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Sample records for asymptomatic plasmodium falciparum

  1. Asymptomatic Plasmodium falciparum malaria in pregnant women in the Chittagong Hill Districts of Bangladesh.

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    Wasif A Khan

    Full Text Available BACKGROUND: Pregnancy is a known risk factor for malaria which is associated with increased maternal and infant mortality and morbidity in areas of moderate-high malaria transmission intensity where Plasmodium falciparum predominates. The nature and impact of malaria, however, is not well understood in pregnant women residing in areas of low, unstable malaria transmission where P. falciparum and P. vivax co-exist. METHODS: A large longitudinal active surveillance study of malaria was conducted in the Chittagong Hill Districts of Bangladesh. Over 32 months in 2010-2013, the period prevalence of asymptomatic P. falciparum infections was assessed by rapid diagnostic test and blood smear and compared among men, non-pregnant women and pregnant women. A subset of samples was tested for infection by PCR. Hemoglobin was assessed. Independent risk factors for malaria infection were determined using a multivariate logistic regression model. RESULTS: Total of 34 asymptomatic P. falciparum infections were detected by RDT/smear from 3,110 tests. The period prevalence of asymptomatic P. falciparum infection in pregnant women was 2.3%, compared to 0.5% in non-pregnant women and 0.9% in men. All RDT/smear positive samples that were tested by PCR were PCR-positive, and PCR detected additional 35 infections that were RDT/smear negative. In a multivariate logistic regression analysis, pregnant women had 5.4-fold higher odds of infection as compared to non-pregnant women. Malaria-positive pregnant women, though asymptomatic, had statistically lower hemoglobin than those without malaria or pregnancy. Asymptomatic malaria was found to be evenly distributed across space and time, in contrast to symptomatic infections which tend to cluster. CONCLUSION: Pregnancy is a risk factor for asymptomatic P. falciparum infection in the Chittagong Hill Districts of Bangladesh, and pregnancy and malaria interact to heighten the effect of each on hemoglobin. The even distribution

  2. Prevalence of G6PD deficiency and Plasmodium falciparum parasites in asymptomatic school children living in southern Ghana.

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    Amoah, Linda Eva; Opong, Akua; Ayanful-Torgby, Ruth; Abankwa, Joana; Acquah, Festus K

    2016-07-26

    Glucose-6-phosphate dehydrogenase (G6PD) deficiency is an X-linked genetic disorder that results in impaired enzyme activity. Although G6PD deficiency is globally distributed it is more prevalent in malaria-endemic countries. Several mutations have been identified in the G6PD gene, which alter enzyme activity. The G6PD genotype predominantly found in sub-Saharan Africa is the G6PDB (G6PD376A) with (G6PD376G) and G6PDA- (G6PD376G/202A, G6PD376G/542T, G6PD376G/680T and G6PD376G/968C) occurring at lower frequencies. The aim of this study was to identify the prevalence of G6PD deficiency and asymptomatic Plasmodium falciparum carriage in children living in southern Ghana and determine whether G6PD deficiency influences asymptomatic carriage of P. falciparum parasites. Blood samples were obtained once a month from 170 healthy Ghanaian school children aged between 5 and 12 years from Basic schools in two communities Obom and Abura with similar rainfall patterns and malaria peak seasons. G6PD enzyme activity was assessed using the qualitative G6PD RDT kit (AccessBIO). G6PD genotyping and asymptomatic parasite carriage was determined by PCR followed by restriction fragment length polymorphism (RFLP) of DNA extracted from dried blood spots. The only sub-Saharan G6PD A- allele detected was the A376G/G202A found in 12.4 % (21/170), of the children and distributed as 4.1 % (7/170) A-, 1.8 % (3/170) A-/A- homozygous deficient males and females and 6.5 % (11/170) A/A- and B/A- heterozygous deficient females. Phenotypically, 10.6 % (15/142) of the children were G6PD deficient. The asymptomatic carriage of P. falciparum by PCR was 50, 29.4, 38.2 and 38.8 % over the months of February through May 2015, respectively, and 28.8, 22.4, 25.9 and 5.9 % by microscopy during the same periods. G6PD deficiency was significantly associated with a lowered risk of PCR-estimated asymptomatic P. falciparum carriage in children during the off peak malaria season in Southern Ghana.

  3. Low prevalence of Plasmodium falciparum antigenaemia among asymptomatic HAART-treated adults in an urban cohort in Uganda

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    Castelnuovo Barbara

    2011-03-01

    Full Text Available Abstract Background Presumptive treatment of malaria is common practice in malaria endemic resource-limited settings. With the changing epidemiology of malaria and the introduction of artemisinin-based combination therapy (ACT, there is increasing need for parasite-based malaria case management to prevent unnecessary use of anti-malarial medicines, improve patient care in parasite-positive patients and identify parasite-negative patients in whom another diagnosis must be sought. Although parasitological confirmation by microscopy or alternatively by malaria rapid diagnostic tests (RDTs is recommended in all patients suspected of malaria before treatment, gaps remain in the implementation of this policy in resource-limited settings. There is need to evaluate the use of RDTs among highly active anti-retroviral therapy (HAART-treated people living with HIV (PLHIV. Methods Within an urban prospective observational research cohort of 559 PLHIV initiated on HAART and cotrimoxazole prophylaxis between April, 2004 and April, 2005, 128 patients with sustained HIV-RNA viral load Plasmodium falciparum antigen in peripheral blood. Patients with positive RDT results had microscopy performed to determine the parasite densities and were followed for clinical signs and symptoms during the subsequent six months. Results Of the 128 asymptomatic patients screened, only 5 (4% had asymptomatic P. falciparum antigenaemia. All the patients with positive HRP2 RDT results showed malaria parasites on thick film with parasite densities ranging from 02-15 malaria parasites per high power field. None of the patients with positive RDT results reported signs and symptoms of malaria infection during the subsequent six months. Conclusions In an urban area of low to moderate stable malaria transmission, there was low HRP2 P. falciparum antigenaemia among PLHIV after long-term HAART and cotrimoxazole prophylaxis. Parasite-based malaria diagnosis (PMD is recommended among PLHIV

  4. Soluble products of inflammatory reactions are not induced in children with asymptomatic Plasmodium falciparum infections

    DEFF Research Database (Denmark)

    Jakobsen, P H; McKay, V; N'Jie, R

    1996-01-01

    A proportion of children with Plasmodium falciparum infection have a high parasitaemia without accompanying fever, indicative of different clinical thresholds of parasitaemia. Higher levels of IL-10, IL-1Ra and sIL-4R but not sIL-2R were found in children with P. falciparum malaria, compared...

  5. Asymptomatic infection in individuals from the municipality of Barcelos (Brazilian Amazon is not associated with the anti-Plasmodium falciparum glycosylphosphatidylinositol antibody response

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    Larissa Rodrigues Gomes

    2013-09-01

    Full Text Available Anti-glycosylphosphatidylinositol (GPI antibodies (Abs may reflect and mediate, at least partially, anti-disease immunity in malaria by neutralising the toxic effect of parasitic GPI. Thus, we assessed the anti-GPI Ab response in asymptomatic individuals living in an area of the Brazilian Amazon that has a high level of malaria transmission. For comparative purposes, we also investigated the Ab response to a crude extract prepared from Plasmodium falciparum, the merozoite surface protein (MSP3 antigen of P. falciparum and the MSP 1 antigen of Plasmodium vivax (PvMSP1-19 in these individuals and in Angolan patients with acute malaria. Our data suggest that the Ab response against P. falciparum GPI is not associated with P. falciparum asymptomatic infection in individuals who have been chronically exposed to malaria in the Brazilian Amazon. However, this Ab response could be related to ongoing parasitaemia (as was previously shown in the Angolan patients. In addition, our data show that PvMSP1-19may be a good marker antigen to reflect previous exposure to Plasmodium in areas that have a high transmission rate of P. vivax.

  6. Multiplicity of Plasmodium falciparum infection in asymptomatic children in Senegal: relation to transmission, age and erythrocyte variants

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    Anchang Judith

    2008-01-01

    Full Text Available Abstract Background Individuals living in malaria endemic areas generally harbour multiple parasite strains. Multiplicity of infection (MOI can be an indicator of immune status. However, whether this is good or bad for the development of immunity to malaria, is still a matter of debate. This study aimed to examine the MOI in asymptomatic children between two and ten years of age and to relate it to erythrocyte variants, clinical attacks, transmission levels and other parasitological indexes. Methods Study took place in Niakhar area in Senegal, where malaria is mesoendemic and seasonal. Three hundred and seventy two asymptomatic children were included. Sickle-cell trait, G6PD deficiency (A- and Santamaria and α+-thalassaemia (-α3.7 type were determined using PCR. Multiplicity of Plasmodium falciparum infection, i.e. number of concurrent clones, was defined by PCR-based genotyping of the merozoite surface protein-2 (msp2, before and at the end of the malaria transmission season. The χ2-test, ANOVA, multivariate linear regression and logistic regression statistical tests were used for data analysis. Results MOI was significantly higher at the end of transmission season. The majority of PCR positive subjects had multiple infections at both time points (64% before and 87% after the transmission season. MOI did not increase in α-thalassaemic and G6PD mutated children. The ABO system and HbAS did not affect MOI at any time points. No association between MOI and clinical attack was observed. MOI did not vary over age at any time points. There was a significant correlation between MOI and parasite density, as the higher parasite counts increases the probability of having multiple infections. Conclusion Taken together our data revealed that α-thalassaemia may have a role in protection against certain parasite strains. The protection against the increase in MOI after the transmission season conferred by G6PD deficiency is probably due to clearance of

  7. Multiplicity of Plasmodium falciparum infection in asymptomatic children in Senegal: relation to transmission, age and erythrocyte variants.

    Science.gov (United States)

    Vafa, Manijeh; Troye-Blomberg, Marita; Anchang, Judith; Garcia, André; Migot-Nabias, Florence

    2008-01-23

    Individuals living in malaria endemic areas generally harbour multiple parasite strains. Multiplicity of infection (MOI) can be an indicator of immune status. However, whether this is good or bad for the development of immunity to malaria, is still a matter of debate. This study aimed to examine the MOI in asymptomatic children between two and ten years of age and to relate it to erythrocyte variants, clinical attacks, transmission levels and other parasitological indexes. Study took place in Niakhar area in Senegal, where malaria is mesoendemic and seasonal. Three hundred and seventy two asymptomatic children were included. Sickle-cell trait, G6PD deficiency (A- and Santamaria) and alpha+-thalassaemia (-alpha3.7 type) were determined using PCR. Multiplicity of Plasmodium falciparum infection, i.e. number of concurrent clones, was defined by PCR-based genotyping of the merozoite surface protein-2 (msp2), before and at the end of the malaria transmission season. The chi2-test, ANOVA, multivariate linear regression and logistic regression statistical tests were used for data analysis. MOI was significantly higher at the end of transmission season. The majority of PCR positive subjects had multiple infections at both time points (64% before and 87% after the transmission season). MOI did not increase in alpha-thalassaemic and G6PD mutated children. The ABO system and HbAS did not affect MOI at any time points. No association between MOI and clinical attack was observed. MOI did not vary over age at any time points. There was a significant correlation between MOI and parasite density, as the higher parasite counts increases the probability of having multiple infections. Taken together our data revealed that alpha-thalassaemia may have a role in protection against certain parasite strains. The protection against the increase in MOI after the transmission season conferred by G6PD deficiency is probably due to clearance of the malaria parasite at early stages of infection

  8. Plasmodium falciparum malaria

    African Journals Online (AJOL)

    Therapeutic efficacy of sulfadoxine-pyrimethamine for. Plasmodium falciparum malaria. A study 5 years after implementation of combination therapy in Mpumalanga,. South Africa. Aaron Mabuza, John Govere, Kobus .... Parasitological success was defined as conversion from a positive smear at recruitment to a negative ...

  9. Differences in gene transcriptomic pattern of Plasmodium falciparum in children with cerebral malaria and asymptomatic carriers

    DEFF Research Database (Denmark)

    Almelli, Talleh; Nuel, Grégory; Bischoff, Emmanuel

    2014-01-01

    , transcriptional factor proteins, proteins implicated in protein transport, as well as Plasmodium conserved and hypothetical proteins. Interestingly, UPs A1, A2, A3 and UPs B1 of var genes were predominantly found in cerebral malaria-associated isolates and those containing architectural domains of DC4, DC5, DC13...

  10. Asymptomatic Plasmodium spp. infection in Tierralta, Colombia.

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    Cucunubá, Zulma Milena; Guerra, Angela Patricia; Rahirant, Sonia Judith; Rivera, Jorge Alonso; Cortés, Liliana Jazmín; Nicholls, Rubén Santiago

    2008-11-01

    With the aim of determining the prevalence of asymptomatic Plasmodium spp. infection by thick smear and PCR and its association with demographic and epidemiological characteristics in the village of Nuevo Tay, Tierralta, Córdoba, Colombia, a cross-sectional population study was carried out, using random probabilistic sampling. Venous blood samples were taken from 212 people on day 0 for thick smear and PCR. Clinical follow-up and thick smears were carried out on days 14 and 28. The prevalence of Plasmodium spp. infection was 17.9% (38/212; 95% CI: 12.5-23.3%) and the prevalence of asymptomatic Plasmodiumspp. infection was 14.6% (31/212; 95% CI: 9.6-19.6%). Plasmodium vivax was found more frequently (20/31; 64.5%) than Plasmodium falciparum (9/31; 29%) and mixed infections (2/31; 6.5%). A significantly higher prevalence of asymptomatic infection was found in men (19.30%) than in women (9.18%) (prevalence ratio: 2.10; 95% CI: 1.01-4.34%; p = 0.02). People who developed symptoms had a significantly higher parasitemia on day 0 than those who remained asymptomatic, of 1,881.5 +/- 3,759 versus 79 +/- 106.9 (p = 0.008). PCR detected 50% more infections than the thick smears. The presence of asymptomatic Plasmodium spp. infection highlights the importance of carrying out active searches amongst asymptomatic populations residing in endemic areas.

  11. Plasmodium falciparum: sickle-cell trait is associated with higher prevalence of multiple infections in Gabonese children with asymptomatic infections.

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    Ntoumi, F; Mercereau-Puijalon, O; Ossari, S; Luty, A; Reltien, J; Georges, A; Millet, P

    1997-09-01

    Through PCR amplifications of the gene encoding the merozoite surface antigen 2, utilizing allele-specific 3D7 and FC27 probes, we have examined the prevalence of Plasmodium falciparum in children aged from 7 to 14 years living in a village located in the equatorial forest region of Central Africa (Gabon). Using this technique, 61% (100/163) of the blood samples were shown to be infected with P. falciparum with 24 alleles distinguished by size polymorphism and sequence type. The two main families (3D7 and FC27) and hybrid alleles were detected regardless of sex and hemoglobin phenotype. No age-related changes in prevalence of P. falciparum strains were observed; however, the prevalence of infection (42%) was significantly lower in individuals with the sickle-cell trait compared with their normal-hemoglobin counterparts (68%). Mixtures of genetically distinct parasite clones were present in 82% of children carrying the sickle-cell trait but in only 58% of normal-hemoglobin carriers. The significance of these observations regarding the design and interpretation of epidemiological investigations is discussed in the context of malaria transmission in the region studied.

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

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    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

    2015-05-01

    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. 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). 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. 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 outbreaks due to travel to nearby islands

  13. PLASMODIUM MALARIAE INFECTION BOOSTS PLASMODIUM FALCIPARUM GAMETOCYTE PRODUCTION

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    MCKENZIE, F. ELLIS; JEFFERY, GEOFFREY M.; COLLINS, WILLIAM E.

    2008-01-01

    We analyzed records of malariotherapy patients sequentially or simultaneously inoculated with Plasmodium falciparum and Plasmodium malariae. Gametocyte production was enhanced in P. falciparum by prior or concurrent P. malariae infection but diminished or unaffected in P. malariae by P. falciparum. Conversely, asexual-form production was diminished in P. malariae but unaffected in P. falciparum. PMID:12452496

  14. Community screening and treatment of asymptomatic carriers of Plasmodium falciparum with artemether-lumefantrine to reduce malaria disease burden: a modelling and simulation analysis

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    Ubben David

    2011-07-01

    Full Text Available Abstract Background Asymptomatic carriers of Plasmodium falciparum serve as a reservoir of parasites for malaria transmission. Identification and treatment of asymptomatic carriers within a region may reduce the parasite reservoir and influence malaria transmission in that area. Methods Using computer simulation, this analysis explored the impact of community screening campaigns (CSC followed by systematic treatment of P. falciparum asymptomatic carriers (AC with artemether-lumefantrine (AL on disease transmission. The model created by Okell et al (originally designed to explore the impact of the introduction of treatment with artemisinin-based combination therapy on malaria endemicity was modified to represent CSC and treatment of AC with AL, with the addition of malaria vector seasonality. The age grouping, relative distribution of age in a region, and degree of heterogeneity in disease transmission were maintained. The number and frequency of CSC and their relative timing were explored in terms of their effect on malaria incidence. A sensitivity analysis was conducted to determine the factors with the greatest impact on the model predictions. Results The simulation showed that the intervention that had the largest effect was performed in an area with high endemicity (entomological inoculation rate, EIR > 200; however, the rate of infection returned to its normal level in the subsequent year, unless the intervention was repeated. In areas with low disease burden (EIR Conclusions Community screening and treatment of asymptomatic carriers with AL may reduce malaria transmission significantly. The initial level of disease intensity has the greatest impact on the potential magnitude and duration of malaria reduction. When combined with other interventions (e.g. long-lasting insecticide-treated nets, rapid diagnostic tests, prompt diagnosis and treatment, and, where appropriate, indoor residual spraying the effect of this intervention can be

  15. Comparison of PCR and microscopy for the detection of asymptomatic malaria in a Plasmodium falciparum/vivax endemic area in Thailand

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    Miller Robert

    2006-12-01

    Full Text Available Abstract Objective The main objective of this study was to compare the performance of nested PCR with expert microscopy as a means of detecting Plasmodium parasites during active malaria surveillance in western Thailand. Methods The study was performed from May 2000 to April 2002 in the village of Kong Mong Tha, located in western Thailand. Plasmodium vivax (PV and Plasmodium falciparum (PF are the predominant parasite species in this village, followed by Plasmodium malariae (PM and Plasmodium ovale (PO. Each month, fingerprick blood samples were taken from each participating individual and used to prepare thick and thin blood films and for PCR analysis. Results PCR was sensitive (96% and specific (98% for malaria at parasite densities ≥ 500/μl; however, only 18% (47/269 of P. falciparum- and 5% (20/390 of P. vivax-positive films had parasite densities this high. Performance of PCR decreased markedly at parasite densities P. falciparum and 24% for P. vivax at densities Conclusion Although PCR performance appeared poor when compared to microscopy, data indicated that the discrepancy between the two methods resulted from poor performance of microscopy at low parasite densities rather than poor performance of PCR. These data are not unusual when the diagnostic method being evaluated is more sensitive than the reference method. PCR appears to be a useful method for detecting Plasmodium parasites during active malaria surveillance in Thailand.

  16. Antibodies and Plasmodium falciparum merozoites

    NARCIS (Netherlands)

    Ramasamy, R; Ramasamy, M; Yasawardena, S

    There is considerable interest in using merozoite proteins in a vaccine against falciparum malaria. Observations that antibodies to merozoite surface proteins block invasion are a basis for optimism. This article draws attention to important and varied aspects of how antibodies to Plasmodium

  17. Studies On the Incidence of Asymptomatic Plasmodium Infection ...

    African Journals Online (AJOL)

    The incidence of asymptomatic Plasmodium falciparum infection among orphans between age groups, gender and blood groups was investigated. Standard microscopic methods were used to screen for malaria parasites in the blood specimens obtained from eighty-five (85) subjects in three orphanages in Kaduna and ...

  18. Chemical genetics of Plasmodium falciparum

    Science.gov (United States)

    Guiguemde, W. Armand; Shelat, Anang A.; Bouck, David; Duffy, Sandra; Crowther, Gregory J.; Davis, Paul H.; Smithson, David C.; Connelly, Michele; Clark, Julie; Zhu, Fangyi; Jiménez-Díaz, María B; Martinez, María S; Wilson, Emily B.; Tripathi, Abhai K.; Gut, Jiri; Sharlow, Elizabeth R.; Bathurst, Ian; El Mazouni, Farah; Fowble, Joseph W; Forquer, Isaac; McGinley, Paula L; Castro, Steve; Angulo-Barturen, Iñigo; Ferrer, Santiago; Rosenthal, Philip J.; DeRisi, Joseph L; Sullivan, David J.; Lazo, John S.; Roos, David S.; Riscoe, Michael K.; Phillips, Margaret A.; Rathod, Pradipsinh K.; Van Voorhis, Wesley C.; Avery, Vicky M; Guy, R. Kiplin

    2010-01-01

    Malaria caused by Plasmodium falciparum is a catastrophic disease worldwide (880,000 deaths yearly). Vaccine development has proved difficult and resistance has emerged for most antimalarials. In order to discover new antimalarial chemotypes, we have employed a phenotypic forward chemical genetic approach to assay 309,474 chemicals. Here we disclose structures and biological activity of the entire library, many of which exhibited potent in vitro activity against drug resistant strains, and detailed profiling of 172 representative candidates. A reverse chemical genetic study identified 19 new inhibitors of 4 validated drug targets and 15 novel binders among 61 malarial proteins. Phylochemogenetic profiling in multiple organisms revealed similarities between Toxoplasma gondii and mammalian cell lines and dissimilarities between P. falciparum and related protozoans. One exemplar compound displayed efficacy in a murine model. Overall, our findings provide the scientific community with new starting points for malaria drug discovery. PMID:20485428

  19. A case report of Plasmodium vivax , Plasmodium falciparum and ...

    African Journals Online (AJOL)

    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 ...

  20. Dynamics of malaria transmission and susceptibility to clinical malaria episodes following treatment of Plasmodium falciparum asymptomatic carriers: results of a cluster-randomized study of community-wide screening and treatment, and a parallel entomology study.

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    Tiono, Alfred B; Guelbeogo, Moussa W; Sagnon, N Falé; Nébié, Issa; Sirima, Sodiomon B; Mukhopadhyay, Amitava; Hamed, Kamal

    2013-11-12

    In malaria-endemic countries, large proportions of individuals infected with Plasmodium falciparum are asymptomatic and constitute a reservoir of parasites for infection of newly hatched mosquitoes. Two studies were run in parallel in Burkina Faso to evaluate the impact of systematic identification and treatment of asymptomatic carriers of P. falciparum, detected by rapid diagnostic test, on disease transmission and susceptibility to clinical malaria episodes. A clinical study assessed the incidence of symptomatic malaria episodes with a parasite density >5,000/μL after three screening and treatment campaigns ~1 month apart before the rainy season; and an entomological study determined the effect of these campaigns on malaria transmission as measured by entomological inoculation rate. The intervention arm had lower prevalence of asymptomatic carriers of asexual parasites and lower prevalence of gametocyte carriers during campaigns 2 and 3 as compared to the control arm. During the entire follow-up period, out of 13,767 at-risk subjects, 2,516 subjects (intervention arm 1,332; control arm 1,184) had symptomatic malaria. Kaplan-Meier analysis of the incidence of first symptomatic malaria episode with a parasite density >5,000/μL showed that, in the total population, the two treatment arms were similar until Week 11-12 after campaign 3, corresponding with the beginning of the malaria transmission season, after which the probability of being free of symptomatic malaria was lower in the intervention arm (logrank p entomological inoculation rate was comparable in both arms, with September peaks in both indices. Community screening and targeted treatment of asymptomatic carriers of P. falciparum had no effect on the dynamics of malaria transmission, but seemed to be associated with an increase in the treated community's susceptibility to symptomatic malaria episodes after the screening campaigns had finished. These results highlight the importance of further

  1. Anti- Plasmodium Falciparum Activity of Extracts from ...

    African Journals Online (AJOL)

    malaria drugs. Dendrathema indicum/ Dunkufea plant used in the treatment of malaria in the northern part of Nigeria was evaluated for activity against Plasmodium falciparum. The crude ethanol extract of the plant, n-hexane, chloroform and ethyl ...

  2. Sickle cell trait protects against Plasmodium falciparum infection.

    Science.gov (United States)

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

    2012-10-01

    Although sickle cell trait protects against severe disease due to Plasmodium falciparum, it has not been clear whether sickle trait also protects against asymptomatic infection (parasitemia). To address this question, the authors identified 171 persistently smear-negative children and 450 asymptomatic persistently smear-positive children in Bancoumana, Mali (June 1996 to June 1998). They then followed both groups for 2 years using a cohort-based strategy. Among the 171 children with persistently negative smears, the median time for conversion to smear-positive was longer for children with sickle trait than for children without (274 vs. 108 days, P sickle trait than for children without (190 vs. 365 days; P = 0.02). These protective effects of sickle trait against asymptomatic P. falciparum infection under conditions of natural transmission were demonstrable using a cohort-based approach but not when the same data were examined using a cross-sectional approach.

  3. Efficacy of Artemether in Unresolving Plasmodium Falciparum Malaria

    African Journals Online (AJOL)

    The emergence of possible resistant Plasmodium falciparum malaria to artemisinin known for its immense benefit in malaria chemotherapy is worrisome. We report a case of unresolving Plasmodium falciparum malaria to Artesunate treatment in a 29- year old man in Enugu Nigeria. Plasmodium falciparum count of Giemsa ...

  4. Interleukin-10 regulates hepcidin in Plasmodium falciparum malaria

    KAUST Repository

    Huang, Honglei

    2014-02-10

    Background: Acute malarial anemia remains a major public health problem. Hepcidin, the major hormone controlling the availability of iron, is raised during acute and asymptomatic parasitemia. Understanding the role and mechanism of raised hepcidin and so reduced iron availability during infection is critical to establish evidence-based guidelines for management of malaria anemia. Our recent clinical evidence suggests a potential role of IL-10 in the regulation of hepcidin in patients with acute P. falciparum malaria. Methods: We have measured secretion of hepcidin by primary macrophages and the hepatoma cell line HepG2 stimulated with IL-10, IL-6 and Plasmodium falciparum-infected erythrocytes. Findings: We have observed that IL-10 and IL-6 production increased in primary macrophages when these cells were co-cultured with Plasmodium falciparum-infected erythrocytes. We found that IL-10 induced hepcidin secretion in primary macrophages in a dose-dependent manner but not in HepG2 cells. These effects were mediated through signal transducer and activator of transcription (STAT) 3-phosphorylation and completely abrogated by a specific STAT3 inhibitor. Conclusion: IL-10 can directly regulate hepcidin in primary macrophages but not in HepG2 cells. This effect can be modulated by Plasmodium falciparum. The results are consistent with a role for IL-10 in modulating iron metabolism during acute phase of infection. 2014 Huang et al.

  5. Infectivity of Plasmodium falciparum gametocytes in patients ...

    African Journals Online (AJOL)

    The difficulty of identifying gametocyte carriers from the community is often limited due to financial and human resources constraints. The available alternative ... Plasmodium falciparum was the predominant parasite species and P. malariae being the only minor species, accounting for 0.9% of malaria cases. Clinical malaria ...

  6. Resistance patterns of plasmodium falciparum malaria to ...

    African Journals Online (AJOL)

    Resistance patterns of plasmodium falciparum malaria to chloroquine in Kampala, Uganda. ... Sixty three (65.6%) patients showed clinical improvement, 29 (30.2%) deteriorated and four (4.2%) had no change. Adequate parasitogical response was seen in 71 (74 %), moderate in four (4.2%) and poor in 21 (21.8%) patients.

  7. Plasmodium falciparum malaria, southern Algeria, 2007.

    Science.gov (United States)

    Boubidi, Said C; Gassen, Ibrahim; Khechache, Yacine; Lamali, Karima; Tchicha, Boualem; Brengues, Cecile; Menegon, Michela; Severini, Carlo; Fontenille, Didier; Harrat, Zoubir

    2010-02-01

    An outbreak of Plasmodium falciparum malaria occurred in Tinzaouatine in southern Algeria in 2007. The likely vector, Anopheles gambiae mosquitoes, had not been detected in Algeria. Genes for resistance to chloroquine were detected in the parasite. The outbreak shows the potential for an increase in malaria vectors in Algeria.

  8. Plasmodium falciparum Malaria, Southern Algeria, 2007

    Science.gov (United States)

    Gassen, Ibrahim; Khechache, Yacine; Lamali, Karima; Tchicha, Boualem; Brengues, Cécile; Menegon, Michela; Severini, Carlo; Fontenille, Didier; Harrat, Zoubir

    2010-01-01

    An outbreak of Plasmodium falciparum malaria occurred in Tinzaouatine in southern Algeria in 2007. The likely vector, Anopheles gambiae mosquitoes, had not been detected in Algeria. Genes for resistance to chloroquine were detected in the parasite. The outbreak shows the potential for an increase in malaria vectors in Algeria. PMID:20113565

  9. Plasmodium falciparum Malaria, Southern Algeria, 2007

    OpenAIRE

    Boubidi, Sa?d C; Gassen, Ibrahim; Khechache, Yacine; Lamali, Karima; Tchicha, Boualem; Brengues, C?cile; Menegon, Michela; Severini, Carlo; Fontenille, Didier; Harrat, Zoubir

    2010-01-01

    An outbreak of Plasmodium falciparum malaria occurred in Tinzaouatine in southern Algeria in 2007. The likely vector, Anopheles gambiae mosquitoes, had not been detected in Algeria. Genes for resistance to chloroquine were detected in the parasite. The outbreak shows the potential for an increase in malaria vectors in Algeria.

  10. Prevalence of Plasmodium falciparum malaria among patients ...

    African Journals Online (AJOL)

    This study reports malaria infection caused by the parasite Plasmodium falciparum in University of Ilorin Teaching Hospital (UITH), Ilorin, Kwara State, Nigeria. This study provides information on the infectivity rate of this parasite in dry season and the variation of laboratory diagnosed cases of malaria to clinically diagnosed ...

  11. Plasmodium falciparum malaria and antimalarial interventions in ...

    African Journals Online (AJOL)

    Plasmodium falciparum malaria is one of the most important parasitic diseases affecting sub-Saharan Africa, despite the availability of interventions. It exerts tremendous socio-economic and medical burden on the continent, particularly in under five children and pregnant women. In this review, we have attempted to ...

  12. In vitro susceptibility of Plasmodium falciparum to ...

    African Journals Online (AJOL)

    Background: Malaria is the primary cause of hospitalization in Côte d'Ivoire. Early treatment is one of the strategies to control this illness. However, the spread of resistance of Plasmodium falciparum to antimalarial drugs can seriously compromise this strategy. Objectives: The aim of this study was to assess the in vitro ...

  13. Relationship between Onchocerciasis and Plasmodium falciparum ...

    African Journals Online (AJOL)

    Objective: To determine if there is a causal relationship between Plasmodium falciparum and clinical filariasis in individuals exposed to both infections. Methods: An onchocerciasis endemic community in Imo State, South East Nigeria was screened and persons showing overt clinical signs of onchocerciasis were selected ...

  14. Population genomics diversity of Plasmodium falciparum in malaria ...

    African Journals Online (AJOL)

    There is however little information about the genetic diversity of Plasmodium falciparum in Nigeria. Objective: To determine the population genomic diversity of Plasmodium falciparum in malaria patients attending Okelele Com- munity Healthcare Centre, Okelele, Ilorin, Kwara State. Methods: In this study, 50 Plasmodium ...

  15. Molecular monitoring of Plasmodium falciparum resistance to artemisinin in Tanzania

    Directory of Open Access Journals (Sweden)

    Genton Blaise

    2006-12-01

    Full Text Available Abstract Artemisinin-based combination therapies (ACTs are recommended for use against uncomplicated malaria in areas of multi-drug resistant malaria, such as sub-Saharan Africa. However, their long-term usefulness in these high transmission areas remains unclear. It has been suggested that documentation of the S769N PfATPase6 mutations may indicate an emergence of artemisinin resistance of Plasmodium falciparum in the field. The present study assessed PfATPase6 mutations (S769N and A623E in 615 asymptomatic P. falciparum infections in Tanzania but no mutant genotype was detected. This observation suggests that resistance to artemisinin has not yet been selected in Tanzania, supporting the Ministry of Health's decision to adopt artemether+lumefantrine as first-line malaria treatment. The findings recommend further studies to assess PfATPase6 mutations in sentinel sites and verify their usefulness in monitoring emergency of ACT resistance.

  16. Single low dose primaquine to reduce gametocyte carriage and Plasmodium falciparum transmission after artemether-lumefantrine in children with asymptomatic infection: a randomised, double-blind, placebo-controlled trial

    NARCIS (Netherlands)

    Goncalves, B.P.; Tiono, A.B.; Ouedraogo, A.; Guelbeogo, W.M.; Bradley, J.; Nebie, I.; Siaka, D.; Lanke, K.H.; Eziefula, A.C.; Diarra, A.; Pett, H.E.; Bougouma, E.C.; Sirima, S.B.; Drakeley, C.; Bousema, T.

    2016-01-01

    BACKGROUND: A single low dose (0.25 mg/kg) of primaquine is recommended as a gametocytocide in combination with artemisinin-based combination therapies for Plasmodium falciparum but its effect on post-treatment gametocyte circulation and infectiousness to mosquitoes has not been quantified. METHODS:

  17. Gametocytogenesis : the puberty of Plasmodium falciparum

    Directory of Open Access Journals (Sweden)

    Ariey Frédéric

    2004-07-01

    Full Text Available Abstract The protozoan Plasmodium falciparum has a complex life cycle in which asexual multiplication in the vertebrate host alternates with an obligate sexual reproduction in the anopheline mosquito. Apart from the apparent recombination advantages conferred by sex, P. falciparum has evolved a remarkable biology and adaptive phenotypes to insure its transmission despite the dangers of sex. This review mainly focuses on the current knowledge on commitment to sexual development, gametocytogenesis and the evolutionary significance of various aspects of gametocyte biology. It goes further than pure biology to look at the strategies used to improve successful transmission. Although gametocytes are inevitable stages for transmission and provide a potential target to fight malaria, they have received less attention than the pathogenic asexual stages. There is a need for research on gametocytes, which are a fascinating stage, responsible to a large extent for the success of P. falciparum.

  18. Premunition in Plasmodium falciparum malaria

    African Journals Online (AJOL)

    STORAGESEVER

    2010-03-08

    Mar 8, 2010 ... Malarial paroxysms become less severe and irregular in periodicity as the host develops immunity. This immu- nity, however, is not a sterilizing type in that the infection persists longer than the symptoms and individuals can exhibit relapses or recrudescences or become reinfected. If untreated, P. falciparum ...

  19. Characterizing Antibody Responses to Plasmodium vivax and Plasmodium falciparum Antigens in India Using Genome-Scale Protein Microarrays.

    Directory of Open Access Journals (Sweden)

    Swapna Uplekar

    2017-01-01

    Full Text Available Understanding naturally acquired immune responses to Plasmodium in India is key to improving malaria surveillance and diagnostic tools. Here we describe serological profiling of immune responses at three sites in India by probing protein microarrays consisting of 515 Plasmodium vivax and 500 Plasmodium falciparum proteins with 353 plasma samples. A total of 236 malaria-positive (symptomatic and asymptomatic plasma samples and 117 malaria-negative samples were collected at three field sites in Raurkela, Nadiad, and Chennai. Indian samples showed significant seroreactivity to 265 P. vivax and 373 P. falciparum antigens, but overall seroreactivity to P. vivax antigens was lower compared to P. falciparum antigens. We identified the most immunogenic antigens of both Plasmodium species that were recognized at all three sites in India, as well as P. falciparum antigens that were associated with asymptomatic malaria. This is the first genome-scale analysis of serological responses to the two major species of malaria parasite in India. The range of immune responses characterized in different endemic settings argues for targeted surveillance approaches tailored to the diverse epidemiology of malaria across the world.

  20. Population genomics diversity of Plasmodium falciparum in malaria ...

    African Journals Online (AJOL)

    Abstract. Background: Plasmodium falciparum, the most dangerous malaria parasite species to humans remains an important public health concern in Okelele, a rural community in Ilorin, Kwara State, Nigeria. There is however little information about the genetic diversity of Plasmodium falciparum in Nigeria. Objective: To ...

  1. In-virto sensitivity of plasmodium falciparum to chloroquine ...

    African Journals Online (AJOL)

    Objective: To determine how sensitive Plasmodium falciparum is to the major antimalarial drugs in Madagascar. Design: Assessment of Plasmodium falciparum isolates sensitivity to antimalarials, by use of the in-vitro radioisotope method. Setting: Ankazobe and Saharevo in the foothill areas; and Toamasina and Tolagnaro ...

  2. Artemisinin resistance marker of Plasmodium falciparum in Osogbo ...

    African Journals Online (AJOL)

    Artemisinin derivatives constitute a key component of the present-day treatment for Plasmodium falciparum malaria. Resistance with artemisinins is generally associated with S769N point mutation in the sarco-endoplasmic reticulumdependant ATPase6 (SERCA ATPase6) gene of Plasmodium falciparum, few studies have ...

  3. Population genomics diversity of Plasmodium falciparum in malaria ...

    African Journals Online (AJOL)

    Background: Plasmodium falciparum, the most dangerous malaria parasite species to humans remains an important public health concern in Okelele, a rural community in Ilorin, Kwara State, Nigeria. There is however little information about the genetic diversity of Plasmodium falciparum in Nigeria. Objective: To determine ...

  4. The persistence and oscillations of submicroscopic Plasmodium falciparum and Plasmodium vivax infections over time in Vietnam: an open cohort study.

    Science.gov (United States)

    Nguyen, Thuy-Nhien; von Seidlein, Lorenz; Nguyen, Tuong-Vy; Truong, Phuc-Nhi; Hung, Son Do; Pham, Huong-Thu; Nguyen, Tam-Uyen; Le, Thanh Dong; Dao, Van Hue; Mukaka, Mavuto; Day, Nicholas Pj; White, Nicholas J; Dondorp, Arjen M; Thwaites, Guy E; Hien, Tran Tinh

    2018-02-01

    A substantial proportion of Plasmodium species infections are asymptomatic with densities too low to be detectable with standard diagnostic techniques. The importance of such asymptomatic plasmodium infections in malaria transmission is probably related to their duration and density. To explore the duration of asymptomatic plasmodium infections and changes in parasite densities over time, a cohort of participants who were infected with Plasmodium parasites was observed over a 2-year follow-up period. In this open cohort study, inhabitants of four villages in Vietnam were invited to participate in baseline and subsequent 3-monthly surveys up to 24 months, which included the collection of venous blood samples. Samples were batch-screened using ultra-sensitive (u)PCR (lower limit of detection of 22 parasites per mL). Participants found to be infected by uPCR during any of these surveys were invited to join a prospective cohort and provide monthly blood samples. We estimated the persistence of Plasmodium falciparum and Plasmodium vivax infections and changes in parasite densities over a study period of 24 months. Between Dec 1, 2013, and Jan 8, 2016, 356 villagers participated in between one and 22 surveys. These study participants underwent 4248 uPCR evaluations (11·9 tests per participant). 1874 (32%) of 4248 uPCR tests indicated a plasmodium infection; 679 (36%) of 1874 tests were P falciparum monoinfections, 507 (27%) were P vivax monoinfections, 463 (25%) were co-infections with P falciparum and P vivax, and 225 (12%) were indeterminate species of Plasmodium. The median duration of P falciparum infection was 2 months (IQR 1-3); after accounting for censoring, participants had a 20% chance of having parasitaemia for 4 months or longer. The median duration of P vivax infection was 6 months (3-9), and participants had a 59% chance of having parasitaemia for 4 months or longer. The parasite densities of persistent infections oscillated; following ultralow

  5. Cytokine balance in human malaria: does Plasmodium vivax elicit more inflammatory responses than Plasmodium falciparum?

    Directory of Open Access Journals (Sweden)

    Raquel M Gonçalves

    Full Text Available BACKGROUND: The mechanisms by which humans regulate pro- and anti-inflammatory responses on exposure to different malaria parasites remains unclear. Although Plasmodium vivax usually causes a relatively benign disease, this parasite has been suggested to elicit more host inflammation per parasitized red blood cell than P. falciparum. METHODOLOGY/PRINCIPAL FINDINGS: We measured plasma concentrations of seven cytokines and two soluble tumor necrosis factor (TNF-α receptors, and evaluated clinical and laboratory outcomes, in Brazilians with acute uncomplicated infections with P. vivax (n = 85, P. falciparum (n = 30, or both species (n = 12, and in 45 asymptomatic carriers of low-density P. vivax infection. Symptomatic vivax malaria patients, compared to those infected with P. falciparum or both species, had more intense paroxysms, but they had no clear association with a pro-inflammatory imbalance. To the contrary, these patients had higher levels of the regulatory cytokine interleukin (IL-10, which correlated positively with parasite density, and elevated IL-10/TNF-α, IL-10/interferon (IFN-γ, IL-10/IL-6 and sTNFRII/TNF-α ratios, compared to falciparum or mixed-species malaria patient groups. Vivax malaria patients had the highest levels of circulating soluble TNF-α receptor sTNFRII. Levels of regulatory cytokines returned to normal values 28 days after P. vivax clearance following chemotherapy. Finally, asymptomatic carriers of low P. vivax parasitemias had substantially lower levels of both inflammatory and regulatory cytokines than did patients with clinical malaria due to either species. CONCLUSIONS: Controlling fast-multiplying P. falciparum blood stages requires a strong inflammatory response to prevent fulminant infections, while reducing inflammation-related tissue damage with early regulatory cytokine responses may be a more cost-effective strategy in infections with the less virulent P. vivax parasite. The early induction

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

    DEFF Research Database (Denmark)

    Rottmann, Matthias; Lavstsen, Thomas; Mugasa, Joseph Paschal

    2006-01-01

    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...... 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...

  7. Peripheral blood cell signatures of Plasmodium falciparum infection during pregnancy

    DEFF Research Database (Denmark)

    Ibitokou, Samad; Oesterholt, Mayke; Brutus, Laurent

    2012-01-01

    Sequestration of Plasmodium falciparum-infected erythrocytes in placental intervillous spaces causes inflammation and pathology. Knowledge of the profiles of immune cells associated with the physiopathology of pregnancy-associated malaria (PAM) is scarce. We conducted a longitudinal, prospective...

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

    DEFF Research Database (Denmark)

    Hempel, Casper

    2017-01-01

    Plasmodium falciparum invades erythrocytes as an essential part of their life cycle. While living inside erythrocytes, the parasite remodels the cell's intracellular organization as well as its outer surface. Late trophozoite-stage parasites and schizonts introduce numerous small protrusions...

  9. Asymptomatic Plasmodium infections in 18 villages of southern Savannakhet Province, Lao PDR (Laos).

    Science.gov (United States)

    Phommasone, Koukeo; Adhikari, Bipin; Henriques, Gisela; Pongvongsa, Tiengkham; Phongmany, Panom; von Seidlein, Lorenz; White, Nicholas J; Day, Nicholas P J; M Dondorp, Arjen; Newton, Paul N; Imwong, Mallika; Mayxay, Mayfong

    2016-05-27

    A large fraction of Plasmodium infections do not cause clinical signs and symptoms of disease and persist at densities in blood that are not detectable by microscopy or rapid diagnostic tests. These infections may be critical as a transmission reservoir in areas of low malaria endemicity. Understanding the epidemiology of these infections would be helpful for malaria elimination. A cross-sectional survey was conducted in Thapangthong and Nong Districts of Savannakhet Province, Lao PDR, to determine the prevalence of parasitaemia. A total of 888 blood samples were collected from afebrile volunteers aged ≥15 years in 18 villages during March and July 2015. Plasmodium infections were diagnosed by rapid diagnostic tests (RDT) and high volume, ultra-sensitive quantitative polymerase chain reaction (uPCR). uPCR detected Plasmodium infections in 175 of 888 samples (20 %). The species distribution was Plasmodium falciparum 3.6 % (32/888), Plasmodium vivax 11.1 % (99/888), mixed infections with P. falciparum and P. vivax 1.6 % (14/888) and Plasmodium of undetermined species 3.4 % (30/888). RDT identified only 2 % (18/888) positive cases. Using uPCR as reference, the sensitivity and specificity of RDTs were 28 and 100 %, respectively, in detecting P. falciparum infections, and 3 and 99 % in detecting asymptomatic P. vivax infections. The K13 kelch propeller domain C580Y mutation, associated with reduced susceptibility to artemisinin derivatives, was found in 75 % (12/18) of P. falciparum isolates from Thapangthong and in 7 % (2/28) from Nong (p Laos and could reverse the gains achieved by the successful control of malaria in Laos and the Greater Mekong Sub-region (GMS). Rapid elimination of P. falciparum has to be a top priority in Laos as well as in the wider GMS.

  10. Susceptibility of Plasmodium falciparum to the drugs used to treat ...

    African Journals Online (AJOL)

    Objectives. To monitor the sensitivity of Plasmodium falciparum to the drugs used to treat severe malaria and to prevent malaria in Comoros and Madagascar. Design. We used the in vitro isotopic method to test the sensitivity of P. falciparum to quinine, mefloquine and cycloguanil. Results. We tested fresh isolates of P.

  11. The periodicity of Plasmodium vivax and Plasmodium falciparum in Venezuela.

    Science.gov (United States)

    Grillet, María-Eugenia; El Souki, Mayida; Laguna, Francisco; León, José Rafael

    2014-01-01

    We investigated the periodicity of Plasmodium vivax and P. falciparum incidence in time-series of malaria data (1990-2010) from three endemic regions in Venezuela. In particular, we determined whether disease epidemics were related to local climate variability and regional climate anomalies such as the El Niño Southern Oscillation (ENSO). Malaria periodicity was found to exhibit unique features in each studied region. Significant multi-annual cycles of 2- to about 6-year periods were identified. The inter-annual variability of malaria cases was coherent with that of SSTs (ENSO), mainly at temporal scales within the 3-6 year periods. Additionally, malaria cases were intensified approximately 1 year after an El Niño event, a pattern that highlights the role of climate inter-annual variability in the epidemic patterns. Rainfall mediated the effect of ENSO on malaria locally. Particularly, rains from the last phase of the season had a critical role in the temporal dynamics of Plasmodium. The malaria-climate relationship was complex and transient, varying in strength with the region and species. By identifying temporal cycles of malaria we have made a first step in predicting high-risk years in Venezuela. Our findings emphasize the importance of analyzing high-resolution spatial-temporal data to better understand malaria transmission dynamics. Copyright © 2013 Elsevier B.V. All rights reserved.

  12. Plasmodium falciparum erythrocyte invasion: combining function with immune evasion.

    Directory of Open Access Journals (Sweden)

    Gavin J Wright

    2014-03-01

    Full Text Available All the symptoms and pathology of malaria are caused by the intraerythrocytic stages of the Plasmodium parasite life cycle. Because Plasmodium parasites cannot replicate outside a host cell, their ability to recognize and invade erythrocytes is an essential step for both parasite survival and malaria pathogenesis. This makes invasion a conceptually attractive vaccine target, especially because it is one of the few stages when the parasite is directly exposed to the host humoral immune system. This apparent vulnerability, however, has been countered by the parasite, which has evolved sophisticated molecular mechanisms to evade the host immune response so that parasites asymptomatically replicate within immune individuals. These mechanisms include the expansion of parasite invasion ligands, resulting in multiple and apparently redundant invasion "pathways", highly polymorphic parasite surface proteins that are immunologically distinct, and parasite proteins which are poorly immunogenic. These formidable defences have so far thwarted attempts to develop an effective blood-stage vaccine, leading many to question whether there really is an exploitable chink in the parasite's immune evasion defences. Here, we review recent advances in the molecular understanding of the P. falciparum erythrocyte invasion field, discuss some of the challenges that have so far prevented the development of blood-stage vaccines, and conclude that the parasite invasion ligand RH5 represents an essential pinch point that might be vulnerable to vaccination.

  13. In vivo switching between variant surface antigens in human Plasmodium falciparum infection

    DEFF Research Database (Denmark)

    Staalsoe, Trine; Hamad, Amel A; Hviid, Lars

    2002-01-01

    A semi-immune individual was retrospectively found to have maintained an apparently monoclonal and genotypically stable asymptomatic infection for months after clinical cure of a Plasmodium falciparum malaria episode. Before the attack, the individual had no antibodies to variant surface antigens...

  14. Comparison of asymptomatic Plasmodium spp. infection in two malaria-endemic Colombian locations.

    Science.gov (United States)

    Cucunubá, Zulma Milena; Guerra, Ángela Patricia; Rivera, Jorge Alonso; Nicholls, Rubén Santiago

    2013-02-01

    Asymptomatic infection by Plasmodium spp. could help explain the dynamics of malaria transmission in low-transmission regions. We therefore compared the prevalence of asymptomatic infection by Plasmodium spp. in two Colombian locations, Tierralta and Tumaco, with different transmission patterns, different ecological and epidemiological characteristics and potentially different associated factors. Two cross-sectional studies were carried out between September 2006 and November 2007. Infection by Plasmodium spp. was determined using polymerase chain reaction (PCR) and microscopy. Prevalence of asymptomatic infection at day 0 in Tierralta was 11.3% (95% CI 7.2-16.8) by microscopy and 16.5% (95% CI 11.5-22.9) by PCR, while in Tumaco, values were 2.4% (95% CI 0.7-5.5) and 5.8% (95% CI 2.3-9.2) respectively. General prevalence of asymptomatic plasmodium infection after 28 days of follow-up was 5% (95% CI 3.2-7.7), 6.6% (95% CI 3.8-10.6%) in Tierralta and 3.4% (95% CI 1.5-6.6%) in Tumaco. Plasmodium vivax was predominant in Tierralta, P. falciparum in Tumaco. The main associated factors were male sex (aOR 2.5; 95% CI 1.0-6.7) and two to five previous malaria episodes (aOR 3.0; 95% CI 1.0-9.4). PCR detected 61% more infections than microscopy. Measurement of the prevalence of asymptomatic Plasmodium spp. infection is suggested as part of the epidemiologic evaluation of malaria in low-transmission areas such as Colombia.

