important information and services, understanding patterns and drivers of heterospecific interactions is crucial for advancing animal and community ecology. We recorded 5403 single and multi-species clusters in the Serengeti-Ngorongoro and Tarangire-Manyara ecosystems during dry and wet seasons and used social network analyses to detect patterns of species associations. We found statistically significant associations between multiple species and association patterns differed spatially and seasonally. Consistently, wildebeest and zebras preferred being associated with other species, whereas carnivores, African elephants, Maasai giraffes and Kirk's dik-diks avoided being in mixed groups. During the dry season, we found that the betweenness (a measure of importance in the flow of information or disease) of species did not differ from a random expectation based on species abundance. In contrast, in the wet season, we found that these patterns were not simply explained by variations in abundances, suggesting that heterospecific associations were actively formed. These seasonal differences in observed patterns suggest that interspecific associations may be driven by resource overlap when resources are limited and by resource partitioning or anti-predator advantages when resources are abundant. We discuss potential mechanisms that could drive seasonal variation in the cost-benefit tradeoffs that underpin the formation of mixed-species groups. PMID:25470495

  16. Nest survival is influenced by parental behaviour and heterospecifics in a mixed-species colony

    USGS Publications Warehouse

    Brussee, Brianne E.; Coates, Peter S.; Hothem, Roger L.; Howe, Kristy; Casazza, Michael L.; Eadie, John M.

    2016-01-01

    Studies of avian nest success often focus on examining influences of variation in environmental and seasonal factors. However, in-depth evaluations can also incorporate variation in individual incubation behaviour to further advance our understanding of avian reproductive ecology. We examined these relationships in colonially nesting Black-crowned Night-Herons Nycticorax nycticorax using intensive video-monitoring methods to quantify incubation behaviours. We modelled nest survival as a function of both extrinsic factors and incubation behaviours over a 3-year period (2010–12) on Alcatraz Island, USA. Model-averaged parameter estimates indicated that nest survival increased as a function of greater incubation constancy (% of time spent incubating eggs within a 24-h period), and average daily precipitation throughout the nesting stage. Common Ravens Corvus corax are the only known nest predator of Night-Herons on Alcatraz Island, as on many other coastal Pacific islands. We also investigated the effects of heterospecific nesting of California Gulls Larus californicus and Western Gulls Larus occidentalis in a mixed-species colony with Night-Herons, based on nesting proximity data collected over a 2-year period (2011–12). This second analysis indicated that, in addition to incubation behaviours, nesting heterospecifics are an important factor for explaining variation in Night-Heron nest survival. However, contrary to our original expectation, we found that Night-Herons experienced increased nest survival with increasing distance from gull colony boundaries. These results may apply to other areas with multiple colonial nesting species and similar predator communities and climatic patterns.

  17. Seasonal Patterns of Mixed Species Groups in Large East African Mammals

    PubMed Central

    Kiffner, Christian; Kioko, John; Leweri, Cecilia; Krause, Stefan

    2014-01-01

    Mixed mammal species groups are common in East African savannah ecosystems. Yet, it is largely unknown if co-occurrences of large mammals result from random processes or social preferences and if interspecific associations are consistent across ecosystems and seasons. Because species may exchange important information and services, understanding patterns and drivers of heterospecific interactions is crucial for advancing animal and community ecology. We recorded 5403 single and multi-species clusters in the Serengeti-Ngorongoro and Tarangire-Manyara ecosystems during dry and wet seasons and used social network analyses to detect patterns of species associations. We found statistically significant associations between multiple species and association patterns differed spatially and seasonally. Consistently, wildebeest and zebras preferred being associated with other species, whereas carnivores, African elephants, Maasai giraffes and Kirk's dik-diks avoided being in mixed groups. During the dry season, we found that the betweenness (a measure of importance in the flow of information or disease) of species did not differ from a random expectation based on species abundance. In contrast, in the wet season, we found that these patterns were not simply explained by variations in abundances, suggesting that heterospecific associations were actively formed. These seasonal differences in observed patterns suggest that interspecific associations may be driven by resource overlap when resources are limited and by resource partitioning or anti-predator advantages when resources are abundant. We discuss potential mechanisms that could drive seasonal variation in the cost-benefit tradeoffs that underpin the formation of mixed-species groups. PMID:25470495

  18. Co-infection of Long-Term Carriers of Plasmodium falciparum with Schistosoma haematobium Enhances Protection from Febrile Malaria: A Prospective Cohort Study in Mali

    PubMed Central

    Sangala, Jules; Li, Shanping; Doumtabe, Didier; Kone, Younoussou; Traoré, Abdrahamane; Bathily, Aboudramane; Sogoba, Nafomon; Coulibaly, Michel E.; Huang, Chiung-Yu; Ongoiba, Aissata; Kayentao, Kassoum; Diallo, Mouctar; Dramane, Zongo; Nutman, Thomas B.; Crompton, Peter D.; Doumbo, Ogobara; Traore, Boubacar

    2014-01-01

    Background Malaria and schistosomiasis often overlap in tropical and subtropical countries and impose tremendous disease burdens; however, the extent to which schistosomiasis modifies the risk of febrile malaria remain