  15. Plasmodium falciparum secretome in erythrocyte and beyond

    Directory of Open Access Journals (Sweden)

    Rani eSoni

    2016-02-01

    Full Text Available Plasmodium falciparum is the causative agent of deadly malaria disease. It is an intracellular eukaryote and completes its multi-stage life cycle spanning the two hosts viz, mosquito and human. In order to habituate within host environment, parasite conform several strategies to evade host immune responses such as surface antigen polymorphism or modulation of host immune system and it is mediated by secretion of proteins from parasite to the host erythrocyte and beyond, collectively known as, malaria secretome. In this review, we will discuss about the deployment of parasitic secretory protein in mechanism implicated for immune evasion, protein trafficking, providing virulence, changing permeability and cyto-adherence of infected erythrocyte. We will be covering the possibilities of developing malaria secretome as a drug/vaccine target. This gathered information will be worthwhile in depicting a well-organized picture for host-pathogen interplay during the malaria infection and may also provide some clues for development of novel anti-malarial therapies.

  16. Promoter regions of Plasmodium vivax are poorly or not recognized by Plasmodium falciparum

    Directory of Open Access Journals (Sweden)

    del Portillo Hernando A

    2007-02-01

    Full Text Available Abstract Background Heterologous promoter analysis in Plasmodium has revealed the existence of conserved cis regulatory elements as promoters from different species can drive expression of reporter genes in heterologous transfection assays. Here, the functional characterization of different Plasmodium vivax promoters in Plasmodium falciparum using luciferase as the reporter gene is presented. Methods Luciferase reporter plasmids harboring the upstream regions of the msp1, dhfr, and vir3 genes as well as the full-length intergenic regions of the vir23/24 and ef-1α genes of P. vivax were constructed and transiently transfected in P. falciparum. Results Only the constructs with the full-length intergenic regions of the vir23/24 and ef-1α genes were recognized by the P. falciparum transcription machinery albeit to values approximately two orders of magnitude lower than those reported by luc plasmids harbouring promoter regions from P. falciparum and Plasmodium berghei. A bioinformatics approach allowed the identification of a motif (GCATAT in the ef-1α intergenic region that is conserved in five Plasmodium species but is degenerate (GCANAN in P. vivax. Mutations of this motif in the P. berghei ef-1α promoter region decreased reporter expression indicating it is active in gene expression in Plasmodium. Conclusion Together, this data indicates that promoter regions of P. vivax are poorly or not recognized by the P. falciparum transcription machinery suggesting the existence of P. vivax-specific transcription regulatory elements.

  17. From malaria parasite point of view – Plasmodium falciparum evolution

    Directory of Open Access Journals (Sweden)

    Agata Zerka

    2015-12-01

    Full Text Available Malaria is caused by infection with protozoan parasites belonging to the genus Plasmodium, which have arguably exerted the greatest selection pressure on humans in the history of our species. Besides humans, different Plasmodium parasites infect a wide range of animal hosts, from marine invertebrates to primates. On the other hand, individual Plasmodium species show high host specificity. The extraordinary evolution of Plasmodium probably began when a free-living red algae turned parasitic, and culminated with its ability to thrive inside a human red blood cell. Studies on the African apes generated new data on the evolution of malaria parasites in general and the deadliest human-specific species, Plasmodium falciparum, in particular. Initially, it was hypothesized that P. falciparum descended from the chimpanzee malaria parasite P. reichenowi, after the human and the chimp lineage diverged about 6 million years ago. However, a recently identified new species infecting gorillas, unexpectedly showed similarity to P. falciparum and was therefore named P. praefalciparum. That finding spurred an alternative hypothesis, which proposes that P. falciparum descended from its gorilla rather than chimp counterpart. In addition, the gorilla-to-human host shift may have occurred more recently (about 10 thousand years ago than the theoretical P. falciparum-P. reichenowi split. One of the key aims of the studies on Plasmodium evolution is to elucidate the mechanisms that allow the incessant host shifting and retaining the host specificity, especially in the case of human-specific species. Thorough understanding of these phenomena will be necessary to design effective malaria treatment and prevention strategies.

  18. [From malaria parasite point of view--Plasmodium falciparum evolution].

    Science.gov (United States)

    Zerka, Agata; Kaczmarek, Radosław; Jaśkiewicz, Ewa

    2015-12-31

    Malaria is caused by infection with protozoan parasites belonging to the genus Plasmodium, which have arguably exerted the greatest selection pressure on humans in the history of our species. Besides humans, different Plasmodium parasites infect a wide range of animal hosts, from marine invertebrates to primates. On the other hand, individual Plasmodium species show high host specificity. The extraordinary evolution of Plasmodium probably began when a free-living red algae turned parasitic, and culminated with its ability to thrive inside a human red blood cell. Studies on the African apes generated new data on the evolution of malaria parasites in general and the deadliest human-specific species, Plasmodium falciparum, in particular. Initially, it was hypothesized that P. falciparum descended from the chimpanzee malaria parasite P. reichenowi, after the human and the chimp lineage diverged about 6 million years ago. However, a recently identified new species infecting gorillas, unexpectedly showed similarity to P. falciparum and was therefore named P. praefalciparum. That finding spurred an alternative hypothesis, which proposes that P. falciparum descended from its gorilla rather than chimp counterpart. In addition, the gorilla-to-human host shift may have occurred more recently (about 10 thousand years ago) than the theoretical P. falciparum-P. reichenowi split. One of the key aims of the studies on Plasmodium evolution is to elucidate the mechanisms that allow the incessant host shifting and retaining the host specificity, especially in the case of human-specific species. Thorough understanding of these phenomena will be necessary to design effective malaria treatment and prevention strategies.

  19. Differential effects of quinoline antimalarials on endocytosis in Plasmodium falciparum.

    Science.gov (United States)

    Roberts, Lindi; Egan, Timothy J; Joiner, Keith A; Hoppe, Heinrich C

    2008-05-01

    The effects of quinoline antimalarials on endocytosis by Plasmodium falciparum was investigated by measuring parasite hemoglobin levels, peroxidase uptake, and transport vesicle content. Mefloquine, quinine, and halofantrine inhibited endocytosis, and chloroquine inhibited vesicle trafficking, while amodiaquine shared both effects. Protease inhibitors moderated hemoglobin perturbations, suggesting a common role for heme binding.

  20. Crystal structure of truncated aspartate transcarbamoylase from Plasmodium falciparum

    NARCIS (Netherlands)

    Lunev, Sergey; Bosch, Soraya S.; Batista, Fernando de Assis; Wrenger, Carsten; Groves, Matthew R.

    The de novo pyrimidine-biosynthesis pathway of Plasmodium falciparum is a promising target for antimalarial drug discovery. The parasite requires a supply of purines and pyrimidines for growth and proliferation and is unable to take up pyrimidines from the host. Direct (or indirect) inhibition of de

  1. Plasmodium falciparum transcriptome analysis reveals pregnancy malaria associated gene expression

    DEFF Research Database (Denmark)

    Tuikue Ndam, Nicaise; Bischoff, Emmanuel; Proux, Caroline

    2008-01-01

    BACKGROUND: Pregnancy-associated malaria (PAM) causing maternal anemia and low birth weight is among the multiple manifestations of Plasmodium falciparum malaria. Infected erythrocytes (iEs) can acquire various adhesive properties that mediate the clinical severity of malaria. Recent advances...

  2. Molecular Surveillance for Multidrug-Resistant Plasmodium falciparum, Cambodia

    Science.gov (United States)

    Shah, Naman K.; Alker, Alisa P.; Sem, Rithy; Susanti, Agustina Ika; Muth, Sinuon; Maguire, Jason D.; Duong, Socheat; Ariey, Frederic; Meshnick, Steven R.

    2008-01-01

    We conducted surveillance for multidrug-resistant Plasmodium falciparum in Cambodia during 2004–2006 by assessing molecular changes in pfmdr1. The high prevalence of isolates with multiple pfmdr1 copies found in western Cambodia near the Thai border, where artesunate–mefloquine therapy failures occur, contrasts with isolates from eastern Cambodia, where this combination therapy remains highly effective. PMID:18826834

  3. Comparative analysis of acon- Plasmodium falciparum rapid malaria ...

    African Journals Online (AJOL)

    Comparative analysis of acon- Plasmodium falciparum rapid malaria diagnostic test with routine microscopy among school children and pregnant women in a rural community in Enugu State, ... The following parameters were determined: intrinsic validity, predictive values, species diagnostic power and logistic factors.

  4. Light microscopic detection of Plasmodium falciparum in vitro ...

    African Journals Online (AJOL)

    Olalekan Michael

    2014-02-19

    Feb 19, 2014 ... Full Length Research Paper. Light microscopic detection of Plasmodium falciparum in vitro through Pf histidine rich protein 2 (HRP 2) gold conjugate labeling: Rapid diagnosis of cerebral malaria in humans. Ogundele Olalekan Michael*1, Saheed Sabiu2, Adekeye Adeshina Oloruntoba1, Adeniyi Philip.

  5. Dhfr and dhps mutations in Plasmodium falciparum isolates in ...

    African Journals Online (AJOL)

    Sulfadoxine-pyrimethamine (SP), the current first line antimalarial drug in Tanzania, is compromised by evolution and spread of mutations in the parasite's dhfr and dhps genes. In the present study we established the baseline frequencies of Plasmodium falciparum dihydrofolate reductase (pfdhfr) and dihydropteroate ...

  6. Cytokine profiles and antibody responses to Plasmodium falciparum ...

    African Journals Online (AJOL)

    Administrator

    †Mathematical Statistics, Stockholm University, SE-106 91 Stockholm, Sweden. Abstract. Background: The ability of the host immune system to efficiently clear Plasmodium falciparum parasites during a malaria infection depends on the type of immune response mounted by the host. Study design: In a cross-sectional study, ...

  7. Origin of the human malaria parasite Plasmodium falciparum in gorillas.

    Science.gov (United States)

    Liu, Weimin; Li, Yingying; Learn, Gerald H; Rudicell, Rebecca S; Robertson, Joel D; Keele, Brandon F; Ndjango, Jean-Bosco N; Sanz, Crickette M; Morgan, David B; Locatelli, Sabrina; Gonder, Mary K; Kranzusch, Philip J; Walsh, Peter D; Delaporte, Eric; Mpoudi-Ngole, Eitel; Georgiev, Alexander V; Muller, Martin N; Shaw, George M; Peeters, Martine; Sharp, Paul M; Rayner, Julian C; Hahn, Beatrice H

    2010-09-23

    Plasmodium falciparum is the most prevalent and lethal of the malaria parasites infecting humans, yet the origin and evolutionary history of this important pathogen remain controversial. Here we develop a single-genome amplification strategy to identify and characterize Plasmodium spp. DNA sequences in faecal samples from wild-living apes. Among nearly 3,000 specimens collected from field sites throughout central Africa, we found Plasmodium infection in chimpanzees (Pan troglodytes) and western gorillas (Gorilla gorilla), but not in eastern gorillas (Gorilla beringei) or bonobos (Pan paniscus). Ape plasmodial infections were highly prevalent, widely distributed and almost always made up of mixed parasite species. Analysis of more than 1,100 mitochondrial, apicoplast and nuclear gene sequences from chimpanzees and gorillas revealed that 99% grouped within one of six host-specific lineages representing distinct Plasmodium species within the subgenus Laverania. One of these from western gorillas comprised parasites that were nearly identical to P. falciparum. In phylogenetic analyses of full-length mitochondrial sequences, human P. falciparum formed a monophyletic lineage within the gorilla parasite radiation. These findings indicate that P. falciparum is of gorilla origin and not of chimpanzee, bonobo or ancient human origin.

  8. Optimization of a protocol for extraction of Plasmodium falciparum ...

    African Journals Online (AJOL)

    This study was carried out to determine the efficiency of two reagents, RNAlater and RNAwiz, for their ability to stabilize Plasmodium falciparum RNA in infected whole blood and saponin lysed parasite pellets for use in DNA microarrays. Eight infected blood samples were stored in each of the reagents, and RNA extracted at ...

  9. Origin of the human malaria parasite Plasmodium falciparum in gorillas

    Science.gov (United States)

    Liu, Weimin; Li, Yingying; Learn, Gerald H.; Rudicell, Rebecca S.; Robertson, Joel D.; Keele, Brandon F.; Ndjango, Jean-Bosco N.; Sanz, Crickette M.; Morgan, David B.; Locatelli, Sabrina; Gonder, Mary K.; Kranzusch, Philip J.; Walsh, Peter D.; Delaporte, Eric; Mpoudi-Ngole, Eitel; Georgiev, Alexander V.; Muller, Martin N.; Shaw, George M.; Peeters, Martine; Sharp, Paul M.; Rayner, Julian C.; Hahn, Beatrice H.

    2010-01-01

    Plasmodium falciparum is the most prevalent and lethal of the malaria parasites infecting humans, yet the origin and evolutionary history of this important pathogen remain controversial. Here, we developed a novel polymerase chain reaction based single genome amplification strategy to identify and characterize Plasmodium spp. DNA sequences in fecal samples of wild-living apes. Among nearly 3,000 specimens collected from field sites throughout central Africa, we found Plasmodium infection in chimpanzees (Pan troglodytes) and western gorillas (Gorilla gorilla), but not in eastern gorillas (Gorilla beringei) or bonobos (Pan paniscus). Ape plasmodial infections were highly prevalent, widely distributed, and almost always comprised of mixed parasite species. Analysis of more than 1,100 mitochondrial, apicoplast and nuclear gene sequences from chimpanzees and gorillas revealed that 99% grouped within one of six host-specific lineages representing distinct Plasmodium species within the subgenus Laverania. One of these from western gorillas was comprised of parasites that were nearly identical to P. falciparum. In phylogenetic analyses of full-length mitochondrial sequences, human P. falciparum formed a monophyletic lineage within the gorilla parasite radiation. These findings indicate that P. falciparum is of gorilla and not of chimpanzee, bonobo or ancient human origin. PMID:20864995

  10. Plasmodium falciparum parasite prevalence in East Africa: A Review ...

    African Journals Online (AJOL)

    Data extraction: Studies of cross-sectional community estimates of Plasmodium falciparum prevalence among children aged 0-15 years were identified from a variety of sources including electronic searches of published material, manual review of pre-electronic peer reviewed journals and searches of libraries and archives ...

  11. Antibodies to a recombinant glutamate-rich Plasmodium falciparum protein

    DEFF Research Database (Denmark)

    Hogh, B; Petersen, E; Dziegiel, Morten Hanefeld

    1992-01-01

    A Plasmodium falciparum antigen gene coding for a 220-kD glutamate-rich protein (GLURP) has been cloned, and the 783 C-terminal amino acids of this protein (GLURP489-1271) have been expressed as a beta-galactosidase fusion protein in Escherichia coli. The encoded 783 amino acid residues contain two...

  12. Positive blood culture with Plasmodium falciparum : Case report

    NARCIS (Netherlands)

    De Vries, Jutte J. C.; Van Assen, Sander; Mulder, André B.; Kampinga, Greetje A.

    2007-01-01

    An adult traveler presented with fever and malaise after returning from Sierra Leone. Young trophozoites of Plasmodium falciparum were seen in a blood smear, with parasitemia being 10%. Moreover, blood cultures drawn on admission signaled as "positive" after 1 day of incubation, but no bacteria were

  13. Chloroquine-resistant Plasmodium falciparum malaria in the ...

    African Journals Online (AJOL)

    The sensitivity to chloroquine of Plasmodium falciparum from the Kavango region of Namibia was determined by a 24-hour test in vitro. Twenty-six Isolates were successfully tested, of which 11 were resistant to a low degree, schizogony being inhibited at 8 pmollwell. The results of the Dill-Glazko test for the presence of ...

  14. Drug-resistant Plasmodium falciparum malaria in the eastern ...

    African Journals Online (AJOL)

    In March 1993, a study was undertaken in the . KomatipoortlMalelane area to monitor the in vitro sensitivity of Plasmodium falciparum to antimalarial drugs currently in use in South Africa. Of the 12 isolates collected, 7 were successfully tested for sensitivity to chloroquine and quinine, 6 for mefloquine susceptibility, and 5 for ...

  15. plasma total chloroquine level in relation to plasmodium falciparum ...

    African Journals Online (AJOL)

    Quantification of plasma total chloroquine level was carried out in relation to Plasmodium falciparum density in 80 adult malaria patients in Calabar. The WHO in Vivo seven-day test was used with follow-up on days 1, 2, 3 and 7 after treatment with 25mg chloroquine base per kilogram body weight. Clinical and ...

  16. Mitosis in the Human Malaria Parasite Plasmodium falciparum

    Science.gov (United States)

    Gerald, Noel; Mahajan, Babita; Kumar, Sanjai

    2011-01-01

    Malaria is caused by intraerythrocytic protozoan parasites belonging to Plasmodium spp. (phylum Apicomplexa) that produce significant morbidity and mortality, mostly in developing countries. Plasmodium parasites have a complex life cycle that includes multiple stages in anopheline mosquito vectors and vertebrate hosts. During the life cycle, the parasites undergo several cycles of extreme population growth within a brief span, and this is critical for their continued transmission and a contributing factor for their pathogenesis in the host. As with other eukaryotes, successful mitosis is an essential requirement for Plasmodium reproduction; however, some aspects of Plasmodium mitosis are quite distinct and not fully understood. In this review, we will discuss the current understanding of the architecture and key events of mitosis in Plasmodium falciparum and related parasites and compare them with the traditional mitotic events described for other eukaryotes. PMID:21317311

  17. Endemicity response timelines for Plasmodium falciparum elimination

    Directory of Open Access Journals (Sweden)

    Hay Simon I

    2009-04-01

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

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

    Directory of Open Access Journals (Sweden)

    Sara N. Mohamed

    2016-01-01

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

  19. Cross-reactive anti-PfCLAG9 antibodies in the sera of asymptomatic parasite carriers of Plasmodium vivax

    Science.gov (United States)

    Costa, Joana D'Arc Neves; Zanchi, Fernando Berton; Rodrigues, Francisco Lurdevanhe da Silva; Honda, Eduardo Rezende; Katsuragawa, Tony Hiroschi; Pereira, Dhélio Batista; Taborda, Roger Lafontaine Mesquita; Tada, Mauro Shugiro; Ferreira, Ricardo de Godoi Mattos; Pereira-da-Silva, Luiz Hildebrando

    2013-01-01

    The PfCLAG9 has been extensively studied because their immunogenicity. Thereby, the gene product is important for therapeutics interventions and a potential vaccine candidate. Antibodies against synthetic peptides corresponding to selected sequences of the Plasmodium falciparum antigen PfCLAG9 were found in sera of falciparum malaria patients from Rondônia, in the Brazilian Amazon. Much higher antibody titres were found in semi-immune and immune asymptomatic parasite carriers than in subjects suffering clinical infections, corroborating original findings in Papua Guinea. However, sera of Plasmodium vivax patients from the same Amazon area, in particular from asymptomatic vivax parasite carriers, reacted strongly with the same peptides. Bioinformatic analyses revealed regions of similarity between P. falciparum Pfclag9 and the P. vivax ortholog Pvclag7. Indirect fluorescent microscopy analysis showed that antibodies against PfCLAG9 peptides elicited in BALB/c mice react with human red blood cells (RBCs) infected with both P. falciparum and P. vivax parasites. The patterns of reactivity on the surface of the parasitised RBCs are very similar. The present observations support previous findings that PfCLAG9 may be a target of protective immune responses and raises the possibility that the cross reactive antibodies to PvCLAG7 in mixed infections play a role in regulate the fate of Plasmodium mixed infections. PMID:23440122

  20. Identification of Protein Markers in Patients Infected with Plasmodium knowlesi, Plasmodium falciparum and Plasmodium vivax

    Directory of Open Access Journals (Sweden)

    Alan Kang-Wai Mu

    2014-11-01

    Full Text Available Malaria is caused by parasitic protozoans of the genus Plasmodium and is one of the most prevalent infectious diseases in tropical and subtropical regions. For this reason, effective and practical diagnostic methods are urgently needed to control the spread of malaria. The aim of the current study was to identify a panel of new malarial markers, which could be used to diagnose patients infected with various Plasmodium species, including P. knowlesi, P. vivax and P. falciparum. Sera from malaria-infected patients were pooled and compared to control sera obtained from healthy individuals using the isobaric tags for relative and absolute quantitation (iTRAQ technique. Mass spectrometry was used to identify serum proteins and quantify their relative abundance. We found that the levels of several proteins were increased in pooled serum from infected patients, including cell adhesion molecule-4 and C-reactive protein. In contrast, the serum concentration of haptoglobin was reduced in malaria-infected individuals, which we verified by western blot assay. Therefore, these proteins might represent infectious markers of malaria, which could be used to develop novel diagnostic tools for detecting P. knowlesi, P. vivax and P. falciparum. However, these potential malarial markers will need to be validated in a larger population of infected individuals.

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

    Science.gov (United States)

    MASON, DANIEL P.; McKENZIE, F. ELLIS

    2008-01-01

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

  2. High prevalence of drug-resistance mutations in Plasmodium falciparum and Plasmodium vivax in southern Ethiopia

    Directory of Open Access Journals (Sweden)

    Löscher Thomas

    2006-07-01

    Full Text Available Abstract Background In Ethiopia, malaria is caused by both Plasmodium falciparum and Plasmodium vivax. Drug resistance of P. falciparum to sulfadoxine-pyrimethamine (SP and chloroquine (CQ is frequent and intense in some areas. Methods In 100 patients with uncomplicated malaria from Dilla, southern Ethiopia, P. falciparum dhfr and dhps mutations as well as P. vivax dhfr polymorphisms associated with resistance to SP and P. falciparum pfcrt and pfmdr1 mutations conferring CQ resistance were assessed. Results P. falciparum and P. vivax were observed in 69% and 31% of the patients, respectively. Pfdhfr triple mutations and pfdhfr/pfdhps quintuple mutations occurred in 87% and 86% of P. falciparum isolates, respectively. Pfcrt T76 was seen in all and pfmdr1 Y86 in 81% of P. falciparum. The P. vivax dhfr core mutations N117 and R58 were present in 94% and 74%, respectively. Conclusion These data point to an extraordinarily high frequency of drug-resistance mutations in both P. falciparum and P. vivax in southern Ethiopia, and strongly support that both SP and CQ are inadequate drugs for this region.

  3. On Programmed Cell Death in Plasmodium falciparum: Status Quo

    Directory of Open Access Journals (Sweden)

    Dewaldt Engelbrecht

    2012-01-01

    Full Text Available Conflicting arguments and results exist regarding the occurrence and phenotype of programmed cell death (PCD in the malaria parasite Plasmodium falciparum. Inconsistencies relate mainly to the number and type of PCD markers assessed and the different methodologies used in the studies. In this paper, we provide a comprehensive overview of the current state of knowledge and empirical evidence for PCD in the intraerythrocytic stages of P. falciparum. We consider possible reasons for discrepancies in the data and offer suggestions towards more standardised investigation methods in this field. Furthermore, we present genomic evidence for PCD machinery in P. falciparum. We discuss the potential adaptive or nonadaptive role of PCD in the parasite life cycle and its possible exploitation in the development of novel drug targets. Lastly, we pose pertinent unanswered questions concerning the PCD phenomenon in P. falciparum to provide future direction.

  4. On Programmed Cell Death in Plasmodium falciparum: Status Quo

    Science.gov (United States)

    Engelbrecht, Dewaldt; Durand, Pierre Marcel; Coetzer, Thérèsa Louise

    2012-01-01

    Conflicting arguments and results exist regarding the occurrence and phenotype of programmed cell death (PCD) in the malaria parasite Plasmodium falciparum. Inconsistencies relate mainly to the number and type of PCD markers assessed and the different methodologies used in the studies. In this paper, we provide a comprehensive overview of the current state of knowledge and empirical evidence for PCD in the intraerythrocytic stages of P. falciparum. We consider possible reasons for discrepancies in the data and offer suggestions towards more standardised investigation methods in this field. Furthermore, we present genomic evidence for PCD machinery in P. falciparum. We discuss the potential adaptive or nonadaptive role of PCD in the parasite life cycle and its possible exploitation in the development of novel drug targets. Lastly, we pose pertinent unanswered questions concerning the PCD phenomenon in P. falciparum to provide future direction. PMID:22287973

  5. High prevalence of asymptomatic plasmodium infection in a suburb ...

    African Journals Online (AJOL)

    Background: Malaria is endemic in many parts of the world. Various strategies have been planned to control malaria from time to time in many places. Whatever may be the strategy the prevalence of symptomatic and asymptomatic plasmodium parasitaemics has been of prime importance as useful parameter for its control.

  6. Impact of climate variability on Plasmodium vivax and Plasmodium falciparum malaria in Yunnan Province, China

    OpenAIRE

    Bi, Yan; Yu, Weiwei; Hu, Wenbiao; Lin, Hualiang; Guo, Yuming; Zhou, Xiao-Nong; Tong, Shilu

    2013-01-01

    Background Malaria remains a public health problem in the remote and poor area of Yunnan Province, China. Yunnan faces an increasing risk of imported malaria infections from Mekong river neighboring countries. This study aimed to identify the high risk area of malaria transmission in Yunnan Province, and to estimate the effects of climatic variability on the transmission of Plasmodium vivax and Plasmodium falciparum in the identified area. Methods We identified spatial clusters of malaria cas...

  7. Plasmodium falciparum dihydrofolate reductase alleles and pyrimethamine use in pregnant Ghanaian women

    NARCIS (Netherlands)

    Mockenhaupt, F. P.; Eggelte, T. A.; Böhme, T.; Thompson, W. N.; Bienzle, U.

    2001-01-01

    Drug resistance in Plasmodium falciparum affects prevention of malaria in pregnancy. In a cross-sectional study of 530 pregnant Ghanaian women, P. falciparum dihydrofolate reductase (DHFR) gene mutations linked with pyrimethamine resistance were assessed and associations with pyrimethamine intake

  8. Polymorphisms in Plasmodium falciparum chloroquine resistance transporter and multidrug resistance 1 genes

    DEFF Research Database (Denmark)

    Venkatesan, Meera; Gadalla, Nahla B; Stepniewska, Kasia

    2014-01-01

    Adequate clinical and parasitologic cure by artemisinin combination therapies relies on the artemisinin component and the partner drug. Polymorphisms in the Plasmodium falciparum chloroquine resistance transporter (pfcrt) and P. falciparum multidrug resistance 1 (pfmdr1) genes are associated...

  9. Loss of cellular immune reactivity during acute Plasmodium falciparum malaria

    DEFF Research Database (Denmark)

    Hviid, L; Theander, T G; Abu-Zeid, Y A

    1991-01-01

    convalescence. Five donors examined by fluorescence-activated cell sorting (FACS) showed no increase in surface expression of IL-2 receptor on peripheral lymphocytes. The data indicate that acute P. falciparum malaria causes a depletion of antigen-reactive T-cells from the peripheral circulation, probably due......Sixteen patients suffering from acute Plasmodium falciparum malaria were studied. All were residents of an area of unstable malaria-transmission in Eastern Sudan. Blood-samples were drawn at diagnosis, and 7 and 30 days later. Blood-samples from thirteen donors, drawn outside the malaria...

  10. Antibodies to a recombinant glutamate-rich Plasmodium falciparum protein

    DEFF Research Database (Denmark)

    Hogh, B; Petersen, E; Dziegiel, M

    1992-01-01

    A Plasmodium falciparum antigen gene coding for a 220-kD glutamate-rich protein (GLURP) has been cloned, and the 783 C-terminal amino acids of this protein (GLURP489-1271) have been expressed as a beta-galactosidase fusion protein in Escherichia coli. The encoded 783 amino acid residues contain two...... areas of repeated amino acid sequences. Antibodies against recombinant GLURP489-1271, as well as against a synthetic peptide corresponding to GLURP899-916, and against a synthetic peptide representing the major glutamate rich repeat sequence from the P. falciparum ring erythrocyte surface antigen (Pf155...

  11. Loss of cellular immune reactivity during acute Plasmodium falciparum malaria

    DEFF Research Database (Denmark)

    Hviid, L; Theander, T G; Abu-Zeid, Y A

    1991-01-01

    Sixteen patients suffering from acute Plasmodium falciparum malaria were studied. All were residents of an area of unstable malaria-transmission in Eastern Sudan. Blood-samples were drawn at diagnosis, and 7 and 30 days later. Blood-samples from thirteen donors, drawn outside the malaria...... convalescence. Five donors examined by fluorescence-activated cell sorting (FACS) showed no increase in surface expression of IL-2 receptor on peripheral lymphocytes. The data indicate that acute P. falciparum malaria causes a depletion of antigen-reactive T-cells from the peripheral circulation, probably due...

  12. Substantial asymptomatic submicroscopic Plasmodium carriage during dry season in low transmission areas in Senegal: Implications for malaria control and elimination.

    Science.gov (United States)

    Niang, Makhtar; Thiam, Laty Gaye; Sane, Rokhaya; Diagne, Nafissatou; Talla, Cheikh; Doucoure, Souleymane; Faye, Joseph; Diop, Fode; Badiane, Abdoulaye; Diouf, Babacar; Camara, Diogop; Diene-Sarr, Fatoumata; Sokhna, Cheikh; Richard, Vincent; Toure-Balde, Aissatou

    2017-01-01

    In the progress towards malaria elimination, the accurate diagnosis of low-density asymptomatic infections is critical. Low-density asymptomatic submicroscopic malaria infections may act as silent reservoirs that maintain low-level residual malaria transmission in the community. Light microscopy, the gold standard in malaria diagnosis lacks the sensitivity to detect low-level parasitaemia. In this study, the presence and prevalence of submicroscopic Plasmodium carriage were investigated to estimate the parasites reservoir among asymptomatic individuals living in low transmission areas in Dielmo and Ndiop, Senegal during the dry season. A total of 2,037 blood samples were collected during cross-sectional surveys prior the malaria transmission season in July 2013 (N = 612), June 2014 (N = 723) and June 2015 (N = 702) from asymptomatic individuals living in Dielmo and Ndiop, Senegal. Samples were used to determine the prevalence of submicroscopic Plasmodium carriage by real time PCR (qPCR) in comparison to microscopy considered as gold standard. The prevalence of submicroscopic Plasmodium carriage was 3.75% (23/612), 12.44% (90/723) and 6.41% (45/702) in 2013, 2014 and 2015, respectively. No Plasmodium carriage was detected by microscopy in 2013 while microscopy-based prevalence of Plasmodium carriage accounted for only 0.27% (2/723) and 0.14% (1/702) in 2014 and 2015, respectively. Plasmodium falciparum accounted for the majority of submicroscopic infections and represented 86.95% (20/23), 81.11% (73/90) and 95.55 (43/45) of infections in 2013, 2014 and 2015 respectively. Low-density submicroscopic asymptomatic Plasmodium carriage is common in the study areas during the dry season indicating that traditional measures are insufficient to assess the scale of parasite reservoir when transmission reaches very low level. Control and elimination strategies may wish to consider using molecular methods to identify parasites carriers to guide Mass screening and Treatment

  13. The Plasmodium falciparum Sexual Development Transcriptome: A Microarray Analysis using Ontology-Based Pattern Identification

    National Research Council Canada - National Science Library

    Young, Jason A; Fivelman, Quinton L; Blair, Peter L; de la Vega, Patricia; Le Roch, Karine G; Zhou, Yingyao; Carucci, Daniel J; Baker, David A; Winzeler, Elizabeth A

    2005-01-01

    .... In order to better understand genes important to the sexual development process, the transcriptomes of high-purity stage I V Plasmodium falciparum gametocytes were comprehensively profiled using...

  14. Plasmodium falciparum associated with severe childhood malaria preferentially expresses PfEMP1 encoded by group A var genes

    DEFF Research Database (Denmark)

    Jensen, Anja T R; Magistrado, Pamela; Sharp, Sarah

    2004-01-01

    Parasite-encoded variant surface antigens (VSAs) like the var gene-encoded Plasmodium falciparum erythrocyte membrane protein 1 (PfEMP1) family are responsible for antigenic variation and infected red blood cell (RBC) cytoadhesion in P. falciparum malaria. Parasites causing severe malaria...... in nonimmune patients tend to express a restricted subset of VSA (VSA(SM)) that differs from VSA associated with uncomplicated malaria and asymptomatic infection (VSA(UM)). We compared var gene transcription in unselected P. falciparum clone 3D7 expressing VSA(UM) to in vitro-selected sublines expressing VSA...... genes, such as PFD1235w/MAL7P1.1, appear to be involved in the pathogenesis of severe disease and are thus attractive candidates for a vaccine against life-threatening P. falciparum malaria....

  15. Afebrile Plasmodium falciparum parasitemia decreases absorption of fortification iron but does not affect systemic iron utilization: a double stable-isotope study in young Beninese women

    NARCIS (Netherlands)

    Cercamondi, C.I.; Egli, I.; Ahouandjinou, E.; Dossa, R.A.M.; Zeder, C.; Salami, I.; Tjalsma, H.; Wiegerinck, E.; Tanno, T.; Hurrell, R.F.; Hounhouigan, J.D.; Zimmermann, M.B.

    2010-01-01

    Background: Iron deficiency anemia (IDA) affects many young women in sub-Saharan Africa. Its etiology is multifactorial, but the major cause is low dietary iron bioavailability exacerbated by parasitic infections such as malaria. Objective: We investigated whether asymptomatic Plasmodium falciparum

  16. Afebrile Plasmodium falciparum parasitemia decreases absorption of fortification iron but does not affect systemic iron utilization: a double stable-isotope study in young Beninese women.

    NARCIS (Netherlands)

    Cercamondi, C.I.; Egli, I.M.; Ahouandjinou, E.; Dossa, R.; Zeder, C.; Salami, L.; Tjalsma, H.; Wiegerinck, E.T.G.; Tanno, T.; Hurrell, R.F.; Hounhouigan, J.; Zimmermann, M.B.

    2010-01-01

    BACKGROUND: Iron deficiency anemia (IDA) affects many young women in sub-Saharan Africa. Its etiology is multifactorial, but the major cause is low dietary iron bioavailability exacerbated by parasitic infections such as malaria. OBJECTIVE: We investigated whether asymptomatic Plasmodium falciparum

  17. Detection of very low level Plasmodium falciparum infections using the nested polymerase chain reaction and a reassessment of the epidemiology of unstable malaria in Sudan

    DEFF Research Database (Denmark)

    Roper, C; Elhassan, I M; Hviid, L

    1996-01-01

    We have used the nested polymerase chain reaction (PCR) to assay for low level Plasmodium falciparum infections that were below the threshold of detection of blood film examination. This revealed a substantial group of asymptomatic, submicroscopically patent infections within the population of a ...

  18. Tetanus toxoid antibody level in asymptomatic Plasmodium ...

    African Journals Online (AJOL)

    The present study was designed to investigate if the presence of asymptomatic malaria parasiteamia in pregnant women will compromise their ability to respond to full dose of tetanus toxoid immunization during their antenatal clinic visits. Hence, 90 apparently healthy pregnant women who had completed the tetanus toxoid ...

  19. Serological evidence of discrete spatial clusters of Plasmodium falciparum parasites

    DEFF Research Database (Denmark)

    Bejon, Philip; Turner, Louise; Lavstsen, Thomas

    2011-01-01

    Malaria transmission may be considered to be homogenous with well-mixed parasite populations (as in the classic Ross/Macdonald models). Marked fine-scale heterogeneity of transmission has been observed in the field (i.e., over a few kilometres), but there are relatively few data on the degree...... of mixing. Since the Plasmodium falciparum Erythrocyte Membrane Protein 1 (PfEMP1) is highly polymorphic, the host's serological responses may be used to infer exposure to parasite sub-populations....

  20. Sensitivity of Plasmodium falciparum to antimalarial drugs in Colombia.

    Science.gov (United States)

    Espinal, C A; Cortes, G T; Guerra, P; Arias, A E

    1985-07-01

    Sensitivity of Plasmodium falciparum to several antimalarial drugs was determined by in vitro and in vivo tests. Chloroquine resistance in vitro was detected in 97 of 101 patients from different geographic areas of Colombia. Sensitivity to amodiaquine in vitro was observed in 29 of 30 P. falciparum isolates. In vitro sensitivity to amodiaquine was observed in 16 patients infected with chloroquine-resistant P. falciparum. In vitro sensitivity to quinine was demonstrated in 57 P. falciparum isolates. Two infections from the Amazon base (2/24) were resistant to mefloquine in vitro at concentrations of 5.7 and 16 pmol/well. Resistance to Fansidar, a sulfadoxine-pyrimethamine combination, was described in 9 patients from the Amazon region. One patient showed recrudescence of the infection 41 days after treatment. The current distribution and degree of resistance of P. falciparum to widely used antimalarial drugs requires the evaluation of therapeutic schemes based on combinations of fast blood schizontocides with slow acting drugs. These associations may reduce the development of multidrug-resistant isolates and retard the spread of resistant populations of P. falciparum parasites.

  1. Plasmodium falciparum malaria associated with ABO blood ...

    African Journals Online (AJOL)

    The present study was carried out to investigate the relationship between blood group types and P. falciparum malaria, as well as malaria preventive measures. The venous blood specimens were collected, processed, Giemsa-stained and examined microscopically. ABO groups were determined by agglutination test using ...

  2. Plasmodium falciparum malaria and antimalarial interventions in ...

    African Journals Online (AJOL)

    Administrator

    direct and indirect costs, and has been shown to be a major constraint to economic development (Sacks ... to 30% of all hospital admissions and is responsible for. 15 to 25% of all deaths of children under the age ..... However, following reports of its resistance to P. falciparum in 1960 from Colombia and subsequent report.

  3. A Case Report of Plasmodium Vivax, Plasmodium Falciparum and ...

    African Journals Online (AJOL)

    Although infection with P. vivax, P. falciparum, dengue and leptospira has been reported,[3] but so far no case of a mixed infection during pregnancy has been reported. Case Report. A 25‑year‑old 6 months pregnant lady from a rural background was admitted to a private tertiary care hospital in north India with complaints of ...

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

    Science.gov (United States)

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

    2011-12-19

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

  5. Diversity of Plasmodium falciparum clones infecting children living in a holoendemic area in north-eastern Tanzania

    DEFF Research Database (Denmark)

    Magesa, S M; Mdira, K Y; Babiker, H A

    2002-01-01

    The diversity of Plasmodium falciparum clones and their role in progression from asymptomatic to symptomatic condition in children have been investigated. Attempts to identify whether particular parasite genotypes were associated with the development of clinical symptoms have been made. A cohort...... were found to be highly complex in both groups of children. Every isolate examined from both groups had a mixture of parasite clones. Daily changes were observed in both parasite density and genotypic pattern. The mean number of genotypes per individual was estimated at 4.9 and 2.7 for asymptomatic...

  6. Relationship of regulatory T cells to Plasmodium falciparum malaria symptomatology in a hypoendemic region.

    Science.gov (United States)

    Torres, Katherine J; Villasis, Elizabeth; Bendezú, Jorge; Chauca, José; Vinetz, Joseph M; Gamboa, Dionicia

    2014-03-19

    Previous data have suggested that regulatory T cells (Tregs) balance protective immune responses with immune mediated pathology in malaria. This study aimed to determine to test the hypothesis that Treg proportions or absolute levels are associated with parasitaemia and malaria symptoms. Treg cells were quantified by flow cytometry as CD4+ CD25+, Foxp3+, CD127(low) T cells. Three patient groups were assessed: patients with symptomatic Plasmodium falciparum malaria (S), subjects with asymptomatic P. falciparum parasitaemia (AS) and uninfected control individuals (C). S, AS and C groups had similar absolute numbers and percentage of Tregs (3.9%, 3.5% and 3.5% respectively). Levels of parasitaemia were not associated with Treg percentage (p = 0.47). Neither relative nor absolute regulatory T cell numbers were found to be associated with malaria-related symptomatology in this study. Immune mechanisms other than Tregs are likely to be responsible for the state of asymptomatic P. falciparum parasitaemia in the Peruvian Amazon; but further study to explore these mechanisms is needed.

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

    Science.gov (United States)

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

    2013-01-01

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

  8. Malária por Plasmodium falciparum: estudos proteômicos Plasmodium falciparum malaria: proteomic studies

    Directory of Open Access Journals (Sweden)

    Rodrigo Siqueira-Batista

    2012-12-01

    Full Text Available A despeito dos avanços no tratamento e das campanhas de prevenção e de controle da malária nos distintos continentes nos quais a moléstia grassa, a entidade mórbida permanece com significativa relevância no mundo contemporâneo. O Plasmodium falciparum é o grande responsável pela malária grave, caracterizada por distúrbios em diferentes órgãos e sistemas, com possibilidade de evolução ao óbito. Embora incipientes, os estudos proteômicos na malária têm trazido boas perspectivas para melhor compreensão dos aspectos biológicos do Plasmodium, assim como dos mecanismos fisiopatológicos, diagnósticos, terapêuticos e profiláticos da enfermidade. Desse modo, o objetivo do presente artigo é apresentar uma breve revisão das aplicações da análise proteômica na malária por P. falciparum.Despite advances in treatment and campaigns for prevention and control of malaria on the various continents where it is still rampant, this disease remains significantly relevant to the contemporary world. Plasmodium falciparum is the organism that is mainly responsible for severe malaria, which is characterized by disturbances in different organs and systems, with possibly fatal outcomes. Although incipient, proteomic studies of malaria have yielded favorable prospects for elucidating the biological aspects of Plasmodium as well as the pathophysiological, diagnostic, prophylactic, and therapeutic mechanisms of the disease. Thus, the aim of the present article is to present a brief review of the applications of proteomic analysis in P. falciparum malaria.

  9. Resistência do Plasmodium falciparum ao fansidar, quinina e tetraciclina Resistance of Plasmodium falciparum to fansidar, quinine and tetracycline

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    Fernando Hélio Alencar

    1982-10-01

    Full Text Available Descreve-se pela primeira vez uma cêpa amazônica de Plasmodium falciparum resistente ao Fansidar (pirimetamina mais sulfadoxina e quinino mais tetraciclina simultaneamente. O paciente, com 13 anos de idade, residia há cinco anos em Ariquemes, Estado de Rondônia, na Amazônia brasileira. A infecção foi curada com dose elevada de cloroquina administrada em dose única intravenosa (IV. É evidenciado o alto valor da cloroquina na cura da malária falciparum resistente, quando administrada em doses maiores que as usadas nos esquemas convencionais de tratamento.For the first time an Amazonian strain of Plasmodium falciparum resistant to FansidarR (pyrimethamine + sulfadoxine and quinine + tetracycline, taken sequentially is described. This case involves a female patient 13 years old, living for five years in Ariquemes County, State of Rondônia, in the Brazilian Amazon. The infection was cured with a single high dose of chloroquine administered intravenously. The authors point out the high valor of chloroquine in treating falciparum-resistant malaria, especially when given in higher doses than the standard one used for malaria therapy.

  10. Asymptomatic falciparum malaria and intestinal helminths co-infection among school children in Osogbo, Nigeria

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    Olusola Ojurongbe

    2011-01-01

    Full Text Available Background: Malaria and intestinal helminths are parasitic diseases causing high morbidity and mortality in most tropical parts of the world, where climatic conditions and sanitation practices favor their prevalence. The aim of this study was to determine the prevalence and possible impact of falciparum malaria and intestinal helminths co-infection among school children in Kajola, Osun state, Nigeria. Methods: Fresh stool and blood samples were collected from 117 primary school children age range 4-15 years. The stool samples were processed using both Kato-Katz and formol-ether concentration techniques and microscopically examined for intestinal parasitic infections. Blood was collected by finger prick to determine malaria parasitemia using thick film method; and packed cell volume (PCV was determined by hematocrit. Univariate analysis and chi-square statistical tests were used to analyze the data. Results: The prevalence of Plasmodium falciparum, intestinal helminth infections, and co-infection of malaria and helminth in the study were 25.6%, 40.2% and 4.3%, respectively. Five species of intestinal helminths were recovered from the stool samples and these were Ascaris lumbricoides (34.2%, hookworm (5.1%, Trichuris trichiura (2.6%, Diphyllobothrium latum (0.9% and Trichostrongylus species (0.9%. For the co-infection of both malaria and intestinal helminths, females (5.9% were more infected than males (2.0% but the difference was not statistically significant (p = 0.3978. Children who were infected with helminths were equally likely to be infected with malaria as children without intestinal helminths [Risk Ratio (RR = 0.7295]. Children with A. lumbricoides (RR = 1.359 were also likely to be infected with P. falciparum as compared with uninfected children. Conclusions: Asymptomatic falciparum malaria and intestinal helminth infections do co-exist without clinical symp-toms in school children in Nigeria.

  11. Cytokine profiles and antibody responses to Plasmodium falciparum ...

    African Journals Online (AJOL)

    Estimated higher ratios of IFN-γ/IL-10 and IFN-γ/IL-12 were also observed in the symptomatic children while the asymptomatic controls had higher IL-12/IL-10 ratio. The mean concentration levels of anti-P. falciparum IgG1, IgG2, IgG3 antibodies were statistically significantly higher in the individuals >5 years of age than <5 ...

  12. Dynamics of Plasmodium falciparum alleles in children with normal haemoglobin and with sickle cell trait in western Uganda.

    Science.gov (United States)

    Kiwanuka, Gertrude N; Joshi, Hema; Isharaza, William K; Eschrich, Klaus

    2009-01-01

    We describe the diversity of Plasmodium falciparum populations in western Uganda and assess the role that asymptomatic malaria carriers with sickle cell trait (HbAS) may be playing on the Plasmodium population structure. We genotyped P. falciparum in 291 samples using merozoite surface protein (MSP) 1 and 2 loci. Extensive genetic diversity was detected among symptomatic children in Mbarara (20 MSP1 alleles; 31 MSP2 alleles) and Kagando, Kasese (19 MSP1 alleles; 30 MSP2 alleles). Multiplicity of infection (MOI) was significantly higher in Kagando, Kasese than in Mbarara, with 2.7 and 2.1 genotypes/PCR positive sample with MSP2 marker, respectively. Similar strains were circulating in the two sites; however, a few strains specific to individual sites were observed. Prevalence of HbAS was 36% (12/33) among asymptomatic children in Kisinga sub-county, Kasese. In asymptomatic children, MOI was age-dependent and higher in HbAS carriers than HbAA, suggesting that HbAS carriers harbour a wider range of P. falciparum genotypes. Sickle cell trait may influence rapid acquisition of premunition by creating a reservoir of variant parasite strains in the host. The high level of genetic diversity demonstrated here shows that even in areas with low or seasonal transmission, high levels of parasite polymorphism can occur.

  13. Sharing of antigens between Plasmodium falciparum and Anopheles albimanus Antígenos compartidos entre Plasmodium falciparum y Anopheles albimanus

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    Albina Wide

    2006-12-01

    Full Text Available The presence of common antigens between Plasmodium falciparum and Anopheles albimanus was demonstrated. Different groups of rabbits were immunized with: crude extract from female An. albimanus (EAaF, red blood cells infected with Plasmodium falciparum (EPfs, and the SPf66 synthetic malaria vaccine. The rabbit's polyclonal antibodies were evaluated by ELISA, Multiple Antigen Blot Assay (MABA, and immunoblotting. All extracts were immunogenic in rabbits according to these three techniques, when they were evaluated against the homologous antigens. Ten molecules were identified in female mosquitoes and also in P. falciparum antigens by the autologous sera. The electrophoretic pattern by SDS-PAGE was different for the three antigens evaluated. Cross-reactions between An. albimanus and P. falciparum were found by ELISA, MABA, and immunoblotting. Anti-P. falciparum and anti-SPf66 antibodies recognized ten and five components in the EAaF crude extract, respectively. Likewise, immune sera against female An. albimanus identified four molecules in the P. falciparum extract antigen. As far as we know, this is the first work that demonstrates shared antigens between anophelines and malaria parasites. This finding could be useful for diagnosis, vaccines, and the study of physiology of the immune response to malaria.Epítopes de antígenos compartidos entre Plasmodium falciparum y Anopheles albimanus fueron identificados. Diferentes grupos de conejos fueron inmunizados con: extracto crudo de mosquito hembra de An. albimanus (EAaH, glóbulos rojos infectados con P. falciparum (EPfs y la vacuna antimalárica sintética SPf66. Los anticuerpos policlonales producidos en conejos fueron evaluados por ELISA, inmunoensayo simultáneo de múltiples antígenos (MABA e Immunoblotting. Todos los extractos resultaron inmunogénicos cuando se evaluaron por ELISA, MABA e Immunoblotting. Diez moléculas fueron identificadas en los mosquitos hembras y diez en los antígenos de

  14. Laser-induced inactivation of Plasmodium falciparum.

    Science.gov (United States)

    LeBlanc, Danielle; Story, Robert; Gross, Eitan

    2012-08-08

    Haemozoin crystals, produced by Plasmodium during its intra-erythrocytic asexual reproduction cycle, can generate UV light via the laser-induced, non-linear optical process of third harmonic generation (THG). In the current study the feasibility of using haemozoin, constitutively stored in the parasite's food vacuole, to kill the parasite by irradiation with a near IR laser was evaluated. Cultured Plasmodium parasites at different stages of development were irradiated with a pulsed NIR laser and the viability of parasites at each stage was evaluated from their corresponding growth curves using the continuous culture method. Additional testing for germicidal effects of haemozoin and NIR laser was performed by adding synthetic haemozoin crystals to Escherichia coli in suspension. Cell suspensions were then irradiated with the laser and small aliquots taken and spread on agar plates containing selective agents to determine cell viability (CFU). Parasites in the late-trophozoites form as well as trophozoites in early-stage of DNA synthesis were found to be the most sensitive to the treatment with -4-log reduction in viability after six passes through the laser beam; followed by parasites in ring phase (-2-log reduction). A -1-log reduction in E. coli viability was obtained following a 60 min irradiation regimen of the bacteria in the presence of 1 μM synthetic haemozoin and a -2-log reduction in the presence of 10 μM haemozoin. Minimal (≤ 15%) cell kill was observed in the presence of 10 μM haemin. Laser-induced third-harmonic generation by haemozoin can be used to inactivate Plasmodium. This result may have clinical implications for treating severe malaria symptoms by irradiating the patient's blood through the skin or through dialysis tubing with a NIR laser.

  15. Laser-induced inactivation of Plasmodium falciparum

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    LeBlanc Danielle

    2012-08-01

    Full Text Available Abstract Background Haemozoin crystals, produced by Plasmodium during its intra-erythrocytic asexual reproduction cycle, can generate UV light via the laser-induced, non-linear optical process of third harmonic generation (THG. In the current study the feasibility of using haemozoin, constitutively stored in the parasite’s food vacuole, to kill the parasite by irradiation with a near IR laser was evaluated. Methods Cultured Plasmodium parasites at different stages of development were irradiated with a pulsed NIR laser and the viability of parasites at each stage was evaluated from their corresponding growth curves using the continuous culture method. Additional testing for germicidal effects of haemozoin and NIR laser was performed by adding synthetic haemozoin crystals to Escherichia coli in suspension. Cell suspensions were then irradiated with the laser and small aliquots taken and spread on agar plates containing selective agents to determine cell viability (CFU. Results Parasites in the late-trophozoites form as well as trophozoites in early-stage of DNA synthesis were found to be the most sensitive to the treatment with ~4-log reduction in viability after six passes through the laser beam; followed by parasites in ring phase (~2-log reduction. A ~1-log reduction in E. coli viability was obtained following a 60 min irradiation regimen of the bacteria in the presence of 1 μM synthetic haemozoin and a ~2-log reduction in the presence of 10 μM haemozoin. Minimal (≤15% cell kill was observed in the presence of 10 μM haemin. Conclusions Laser-induced third-harmonic generation by haemozoin can be used to inactivate Plasmodium. This result may have clinical implications for treating severe malaria symptoms by irradiating the patient’s blood through the skin or through dialysis tubing with a NIR laser.

  16. Transportproteiner som drug-targets hos Plasmodium falciparum. Nye perspektiver i behandlingen af malaria

    DEFF Research Database (Denmark)

    Ellekvist, Peter; Colding, Hanne

    2006-01-01

    The malaria parasite, Plasmodium falciparum, infects and replicates in human erythrocytes. Through the use of substrate-specific transport proteins, P. falciparum takes up nutrients from the erythrocyte's cytoplasm. The sequencing and publishing of the P. falciparum genome have made it possible...

  17. Plasmodium falciparum Malaria Endemicity in Indonesia in 2010

    Science.gov (United States)

    Elyazar, Iqbal R. F.; Gething, Peter W.; Patil, Anand P.; Rogayah, Hanifah; Kusriastuti, Rita; Wismarini, Desak M.; Tarmizi, Siti N.; Baird, J. Kevin; Hay, Simon I.

    2011-01-01

    Background Malaria control programs require a detailed understanding of the contemporary spatial distribution of infection risk to efficiently allocate resources. We used model based geostatistics (MBG) techniques to generate a contemporary map of Plasmodium falciparum malaria risk in Indonesia in 2010. Methods Plasmodium falciparum Annual Parasite Incidence (PfAPI) data (2006–2008) were used to map limits of P. falciparum transmission. A total of 2,581 community blood surveys of P. falciparum parasite rate (PfPR) were identified (1985–2009). After quality control, 2,516 were included into a national database of age-standardized 2–10 year old PfPR data (PfPR2–10) for endemicity mapping. A Bayesian MBG procedure was used to create a predicted surface of PfPR2–10 endemicity with uncertainty estimates. Population at risk estimates were derived with reference to a 2010 human population count surface. Results We estimate 132.8 million people in Indonesia, lived at risk of P. falciparum transmission in 2010. Of these, 70.3% inhabited areas of unstable transmission and 29.7% in stable transmission. Among those exposed to stable risk, the vast majority were at low risk (93.39%) with the reminder at intermediate (6.6%) and high risk (0.01%). More people in western Indonesia lived in unstable rather than stable transmission zones. In contrast, fewer people in eastern Indonesia lived in unstable versus stable transmission areas. Conclusion While further feasibility assessments will be required, the immediate prospects for sustained control are good across much of the archipelago and medium term plans to transition to the pre-elimination phase are not unrealistic for P. falciparum. Endemicity in areas of Papua will clearly present the greatest challenge. This P. falciparum endemicity map allows malaria control agencies and their partners to comprehensively assess the region-specific prospects for reaching pre-elimination, monitor and evaluate the effectiveness of

  18. In silico discovery of transcription regulatory elements in Plasmodium falciparum

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    Le Roch Karine G

    2008-02-01

    Full Text Available Abstract Background With the sequence of the Plasmodium falciparum genome and several global mRNA and protein life cycle expression profiling projects now completed, elucidating the underlying networks of transcriptional control important for the progression of the parasite life cycle is highly pertinent to the development of new anti-malarials. To date, relatively little is known regarding the specific mechanisms the parasite employs to regulate gene expression at the mRNA level, with studies of the P. falciparum genome sequence having revealed few cis-regulatory elements and associated transcription factors. Although it is possible the parasite may evoke mechanisms of transcriptional control drastically different from those used by other eukaryotic organisms, the extreme AT-rich nature of P. falciparum intergenic regions (~90% AT presents significant challenges to in silico cis-regulatory element discovery. Results We have developed an algorithm called Gene Enrichment Motif Searching (GEMS that uses a hypergeometric-based scoring function and a position-weight matrix optimization routine to identify with high-confidence regulatory elements in the nucleotide-biased and repeat sequence-rich P. falciparum genome. When applied to promoter regions of genes contained within 21 co-expression gene clusters generated from P. falciparum life cycle microarray data using the semi-supervised clustering algorithm Ontology-based Pattern Identification, GEMS identified 34 putative cis-regulatory elements associated with a variety of parasite processes including sexual development, cell invasion, antigenic variation and protein biosynthesis. Among these candidates were novel motifs, as well as many of the elements for which biological experimental evidence already exists in the Plasmodium literature. To provide evidence for the biological relevance of a cell invasion-related element predicted by GEMS, reporter gene and electrophoretic mobility shift assays

  19. Plasmodium falciparum erythrocyte membrane protein 1 domain cassettes 8 and 13 are associated with severe malaria in children

    DEFF Research Database (Denmark)

    Lavstsen, Thomas; Turner, Louise; Saguti, Fredy

    2012-01-01

    The clinical outcome of Plasmodium falciparum infections ranges from asymptomatic parasitemia to severe malaria syndromes associated with high mortality. The virulence of P. falciparum infections is associated with the type of P. falciparum erythrocyte membrane protein 1 (PfEMP1) expressed...... amplifying var subtype-specific loci covering most var/PfEMP1 subtypes. In addition, we characterized the near-full-length sequence of the most prominently expressed var genes in three patients diagnosed with severe anemia and/or cerebral malaria. The combined analysis showed that severe malaria syndromes......, including severe anemia and cerebral malaria, are associated with high transcript levels of PfEMP1 domain cassette 8-encoding var genes. Transcript levels of group A var genes, including genes encoding domain cassette 13, were also significantly higher in patients with severe syndromes compared with those...

  20. Antibodies to a recombinant glutamate-rich Plasmodium falciparum protein

    DEFF Research Database (Denmark)

    Hogh, B; Petersen, E; Dziegiel, M

    1992-01-01

    A Plasmodium falciparum antigen gene coding for a 220-kD glutamate-rich protein (GLURP) has been cloned, and the 783 C-terminal amino acids of this protein (GLURP489-1271) have been expressed as a beta-galactosidase fusion protein in Escherichia coli. The encoded 783 amino acid residues contain two...... areas of repeated amino acid sequences. Antibodies against recombinant GLURP489-1271, as well as against a synthetic peptide corresponding to GLURP899-916, and against a synthetic peptide representing the major glutamate rich repeat sequence from the P. falciparum ring erythrocyte surface antigen (Pf155...... between the anti-GLURP489-1271 and anti-(EENV)6 antibody responses. The data provide indirect evidence for a protective role of antibodies reacting with recombinant GLURP489-1271 as well as with the synthetic peptide (EENV)6 from the Pf155/RESA....

  1. Naturally acquired immunity to Plasmodium falciparum malaria in Africa

    DEFF Research Database (Denmark)

    Hviid, Lars

    2005-01-01

    Infection by Plasmodium falciparum parasites can lead to substantial protective immunity to malaria, and available evidence suggest that acquisition of protection against some severe malaria syndromes can be fairly rapid. Although these facts have raised hopes that the development of effective...... vaccines against this major cause of human misery is a realistic goal, the uncertainty regarding the antigenic targets of naturally acquired protective immunity and the immunological mechanisms involved remain major vaccine development obstacles. Nevertheless, a coherent theoretical framework of how...... protective immunity to P. falciparum malaria is acquired following natural exposure to the parasites is beginning to emerge, not least thanks to studies that have combined clinical and epidemiological data with basic immunological research. This framework involves IgG with specificity for clonally variant...

  2. Exploring Drug Targets in Isoprenoid Biosynthetic Pathway for Plasmodium falciparum

    Directory of Open Access Journals (Sweden)

    Tabish Qidwai

    2014-01-01

    Full Text Available Emergence of rapid drug resistance to existing antimalarial drugs in Plasmodium falciparum has created the need for prediction of novel targets as well as leads derived from original molecules with improved activity against a validated drug target. The malaria parasite has a plant plastid-like apicoplast. To overcome the problem of falciparum malaria, the metabolic pathways in parasite apicoplast have been used as antimalarial drug targets. Among several pathways in apicoplast, isoprenoid biosynthesis is one of the important pathways for parasite as its multiplication in human erythrocytes requires isoprenoids. Therefore targeting this pathway and exploring leads with improved activity is a highly attractive approach. This report has explored progress towards the study of proteins and inhibitors of isoprenoid biosynthesis pathway. For more comprehensive analysis, antimalarial drug-protein interaction has been covered.

  3. Engineered resistance to Plasmodium falciparum development in transgenic Anopheles stephensi.

    Directory of Open Access Journals (Sweden)

    Alison T Isaacs

    2011-04-01

    Full Text Available Transposon-mediated transformation was used to produce Anopheles stephensi that express single-chain antibodies (scFvs designed to target the human malaria parasite, Plasmodium falciparum. The scFvs, m1C3, m4B7, and m2A10, are derived from mouse monoclonal antibodies that inhibit either ookinete invasion of the midgut or sporozoite invasion of salivary glands. The scFvs that target the parasite surface, m4B7 and m2A10, were fused to an Anopheles gambiae antimicrobial peptide, Cecropin A. Previously-characterized Anopheles cis-acting DNA regulatory elements were included in the transgenes to coordinate scFv production with parasite development. Gene amplification and immunoblot analyses showed promoter-specific increases in transgene expression in blood-fed females. Transgenic mosquito lines expressing each of the scFv genes had significantly lower infection levels than controls when challenged with P. falciparum.

  4. Complement activation in Ghanaian children with severe Plasmodium falciparum malaria

    DEFF Research Database (Denmark)

    Helegbe, Gideon K; Goka, Bamenla Q; Kurtzhals, Jørgen

    2007-01-01

    BACKGROUND: Severe anaemia (SA), intravascular haemolysis (IVH) and respiratory distress (RD) are severe forms of Plasmodium falciparum malaria, with RD reported to be of prognostic importance in African children with malarial anaemia. Complement factors have been implicated in the mechanism......55)] in children with discrete clinical forms of P. falciparum malaria. The relationship between the findings and clinical parameters including coma, haemoglobin (Hb) levels and RD were investigated. RESULTS: Of the 484 samples tested, 131(27%) were positive in DCT, out of which 115/131 (87.8%) were...... malaria, possibly through induction of erythrophagocytosis and haemolysis. In contrast to other studies, this study did not find association between levels of the complement...

  5. Plasmodium falciparum malariometric indices in Apac district, northern Uganda.

    Science.gov (United States)

    Egwang, T G; Apio, B; Riley, E; Okello, D

    2000-08-01

    To establish Plasmodium falciparum malariometric indices in a field study site in Apac district, northern Uganda. A community-based cross sectional survey. Atopi Parish, Apac district, Uganda, 1995. One thousand two hundred and thirty four volunteers aged below one and ninety years. P. falciparum parasitaemia rates and parasite density, splenomegaly, bednet use and chloroquine consumption. All subjects with P. falciparum positive smears were treated with chloroquine. The population prevalence of parasitaemia was 62.1% with the predominant species being P. falciparum (100%) and P. malariae in the minority (3.5%); P. ovale was not seen. The prevalence of parasitaemia in subjects older than 20 years and in those under ten years was 36% and 85%, respectively. The geometric mean parasite density started to decline by the age of six years. The splenomegaly rate in subjects over the age of 12 years and in those under nine years was 19.8% and 63.1%, respectively. Bednet use and chloroquine consumption was low. Interestingly, the reported use of chloroquine in the week immediately preceding the study was more frequent in children under two years old than in the rest of the population. Malaria transmission in Atopi Parish in northern Uganda is hyperendemic and age-related acquired anti-parasite immunity seems to appear by seven years of age.

  6. Plasmodium falciparum drug resistance in Angola.

    Science.gov (United States)

    Fançony, Cláudia; Brito, Miguel; Gil, Jose Pedro

    2016-02-09

    Facing chloroquine drug resistance, Angola promptly adopted artemisinin-based combination therapy as the first-line to treat malaria. Currently, the country aims to consolidate malaria control, while preparing for the elimination of the disease, along with others African countries in the region. However, the remarkable capacity of Plasmodium to develop drug resistance represents an alarming threat for those achievements. Herein, the available, but relatively scarce and dispersed, information on malaria drug resistance in Angola, is reviewed and discussed. The review aims to inform but also to encourage future research studies that monitor and update the information on anti-malarial drug efficacy and prevalence of molecular markers of drug resistance, key fields in the context and objectives of elimination.

  7. Caspar controls resistance to Plasmodium falciparum in diverse anopheline species.

    Directory of Open Access Journals (Sweden)

    Lindsey S Garver

    2009-03-01

    Full Text Available Immune responses mounted by the malaria vector Anopheles gambiae are largely regulated by the Toll and Imd (immune deficiency pathways via the NF-kappaB transcription factors Rel1 and Rel2, which are controlled by the negative regulators Cactus and Caspar, respectively. Rel1- and Rel2-dependent transcription in A. gambiae has been shown to be particularly critical to the mosquito's ability to manage infection with the rodent malaria parasite Plasmodium berghei. Using RNA interference to deplete the negative regulators of these pathways, we found that Rel2 controls resistance of A. gambiae to the human malaria parasite Plasmodium falciparum, whereas Rel 1 activation reduced infection levels. The universal relevance of this defense system across Anopheles species was established by showing that caspar silencing also prevents the development of P. falciparum in the major malaria vectors of Asia and South America, A. stephensi and A. albimanus, respectively. Parallel studies suggest that while Imd pathway activation is most effective against P. falciparum, the Toll pathway is most efficient against P. berghei, highlighting a significant discrepancy between the human pathogen and its rodent model. High throughput gene expression analyses identified a plethora of genes regulated by the activation of the two Rel factors and revealed that the Toll pathway played a more diverse role in mosquito biology than the Imd pathway, which was more immunity-specific. Further analyses of key anti-Plasmodium factors suggest they may be responsible for the Imd pathway-mediated resistance phenotype. Additionally, we found that the fitness cost caused by Rel2 activation through caspar gene silencing was undetectable in sugar-fed, blood-fed, and P. falciparum-infected female A. gambiae, while activation of the Toll pathway's Rel1 had a major impact. This study describes for the first time a single gene that influences an immune mechanism that is able to abort

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

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    Imrie Heather J

    2008-01-01

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

  9. Molecular epidemiology of drug-resistant Plasmodium falciparum in Benguela province, Angola.

    Science.gov (United States)

    Foumane Ngane, Vincent; Allico Djaman, Joseph; Culeux, Cécile; Piette, Nathalie; Carnevale, Pierre; Besnard, Patrick; Fortes, Filomeno; Basco, Leonardo K; Tahar, Rachida

    2015-03-14

    The malaria situation has been worsening in Angola, partly due to armed conflict until the recent past and drug-resistant Plasmodium falciparum. Malaria transmission is heterogeneous within the country, and data on drug-resistant malaria in different parts of the country are incomplete. The aim of the present study was to evaluate resistance to 4-aminoquinolines and antifolate drugs in P. falciparum isolates collected in Benguela province, central Angola, using molecular markers. Fingerprick capillary blood was collected from asymptomatic children aged less than 15 years old during a household survey in and around Balombo town in 2010-2011. Samples were screened for P. falciparum by nested PCR. Molecular markers (P. falciparum dihydrofolate reductase [pfdhfr], P. falciparum dihydropteroate synthase [pfdhps], P. falciparum chloroquine resistance transporter [pfcrt], and P. falciparum multidrug-resistance gene 1 [pfmdr1]) were sequenced to determine the key codons associated with drug resistance. A total of 60 blood samples were positive for P. falciparum. Most isolates with successful PCR amplification had mutant pfdhfr alleles, with either double mutant AICNI (69%) or triple mutant AIRNI (21%) haplotypes. A16V, S108T, and I164L substitutions were not found. Many of the isolates were carriers of either SGKAA (60%) or AGKAA (27%) pfdhps haplotype. K540E substitution was absent. There were only two pfcrt haplotypes: wild-type CVMNK (11%) and mutant CVIET (89%). Wild-type pfmdr1 NYSND haplotype was found in 19% of the isolates, whereas single mutant pfmdr1 YYSND and NFSND haplotypes occurred in 48% and 11%, respectively. Double mutant pfmdr1 haplotypes (YFSND and YYSNY) occurred rarely. The results suggest that the high prevalence of mutant pfcrt CVIET haplotype is in agreement with low clinical efficacy of chloroquine observed in earlier studies and that the double pfdhfr mutant AICNI and single pfdhps mutant SGKAA are currently the predominant haplotypes associated

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

    OpenAIRE

    Barber Bridget E; William Timothy; Grigg Matthew J; Yeo Tsin W; Anstey Nicholas M

    2013-01-01

    Abstract 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 perfor...

  11. Intrarectal quinine for treating Plasmodium falciparum malaria: a systematic review

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    Omari Aika

    2005-05-01

    Full Text Available Abstract Background In children with malaria caused by Plasmodium falciparum, quinine administered rectally may be easier to use and less painful than intramuscular or intravenous administration. The objective of this review was to compare the effectiveness of intrarectal with intravenous or intramuscular quinine for treating falciparum malaria. Methods All randomized and quasi-randomized controlled trials comparing intrarectal with intramuscular or intravenous quinine for treating people with falciparum malaria located through the following sources were included: Cochrane Infectious Diseases Group Specialized Register, CENTRAL, MEDLINE, EMBASE, LILACS and CINAHL. Trial quality was assessed and data, including adverse event data, were extracted. Dichotomous data were analysed using odds ratios and continuous data using weighted mean difference. Results Eight randomized controlled trials (1,247 children fulfilled the inclusion criteria. The same principal investigator led seven of the trials. Five compared intrarectal with intravenous quinine, and six compared intrarectal with intramuscular treatment. No statistically significant difference was detected for death, parasite clearance by 48 hours and seven days, parasite and fever clearance time, coma recovery time, duration of hospitalization and time before drinking began. One trial (898 children reported that intrarectal was less painful than intramuscular administration. Conclusion No difference in the effect on parasites and clinical illness was detected for the use of intrarectal quinine compared with other routes, but most trials were small. Pain during application may be less with intrarectal quinine. Further larger trials, in patients with severe malaria and in adults, are required before the intrarectal route could be recommended.

  12. Targeting NAD+ metabolism in the human malaria parasite Plasmodium falciparum.

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    Jessica K O'Hara

    Full Text Available Nicotinamide adenine dinucleotide (NAD+ is an essential metabolite utilized as a redox cofactor and enzyme substrate in numerous cellular processes. Elevated NAD+ levels have been observed in red blood cells infected with the malaria parasite Plasmodium falciparum, but little is known regarding how the parasite generates NAD+. Here, we employed a mass spectrometry-based metabolomic approach to confirm that P. falciparum lacks the ability to synthesize NAD+ de novo and is reliant on the uptake of exogenous niacin. We characterized several enzymes in the NAD+ pathway and demonstrate cytoplasmic localization for all except the parasite nicotinamidase, which concentrates in the nucleus. One of these enzymes, the P. falciparum nicotinate mononucleotide adenylyltransferase (PfNMNAT, is essential for NAD+ metabolism and is highly diverged from the human homolog, but genetically similar to bacterial NMNATs. Our results demonstrate the enzymatic activity of PfNMNAT in vitro and demonstrate its ability to genetically complement the closely related Escherichia coli NMNAT. Due to the similarity of PfNMNAT to the bacterial enzyme, we tested a panel of previously identified bacterial NMNAT inhibitors and synthesized and screened twenty new derivatives, which demonstrate a range of potency against live parasite culture. These results highlight the importance of the parasite NAD+ metabolic pathway and provide both novel therapeutic targets and promising lead antimalarial compounds.

  13. Laboratory detection of artemisinin-resistant Plasmodium falciparum.

    Science.gov (United States)

    Chotivanich, Kesinee; Tripura, Rupam; Das, Debashish; Yi, Poravuth; Day, Nicholas P J; Pukrittayakamee, Sasithon; Chuor, Char Meng; Socheat, Duong; Dondorp, Arjen M; White, Nicholas J

    2014-06-01

    Conventional 48-h in vitro susceptibility tests have low sensitivity in identifying artemisinin-resistant Plasmodium falciparum, defined phenotypically by low in vivo parasite clearance rates. We hypothesized originally that this discrepancy was explained by a loss of ring-stage susceptibility and so developed a simple field-adapted 24-h trophozoite maturation inhibition (TMI) assay focusing on the ring stage and compared it to the standard 48-h schizont maturation inhibition (WHO) test. In Pailin, western Cambodia, where artemisinin-resistant P. falciparum is prevalent, the TMI test mean (95% confidence interval) 50% inhibitory concentration (IC50) for artesunate was 6.8 (5.2 to 8.3) ng/ml compared with 1.5 (1.2 to 1.8) ng/ml for the standard 48-h WHO test (P = 0.001). TMI IC50s correlated significantly with the in vivo responses to artesunate (parasite clearance time [r = 0.44, P = 0.001] and parasite clearance half-life [r = 0.46, P = 0.001]), whereas the standard 48-h test values did not. On continuous culture of two resistant isolates, the artemisinin-resistant phenotype was lost after 6 weeks (IC50s fell from 10 and 12 ng/ml to 2.7 and 3 ng/ml, respectively). Slow parasite clearance in falciparum malaria in western Cambodia results from reduced ring-stage susceptibility. Copyright © 2014 Chotivanich et al.

  14. Human genetic variation is associated with Plasmodium falciparum drug resistance.

    Science.gov (United States)

    Paganotti, Giacomo M; Gallo, Baba C; Verra, Federica; Sirima, Bienvenu S; Nebié, Issa; Diarra, Amidou; Coluzzi, Mario; Modiano, David

    2011-12-01

    One approach to investigate if human genetic variation influences the selection of Plasmodium falciparum drug resistance is to compare the frequency of resistant infections among human populations differing in their genetic background and living in the same epidemiological context. A further complementary approach consists in comparing drug resistance among subjects differing for genes involved in drug metabolism. Here we report, from malariological surveys performed in Burkina Faso, that the prevalence of P. falciparum chloroquine-resistant infections (pfcrt 76T and/or pfmdr1 86Y alleles) differs among sympatric ethnic groups, being higher in the Mossi and Rimaibé groups than in the Fulani group (odds ratio [OR], 2.24; 95% confidence interval [CI], 1.27-3.92; P = .007). The association analysis revealed that the human CYP2C8*2 variant, known to determine a poor drug metabolizer phenotype, was associated with P. falciparum chloroquine-resistant infections (OR, 1.66; 95% CI, 1.13-2.43; P = .008). This variant is more frequent in the Mossi-Rimaibé group (23.7% ± 1.4%) than in the Fulani group (9.9% ± 2.5%; P = .0003). This study provides an example of how host genetic variation may influence the selection dynamics of a pathogen's drug resistance.

  15. Capture ELISA for IgM antibodies against Plasmodium falciparum glutamate rich protein

    DEFF Research Database (Denmark)

    Dziegiel, Morten Hanefeld; Borre, M B; Petersen, E

    1992-01-01

    This report describes a novel mu chain capture ELISA for the detection of IgM antibodies against a Plasmodium falciparum antigen. A fragment of the 220 kDa P. falciparum glutamate rich protein containing amino acid residues 489-1271 was expressed in E. coli as a recombinant chimeric beta-galactos......This report describes a novel mu chain capture ELISA for the detection of IgM antibodies against a Plasmodium falciparum antigen. A fragment of the 220 kDa P. falciparum glutamate rich protein containing amino acid residues 489-1271 was expressed in E. coli as a recombinant chimeric beta...

  16. Modelling the Incidence of Plasmodium vivax and Plasmodium falciparum Malaria in Afghanistan 2006–2009

    Science.gov (United States)

    Alegana, Victor A.; Wright, Jim A.; Nahzat, Sami M.; Butt, Waqar; Sediqi, Amad W.; Habib, Naeem; Snow, Robert W.; Atkinson, Peter M.; Noor, Abdisalan M.

    2014-01-01

    Background Identifying areas that support high malaria risks and where populations lack access to health care is central to reducing the burden in Afghanistan. This study investigated the incidence of Plasmodium vivax and Plasmodium falciparum using routine data to help focus malaria interventions. Methods To estimate incidence, the study modelled utilisation of the public health sector using fever treatment data from the 2012 national Malaria Indicator Survey. A probabilistic measure of attendance was applied to population density metrics to define the proportion of the population within catchment of a public health facility. Malaria data were used in a Bayesian spatio-temporal conditional-autoregressive model with ecological or environmental covariates, to examine the spatial and temporal variation of incidence. Findings From the analysis of healthcare utilisation, over 80% of the population was within 2 hours’ travel of the nearest public health facility, while 64.4% were within 30 minutes’ travel. The mean incidence of P. vivax in 2009 was 5.4 (95% Crl 3.2–9.2) cases per 1000 population compared to 1.2 (95% Crl 0.4–2.9) cases per 1000 population for P. falciparum. P. vivax peaked in August while P. falciparum peaked in November. 32% of the estimated 30.5 million people lived in regions where annual incidence was at least 1 case per 1,000 population of P. vivax; 23.7% of the population lived in areas where annual P. falciparum case incidence was at least 1 per 1000. Conclusion This study showed how routine data can be combined with household survey data to model malaria incidence. The incidence of both P. vivax and P. falciparum in Afghanistan remain low but the co-distribution of both parasites and the lag in their peak season provides challenges to malaria control in Afghanistan. Future improved case definition to determine levels of imported risks may be useful for the elimination ambitions in Afghanistan. PMID:25033452

  17. Modelling the incidence of Plasmodium vivax and Plasmodium falciparum malaria in Afghanistan 2006-2009.

    Science.gov (United States)

    Alegana, Victor A; Wright, Jim A; Nahzat, Sami M; Butt, Waqar; Sediqi, Amad W; Habib, Naeem; Snow, Robert W; Atkinson, Peter M; Noor, Abdisalan M

    2014-01-01

    Identifying areas that support high malaria risks and where populations lack access to health care is central to reducing the burden in Afghanistan. This study investigated the incidence of Plasmodium vivax and Plasmodium falciparum using routine data to help focus malaria interventions. To estimate incidence, the study modelled utilisation of the public health sector using fever treatment data from the 2012 national Malaria Indicator Survey. A probabilistic measure of attendance was applied to population density metrics to define the proportion of the population within catchment of a public health facility. Malaria data were used in a Bayesian spatio-temporal conditional-autoregressive model with ecological or environmental covariates, to examine the spatial and temporal variation of incidence. From the analysis of healthcare utilisation, over 80% of the population was within 2 hours' travel of the nearest public health facility, while 64.4% were within 30 minutes' travel. The mean incidence of P. vivax in 2009 was 5.4 (95% Crl 3.2-9.2) cases per 1000 population compared to 1.2 (95% Crl 0.4-2.9) cases per 1000 population for P. falciparum. P. vivax peaked in August while P. falciparum peaked in November. 32% of the estimated 30.5 million people lived in regions where annual incidence was at least 1 case per 1,000 population of P. vivax; 23.7% of the population lived in areas where annual P. falciparum case incidence was at least 1 per 1000. This study showed how routine data can be combined with household survey data to model malaria incidence. The incidence of both P. vivax and P. falciparum in Afghanistan remain low but the co-distribution of both parasites and the lag in their peak season provides challenges to malaria control in Afghanistan. Future improved case definition to determine levels of imported risks may be useful for the elimination ambitions in Afghanistan.

  18. Role and Regulation of Glutathione Metabolism in Plasmodium falciparum

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    Sylke Müller

    2015-06-01

    Full Text Available Malaria in humans is caused by one of five species of obligate intracellular protozoan parasites of the genus Plasmodium. P. falciparum causes the most severe disease and is responsible for 600,000 deaths annually, primarily in Sub-Saharan Africa. It has long been suggested that during their development, malaria parasites are exposed to environmental and metabolic stresses. One strategy to drug discovery was to increase these stresses by interfering with the parasites’ antioxidant and redox systems, which may be a valuable approach to disease intervention. Plasmodium possesses two redox systems—the thioredoxin and the glutathione system—with overlapping but also distinct functions. Glutathione is the most abundant low molecular weight redox active thiol in the parasites existing primarily in its reduced form representing an excellent thiol redox buffer. This allows for an efficient maintenance of the intracellular reducing environment of the parasite cytoplasm and its organelles. This review will highlight the mechanisms that are responsible for sustaining an adequate concentration of glutathione and maintaining its redox state in Plasmodium. It will provide a summary of the functions of the tripeptide and will discuss the potential of glutathione metabolism for drug discovery against human malaria parasites.

  19. Induction of Plasmodium falciparum strain 2300 dormant forms by artemisinin

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    Lilik Maslachah

    2015-04-01

    Full Text Available Background The presence of Plasmodium falciparum resistance and decreased efficacy of artemisinin and its derivatives has resulted in the issue of malaria becoming increasingly complex, because there have been no new drugs as artemisinin replacements. The aims of this research were to evaluate in vitro changes in ultrastructural morphology of P. falciparum 2300 strain after exposure to artemisinin. Methods The research used an experimental design with post test only control group. Cultures of P. falciparum 2300 strain in one control and one mutant group were treated by exposure to artemisinin at IC50 10-7 M for 48 hours. Ultrastructural phenotypic examination of ring, trophozoite and schizont morphology and developmental stage in the control and mutant group were done at 0, 12, 24, 36, 48 hours by making thin blood smears stained with 20% Giemsa for 20 minutes and examined using a microscope light at 1000x magnification. Results Dormant forms occurred after 48 hours of incubation with IC50 10-7 M artemisinin in the control group. In the mutant group, dormant forms, trophozoites with blue cytoplasm and normal schizont developmental stages were seen. Ultrastructural phenotypic morphology at 0, 12, 24, 36, 48 hours showed that in the control group dormant formation already occurred with exposure to IC50 10-7 M, while in the mutant group dormant formation occurred only with exposure to IC50 2.5x10-5 M. Conclusion Exposure to artemisinin antimalarials in vitro can cause phenotypic morphological changes of dormancy in P. falciparum Papua 2300 strain.

  20. Induction of Plasmodium falciparum strain 2300 dormant forms by artemisinin

    Directory of Open Access Journals (Sweden)

    Lilik Maslachah

    2016-02-01

    Full Text Available BACKGROUND The presence of Plasmodium falciparum resistance and decreased efficacy of artemisinin and its derivatives has resulted in the issue of malaria becoming increasingly complex, because there have been no new drugs as artemisinin replacements. The aims of this research were to evaluate in vitro changes in ultrastructural morphology of P. falciparum 2300 strain after exposure to artemisinin. METHODS The research used an experimental design with post test only control group. Cultures of P. falciparum 2300 strain in one control and one mutant group were treated by exposure to artemisinin at IC50 10-7 M for 48 hours. Ultrastructural phenotypic examination of ring, trophozoite and schizont morphology and developmental stage in the control and mutant group were done at 0, 12, 24, 36, 48 hours by making thin blood smears stained with 20% Giemsa for 20 minutes and examined using a microscope light at 1000x magnification. RESULTS Dormant forms occurred after 48 hours of incubation with IC50 10-7 M artemisinin in the control group. In the mutant group, dormant forms, trophozoites with blue cytoplasm and normal schizont developmental stages were seen. Ultrastructural phenotypic morphology at 0, 12, 24, 36, 48 hours showed that in the control group dormant formation already occurred with exposure to IC50 10-7 M, while in the mutant group dormant formation occurred only with exposure to IC50 2.5x10-5 M. CONCLUSION Exposure to artemisinin antimalarials in vitro can cause phenotypic morphological changes of dormancy in P. falciparum Papua 2300 strain.

  1. Heterologous Protection against Malaria after Immunization with Plasmodium falciparum Sporozoites.

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    Remko Schats

    Full Text Available Sterile protection in >90% of volunteers against homologous Plasmodium falciparum infection has been achieved only using the controlled human malaria infection (CHMI model. This efficient model involves whole parasite immunizations under chloroquine prophylaxis (CPS-immunization, requiring only 30-45 mosquitoes bites infected with P. falciparum-sporozoites. Given the large diversity of P. falciparum parasites, it is essential to assess protection against heterologous parasite strains.In an open-label follow-up study, 16 volunteers previously CPS-immunized and challenged with P. falciparum NF54 (West-Africa in a dose de-escalation and challenge trial were re-challenged with clone NF135.C10 (Cambodia at 14 months after the last immunization (NCT01660854.Two out of thirteen NF54 protected volunteers previously fully protected against NF54 were also fully protected against NF135.C10, while 11/13 showed a delayed patency (median prepatent period of 10.5 days (range 9.0-15.5 versus 8.5 days in 5 malaria-naïve controls (p = 0.0005. Analysis of patency by qPCR indicated a 91 to >99% estimated reduction of liver parasite load in 7/11 partially protected subjects. Three volunteers previously not protected against NF54, were also not protected against NF135.C10.This study shows that CPS-immunization can induce heterologous protection for a period of more than one year, which is a further impetus for clinical development of whole parasite vaccines.Clinicaltrials.gov NCT01660854.

  2. Complement activation in Ghanaian children with severe Plasmodium falciparum malaria

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    Ofori Michael F

    2007-12-01

    Full Text Available Abstract Background Severe anaemia (SA, intravascular haemolysis (IVH and respiratory distress (RD are severe forms of Plasmodium falciparum malaria, with RD reported to be of prognostic importance in African children with malarial anaemia. Complement factors have been implicated in the mechanism leading to excess anaemia in acute P. falciparum infection. Methods The direct Coombs test (DCT and flow cytometry were used to investigate the mean levels of RBC-bound complement fragments (C3d and C3bαβ and the regulatory proteins [complement receptor 1 (CD35 and decay accelerating factor (CD55] in children with discrete clinical forms of P. falciparum malaria. The relationship between the findings and clinical parameters including coma, haemoglobin (Hb levels and RD were investigated. Results Of the 484 samples tested, 131(27% were positive in DCT, out of which 115/131 (87.8% were positive for C3d alone while 16/131 (12.2% were positive for either IgG alone or both. 67.4% of the study population were below 5 years of age and DCT positivity was more common in this age group relative to children who were 5 years or older (Odds ratio, OR = 3.8; 95%CI, 2.2–6.7, p Conclusion These results suggest that complement activation contributed to anaemia in acute childhood P. falciparum malaria, possibly through induction of erythrophagocytosis and haemolysis. In contrast to other studies, this study did not find association between levels of the complement regulatory proteins, CD35 and CD55 and malarial anaemia. These findings suggest that complement activation could also be involved in the pathogenesis of RD but larger studies are needed to confirm this finding.

  3. Reduced susceptibility of Plasmodium falciparum to artesunate in southern Myanmar.

    Science.gov (United States)

    Kyaw, Myat P; Nyunt, Myat H; Chit, Khin; Aye, Moe M; Aye, Kyin H; Aye, Moe M; Lindegardh, Niklas; Tarning, Joel; Imwong, Mallika; Jacob, Christopher G; Rasmussen, Charlotte; Perin, Jamie; Ringwald, Pascal; Nyunt, Myaing M

    2013-01-01

    Plasmodium falciparum resistance to artemisinins, the first line treatment for malaria worldwide, has been reported in western Cambodia. Resistance is characterized by significantly delayed clearance of parasites following artemisinin treatment. Artemisinin resistance has not previously been reported in Myanmar, which has the highest falciparum malaria burden among Southeast Asian countries. A non-randomized, single-arm, open-label clinical trial of artesunate monotherapy (4 mg/kg daily for seven days) was conducted in adults with acute blood-smear positive P. falciparum malaria in Kawthaung, southern Myanmar. Parasite density was measured every 12 hours until two consecutive negative smears were obtained. Participants were followed weekly at the study clinic for three additional weeks. Co-primary endpoints included parasite clearance time (the time required for complete clearance of initial parasitemia), parasite clearance half-life (the time required for parasitemia to decrease by 50% based on the linear portion of the parasite clearance slope), and detectable parasitemia 72 hours after commencement of artesunate treatment. Drug pharmacokinetics were measured to rule out delayed clearance due to suboptimal drug levels. The median (range) parasite clearance half-life and time were 4.8 (2.1-9.7) and 60 (24-96) hours, respectively. The frequency distributions of parasite clearance half-life and time were bimodal, with very slow parasite clearance characteristic of the slowest-clearing Cambodian parasites (half-life longer than 6.2 hours) in approximately 1/3 of infections. Fourteen of 52 participants (26.9%) had a measurable parasitemia 72 hours after initiating artesunate treatment. Parasite clearance was not associated with drug pharmacokinetics. A subset of P. falciparum infections in southern Myanmar displayed markedly delayed clearance following artemisinin treatment, suggesting either emergence of artemisinin resistance in southern Myanmar or spread to this

  4. Reduced susceptibility of Plasmodium falciparum to artesunate in southern Myanmar.

    Directory of Open Access Journals (Sweden)

    Myat P Kyaw

    Full Text Available Plasmodium falciparum resistance to artemisinins, the first line treatment for malaria worldwide, has been reported in western Cambodia. Resistance is characterized by significantly delayed clearance of parasites following artemisinin treatment. Artemisinin resistance has not previously been reported in Myanmar, which has the highest falciparum malaria burden among Southeast Asian countries.A non-randomized, single-arm, open-label clinical trial of artesunate monotherapy (4 mg/kg daily for seven days was conducted in adults with acute blood-smear positive P. falciparum malaria in Kawthaung, southern Myanmar. Parasite density was measured every 12 hours until two consecutive negative smears were obtained. Participants were followed weekly at the study clinic for three additional weeks. Co-primary endpoints included parasite clearance time (the time required for complete clearance of initial parasitemia, parasite clearance half-life (the time required for parasitemia to decrease by 50% based on the linear portion of the parasite clearance slope, and detectable parasitemia 72 hours after commencement of artesunate treatment. Drug pharmacokinetics were measured to rule out delayed clearance due to suboptimal drug levels.The median (range parasite clearance half-life and time were 4.8 (2.1-9.7 and 60 (24-96 hours, respectively. The frequency distributions of parasite clearance half-life and time were bimodal, with very slow parasite clearance characteristic of the slowest-clearing Cambodian parasites (half-life longer than 6.2 hours in approximately 1/3 of infections. Fourteen of 52 participants (26.9% had a measurable parasitemia 72 hours after initiating artesunate treatment. Parasite clearance was not associated with drug pharmacokinetics.A subset of P. falciparum infections in southern Myanmar displayed markedly delayed clearance following artemisinin treatment, suggesting either emergence of artemisinin resistance in southern Myanmar or spread

  5. Spread of artemisinin resistance in Plasmodium falciparum malaria.

    Science.gov (United States)

    Ashley, Elizabeth A; Dhorda, Mehul; Fairhurst, Rick M; Amaratunga, Chanaki; Lim, Parath; Suon, Seila; Sreng, Sokunthea; Anderson, Jennifer M; Mao, Sivanna; Sam, Baramey; Sopha, Chantha; Chuor, Char Meng; Nguon, Chea; Sovannaroth, Siv; Pukrittayakamee, Sasithon; Jittamala, Podjanee; Chotivanich, Kesinee; Chutasmit, Kitipumi; Suchatsoonthorn, Chaiyaporn; Runcharoen, Ratchadaporn; Hien, Tran Tinh; Thuy-Nhien, Nguyen Thanh; Thanh, Ngo Viet; Phu, Nguyen Hoan; Htut, Ye; Han, Kay-Thwe; Aye, Kyin Hla; Mokuolu, Olugbenga A; Olaosebikan, Rasaq R; Folaranmi, Olaleke O; Mayxay, Mayfong; Khanthavong, Maniphone; Hongvanthong, Bouasy; Newton, Paul N; Onyamboko, Marie A; Fanello, Caterina I; Tshefu, Antoinette K; Mishra, Neelima; Valecha, Neena; Phyo, Aung Pyae; Nosten, Francois; Yi, Poravuth; Tripura, Rupam; Borrmann, Steffen; Bashraheil, Mahfudh; Peshu, Judy; Faiz, M Abul; Ghose, Aniruddha; Hossain, M Amir; Samad, Rasheda; Rahman, M Ridwanur; Hasan, M Mahtabuddin; Islam, Akhterul; Miotto, Olivo; Amato, Roberto; MacInnis, Bronwyn; Stalker, Jim; Kwiatkowski, Dominic P; Bozdech, Zbynek; Jeeyapant, Atthanee; Cheah, Phaik Yeong; Sakulthaew, Tharisara; Chalk, Jeremy; Intharabut, Benjamas; Silamut, Kamolrat; Lee, Sue J; Vihokhern, Benchawan; Kunasol, Chanon; Imwong, Mallika; Tarning, Joel; Taylor, Walter J; Yeung, Shunmay; Woodrow, Charles J; Flegg, Jennifer A; Das, Debashish; Smith, Jeffery; Venkatesan, Meera; Plowe, Christopher V; Stepniewska, Kasia; Guerin, Philippe J; Dondorp, Arjen M; Day, Nicholas P; White, Nicholas J

    2014-07-31

    Artemisinin resistance in Plasmodium falciparum has emerged in Southeast Asia and now poses a threat to the control and elimination of malaria. Mapping the geographic extent of resistance is essential for planning containment and elimination strategies. Between May 2011 and April 2013, we enrolled 1241 adults and children with acute, uncomplicated falciparum malaria in an open-label trial at 15 sites in 10 countries (7 in Asia and 3 in Africa). Patients received artesunate, administered orally at a daily dose of either 2 mg per kilogram of body weight per day or 4 mg per kilogram, for 3 days, followed by a standard 3-day course of artemisinin-based combination therapy. Parasite counts in peripheral-blood samples were measured every 6 hours, and the parasite clearance half-lives were determined. The median parasite clearance half-lives ranged from 1.9 hours in the Democratic Republic of Congo to 7.0 hours at the Thailand-Cambodia border. Slowly clearing infections (parasite clearance half-life >5 hours), strongly associated with single point mutations in the "propeller" region of the P. falciparum kelch protein gene on chromosome 13 (kelch13), were detected throughout mainland Southeast Asia from southern Vietnam to central Myanmar. The incidence of pretreatment and post-treatment gametocytemia was higher among patients with slow parasite clearance, suggesting greater potential for transmission. In western Cambodia, where artemisinin-based combination therapies are failing, the 6-day course of antimalarial therapy was associated with a cure rate of 97.7% (95% confidence interval, 90.9 to 99.4) at 42 days. Artemisinin resistance to P. falciparum, which is now prevalent across mainland Southeast Asia, is associated with mutations in kelch13. Prolonged courses of artemisinin-based combination therapies are currently efficacious in areas where standard 3-day treatments are failing. (Funded by the U.K. Department of International Development and others; Clinical

  6. A world malaria map: Plasmodium falciparum endemicity in 2007.

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    Simon I Hay

    2009-03-01

    Full Text Available Efficient allocation of resources to intervene against malaria requires a detailed understanding of the contemporary spatial distribution of malaria risk. It is exactly 40 y since the last global map of malaria endemicity was published. This paper describes the generation of a new world map of Plasmodium falciparum malaria endemicity for the year 2007.A total of 8,938 P. falciparum parasite rate (PfPR surveys were identified using a variety of exhaustive search strategies. Of these, 7,953 passed strict data fidelity tests for inclusion into a global database of PfPR data, age-standardized to 2-10 y for endemicity mapping. A model-based geostatistical procedure was used to create a continuous surface of malaria endemicity within previously defined stable spatial limits of P. falciparum transmission. These procedures were implemented within a Bayesian statistical framework so that the uncertainty of these predictions could be evaluated robustly. The uncertainty was expressed as the probability of predicting correctly one of three endemicity classes; previously stratified to be an informative guide for malaria control. Population at risk estimates, adjusted for the transmission modifying effects of urbanization in Africa, were then derived with reference to human population surfaces in 2007. Of the 1.38 billion people at risk of stable P. falciparum malaria, 0.69 billion were found in Central and South East Asia (CSE Asia, 0.66 billion in Africa, Yemen, and Saudi Arabia (Africa+, and 0.04 billion in the Americas. All those exposed to stable risk in the Americas were in the lowest endemicity class (PfPR2-10 5 to or = 40% areas. High endemicity was widespread in the Africa+ region, where 0.35 billion people are at this level of risk. Most of the rest live at intermediate risk (0.20 billion, with a smaller number (0.11 billion at low stable risk.High levels of P. falciparum malaria endemicity are common in Africa. Uniformly low endemic levels are

  7. Loading of erythrocyte membrane with pentacyclic triterpenes inhibits Plasmodium falciparum invasion

    DEFF Research Database (Denmark)

    Ziegler, Hanne L; Staalsø, Trine; Jaroszewski, Jerzy W

    2006-01-01

    Lupeol and betulinic acid inhibit the proliferation of Plasmodium falciparum parasites by inhibition of the invasion of merozoites into erythrocytes. This conclusion is based on experiments employing parasite cultures synchronized by magnetic cell sorting (MACS). Identical inhibitory effects were...

  8. Drug and Vaccine Evaluation in the Human Aotus Plasmodium Falciparum Model

    National Research Council Canada - National Science Library

    Obaldia

    2002-01-01

    The purpose of this report is to present data on the evaluation of drugs and vaccines in the human malaria/Aotus lemurinus lemurinus monkey model experimentally infected with Plasmodium falciparum or vivax...

  9. Memory B-Cell and Antibody Responses Induced by Plasmodium falciparum Sporozoite Immunization

    NARCIS (Netherlands)

    Nahrendorf, W.; Scholzen, A.; Bijker, E.M.; Teirlinck, A.C.; Bastiaens, G.J.H.; Schats, R.; Hermsen, C.C.; Visser, L.G.; Langhorne, J.; Sauerwein, R.W.

    2014-01-01

    BACKGROUND: Immunization of healthy volunteers during receipt of chemoprophylaxis with Plasmodium falciparum sporozoites (CPS-immunization) induces sterile protection from malaria. Antibody responses have long been known to contribute to naturally acquired immunity against malaria, but their

  10. High prevalence of Plasmodium falciparum pfcrt K76T mutation in ...

    African Journals Online (AJOL)

    Saharan Africa coincides with the distribution of Plasmodium falciparum malaria. Due to prolonged heavy use of chloroquine (CQ) as an antimalarial, drug resistance has developed. Many countries including Tanzania abandoned the use of CQ.

  11. Plasmodium falciparum population dynamics in a cohort of pregnant women in Senegal

    DEFF Research Database (Denmark)

    Guitard, Juliette; Andersen, Pernille; Ermont, Caroline

    2010-01-01

    Background: Pregnant women acquire protective antibodies that cross-react with geographically diverse placental Plasmodium falciparum isolates, suggesting that surface molecules expressed on infected erythrocytes by pregnancy-associated malaria (PAM) parasites have conserved epitopes and, that de...

  12. Global Analysis of Transcript and Protein Levels Across the Plasmodium falciparum Life Cycle

    National Research Council Canada - National Science Library

    LeRoch, Karine G; Johnson, Jeffrey R; Florens, Laurence; Zhou, Yingyao; Santrosyan, Audrey; Grainger, Munira; Yan, S. F; Williamson, Kim C; Holder, Anthony A; Carucci, Daniel J; Yates , III, John R

    2004-01-01

    To investigate the role of post-transcriptional controls in the regulation of protein expression for the malaria parasite, Plasmodium falciparum, we have compared mRNA transcript and protein abundance...

  13. Patterns of Plasmodium vivax and Plasmodium falciparum malaria underscore importance of data collection from private health care facilities in India

    Directory of Open Access Journals (Sweden)

    Novak Robert J

    2009-10-01

    Full Text Available Abstract Background This study describes patterns of falciparum and vivax malaria in a private comprehensive-care, multi-specialty hospital in New Delhi from July 2006 to July 2008. Methods Malarial morbidity by Plasmodium species (Plasmodium falciparum, Plasmodium vivax, or Plasmodium sp. was confirmed using microscopy and antigen tests. The influence of seasonal factors and selected patient demographics on morbidity was evaluated. The proportions of malaria cases caused by P. falciparum at the private facility were compared to data from India's National Vector Borne Disease Control Programme (NVBDCP during the same period for the Delhi region. Results In New Delhi, P. faciparum was the dominant cause of cases requiring treatment in the private hospital during the period examined. The national data reported a smaller proportion of malaria cases caused by P. falciparum in the national capital region than was observed in a private facility within the region. Plasmodium vivax also caused a large proportion of the cases presenting clinically at the private hospital during the summer and monsoon seasons. Conclusion The proportion of P. falciparum malaria cases tends to be greatest during the post-monsoon season while the proportion of P. vivax malaria cases tends to be greatest in the monsoon season. Private hospital data demonstrate an under-reporting of malaria case incidences in the data from India's national surveillance programme during the same period for the national capital region.

  14. In Vitro Infectivity Study of Cryopreserved Irradiated Intraerythrocytic Form of Plasmodium falciparum

    Directory of Open Access Journals (Sweden)

    S. Nurhayati

    2017-12-01

    Full Text Available In control human malaria infection studies using irradiated Plasmodium falciparum, the cell bank of irradiated P. falciparum infected erythrocytes is needed. The cell banking methods represent an obvious way to obtain suitable material for blood stage Plasmodium. In a cell bank development of irradiated Plasmodium infected erythrocytes, the ability to cryopreserve procedure of Plasmodium is important to recover the infectivity of irradiated Plasmodium. This study aims at evaluating the in vitro infectivity of cryopreserved irradiated intra-erythrocytic form  P. falciparum. A protein profile investigation using Sodium Dodecyl Sulfate-Polyacrylamide Gel Electrophoresis (SDS-PAGE of cryopreserved  P. falciparum also conducted in this study to know the cryopreserved effect on the protein of irradiated P. falciparum. Plasmodium falciparum of 3D7 strain in human erythrocytes was maintained in invitro continuous culture. When the percentage of parasites was 10-20%, the culture was harvested and irradiated with gamma rays at a dose of 175 Gy. Irradiated P. falciparum then was mixed with cryopreserved solution and stored in -80 °C for one hour before transferred into liquid nitrogen for 20, 40 and 60 days. After being stored the irradiated P. falciparum was thawed and cultured for 20 days. The percentage of parasitaemia was enumerated by examining Giemsa stained thin blood films prepared for 20 days after initiation of culture. Results showed that storage time significantly (p<0.05 influence the percentage of parasitaemia. The cooling procedure and cryopreservation media may affect this study results. It also showed that there was insignificant difference of  P. falciparum protein profile in all storage times. Overall it can be assumed that the irradiated P. falciparum still kept their infectivity after stored in liquid nitrogen for 60 days. Further study using different cooling procedure and different formula of cryopreservation media with a

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

    Science.gov (United States)

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

    2016-12-01

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

  16. Multiple populations of artemisinin-resistant Plasmodium falciparum in Cambodia

    Science.gov (United States)

    Miotto, Olivo; Almagro-Garcia, Jacob; Manske, Magnus; MacInnis, Bronwyn; Campino, Susana; Rockett, Kirk A; Amaratunga, Chanaki; Lim, Pharath; Suon, Seila; Sreng, Sokunthea; Anderson, Jennifer M; Duong, Socheat; Nguon, Chea; Chuor, Char Meng; Saunders, David; Se, Youry; Lon, Chantap; Fukuda, Mark M; Amenga-Etego, Lucas; Hodgson, Abraham VO; Asoala, Victor; Imwong, Mallika; Takala-Harrison, Shannon; Nosten, Francois; Su, Xin-zhuan; Ringwald, Pascal; Ariey, Frédéric; Dolecek, Christiane; Hien, Tran Tinh; Boni, Maciej F; Thai, Cao Quang; Amambua-Ngwa, Alfred; Conway, David J; Djimdé, Abdoulaye A; Doumbo, Ogobara K; Zongo, Issaka; Ouedraogo, Jean-Bosco; Alcock, Daniel; Drury, Eleanor; Auburn, Sarah; Koch, Oliver; Sanders, Mandy; Hubbart, Christina; Maslen, Gareth; Ruano-Rubio, Valentin; Jyothi, Dushyanth; Miles, Alistair; O’Brien, John; Gamble, Chris; Oyola, Samuel O; Rayner, Julian C; Newbold, Chris I; Berriman, Matthew; Spencer, Chris CA; McVean, Gilean; Day, Nicholas P; White, Nicholas J; Bethell, Delia; Dondorp, Arjen M; Plowe, Christopher V; Fairhurst, Rick M; Kwiatkowski, Dominic P

    2013-01-01

    We describe an analysis of genome variation in 825 Plasmodium falciparum samples from Asia and Africa that reveals an unusual pattern of parasite population structure at the epicentre of artemisinin resistance in western Cambodia. Within this relatively small geographical area we have discovered several distinct but apparently sympatric parasite subpopulations with extremely high levels of genetic differentiation. Of particular interest are three subpopulations, all associated with clinical resistance to artemisinin, which have skewed allele frequency spectra and remarkably high levels of haplotype homozygosity, indicative of founder effects and recent population expansion. We provide a catalogue of SNPs that show high levels of differentiation in the artemisinin-resistant subpopulations, including codon variants in various transporter proteins and DNA mismatch repair proteins. These data provide a population genetic framework for investigating the biological origins of artemisinin resistance and for defining molecular markers to assist its elimination. PMID:23624527

  17. An experimental vaccine cocktail for Plasmodium falciparum malaria.

    Science.gov (United States)

    Bathurst, I C; Gibson, H L; Kansopon, J; Hahm, B K; Green, K M; Chang, S P; Hui, G S; Siddiqui, W A; Inselburg, J; Millet, P

    1993-01-01

    Surface proteins from several different life-cycle stages of the malaria parasite Plasmodium falciparum were expressed at high levels in the yeast Saccharomyces cerevisiae. Purified proteins, both individually and in cocktails, were used to immunize mice and goats in conjunction with either Freund's adjuvant or a muramyl tripeptide-based adjuvant. Immune responses were measured by enzyme-linked immunosorbent assays and by the ability of antisera to inhibit (1) the invasion of hepatocytes by live sporozoites, (2) in vitro invasion of human erythrocytes by live merozoites, and (3) the development of oocytes in the mosquito vector. These results suggest that cocktails of different stage-specific antigens can provide the components necessary to block the development of the malaria parasite at multiple stages of its life cycle.

  18. Enzymatic properties of the lactate dehydrogenase enzyme from Plasmodium falciparum.

    Science.gov (United States)

    Shoemark, Deborah K; Cliff, Matthew J; Sessions, Richard B; Clarke, Anthony R

    2007-06-01

    The lactate dehydrogenase enzyme from Plasmodium falciparum (PfLDH) is a target for antimalarial compounds owing to structural and functional differences from the human isozymes. The plasmodial enzyme possesses a five-residue insertion in the substrate-specificity loop and exhibits less marked substrate inhibition than its mammalian counterparts. Here we provide a comprehensive kinetic analysis of the enzyme by steady-state and transient kinetic methods. The mechanism deduced by product inhibition studies proves that PfLDH shares a common mechanism with the human LDHs, that of an ordered sequential bireactant system with coenzyme binding first. Transient kinetic analysis reveals that the major rate-limiting step is the closure of the substrate-specificity loop prior to hydride transfer, in line with other LDHs. The five-residue insertion in this loop markedly increases substrate specificity compared with the human muscle and heart isoforms.

  19. Artemether-lumefantrine treatment of uncomplicated Plasmodium falciparum malaria

    DEFF Research Database (Denmark)

    Kofoed, Poul-Erik

    2015-01-01

    BACKGROUND: Achieving adequate antimalarial drug exposure is essential for curing malaria. Day 7 blood or plasma lumefantrine concentrations provide a simple measure of drug exposure that correlates well with artemether-lumefantrine efficacy. However, the 'therapeutic' day 7 lumefantrine...... lumefantrine concentrations ≥200 ng/ml and high cure rates in most uncomplicated malaria patients. Three groups are at increased risk of treatment failure: very young children (particularly those underweight-for-age); patients with high parasitemias; and patients in very low transmission intensity areas......-lumefantrine for uncomplicated Plasmodium falciparum malaria, to define therapeutic day 7 lumefantrine concentrations and identify patient factors that substantially alter these concentrations. A systematic review of PubMed, Embase, Google Scholar, ClinicalTrials.gov and conference proceedings identified all relevant studies...

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

    Science.gov (United States)

    Hempel, Casper

    2017-07-01

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

  1. Anti-phospholipid antibodies in patients with Plasmodium falciparum malaria

    DEFF Research Database (Denmark)

    Jakobsen, P H; Morris-Jones, S D; Hviid, L

    1993-01-01

    Plasma levels of antibodies against phosphatidylinositol (PI), phosphatidylcholine (PC) and cardiolipin (CL) were measured by enzyme-linked immunosorbent assay (ELISA) in patients from malaria endemic area of Sudan and The Gambia. Some Sudanese adults produced IgM antibodies against all three types...... of phospholipids (PL) during an acute Plasmodium falciparum infection. The anti-PL antibody titre returned to preinfection levels in most of the donors 30 days after the disease episode. IgG titres against PI, PC and CL were low. In Gambian children with malaria, IgM antibody titres against PI and PC were...... significantly higher in those with severe malaria than in those with mild malaria. These results show that a proportion of malaria patients produce anti-PL antibodies during infection and that titres of these antibodies are associated with the severity of disease....

  2. Isoprenoid biosynthesis in the erythrocytic stages of Plasmodium falciparum

    Directory of Open Access Journals (Sweden)

    Fabiana Morandi Jordão

    2011-08-01

    Full Text Available The development of new drugs is one strategy for malaria control. Biochemical pathways localised in the apicoplast of the parasite, such as the synthesis of isoprenic precursors, are excellent targets because they are different or absent in the human host. Isoprenoids are a large and highly diverse group of natural products with many functions and their synthesis is essential for the parasite's survival. During the last few years, the genes, enzymes, intermediates and mechanisms of this biosynthetic route have been elucidated. In this review, we comment on some aspects of the methylerythritol phosphate pathway and discuss the presence of diverse isoprenic products such as dolichol, ubiquinone, carotenoids, menaquinone and isoprenylated proteins, which are biosynthesised during the intraerythrocytic stages of Plasmodium falciparum.

  3. Plasmodium falciparum STEVOR proteins impact erythrocyte mechanical properties

    Science.gov (United States)

    Sanyal, Sohini; Egée, Stéphane; Bouyer, Guillaume; Perrot, Sylvie; Safeukui, Innocent; Bischoff, Emmanuel; Buffet, Pierre; Deitsch, Kirk W.; Mercereau-Puijalon, Odile; David, Peter H.

    2012-01-01

    Infection of erythrocytes with the human malaria parasite, Plasmodium falciparum, results in dramatic changes to the host cell structure and morphology. The predicted functional localization of the STEVOR proteins at the erythrocyte surface suggests that they may be involved in parasite-induced modifications of the erythrocyte membrane during parasite development. To address the biologic function of STEVOR proteins, we subjected a panel of stevor transgenic parasites and wild-type clonal lines exhibiting different expression levels for stevor genes to functional assays exploring parasite-induced modifications of the erythrocyte membrane. Using this approach, we show that stevor expression impacts deformability of the erythrocyte membrane. This process may facilitate parasite sequestration in deep tissue vasculature. PMID:22106347

  4. Modeling Metabolism and Stage-Specific Growth of Plasmodium falciparum HB3 during the Intraerythrocytic Development Cycle

    Science.gov (United States)

    2014-01-01

    metabolism and stage-specific growth of Plasmodium falciparum HB3 during the intraerythrocytic developmental cycle† Xin Fang, Jaques Reifman* and Anders...Wallqvist The human malaria parasite Plasmodium falciparum goes through a complex life cycle, including a roughly 48-hour-long intraerythrocytic...disease warrant basic research into the different mechanisms used by Plasmodium falciparum, the most virulent causative agent of malaria, to survive and

  5. Capture ELISA for IgM antibodies against Plasmodium falciparum glutamate rich protein

    DEFF Research Database (Denmark)

    Dziegiel, M; Borre, Mette; Petersen, E

    1992-01-01

    This report describes a novel mu chain capture ELISA for the detection of IgM antibodies against a Plasmodium falciparum antigen. A fragment of the 220 kDa P. falciparum glutamate rich protein containing amino acid residues 489-1271 was expressed in E. coli as a recombinant chimeric beta-galactosidase...

  6. Drug resistance and genetic diversity of Plasmodium falciparum parasites from Suriname

    NARCIS (Netherlands)

    Peek, Ron; van Gool, Tom; Panchoe, Daynand; Greve, Sophie; Bus, Ellen; Resida, Lesley

    2005-01-01

    Plasmodium falciparum in Suriname was studied for the presence of drug resistance and genetic variation in blood samples of 86 patients with symptomatic malaria. Drug resistance was predicted by determining point mutations in the chloroquine resistance marker of the P. falciparum chloroquine

  7. Artesunate misuse and Plasmodium falciparum malaria in traveler returning from Africa.

    Science.gov (United States)

    Shahinas, Dea; Lau, Rachel; Khairnar, Krishna; Hancock, David; Pillai, Dylan R

    2010-10-01

    Plasmodium falciparum malaria developed in an African-born traveler who returned to Canada after visiting Nigeria. While there, she took artesunate prophylactically. Isolates had an elevated 50% inhibitory concentration to artemisinin, artesunate, and artemether, compared with that of other African isolates. Inappropriate use of artemisinin derivatives can reduce P. falciparum susceptibility.

  8. Whole-Genome Scans Provide Evidence of Adaptive Evolution in Malawian Plasmodium falciparum Isolates

    DEFF Research Database (Denmark)

    Ocholla, Harold; Preston, Mark D; Mipando, Mwapatsa

    2014-01-01

    BACKGROUND:  Selection by host immunity and antimalarial drugs has driven extensive adaptive evolution in Plasmodium falciparum and continues to produce ever-changing landscapes of genetic variation. METHODS:  We performed whole-genome sequencing of 69 P. falciparum isolates from Malawi and used...

  9. A versatile, high through-put, bead-based phagocytosis assay for Plasmodium falciparum

    DEFF Research Database (Denmark)

    Lloyd, Yukie M.; Ngati, Elise P.; Salanti, Ali

    2017-01-01

    Antibody-mediated phagocytosis is an important immune effector mechanism against Plasmodium falciparum-infected erythrocytes (IE); however, current phagocytosis assays use IE collected from infected individuals or from in vitro cultures of P. falciparum, making them prone to high variation...

  10. Genetics of refractoriness to Plasmodium falciparum in the mosquito Anopheles stephensi

    NARCIS (Netherlands)

    Feldmann, A.M.; Gemert, Geert-Jan van; Vegte-Bolmer, Marga G. van de; Jansen, Ritsert C.

    1998-01-01

    We previously selected a line of the malaria vector mosquito Anopheles stephensi refractory (resistant) to the human malaria parasite Plasmodium falciparum, using in vitro infections with P. falciparum gametocytes. This report presents data on the genetic background of refractoriness. The results of

  11. NF135.C10: a new Plasmodium falciparum clone for controlled human malaria infections

    NARCIS (Netherlands)

    Teirlinck, A.C.; Roestenberg, M.; Vegte-Bolmer, M.G. van de; Scholzen, A.; Heinrichs, M.J.; Siebelink-Stoter, R.; Graumans, W.; Gemert, G.J.A. van; Teelen, K.A.E.M.; Vos, M.W.; Nganou Makamdop, C.K.; Borrmann, S.; Rozier, Y.P.; Erkens, M.A.; Luty, A.J.F.; Hermsen, C.C.; Sim, B.K.; Lieshout, L. van; Hoffman, S.L.; Visser, L.G.; Sauerwein, R.W.

    2013-01-01

    We established a new field clone of Plasmodium falciparum for use in controlled human malaria infections and vaccine studies to complement the current small portfolio of P. falciparum strains, primarily based on NF54. The Cambodian clone NF135.C10 consistently produced gametocytes and generated

  12. Target proteins of the cytosolic thioredoxin in Plasmodium falciparum.

    Science.gov (United States)

    Kawazu, Shin-ichiro; Takemae, Hitoshi; Komaki-Yasuda, Kanako; Kano, Shigeyuki

    2010-06-01

    The target proteins of a cytosolic Trx (PfTrx-1) in Plasmodium falciparum with Trx-affinity chromatography were examined. Based on the Trx protein reduction pathway, we generated a cysteine mutant of PfTrx-1, which captures the target protein as a mixed disulfide intermediate. A number of proteins were captured with PfTrx-1(C33S) immobilized on resin and were eluted by DTT treatment. The PfTrx-1(C33S) immobilized resin-captured proteins were trypsin-digested and analyzed on a liquid chromatography-mass spectrometry system. Analysis of the sequence data against databases assigned 20 proteins, four of which had been found previously in P. falciparum, with the remaining 16 being new targets. The potential Trx-target proteins included those in pathways such as the redox cycle, protein biosynthesis, energy metabolism and signal transduction. We captured 4 enzymes in the glycolysis pathway (hexokinase, glyceraldehyde-3-phosphate dehydrogenase (GAPDH), phosphoglycerate mutase and L-lactate dehydrogenase (LDH)) as Trx-targets, and we found that PfTrx-1 enhanced the activity of PfGAPDH and PfLDH.

  13. Serum enzymes activities in Plasmodium falciparum infection in Southern Pakistan

    Directory of Open Access Journals (Sweden)

    Koay Yen Chin

    2011-05-01

    Full Text Available Objective: Serum levels of lactate dehydrogenase (LDH,aspartate aminotranferase (AST, alanine aminotransferase(ALT, and alkaline phosphatase (ALP were assessed todetermine the liver functions of patients infected withPlasmodium falciparum. The enzyme activities were assessedin 60 malarial patients and a control group of 44 people.Materials and Methods: The data for the study was collectedfrom the survey conducted from Liaquat University of medicaland health sciences Hospital, Hyderabad, Pakaistan. Sample of60 patients aged between 20 and 50 years were collected. Acontrol group of 44 healthy individual adults was also assessedfor comparative purposes. All the malaria patients who visitedthe OPD during the study period enrolled in the study.Results: The LDH activity in male patients was found to be674.89 ± 33.354 IU/L. This is above the control LDH activity of296.59 ± 14.476 IU/L. Similarly, in female patients, the serumLDH activity of 580.25 ± 24.507 IU/L is over twice the controlfemale serum LDH activity of 302.18 ± 18.082 IU/L. Furtherone-way anova test was performed to find any significance ininfected and control male and female.Conclusion: Hepatic dysfunction was found to be associated toP. falciparum malaria infection.

  14. Cloning of Plasmodium falciparum by single-cell sorting

    Science.gov (United States)

    Miao, Jun; Li, Xiaolian; Cui, Liwang

    2010-01-01

    Malaria parasite cloning is traditionally carried out mainly by using the limiting dilution method, which is laborious, imprecise, and unable to distinguish multiply-infected RBCs. In this study, we used a parasite engineered to express green fluorescent protein (GFP) to evaluate a single-cell sorting method for rapidly cloning Plasmodium falciparum. By dividing a two dimensional scattergram from a cell sorter into 17 gates, we determined the parameters for isolating singly-infected erythrocytes and sorted them into individual cultures. Pre-gating of the engineered parasites for GFP allowed the isolation of almost 100% GFP-positive clones. Compared with the limiting dilution method, the number of parasite clones obtained by single-cell sorting was much higher. Molecular analyses showed that parasite isolates obtained by single-cell sorting were highly homogenous. This highly efficient single-cell sorting method should prove very useful for cloning both P. falciparum laboratory populations from genetic manipulation experiments and clinical samples. PMID:20435038

  15. Clinical Factors for Severity of Plasmodium falciparum Malaria in Hospitalized Adults in Thailand

    OpenAIRE

    Patrick Sagaki; Vipa Thanachartwet; Varunee Desakorn; Duangjai Sahassananda; Supat Chamnanchanunt; Wirongrong Chierakul; Punnee Pitisuttithum; Prajej Ruangkanchanasetr

    2013-01-01

    Plasmodium falciparum is a major cause of severe malaria in Southeast Asia, however, there is limited information regarding clinical factors associated with the severity of falciparum malaria from this region. We performed a retrospective case-control study to compare clinical factors and outcomes between patients with severe and non-severe malaria, and to identify clinical factors associated with the requirement for intensive care unit (ICU) admission of patients with severe falciparum malar...

  16. Chemosensitization of Plasmodium falciparum by Probenecid In Vitro

    Science.gov (United States)

    Nzila, Alexis; Mberu, Eddy; Bray, Pat; Kokwaro, Gilbert; Winstanley, Peter; Marsh, Kevin; Ward, Steve

    2003-01-01

    Resistance to drugs can result from changes in drug transport, and this resistance can sometimes be overcome by a second drug that modifies the transport mechanisms of the cell. This strategy has been exploited to partly reverse resistance to chloroquine in Plasmodium falciparum. Studies with human tumor cells have shown that probenecid can reverse resistance to the antifolate methotrexate, but the potential for reversal of antifolate resistance has not been studied in P. falciparum. In the present study we tested the ability of probenecid to reverse antifolate resistance in P. falciparum in vitro. Probenecid, at concentrations that had no effect on parasite viability alone (50 μM), was shown to increase the sensitivity of a highly resistant parasite isolate to the antifolates pyrimethamine, sulfadoxine, chlorcycloguanil, and dapsone by seven-, five-, three-, and threefold, respectively. The equivalent effects against an antifolate-sensitive isolate were activity enhancements of approximately 3-, 6-, 1.2-, and 19-fold, respectively. Probenecid decreased the level of uptake of radiolabeled folic acid, suggesting a transport-based mechanism linked to folate salvage. When probenecid was tested with chloroquine, it chemosensitized the resistant isolate to chloroquine (i.e., enhanced the activity of chloroquine). This enhancement of activity was associated with increased levels of chloroquine accumulation. In conclusion, we have shown that probenecid can chemosensitize malaria parasites to antifolate compounds via a mechanism linked to reduced folate uptake. Notably, this effect is observed in both folate-sensitive and -resistant parasites. In contrast to the activities of antifolate compounds, the effect of probenecid on chloroquine sensitivity was selective for chloroquine-resistant parasites (patent P407595GB [W. P. Thompson & Co., Liverpool, United Kingdom] has been filed to protect this intellectual property). PMID:12821454

  17. Surveillance of artemether-lumefantrine associated Plasmodium falciparum multidrug resistance protein-1 gene polymorphisms in Tanzania

    DEFF Research Database (Denmark)

    Kavishe, Reginald A; Paulo, Petro; Kaaya, Robert D

    2014-01-01

    ) is the recommended first-line drug in treatment of uncomplicated malaria. This study surveyed the distribution of the Plasmodium falciparum multidrug resistance protein-1 single nucleotide polymorphisms (SNPs) associated with increased parasite tolerance to ALu, in Tanzania. METHODS: A total of 687 Plasmodium...

  18. Exitoso cultivo in vitro de gametocitos de Plasmodium falciparum

    Directory of Open Access Journals (Sweden)

    Silvia Blair

    2008-12-01

    Full Text Available Introducción. Los estadios sexuales de Plasmodium falciparum han sido menos estudiados que los estadios asexuales. Al parecer, esto se debe a la carencia de cultivos estandarizados in vitro y a la dificultad de reconocer sus estadios de desarrollo. Estos hechos no permiten el estudio de aspectos biológicos, aspectos metabólicos, expresión de genes y síntesis de proteínas durante los estadios sexuales, temas de interés en la investigación de nuevos medicamentos antipalúdicos, principalmente los aislados de plantas, y la identificación de un potencial blanco contra Plasmodium. Objetivos. Establecer un cultivo in vitro de gametocitos, con la identificación de sus cinco estadios de desarrollo, y asegurar su continua producción. Materiales y métodos. El cultivo in vitro de gametocitos se realizó a partir de la cepa NF54 de P. falciparum en medio RPMI, con determinación de la parasitemia asexual y sexual, adición de glóbulos rojos A-Rh+ sólo el primer día de cultivo y cambio diario del medio con adición de mezcla de gases (90% N2, 5% O2; 5% CO2, asegurándose que el cultivo se mantuviera a 37 °C. Cuando la parasitemia asexual estuvo entre 3% y 5%, se comenzó a agregar el doble de volumen de medio. Resultados. Se obtuvieron gametocitos en estadios I, II y III a partir del día 11 de cultivo y estadios IV y V a partir del día 14 de cultivo. Conclusiones. Se estandarizó un cultivo in vitro para estadios sexuales de P. falciparum que puede usarse para futuros estudios de evaluación de compuestos, naturales o sintéticos, que actúen sobre los gametocitos, lo cual podría permitir el desarrollo de nuevas estrategias de control contra el paludismo.

  19. T cell subtypes and reciprocal inflammatory mediator expression differentiate P. falciparum memory recall responses in asymptomatic and symptomatic malaria patients in southeastern Haiti.

    Science.gov (United States)

    Lehmann, Jason S; Campo, Joseph J; Cicéron, Micheline; Raccurt, Christian P; Boncy, Jacques; Beau De Rochars, Valery E M; Cannella, Anthony P

    2017-01-01

    Asymptomatic Plasmodium falciparum infection is responsible for maintaining malarial disease within human populations in low transmission countries such as Haiti. Investigating differential host immune responses to the parasite as a potential underlying mechanism could help provide insight into this highly complex phenomenon and possibly identify asymptomatic individuals. We performed a cross-sectional analysis of individuals who were diagnosed with malaria in Sud-Est, Haiti by comparing the cellular and humoral responses of both symptomatic and asymptomatic subjects. Plasma samples were analyzed with a P. falciparum protein microarray, which demonstrated serologic reactivity to 3,877 P. falciparum proteins of known serologic reactivity; however, no antigen-antibody reactions delineating asymptomatics from symptomatics were identified. In contrast, differences in cellular responses were observed. Flow cytometric analysis of patient peripheral blood mononuclear cells co-cultured with P. falciparum infected erythrocytes demonstrated a statistically significant increase in the proportion of T regulatory cells (CD4+ CD25+ CD127-), and increases in unique populations of both NKT-like cells (CD3+ CD8+ CD56+) and CD8mid T cells in asymptomatics compared to symptomatics. Also, CD38+/HLA-DR+ expression on γδ T cells, CD8mid (CD56-) T cells, and CD8mid CD56+ NKT-like cells decreased upon exposure to infected erythrocytes in both groups. Cytometric bead analysis of the co-culture supernatants demonstrated an upregulation of monocyte-activating chemokines/cytokines in asymptomatics, while immunomodulatory soluble factors were elevated in symptomatics. Principal component analysis of these expression values revealed a distinct clustering of individual responses within their respective phenotypic groups. This is the first comprehensive investigation of immune responses to P. falciparum in Haiti, and describes unique cell-mediated immune repertoires that delineate individuals

  20. Case Report: A Case ofPlasmodium falciparum hrp2andhrp3Gene Mutation in Bangladesh.

    Science.gov (United States)

    Nima, Maisha Khair; Hougard, Thomas; Hossain, Mohammad Enayet; Kibria, Mohammad Golam; Mohon, Abu Naser; Johora, Fatema Tuj; Rahman, Rajibur; Haque, Rashidul; Alam, Mohammad Shafiul

    2017-10-01

    Several species of Plasmodium are responsible for causing malaria in humans. Proper diagnoses are crucial to case management, because severity and treatment varies between species. Diagnoses can be made using rapid diagnostic tests (RDTs), which detect Plasmodium proteins. Plasmodium falciparum causes the most virulent cases of malaria, and P. falciparum histidine-rich protein 2 (PfHRP2) is a common target of falciparum malaria RDTs. Here we report a case in which a falciparum malaria patient in Bangladesh tested negative on PfHRP2-based RDTs. The negative results can be attributed to a deletion of part of the pfhrp2 gene and frameshift mutations in both pfhrp2 and pfhrp3 gene. This finding may have implications for malaria diagnostics and case management in Bangladesh and other regions of South Asia.

  1. Chondroitin sulfate A-adhering Plasmodium falciparum-infected erythrocytes express functionally important antibody epitopes shared by multiple variants

    DEFF Research Database (Denmark)

    Barfod, Lea; Dobrilovic, Tina; Magistrado, Pamela

    2010-01-01

    Acquired protection from Plasmodium falciparum placental malaria, a major cause of maternal, fetal, and infant morbidity, is mediated by IgG specific for the P. falciparum erythrocyte membrane protein 1 variant VAR2CSA. This protein enables adhesion of P. falciparum-infected erythrocytes to chond......Acquired protection from Plasmodium falciparum placental malaria, a major cause of maternal, fetal, and infant morbidity, is mediated by IgG specific for the P. falciparum erythrocyte membrane protein 1 variant VAR2CSA. This protein enables adhesion of P. falciparum-infected erythrocytes...

  2. [Plasmodium falciparum malaria: evaluation of three imported cases].

    Science.gov (United States)

    İnkaya, Ahmet Çağkan; Kaya, Filiz; Yıldız, İrem; Uzun, Ömrüm; Ergüven, Sibel

    2016-04-01

    Among Plasmodium species the causative agent of malaria in Turkey is P.vivax, however the incidence of imported falciparum malaria cases is steadily increasing. P.falciparum may cause severe malaria with the involvement of central nervous system, acute renal failure, severe anemia or acute respiratory distress syndrome. Furhermore most of the casualties due to malaria are related with P.falciparum. There is recently, a considerable increase in malaria infections especially in tropical areas. In this report, three cases, who have admitted to our hospital with three different clinical presentations of falciparum malaria, and all shared common history of travelling to Africa were presented. First case was a 27 years old, male patient who returned from Malawi seven days ago where he stayed for two weeks. He admitted to our hospital with the complaints of sensation of cold, shivering and fever. In physical examination his body temperature was 37.9°C, C-reactive protein level was high, and the other systemic results were normal. The second case was a 25 years old, male patient who returned from Gambia two weeks ago. He was suffering from fever, headache, shivering and unable to maintain his balance. The patient's body temperature was 38°C. Laboratory tests revealed hyperbilirubinemia and thrombocytopenia. Parasitological examination of the Giemsa-stained peripheral blood smear of these two patients demonstrated ring forms compatible with P.falciparum. Treatment was commenced with arthemeter plus lumefantrine, resulting with complete cure. Third case was a 46 years old, male patient who had been working in Uganda, and returned to Turkey two weeks ago. He had sudden onset of fever, headache, nausea and vomiting and impaired consciousness. His peripheral blood smear revealed ring-formed trophozoites and banana-shaped gametocytes of P.falciparum. Arthemeter plus lumefantrine therapy was started, however, he developed severe thrombocytopenia and jaundice under treatment

  3. Increased serum hepcidin and alterations in blood iron parameters associated with asymptomatic P. falciparum and P. vivax malaria.

    NARCIS (Netherlands)

    Mast, Q. de; Syafruddin, D.; Keijmel, S.; Riekerink, T.O.; Deky, O.; Asih, P.B.; Swinkels, D.W.; Ven, A.J.A.M. van der

    2010-01-01

    BACKGROUND: Asymptomatic Plasmodium spp. infections and anemia are highly prevalent conditions in tropical regions. We studied whether asymptomatic parasitemia induces hepcidin- and/or cytokine-mediated iron maldistribution and anemia. DESIGN AND METHODS: A group of 1197 Indonesian schoolchildren,

  4. Detergent-dependent kinetics of truncated Plasmodium falciparum dihydroorotate dehydrogenase.

    Science.gov (United States)

    Malmquist, Nicholas A; Baldwin, Jeffrey; Phillips, Margaret A

    2007-04-27

    The survival of the malaria parasite Plasmodium falciparum is dependent upon the de novo biosynthesis of pyrimidines. P. falciparum dihydroorotate dehydrogenase (PfDHODH) catalyzes the fourth step in this pathway in an FMN-dependent reaction. The full-length enzyme is associated with the inner mitochondrial membrane, where ubiquinone (CoQ) serves as the terminal electron acceptor. The lipophilic nature of the co-substrate suggests that electron transfer to CoQ occurs at the two-dimensional lipid-solution interface. Here we show that PfDHODH associates with liposomes even in the absence of the N-terminal transmembrane-spanning domain. The association of a series of ubiquinone substrates with detergent micelles was studied by isothermal titration calorimetry, and the data reveal that CoQ analogs with long decyl (CoQ(D)) or geranyl (CoQ(2)) tails partition into detergent micelles, whereas that with a short prenyl tail (CoQ(1)) remains in solution. PfDHODH-catalyzed reduction of CoQ(D) and CoQ(2), but not CoQ(1), is stimulated as detergent concentrations (Tween 80 or Triton X-100) are increased up to their critical micelle concentrations, beyond which activity declines. Steady-state kinetic data acquired for the reaction with CoQ(D) and CoQ(2) in substrate-detergent mixed micelles fit well to a surface dilution kinetic model. In contrast, the data for CoQ(1) as a substrate were well described by solution steady-state kinetics. Our results suggest that the partitioning of lipophilic ubiquinone analogues into detergent micelles needs to be an important consideration in the kinetic analysis of enzymes that utilize these substrates.

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

    Directory of Open Access Journals (Sweden)

    Kendjo Eric

    2003-06-01

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

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

    Science.gov (United States)

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

    2017-05-02

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

  7. Origin and evolution of sulfadoxine resistant Plasmodium falciparum.

    Directory of Open Access Journals (Sweden)

    Sumiti Vinayak

    2010-03-01

    Full Text Available The Thailand-Cambodia border is the epicenter for drug-resistant falciparum malaria. Previous studies have shown that chloroquine (CQ and pyrimethamine resistance originated in this region and eventually spread to other Asian countries and Africa. However, there is a dearth in understanding the origin and evolution of dhps alleles associated with sulfadoxine resistance. The present study was designed to reveal the origin(s of sulfadoxine resistance in Cambodia and its evolutionary relationship to African and South American dhps alleles. We sequenced 234 Cambodian Plasmodium falciparum isolates for the dhps codons S436A/F, A437G, K540E, A581G and A613S/T implicated in sulfadoxine resistance. We also genotyped 10 microsatellite loci around dhps to determine the genetic backgrounds of various alleles and compared them with the backgrounds of alleles prevalent in Africa and South America. In addition to previously known highly-resistant triple mutant dhps alleles SGEGA and AGEAA (codons 436, 437, 540, 581, 613 are sequentially indicated, a large proportion of the isolates (19.3% contained a 540N mutation in association with 437G/581G yielding a previously unreported triple mutant allele, SGNGA. Microsatellite data strongly suggest the strength of selection was greater on triple mutant dhps alleles followed by the double and single mutants. We provide evidence for at least three independent origins for the double mutants, one each for the SGKGA, AGKAA and SGEAA alleles. Our data suggest that the triple mutant allele SGEGA and the novel allele SGNGA have common origin on the SGKGA background, whereas the AGEAA triple mutant was derived from AGKAA on multiple, albeit limited, genetic backgrounds. The SGEAA did not share haplotypes with any of the triple mutants. Comparative analysis of the microsatellite haplotypes flanking dhps alleles from Cambodia, Kenya, Cameroon and Venezuela revealed an independent origin of sulfadoxine resistant alleles in each

  8. Origin and Evolution of Sulfadoxine Resistant Plasmodium falciparum

    Science.gov (United States)

    Mixson-Hayden, Tonya; McCollum, Andrea M.; Sem, Rithy; Shah, Naman K.; Lim, Pharath; Muth, Sinuon; Rogers, William O.; Fandeur, Thierry; Barnwell, John W.; Escalante, Ananias A.; Wongsrichanalai, Chansuda; Ariey, Frederick; Meshnick, Steven R.; Udhayakumar, Venkatachalam

    2010-01-01

    The Thailand-Cambodia border is the epicenter for drug-resistant falciparum malaria. Previous studies have shown that chloroquine (CQ) and pyrimethamine resistance originated in this region and eventually spread to other Asian countries and Africa. However, there is a dearth in understanding the origin and evolution of dhps alleles associated with sulfadoxine resistance. The present study was designed to reveal the origin(s) of sulfadoxine resistance in Cambodia and its evolutionary relationship to African and South American dhps alleles. We sequenced 234 Cambodian Plasmodium falciparum isolates for the dhps codons S436A/F, A437G, K540E, A581G and A613S/T implicated in sulfadoxine resistance. We also genotyped 10 microsatellite loci around dhps to determine the genetic backgrounds of various alleles and compared them with the backgrounds of alleles prevalent in Africa and South America. In addition to previously known highly-resistant triple mutant dhps alleles SGEGA and AGEAA (codons 436, 437, 540, 581, 613 are sequentially indicated), a large proportion of the isolates (19.3%) contained a 540N mutation in association with 437G/581G yielding a previously unreported triple mutant allele, SGNGA. Microsatellite data strongly suggest the strength of selection was greater on triple mutant dhps alleles followed by the double and single mutants. We provide evidence for at least three independent origins for the double mutants, one each for the SGKGA, AGKAA and SGEAA alleles. Our data suggest that the triple mutant allele SGEGA and the novel allele SGNGA have common origin on the SGKGA background, whereas the AGEAA triple mutant was derived from AGKAA on multiple, albeit limited, genetic backgrounds. The SGEAA did not share haplotypes with any of the triple mutants. Comparative analysis of the microsatellite haplotypes flanking dhps alleles from Cambodia, Kenya, Cameroon and Venezuela revealed an independent origin of sulfadoxine resistant alleles in each of these regions

  9. Evaluation of DNA Recombinant Methodologies for the Diagnosis of Plasmodium falciparum and their Comparison with the Microscopy Assay

    Directory of Open Access Journals (Sweden)

    L Urdaneta

    1998-09-01

    Full Text Available Since 1984, DNA tests based on the highly repeated subtelomeric sequences of Plasmodium falciparum (rep 20 have been frequently used in malaria diagnosis. Rep 20 is very specific for this parasite, and is made of 21 bp units, organized in repeated blocks with direct and inverted orientation. Based in this particular organization, we selected a unique consensus oligonucleotide (pf-21 to drive a PCR reaction coupled to hybridization to non-radioactive labeled probes. The pf-21 unique oligo PCR (pf-21-I assay produced DNA amplification fingerprints when was applied on purified P. falciparum DNA samples (Brazil and Colombia, as well as in patient's blood samples from a large area of Venezuela. The performance of the Pf-21-I assay was compared against Giemsa stained thick blood smears from samples collected at a malaria endemic area of the Bolívar State, Venezuela, at the field station of Malariología in Tumeremo. Coupled to non-radioactive hybridization the pf-21-I performed better than the traditional microscopic method with a r=1.7:1. In the case of mixed infections the r value of P. falciparum detection increased to 2.5:1. The increased diagnostic sensitivity of the test produced with this homologous oligonucleotide could provide an alternative to the epidemiological diagnosis of P. falciparum being currently used in Venezuela endemic areas, where low parasitemia levels and asymptomatic malaria are frequent. In addition, the DNA fingerprint could be tested in molecular population studies

  10. Impact of climate variability on Plasmodium vivax and Plasmodium falciparum malaria in Yunnan Province, China.

    Science.gov (United States)

    Bi, Yan; Yu, Weiwei; Hu, Wenbiao; Lin, Hualiang; Guo, Yuming; Zhou, Xiao-Nong; Tong, Shilu

    2013-12-17

    Malaria remains a public health problem in the remote and poor area of Yunnan Province, China. Yunnan faces an increasing risk of imported malaria infections from Mekong river neighboring countries. This study aimed to identify the high risk area of malaria transmission in Yunnan Province, and to estimate the effects of climatic variability on the transmission of Plasmodium vivax and Plasmodium falciparum in the identified area. We identified spatial clusters of malaria cases using spatial cluster analysis at a county level in Yunnan Province, 2005-2010, and estimated the weekly effects of climatic factors on P. vivax and P. falciparum based on a dataset of daily malaria cases and climatic variables. A distributed lag nonlinear model was used to estimate the impact of temperature, relative humidity and rainfall up to 10-week lags on both types of malaria parasite after adjusting for seasonal and long-term effects. The primary cluster area was identified along the China-Myanmar border in western Yunnan. A 1°C increase in minimum temperature was associated with a lag 4 to 9 weeks relative risk (RR), with the highest effect at lag 7 weeks for P. vivax (RR = 1.03; 95% CI, 1.01, 1.05) and 6 weeks for P. falciparum (RR = 1.07; 95% CI, 1.04, 1.11); a 10-mm increment in rainfall was associated with RRs of lags 2-4 weeks and 9-10 weeks, with the highest effect at 3 weeks for both P. vivax (RR = 1.03; 95% CI, 1.01, 1.04) and P. falciparum (RR = 1.04; 95% CI, 1.01, 1.06); and the RRs with a 10% rise in relative humidity were significant from lag 3 to 8 weeks with the highest RR of 1.24 (95% CI, 1.10, 1.41) for P. vivax at 5-week lag. Our findings suggest that the China-Myanmar border is a high risk area for malaria transmission. Climatic factors appeared to be among major determinants of malaria transmission in this area. The estimated lag effects for the association between temperature and malaria are consistent with the life cycles of both mosquito vector and malaria

  11. Protein-based signatures of functional evolution in Plasmodium falciparum

    Directory of Open Access Journals (Sweden)

    Day Nicholas PJ

    2011-09-01

    Full Text Available Abstract Background It has been known for over a decade that Plasmodium falciparum proteins are enriched in non-globular domains of unknown function. The potential for these regions of protein sequence to undergo high levels of genetic drift provides a fundamental challenge to attempts to identify the molecular basis of adaptive change in malaria parasites. Results Evolutionary comparisons were undertaken using a set of forty P. falciparum metabolic enzyme genes, both within the hominid malaria clade (P. reichenowi and across the genus (P. chabaudi. All genes contained coding elements highly conserved across the genus, but there were also a large number of regions of weakly or non-aligning coding sequence. These displayed remarkable levels of non-synonymous fixed differences within the hominid malaria clade indicating near complete release from purifying selection (dN/dS ratio at residues non-aligning across genus: 0.64, dN/dS ratio at residues identical across genus: 0.03. Regions of low conservation also possessed high levels of hydrophilicity, a marker of non-globularity. The propensity for such regions to act as potent sources of non-synonymous genetic drift within extant P. falciparum isolates was confirmed at chromosomal regions containing genes known to mediate drug resistance in field isolates, where 150 of 153 amino acid variants were located in poorly conserved regions. In contrast, all 22 amino acid variants associated with drug resistance were restricted to highly conserved regions. Additional mutations associated with laboratory-selected drug resistance, such as those in PfATPase4 selected by spiroindolone, were similarly restricted while mutations in another calcium ATPase (PfSERCA, a gene proposed to mediate artemisinin resistance that reach significant frequencies in field isolates were located exclusively in poorly conserved regions consistent with genetic drift. Conclusion Coding sequences of malaria parasites contain

  12. piggyBac is an effective tool for functional analysis of the Plasmodium falciparum genome

    Directory of Open Access Journals (Sweden)

    Kissinger Jessica C

    2009-05-01

    Full Text Available Abstract Background Much of the Plasmodium falciparum genome encodes hypothetical proteins with limited homology to other organisms. A lack of robust tools for genetic manipulation of the parasite limits functional analysis of these hypothetical proteins and other aspects of the Plasmodium genome. Transposon mutagenesis has been used widely to identify gene functions in many organisms and would be extremely valuable for functional analysis of the Plasmodium genome. Results In this study, we investigated the lepidopteran transposon, piggyBac, as a molecular genetic tool for functional characterization of the Plasmodium falciparum genome. Through multiple transfections, we generated 177 unique P. falciparum mutant clones with mostly single piggyBac insertions in their genomes. Analysis of piggyBac insertion sites revealed random insertions into the P. falciparum genome, in regards to gene expression in parasite life cycle stages and functional categories. We further explored the possibility of forward genetic studies in P. falciparum with a phenotypic screen for attenuated growth, which identified several parasite genes and pathways critical for intra-erythrocytic development. Conclusion Our results clearly demonstrate that piggyBac is a novel, indispensable tool for forward functional genomics in P. falciparum that will help better understand parasite biology and accelerate drug and vaccine development.

  13. Artemisinin-naphthoquine for treating uncomplicated Plasmodium falciparum malaria

    Science.gov (United States)

    Isba, Rachel; Zani, Babalwa; Gathu, Michael; Sinclair, David

    2015-01-01

    Background The World Health Organization (WHO) recommends artemisinin-based combination therapy (ACT) for treating people with Plasmodium falciparum malaria. Five combinations are currently recommended, all administered over three days. Artemisinin-naphthoquine is a new combination developed in China, which is being marketed as a one-day treatment. Although shorter treatment courses may improve adherence, the WHO recommends at least three days of the short-acting artemisinin component to eliminate 90% P. falciparum parasites in the bloodstream, before leaving the longer-acting partner drug to clear the remaining parasites. Objectives To evaluate the efficacy and safety of the artemisinin-naphthoquine combination for treating adults and children with uncomplicated P. falciparum malaria. Search methods We searched the Cochrane Infectious Diseases Group Specialized Register; Cochrane Central Register of Controlled Trials (CENTRAL) published in The Cochrane Library; MEDLINE; EMBASE; and LILACS up to January 2015. We also searched the metaRegister of Controlled Trials (mRCT) using 'malaria' and 'arte* OR dihydroarte*' as search terms. Selection criteria Randomized controlled trials comparing artemisinin-naphthoquine combinations with established WHO-recommended ACTs for the treatment of adults and children with uncomplicated malaria due to P. falciparum. Data collection and analysis Two review authors independently assessed trials for eligibility and risk of bias, and extracted data. We analysed primary outcomes in line with the WHO 'Protocol for assessing and monitoring antimalarial drug efficacy' and compared drugs using risk ratios (RR) and 95% confidence intervals (CI). Secondary outcomes were effects on gametocytes, haemoglobin, and adverse events. We assessed the quality of evidence using the GRADE approach. Main results Four trials, enrolling 740 adults and children, met the inclusion criteria. Artemisinin-naphthoquine was administered as a single dose (two

  14. A molecular marker of artemisinin-resistant Plasmodium falciparum malaria

    Science.gov (United States)

    Ariey, Frédéric; Witkowski, Benoit; Amaratunga, Chanaki; Beghain, Johann; Langlois, Anne-Claire; Khim, Nimol; Kim, Saorin; Duru, Valentine; Bouchier, Christiane; Ma, Laurence; Lim, Pharath; Leang, Rithea; Duong, Socheat; Sreng, Sokunthea; Suon, Seila; Chuor, Char Meng; Bout, Denis Mey; Ménard, Sandie; Rogers, William O.; Genton, Blaise; Fandeur, Thierry; Miotto, Olivo; Ringwald, Pascal; Le Bras, Jacques; Berry, Antoine; Barale, Jean-Christophe; Fairhurst, Rick M.; Benoit-Vical, Françoise; Mercereau-Puijalon, Odile; Ménard, Didier

    2016-01-01

    Plasmodium falciparum resistance to artemisinin derivatives in southeast Asia threatens malaria control and elimination activities worldwide. To monitor the spread of artemisinin resistance, a molecular marker is urgently needed. Here, using whole-genome sequencing of an artemisinin-resistant parasite line from Africa and clinical parasite isolates from Cambodia, we associate mutations in the PF3D7_1343700 kelch propeller domain (‘K13-propeller’) with artemisinin resistance in vitro and in vivo. Mutant K13-propeller alleles cluster in Cambodian provinces where resistance is prevalent, and the increasing frequency of a dominant mutant K13-propeller allele correlates with the recent spread of resistance in western Cambodia. Strong correlations between the presence of a mutant allele, in vitro parasite survival rates and in vivo parasite clearance rates indicate that K13-propeller mutations are important determinants of artemisinin resistance. K13-propeller polymorphism constitutes a useful molecular marker for large-scale surveillance efforts to contain artemisinin resistance in the Greater Mekong Subregion and prevent its global spread. PMID:24352242

  15. The homeostasis of Plasmodium falciparum-infected red blood cells.

    Directory of Open Access Journals (Sweden)

    Jakob M A Mauritz

    2009-04-01

    Full Text Available The asexual reproduction cycle of Plasmodium falciparum, the parasite responsible for severe malaria, occurs within red blood cells. A merozoite invades a red cell in the circulation, develops and multiplies, and after about 48 hours ruptures the host cell, releasing 15-32 merozoites ready to invade new red blood cells. During this cycle, the parasite increases the host cell permeability so much that when similar permeabilization was simulated on uninfected red cells, lysis occurred before approximately 48 h. So how could infected cells, with a growing parasite inside, prevent lysis before the parasite has completed its developmental cycle? A mathematical model of the homeostasis of infected red cells suggested that it is the wasteful consumption of host cell hemoglobin that prevents early lysis by the progressive reduction in the colloid-osmotic pressure within the host (the colloid-osmotic hypothesis. However, two critical model predictions, that infected cells would swell to near prelytic sphericity and that the hemoglobin concentration would become progressively reduced, remained controversial. In this paper, we are able for the first time to correlate model predictions with recent experimental data in the literature and explore the fine details of the homeostasis of infected red blood cells during five model-defined periods of parasite development. The conclusions suggest that infected red cells do reach proximity to lytic rupture regardless of their actual volume, thus requiring a progressive reduction in their hemoglobin concentration to prevent premature lysis.

  16. Recombination hotspots and population structure in Plasmodium falciparum.

    Science.gov (United States)

    Mu, Jianbing; Awadalla, Philip; Duan, Junhui; McGee, Kate M; Joy, Deirdre A; McVean, Gilean A T; Su, Xin-zhuan

    2005-10-01

    Understanding the influences of population structure, selection, and recombination on polymorphism and linkage disequilibrium (LD) is integral to mapping genes contributing to drug resistance or virulence in Plasmodium falciparum. The parasite's short generation time, coupled with a high cross-over rate, can cause rapid LD break-down. However, observations of low genetic variation have led to suggestions of effective clonality: selfing, population admixture, and selection may preserve LD in populations. Indeed, extensive LD surrounding drug-resistant genes has been observed, indicating that recombination and selection play important roles in shaping recent parasite genome evolution. These studies, however, provide only limited information about haplotype variation at local scales. Here we describe the first (to our knowledge) chromosome-wide SNP haplotype and population recombination maps for a global collection of malaria parasites, including the 3D7 isolate, whose genome has been sequenced previously. The parasites are clustered according to continental origin, but alternative groupings were obtained using SNPs at 37 putative transporter genes that are potentially under selection. Geographic isolation and highly variable multiple infection rates are the major factors affecting haplotype structure. Variation in effective recombination rates is high, both among populations and along the chromosome, with recombination hotspots conserved among populations at chromosome ends. This study supports the feasibility of genome-wide association studies in some parasite populations.

  17. Genetic architecture of artemisinin-resistant Plasmodium falciparum.

    Science.gov (United States)

    Miotto, Olivo; Amato, Roberto; Ashley, Elizabeth A; MacInnis, Bronwyn; Almagro-Garcia, Jacob; Amaratunga, Chanaki; Lim, Pharath; Mead, Daniel; Oyola, Samuel O; Dhorda, Mehul; Imwong, Mallika; Woodrow, Charles; Manske, Magnus; Stalker, Jim; Drury, Eleanor; Campino, Susana; Amenga-Etego, Lucas; Thanh, Thuy-Nhien Nguyen; Tran, Hien Tinh; Ringwald, Pascal; Bethell, Delia; Nosten, Francois; Phyo, Aung Pyae; Pukrittayakamee, Sasithon; Chotivanich, Kesinee; Chuor, Char Meng; Nguon, Chea; Suon, Seila; Sreng, Sokunthea; Newton, Paul N; Mayxay, Mayfong; Khanthavong, Maniphone; Hongvanthong, Bouasy; Htut, Ye; Han, Kay Thwe; Kyaw, Myat Phone; Faiz, Md Abul; Fanello, Caterina I; Onyamboko, Marie; Mokuolu, Olugbenga A; Jacob, Christopher G; Takala-Harrison, Shannon; Plowe, Christopher V; Day, Nicholas P; Dondorp, Arjen M; Spencer, Chris C A; McVean, Gilean; Fairhurst, Rick M; White, Nicholas J; Kwiatkowski, Dominic P

    2015-03-01

    We report a large multicenter genome-wide association study of Plasmodium falciparum resistance to artemisinin, the frontline antimalarial drug. Across 15 locations in Southeast Asia, we identified at least 20 mutations in kelch13 (PF3D7_1343700) affecting the encoded propeller and BTB/POZ domains, which were associated with a slow parasite clearance rate after treatment with artemisinin derivatives. Nonsynonymous polymorphisms in fd (ferredoxin), arps10 (apicoplast ribosomal protein S10), mdr2 (multidrug resistance protein 2) and crt (chloroquine resistance transporter) also showed strong associations with artemisinin resistance. Analysis of the fine structure of the parasite population showed that the fd, arps10, mdr2 and crt polymorphisms are markers of a genetic background on which kelch13 mutations are particularly likely to arise and that they correlate with the contemporary geographical boundaries and population frequencies of artemisinin resistance. These findings indicate that the risk of new resistance-causing mutations emerging is determined by specific predisposing genetic factors in the underlying parasite population.

  18. Recombination hotspots and population structure in Plasmodium falciparum.

    Directory of Open Access Journals (Sweden)

    Jianbing Mu

    2005-10-01

    Full Text Available Understanding the influences of population structure, selection, and recombination on polymorphism and linkage disequilibrium (LD is integral to mapping genes contributing to drug resistance or virulence in Plasmodium falciparum. The parasite's short generation time, coupled with a high cross-over rate, can cause rapid LD break-down. However, observations of low genetic variation have led to suggestions of effective clonality: selfing, population admixture, and selection may preserve LD in populations. Indeed, extensive LD surrounding drug-resistant genes has been observed, indicating that recombination and selection play important roles in shaping recent parasite genome evolution. These studies, however, provide only limited information about haplotype variation at local scales. Here we describe the first (to our knowledge chromosome-wide SNP haplotype and population recombination maps for a global collection of malaria parasites, including the 3D7 isolate, whose genome has been sequenced previously. The parasites are clustered according to continental origin, but alternative groupings were obtained using SNPs at 37 putative transporter genes that are potentially under selection. Geographic isolation and highly variable multiple infection rates are the major factors affecting haplotype structure. Variation in effective recombination rates is high, both among populations and along the chromosome, with recombination hotspots conserved among populations at chromosome ends. This study supports the feasibility of genome-wide association studies in some parasite populations.

  19. Structure of Plasmodium falciparum dihydroorotate dehydrogenase with a bound inhibitor.

    Science.gov (United States)

    Hurt, Darrell E; Widom, Joanne; Clardy, Jon

    2006-03-01

    Membrane-associated dihydroorotate dehydrogenase (DHODH) is an antimalarial therapeutic target without an effective inhibitor. Studies on human DHODH (HsDHODH) led to a structural mechanistic model in which respiratory quinones bind in a tunnel formed by the highly variable N-terminus that leads to the flavin mononucleotide-binding site. The therapeutic agents leflunomide (Arava) and brequinar sodium inhibit HsDHODH by binding in this tunnel. Plasmodium falciparum DHODH (PfDHODH) and HsDHODH have markedly different sensitivities to the two drugs. To understand the structural basis of this differential sensitivity and begin a structure-based drug-design cycle for PfDHODH inhibitors, the three-dimensional structure (2.4 Angstroms, R = 20.1%) of PfDHODH bound to the active metabolite of leflunomide was determined by X-ray crystallography. Comparison of the structures of HsDHODH and PfDHODH reveals a completely different binding mode for the same inhibitor in these two catalytically identical enzymes and explains the previously observed species-specific preferential binding. Because no effective inhibitors have been described for PfDHODH, this structure provides critical insight for the design of potential antimalarials.

  20. Chromosome End Repair and Genome Stability in Plasmodium falciparum

    Directory of Open Access Journals (Sweden)

    Susannah F. Calhoun

    2017-08-01

    Full Text Available The human malaria parasite Plasmodium falciparum replicates within circulating red blood cells, where it is subjected to conditions that frequently cause DNA damage. The repair of DNA double-stranded breaks (DSBs is thought to rely almost exclusively on homologous recombination (HR, due to a lack of efficient nonhomologous end joining. However, given that the parasite is haploid during this stage of its life cycle, the mechanisms involved in maintaining genome stability are poorly understood. Of particular interest are the subtelomeric regions of the chromosomes, which contain the majority of the multicopy variant antigen-encoding genes responsible for virulence and disease severity. Here, we show that parasites utilize a competitive balance between de novo telomere addition, also called “telomere healing,” and HR to stabilize chromosome ends. Products of both repair pathways were observed in response to DSBs that occurred spontaneously during routine in vitro culture or resulted from experimentally induced DSBs, demonstrating that both pathways are active in repairing DSBs within subtelomeric regions and that the pathway utilized was determined by the DNA sequences immediately surrounding the break. In combination, these two repair pathways enable parasites to efficiently maintain chromosome stability while also contributing to the generation of genetic diversity.

  1. Multiplication rate variation in the human malaria parasite Plasmodium falciparum.

    Science.gov (United States)

    Murray, Lee; Stewart, Lindsay B; Tarr, Sarah J; Ahouidi, Ambroise D; Diakite, Mahamadou; Amambua-Ngwa, Alfred; Conway, David J

    2017-07-25

    It is important to understand intrinsic variation in asexual blood stage multiplication rates of the most virulent human malaria parasite, Plasmodium falciparum. Here, multiplication rates of long-term laboratory adapted parasite clones and new clinical isolates were measured, using a newly standardised assay of growth from low starting density in replicate parallel cultures with erythrocytes from multiple different donors, across multiple cycles. Multiplication rates of long-term established clones were between 7.6 and 10.5 fold per 48 hours, with clone Dd2 having a higher rate than others (clones 3D7, HB3 and D10). Parasite clone-specific growth was then analysed in co-culture assays with all possible heterologous pairwise combinations. This showed that co-culture of different parasites did not affect their replication rates, indicating that there were no suppressive interactions operating between parasites. Multiplication rates of eleven new clinical isolates were measured after a few weeks of culture, and showed a spectrum of replication rates between 2.3 and 6.0 fold per 48 hours, the entire range being lower than for the long-term laboratory adapted clones. Multiplication rate estimates remained stable over time for several isolates tested repeatedly up to three months after culture initiation, indicating considerable persistence of this important trait variation.

  2. Artemether-lumefantrine treatment of uncomplicated Plasmodium falciparum malaria

    DEFF Research Database (Denmark)

    Kofoed, Poul-Erik

    2015-01-01

    BACKGROUND: Achieving adequate antimalarial drug exposure is essential for curing malaria. Day 7 blood or plasma lumefantrine concentrations provide a simple measure of drug exposure that correlates well with artemether-lumefantrine efficacy. However, the 'therapeutic' day 7 lumefantrine concentr......BACKGROUND: Achieving adequate antimalarial drug exposure is essential for curing malaria. Day 7 blood or plasma lumefantrine concentrations provide a simple measure of drug exposure that correlates well with artemether-lumefantrine efficacy. However, the 'therapeutic' day 7 lumefantrine......-lumefantrine for uncomplicated Plasmodium falciparum malaria, to define therapeutic day 7 lumefantrine concentrations and identify patient factors that substantially alter these concentrations. A systematic review of PubMed, Embase, Google Scholar, ClinicalTrials.gov and conference proceedings identified all relevant studies...... lumefantrine concentrations ≥200 ng/ml and high cure rates in most uncomplicated malaria patients. Three groups are at increased risk of treatment failure: very young children (particularly those underweight-for-age); patients with high parasitemias; and patients in very low transmission intensity areas...

  3. Catechin Isolated from Garcinia celebica Leaves Inhibit Plasmodium falciparum Growth through the Induction of Oxidative Stress.

    Science.gov (United States)

    Abdulah, Rizky; Suradji, Eka W; Subarnas, Anas; Supratman, Unang; Sugijanto, Milyadi; Diantini, Ajeng; Lestari, Keri; Barliana, Melisa I; Kawazu, Shinichiro; Koyama, Hiroshi

    2017-07-01

    Resistance of antimalarial drugs to Plasmodium falciparum has become a major concern in malaria eradication. Although it is also affected by several socioeconomic factors, a new antiplasmodial agent is needed for a global malaria control program. In this study, we attempted to uncover the antiplasmodial properties of Garcinia celebica, an Indonesian medicinal plant, along with the responsible compound and its possible mechanism. The G. celebica leaves were ethanol extracted and fractionated based on their polarity using n-hexane, ethyl acetate, and water. The antiplasmodial activity was tested in vitro against chloroquine-resistant P. falciparum at 100 μg/ml for 72 h. The active compound of the most active ethyl acetate fraction was subsequently isolated using column chromatography and identified by nuclear magnetic resonance. The IC50 of (+)-catechin, the characterized compound, against P. falciparum was 198 μM in 24 h and experiment. The isolated catechin inhibited P. falciparum growth in both trophozoite and schizont stages. An additional experiment also suggests that the antiplasmodial property of catechin occurs through the induction of the oxidative stress to P. falciparum. This result shows that the potential of catechin and its antimalarial properties should be explored further. Garcinia celebica leaf extract and fractions inhibit Plasmodium falciparum growthCatechin, the active compound of Garcinia celebica leaf extract, inhibits Plasmodium falciparum growth in a time- and dose-dependent manner Abbreviations used: RBC: Red Blood Cells; IC50: Inhibition Concentrattino 50; MeOH: Methanol; RPMI: Roswell Park Memorial Institute; EI: Electron Ionization.

  4. Plasmodium falciparum and Plasmodium vivax specific lactate dehydrogenase: genetic polymorphism study from Indian isolates.

    Science.gov (United States)

    Keluskar, Priyadarshan; Singh, Vineeta; Gupta, Purva; Ingle, Sanjay

    2014-08-01

    Control and eradication of malaria is hindered by the acquisition of drug resistance by Plasmodium species. This has necessitated a persistent search for novel drugs and more efficient targets. Plasmodium species specific lactate dehydrogenase is one of the potential therapeutic and diagnostic targets, because of its indispensable role in endoerythrocytic stage of the parasite. A target molecule that is highly conserved in the parasite population can be more effectively used in diagnostics and therapeutics, hence, in the present study polymorphism in PfLDH (Plasmodiumfalciparum specific LDH) and PvLDH (Plasmodiumvivax specific LDH) genes was analyzed using PCR-single strand confirmation polymorphism (PCR-SSCP) and sequencing. Forty-six P. falciparum and thirty-five P. vivax samples were screened from different states of India. Our findings have revealed presence of a single PfLDH genotype and six PvLDH genotypes among the studied samples. Interestingly, along with synonymous substitutions, nonsynonymous substitutions were reported to be present for the first time in the PvLDH genotypes. Further, through amino acid sequence alignment and homology modeling studies we observed that the catalytic residues were conserved in all PvLDH genotypes and the nonsynonymous substitutions have not altered the enzyme structure significantly. Evolutionary genetics studies have confirmed that PfLDH and PvLDH loci are under strong purifying selection. Phylogenetic analysis of the pLDH gene sequences revealed that P. falciparum compared to P. vivax, has recent origin. The study therefore supports PfLDH and PvLDH as suitable therapeutic and diagnostic targets as well as phylogenetic markers to understand the genealogy of malaria species. Copyright © 2014 Elsevier B.V. All rights reserved.

  5. Adjunctive therapy for cerebral malaria and other severe forms of Plasmodium falciparum malaria

    OpenAIRE

    John, Chandy C; Kutamba, Elizabeth; Mugarura, Keith; Opoka, Robert O

    2010-01-01

    Severe malaria due to Plasmodium falciparum causes more than 800,000 deaths every year. Primary therapy with quinine or artesunate is generally effective in controlling P. falciparum parasitemia, but mortality from cerebral malaria and other forms of severe malaria remains unacceptably high. Long-term cognitive impairment is also common in children with cerebral malaria. Of the numerous adjunctive therapies for cerebral malaria and severe malaria studied over the past five decades, only one (...

  6. Static and Microfluidic Live Imaging Studies of Plasmodium falciparum Invasion Phenotypes

    OpenAIRE

    Lin, Yen-Chun

    2018-01-01

    Severe malaria caused by $\\textit{Plasmodium falciparum}$ ($\\textit{P. falciparum}$) remains a leading cause of death in many low and middle income countries. The intraerythrocytic reproduction cycle of the parasite is responsible for all the symptoms and mortality of malaria. The merozoite, first invade a red blood cell (RBC) in the circulation, then grows, develops and multiplies within it by clonal division. Merozoite invasion is a complex process involving dynamic interactions between lig...

  7. Differential antibody response of Gambian donors to soluble Plasmodium falciparum antigens

    DEFF Research Database (Denmark)

    Jakobsen, P H; Riley, E M; Allen, S J

    1991-01-01

    A seroepidemiological and clinical study was performed in an area of West Africa (The Gambia) where Plasmodium falciparum is endemic with seasonal transmission. Plasma samples were tested by intermediate gel immunoelectrophoresis for antibodies against 7 soluble P. falciparum antigens. There were...... who had had a documented attack of clinical malaria or parasitaemia. There was no difference in antibody profiles to soluble antigens between children with sickle cell trait and children with normal haemoglobin....

  8. Haptoglobin 1-1 is associated with susceptibility to severe Plasmodium falciparum malaria

    DEFF Research Database (Denmark)

    Quaye, I K; Ekuban, F A; Goka, B Q

    2000-01-01

    The haptoglobin (Hp) phenotypes were determined by polyacrylamide-gel electrophoresis in plasma samples obtained in 1997 from 113 Plasmodium falciparum malaria patients (aged 1-12 years) with strictly defined cerebral malaria, severe malarial anaemia, or uncomplicated malaria and 42 age-matched h......The haptoglobin (Hp) phenotypes were determined by polyacrylamide-gel electrophoresis in plasma samples obtained in 1997 from 113 Plasmodium falciparum malaria patients (aged 1-12 years) with strictly defined cerebral malaria, severe malarial anaemia, or uncomplicated malaria and 42 age...

  9. Imbalanced distribution of Plasmodium falciparum MSP-1 genotypes related to sickle-cell trait.

    Science.gov (United States)

    Ntoumi, F; Rogier, C; Dieye, A; Trape, J F; Millet, P; Mercereau-Puijalon, O

    1997-09-01

    The sickle-cell trait protects against severe Plasmodium falciparum malaria and reduces susceptibility to mild malaria but does not prevent infection. The exact mechanism of this protection remains unclear. We have hypothesized that AS individuals are protected by virtue of being less susceptible to a subset of parasite strains; thus we compared some genetic characteristics of parasites infecting AS and AA subjects. Blood was collected from asymptomatic individuals living in two different regions of Africa. The polymorphic MSP-1 and MSP-2 loci were genotyped using a PCR-based methodology. Individual alleles were identified by size polymorphism, amplification using family-specific primers, and hybridization using family-specific probes. Multivariate logistic regression was used to analyze allele distribution. In Senegalese carriers, age and hemoglobin type influenced differently the distribution of the three MSP-1 families and had an impact on distinct individual alleles, whereas the distribution of MSP-2 alleles was marginally affected. There was no influence of other genetic traits, including the HLA Bw53 genotype, or factors such as place of residence within the village. In a cohort of Gabonese schoolchildren in which the influence of age was abrogated, a similar imbalance in the MSP-1 allelic distribution but not of MSP-2 allelic distribution by hemoglobin type was observed. The influence of the host's hemoglobin type on P. falciparum genotypes suggests that parasite fitness for a specific host is strain-dependent, which is consistent with our hypothesis that innate resistance might result from reduced fitness of some parasite strains for individuals with sickle-cell traits.

  10. Potentiation of Artemisinin Activity against Chloroquine-Resistant Plasmodium falciparum Strains by Using Heme Models

    Science.gov (United States)

    Benoit-Vical, Françoise; Robert, Anne; Meunier, Bernard

    1999-01-01

    The influence of different metalloporphyrin derivatives on the antimalarial activity of artemisinin was studied with two chloroquine-resistant strains of Plasmodium falciparum (FcB1-Colombia and FcM29-Cameroon) cultured in human erythrocytes. This potentiation study indicates that the manganese complex of meso-tetrakis(4-sulfonatophenyl)porphyrin has a significant synergistic effect on the activity of artemisinin against both Plasmodium strains. PMID:10508044

  11. Crystal structure of truncated aspartate transcarbamoylase from Plasmodium falciparum.

    Science.gov (United States)

    Lunev, Sergey; Bosch, Soraya S; Batista, Fernando de Assis; Wrenger, Carsten; Groves, Matthew R

    2016-07-01

    The de novo pyrimidine-biosynthesis pathway of Plasmodium falciparum is a promising target for antimalarial drug discovery. The parasite requires a supply of purines and pyrimidines for growth and proliferation and is unable to take up pyrimidines from the host. Direct (or indirect) inhibition of de novo pyrimidine biosynthesis via dihydroorotate dehydrogenase (PfDHODH), the fourth enzyme of the pathway, has already been shown to be lethal to the parasite. In the second step of the plasmodial pyrimidine-synthesis pathway, aspartate and carbamoyl phosphate are condensed to N-carbamoyl-L-aspartate and inorganic phosphate by aspartate transcarbamoylase (PfATC). In this paper, the 2.5 Å resolution crystal structure of PfATC is reported. The space group of the PfATC crystals was determined to be monoclinic P21, with unit-cell parameters a = 87.0, b = 103.8, c = 87.1 Å, α = 90.0, β = 117.7, γ = 90.0°. The presented PfATC model shares a high degree of homology with the catalytic domain of Escherichia coli ATC. There is as yet no evidence of the existence of a regulatory domain in PfATC. Similarly to E. coli ATC, PfATC was modelled as a homotrimer in which each of the three active sites is formed at the oligomeric interface. Each active site comprises residues from two adjacent subunits in the trimer with a high degree of evolutional conservation. Here, the activity loss owing to mutagenesis of the key active-site residues is also described.

  12. Functional analysis of sirtuin genes in multiple Plasmodium falciparum strains.

    Directory of Open Access Journals (Sweden)

    Catherine J Merrick

    Full Text Available Plasmodium falciparum, the causative agent of severe human malaria, employs antigenic variation to avoid host immunity. Antigenic variation is achieved by transcriptional switching amongst polymorphic var genes, enforced by epigenetic modification of chromatin. The histone-modifying 'sirtuin' enzymes PfSir2a and PfSir2b have been implicated in this process. Disparate patterns of var expression have been reported in patient isolates as well as in cultured strains. We examined var expression in three commonly used laboratory strains (3D7, NF54 and FCR-3 in parallel. NF54 parasites express significantly lower levels of var genes compared to 3D7, despite the fact that 3D7 was originally a clone of the NF54 strain. To investigate whether this was linked to the expression of sirtuins, genetic disruption of both sirtuins was attempted in all three strains. No dramatic changes in var gene expression occurred in NF54 or FCR-3 following PfSir2b disruption, contrasting with previous observations in 3D7. In 3D7, complementation of the PfSir2a genetic disruption resulted in a significant decrease in previously-elevated var gene expression levels, but with the continued expression of multiple var genes. Finally, rearranged chromosomes were observed in the 3D7 PfSir2a knockout line. Our results focus on the potential for parasite genetic background to contribute to sirtuin function in regulating virulence gene expression and suggest a potential role for sirtuins in maintaining genome integrity.

  13. Functional analysis of sirtuin genes in multiple Plasmodium falciparum strains.

    Science.gov (United States)

    Merrick, Catherine J; Jiang, Rays H Y; Skillman, Kristen M; Samarakoon, Upeka; Moore, Rachel M; Dzikowski, Ron; Ferdig, Michael T; Duraisingh, Manoj T

    2015-01-01

    Plasmodium falciparum, the causative agent of severe human malaria, employs antigenic variation to avoid host immunity. Antigenic variation is achieved by transcriptional switching amongst polymorphic var genes, enforced by epigenetic modification of chromatin. The histone-modifying 'sirtuin' enzymes PfSir2a and PfSir2b have been implicated in this process. Disparate patterns of var expression have been reported in patient isolates as well as in cultured strains. We examined var expression in three commonly used laboratory strains (3D7, NF54 and FCR-3) in parallel. NF54 parasites express significantly lower levels of var genes compared to 3D7, despite the fact that 3D7 was originally a clone of the NF54 strain. To investigate whether this was linked to the expression of sirtuins, genetic disruption of both sirtuins was attempted in all three strains. No dramatic changes in var gene expression occurred in NF54 or FCR-3 following PfSir2b disruption, contrasting with previous observations in 3D7. In 3D7, complementation of the PfSir2a genetic disruption resulted in a significant decrease in previously-elevated var gene expression levels, but with the continued expression of multiple var genes. Finally, rearranged chromosomes were observed in the 3D7 PfSir2a knockout line. Our results focus on the potential for parasite genetic background to contribute to sirtuin function in regulating virulence gene expression and suggest a potential role for sirtuins in maintaining genome integrity.

  14. Standardizing estimates of the Plasmodium falciparum parasite rate

    Directory of Open Access Journals (Sweden)

    Smith David L

    2007-09-01

    Full Text Available Abstract Background The Plasmodium falciparum parasite rate (PfPR is a commonly reported index of malaria transmission intensity. PfPR rises after birth to a plateau before declining in older children and adults. Studies of populations with different age ranges generally report average PfPR, so age is an important source of heterogeneity in reported PfPR data. This confounds simple comparisons of PfPR surveys conducted at different times or places. Methods Several algorithms for standardizing PfPR were developed using 21 studies that stratify in detail PfPR by age. An additional 121 studies were found that recorded PfPR from the same population over at least two different age ranges; these paired estimates were used to evaluate these algorithms. The best algorithm was judged to be the one that described most of the variance when converting the PfPR pairs from one age-range to another. Results The analysis suggests that the relationship between PfPR and age is predictable across the observed range of malaria endemicity. PfPR reaches a peak after about two years and remains fairly constant in older children until age ten before declining throughout adolescence and adulthood. The PfPR pairs were poorly correlated; using one to predict the other would explain only 5% of the total variance. By contrast, the PfPR predicted by the best algorithm explained 72% of the variance. Conclusion The PfPR in older children is useful for standardization because it has good biological, epidemiological and statistical properties. It is also historically consistent with the classical categories of hypoendemic, mesoendemic and hyperendemic malaria. This algorithm provides a reliable method for standardizing PfPR for the purposes of comparing studies and mapping malaria endemicity. The scripts for doing so are freely available to all.

  15. Alterations in cytokines and haematological parameters during the acute and convalescent phases of Plasmodium falciparum and Plasmodium vivax infections

    Directory of Open Access Journals (Sweden)

    Rodrigo Nunes Rodrigues-da-Silva

    2014-04-01

    Full Text Available Haematological and cytokine alterations in malaria are a broad and controversial subject in the literature. However, few studies have simultaneously evaluated various cytokines in a single patient group during the acute and convalescent phases of infection. The aim of this study was to sequentially characterise alterations in haematological patters and circulating plasma cytokine and chemokine levels in patients infected with Plasmodium vivax or Plasmodium falciparum from a Brazilian endemic area during the acute and convalescent phases of infection. During the acute phase, thrombocytopaenia, eosinopaenia, lymphopaenia and an increased number of band cells were observed in the majority of the patients. During the convalescent phase, the haematologic parameters returned to normal. During the acute phase, P. vivax and P. falciparum patients had significantly higher interleukin (IL-6, IL-8, IL-17, interferon-γ, tumour necrosis factor (TNF-α, macrophage inflammatory protein-1β and granulocyte-colony stimulating factor levels than controls and maintained high levels during the convalescent phase. IL-10 was detected at high concentrations during the acute phase, but returned to normal levels during the convalescent phase. Plasma IL-10 concentration was positively correlated with parasitaemia in P. vivax and P. falciparum-infected patients. The same was true for the TNF-α concentration in P. falciparum-infected patients. Finally, the haematological and cytokine profiles were similar between uncomplicated P. falciparum and P. vivax infections.

  16. A deep sequencing approach to estimate Plasmodium falciparum complexity of infection (COI) and explore apical membrane antigen 1 diversity.

    Science.gov (United States)

    Miller, Robin H; Hathaway, Nicholas J; Kharabora, Oksana; Mwandagalirwa, Kashamuka; Tshefu, Antoinette; Meshnick, Steven R; Taylor, Steve M; Juliano, Jonathan J; Stewart, V Ann; Bailey, Jeffrey A

    2017-12-16

    Humans living in regions with high falciparum malaria transmission intensity harbour multi-strain infections comprised of several genetically distinct malaria haplotypes. The number of distinct malaria parasite haplotypes identified from an infected human host at a given time is referred to as the complexity of infection (COI). In this study, an amplicon-based deep sequencing method targeting the Plasmodium falciparum apical membrane antigen 1 (pfama1) was utilized to (1) investigate the relationship between P. falciparum prevalence and COI, (2) to explore the population genetic structure of P. falciparum parasites from malaria asymptomatic individuals participating in the 2007 Demographic and Health Survey (DHS) in the Democratic Republic of Congo (DRC), and (3) to explore selection pressures on geospatially divergent parasite populations by comparing AMA1 amino acid frequencies in the DRC and Mali. A total of 900 P. falciparum infections across 11 DRC provinces were examined. Deep sequencing of both individuals, for COI analysis, and pools of individuals, to examine population structure, identified 77 unique pfama1 haplotypes. The majority of individual infections (64.5%) contained polyclonal (COI > 1) malaria infections based on the presence of genetically distinct pfama1 haplotypes. A minimal correlation between COI and malaria prevalence as determined by sensitive real-time PCR was identified. Population genetic analyses revealed extensive haplotype diversity, the vast majority of which was shared across the sites. AMA1 amino acid frequencies were similar between parasite populations in the DRC and Mali. Amplicon-based deep sequencing is a useful tool for the detection of multi-strain infections that can aid in the understanding of antigen heterogeneity of potential malaria vaccine candidates, population genetics of malaria parasites, and factors that influence complex, polyclonal malaria infections. While AMA1 and other diverse markers under balancing

  17. Plasmodium falciparum Produces Prostaglandins that are Pyrogenic, Somnogenic, and Immunosuppressive Substances in Humans

    OpenAIRE

    Kilunga Kubata, B.; Eguchi, Naomi; Urade, Yoshihiro; Yamashita, Kouwa; Mitamura, Toshihide; Tai, Kumiko; Hayaishi, Osamu; Horii, Toshihiro

    1998-01-01

    Plasmodium falciparum causes the most severe form of human malaria, which kills ∼1.5–2.7 million people every year, but the molecular mechanisms underlying the clinical symptoms and the host–parasite interaction remain unclear. We show here that P. falciparum produces prostaglandins (PGs) D2, E2, and F2α. After incubation with 1 mM arachidonic acid (AA), cell homogenates of P. falciparum produced PGs as determined by enzyme immunoassay and gas chromatography–selected ion monitoring. PG produc...

  18. Biomarkers of Plasmodium falciparum infection during pregnancy in women living in northeastern Tanzania

    DEFF Research Database (Denmark)

    Boström, Stéphanie; Ibitokou, Samad; Oesterholt, Mayke

    2012-01-01

    In pregnant women, Plasmodium falciparum infections are an important cause of maternal morbidity as well as fetal and neonatal mortality. Erythrocytes infected by these malaria-causing parasites accumulate through adhesive interactions in placental intervillous spaces, thus evading detection......, chemokines and angiogenic factors in peripheral plasma samples, taken on multiple sequential occasions during pregnancy up to and including delivery, from P. falciparum-infected women and matched uninfected controls. The results show that during healthy, uninfected pregnancies the levels of most of the panel...... markers of P. falciparum infection during pregnancy, but placental histology results would need to be included to verify these findings....

  19. Producción de proteínas recombinantes de Plasmodium falciparum en Escherichia coli

    OpenAIRE

    Ángela Patricia Guerra; Eliana Patricia Calvo; Moisés Wasserman; Jacqueline Chaparro-Olaya

    2016-01-01

    Introducción. La producción de proteínas recombinantes es fundamental para el estudio funcional de las proteínas de Plasmodium falciparum. Sin embargo, las proteínas recombinantes de P. falciparum están entre las más difíciles de expresar y, cuando lo hacen, usualmente se agregan dentro de cuerpos de inclusión insolubles. Objetivo. Evaluar la producción de cuatro proteínas de P. falciparum usando como sistema de expresión dos cepas de Escherichia coli genéticamente modificadas para favorec...

  20. Competitive endothelial adhesion between Plasmodium falciparum isolates under physiological flow conditions

    Directory of Open Access Journals (Sweden)

    Molyneux Malcolm

    2009-09-01

    Full Text Available Abstract Background Sequestration of parasitized red blood cells in the microvasculature of major organs involves a sequence of events that is believed to contribute to the pathogenesis of severe falciparum malaria. Plasmodium falciparum infections are commonly composed of multiple subpopulations of parasites with varied adhesive properties. A key question is: do these subpopulations compete for adhesion to endothelium? This study investigated whether, in a laboratory model of cytoadherence, there is competition in binding to endothelium between pRBC infected with P. falciparum of variant adhesive phenotypes, particularly under flow conditions. Methods Four different P. falciparum isolates, of known adherence phenotypes, were matched in pairs, mixed in different proportions and allowed to bind to cultured human endothelium. Using in vitro competitive static and flow-based adhesion assays, that allow simultaneous testing of the adhesive properties of two different parasite lines, adherence levels of paired P. falciparum isolates were quantified and analysed using either non-parametric Wilcoxon's paired signed rank test or Student paired test. Results Study findings show that P. falciparum parasite lines show marked differences in the efficiency of adhesion to endothelium. Conclusion Plasmodium falciparum variants will compete for adhesion to endothelia and variants can be ranked by their efficiency of binding. These findings suggest that variants from a mixed infection will not show uniform cytoadherence and so may vary in their ability to cause disease.

  1. [The acute respiratory distress syndrome in malaria: is it always the prerogative of Plasmodium falciparum?].

    Science.gov (United States)

    Hachimi, M A; Hatim, E A; Moudden, M K; Elkartouti, A; Errami, M; Louzi, L; Hanafi, S M; Mahmoudi, A

    2013-10-01

    Severe malaria causes nearly one million deaths annually in endemic areas and is a public health priority worldwide. Severity associated with the occurrence of acute respiratory distress syndrome (ARDS) is a well-known complication of infection with Plasmodium falciparum and can reach 25% of infected adults. However, ARDS is less often described with other Plasmodium species. We report the case of a young Moroccan soldier who died in an array of ARDS related to malaria of Plasmodium ovale 7 months after his return from an endemic country. Copyright © 2013. Published by Elsevier Masson SAS.

  2. Sulfadoxine-pyrimethamine impairs Plasmodium falciparum gametocyte infectivity and Anopheles mosquito survival.

    NARCIS (Netherlands)

    Kone, A.; Vegte-Bolmer, M.G. van de; Siebelink-Stoter, R.; Gemert, G.J.A. van; Dara, A.; Niangaly, H.; Luty, A.J.F.; Doumbo, O.K.; Sauerwein, R.W.; Djimde, A.A.

    2010-01-01

    Sulfadoxine-pyrimethamine (SP) is currently the drug of choice for intermittent preventive treatment of Plasmodium falciparum both in pregnancy and infancy. A prolonged parasite clearance time conferred by dhfr and dhps mutations is believed to be responsible for increased gametocyte prevalence in

  3. Molecular cloning of a K+ channel from the malaria parasite Plasmodium falciparum

    DEFF Research Database (Denmark)

    Ellekvist, Peter; Ricke, Christina Høier; Litman, Thomas

    2004-01-01

    In most living cells, K(+) channels are important for the generation of the membrane potential and for volume regulation. The parasite Plasmodium falciparum, which causes malignant malaria, must be able to deal with large variations in the ambient K(+) concentration: it is exposed to high...

  4. Cytometric quantification of singlet oxygen in the human malaria parasite Plasmodium falciparum

    NARCIS (Netherlands)

    Butzloff, Sabine; Groves, Matthew R; Wrenger, Carsten; Müller, Ingrid B

    The malaria parasite Plasmodium falciparum proliferates within human erythrocytes and is thereby exposed to a variety of reactive oxygen species (ROS) such as hydrogen peroxide, hydroxyl radical, superoxide anion, and highly reactive singlet oxygen ((1)O(2)). While most ROS are already well studied

  5. Dynamic histone H3 epigenome marking during the intraerythrocytic cycle of Plasmodium falciparum

    DEFF Research Database (Denmark)

    Salcedo-Amaya, Adriana M; van Driel, Marc A; Alako, Blaise T

    2009-01-01

    Epigenome profiling has led to the paradigm that promoters of active genes are decorated with H3K4me3 and H3K9ac marks. To explore the epigenome of Plasmodium falciparum asexual stages, we performed MS analysis of histone modifications and found a general preponderance of H3/H4 acetylation and H3...

  6. Treatment Failure of Dihydroartemisinin/Piperaquine for Plasmodium falciparum Malaria, Vietnam

    Science.gov (United States)

    Phuc, Bui Quang; Duong, Tran Thanh; Dong, Le Than; Loi, Mai Anh; Ménard, Didier; Tarning, Joel; Bustos, Dorina; Ringwald, Pascal; Galappaththy, Gawrie Loku; Thieu, Nguyen Quang

    2017-01-01

    We conducted a study in Binh Phuoc, Vietnam, in 2015 on the therapeutic efficacy of dihydroartemisinin/piperaquine for Plasmodium falciparum malaria. A high number of treatment failures (14/40) was found, and piperaquine resistance in Vietnam was confirmed. A change in the malaria treatment policy for Vietnam is in process. PMID:28322709

  7. Targets and Mechanisms Associated with Protection from Severe Plasmodium falciparum Malaria in Kenyan Children

    DEFF Research Database (Denmark)

    Murungi, Linda M; Sondén, Klara; Llewellyn, David

    2016-01-01

    Severe malaria (SM) is a life-threatening complication of infection with Plasmodium falciparum Epidemiological observations have long indicated that immunity against SM is acquired relatively rapidly, but prospective studies to investigate its immunological basis are logistically challenging...... the development of vaccines to protect against SM....

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

    NARCIS (Netherlands)

    Shekalaghe, S.; Rutaihwa, M.; Billingsley, P.F.; Chemba, M.; Daubenberger, C.A.; James, E.R.; Mpina, M.; Juma, O. Ali; Schindler, T.; Huber, E.; Gunasekera, A.; Manoj, A.; Simon, B.; Saverino, E.; Church, L.W.; Hermsen, C.C.; Sauerwein, R.W.; Plowe, C.; Venkatesan, M.; Sasi, P.; Lweno, O.; Mutani, P.; Hamad, A.; Mohammed, A.; Urassa, A.; Mzee, T.; Padilla, D.; Ruben, A.; Sim, B.K.; Tanner, M.; Abdulla, S.; Hoffman, S.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.

  9. The efficacy of artemether in the treatment of Plasmodium falciparum malaria in Sudan

    DEFF Research Database (Denmark)

    Elhassan, I M; Satti, G H; Ali, A E

    1994-01-01

    The efficacy of artemether (a qinghaosu derivative) administered intramuscularly for the treatment of Plasmodium falciparum malaria was compared to quinine in an open randomized trial including 54 patients in eastern Sudan, where chloroquine resistance is common. The artemether treatment (5 d...

  10. Filter paper collection of Plasmodium falciparum mRNA for detecting low-density gametocytes

    NARCIS (Netherlands)

    Jones, S.; Sutherland, C.J.; Hermsen, C.; Arens, T.; Teelen, K.; Hallett, R.; Corran, P.; Vegte-Bolmer, M. van der; Sauerwein, R.; Drakeley, C.J.; Bousema, J.T.

    2012-01-01

    ABSTRACT: BACKGROUND: Accurate sampling of sub-microscopic gametocytes is necessary for epidemiological studies to identify the infectious reservoir of Plasmodium falciparum. Detection of gametocyte mRNA achieves sensitive detection, but requires careful handling of samples. Filter papers can be

  11. In Vitro Chemosensitization of Plasmodium falciparum to Antimalarials by Verapamil and Probenecid▿

    OpenAIRE

    Masseno, Victor; Muriithi, Steven; Nzila, Alexis

    2009-01-01

    We tested the effect of probenecid and verapamil in chemosensitizing Plasmodium falciparum to 14 antimalarials using the multidrug-resistant strain V1S and the drug-sensitive 3D7. Verapamil chemosensitizes V1S to quinine and chloroquine. Interestingly, probenecid profoundly chemosensitizes V1S to piperaquine. Thus, probenecid could be used to increase piperaquine efficacy in vivo.

  12. In vitro chemosensitization of Plasmodium falciparum to antimalarials by verapamil and probenecid.

    Science.gov (United States)

    Masseno, Victor; Muriithi, Steven; Nzila, Alexis

    2009-07-01

    We tested the effect of probenecid and verapamil in chemosensitizing Plasmodium falciparum to 14 antimalarials using the multidrug-resistant strain V1S and the drug-sensitive 3D7. Verapamil chemosensitizes V1S to quinine and chloroquine. Interestingly, probenecid profoundly chemosensitizes V1S to piperaquine. Thus, probenecid could be used to increase piperaquine efficacy in vivo.

  13. Dynamic histone H3 epigenome marking during the intraerythrocytic cycle of Plasmodium falciparum.

    NARCIS (Netherlands)

    Salcedo-Amaya, A.M.; Driel, M.A. van; Alako, B.T.; Trelle, M. B.; Elzen, A.M.G. van den; Cohen, A.M.; Janssen-Megens, E.M.; Vegte-Bolmer, M.G. van de; Selzer, R.R.; Iniguez, A.L.; Green, R.D.; Sauerwein, R.W.; Jensen, O.N.; Stunnenberg, H.G.

    2009-01-01

    Epigenome profiling has led to the paradigm that promoters of active genes are decorated with H3K4me3 and H3K9ac marks. To explore the epigenome of Plasmodium falciparum asexual stages, we performed MS analysis of histone modifications and found a general preponderance of H3/H4 acetylation and

  14. Inherited glutathione reductase deficiency and Plasmodium falciparum malaria--a case study

    NARCIS (Netherlands)

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

    2009-01-01

    In Plasmodium falciparum-infected red blood cells (RBCs), the flavoenzyme glutathione reductase (GR) regenerates reduced glutathione, which is essential for antioxidant defense. GR utilizes NADPH produced in the pentose phosphate shunt by glucose-6-phosphate dehydrogenase (G6PD). Thus, conditions

  15. Identification of glycosaminoglycan binding regions in the Plasmodium falciparum encoded placental sequestration ligand, VAR2CSA

    DEFF Research Database (Denmark)

    Resende, Mafalda; Nielsen, Morten A.; Dahlbaeck, Madeleine

    2008-01-01

    Background: Pregnancy malaria is caused by Plasmodium falciparum-infected erythrocytes binding the placental receptor chondroitin sulfate A (CSA). This results in accumulation of parasites in the placenta with severe clinical consequences for the mother and her unborn child. Women become resistan...

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

    NARCIS (Netherlands)

    Fowkes, F.J.; Michon, P.; Pilling, L.; Ripley, R.M.; Tavul, L.; Imrie, H.J.; Woods, C.M.; Mgone, C.S.; Luty, A.J.F.; Day, K.P.

    2008-01-01

    BACKGROUND: The protection afforded by human erythrocyte polymorphisms against the malaria parasite, Plasmodium falciparum, has been proposed to be due to reduced ability of the parasite to invade or develop in erythrocytes. If this were the case, variable levels of parasitaemia and rates of

  17. Plasmodium falciparum Serine/Threonine Phosphoprotein Phosphatases (PPP): From Housekeeper to 'Holy Grail'

    Science.gov (United States)

    Availability of complete genome sequence for Plasmodium falciparum has been useful in drawing a comprehensive metabolic map of the parasite. Distinct and unique metabolic characteristics of the parasite may be exploited as potential targets for new antimalarial drug discovery research. Reversible ph...

  18. Cytoadhesion of Plasmodium falciparum-infected erythrocytes to chondroitin-4-sulfate is cooperative and shear enhanced

    DEFF Research Database (Denmark)

    Rieger, Harden; Yoshikawa, Hiroshi Y; Quadt, Katharina

    2015-01-01

    Infections with the human malaria parasite Plasmodium falciparum during pregnancy can lead to severe complications for both mother and child, resulting from the cytoadhesion of parasitized erythrocytes in the intervillous space of the placenta. Cytoadherence is conferred by the specific interaction...

  19. Audit of efficacy of CoartemTM to clear plasmodium falciparum ...

    African Journals Online (AJOL)

    Background; A study, which included a follow-up study, was undertaken to assess the efficacy of CoartemTM tablets (20 mg artemether and 120 mg lumefantrine – Novartis South Africa (Pty) Ltd) to clear plasmodium falciparum malaria parasitaemia at a single 42-day follow-up, with 42 days being chosen in order to detect ...

  20. Observations on the periodicity of Plasmodium falciparum gametocytes in natural human infections

    DEFF Research Database (Denmark)

    Magesa, S M; Mdira, Y K; Akida, J A

    2000-01-01

    The circadian periodicity of Plasmodium falciparum gametocytes in peripheral blood was analysed in a group of children from an holoendemic community of north-eastern Tanzania. No periodicity was observed with asexual stage parasites. Gametocytes were shown to display a diurnal subperiodic pattern...

  1. Development and evaluation of a multiplex screening assay for Plasmodium falciparum exposure

    DEFF Research Database (Denmark)

    Jepsen, Micha Phill Grønholm; Röser, Dennis; Christiansen, Michael

    2012-01-01

    performance of a multiplex assay for detection of antibodies against Plasmodium falciparum in donor blood using IFAT as a comparator. A multiplex assay (MPA) containing the antigens GLURP-R0, GLURP-R2, MSP3, MSP1 hybrid and AMA1 was constructed using xMAP® technology. A discrimination index for exposure to P...

  2. Ingested human insulin inhibits the mosquito NF-¿B-dependent immune response to Plasmodium falciparum

    Science.gov (United States)

    We showed previously that ingested human insulin activates the insulin/IGF-1 signaling pathway in Anopheles stephensi and increases the susceptibility of these mosquitoes to Plasmodium falciparum. In other organisms insulin can alter immune responsiveness through regulation of NF-kB transcription fa...

  3. Immunoglobulin M and G antibody responses to Plasmodium falciparum glutamate-rich protein

    DEFF Research Database (Denmark)

    Dziegiel, M; Rowe, P; Bennett, S

    1993-01-01

    The aims of the present study were to describe the age-related immunoglobulin M (IgM) and IgG response to part of a 220-kDa glutamate-rich protein (GLURP) from Plasmodium falciparum and to determine possible correlations of possession of these antibodies with malaria morbidity. IgM and IgG levels...

  4. Expression of a type B RIFIN in Plasmodium falciparum merozoites and gametes

    DEFF Research Database (Denmark)

    Mwakalinga, Steven B; Wang, Christian W; Bengtsson, Dominique C

    2012-01-01

    ABSTRACT: BACKGROUND: The ability of Plasmodium falciparum to undergo antigenic variation, by switching expression among protein variants encoded by multigene families, such as var, rif and stevor, is key to the survival of this parasite in the human host. The RIFIN protein family can be divided...

  5. Plasmodium falciparum Erythrocyte Membrane Protein 1 Diversity in Seven Genomes – Divide and Conquer

    DEFF Research Database (Denmark)

    Rask, Thomas Salhøj; Hansen, Daniel Aaen; Theander, Thor G.

    2010-01-01

    The var gene encoded hyper-variable Plasmodium falciparum erythrocyte membrane protein 1 (PfEMP1) family mediates cytoadhesion of infected erythrocytes to human endothelium. Antibodies blocking cytoadhesion are important mediators of malaria immunity acquired by endemic populations. The development...

  6. High prevalence of Plasmodium falciparum pfcrt K76T mutation in ...

    African Journals Online (AJOL)

    The high prevalence of sickle cell disease (SCD) and trait in Sub-Saharan Africa coincides with the distribution of Plasmodium falciparum malaria. Due to prolonged heavy use of chloroquine (CQ) as an antimalarial, drug resistance has developed. Many countries including Tanzania abandoned the use of CQ for ...

  7. High-throughput tri-colour flow cytometry technique to assess Plasmodium falciparum parasitaemia in bioassays

    DEFF Research Database (Denmark)

    Tiendrebeogo, Regis W; Adu, Bright; Singh, Susheel K

    2014-01-01

    distinction of early ring stages of Plasmodium falciparum from uninfected red blood cells (uRBC) remains a challenge. METHODS: Here, a high-throughput, three-parameter (tri-colour) flow cytometry technique based on mitotracker red dye, the nucleic acid dye coriphosphine O (CPO) and the leucocyte marker CD45...

  8. Plasmodium falciparum mutant haplotype infection during pregnancy associated with reduced birthweight, Tanzania

    DEFF Research Database (Denmark)

    Minja, Daniel T R; Schmiegelow, Christentze; Mmbando, Bruno

    2013-01-01

    Intermittent preventive treatment during pregnancy with sulfadoxine-pyrimethamine (IPTp-SP) is a key strategy in the control of pregnancy-associated malaria. However, this strategy is compromised by widespread drug resistance from single-nucleotide polymorphisms in the Plasmodium falciparum...

  9. A simple and fast method to exclude high Plasmodium falciparum parasitaemia in travellers with imported malaria

    NARCIS (Netherlands)

    T. van Gool (Tom); M.E. van Wolfswinkel (Marlies); R. Koelewijn (Rob); P.P.A.M. van Thiel (Pieter); J. Jacobs (Jan); J.J. van Hellemond (Jaap); P.J.J. van Genderen (Perry)

    2011-01-01

    textabstractBackground: Counts of malaria parasites in peripheral blood are important to assess severity of Plasmodium falciparum malaria. Thin and thick smears are routinely used for this purpose. Methods. In this study the Binax NOW® Malaria Test, an easy-to-perform rapid diagnostic test, with

  10. Anti-Plasmodium falciparum invasion ligand antibodies in a low malaria transmission region, Loreto, Peru

    DEFF Research Database (Denmark)

    Villasis, Elizabeth; Lopez-Perez, Mary; Torres, Katherine

    2012-01-01

    Background: Erythrocyte invasion by Plasmodium falciparum is a complex process that involves two families; Erythrocyte Binding-Like (EBL) and the Reticulocyte Binding-Like (PfRh) proteins. Antibodies that inhibit merozoite attachment and invasion are believed to be important in mediating naturall...

  11. Sequential, ordered acquisition of antibodies to Plasmodium falciparum erythrocyte membrane protein 1 domains

    DEFF Research Database (Denmark)

    Cham, Gerald K K; Turner, Louise; Lusingu, John

    2009-01-01

    The binding of erythrocytes infected with mature blood stage parasites to the vascular bed is key to the pathogenesis of malignant malaria. The binding is mediated by members of Plasmodium falciparum erythrocyte membrane protein 1 (PfEMP1) family. PfEMP1s can be divided into groups, and it has...

  12. Expression of Plasmodium falciparum erythrocyte membrane protein 1 in experimentally infected humans

    DEFF Research Database (Denmark)

    Lavstsen, Thomas; Magistrado, Pamela; Hermsen, Cornelus C

    2005-01-01

    -encoded Plasmodium falciparum erythrocyte membrane protein 1 (PfEMP1) family, which is expressed on the surface of infected erythrocytes where it mediates binding to endothelial receptors. Thus, severe malaria may be caused by parasites expressing PfEMP1 variants that afford parasites optimal sequestration...

  13. Protein export marks the early phase of gametocytogenesis of the human malaria parasite Plasmodium falciparum.

    NARCIS (Netherlands)

    Silvestrini, F.; Lasonder, E.; Olivieri, A.; Camarda, G.; Schaijk, B.C.L. van; Sanchez, M.; Younis Younis, S.; Sauerwein, R.W.; Alano, P.

    2010-01-01

    Despite over a century of study of malaria parasites, parts of the Plasmodium falciparum life cycle remain virtually unknown. One of these is the early gametocyte stage, a round shaped cell morphologically similar to an asexual trophozoite in which major cellular transformations ensure subsequent

  14. Kinetics of B Cell responses to Plasmodium falciparum erythrocyte membrane protein 1 in Ghanaian women naturally exposed to malaria parasites

    DEFF Research Database (Denmark)

    Ampomah, Paulina; Stevenson, Liz; Ofori, Michael F

    2014-01-01

    confirmed earlier reports of high atypical memory B cell frequencies among residents of P. falciparum-endemic areas, and indicated an additional effect of pregnancy. Our study provides new knowledge regarding immunity to P. falciparum malaria and underpins efforts to develop PfEMP1-based vaccines against......Naturally acquired protective immunity to Plasmodium falciparum malaria takes years to develop. It relies mainly on Abs, particularly IgG specific for Plasmodium falciparum erythrocyte membrane protein 1 (PfEMP1) proteins on the infected erythrocyte surface. It is only partially understood why...

  15. An intricate case of multidrug resistant Plasmodium falciparum isolate imported from Cambodia.

    Science.gov (United States)

    Dell'Acqua, Raffaele; Fabrizio, Claudia; Di Gennaro, Francesco; Lo Caputo, Sergio; Saracino, Annalisa; Menegon, Michela; L'Episcopia, Mariangela; Severini, Carlo; Monno, Laura; Castelli, Francesco; Angarano, Gioacchino

    2017-04-14

    Imported cases of multidrug resistant Plasmodium falciparum and treatment failure with artemisinin-based regimens, although rare, have been described also in Western countries and their management is often challenging. This is also due to an inadequate knowledge and implementation of health prevention measures. A complex case of imported malaria caused by Plasmodium vivax/P. falciparum isolates in a patient who was not taking chemoprophylaxis while he was travelling in Cambodia is reported in this article. After failures of artemisinin-based and both oral and intravenous quinine-based regimens, a multidrug resistant P. falciparum was detected. The patient was successfully treated with atovaquone-proguanil. This experience highlights the importance of a careful management that should be based not only on the most up-to-date guidelines, but also on the awareness of a rapidly evolving scenario.

  16. Rarity of Mixed Species Malaria with Plasmodium falciparum and Plasmodium malariae in Travelers to Saarland in Germany.

    Science.gov (United States)

    Yayan, Josef; Rasche, Kurt

    2017-01-01

    Malaria is an acute, life-threatening infectious disease that spreads in tropical and subtropical regions. Malaria is mainly brought over to Germany by travelers, so the disease can be overlooked due to its nonspecific symptoms and a lack of experience of attending physicians. The aim of this study was to analyze, retrospectively, epidemiological and clinical data from patients examined for malaria. Patient data were collected from hospital charts at the Department of Internal Medicine, Saarland University Medical Center, Germany, for the period of 2004-2012. The data of patients with and without malaria were compared in terms of their epidemiological, demographic, clinical, and medical treatment aspects. We identified found 15 patients with malaria (28.3 %, mean age 42.3 ± 16.5 years, three females [20 %]; 95 % confidence interval of 0.2-0.4) out of the 53 patients examined. Mainly locals brought malaria over to Homburg, Germany (p = 0.009). Malaria tropica was the most common species (p < 0.0001). One patient (6.7 %) with malaria, who had recently traveled, had a mixed infection of Plasmodium falciparum and Plasmodium malariae (p = 0.670). Malaria is characterized by thrombocytopenia (p = 0.047) and elevated C-reactive protein (p = 0.019) in serum, and fever is the leading symptom (p = 0.031). In most cases, malaria was brought from Ghana (33.3 %). Further, patients had contracted malaria despite malaria prophylaxis (33.3 %, p = 0.670). In conclusion, malaria test should be used in patients with fever after a journey from Africa. Malaria caused by Plasmodium falciparum is the most common species of brought over malaria. Mixed-species Plasmodium falciparum and Plasmodium malariae are uncommon in travelers with malaria.

  17. Investigating the Roles of the C-Terminal Domain of Plasmodium falciparum GyrA.

    Directory of Open Access Journals (Sweden)

    Soshichiro Nagano

    Full Text Available Malaria remains as one of the most deadly diseases in developing countries. The Plasmodium causative agents of human malaria such as Plasmodium falciparum possess an organelle, the apicoplast, which is the result of secondary endosymbiosis and retains its own circular DNA. A type II topoisomerase, DNA gyrase, is present in the apicoplast. In prokaryotes this enzyme is a proven, effective target for antibacterial agents, and its discovery in P. falciparum opens up the prospect of exploiting it as a drug target. Basic characterisation of P. falciparum gyrase is important because there are significant sequence differences between it and the prokaryotic enzyme. However, it has proved difficult to obtain soluble protein. Here we have predicted a new domain boundary in P. falciparum GyrA that corresponds to the C-terminal domain of prokaryotic GyrA and successfully purified it in a soluble form. Biochemical analyses revealed many similarities between the C-terminal domains of GyrA from E. coli and P. falciparum, suggesting that despite its considerably larger size, the malarial protein carries out a similar DNA wrapping function. Removal of a unique Asn-rich region in the P. falciparum protein did not result in a significant change, suggesting it is dispensable for DNA wrapping.

  18. Stool microbiota composition is associated with the prospective risk of Plasmodium falciparum infection.

    Science.gov (United States)

    Yooseph, Shibu; Kirkness, Ewen F; Tran, Tuan M; Harkins, Derek M; Jones, Marcus B; Torralba, Manolito G; O'Connell, Elise; Nutman, Thomas B; Doumbo, Safiatou; Doumbo, Ogobara K; Traore, Boubacar; Crompton, Peter D; Nelson, Karen E

    2015-08-22

    In humans it is unknown if the composition of the gut microbiota alters the risk of Plasmodium falciparum infection or the risk of developing febrile malaria once P. falciparum infection is established. Here we collected stool samples from a cohort composed of 195 Malian children and adults just prior to an intense P. falciparum transmission season. We assayed these samples using massively parallel sequencing of the 16S ribosomal RNA gene to identify the composition of the gut bacterial communities in these individuals. During the ensuing 6-month P. falciparum transmission season we examined the relationship between the stool microbiota composition of individuals in this cohort and their prospective risk of both P. falciparum infection and febrile malaria. Consistent with prior studies, stool microbial diversity in the present cohort increased with age, although the overall microbiota profile was distinct from cohorts in other regions of Africa, Asia and North America. Age-adjusted Cox regression analysis revealed a significant association between microbiota composition and the prospective risk of P. falciparum infection; however, no relationship was observed between microbiota composition and the risk of developing febrile malaria once P. falciparum infection was established. These findings underscore the diversity of gut microbiota across geographic regions, and suggest that strategic modulation of gut microbiota composition could decrease the risk of P. falciparum infection in malaria-endemic areas, potentially as an adjunct to partially effective malaria vaccines.

  19. Plasmodium falciparum EPCR-binding PfEMP1 expression increases with malaria disease severity and is elevated in retinopathy negative cerebral malaria

    DEFF Research Database (Denmark)

    Shabani, Estela; Hanisch, Benjamin; Opoka, Robert O.

    2017-01-01

    Background: Expression of group A and the A-like subset of group B Plasmodium falciparum erythrocyte membrane protein 1 (PfEMP1) is associated with severe malaria (SM). The diversity of var sequences combined with the challenges of distinct classification of patient pathologies has made studying...... and especially CM as discriminated by retinopathy. Methods: We performed qRT-PCR targeting the different subsets of these var genes on samples from Ugandan children with CM (n = 98, of whom 50 had malarial retinopathy [RP] and 47 did not [RN]), severe malarial anemia (SMA, n = 47), and asymptomatic parasitemia...

  20. Plasmodium falciparum malaria in children at a tertiary teaching ...

    African Journals Online (AJOL)

    raoul

    2011-09-06

    Sep 6, 2011 ... study was done to determine the association between ABO phenotypes and the severity of P. falciparum malaria in children. Methods: ... falciparum malaria, and their mean haemoglobin was 4.49 g/dl (SD ±1.69). .... Tube 1 - 1 volume anti-A serum and 1 volume 5% patient's red cell suspension in saline.

  1. Plasmodium falciparum malaria resistance to chloroquine in five ...

    African Journals Online (AJOL)

    Chloroquine is still a first-line antimalarial drug in uncomplicated falciparum malaria. Increasing resistance to chloroquine has been reported in many parts of Nigeria. Clinical and parasitological responses and classes of resistance to chloroquine in falciparum malaria in five communities in Delta region, southern Nigeria ...

  2. Blockage of spontaneous Ca2+ oscillation causes cell death in intraerythrocitic Plasmodium falciparum.

    Directory of Open Access Journals (Sweden)

    Masahiro Enomoto

    Full Text Available Malaria remains one of the world's most important infectious diseases and is responsible for enormous mortality and morbidity. Resistance to antimalarial drugs is a challenging problem in malaria control. Clinical malaria is associated with the proliferation and development of Plasmodium parasites in human erythrocytes. Especially, the development into the mature forms (trophozoite and schizont of Plasmodium falciparum (P. falciparum causes severe malaria symptoms due to a distinctive property, sequestration which is not shared by any other human malaria. Ca(2+ is well known to be a highly versatile intracellular messenger that regulates many different cellular processes. Cytosolic Ca(2+ increases evoked by extracellular stimuli are often observed in the form of oscillating Ca(2+ spikes (Ca(2+ oscillation in eukaryotic cells. However, in lower eukaryotic and plant cells the physiological roles and the molecular mechanisms of Ca(2+ oscillation are poorly understood. Here, we showed the observation of the inositol 1,4,5-trisphospate (IP(3-dependent spontaneous Ca(2+ oscillation in P. falciparum without any exogenous extracellular stimulation by using live cell fluorescence Ca(2+ imaging. Intraerythrocytic P. falciparum exhibited stage-specific Ca(2+ oscillations in ring form and trophozoite stages which were blocked by IP(3 receptor inhibitor, 2-aminoethyl diphenylborinate (2-APB. Analyses of parasitaemia and parasite size and electron micrograph of 2-APB-treated P. falciparum revealed that 2-APB severely obstructed the intraerythrocytic maturation, resulting in cell death of the parasites. Furthermore, we confirmed the similar lethal effect of 2-APB on the chloroquine-resistant strain of P. falciparum. To our best knowledge, we for the first time showed the existence of the spontaneous Ca(2+ oscillation in Plasmodium species and clearly demonstrated that IP(3-dependent spontaneous Ca(2+ oscillation in P. falciparum is critical for the development

  3. Two Plasmodium falciparum genes express merozoite proteins that are related to Plasmodium vivax and Plasmodium yoelii adhesive proteins involved in host cell selection and invasion

    Science.gov (United States)

    Rayner, Julian C.; Galinski, Mary R.; Ingravallo, Paul; Barnwell, John W.

    2000-01-01

    Two related Plasmodium falciparum genes and their encoded proteins have been identified by comparative analyses with Plasmodium vivax reticulocyte binding protein 2 (PvRBP-2). The P. falciparum genes have a structure which suggests that they may be the result of an evolutionary duplication event, as they share more than 8 kb of closely related nucleotide sequence but then have quite divergent unique 3′ ends. Between these shared and unique regions is a complex set of repeats, the nature and number of which differs between the two genes, as well as between different P. falciparum strains. Both genes encode large hydrophilic proteins, which are concentrated at the invasive apical end of the merozoite and are predicted to be more than 350 kDa, with an N-terminal signal sequence and a single transmembrane domain near their C termini. Importantly, they also share gene structure and amino acid homology with the Plasmodium yoelii 235-kDa rhoptry protein family, which is also related to PvRBP-2. Together these Plasmodium proteins define an extended family of proteins that appear to function in erythrocyte selection and invasion. As such, they may prove to be essential components of malaria vaccine preparations. PMID:10920203

  4. Demographic and clinical profiles of Plasmodium falciparum and Plasmodium vivax patients at a tertiary care centre in southwestern India.

    Science.gov (United States)

    Chery, Laura; Maki, Jennifer N; Mascarenhas, Anjali; Walke, Jayashri T; Gawas, Pooja; Almeida, Anvily; Fernandes, Mezia; Vaz, Marina; Ramanan, Rakesh; Shirodkar, Diksha; Bernabeu, Maria; Manoharan, Suresh Kumar; Pereira, Ligia; Dash, Rashmi; Sharma, Ambika; Shaik, Riaz Basha; Chakrabarti, Rimi; Babar, Prasad; White, John; Mudeppa, Devaraja G; Kumar, Shiva; Zuo, Wenyun; Skillman, Kristen M; Kanjee, Usheer; Lim, Caeul; Shaw-Saliba, Kathryn; Kumar, Ashwani; Valecha, Neena; Jindal, V N; Khandeparkar, Anar; Naik, Pradeep; Amonkar, Sunanda; Duraisingh, Manoj T; Tuljapurkar, Shripad; Smith, Joseph D; Dubhashi, Nagesh; Pinto, Roque G W; Silveria, Maria; Gomes, Edwin; Rathod, Pradipsinh K

    2016-11-25

    Malaria remains an important cause of morbidity and mortality in India. Though many comprehensive studies have been carried out in Africa and Southeast Asia to characterize and examine determinants of Plasmodium falciparum and Plasmodium vivax malaria pathogenesis, fewer have been conducted in India. A prospective study of malaria-positive individuals was conducted at Goa Medical College and Hospital (GMC) from 2012 to 2015 to identify demographic, diagnostic and clinical indicators associated with P. falciparum and P. vivax infection on univariate analysis. Between 2012 and 2015, 74,571 febrile individuals, 6287 (8.4%) of whom were malaria positive, presented to GMC. The total number of malaria cases at GMC increased more than two-fold over four years, with both P. vivax and P. falciparum cases present year-round. Some 1116 malaria-positive individuals (mean age = 27, 91% male), 88.2% of whom were born outside of Goa and 51% of whom were construction workers, were enroled in the study. Of 1088 confirmed malaria-positive patients, 77.0% had P. vivax, 21.0% had P. falciparum and 2.0% had mixed malaria. Patients over 40 years of age and with P. falciparum infection were significantly (p < 0.001) more likely to be hospitalised than younger and P. vivax patients, respectively. While approximately equal percentages of hospitalised P. falciparum (76.6%) and P. vivax (78.9%) cases presented with at least one WHO severity indicator, a greater percentage of P. falciparum inpatients presented with at least two (43.9%, p < 0.05) and at least three (29.9%, p < 0.01) severity features. There were six deaths among the 182 hospitalised malaria positive patients, all of whom had P. falciparum. During the four year study period at GMC, the number of malaria cases increased substantially and the greatest burden of severe disease was contributed by P. falciparum.

  5. Genetic evidence for contribution of human dispersal to the genetic diversity of EBA-175 in Plasmodium falciparum.

    Science.gov (United States)

    Yasukochi, Yoshiki; Naka, Izumi; Patarapotikul, Jintana; Hananantachai, Hathairad; Ohashi, Jun

    2015-08-01

    The 175-kDa erythrocyte binding antigen (EBA-175) of Plasmodium falciparum plays a crucial role in merozoite invasion into human erythrocytes. EBA-175 is believed to have been under diversifying selection; however, there have been no studies investigating the effect of dispersal of humans out of Africa on the genetic variation of EBA-175 in P. falciparum. The PCR-direct sequencing was performed for a part of the eba-175 gene (regions II and III) using DNA samples obtained from Thai patients infected with P. falciparum. The divergence times for the P. falciparum eba-175 alleles were estimated assuming that P. falciparum/Plasmodium reichenowi divergence occurred 6 million years ago (MYA). To examine the possibility of diversifying selection, nonsynonymous and synonymous substitution rates for Plasmodium species were also estimated. A total of 32 eba-175 alleles were identified from 131 Thai P. falciparum isolates. Their estimated divergence time was 0.13-0.14 MYA, before the exodus of humans from Africa. A phylogenetic tree for a large sequence dataset of P. falciparum eba-175 alleles from across the world showed the presence of a basal Asian-specific cluster for all P. falciparum sequences. A markedly more nonsynonymous substitutions than synonymous substitutions in region II in P. falciparum was also detected, but not within Plasmodium species parasitizing African apes, suggesting that diversifying selection has acted specifically on P. falciparum eba-175. Plasmodium falciparum eba-175 genetic diversity appeared to increase following the exodus of Asian ancestors from Africa. Diversifying selection may have played an important role in the diversification of eba-175 allelic lineages. The present results suggest that the dispersals of humans out of Africa influenced significantly the molecular evolution of P. falciparum EBA-175.

  6. Increased prevalence of Plasmodium falciparum malaria in Honduras, Central America Aumento de la prevalencia de malaria por Plasmodium falciparum en Honduras, Centroamerica

    Directory of Open Access Journals (Sweden)

    Carol J. Palmer

    1998-07-01

    Full Text Available We report on our investigation of a malaria outbreak in Honduras, Central America, in January 1997. We tested 202 patients with fever and chills using thin and thick blood film microscopy. Sixteen patients lived in the city and the rest lived in rural areas. A total of 95 samples (47% were positive for malaria parasites. Seventy-nine percent (63/80 of the rural patients were infected with Plasmodium vivax and 21% (17/80 were infected with P. falciparum. In the urban area, all 15 infected patients had P. vivax malaria and none showed evidence of P. falciparum. Since previous reports indicate that falciparum malaria accounts for only 2% of the overall malaria infections in Honduras, the results reported here suggest that there is a dramatic increase in falciparum malaria in the area of Honduras investigated in this study.Notificamos los resultados de un estudio de un brote de malaria que se produjo en Honduras, Centroamérica, en enero de 1997. Sometimos a examen microscópico frotis delgados y frotis gruesos de la sangre de 202 pacientes con fiebre y escalofríos. Dieciséis pacientes eran habitantes de la zona urbana y el resto de la zona rural. Un total de 95 especímenes (47% fueron positivos a parásitos de la malaria. Setenta y ocho por ciento (62/80 de los pacientes del área rural estaban infestados con Plasmodium vivax y 22% (17/80 con P. falciparum. En la zona urbana, todos los 15 pacientes que estaban infestados tenían P. vivax y en ninguno se detectó P. falciparum. Ya que según informes previos la malaria de tipo falciparum representa solamente 2% de todos los casos de malaria en Honduras, nuestros resultados sugieren que hay un gran incremento del número de casos de malaria falciparum en la zona de Honduras en que se llevó a cabo esta investigación.

  7. Detection of antibodies to variant antigens on Plasmodium falciparum-infected erythrocytes by flow cytometry

    DEFF Research Database (Denmark)

    Staalsoe, T; Giha, H A; Dodoo, D

    1999-01-01

    BACKGROUND: Naturally induced antibodies binding to surface antigens of Plasmodium falciparum-infected erythrocytes can be detected by direct agglutination of infected erythrocytes or by indirect immunofluorescence on intact, unfixed, infected erythrocytes. Agglutinating antibodies have previously...

  8. Molecular Dissection of the Human Antibody Response to the Structural Repeat Epitope of Plasmodium falciparum sporozoite from a Protected Donor

    National Research Council Canada - National Science Library

    Chappel, Jonathan A; Rogers, William O; Hoffman, Stephen L; Kang, Angray S

    2004-01-01

    The circumsporozoite surface protein is the primary target of human antibodies against Plasmodium falciparum sporozoites, these antibodies are predominantly directed to the major repetitive epitope (Asn-Pro-Asn-Ala)n, (NPNA)n...

  9. Targeting a Novel Plasmodium falciparum Purine Recycling Pathway with Specific Immucillins

    Energy Technology Data Exchange (ETDEWEB)

    Ting, L; Shi, W; Lewandowicz, A; Singh, V; Mwakingwe, A; Birck, M R; Taylor Ringia, E A; Bench, G; Madrid, D C; Tyler, P C; Evans, G B; Furneaux, R H; Schramm, V L; Kim, K

    2004-05-19

    Plasmodium falciparum is unable to synthesize purine bases and relies upon purine salvage and purine recycling to meet its purine needs. We report that purines formed as products of the polyamine pathway are recycled in a novel pathway in which 5'-methylthioinosine is generated by adenosine deaminase. The action of P. falciparum purine nucleoside phosphorylase is a convergent step of purine salvage, converting both 5'-methylthioinosine and inosine to hypoxanthine. We used accelerator mass spectrometry to verify that 5'-methylthioinosine is an active nucleic acid precursor in P. falciparum. Prior studies have shown that inhibitors of purine salvage enzymes kill malaria, but potent malaria-specific inhibitors of these enzymes have not previously been described. 5'-methylthio-Immucillin-H, a transition state analogue inhibitor that is selective for malarial over human purine nucleoside phosphorylase, kills P. falciparum in culture. Immucillins are currently in clinical trials for other indications and may have application as antimalarials.

  10. DNA secondary structures are associated with recombination in major Plasmodium falciparum variable surface antigen gene families

    DEFF Research Database (Denmark)

    Sander, Adam F.; Lavstsen, Thomas; Rask, Thomas Salhøj

    2014-01-01

    -wide recombination hotspots in var genes, we show that during the parasite’s sexual stages, ectopic recombination between isogenous var paralogs occurs near low folding free energy DNA 50-mers and that these sequences are heavily concentrated at the boundaries of regions encoding individual Plasmodium falciparum...... falciparum-erythrocyte membrane protein 1 class on the infected erythrocyte surface. Recombination clearly generates var diversity, but the nature and control of the genetic exchanges involved remain unclear. By experimental and bioinformatic identification of recombination events and genome...... of recombination during DNA replication in P. falciparum sexual stages, and that these DSS-regulated genetic exchanges generate functional and diverse P. falciparum adhesion antigens. DSS-induced recombination may represent a common mechanism for optimizing the evolvability of virulence gene families in pathogens....

  11. A simple and fast method to exclude high Plasmodium falciparum parasitaemia in travellers with imported malaria.

    Science.gov (United States)

    van Gool, Tom; van Wolfswinkel, Marlies E; Koelewijn, Rob; van Thiel, Pieter P A M; Jacobs, Jan; van Hellemond, Jaap J; van Genderen, Perry J J

    2011-10-14

    Counts of malaria parasites in peripheral blood are important to assess severity of Plasmodium falciparum malaria. Thin and thick smears are routinely used for this purpose. In this study the Binax NOW Malaria Test, an easy-to-perform rapid diagnostic test, with Histidine Rich Protein-2 (HRP-2) and aldolase as diagnostic markers, was used for semi-quantitative assessment of parasitaemia of P. falciparum. In 257 patients with imported P. falciparum malaria, reactivity of aldolase increased with higher parasitaemia. In all patients with a parasitaemia above 50,000 asexual parasites/μl (> 1%) co-reactivity of HRP-2 and aldolase was observed. Absence of aldolase reactivity in the presence of HRP-2 was a reliable predictive marker to exclude high (> 1%) parasitaemia in P. falciparum malaria. Assessment of HRP-2 and aldolase co-reactivity can be of help in clinical decision making in the acute care setting of returning travellers suspected of having malaria.

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

    Directory of Open Access Journals (Sweden)

    Mark P Nelder

    Full Text Available 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.

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

    Science.gov (United States)

    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.

  14. Antimalarial activity of Evolvulus alsinoids Linn.-an in vitro Plasmodium falciparum specific lactate dehydrogenase enzyme inhibition assay

    OpenAIRE

    Neeraj Sethiya; Priyadarshan Keluskar; Sanjay Ingle; Shrihari Mishra

    2014-01-01

    Objective: To investigate the effect of standardized methanol extract of Evolvulus alsinoids Linn. (E. alsinoids) on Plasmodium falciparum specific lactate dehydrogenase (PfLDH) enzyme inhibition. Methods: To carry out enzyme inhibition studies, lactate dehydrogenase was cloned from Plasmodium falciparum 3D7 strain using expression vector pET28a and expressed in Escherichia coli BL21 (DE3). Protein purification was carried out by Ni-affinity chromatography. This protein was ...

  15. Inhibition of Plasmodium falciparum cysteine proteases by the sugarcane cystatin CaneCPI-4.

    Science.gov (United States)

    Melo, Pollyana M S; El Chamy Maluf, Sarah; Azevedo, Mauro F; Paschoalin, Thaysa; Budu, Alexandre; Bagnaresi, Piero; Henrique-Silva, Flávio; Soares-Costa, Andrea; Gazarini, Marcos L; Carmona, Adriana K

    2017-12-27

    Malaria is a disease caused by Plasmodium parasites that affects hundreds of millions of people. Plasmodium proteases are involved in invasion, erythrocyte egress and degradation of host proteins. Falcipains are well-studied cysteine peptidases located in P. falciparum food vacuoles that participate in hemoglobin degradation. Cystatins are natural cysteine protease inhibitors that are implicated in a wide range of regulatory processes. Here, we report that a cystatin from sugarcane, CaneCPI-4, is selectively internalized into P. falciparum infected erythrocytes and is not processed by the parasite proteolytic machinery. Furthermore, we demonstrated the inhibition of P. falciparum cysteine proteases by CaneCPI-4, suggesting that it can exert inhibitory functions inside the parasites. The inhibition of the proteolytic activity of parasite cells is specific to this cystatin, as the addition of an anti-CaneCPI-4 antibody completely abolished the inhibition. We extended the studies to recombinant falcipain-2 and falcipain-3 and demonstrated that CaneCPI-4 strongly inhibits these enzymes, with IC50 values of 12nM and 42nM, respectively. We also demonstrated that CaneCPI-4 decreased the hemozoin formation in the parasites, affecting the parasitemia. Taken together, this study identified a natural molecule as a potential antimalarial that specifically targets falcipains and also contributes to a better understanding of macromolecule acquisition by Plasmodium falciparum infected RBCs. Copyright © 2018 Elsevier B.V. All rights reserved.

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

    DEFF Research Database (Denmark)

    Jespersen, Jakob S.; Wang, Christian W.; Mkumbaye, Sixbert I.

    2016-01-01

    Most severe Plasmodium falciparum infections are experienced by young children. Severe symptoms are precipitated by vascular sequestration of parasites expressing a particular subset of the polymorphic P. falciparum erythrocyte membrane protein 1 (PfEMP1) adhesion molecules. Parasites binding hum...

  17. Biochemical characterization, localization and immunostimulating properties of a soluble glycoprotein, Ag1, isolated from in vitro cultures of Plasmodium falciparum

    DEFF Research Database (Denmark)

    Jakobsen, P H; Jepsen, S; Riley, E M

    1990-01-01

    The soluble amphiphilic glycoprotein, Ag1 (gp60), purified from supernatants of in vitro cultures of Plasmodium falciparum has a molecular mass of 60 kDa and did not exhibit size variation in the different P. falciparum isolates tested by immunoblotting. Ag1 was shown to interact with the lectin...

  18. Limited cross-reactivity among domains of the Plasmodium falciparum clone 3D7 erythrocyte membrane protein 1 family

    DEFF Research Database (Denmark)

    Joergensen, Louise; Turner, Louise; Magistrado, Pamela

    2006-01-01

    The var gene-encoded Plasmodium falciparum erythrocyte membrane protein 1 (PfEMP1) family is responsible for antigenic variation and sequestration of infected erythrocytes during malaria. We have previously grouped the 60 PfEMP1 variants of P. falciparum clone 3D7 into groups A and B/A (category A...

  19. Immunoglobulin G antibody reactivity to a group A Plasmodium falciparum erythrocyte membrane protein 1 and protection from P. falciparum malaria

    DEFF Research Database (Denmark)

    Magistrado, Pamela A; Lusingu, John; Vestergaard, Lasse S

    2007-01-01

    where P. falciparum is endemic, parasites causing severe malaria and malaria in young children with limited immunity tend to express semiconserved PfEMP1 molecules encoded by group A var genes. Here we investigated antibody responses of Tanzanians who were 0 to 19 years old to PF11_0008, a group A Pf......Variant surface antigens (VSA) on the surface of Plasmodium falciparum-infected red blood cells play a major role in the pathogenesis of malaria and are key targets for acquired immunity. The best-characterized VSA belong to the P. falciparum erythrocyte membrane protein 1 (PfEMP1) family. In areas...... of antibodies to the PF11_0008 CIDR2beta domain was associated with reduced numbers of malaria episodes. These results indicate that homologues of PF11_0008 are present in P. falciparum field isolates and suggest that PF11_0008 CIDR2beta-reactive antibodies might be involved in protection against malaria...

  20. PfSETvs methylation of histone H3K36 represses virulence genes in Plasmodium falciparum

    DEFF Research Database (Denmark)

    Jiang, Lubin; Mu, Jianbing; Zhang, Qingfeng

    2013-01-01

    The variant antigen Plasmodium falciparum erythrocyte membrane protein 1 (PfEMP1), which is expressed on the surface of P. falciparum-infected red blood cells, is a critical virulence factor for malaria. Each parasite has 60 antigenically distinct var genes that each code for a different PfEMP1...... parasite nuclei and their expression as proteins on the surface of individual infected red blood cells. PfSETvs-dependent H3K36me3 is present along the entire gene body, including the transcription start site, to silence var genes. With low occupancy of PfSETvs at both the transcription start site of var...

  1. Study of humoral immune response in mammals immunized with Plasmodium falciparum antigenic preparations

    Directory of Open Access Journals (Sweden)

    Antonio B. Cruz Cubas

    1992-01-01

    Full Text Available Six Plasmodium falciparum protein fractions, isolated under reducing conditions, were used to immunize mice, rabbits and the squirrel monkey Saimiri sciureus. Five or seven subcutaneous injections of each antigenic preparation, in conjunction with Freund's complete or incomplete adjuvants, were administered. This led to the development of specific antibodies detected by IFAT, ELISA or immunobloting which inhibited merozoite reinvasion in in vitro P. falciparum cultures. This activity seems to be associated with rhoptry proteins contained in fractions Pf F2 and Pf F4.

  2. Antimalarial Activity of Potential Inhibitors of Plasmodium falciparum Lactate Dehydrogenase Enzyme Selected by Docking Studies

    OpenAIRE

    Penna-Coutinho, Julia; Cortopassi, Wilian Augusto; Oliveira, Aline Alves; França, Tanos Celmar Costa; Krettli, Antoniana Ursine

    2011-01-01

    The Plasmodium falciparum lactate dehydrogenase enzyme (PfLDH) has been considered as a potential molecular target for antimalarials due to this parasite's dependence on glycolysis for energy production. Because the LDH enzymes found in P. vivax, P. malariae and P. ovale (pLDH) all exhibit ∼90% identity to PfLDH, it would be desirable to have new anti-pLDH drugs, particularly ones that are effective against P. falciparum, the most virulent species of human malaria. Our present work used docki...

  3. Chronic Plasmodium falciparum infections in an area of low intensity malaria transmission in the Sudan

    DEFF Research Database (Denmark)

    Hamad, A A; El Hassan, I M; El Khalifa, A A

    2000-01-01

    Chronic Plasmodium falciparum malaria infections in a Sudanese village, in an area of seasonal and unstable malaria transmission, were monitored and genetically characterized to study the influence of persistent infection on the immunology and epidemiology of low endemicity malaria. During...... the October-December malaria season of 1996, 51 individuals out of a population of 420 had confirmed and treated P. falciparum malaria in the village of Daraweesh in eastern Sudan. In a cross-sectional survey carried out in December 1996, an additional 6 individuals were found to harbour a microscopically...

  4. Early sporogonic development in local vectors of Plasmodium falciparum in rural Cameroon

    Directory of Open Access Journals (Sweden)

    Vincent Robert

    1994-01-01

    Full Text Available In ongoing studies on experimental transmission of Plasmodium falciparum in the city of Yaounde gametocyte carriers are daily being identified among dispensary patients with malaria-like complaints. This species comprises 93 of all parasitemias and because of the selection criteria most patients have it as a recent infection. 17 of all P. falciparum-positives carry detectable gametocytes with little difference between youngsters and adults. Blood of adult carriers is taken and infection of Anopheles gambiae mosquitoes is attempted by membrane feeding; the establishment of infection is judged by the presence of oocysts.

  5. Functional analysis of Plasmodium vivax dihydrofolate reductase-thymidylate synthase genes through stable transformation of Plasmodium falciparum.

    Directory of Open Access Journals (Sweden)

    Alyson M Auliff

    Full Text Available Mechanisms of drug resistance in Plasmodium vivax have been difficult to study partially because of the difficulties in culturing the parasite in vitro. This hampers monitoring drug resistance and research to develop or evaluate new drugs. There is an urgent need for a novel method to study mechanisms of P. vivax drug resistance. In this paper we report the development and application of the first Plasmodium falciparum expression system to stably express P. vivax dhfr-ts alleles. We used the piggyBac transposition system for the rapid integration of wild-type, single mutant (117N and quadruple mutant (57L/58R/61M/117T pvdhfr-ts alleles into the P. falciparum genome. The majority (81% of the integrations occurred in non-coding regions of the genome; however, the levels of pvdhfr transcription driven by the P. falciparum dhfr promoter were not different between integrants of non-coding and coding regions. The integrated quadruple pvdhfr mutant allele was much less susceptible to antifolates than the wild-type and single mutant pvdhfr alleles. The resistance phenotype was stable without drug pressure. All the integrated clones were susceptible to the novel antifolate JPC-2067. Therefore, the piggyBac expression system provides a novel and important tool to investigate drug resistance mechanisms and gene functions in P. vivax.

  6. Functional analysis of Plasmodium vivax dihydrofolate reductase-thymidylate synthase genes through stable transformation of Plasmodium falciparum.

    Science.gov (United States)

    Auliff, Alyson M; Balu, Bharath; Chen, Nanhua; O'Neil, Michael T; Cheng, Qin; Adams, John H

    2012-01-01

    Mechanisms of drug resistance in Plasmodium vivax have been difficult to study partially because of the difficulties in culturing the parasite in vitro. This hampers monitoring drug resistance and research to develop or evaluate new drugs. There is an urgent need for a novel method to study mechanisms of P. vivax drug resistance. In this paper we report the development and application of the first Plasmodium falciparum expression system to stably express P. vivax dhfr-ts alleles. We used the piggyBac transposition system for the rapid integration of wild-type, single mutant (117N) and quadruple mutant (57L/58R/61M/117T) pvdhfr-ts alleles into the P. falciparum genome. The majority (81%) of the integrations occurred in non-coding regions of the genome; however, the levels of pvdhfr transcription driven by the P. falciparum dhfr promoter were not different between integrants of non-coding and coding regions. The integrated quadruple pvdhfr mutant allele was much less susceptible to antifolates than the wild-type and single mutant pvdhfr alleles. The resistance phenotype was stable without drug pressure. All the integrated clones were susceptible to the novel antifolate JPC-2067. Therefore, the piggyBac expression system provides a novel and important tool to investigate drug resistance mechanisms and gene functions in P. vivax.

  7. Therapeutic Efficacy of Chloroquine for the Treatment of Uncomplicated Plasmodium falciparum in Haiti after Many Decades of its Use

    Science.gov (United States)

    Okech, Bernard A.; Existe, Alexandre; Romain, Jean R.; Memnon, Gladys; Victor, Yves Saint; de Rochars, Madsen Beau; Fukuda, Mark

    2015-01-01

    Chloroquine (CQ) has been used for malaria treatment in Haiti for several decades, but reports of CQ resistance are scarce. The efficacy of CQ in patients with uncomplicated Plasmodium falciparum undergoing treatment in Haiti was evaluated. Malaria patients were enrolled, treated with CQ, and monitored over a 42-day period. The treatment outcomes were evaluated on day 28 by microscopy. The P. falciparum slide-confirmed rate was 9.5% (121 of 1,277). Malaria infection was seasonal, with peak observations between October and January; 88% (107 of 121) of patients consented to participate. Sixty patients successfully completed the 42-day follow-up, whereas 47 patients withdrew consent or were lost to follow-up. The mean parasite density declined rapidly within the first few days after treatment. Seven patients did not clear their malaria infections and were clinically asymptomatic; therefore, they were considered late parasitological failures. About 90% (95% confidence interval = 84.20–97.90) of patients had no detectable parasitemia by day 28 and remained malaria-free to day 42. Testing for recrudescence, reinfection, and CQ serum levels was not done in the seven patients, and therefore, their CQ resistance status is unresolved. CQ resistance surveillance by patient follow-up, in vitro drug sensitivity studies, and molecular markers is urgently needed in Haiti. PMID:25601993

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

    Science.gov (United States)

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

    2014-01-01

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

  9. Dihydroartemisinin-piperaquine for treating uncomplicated Plasmodium falciparum malaria

    Science.gov (United States)

    Zani, Babalwa; Gathu, Michael; Donegan, Sarah; Olliaro, Piero L; Sinclair, David

    2014-01-01

    Background The World Health Organization (WHO) recommends Artemisinin-based Combination Therapy (ACT) for treating uncomplicated Plasmodium falciparum malaria. This review aims to assist the decision-making of malaria control programmes by providing an overview of the relative effects of dihydroartemisinin-piperaquine (DHA-P) versus other recommended ACTs. Objectives To evaluate the effectiveness and safety of DHA-P compared to other ACTs for treating uncomplicated P. falciparum malaria in adults and children. Search methods We searched the Cochrane Infectious Diseases Group Specialized Register; the Cochrane Central Register of Controlled Trials (CENTRAL) published in The Cochrane Library; MEDLINE; EMBASE; LILACS, and the metaRegister of Controlled Trials (mRCT) up to July 2013. Selection criteria Randomized controlled trials comparing a three-day course of DHA-P to a three-day course of an alternative WHO recommended ACT in uncomplicated P. falciparum malaria. Data collection and analysis Two authors independently assessed trials for eligibility and risk of bias, and extracted data. We analysed primary outcomes in line with the WHO 'Protocol for assessing and monitoring antimalarial drug efficacy’ and compared drugs using risk ratios (RR) and 95% confidence intervals (CI). Secondary outcomes were effects on gametocytes, haemoglobin, and adverse events. We assessed the quality of evidence using the GRADE approach. Main results We included 27 trials, enrolling 16,382 adults and children, and conducted between 2002 and 2010. Most trials excluded infants aged less than six months and pregnant women. DHA-P versus artemether-lumefantrine In Africa, over 28 days follow-up, DHA-P is superior to artemether-lumefantrine at preventing further parasitaemia (PCR-unadjusted treatment failure: RR 0.34, 95% CI 0.30 to 0.39, nine trials, 6200 participants, high quality evidence), and although PCR-adjusted treatment failure was below 5% for both ACTs, it was consistently lower

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

    NARCIS (Netherlands)

    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.

    2015-01-01

    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

  11. Evolution of Fseg/Cseg dimorphism in region III of the Plasmodium falciparum eba-175 gene.

    Science.gov (United States)

    Yasukochi, Yoshiki; Naka, Izumi; Patarapotikul, Jintana; Hananantachai, Hathairad; Ohashi, Jun

    2017-04-01

    The 175-kDa erythrocyte binding antigen (EBA-175) of the malaria parasite Plasmodium falciparum is important for its invasion into human erythrocytes. The primary structure of eba-175 is divided into seven regions, namely I to VII. Region III contains highly divergent dimorphic segments, termed Fseg and Cseg. The allele frequencies of segmental dimorphism within a P. falciparum population have been extensively examined; however, the molecular evolution of segmental dimorphism is not well understood. A comprehensive comparison of nucleotide sequences among 32 P. falciparum eba-175 alleles identified in our previous study, two Plasmodium reichenowi, and one P. gaboni orthologous alleles obtained from the GenBank database was conducted to uncover the origin and evolutionary processes of segmental dimorphism in P. falciparum eba-175. In the eba-175 nucleotide sequence derived from a P. reichenowi CDC strain, both Fseg and Cseg were found in region III, which implies that the original eba-175 gene had both segments, and deletions of F- and C-segments generated Cseg and Fseg alleles, respectively. We also confirmed the presence of allele with Fseg and Cseg in another P. reichenowi strain (SY57), by re-mapping short reads obtained from the GenBank database. On the other hand, the segmental sequence of eba-175 ortholog in P. gaboni was quite diverged from those of the other species, suggesting that the original eba-175 dimorphism of P. falciparum can be traced back to the stem linage of P. falciparum and P. reichenowi. Our findings suggest that Fseg and Cseg alleles are derived from a single eba-175 allele containing both segments in the ancestral population of P. falciparum and P. reichenowi, and that the allelic dimorphism of eba-175 was shaped by the independent emergence of similar dimorphic lineage in different species that has never been observed in any evolutionary mode of allelic dimorphism at other loci in malaria genomes. Copyright © 2017 Elsevier B.V. All

  12. Sustained Malaria Control Over an 8-Year Period in Papua New Guinea: The Challenge of Low-Density Asymptomatic Plasmodium Infections.

    Science.gov (United States)

    Koepfli, Cristian; Ome-Kaius, Maria; Jally, Shadrach; Malau, Elisheba; Maripal, Samuel; Ginny, Jason; Timinao, Lincoln; Kattenberg, Johanna Helena; Obadia, Thomas; White, Michael; Rarau, Patricia; Senn, Nicolas; Barry, Alyssa E; Kazura, James W; Mueller, Ivo; Robinson, Leanne J

    2017-12-12

    The scale-up of effective malaria control in the last decade has resulted in a substantial decline in the incidence of clinical malaria in many countries. The effects on the proportions of asymptomatic and submicroscopic infections and on transmission potential are yet poorly understood. In Papua New Guinea, vector control has been intensified since 2008, and improved diagnosis and treatment was introduced in 2012. Cross-sectional surveys were conducted in Madang Province in 2006 (with 1280 survey participants), 2010 (with 2117 participants), and 2014 (with 2516 participants). Infections were quantified by highly sensitive quantitative polymerase chain reaction (PCR) analysis, and gametocytes were quantified by reverse-transcription qPCR analysis. Plasmodium falciparum prevalence determined by qPCR decreased from 42% in 2006 to 9% in 2014. The P. vivax prevalence decreased from 42% in 2006 to 13% in 2010 but then increased to 20% in 2014. Parasite densities decreased 5-fold from 2006 to 2010; 72% of P. falciparum and 87% of P. vivax infections were submicroscopic in 2014. Gametocyte density and positivity correlated closely with parasitemia, and population gametocyte prevalence decreased 3-fold for P. falciparum and 29% for P. vivax from 2010 to 2014. Sustained control has resulted in reduced malaria transmission potential, but an increasing proportion of gametocyte carriers are asymptomatic and submicroscopic and represent a challenge to malaria control.

  13. Spatial variation and socio-economic determinants of Plasmodium falciparum infection in northeastern Tanzania

    Directory of Open Access Journals (Sweden)

    Theander Thor G

    2011-05-01

    Full Text Available Abstract Background Malaria due to Plasmodium falciparum is the leading cause of morbidity and mortality in Tanzania. According to health statistics, malaria accounts for about 30% and 15% of hospital admissions and deaths, respectively. The risk of P. falciparum infection varies across the country. This study describes the spatial variation and socio-economic determinants of P. falciparum infection in northeastern Tanzania. Methods The study was conducted in 14 villages located in highland, lowland and urban areas of Korogwe district. Four cross-sectional malaria surveys involving individuals aged 0-19 years were conducted during short (Nov-Dec and long (May-Jun rainy seasons from November 2005 to June 2007. Household socio-economic status (SES data were collected between Jan-April 2006 and household's geographical positions were collected using hand-held geographical positioning system (GPS unit. The effects of risk factors were determined using generalized estimating equation and spatial risk of P. falciparum infection was modelled using a kernel (non-parametric method. Results There was a significant spatial variation of P. falciparum infection, and urban areas were at lower risk. Adjusting for covariates, high risk of P. falciparum infection was identified in rural areas of lowland and highland. Bed net coverage levels were independently associated with reduced risk of P. falciparum by 19.1% (95%CI: 8.9-28.2, p Conclusions There was high spatial variation of risk of P. falciparum infection and urban area was at the lowest risk. High bed net coverage, better SES and good housing were among the important risk factors associated with low risk of P. falciparum infection.

  14. Neutrophil alterations in pregnancy-associated malaria and induction of neutrophil chemotaxis by Plasmodium falciparum

    DEFF Research Database (Denmark)

    Boström, S.; Schmiegelow, C; Abu Abed, U

    2017-01-01

    Pregnancy-associated malaria (PAM) is a severe form of the disease caused by sequestration of Plasmodium falciparum-infected red blood cells (iRBCs) in the developing placenta. Pathogenesis of PAM is partially based on immunopathology, with frequent monocyte infiltration into the placenta....... Neutrophils are abundant blood cells that are essential for immune defence but may also cause inflammatory pathology. Their role in PAM remains unclear. We analysed neutrophil alterations in the context of PAM to better understand their contribution to disease development. Pregnant women exposed to Plasmodium...... falciparum had decreased numbers of circulating neutrophils. Placental-like BeWo cells stimulated with malaria parasites produced the neutrophil chemoattractant IL-8 and recruited neutrophils in a trans-well assay. Finally, immunostaining of a PAM placenta confirmed neutrophil accumulation...

  15. A semi-synthetic glycosaminoglycan analogue inhibits and reverses Plasmodium falciparum cytoadherence.

    Science.gov (United States)

    Skidmore, Mark A; Mustaffa, Khairul Mohd Fadzli; Cooper, Lynsay C; Guimond, Scott E; Yates, Edwin A; Craig, Alister G

    2017-01-01

    A feature of mature Plasmodium falciparum parasitized red blood cells is their ability to bind surface molecules of the microvascular endothelium via the parasite-derived surface protein Plasmodium falciparum erythrocyte membrane protein 1 (PfEMP1). This ligand is associated with the cytoadherence pathology observed in severe malaria. As pRBC treated with effective anti-malarial drugs are still able to cytoadhere, there is therefore a need to find an adjunct treatment that can inhibit and reverse the adhesion process. One semi-synthetic, sulfated polysaccharide has been identified that is capable of inhibiting and reversing sequestration of pRBC on endothelial cells in vitro under physiological flow conditions. Furthermore, it exhibits low toxicity in the intrinsic (APTT assay) and extrinsic (PT assay) clotting pathways, as well as exhibiting minimal effects on cell (HUVEC) viability (MTT proliferation assay). These findings suggest that carbohydrate-based anti-adhesive candidates may provide potential leads for therapeutics for severe malaria.

  16. A Bioinformatics Approach for Homology Modeling and Binding Site Identification of Triosephosphate Isomerase from Plasmodium falciparum 3D7

    OpenAIRE

    Ullah, M; Hira, J; Ghosh, T.; Ishaque, N.; Absar, N

    2012-01-01

    Malaria is a major public health concern, and malarial parasites have developed resistance against the commonly available drugs. So now a days it is a major concern to find out a new target for drug therapy. Plasmodium falciparum 3D7, one of the strains of plasmodium species also lacks in a functional tricarboxylic acid cycle and solely dependent on glycolysis for its energy supply like other plasmodium species. Although enzymes of malarial parasite have been considered as potential antimalar...

  17. Soluble haemoglobin is a marker of recent Plasmodium falciparum infections

    DEFF Research Database (Denmark)

    Jakobsen, P H; Bygbjerg, I C; Theander, T G

    1997-01-01

    . falciparum malaria compared to the levels during acute disease. Thus, both soluble Hb and haptoglobin appear to be markers of recent P. falciparum infections. Very high levels of CRP protein were measured in some of the malaria patients at the day of treatment while lower levels were recorded 7 and 30 days...... after treatment. Soluble Hb levels were associated with malariometric parameters in a similar fashion to haptoglobin. The new Mab-based assay for measuring soluble Hb in the peripheral blood of malaria patients may be useful for future epidemiological studies of malaria....

  18. Fluoxetine Hydrochloride Enhances In Vitro Susceptibility to Chloroquine in Resistant Plasmodium falciparum

    Science.gov (United States)

    1992-12-01

    directed synthesis of new antimalarial drugs. Malaria is a significant source of morbidity in the world, ity, desipramine (3) and chlorpromazine (12... Hydrochloride Enhances In Vitro Susceptibility to Chloroguine in Resistant Plasmodium falciparum 4. AUTHOR(S) Lucia Gerena, Glenn T. Bass, Sr., Dennis E. Kyle...current description of the chloroquine resistance phenotype and may provide additional insights into lead-directed synthesis of new antimalarial drugs

  19. Catechin Isolated from Garcinia celebica Leaves Inhibit Plasmodium falciparum Growth through the Induction of Oxidative Stress

    OpenAIRE

    Abdulah, Rizky; SURADJI, EKA W.; Subarnas, Anas; Supratman, Unang; Sugijanto, Milyadi; Diantini, Ajeng; Lestari, Keri; Melisa I. Barliana; Kawazu, Shinichiro; Koyama, Hiroshi

    2017-01-01

    Background: Resistance of antimalarial drugs to Plasmodium falciparum has become a major concern in malaria eradication. Although it is also affected by several socioeconomic factors, a new antiplasmodial agent is needed for a global malaria control program. Objective: In this study, we attempted to uncover the antiplasmodial properties of Garcinia celebica, an Indonesian medicinal plant, along with the responsible compound and its possible mechanism. Materials and Methods: The G. celebica le...

  20. Molecular surveillance of antimalarial drug resistance related genes in Plasmodium falciparum isolates from Eritrea.

    Science.gov (United States)

    Menegon, Michela; Nurahmed, Abduselam M; Talha, Albadawi A; Nour, Bakri Y M; Severini, Carlo

    2016-05-01

    The introduction of artemisinin-based combination therapy has led to extraordinary results in malaria control, however the recent emergence of partial resistance to artemisinin therapy in Southeast Asia jeopardizes these successes. This study aimed at investigating resistance to the antimalarial drugs by evaluating the polymorphisms in the PfK13, Pfcrt and Pfmdr1 genes in Plasmodium falciparum isolates obtained from patients in Eritrea. Copyright © 2016 Elsevier B.V. All rights reserved.

  1. Detection of telomerase activity in Plasmodium falciparum using a nonradioactive method

    Directory of Open Access Journals (Sweden)

    Rubiano Claudia C

    2003-01-01

    Full Text Available A simple, quick and sensitive method was used to detect telomerase activity in Plasmodium falciparum. The telomeric repeat amplification protocol (TRAP assay was modified using electrophoresis and staining with SYBR-green I to detect telomerase activity in a range of 10² to 10(7 parasites. This might be a useful way to ascertain telomerase activity in different types of nontumor cells.

  2. Characterization of the Small Exported Plasmodium falciparum Membrane Protein SEMP1

    OpenAIRE

    Olivier Dietz; Sebastian Rusch; Françoise Brand; Esther Mundwiler-Pachlatko; Annette Gaida; Till Voss; Hans-Peter Beck

    2014-01-01

    Survival and virulence of the human malaria parasite Plasmodium falciparum during the blood stage of infection critically depend on extensive host cell refurbishments mediated through export of numerous parasite proteins into the host cell. The parasite-derived membranous structures called Maurer's clefts (MC) play an important role in protein trafficking from the parasite to the red blood cell membrane. However, their specific function has yet to be determined. We identified and characterize...

  3. Fluorine Modulates Species Selectivity in the Triazolopyrimidine Class of Plasmodium falciparum Dihydroorotate Dehydrogenase Inhibitors

    OpenAIRE

    Deng, Xiaoyi; Kokkonda, Sreekanth; El Mazouni, Farah; White, John; Burrows, Jeremy N.; Kaminsky, Werner; Charman, Susan A.; Matthews, David; Rathod, Pradipsinh K.; Phillips, Margaret A.

    2014-01-01

    Malaria is one of the most serious global infectious diseases. The pyrimidine biosynthetic enzyme Plasmodium falciparum dihydroorotate dehydrogenase (PfDHODH) is an important target for antimalarial chemotherapy. We describe a detailed analysis of protein?ligand interactions between DHODH and a triazolopyrimidine-based inhibitor series to explore the effects of fluorine on affinity and species selectivity. We show that increasing fluorination dramatically increases binding to mammalian DHODHs...

  4. High level of resistance of Plasmodium falciparum to sulfadoxine-pyrimethamine in children in Tanzania

    DEFF Research Database (Denmark)

    Rønn, A M; Msangeni, H A; Mhina, J

    1996-01-01

    In many areas of tropical Africa affected by chloroquine-resistant Plasmodium falciparum, a combination of sulfadoxine and pyrimethamine (S-P) is used for alternative medication, especially in young children. In Magoda village in Muheza District, north-eastern Tanzania, 38 children 1-10 years of ...... intervention with weekly dapsone-pyrimethamine between May 1993 and May 1994 seems to have been the most important....

  5. Drug and Vaccine evaluation in the Human Aotus Plasmodium falciparum Model

    Science.gov (United States)

    2011-05-01

    the increasing drug resistance exhibited by the highly pathogenic Plasmodium falciparum parasites in Asia, Africa, and Latin America , and more...tested in Panamanian Aotus (11). Also, different vaccine formulations, routes and methods of administration with a comparable Hepatitis B Plasmid DNA...Immune reponse to a hepatitis B DNA vaccine in Aotus monkeys: a comparison of vaccine formulation, route, and method of administration. Mol Med. 4

  6. Effects of three compounds extracted from Morinda lucida on Plasmodium falciparum.

    Science.gov (United States)

    Koumaglo, K; Gbeassor, M; Nikabu, O; de Souza, C; Werner, W

    1992-12-01

    The effects of three compounds, digitolutein (1), rubiadin 1-methyl ether (2) and damnacanthal (3) extracted from the stem bark and the roots of Morinda lucida Benth. on the growth of Plasmodium falciparum in vitro were investigated. The number of parasites (schizonts) decreased significantly in a dose-dependent manner, and 100% of inhibition was obtained with 30 to 40 micrograms of each compound tested. The IC50 values were calculated.

  7. Impaired renal function in owl monkeys (Aotus nancymai infected with Plasmodium falciparum

    Directory of Open Access Journals (Sweden)

    R. E. Weller

    1992-01-01

    Full Text Available Impaired renal function was observed in sixteen Aotus nancymai 25 and 3 months following infection with the Uganda Palo Alto strain of Plasmodium falciparum. Decrease were noted in the clearance of endogenous creatinine, creatinine excretion, and urine volume while increases were observed in serum urea nitrogen, urine protein, urine potassium, fractional excretion of phosphorus and potassium, and activities of urinary enzymes. The results were suggestive of glomerulonephropathy and chronic renal disease.

  8. Temporal association of acute hepatitis A and Plasmodium falciparum malaria in children.

    Science.gov (United States)

    Klein Klouwenberg, Peter; Sasi, Philip; Bashraheil, Mahfudh; Awuondo, Ken; Bonten, Marc; Berkley, James; Marsh, Kevin; Borrmann, Steffen

    2011-01-01

    In sub-Saharan Africa, Plasmodium falciparum and hepatitis A (HAV) infections are common, especially in children. Co-infections with these two pathogens may therefore occur, but it is unknown if temporal clustering exists. We studied the pattern of co-infection of P. falciparum malaria and acute HAV in Kenyan children under the age of 5 years in a cohort of children presenting with uncomplicated P. falciparum malaria. HAV status was determined during a 3-month follow-up period. Among 222 cases of uncomplicated malaria, 10 patients were anti-HAV IgM positive. The incidence of HAV infections during P. falciparum malaria was 1.7 (95% CI 0.81-3.1) infections/person-year while the cumulative incidence of HAV over the 3-month follow-up period was 0.27 (95% CI 0.14-0.50) infections/person-year. Children with or without HAV co-infections had similar mean P. falciparum asexual parasite densities at presentation (31,000/µL vs. 34,000/µL, respectively), largely exceeding the pyrogenic threshold of 2,500 parasites/µL in this population and minimizing risk of over-diagnosis of malaria as an explanation. The observed temporal association between acute HAV and P. falciparum malaria suggests that co-infections of these two hepatotrophic human pathogens may result from changes in host susceptibility. Testing this hypothesis will require larger prospective studies.

  9. Identification of Plasmodium falciparum isolates lacking histidine-rich protein 2 and 3 in Eritrea.

    Science.gov (United States)

    Menegon, Michela; L'Episcopia, Mariangela; Nurahmed, Abduselam M; Talha, Albadawi A; Nour, Bakri Y M; Severini, Carlo

    2017-11-01

    The histidine-rich protein 2 of Plasmodium falciparum is the most common malaria antigen targeted by rapid diagnostic tests for the specific diagnosis of P. falciparum. Recently, pfhrp2 gene deletions have been documented in P. falciparum isolates from South America and some multiple endemic countries in Africa and Asia. Parasites with such gene deletions can produce false negative diagnostic results using HRP2-based rapid diagnostic kits. In the present work, the prevalence of P. falciparum parasites lacking pfhrp2, pfhrp3, which produces a second P. falciparum antigen that is recognized by PfHRP2 -based rapid diagnostic tests, and their flanking genes was evaluated in 135 P. falciparum isolates from Gash Barka region and in 9 isolates from Debub region, in Eritrea. In the analyzed samples, 56% (81/144) of isolates were pfhrp2/pfhrp3 positive, while 9.7% (14/144) showed deletion of exon 2 of pfhrp2 gene and 43% (62/144) of isolates lacked the pfhrp3 gene. These results suggest that the pfhrp2 and pfhrp3 deletion phenomenon is present in a considerable proportion in the study areas, thus making the HRP2/3 based rapid diagnostic tests not completely reliable for malaria diagnosis in Eritrea. Copyright © 2017 Elsevier B.V. All rights reserved.

  10. Scale up of a Plasmodium falciparum elimination program and surveillance system in Kayin State, Myanmar [version 1; referees: 2 approved

    Directory of Open Access Journals (Sweden)

    Daniel M. Parker

    2017-10-01

    Full Text Available Background: Myanmar has one of the largest malaria burdens in Southeast Asia. Along the border with Thailand, Plasmodium falciparum parasites are increasingly showing reduced sensitivity to artemisinin combination therapies. Given that there are no current alternative treatment therapies, one proposed solution to the threat of untreatable P. falciparum malaria is to eliminate the parasite from the region. Several small-scale elimination projects have been piloted along the Myanmar-Thailand border. Following their success, this operational research aimed to scale up the elimination to a broad area of Eastern Kayin State, Myanmar. Methods: The project relied on geographic reconnaissance and a geographic information system, community engagement, generalized access to community-based early diagnosis and treatment, near real-time epidemiological surveillance, cross sectional malaria prevalence surveys and targeted mass drug administration in villages with high prevalence of P. falciparum malaria. Molecular markers of drug resistance were also monitored in individuals with symptomatic and asymptomatic infections. Discussion: This project illustrates the establishment of an elimination project and operational research in a remote, rural area encompassing several armed groups, multiple political organizations and a near-absent health care infrastructure. The establishment of the project relied on a strong rapport with the target community, on-the-ground knowledge (through geographic surveys and community engagement, rapid decision making and an approach that was flexible enough to quickly adapt to a complex landscape. The elimination project is ongoing, now over three years in operation, and assessment of the impact of this operational research will follow. This project has relevance not only for other malaria elimination projects but also for operational research aimed at eliminating other diseases.

  11. Scale up of a Plasmodium falciparum elimination program and surveillance system in Kayin State, Myanmar [version 2; referees: 2 approved

    Directory of Open Access Journals (Sweden)

    Daniel M. Parker

    2017-12-01

    Full Text Available Background: Myanmar has one of the largest malaria burdens in the Greater Mekong Subregion (GMS. Throughout the GMS, Plasmodium falciparum parasites are increasingly resistant to artemisinin combination therapies. Given that there are no current alternative treatment therapies, one proposed solution to the threat of untreatable P. falciparum malaria is to eliminate the parasite from the region. Several small-scale elimination projects have been piloted in the GMS, including along the Myanmar-Thailand border. Following the success of the pilot elimination project along the Myanmar-Thailand border, there was a scale up to a broad area of Eastern Kayin State, Myanmar. Here we describe the establishment of the scale up elimination project in Easter Kayin State. Methods: The scale up relied on geographic reconnaissance and a geographic information system, community engagement, generalized access to community-based early diagnosis and treatment, near real-time epidemiological surveillance, cross sectional malaria prevalence surveys and targeted mass drug administration in villages with high prevalence of P. falciparum malaria. Molecular markers of drug resistance were also monitored in individuals with symptomatic and asymptomatic infections. Discussion: This protocol illustrates the establishment of an elimination project and operational research in a remote, rural area encompassing several armed groups, multiple political organizations and a near-absent health care infrastructure. The establishment of the project relied on a strong rapport with the target community, on-the-ground knowledge (through geographic surveys and community engagement, rapid decision making and an approach that was flexible enough to quickly adapt to a complex landscape. The elimination project is ongoing, now over three years in operation, and assessment of the impact of this operational research will follow. This project has relevance not only for other malaria elimination

  12. HUBUNGAN SENSISTIVITAS PLASMODIUM FALCIPARUM TERHADAP KOMBINASI PIRIMETAMIN/SULFADOKSIN DAN KLOROKUIN SECARA IN VITRO

    Directory of Open Access Journals (Sweden)

    Sahat Ompusunggu

    2012-09-01

    Full Text Available An in vitro sensitivity test was conducted to study the sensitivity of Plasmodium falciparum against chloroquine and pyrimethamine/sulphadoxine combination. The relationship between sensitivity of the parasite to the two drugs was also studied. A total of 72 patients from five localities were examined during 1984-1985. Test against chloroquine was conduc­ted according to WHO method, while against pyrimethamine/sulphadoxine combination, a modified method of Nguyen Dinh and Payne and Eastham and Rieckmann was used. The results showed that there is no relationship between the sensitivity of P. falciparum against pyrimethamine/ sulphadoxine combination and chloroquine. It can be concluded that in case of chloroquine resistant P. falciparum, pyrimethamine/sulphadoxine combination could be applied as an alternative chemotherapy.

  13. Cellulose filtration of blood from malaria patients for improving ex vivo growth of Plasmodium falciparum parasites

    DEFF Research Database (Denmark)

    Mkumbaye, Sixbert I; Minja, Daniel T R; Jespersen, Jakob S

    2017-01-01

    BACKGROUND: Establishing in vitro Plasmodium falciparum culture lines from patient parasite isolates can offer deeper understanding of geographic variations of drug sensitivity and mechanisms of malaria pathogenesis and immunity. Cellulose column filtration of blood is an inexpensive, rapid...... and effective method for the removal of host factors, such as leucocytes and platelets, significantly improving the purification of parasite DNA in a blood sample. METHODS: In this study, the effect of cellulose column filtration of venous blood on the initial in vitro growth of P. falciparum parasite isolates....... falciparum merozoite surface protein 2 genotyping was performed using nested PCR on extracted genomic DNA, and the var gene transcript levels were investigated, using quantitative PCR on extracted RNA, at admission and 4 days of culture. RESULTS: The cellulose-filtered parasites grew to higher parasitaemia...

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

    Science.gov (United States)

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

    2011-10-01

    Pregnant women are at increased risk of malaria, but in Angola, epidemiologic data from this group is almost inexistent. We conducted a cross-sectional study to determine the prevalence and risk factors of Plasmodium falciparum infections in 567 pregnant Angolan women living in Luanda province. One in five women had P. falciparum at delivery, diagnosed by PCR assay. Age, residence and history of malaria during pregnancy were significantly associated with P. falciparum infection, but gravidity and use of anti-malarial drugs were not. Placental infections were significantly more common in women ≤18 years old and in primigravidae, but we could not correlate placental infections with poor pregnancy outcomes. These findings are relevant to malaria control policies in Luanda, Angola. © 2011 Blackwell Publishing Ltd.

  15. Crystal Structure Analyses of the Fosmidomycin-Target Enzyme from Plasmodium Falciparum

    Science.gov (United States)

    Umeda, Tomonobu; Kusakabe, Yoshio; Tanaka, Nobutada

    The human malaria parasite Plasmodium falciparum is responsible for the death of more than a million people each year. Fosmidomycin has proved to be efficient in the treatment of P. falciparum malaria through the inhibition of 1-deoxy-D-xylulose 5-phosphate reductoisomerase (DXR), an enzyme of the non-mevalonate pathway of isoprenoid biosynthesis, which is absent in humans. Crystal structure analyses of P. falciparum DXR (PfDXR) revealed that (i) an intrinsic flexibility of the PfDXR molecule accounts for the induced-fit movement to accommodate the bound inhibitor in the active site, and (ii) a cis arrangement of the oxygen atoms of the hydroxamate group of the bound inhibitor is essential for tight binding of the inhibitor to the active site metal. We believe that our study will serve as a useful guide to develop more potent PfDXR inhibitors.

  16. A new method for culturing Plasmodium falciparum shows replication at the highest erythrocyte densities

    Science.gov (United States)

    Li, Tao; Glushakova, Svetlana; Zimmerberg, Joshua

    2003-01-01

    Plasmodium falciparum replicates poorly in erythrocyte densities greater than a hematocrit of 20%. A new method to culture the major malaria parasite was developed by using a hollow fiber bioreactor that preserves healthy erythrocytes at hematocrit up to 100%. P. falciparum replicated equally well at all densities studied. This method proved advantageous for large-scale preparation of parasitized erythrocytes (and potentially immunogens thereof), because high yields ( approximately 10(10) in 4 days) could be prepared with less cost and labor. Concomitantly, secreted proteins were concentrated by molecular sieving during culture, perhaps contributing to the parasitemic limit of 8%-12% with the 3D7 strain. The finding that P. falciparum can replicate at packed erythrocyte densities suggests that this system may be useful for study of the pathogenesis of fatal cerebral malaria, of which one feature is densely packed blood cells in brain microvasculature.

  17. Versatile control of Plasmodium falciparum gene expression with an inducible protein-RNA interaction.

    Science.gov (United States)

    Goldfless, Stephen J; Wagner, Jeffrey C; Niles, Jacquin C

    2014-11-05

    The available tools for conditional gene expression in Plasmodium falciparum are limited. Here, to enable reliable control of target gene expression, we build a system to efficiently modulate translation. We overcame several problems associated with other approaches for regulating gene expression in P. falciparum. Specifically, our system functions predictably across several native and engineered promoter contexts, and affords control over reporter and native parasite proteins irrespective of their subcellular compartmentalization. Induction and repression of gene expression are rapid, homogeneous and stable over prolonged periods. To demonstrate practical application of our system, we used it to reveal direct links between antimalarial drugs and their native parasite molecular target. This is an important outcome given the rapid spread of resistance, and intensified efforts to efficiently discover and optimize new antimalarial drugs. Overall, the studies presented highlight the utility of our system for broadly controlling gene expression and performing functional genetics in P. falciparum.

  18. Prevalence of Plasmodium falciparum in participants at selected ...

    African Journals Online (AJOL)

    ABO and Rh blood groups of the participants were also determined on the basis of agglutination method with commercially purchased monoclonal ABD antisera. Of the three hundred and five (305) participants screened (165 males and 140 females), 121 (39.7%) blood samples were positive for P. falciparum which ...

  19. In vitro EFFICACY OF ACT DRUGS ON Plasmodium falciparum ...

    African Journals Online (AJOL)

    userpc

    Resistance of P. falciparum to the common and cheap antimalarial drugs chloroquine and sulpadoxyne-pyrimethamine has a profound public health impact in malaria endemic areas like Nigeria. This increasing drug resistance has necessitated change in antimalarial therapy in. Africa. In view of this, the World Health.

  20. Metodos proteomicos aplicados al estudio de la malaria: plasmodium falciparum

    National Research Council Canada - National Science Library

    Cuesta Astroz, Yesid; Segura Latorre, Cesar

    2012-01-01

    ... a la resistencia del parasito a los antimalaricos (Vieira et al., 2004). En P. falciparum el mecanismo de resistencia a ciertos medicamentos como por ejemplo sulfadoxinapirimetamina y 4-aminoquinolinas es conocido, hay evidencia que proteinas transportadoras y proteasas estan involucradas (Vieira et al., 2004). Ademas, que bajo presion con clo...

  1. Inactivation of Plasmodium falciparum in whole body by riboflavin ...

    African Journals Online (AJOL)

    Blood was inocu- lated with 104 or 105 parasites/mL and riboflavin treated with or without ultraviolet (UV) irradiation (40-160 J/mL red blood cells [mLRBCs]). Parasite genome integrity was assessed by quantitative amplification inhibition assays, and P. falciparum viability was monitored in vitro. Results Riboflavin alone did ...

  2. Changes in Plasmodium Falciparum Population Dynamics in Two ...

    African Journals Online (AJOL)

    Population A comprised of 164 children (75 acute uncomplicated malaria (UM), 48 cerebral malaria (CM) and 41 severe malarial anaemia (SMA), while Population B comprised of 225 children (115 UM, 55 CM, 55 SMA). Results showed a high level of genetic diversity and multiplicity of P.falciparum infections in the two ...

  3. Multiple Antigen Peptide Vaccines against Plasmodium falciparum Malaria

    Science.gov (United States)

    2010-01-01

    from P. falciparum that are available in the literature , and we demonstrate their antibody and cellular responses in different MHC haplotype mice...face antigen (Pb44) protect mioe against malarial infection. J. Exp. Med. 151:1S04-1513. 41. Puentes , A., J. Garcia, R. Vera, Q. R. Lopez, M. Urquiza

  4. Drug-resistant Plasmodium falciparum malaria in the eastern ...

    African Journals Online (AJOL)

    8.SC. HONS. B. L Sharp. PHD. It should be borne in mind that more than 40% of cases are classified as imported into the eastern and northern. Transvaal provinces, of which a high percentage originate from other southern African countries where ... Materials and methods. Blood containing P. falciparum was obtained from ...

  5. Molecular markers of antifolate resistance in Plasmodium falciparum isolates from Luanda, Angola

    Science.gov (United States)

    2011-01-01

    Background Plasmodium falciparum malaria remains a leading health problem in Africa and its control is seriously challenged by drug resistance. Although resistance to the sulphadoxine-pyrimethamine (SP) is widespread, this combination remains an important component of malaria control programmes as intermittent preventive therapy (IPT) for pregnant women and children. In Angola, resistance patterns have been poorly characterized, and IPT has been employed for pregnant women since 2006. The aim of this study was to assess the prevalence of key antifolate resistance mediating polymorphisms in the pfdhfr and pfdhps genes in P. falciparum samples from Angola. Methods Plasmodium falciparum samples collected in Luanda, in 2007, were genotyped by amplification and DNA forward and reverse sequencing of the pfdhfr and pfdhps genes. Results The most prevalent polymorphisms identified were pfdhfr 108N (100%), 51I (93%), 59R (57%) and pfdhps 437G (93%). Resistance-mediating polymorphisms in pfdhps less commonly observed in West Africa were also identified (540E in 10%, 581G in 7% of samples). Conclusion This study documents an important prevalence of 4 P. falciparum polymorphisms that predicts an antifolate resistance in Luanda. Further, some samples presented additional mutations associated to high-level resistance. These results suggest that the use of SP for IPT may no longer be warranted in Angola. PMID:21864379

  6. Plasmodium Falciparum: Adhesion Phenotype of Infected Erythrocytes Using Classical and Mini-Column Cytoadherence Techniques

    Directory of Open Access Journals (Sweden)

    N Kalantari

    2013-03-01

    Full Text Available Background: Cytoadherence of Plasmodium falciparum- infected erythrocytes to host cells is an impor­tant trait for parasite survival and has a major role in pathology of malaria disease. Infections with P. falciparum usually consist of several subpopulations of parasites with different adhesive proper­ties. This study aimed to compare relative sizes of various binding subpopulations of different P. falciparum isolates. It also investigated the adhesive phenotype of a laboratory P. falciparum line, A4, using different binding techniques.Methods: Seven different P. falciparum isolates (ITG, A4, 3D7 and four field isolates were cultivated to late trophozoite and schizont and then cytoadherence to cell differentiation 36 (CD36, intercellu­lar cell adhesion molecule-1 (ICAM-1, and vascular cell adhesion molecule (V-CAM and E-selectin were examined. The relative binding sizes of parasite subpopulations to human receptors were meas­ured by mini-column cytoadherence method. The adhesion phenotype of P. falciparum-A4 line was evaluated by in vitro static, flow-based and mini-column binding assays.Results: The relative binding size of ITG, A4 and 3D7 clones to a column made with CHO/ICAM-1 was 68%, 54% and 0%, respectively. The relative binding sizes of these lines to CHO/CD36 were 59.7%, 28.7% and 0%, respectively. Different field isolates had variable sizes of respective CD36 and ICAM1-binding subpopulations. A4 line had five different subpopulations each with different binding sizes.Conclusion: This study provided further evidence that P. falciparum isolates have different binding subpopulations sizes in an infection. Furthermore, measurement of ICAM-1 or CD36 binding subpopula­tions may practical to study the cytoadherence phenotypes of P. falciparum field isolates at the molecular level.

  7. Plasmodium falciparum-like parasites infecting wild apes in southern Cameroon do not represent a recurrent source of human malaria

    Science.gov (United States)

    Sundararaman, Sesh A.; Liu, Weimin; Keele, Brandon F.; Learn, Gerald H.; Bittinger, Kyle; Mouacha, Fatima; Ahuka-Mundeke, Steve; Manske, Magnus; Sherrill-Mix, Scott; Li, Yingying; Malenke, Jordan A.; Delaporte, Eric; Laurent, Christian; Mpoudi Ngole, Eitel; Kwiatkowski, Dominic P.; Shaw, George M.; Rayner, Julian C.; Peeters, Martine; Sharp, Paul M.; Bushman, Frederic D.; Hahn, Beatrice H.

    2013-01-01

    Wild-living chimpanzees and gorillas harbor a multitude of Plasmodium species, including six of the subgenus Laverania, one of which served as the progenitor of Plasmodium falciparum. Despite the magnitude of this reservoir, it is unknown whether apes represent a source of human infections. Here, we used Plasmodium species-specific PCR, single-genome amplification, and 454 sequencing to screen humans from remote areas of southern Cameroon for ape Laverania infections. Among 1,402 blood samples, we found 1,000 to be Plasmodium mitochondrial DNA (mtDNA) positive, all of which contained human parasites as determined by sequencing and/or restriction enzyme digestion. To exclude low-abundance infections, we subjected 514 of these samples to 454 sequencing, targeting a region of the mtDNA genome that distinguishes ape from human Laverania species. Using algorithms specifically developed to differentiate rare Plasmodium variants from 454-sequencing error, we identified single and mixed-species infections with P. falciparum, Plasmodium malariae, and/or Plasmodium ovale. However, none of the human samples contained ape Laverania parasites, including the gorilla precursor of P. falciparum. To characterize further the diversity of P. falciparum in Cameroon, we used single-genome amplification to amplify 3.4-kb mtDNA fragments from 229 infected humans. Phylogenetic analysis identified 62 new variants, all of which clustered with extant P. falciparum, providing further evidence that P. falciparum emerged following a single gorilla-to-human transmission. Thus, unlike Plasmodium knowlesi-infected macaques in southeast Asia, African apes harboring Laverania parasites do not seem to serve as a recurrent source of human malaria, a finding of import to ongoing control and eradication measures. PMID:23569255

  8. A cross strain Plasmodium falciparum microarray optimized for the transcriptome analysis of Plasmodium falciparum patient derived isolates

    KAUST Repository

    Subudhi, Amit

    2016-07-20

    Malarial parasite P. falciparum, an apicomplexan protozoan has a 23.3 MB nuclear genome and encodes ~ 5600 transcripts. The genetic diversity of the parasite within and across geographical zones is a challenge to gene expression studies which are essential for understanding of disease process, outcome and developing markers for diagnostics and prognostics. Here, we describe the strategy involved in designing a custom P. falciparum 15K array using the Agilent platform and Genotypic\\'s Right Design methodology to study the transcriptome of Indian field isolates for which genome sequence information is limited. The array contains probes representing genome sequences of two distinct geographical isolates (i.e. 3D7 and HB3) and sub-telomeric var gene sequences of a third isolate (IT4) known to adhere in culture condition. Probes in the array have been selected based on their efficiency to detect transcripts through a 244K array experimentation. Array performance for the 15K array, was evaluated and validated using RNA materials from P. falciparum clinical isolates. A large percentage (91%) of the represented transcripts was detected from Indian P. falciparum patient isolates. Replicated probes and multiple probes representing the same gene showed perfect correlation between them suggesting good probe performance. Additional transcripts could be detected due to inclusion of unique probes representing HB3 strain transcripts. Variant surface antigen (VSA) transcripts were detected by optimized probes representing the VSA genes of three geographically distinct strains. The 15K cross strain P. falciparum array has shown good efficiency in detecting transcripts from P. falciparum parasite samples isolated from patients. The low parasite loads and presence of host RNA makes arrays a preferred platform for gene expression studies over RNA-Seq.

  9. Fine-scale genetic characterization of Plasmodium falciparum ...

    Indian Academy of Sciences (India)

    J. Genet. 87, 59–64]. Introduction. Malaria, one of the deadliest, infectious diseases is caused by protozoan parasites of Plasmodium species, affecting about. 300 million individuals around the globe, mainly tropical re- gions of the world causing about one million deaths annually. The parasites have two complex life cycles: ...

  10. Genetic diversity of Plasmodium falciparum field isolates from south ...

    African Journals Online (AJOL)

    Conclusion: The allelic distributions however were similar to those previously reported in other endemic malaria countries. Future studies will be designed to include other malaria endemic regions of Nigeria such as the oil exploration regions. Keywords: Genetic diversity; Plasmodium; Merozoite surface protein, monoclonal ...

  11. Diagnosis of Plasmodium falciparum malaria in children using the ...

    African Journals Online (AJOL)

    Results: The results showed that the diagnosis of falciparum malaria was achieved within eight minutes using the ICT-Malaria P f Ò test kit. The sensitivity of the test kit was 69.6 percent while the specificity was 98.4 percent. However, among patients with severe malaria, the ICT had a sensitivity of 90.3 percent. The test kit ...

  12. Drug Evaluation in the Plasmodium falciparum - Aotus Model

    Science.gov (United States)

    1984-09-01

    falciparum strains in Panamanian and Colombian Aotus indicated that the virulence of these strains, as indicated by lower mortality rates, was less in...monkeys, as shown by lower mortality rates in Panamanian Aotus, although the evolution of parasitemias was more rapid than in the Colombian Aotus model...studies will be summarized as follows: Expt . I. One pump was implanted into each of two Aotus. Parasitemia was suppressed in both hosts. One monkey

  13. Molecular assessment of Plasmodium falciparum resistance to antimalarial drugs in China.

    Science.gov (United States)

    Zhang, G Q; Guan, Y Y; Zheng, B; Wu, S; Tang, L H

    2009-10-01

    In China, Chloroquine (CQ) and sulfadoxine-pyrimethamine (SP) were abandoned for the treatment of falciparum malaria 20 years ago due to resistance. Subsequent field studies showed a trend of declining CQ and SP resistance in the country. The main purpose of this study was to analyse the molecular markers of antimalarial resistance and thereby to assess the possibility of reintroduction of CQ or SP for falciparum malaria treatment. Plasmodium falciparum field isolates were collected in 2006-2007 from Hainan and Yunnan provinces, China. Nested PCR-sequencing assays were applied to analyse the SNPs in four genes: P. falciparum chloroquine resistance transporter (pfcrt) gene, multi-drug resistance 1 (pfmdr1) gene, dihydrofolate reductase (dhfr) gene and dihydropteroate synthetase (dhps) gene. We found the widespread presence of point mutations in the dhfr and dhps genes which are associated with SP treatment failure. The molecular analyses also showed the fairly high prevalence of point mutation in the pfcrt gene which is linked to CQ resistance. The results of the present study indicate that CQ and SP should not be reintroduced for falciparum malaria treatment in the near future in China.

  14. Immunoglobulins against the surface of Plasmodium falciparum-infected erythrocytes increase one month after delivery

    Directory of Open Access Journals (Sweden)

    Mayor Alfredo

    2012-04-01

    Full Text Available Abstract Background The risk of Plasmodium falciparum malaria increases during pregnancy and at early postpartum. Immunological and physiological alterations associated with pregnancy that persist after delivery may contribute to the susceptibility to P. falciparum during early postpartum period. Methods To determine changes in antibody-mediated responses after pregnancy, levels of Immunoglobulin G (IgGs specific for P. falciparum were compared in 200 pairs of plasmas collected from Mozambican women at delivery and during the first two months postpartum. IgGs against the surface of erythrocytes infected with a P. falciparum chondroitin sulphate A binding line (CS2 and a paediatric isolate (MOZ2 were measured by flow cytometry. Results IgG levels against CS2 and MOZ2 were higher at postpartum than at delivery (p = 0.033 and p = 0.045, respectively in women without P. falciparum infection. The analysis stratified by parity and period after delivery showed that this increase was significant in multi-gravid women (p = 0.023 for CS2 and p = 0.054 for MOZ2 and during the second month after delivery (p = 0.018 for CS2 and p = 0.015 for MOZ2. Conclusions These results support the view that early postpartum is a period of recovery from physiological or immunological changes associated with pregnancy.

  15. In vivo transcriptome of Plasmodium falciparum reveals overexpression of transcripts that encode surface proteins.

    Science.gov (United States)

    Daily, Johanna P; Le Roch, Karine G; Sarr, Ousmane; Ndiaye, Daouda; Lukens, Amanda; Zhou, Yingyao; Ndir, Omar; Mboup, Soulyemane; Sultan, Ali; Winzeler, Elizabeth A; Wirth, Dyann F

    2005-04-01

    Infections with the human parasite Plasmodium falciparum continue to present a great challenge to global health. Fundamental questions regarding the molecular basis of virulence and immune evasion in P. falciparum have been only partially answered. Because of the parasite's intracellular location and complex life cycle, standard genetic approaches to the study of the pathogenesis of malaria have been limited. The present study presents a novel approach to the identification of the biological processes involved in host-pathogen interactions, one that is based on the analysis of in vivo P. falciparum transcripts. We demonstrate that a sufficient quantity of P. falciparum RNA transcripts can be derived from a small blood sample from infected patients for whole-genome microarray analysis. Overall, excellent correlation was observed between the transcriptomes derived from in vivo samples and in vitro samples with ring-stage P. falciparum 3D7 reference strain. However, gene families that encode surface proteins are overexpressed in vivo. Moreover, this analysis has identified a new family of hypothetical genes that may encode surface variant antigens. Comparative studies of the transcriptomes derived from in vivo samples and in vitro 3D7 samples may identify important strategies used by the pathogen for survival in the human host and highlight, for vaccine development, new candidate antigens that were not previously identified through the use of in vitro cultures.

  16. The protein-phosphatome of the human malaria parasite Plasmodium falciparum

    Directory of Open Access Journals (Sweden)

    Doerig Christian

    2008-09-01

    Full Text Available Abstract Background Malaria, caused by the parasitic protist Plasmodium falciparum, represents a major public health problem in the developing world. The P. falciparum genome has been sequenced, which provides new opportunities for the identification of novel drug targets. We report an exhaustive analysis of the P. falciparum genomic database (PlasmoDB aimed at identifying and classifying all protein phosphatases (PP in this organism. Results Using a variety of bioinformatics tools, we identified 27 malarial putative PP sequences within the four major established PP families, plus 7 sequences that we predict to dephosphorylate "non-protein" substrates. We constructed phylogenetic trees to position these sequences relative to PPs from other organisms representing all major eukaryotic phyla except Cercozoans (for which no full genome sequence is available. Predominant observations were: (i P. falciparum possessed the smallest phosphatome of any of the organisms investigated in this study; (ii no malarial PP clustered with the tyrosine-specific subfamily of the PTP group (iii a cluster of 7 closely related members of the PPM/PP2C family is present, and (iv some P. falciparum protein phosphatases are present in clades lacking any human homologue. Conclusion The considerable phylogenetic distance between Apicomplexa and other Eukaryotes is reflected by profound divergences between the phosphatome of malaria parasites and those of representative organisms from all major eukaryotic phyla, which might be exploited in the context of efforts for the discovery of novel targets for antimalarial chemotherapy.

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

    Science.gov (United States)

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

    2012-01-01

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

  18. Methylene blue induced morphological deformations in Plasmodium falciparum gametocytes: implications for transmission-blocking.

    Science.gov (United States)

    Wadi, Ishan; Pillai, C Radhakrishna; Anvikar, Anupkumar R; Sinha, Abhinav; Nath, Mahendra; Valecha, Neena

    2018-01-08

    Malaria remains a global health problem despite availability of effective tools. For malaria elimination, drugs targeting sexual stages of Plasmodium falciparum need to be incorporated in treatment regimen along with schizonticidal drugs to interrupt transmission. Primaquine is recommended as a transmission blocking drug for its effect on mature gametocytes but is not extensively utilized because of associated safety concerns among glucose-6-phosphate dehydrogenase (G6PD) deficient patients. In present work, methylene blue, which is proposed as an alternative to primaquine is investigated for its gametocytocidal activity amongst Indian field isolates. An effort has been made to establish Indian field isolates of P. falciparum as in vitro model for gametocytocidal drugs screening. Plasmodium falciparum isolates were adapted to in vitro culture and induced to gametocyte production by hypoxanthine and culture was enriched for gametocyte stages using N-acetyl-glucosamine. Gametocytes were incubated with methylene blue for 48 h and stage specific gametocytocidal activity was evaluated by microscopic examination. Plasmodium falciparum field isolates RKL-9 and JDP-8 were able to reproducibly produce gametocytes in high yield and were used to screen gametocytocidal drugs. Methylene blue was found to target gametocytes in a concentration dependent manner by either completely eliminating gametocytes or rendering them morphologically deformed with mean IC 50 (early stages) as 424.1 nM and mean IC 50 (late stages) as 106.4 nM. These morphologically altered gametocytes appeared highly degenerated having shrinkage, distortions and membrane deformations. Field isolates that produce gametocytes in high yield in vitro can be identified and used to screen gametocytocidal drugs. These isolates should be used for validation of gametocytocidal hits obtained previously by using lab adapted reference strains. Methylene blue was found to target gametocytes produced from Indian field

  19. Genetic polymorphisms in the glutamate-rich protein of Plasmodium falciparum field isolates from a malaria-endemic area of Brazil

    DEFF Research Database (Denmark)

    Pratt-Riccio, Lilian Rose; Perce-da-Silva, Daiana de Souza; Lima-Junior, Josué da Costa

    2013-01-01

    The genetic diversity displayed by Plasmodium falciparum, the most deadly Plasmodium species, is a significant obstacle for effective malaria vaccine development. In this study, we identified genetic polymorphisms in P. falciparum glutamate-rich protein (GLURP), which is currently being tested in...

  20. Mitochondrial genes support a common origin of rodent malaria parasites and Plasmodium falciparum's relatives infecting great apes

    Directory of Open Access Journals (Sweden)

    Blanquart Samuel

    2011-03-01

    Full Text Available Abstract Background Plasmodium falciparum is responsible for the most acute form of human malaria. Most recent studies demonstrate that it belongs to a monophyletic lineage specialized in the infection of great ape hosts. Several other Plasmodium species cause human malaria. They all belong to another distinct lineage of parasites which infect a wider range of primate species. All known mammalian malaria parasites appear to be monophyletic. Their clade includes the two previous distinct lineages of parasites of primates and great apes, one lineage of rodent parasites, and presumably Hepatocystis species. Plasmodium falciparum and great ape parasites are commonly thought to be the sister-group of all other mammal-infecting malaria parasites. However, some studies supported contradictory origins and found parasites of great apes to be closer to those of rodents, or to those of other primates. Results To distinguish between these mutually exclusive hypotheses on the origin of Plasmodium falciparum and its great ape infecting relatives, we performed a comprehensive phylogenetic analysis based on a data set of three mitochondrial genes from 33 to 84 malaria parasites. We showed that malarial mitochondrial genes have evolved slowly and are compositionally homogeneous. We estimated their phylogenetic relationships using Bayesian and maximum-likelihood methods. Inferred trees were checked for their robustness to the (i site selection, (ii assumptions of various probabilistic models, and (iii taxon sampling. Our results robustly support a common ancestry of rodent parasites and Plasmodium falciparum's relatives infecting great apes. Conclusions Our results refute the most common view of the origin of great ape malaria parasites, and instead demonstrate the robustness of a less well-established phylogenetic hypothesis, under which Plasmodium falciparum and its relatives infecting great apes are closely related to rodent parasites. This study sheds light

  1. Mitochondrial genes support a common origin of rodent malaria parasites and Plasmodium falciparum's relatives infecting great apes.

    Science.gov (United States)

    Blanquart, Samuel; Gascuel, Olivier

    2011-03-15

    Plasmodium falciparum is responsible for the most acute form of human malaria. Most recent studies demonstrate that it belongs to a monophyletic lineage specialized in the infection of great ape hosts. Several other Plasmodium species cause human malaria. They all belong to another distinct lineage of parasites which infect a wider range of primate species. All known mammalian malaria parasites appear to be monophyletic. Their clade includes the two previous distinct lineages of parasites of primates and great apes, one lineage of rodent parasites, and presumably Hepatocystis species. Plasmodium falciparum and great ape parasites are commonly thought to be the sister-group of all other mammal-infecting malaria parasites. However, some studies supported contradictory origins and found parasites of great apes to be closer to those of rodents, or to those of other primates. To distinguish between these mutually exclusive hypotheses on the origin of Plasmodium falciparum and its great ape infecting relatives, we performed a comprehensive phylogenetic analysis based on a data set of three mitochondrial genes from 33 to 84 malaria parasites. We showed that malarial mitochondrial genes have evolved slowly and are compositionally homogeneous. We estimated their phylogenetic relationships using Bayesian and maximum-likelihood methods. Inferred trees were checked for their robustness to the (i) site selection, (ii) assumptions of various probabilistic models, and (iii) taxon sampling. Our results robustly support a common ancestry of rodent parasites and Plasmodium falciparum's relatives infecting great apes. Our results refute the most common view of the origin of great ape malaria parasites, and instead demonstrate the robustness of a less well-established phylogenetic hypothesis, under which Plasmodium falciparum and its relatives infecting great apes are closely related to rodent parasites. This study sheds light on the evolutionary history of Plasmodium falciparum, a

  2. Sero-epidemiological evaluation of changes in Plasmodium falciparum and Plasmodium vivax transmission patterns over the rainy season in Cambodia

    Directory of Open Access Journals (Sweden)

    Cook Jackie

    2012-03-01

    Full Text Available Abstract Background In Cambodia, malaria transmission is low and most cases occur in forested areas. Sero-epidemiological techniques can be used to identify both areas of ongoing transmission and high-risk groups to be targeted by control interventions. This study utilizes repeated cross-sectional data to assess the risk of being malaria sero-positive at two consecutive time points during the rainy season and investigates who is most likely to sero-convert over the transmission season. Methods In 2005, two cross-sectional surveys, one in the middle and the other at the end of the malaria transmission season, were carried out in two ecologically distinct regions in Cambodia. Parasitological and serological data were collected in four districts. Antibodies to Plasmodium falciparum Glutamate Rich Protein (GLURP and Plasmodium vivax Merozoite Surface Protein-119 (MSP-119 were detected using Enzyme Linked Immunosorbent Assay (ELISA. The force of infection was estimated using a simple catalytic model fitted using maximum likelihood methods. Risks for sero-converting during the rainy season were analysed using the Classification and Regression Tree (CART method. Results A total of 804 individuals participating in both surveys were analysed. The overall parasite prevalence was low (4.6% and 2.0% for P. falciparum and 7.9% and 6.0% for P. vivax in August and November respectively. P. falciparum force of infection was higher in the eastern region and increased between August and November, whilst P. vivax force of infection was higher in the western region and remained similar in both surveys. In the western region, malaria transmission changed very little across the season (for both species. CART analysis for P. falciparum in the east highlighted age, ethnicity, village of residence and forest work as important predictors for malaria exposure during the rainy season. Adults were more likely to increase their antibody responses to P. falciparum during the

  3. The humoral response to Plasmodium falciparum VarO rosetting variant and its association with protection against malaria in Beninese children

    Directory of Open Access Journals (Sweden)

    Bentley Graham

    2010-10-01

    Full Text Available Abstract Background The capacity of Plasmodium falciparum-infected erythrocytes to bind uninfected erythrocytes (rosetting is associated with severe malaria in African children. Rosetting is mediated by a subset of the variant surface antigens PfEMP1 targeted by protective antibody responses. Analysis of the response to rosette-forming parasites and their PfEMP1 adhesive domains is essential for understanding the acquisition of protection against severe malaria. To this end, the antibody response to a rosetting variant was analysed in children recruited with severe or uncomplicated malaria or asymptomatic P. falciparum infection. Methods Serum was collected from Beninese children with severe malaria, uncomplicated malaria or P. falciparum asymptomatic infection (N = 65, 37 and 52, respectively and from immune adults (N = 30 living in the area. Infected erythrocyte surface-reactive IgG, rosette disrupting antibodies and IgG to the parasite crude extract were analysed using the single variant Palo Alto VarO-infected line. IgG, IgG1 and IgG3 to PfEMP1-varO-derived NTS-DBL1α1, CIDRγ and DBL2βC2 recombinant domains were analysed by ELISA. Antibody responses were compared in the clinical groups. Stability of the response was studied using a blood sampling collected 14 months later from asymptomatic children. Results Seroprevalence of erythrocyte surface-reactive IgG was high in adults (100% and asymptomatic children (92.3% but low in children with severe or uncomplicated malaria (26.1% and 37.8%, respectively. The IgG, IgG1 and IgG3 antibody responses to the varO-derived PfEMP1 domains were significantly higher in asymptomatic children than in children with clinical malaria in a multivariate analysis correcting for age and parasite density at enrolment. They were essentially stable, although levels tended to decrease with time. VarO-surface reactivity correlated positively with IgG reactivity to the rosetting domain varO-NTS-DBL1α1. None of the

  4. Plasmodium falciparum centromeres display a unique epigenetic makeup and cluster prior to and during schizogony.

    Science.gov (United States)

    Hoeijmakers, Wieteke A M; Flueck, Christian; Françoijs, Kees-Jan; Smits, Arne H; Wetzel, Johanna; Volz, Jennifer C; Cowman, Alan F; Voss, Till; Stunnenberg, Hendrik G; Bártfai, Richárd

    2012-09-01

    Centromeres are essential for the faithful transmission of chromosomes to the next generation, therefore being essential in all eukaryotic organisms. The centromeres of Plasmodium falciparum, the causative agent of the most severe form of malaria, have been broadly mapped on most chromosomes, but their epigenetic composition remained undefined. Here, we reveal that the centromeric histone variant PfCENH3 occupies a 4-4.5 kb region on each P. falciparum chromosome, which is devoid of pericentric heterochromatin but harbours another histone variant, PfH2A.Z. These CENH3 covered regions pinpoint the exact position of the centromere on all chromosomes and revealed that all centromeric regions have similar size and sequence composition. Immunofluorescence assay of PfCENH3 strongly suggests that P. falciparum centromeres cluster to a single nuclear location prior to and during mitosis and cytokinesis but dissociate soon after invasion. In summary, we reveal a dynamic association of Plasmodium centromeres, which bear a unique epigenetic signature and conform to a strict structure. These findings suggest that DNA-associated and epigenetic elements play an important role in centromere establishment in this important human pathogen. © 2012 Blackwell Publishing Ltd.

  5. The antimalarial drug, chloroquine, interacts with lactate dehydrogenase from Plasmodium falciparum.

    Science.gov (United States)

    Menting, J G; Tilley, L; Deady, L W; Ng, K; Simpson, R J; Cowman, A F; Foley, M

    1997-09-01

    We have previously shown that a radioiodinated photoreactive analogue of chloroquine, [125I]N-(4-(4-diethylamino-1-methylbutylamino)quinolin-6-yl) -4-azido-2-hydroxybenzamide ([125I]ASA-Q), specifically labels two proteins in Plasmodium falciparum with apparent molecular weights (Mr) of 42 and 33 kDa (Foley M, Deady LW, Ng K, Cowman AF, Tilley L. J Biol Chem 1994:269:6955-6961). We now report the identification of the 33 kDa protein. The 33 kDa protein was purified from Plasmodium falciparum using photoaffinity labeling with [125I]ASA-Q to monitor the enrichment process. N-terminal sequence analysis of the purified protein revealed exact identity of the first 35 amino acids with P. falciparum lactate dehydrogenase (PfLDH). The plasmodial enzyme was cloned and expressed in E. coli and the recombinant protein used to produce a rabbit antiserum. Immunoprecipitation using affinity-purified anti-PfLDH antibodies confirmed the identity of the 33 kDa CQ-binding protein. The enzyme activity of purified PfLDH was not significantly affected by chloroquine indicating that PfLDH is not a direct target of CQ. PfLDH was, however, shown to be exquisitely sensitive to inhibition by free heme and chloroquine protected against this inhibitory effect.

  6. Plasmodium falciparum-Derived Uric Acid Precipitates Induce Maturation of Dendritic Cells

    Science.gov (United States)

    van de Hoef, Diana L.; Coppens, Isabelle; Holowka, Thomas; Ben Mamoun, Choukri; Branch, OraLee; Rodriguez, Ana

    2013-01-01

    Malaria is characterized by cyclical fevers and high levels of inflammation, and while an early inflammatory response contributes to parasite clearance, excessive and persistent inflammation can lead to severe forms of the disease. Here, we show that Plasmodium falciparum-infected erythrocytes contain uric acid precipitates in the cytoplasm of the parasitophorous vacuole, which are released when erythrocytes rupture. Uric acid precipitates are highly inflammatory molecules that are considered a danger signal for innate immunity and are the causative agent in gout. We determined that P. falciparum-derived uric acid precipitates induce maturation of human dendritic cells, increasing the expression of cell surface co-stimulatory molecules such as CD80 and CD86, while decreasing human leukocyte antigen-DR expression. In accordance with this, uric acid accounts for a significant proportion of the total stimulatory activity induced by parasite-infected erythrocytes. Moreover, the identification of uric acid precipitates in P. falciparum- and P. vivax-infected erythrocytes obtained directly from malaria patients underscores the in vivo and clinical relevance of our findings. Altogether, our data implicate uric acid precipitates as a potentially important contributor to the innate immune response to Plasmodium infection and may provide a novel target for adjunct therapies. PMID:23405174

  7. An FtsH protease is recruited to the mitochondrion of Plasmodium falciparum.

    Directory of Open Access Journals (Sweden)

    Aiman Tanveer

    Full Text Available The two organelles, apicoplast and mitochondrion, of the malaria parasite Plasmodium falciparum have unique morphology in liver and blood stages; they undergo complex branching and looping prior to division and segregation into daughter merozoites. Little is known about the molecular processes and proteins involved in organelle biogenesis in the parasite. We report the identification of an AAA+/FtsH protease homolog (PfFtsH1 that exhibits ATP- and Zn(2+-dependent protease activity. PfFtsH1 undergoes processing, forms oligomeric assemblies, and is associated with the membrane fraction of the parasite cell. Generation of a transfectant parasite line with hemagglutinin-tagged PfFtsH1, and immunofluorescence assay with anti-PfFtsH1 Ab demonstrated that the protein localises to P. falciparum mitochondria. Phylogenetic analysis and the single transmembrane region identifiable in PfFtsH1 suggest that it is an i-AAA like inner mitochondrial membrane protein. Expression of PfFtsH1 in Escherichia coli converted a fraction of bacterial cells into division-defective filamentous forms implying a sequestering effect of the Plasmodium factor on the bacterial homolog, indicative of functional conservation with EcFtsH. These results identify a membrane-associated mitochondrial AAA+/FtsH protease as a candidate regulatory protein for organelle biogenesis in P. falciparum.

  8. Characterisation of the Plasmodium falciparum Hsp70-Hsp90 organising protein (PfHop).

    Science.gov (United States)

    Gitau, Grace W; Mandal, Pradipta; Blatch, Gregory L; Przyborski, Jude; Shonhai, Addmore

    2012-03-01

    Malaria is caused by Plasmodium species, whose transmission to vertebrate hosts is facilitated by mosquito vectors. The transition from the cold blooded mosquito vector to the host represents physiological stress to the parasite, and additionally malaria blood stage infection is characterised by intense fever periods. In recent years, it has become clear that heat shock proteins play an essential role during the parasite's life cycle. Plasmodium falciparum expresses two prominent heat shock proteins: heat shock protein 70 (PfHsp70) and heat shock protein 90 (PfHsp90). Both of these proteins have been implicated in the development and pathogenesis of malaria. In eukaryotes, Hsp70 and Hsp90 proteins are functionally linked by an essential adaptor protein known as the Hsp70-Hsp90 organising protein (Hop). In this study, recombinant P. falciparum Hop (PfHop) was heterologously produced in E. coli and purified by nickel affinity chromatography. Using specific anti-PfHop antisera, the expression and localisation of PfHop in P. falciparum was investigated. PfHop was shown to co-localise with PfHsp70 and PfHsp90 in parasites at the trophozoite stage. Gel filtration and co-immunoprecipitation experiments suggested that PfHop was present in a complex together with PfHsp70 and PfHsp90. The association of PfHop with both PfHsp70 and PfHsp90 suggests that this protein may mediate the functional interaction between the two chaperones.

  9. Plasmodium falciparum Adhesins Play an Essential Role in Signalling and Activation of Invasion into Human Erythrocytes.

    Directory of Open Access Journals (Sweden)

    Wai-Hong Tham

    2015-12-01

    Full Text Available The most severe form of malaria in humans is caused by the protozoan parasite Plasmodium falciparum. The invasive form of malaria parasites is termed a merozoite and it employs an array of parasite proteins that bind to the host cell to mediate invasion. In Plasmodium falciparum, the erythrocyte binding-like (EBL and reticulocyte binding-like (Rh protein families are responsible for binding to specific erythrocyte receptors for invasion and mediating signalling events that initiate active entry of the malaria parasite. Here we have addressed the role of the cytoplasmic tails of these proteins in activating merozoite invasion after receptor engagement. We show that the cytoplasmic domains of these type 1 membrane proteins are phosphorylated in vitro. Depletion of PfCK2, a kinase implicated to phosphorylate these cytoplasmic tails, blocks P. falciparum invasion of red blood cells. We identify the crucial residues within the PfRh4 cytoplasmic domain that are required for successful parasite invasion. Live cell imaging of merozoites from these transgenic mutants show they attach but do not penetrate erythrocytes implying the PfRh4 cytoplasmic tail conveys signals important for the successful completion of the invasion process.

  10. Falciparum malaria in the north of Laos: the occurrence and implications of the Plasmodium falciparum chloroquine resistance transporter (pfcrt) gene haplotype SVMNT

    DEFF Research Database (Denmark)

    Dittrich, Sabine; Alifrangis, Michael; Stohrer, Jörg M

    2005-01-01

    OBJECTIVE: The Pfcrt-gene encodes a transmembrane protein located in the Plasmodium falciparum digestive vacuole. Chloroquine resistant (CQR) strains of African and Southeast Asian origin carry the Pfcrt-haplotype (c72-76) CVIET, whereas most South American and Papua New Guinean CQR stains carry ......% prevalence of a potential resistance marker is cause for concern....

  11. Malarial parasite diversity in chimpanzees: the value of comparative approaches to ascertain the evolution of Plasmodium falciparum antigens

    Science.gov (United States)

    2013-01-01

    Background Plasmodium falciparum shares its most recent common ancestor with parasites found in African apes; these species constitute the so-called Laverania clade. In this investigation, the evolutionary history of Plasmodium lineages found in chimpanzees (Pan troglodytes) was explored. Methods Here, the remainders of 74 blood samples collected as part of the chimpanzees’ routine health examinations were studied. For all positive samples with parasite lineages belonging to the Laverania clade, the complete mitochondrial genome (mtDNA), the gene encoding dihydrofolate reductase-thymidylate synthase (dhfr-ts), the chloroquine resistance transporter (Pfcrt), the circumsporozoite protein (csp), merozoite surface protein 2 (msp2), and the DBL-1 domain from var2CSA were amplified, cloned, and sequenced. Other Plasmodium species were included in the mtDNA, dhfr-ts, and csp analyses. Phylogenetic and evolutionary genetic analyses were performed, including molecular clock analyses on the mtDNA. Results/Conclusions Nine chimpanzees were malaria positive (12.2%); four of those infections were identified as P. falciparum, two as a Plasmodium reichenowi-like parasite or Plasmodium sp., one as Plasmodium gaboni, and two as Plasmodium malariae. All P. falciparum isolates were resistant to chloroquine indicating that the chimpanzees acquired such infections from humans in recent times. Such findings, however, are not sufficient for implicating chimpanzees as an animal reservoir for P. falciparum. Timing estimates support that the Laverania clade has co-existed with hominids for a long-period of time. The proposed species P. gaboni, Plasmodium billbrayi, and Plasmodium billcollinsi are monophyletic groups supporting that they are indeed different species. An expanded CSP phylogeny is presented, including all the Laverania species and other malarial parasites. Contrasting with other Plasmodium, the Laverania csp exhibits great conservation at the central tandem repeat region

  12. DNA Repair Mechanisms and Their Biological Roles in the Malaria Parasite Plasmodium falciparum

    Science.gov (United States)

    Lee, Andrew H.; Symington, Lorraine S.

    2014-01-01

    SUMMARY Research into the complex genetic underpinnings of the malaria parasite Plasmodium falciparum is entering a new era with the arrival of site-specific genome engineering. Previously restricted only to model systems but now expanded to most laboratory organisms, and even to humans for experimental gene therapy studies, this technology allows researchers to rapidly generate previously unattainable genetic modifications. This technological advance is dependent on DNA double-strand break repair (DSBR), specifically homologous recombination in the case of Plasmodium. Our understanding of DSBR in malaria parasites, however, is based largely on assumptions and knowledge taken from other model systems, which do not always hold true in Plasmodium. Here we describe the causes of double-strand breaks, the mechanisms of DSBR, and the differences between model systems and P. falciparum. These mechanisms drive basic parasite functions, such as meiosis, antigen diversification, and copy number variation, and allow the parasite to continually evolve in the contexts of host immune pressure and drug selection. Finally, we discuss the new technologies that leverage DSBR mechanisms to accelerate genetic investigations into this global infectious pathogen. PMID:25184562

  13. Temporal association of acute hepatitis A and Plasmodium falciparum malaria in children.

    Directory of Open Access Journals (Sweden)

    Peter Klein Klouwenberg

    Full Text Available BACKGROUND: In sub-Saharan Africa, Plasmodium falciparum and hepatitis A (HAV infections are common, especially in children. Co-infections with these two pathogens may therefore occur, but it is unknown if temporal clustering exists. MATERIALS AND METHODS: We studied the pattern of co-infection of P. falciparum malaria and acute HAV in Kenyan children under the age of 5 years in a cohort of children presenting with uncomplicated P. falciparum malaria. HAV status was determined during a 3-month follow-up period. DISCUSSION: Among 222 cases of uncomplicated malaria, 10 patients were anti-HAV IgM positive. The incidence of HAV infections during P. falciparum malaria was 1.7 (95% CI 0.81-3.1 infections/person-year while the cumulative incidence of HAV over the 3-month follow-up period was 0.27 (95% CI 0.14-0.50 infections/person-year. Children with or without HAV co-infections had similar mean P. falciparum asexual parasite densities at presentation (31,000/µL vs. 34,000/µL, respectively, largely exceeding the pyrogenic threshold of 2,500 parasites/µL in this population and minimizing risk of over-diagnosis of malaria as an explanation. CONCLUSION: The observed temporal association between acute HAV and P. falciparum malaria suggests that co-infections of these two hepatotrophic human pathogens may result from changes in host susceptibility. Testing this hypothesis will require larger prospective studies.

  14. Genetic diversity of the merozoite surface protein-3 gene in Plasmodium falciparum populations in Thailand

    Directory of Open Access Journals (Sweden)

    Sittiporn Pattaradilokrat

    2016-10-01

    Full Text Available Abstract Background An effective malaria vaccine is an urgently needed tool to fight against human malaria, the most deadly parasitic disease of humans. One promising candidate is the merozoite surface protein-3 (MSP-3 of Plasmodium falciparum. This antigenic protein, encoded by the merozoite surface protein (msp-3 gene, is polymorphic and classified according to size into the two allelic types of K1 and 3D7. A recent study revealed that both the K1 and 3D7 alleles co-circulated within P. falciparum populations in Thailand, but the extent of the sequence diversity and variation within each allelic type remains largely unknown. Methods The msp-3 gene was sequenced from 59 P. falciparum samples collected from five endemic areas (Mae Hong Son, Kanchanaburi, Ranong, Trat and Ubon Ratchathani in Thailand and analysed for nucleotide sequence diversity, haplotype diversity and deduced amino acid sequence diversity. The gene was also subject to population genetic analysis (F st and neutrality tests (Tajima’s D, Fu and Li D* and Fu and Li’ F* tests to determine any signature of selection. Results The sequence analyses revealed eight unique DNA haplotypes and seven amino acid sequence variants, with a haplotype and nucleotide diversity of 0.828 and 0.049, respectively. Neutrality tests indicated that the polymorphism detected in the alanine heptad repeat region of MSP-3 was maintained by positive diversifying selection, suggesting its role as a potential target of protective immune responses and supporting its role as a vaccine candidate. Comparison of MSP-3 variants among parasite populations in Thailand, India and Nigeria also inferred a close genetic relationship between P. falciparum populations in Asia. Conclusion This study revealed the extent of the msp-3 gene diversity in P. falciparum in Thailand, providing the fundamental basis for the better design of future blood stage malaria vaccines against P. falciparum.

  15. Assessing functional annotation transfers with inter-species conserved coexpression: application to Plasmodium falciparum

    Directory of Open Access Journals (Sweden)

    Maréchal Éric

    2010-01-01

    Full Text Available Abstract Background Plasmodium falciparum is the main causative agent of malaria. Of the 5 484 predicted genes of P. falciparum, about 57% do not have sufficient sequence similarity to characterized genes in other species to warrant functional assignments. Non-homology methods are thus needed to obtain functional clues for these uncharacterized genes. Gene expression data have been widely used in the recent years to help functional annotation in an intra-species way via the so-called Guilt By Association (GBA principle. Results We propose a new method that uses gene expression data to assess inter-species annotation transfers. Our approach starts from a set of likely orthologs between a reference species (here S. cerevisiae and D. melanogaster and a query species (P. falciparum. It aims at identifying clusters of coexpressed genes in the query species whose coexpression has been conserved in the reference species. These conserved clusters of coexpressed genes are then used to assess annotation transfers between genes with low sequence similarity, enabling reliable transfers of annotations from the reference to the query species. The approach was used with transcriptomic data sets of P. falciparum, S. cerevisiae and D. melanogaster, and enabled us to propose with high confidence new/refined annotations for several dozens hypothetical/putative P. falciparum genes. Notably, we revised the annotation of genes involved in ribosomal proteins and ribosome biogenesis and assembly, thus highlighting several potential drug targets. Conclusions Our approach uses both sequence similarity and gene expression data to help inter-species gene annotation transfers. Experiments show that this strategy improves the accuracy achieved when using solely sequence similarity and outperforms the accuracy of the GBA approach. In addition, our experiments with P. falciparum show that it can infer a function for numerous hypothetical genes.

  16. Whole genome sequencing of Plasmodium falciparum from dried blood spots using selective whole genome amplification.

    Science.gov (United States)

    Oyola, Samuel O; Ariani, Cristina V; Hamilton, William L; Kekre, Mihir; Amenga-Etego, Lucas N; Ghansah, Anita; Rutledge, Gavin G; Redmond, Seth; Manske, Magnus; Jyothi, Dushyanth; Jacob, Chris G; Otto, Thomas D; Rockett, Kirk; Newbold, Chris I; Berriman, Matthew; Kwiatkowski, Dominic P

    2016-12-20

    Translating genomic technologies into healthcare applications for the malaria parasite Plasmodium falciparum has been limited by the technical and logistical difficulties of obtaining high quality clinical samples from the field. Sampling by dried blood spot (DBS) finger-pricks can be performed safely and efficiently with minimal resource and storage requirements compared with venous blood (VB). Here, the use of selective whole genome amplification (sWGA) to sequence the P. falciparum genome from clinical DBS samples was evaluated, and the results compared with current methods that use leucodepleted VB. Parasite DNA with high (>95%) human DNA contamination was selectively amplified by Phi29 polymerase using short oligonucleotide probes of 8-12 mers as primers. These primers were selected on the basis of their differential frequency of binding the desired (P. falciparum DNA) and contaminating (human) genomes. Using sWGA method, clinical samples from 156 malaria patients, including 120 paired samples for head-to-head comparison of DBS and leucodepleted VB were sequenced. Greater than 18-fold enrichment of P. falciparum DNA was achieved from DBS extracts. The parasitaemia threshold to achieve >5× coverage for 50% of the genome was 0.03% (40 parasites per 200 white blood cells). Over 99% SNP concordance between VB and DBS samples was achieved after excluding missing calls. The sWGA methods described here provide a reliable and scalable way of generating P. falciparum genome sequence data from DBS samples. The current data indicate that it will be possible to get good quality sequence on most if not all drug resistance loci from the majority of symptomatic malaria patients. This technique overcomes a major limiting factor in P. falciparum genome sequencing from field samples, and paves the way for large-scale epidemiological applications.

  17. Antibodies to a recombinant glutamate-rich Plasmodium falciparum protein

    DEFF Research Database (Denmark)

    Hogh, B; Petersen, E; Dziegiel, M

    1992-01-01

    areas of repeated amino acid sequences. Antibodies against recombinant GLURP489-1271, as well as against a synthetic peptide corresponding to GLURP899-916, and against a synthetic peptide representing the major glutamate rich repeat sequence from the P. falciparum ring erythrocyte surface antigen (Pf155....../RESA) (EENV)6 were examined in 423 individuals (age range 30 days-78 years) living in a malaria holoendemic area of Liberia. In the 5-9-year-old age group, subjects with anti-GLURP489-1271 antibody concentrations greater than the mean value of the group had lower parasite densities than those with low...... antibody concentrations (P = 0.0151). High levels of anti-GLURP899-916 antibodies did not correlate with low parasite densities. However, high levels of anti-(EENV)6 antibodies were associated with significantly lower parasite densities in the 2-4-year-old age group (P = 0.0189). There was no correlation...

  18. [Pharmacokinetics of amodiaquine and prevention of Plasmodium falciparum malaria].

    Science.gov (United States)

    Pussard, E; Verdier, F; Faurisson, F; Blayo, M C

    1985-01-01

    Amodiaquine might appear as an alternative in prophylaxis of chloroquine-resistant P. falciparum malaria. In an attempt to explain the discrepancy between its in vivo-in vitro activity, a pharmacokinetic study was conducted in healthy subjects with HPLC assays. The results showed that: amodiaquine was no more detected in the blood, a main metabolite (monodesethyl derivative) appeared as the active form of the drug in vivo, metabolite's half-life had a mean value of 15.6 +/- 5.4 days. This study shows that monodesethylamodiaquine (and not amodiaquine) must be monitored in vitro. Furthermore the high individual variations of blood levels and half-life's values suggest that the weekly prophylactic schedule must be eventually re-evaluated.

  19. Adverse pregnancy outcomes in an area where multidrug-resistant plasmodium vivax and Plasmodium falciparum infections are endemic.

    Science.gov (United States)

    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

    2008-05-01

    Plasmodium falciparum infection exerts a considerable burden on pregnant women, but less is known about the adverse consequences of Plasmodium vivax infection. 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. 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. 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.

  20. Improved assay to detect Plasmodium falciparum using an uninterrupted, semi-nested PCR and quantitative lateral flow analysis

    OpenAIRE

    Ongagna-Yhombi, Serge Y; Corstjens, Paul; Geva, Eran; Abrams, William R.; Barber, Cheryl A.; Malamud, Daniel; Mharakurwa, Sungano

    2013-01-01

    Background A rapid, non-invasive, and inexpensive point-of-care (POC) diagnostic for malaria followed by therapeutic intervention would improve the ability to control infection in endemic areas. Methods A semi-nested PCR amplification protocol is described for quantitative detection of Plasmodium falciparum and is compared to a traditional nested PCR. The approach uses primers that target the P. falciparum dihydrofolate reductase gene. Results This study demonstrates that it is possible to pe...

  1. Infectivity of Plasmodium falciparum in Malaria-Naive Individuals Is Related to Knob Expression and Cytoadherence of the Parasite

    OpenAIRE

    Danielle I Stanisic; Gerrard, John; Fink, James; Griffin, Paul M.; Liu, Xue Q; Sundac, Lana; Sekuloski, Silvana; Rodriguez, Ingrid B.; Pingnet, Jolien; Yang, Yuedong; Zhou, Yaoqi; TRENHOLME, KATHARINE R.; Wang, Claire Y. T.; Hackett, Hazel; Chan, Jo-Anne A.

    2016-01-01

    Plasmodium falciparum is the most virulent human malaria parasite because of its ability to cytoadhere in the microvasculature. Nonhuman primate studies demonstrated relationships among knob expression, cytoadherence, and infectivity. This has not been examined in humans. Cultured clinical-grade P. falciparum parasites (NF54, 7G8, and 3D7B) and ex vivo-derived cell banks were characterized. Knob and knob-associated histidine-rich protein expression, CD36 adhesion, and antibody recognition of ...

  2. Genome-wide discovery and verification of novel structured RNAs in Plasmodium falciparum

    DEFF Research Database (Denmark)

    Mourier, Tobias; Carret, Celine; Kyes, Sue

    2008-01-01

    We undertook a genome-wide search for novel noncoding RNAs (ncRNA) in the malaria parasite Plasmodium falciparum. We used the RNAz program to predict structures in the noncoding regions of the P. falciparum 3D7 genome that were conserved with at least one of seven other Plasmodium spp. genome...... chimp malaria parasite P. reichenowi. The high confirmation rate within a single parasite life cycle stage suggests that many more of the predictions may be expressed in other stages of the organism's life cycle....

  3. Gibberellin biosynthetic inhibitors make human malaria parasite Plasmodium falciparum cells swell and rupture to death.

    Directory of Open Access Journals (Sweden)

    Tomoko Toyama

    Full Text Available Malaria remains as one of the most devastating infectious disease, and continues to exact an enormous toll in medical cost and days of labor lost especially in the tropics. Effective malaria control and eventual eradication remain a huge challenge, with efficacious antimalarials as important intervention/management tool. Clearly new alternative drugs that are more affordable and with fewer side effects are desirable. After preliminary in vitro assays with plant growth regulators and inhibitors, here, we focus on biosynthetic inhibitors of gibberellin, a plant hormone with many important roles in plant growth, and show their inhibitory effect on the growth of both apicomplexa, Plasmodium falciparum and Toxoplasma gondii. Treatment of P. falciparum cultures with the gibberellin biosynthetic inhibitors resulted in marked morphological changes that can be reversed to a certain degree under hyperosmotic environment. These unique observations suggest that changes in the parasite membrane permeability may explain the pleiotropic effects observed within the intracellular parasites.

  4. Plasmodium falciparum sulfadoxine resistance is geographically and genetically clustered within the DR Congo

    Science.gov (United States)

    Taylor, Steve M.; Antonia, Alejandro L.; Parobek, Christian M.; Juliano, Jonathan J.; Janko, Mark; Emch, Michael; Alam, Md Tauqeer; Udhayakumar, Venkatachalam; Tshefu, Antoinette K.; Meshnick, Steven R.

    2013-01-01

    Understanding the spatial clustering of Plasmodium falciparum populations can assist efforts to contain drug-resistant parasites and maintain the efficacy of future drugs. We sequenced single nucleotide polymorphisms (SNPs) in the dihydropteroate synthase gene (dhps) associated with sulfadoxine resistance and 5 microsatellite loci flanking dhps in order to investigate the genetic backgrounds, genetic relatedness, and geographic clustering of falciparum parasites in the Democratic Republic of the Congo (DRC). Resistant haplotypes were clustered into subpopulations: one in the northeast DRC, and the other in the balance of the DRC. Network and clonal lineage analyses of the flanking microsatellites indicate that geographically-distinct mutant dhps haplotypes derive from separate lineages. The DRC is therefore a watershed for haplotypes associated with sulfadoxine resistance. Given the importance of central Africa as a corridor for the spread of antimalarial resistance, the identification of the mechanisms of this transit can inform future policies to contain drug-resistant parasite strains. PMID:23372922

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

    Science.gov (United States)

    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

  6. Activity of benflumetol and its enantiomers in fresh isolates of Plasmodium falciparum from East Africa.

    Science.gov (United States)

    Wernsdorfer, W H; Landgraf, B; Kilimali, V A; Wernsdorfer, G

    1998-06-15

    Benflumetol, a novel antimalarial compound belonging to the fluorenes (2,3-benzindenes), has high blood schizontocidal activity, in vitro and in vivo, against mammalian plasmodia, including chloroquine-resistant Plasmodium falciparum. Due to its molecular structure benflumetol occurs in the dextrorotatory and the laevorotatory form. Normal synthesis yields the racemate of both enantiomers. Enantiomers of some antimalarial drugs possess different specific activity. It was therefore of interest to compare the response of P. falciparum to the enantiomers and the racemate of benflumetol in a variety of fresh, natural isolates. Measuring the concentration-specific inhibition of schizont maturation, the parallel investigation of 29 isolates produced no evidence of substantial activity differences between (+)-benflumetol, (-)-benflumetol and racemic benflumetol, the mean EC-50 values being 8.87, 9.71 and 12.44 nmol/l blood-medium-mixture, respectively.

  7. Expression and immunogenicity of the Plasmodium falciparum circumsporozoite protein: the role of GPI signal sequence.

    Science.gov (United States)

    Ophorst, Olga J A E; Radosević, Katarina; Ouwehand, Krista; van Beem, Wouter; Mintardjo, Ratna; Sijtsma, Jeroen; Kaspers, Jorn; Companjen, Arjen; Holterman, Lennart; Goudsmit, Jaap; Havenga, Menzo J E

    2007-02-09

    Previous studies have shown that the immunogenicity of rodent malaria parasite-derived circumsporozoite protein (CS) can be improved by deleting the glycosyl-phosphatidyl-inositol (GPI) signal sequence. To study whether GPI signal sequence deletion would also improve immunogenicity of CS derived from the major plasmodium species causing mortality in humans (P. falciparum), we tested different variants of the P. falciparum CS protein in the context of a live vector-based vaccine carrier (rAd35). We demonstrate that deletion of the GPI signal sequence from CS did not result in altered expression or secretion. In contrast, cellular localization was clearly altered, which perhaps helps to explain the significant improvement of anti-CS antibody and T-cell responses observed in mice using deletion variants in the context of the rAd35 carrier. Our results show that rational design of antigens is warranted for further development of malaria vaccines.

  8. A fresh look at the origin of Plasmodium falciparum, the most malignant malaria agent.

    Directory of Open Access Journals (Sweden)

    Franck Prugnolle

    2011-02-01

    Full Text Available From which host did the most malignant human malaria come: birds, primates, or rodents? When did the transfer occur? Over the last half century, these have been some of the questions up for debate about the origin of Plasmodium falciparum, the most common and deadliest human malaria parasite, which is responsible for at least one million deaths every year. Recent findings bring elements in favor of a transfer from great apes, but are these evidences really solid? What are the grey areas that remain to be clarified? Here, we examine in depth these new elements and discuss how they modify our perception of the origin and evolution of P. falciparum. We also discuss the perspectives these new discoveries open.

  9. The mechanism of erythrocyte invasion by the malarial parasite, Plasmodium falciparum.

    Science.gov (United States)

    Farrow, Rachel E; Green, Judith; Katsimitsoulia, Zoe; Taylor, William R; Holder, Anthony A; Molloy, Justin E

    2011-12-01

    Plasmodium falciparum is the most virulent causative agent of malaria in man accounting for 80% of all malarial infections and 90% of the one million annual deaths attributed to malaria. P. falciparum is a unicellular, Apicomplexan parasite, that spends part of its lifecycle in the mosquito and part in man and it has evolved a special form of motility that enables it to burrow into animal cells, a process termed "host cell invasion". The acute, life threatening, phase of malarial infection arises when the merozoite form of the parasite undergoes multiple cycles of red blood cell invasion and rapid proliferation. Here, we discuss the molecular machinery that enables malarial parasites to invade red blood cells and we focus particularly on the ATP-driven acto-myosin motor that powers invasion. Crown Copyright © 2011. Published by Elsevier Ltd. All rights reserved.

  10. Blood Stage Plasmodium falciparum Exhibits Biological Responses to Direct Current Electric Fields.

    Directory of Open Access Journals (Sweden)

    Lorena M Coronado

    Full Text Available The development of resistance to insecticides by the vector of malaria and the increasingly faster appearance of resistance to antimalarial drugs by the parasite can dangerously hamper efforts to control and eradicate the disease. Alternative ways to treat this disease are urgently needed. Here we evaluate the in vitro effect of direct current (DC capacitive coupling electrical stimulation on the biology and viability of Plasmodium falciparum. We designed a system that exposes infected erythrocytes to different capacitively coupled electric fields in order to evaluate their effect on P. falciparum. The effect on growth of the parasite, replication of DNA, mitochondrial membrane potential and level of reactive oxygen species after exposure to electric fields demonstrate that the parasite is biologically able to respond to stimuli from DC electric fields involving calcium signaling pathways.

  11. Gibberellin Biosynthetic Inhibitors Make Human Malaria Parasite Plasmodium falciparum Cells Swell and Rupture to Death

    Science.gov (United States)

    Toyama, Tomoko; Tahara, Michiru; Nagamune, Kisaburo; Arimitsu, Kenji; Hamashima, Yoshio; Palacpac, Nirianne M. Q.; Kawaide, Hiroshi; Horii, Toshihiro; Tanabe, Kazuyuki

    2012-01-01

    Malaria remains as one of the most devastating infectious disease, and continues to exact an enormous toll in medical cost and days of labor lost especially in the tropics. Effective malaria control and eventual eradication remain a huge challenge, with efficacious antimalarials as important intervention/management tool. Clearly new alternative drugs that are more affordable and with fewer side effects are desirable. After preliminary in vitro assays with plant growth regulators and inhibitors, here, we focus on biosynthetic inhibitors of gibberellin, a plant hormone with many important roles in plant growth, and show their inhibitory effect on the growth of both apicomplexa, Plasmodium falciparum and Toxoplasma gondii. Treatment of P. falciparum cultures with the gibberellin biosynthetic inhibitors resulted in marked morphological changes that can be reversed to a certain degree under hyperosmotic environment. These unique observations suggest that changes in the parasite membrane permeability may explain the pleiotropic effects observed within the intracellular parasites. PMID:22412858

  12. Plate-based transfection and culturing technique for genetic manipulation of Plasmodium falciparum

    Science.gov (United States)

    2012-01-01

    Genetic manipulation of malaria parasites remains an inefficient, time-consuming and resource-intensive process. Presented here is a set of methods for 96-well plate-based transfection and culture that improve the efficiency of genetic manipulation of Plasmodium falciparum. Compared to standard protocols plate-based transfection requires 20-fold less DNA, transient transfection efficiency achieved is approximately seven-fold higher, whilst stable transfection success rate is above 90%. Furthermore the utility of this set of protocols to generate a knockout of the PfRH3 pseudogene, screened by whole-cell PCR, is demonstrated. The methods and tools presented here will facilitate genome-scale genetic manipulation of P. falciparum. PMID:22257490

  13. The exported chaperone Hsp70-x supports virulence functions for Plasmodium falciparum blood stage parasites.

    Directory of Open Access Journals (Sweden)

    Sarah C Charnaud

    Full Text Available Malaria is caused by five different Plasmodium spp. in humans each of which modifies the host erythrocyte to survive and replicate. The two main causes of malaria, P. falciparum and P. vivax, differ in their ability to cause severe disease, mainly due to differences in the cytoadhesion of infected erythrocytes (IE in the microvasculature. Cytoadhesion of P. falciparum in the brain leads to a large number of deaths each year and is a consequence of exported parasite proteins, some of which modify the erythrocyte cytoskeleton while others such as PfEMP1 project onto the erythrocyte surface where they bind to endothelial cells. Here we investigate the effects of knocking out an exported Hsp70-type chaperone termed Hsp70-x that is present in P. falciparum but not P. vivax. Although the growth of Δhsp70-x parasites was unaffected, the export of PfEMP1 cytoadherence proteins was delayed and Δhsp70-x IE had reduced adhesion. The Δhsp70-x IE were also more rigid than wild-type controls indicating changes in the way the parasites modified their host erythrocyte. To investigate the cause of this, transcriptional and translational changes in exported and chaperone proteins were monitored and some changes were observed. We propose that PfHsp70-x is not essential for survival in vitro, but may be required for the efficient export and functioning of some P. falciparum exported proteins.

  14. [Molecular epidemiological surveillance of markers for antimalarial drugs in Plasmodium falciparum isolates imported to Barcelona, Spain].

    Science.gov (United States)

    Gascón, Joaquim; Mayor, Alfredo; Mühlberger, Nikolai; Peyerl-Hoffmann, Gabriele; Oliveira, I; Dobaño, Carlota; Jelinek, Tomas; Corachan, Manuel

    2005-09-10

    There have been described compelling correlations between mutations in some Plasmodium falciparum genes and resistance to antimalarial drugs. To apply molecular techniques in the mechanisms of epidemiological surveillance in the Hospital Clínic of Barcelona and to map potential levels of resistance, we investigated the presence of mutations in the relevant codons of genes associated with resistance in P. falciparum isolates imported by travellers. The genes pfctr, pfmdr1, dhfr, dhps and cytochrome b were analyzed by PCR and enzymatic restriction in P. falciparum isolates from 53 persons attending the Tropical Medicine Department after a trip to a malaria endemic area. 63% of patients were infected with a P. falciparum isolate with the K76T mutation in pfctr. Tyr86 in pfmdr1 was found in 54% of the isolates. Mutations in codons 51, 59 and 108 in dhfr were found in 33%, 49% and 44% of the isolates, respectively. Mutations in codons 436, 437 and 540 in dhps were found in 35%, 35% and 8.5% of the isolates. 30% of travellers were infected by parasites displaying 3 or more mutations in any of the codons of dhps and dhfr. None of the patients had a mutation in the Tyr268 codon of the cytochrome B gene. The high prevalence of mutations in the imported isolates suggests a fast development and expansion of resistance against most of the antimalarial drugs commonly used. The concurrence of more than one mutation in different loci suggests the expansion of multiple resistances.

  15. Limited Geographical Origin and Global Spread of Sulfadoxine-Resistant dhps Alleles in Plasmodium falciparum Populations

    Science.gov (United States)

    Venkatesan, Meera; Ohashi, Jun; Culleton, Richard; Takahashi, Nobuyuki; Tsukahara, Takahiro; Ndounga, Mathieu; Dysoley, Lek; Endo, Hiroyoshi; Hombhanje, Francis; Ferreira, Marcelo U.; Plowe, Christopher V.; Tanabe, Kazuyuki

    2011-01-01

    Background. Plasmodium falciparum malaria resistant to chloroquine and pyrimethamine originated in limited foci and migrated to Africa. It remains unresolved whether P. falciparum resistance to sulfadoxine, which is conferred by mutations in dihydropteroate synthase (DHPS), evolved following a similar pattern. Methods. The dhps locus of 893 P. falciparum isolates from 12 countries in Asia, the Pacific Islands, Africa, and South America was sequenced. Haplotypes of 6 microsatellite loci flanking the dhps locus were determined to define the genetic relationships among sulfadoxine-resistant lineages. Results. Six distinct sulfadoxine-resistant lineages were identified. Highly resistant lineages appear to have originated only in Southeast Asia and South America. Two resistant lineages found throughout Southeast Asia have been introduced to East Africa, where they appear to have spread. Conclusions. The infrequent selection of parasites highly resistant to sulfadoxine and the subsequent migration of resistant lineages from Asia to Africa are similar to the patterns observed in chloroquine and pyrimethamine resistance. These findings strongly suggest that the global migration of resistant parasites has played a decisive role in the establishment of drug-resistant P. falciparum parasites, and that similar patterns may be anticipated for the spread of artemisinin resistance. PMID:22021623

  16. Plasmodium falciparum produces prostaglandins that are pyrogenic, somnogenic, and immunosuppressive substances in humans.

    Science.gov (United States)

    Kilunga Kubata, B; Eguchi, N; Urade, Y; Yamashita, K; Mitamura, T; Tai, K; Hayaishi, O; Horii, T

    1998-09-21

    Plasmodium falciparum causes the most severe form of human malaria, which kills approximately 1.5-2.7 million people every year, but the molecular mechanisms underlying the clinical symptoms and the host-parasite interaction remain unclear. We show here that P. falciparum produces prostaglandins (PGs) D2, E2, and F2alpha. After incubation with 1 mM arachidonic acid (AA), cell homogenates of P. falciparum produced PGs as determined by enzyme immunoassay and gas chromatography-selected ion monitoring. PG production in the parasite homogenate was not affected by the nonsteroidal antiinflammatory drugs aspirin and indomethacin, and was partially heat resistant, whereas PG biosynthesis by mammalian cyclooxygenase was completely inhibited by these chemicals and by heat treatment. Addition of AA to the parasite cell culture markedly increased an ability of the parasite cell homogenate to produce PGs and of parasitized red blood cells to accumulate PGs in the culture medium. PGD2 and PGE2 accumulated in the culture medium at the stages of trophozoites and schizonts more actively than at the ring stage. These findings are the first evidence of the direct involvement of a malaria parasite in the generation of substances that are pyrogenic and injurious to the host defenses. We will discuss a possible contribution of the parasite-produced PGs to pathogenesis and host-parasite interaction of P. falciparum.

  17. Plasmodium falciparum: stage specific effects of a selective inhibitor of lactate dehydrogenase.

    Science.gov (United States)

    Vivas, Livia; Easton, Anna; Kendrick, Howard; Cameron, Angus; Lavandera, Jose-Luis; Barros, David; de las Heras, Federico Gomez; Brady, R Leo; Croft, Simon L

    2005-10-01

    Plasmodium falciparum lactate dehydrogenase (PfLDH) is essential for ATP generation. Based on structural differences within the active site between P. falciparum and human LDH, we have identified a series of heterocyclic azole-based inhibitors that selectively bind within the PfLDH but not the human LDH (hLDH) active site and showed anti-malarial activity in vitro and in vivo. Here we expand on an azole, OXD1, from this series and found that the anti-P. falciparum activity was retained against a panel of strains independently of their anti-malarial drug sensitivity profile. Trophozoites had relatively higher PfLDH enzyme activity and PfLDH-RNA expression levels than rings and were the most susceptible stages to OXD1 exposure. This is probably linked to their increased energy requirements and consistent with glycolysis being an essential metabolic pathway for parasite survival within the erythrocyte. Further structural elaboration of these azoles could lead to the identification of compounds that target P. falciparum through such a novel mechanism and with more potent anti-malarial activity.

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

    Science.gov (United States)

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

    2016-01-01

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

  19. Specific tagging of the egress-related osmiophilic bodies in the gametocytes of Plasmodium falciparum

    Directory of Open Access Journals (Sweden)

    Sannella Anna

    2012-03-01

    Full Text Available Abstract Background Gametocytes, the blood stages responsible for Plasmodium falciparum transmission, contain electron dense organelles, traditionally named osmiophilic bodies, that are believed to be involved in gamete egress from the host cell. In order to provide novel tools in the cellular and molecular studies of osmiophilic body biology, a P. falciparum transgenic line in which these organelles are specifically marked by a reporter protein was produced and characterized. Methodology A P. falciparum transgenic line expressing an 80-residue N-terminal fragment of the osmiophilic body protein Pfg377 fused to the reporter protein DsRed, under the control of pfg377 upstream and downstream regulatory regions, was produced. Results The transgenic fusion protein is expressed at the appropriate time and stage of sexual differentiation and is trafficked to osmiophilic bodies as the endogenous Pfg377 protein. These results indicate that a relatively small N-terminal portion of Pfg377 is sufficient to target the DsRed reporter to the gametocyte osmiophilic bodies. Conclusions This is the first identification of a P. falciparum aminoacid sequence able to mediate trafficking to such organelles. To fluorescently tag such poorly characterized organelles opens novel avenues in cellular and imaging studies on their biogenesis and on their role in gamete egress.

  20. The transmembrane isoform of Plasmodium falciparum MAEBL is essential for the invasion of Anopheles salivary glands.

    Directory of Open Access Journals (Sweden)

    Fabian E Saenz

    Full Text Available Malaria transmission depends on infective stages in the mosquito salivary glands. Plasmodium sporozoites that mature in midgut oocysts must traverse the hemocoel and invade the mosquito salivary glands in a process thought to be mediated by parasite ligands. MAEBL, a homologue of the transmembrane EBP ligands essential in merozoite invasion, is expressed abundantly in midgut sporozoites. Alternative splicing generates different MAEBL isoforms and so it is unclear what form is functionally essential. To identify the MAEBL isoform required for P. falciparum (NF54 sporozoite invasion of salivary glands, we created knockout and allelic replacements each carrying CDS of a single MAEBL isoform. Only the transmembrane form of MAEBL is essential and is the first P. falciparum ligand validated as essential for invasion of Anopheles salivary glands. MAEBL is the first P. falciparum ligand experimentally determined to be essential for this important step in the life cycle where the vector becomes infectious for transmitting sporozoites to people. With an increasing emphasis on advancing vector-based transgenic methods for suppression of malaria, it is important that this type of study, using modern molecular genetic tools, is done with the agent of the human disease. Understanding what P. falciparum sporozoite ligands are critical for mosquito transmission will help validate targets for vector-based transmission-blocking strategies.

  1. Role of Calcium Signaling in the Transcriptional Regulation of the Apicoplast Genome of Plasmodium falciparum

    Directory of Open Access Journals (Sweden)

    Sabna Cheemadan

    2014-01-01

    Full Text Available Calcium is a universal second messenger that plays an important role in regulatory processes in eukaryotic cells. To understand calcium-dependent signaling in malaria parasites, we analyzed transcriptional responses of Plasmodium falciparum to two calcium ionophores (A23187 and ionomycin that cause redistribution of intracellular calcium within the cytoplasm. While ionomycin induced a specific transcriptional response defined by up- or downregulation of a narrow set of genes, A23187 caused a developmental arrest in the schizont stage. In addition, we observed a dramatic decrease of mRNA levels of the transcripts encoded by the apicoplast genome during the exposure of P. falciparum to both calcium ionophores. Neither of the ionophores caused any disruptions to the DNA replication or the overall apicoplast morphology. This suggests that the mRNA downregulation reflects direct inhibition of the apicoplast gene transcription. Next, we identify a nuclear encoded protein with a calcium binding domain (EF-hand that is localized to the apicoplast. Overexpression of this protein (termed PfACBP1 in P. falciparum cells mediates an increased resistance to the ionophores which suggests its role in calcium-dependent signaling within the apicoplast. Our data indicate that the P. falciparum apicoplast requires calcium-dependent signaling that involves a novel protein PfACBP1.

  2. Crystal structure of fructose-1,6-bisphosphate aldolase from the human malaria parasite Plasmodium falciparum.

    Science.gov (United States)

    Kim, H; Certa, U; Döbeli, H; Jakob, P; Hol, W G

    1998-03-31

    The structure of the glycolytic enzyme class I fructose-1, 6-bisphosphate aldolase from the human malaria parasite Plasmodium falciparum has been determined by X-ray crystallography. Homotetrameric P. falciparum aldolase (PfALDO) crystallizes in space group P3221 with one 80 kDa dimer per asymmetric unit. The final refined PfALDO model has an R-factor of 0.239 and an R-free of 0.329 with respect to data from 8 to 3.0 A resolution. PfALDO is potentially a target for antimalarial drug design as the intraerythrocytic merozoite lifestage of P. falciparum is completely dependent upon glycolysis for its ATP production. Thus, inhibitors directed against the glycolytic enzymes in P. falciparum may be effective in killing the parasite. The structure of PfALDO is compared with the previously determined structure of human aldolase in order to determine possible targets for the structure-based design of selective PfALDO ligands. The salient structural differences include a hydrophobic pocket on the surface of PfALDO, which results from some amino acid changes and a single residue deletion compared with human aldolase, and the overall quaternary structure of the PfALDO tetramer, which buries less surface area than human aldolase.

  3. Hemoglobinopathic Erythrocytes Affect the Intraerythrocytic Multiplication of Plasmodium falciparum In Vitro

    Science.gov (United States)

    Glushakova, Svetlana; Balaban, Amanda; McQueen, Philip G.; Coutinho, Rosane; Miller, Jeffery L.; Nossal, Ralph; Fairhurst, Rick M.; Zimmerberg, Joshua

    2014-01-01

    Background. The mechanisms by which α-thalassemia and sickle cell traits confer protection from severe Plasmodium falciparum malaria are not yet fully elucidated. We hypothesized that hemoglobinopathic erythrocytes reduce the intraerythrocytic multiplication of P. falciparum, potentially delaying the development of life-threatening parasite densities until parasite clearing immunity is achieved. Methods. We developed a novel in vitro assay to quantify the number of merozoites released from an individual schizont, termed the “intraerythrocytic multiplication factor” (IMF). Results. P. falciparum (3D7 line) schizonts produce variable numbers of merozoites in all erythrocyte types tested, with median IMFs of 27, 27, 29, 23, and 23 in control, HbAS, HbSS, and α- and β-thalassemia trait erythrocytes, respectively. IMF correlated strongly (r2 = 0.97; P erythrocytes was confirmed using clinical parasite isolates with different IMFs. Mathematical modeling of the effect of IMF on malaria progression indicates that the lower IMF in thalassemia trait erythrocytes limits parasite density and anemia severity over the first 2 weeks of parasite replication. Conclusions. P. falciparum IMF, a parasite heritable virulence trait, correlates with erythrocyte indices and is reduced in thalassemia trait erythrocytes. Parasite IMF should be examined in other low-indices erythrocytes. PMID:24688070

  4. DNA Sequence Polymorphism of the Lactate Dehydrogenase Genefrom Iranian Plasmodium vivax and Plasmodium falciparum Isolates.

    Science.gov (United States)

    Getacher Feleke, Daniel; Nateghpour, Mehdi; Motevalli Haghi, Afsaneh; Hajjaran, Homa; Farivar, Leila; Mohebali, Mehdi; Raoofian, Reza

    2015-01-01

    Parasite lactate dehydrogenase (pLDH) is extensively employed as malaria rapid diagnostic tests (RDTs). Moreover, it is a well-known drug target candidate. However, the genetic diversity of this gene might influence performance of RDT kits and its drug target candidacy. This study aimed to determine polymorphism of pLDH gene from Iranian isolates of P. vivax and P. falciparum. Genomic DNA was extracted from whole blood of microscopically confirmed P. vivax and P. falciparum infected patients. pLDH gene of P. falciparum and P. vivax was amplified using conventional PCR from 43 symptomatic malaria patients from Sistan and Baluchistan Province, Southeast Iran from 2012 to 2013. Sequence analysis of 15 P. vivax LDH showed fourteen had 100% identity with P. vivax Sal-1 and Belem strains. Two nucleotide substitutions were detected with only one resulted in amino acid change. Analysis of P. falciparum LDH sequences showed six of the seven sequences had 100% homology with P. falciparum 3D7 and Mzr-1. Moreover, PfLDH displayed three nucleotide changes that resulted in changing only one amino acid. PvLDH and PfLDH showed 75%-76% nucleotide and 90.4%-90.76% amino acid homology. pLDH gene from Iranian P. falciparum and P. vivax isolates displayed 98.8-100% homology with 1-3 nucleotide substitutions. This indicated this gene was relatively conserved. Additional studies can be done weather this genetic variation can influence the performance of pLDH based RDTs or not.

  5. Genetic diversity of vaccine candidate antigens in Plasmodium falciparum isolates from the Amazon basin of Peru

    Directory of Open Access Journals (Sweden)

    Lucas Carmen M

    2008-05-01

    Full Text Available Abstract Background Several of the intended Plasmodium falciparum vaccine candidate antigens are highly polymorphic and could render a vaccine ineffective if their antigenic sites were not represented in the vaccine. In this study, characterization of genetic variability was performed in major B and T-cell epitopes within vaccine candidate antigens in isolates of P. falciparum from Peru. Methods DNA sequencing analysis was completed on 139 isolates of P. falciparum collected from endemic areas of the Amazon basin in Loreto, Peru from years 1998 to 2006. Genetic diversity was determined in immunological important regions in circumsporozoite protein (CSP, merozoite surface protein-1 (MSP-1, apical membrane antigen-1 (AMA-1, liver stage antigen-1 (LSA-1 and thrombospondin-related anonymous protein (TRAP. Alleles identified by DNA sequencing were aligned with the vaccine strain 3D7 and DNA polymorphism analysis and FST study-year pairwise comparisons were done using the DnaSP software. Multilocus analysis (MLA was performed and average of expected heterozygosity was calculated for each loci and haplotype over time. Results Three different alleles for CSP, seven for MSP-1 Block 2, one for MSP-1 Block 17, three for AMA-1 and for LSA-1 each and one for TRAP were identified. There were 24 different haplotypes in 125 infections with complete locus typing for each gene. Conclusion Characterization of the genetic diversity in Plasmodium isolates from the Amazon Region of Peru showed that P. falciparum T and B cell epitopes in these antigens have polymorphisms more similar to India than to Africa. These findings are helpful in the formulation of a vaccine considering restricted repertoire populations.

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

    Science.gov (United States)

    2010-01-01

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

  7. Plasmodium falciparum normocyte binding protein (PfNBP-1) peptides bind specifically to human erythrocytes.

    Science.gov (United States)

    Valbuena, John Jairo; Vera, Ricardo; García, Javier; Puentes, Alvaro; Curtidor, Hernando; Ocampo, Marisol; Urquiza, Mauricio; Rivera, Zuly; Guzmán, Fanny; Torres, Elizabeth; Patarroyo, Manuel Elkin

    2003-07-01

    Plasmodium falciparum normocyte binding protein-1 (PfNBP-1), a Plasmodium vivax RBP-1 orthologue is expressed in the apical merozoite area. PfNBP-1 binds directly to human erythrocyte membrane in a sialic acid-dependent but trypsin-resistant way. Erythrocyte binding assays were done with synthetic peptides covering the sequence reported as PfNBP-1. Two specific erythrocyte high activity binding peptides were found: 101VFINDLDTYQYEYFYEWNQ(120), peptide 26332, and 181NTKETYLKELNKKKMLQNKK(200), peptide 26336. These two peptides' binding was saturable and presenting nanomolar affinity constants. The critical binding residues (those residues underlined and highlighted in bold) were determined by competition assays with glycine-scan analogue peptides. These peptides were able to block merozoite in vitro invasion of erythrocytes.

  8. Malaria-induced acquisition of antibodies to Plasmodium falciparum variant surface antigens

    DEFF Research Database (Denmark)

    Ofori, Michael F; Dodoo, Daniel; Staalsoe, Trine

    2002-01-01

    In areas of intense Plasmodium falciparum transmission, protective immunity is acquired during childhood in parallel with acquisition of agglutinating antibodies to parasite-encoded variant surface antigens (VSA) expressed on parasitized red blood cells. In a semi-immune child in such an area......, clinical disease is caused mainly by parasites expressing VSA not recognized by preexisting VSA-specific antibodies in that child. Such malaria episodes are known to cause an increase in agglutinating antibodies specifically recognizing VSA expressed by the parasite isolate causing the illness, whereas...

  9. Crystal structure of phosphoethanolamine methyltransferase from Plasmodium falciparum in complex with amodiaquine

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Soon Goo; Alpert, Tara D.; Jez, Joseph M. (WU)

    2012-07-17

    Phosphoethanolamine N-methyltransferase (PMT) is essential for phospholipid biogenesis in the malarial parasite Plasmodium falciparum. PfPMT catalyzes the triple methylation of phosphoethanolamine to produce phosphocholine, which is then used for phosphatidylcholine synthesis. Here we describe the 2.0 {angstrom} resolution X-ray crystal structure of PfPMT in complex with amodiaquine. To better characterize inhibition of PfPMT by amodiaquine, we determined the IC{sub 50} values of a series of aminoquinolines using a direct radiochemical assay. Both structural and functional analyses provide a possible approach for the development of new small molecule inhibitors of PfPMT.

  10. A four-year surveillance program for detection of Plasmodium falciparum chloroquine resistance in Honduras

    Directory of Open Access Journals (Sweden)

    Gustavo A Fontecha

    2014-07-01

    Full Text Available Countries could use the monitoring of drug resistance in malaria parasites as an effective early warning system to develop the timely response mechanisms that are required to avert the further spread of malaria. Drug resistance surveillance is essential in areas where no drug resistance has been reported, especially if neighbouring countries have previously reported resistance. Here, we present the results of a four-year surveillance program based on the sequencing of the pfcrt gene of Plasmodium falciparum populations from endemic areas of Honduras. All isolates were susceptible to chloroquine, as revealed by the pfcrt “CVMNK” genotype in codons 72-76.

  11. Cytokine production and apoptosis among T cells from patients under treatment for Plasmodium falciparum malaria

    DEFF Research Database (Denmark)

    Kemp, K; Akanmori, B D; Adabayeri, V

    2002-01-01

    Available evidence suggests that Plasmodium falciparum malaria causes activation and reallocation of T cells, and that these in vivo primed cells re-emerge into the periphery following drug therapy. Here we have examined the cytokine production capacity and susceptibility to programmed cell death...... cells was elevated at admission and peaked 2 days later, while susceptibility to activation-induced cell death in vitro remained increased for at least 1 week after admission. Taken together, the data are consistent with the concept of malaria-induced reallocation of activated T cells to sites...

  12. Reversible suppression of bone marrow response to erythropoietin in Plasmodium falciparum malaria

    DEFF Research Database (Denmark)

    Kurtzhals, J A; Rodrigues, O; Addae, M

    1997-01-01

    To study the importance of bone marrow inhibition in the pathogenesis of malarial anaemia, haematological and parasitological parameters were followed in patients with acute malaria. Three patient categories were studied, severe malarial anaemia (SA), cerebral malaria (CM) and uncomplicated malaria...... clearance RDW increased dramatically, reaching the highest levels 1-2 weeks later. Although severe anaemia was corrected by blood transfusion during the first 3 d of treatment, the peak RDW correlated significantly with the initial EPO levels. This suggests that Plasmodium falciparum infection causes...

  13. Induction of cell death on Plasmodium falciparum asexual blood stages by Solanum nudum steroids

    DEFF Research Database (Denmark)

    López, Mary Luz; Vommaro, Rossiane; Zalis, Mariano

    2010-01-01

    Solanum nudum Dunal (Solanaceae) is a plant used in traditional medicine in Colombian Pacific Coast, from which five steroids denominated SNs have been isolated. The SNs compounds have antiplasmodial activity against asexual blood stages of Plasmodium falciparum strain 7G8 with an IC50 between 20...... found that trophozoite and schizont stages were the most sensitive to SNs. By Giemsa-stained smears, induction of crisis forms was observed. Transmission electron microscopy of treated parasites showed morphological abnormalities such as a cytoplasm rich in vesicles and myelinic figures...

  14. RIFINs are adhesins implicated in severe Plasmodium falciparum malaria

    DEFF Research Database (Denmark)

    Goel, Suchi; Palmkvist, Mia; Moll, Kirsten

    2015-01-01

    Rosetting is a virulent Plasmodium falciparum phenomenon associated with severe malaria. Here we demonstrate that P. falciparum–encoded repetitive interspersed families of polypeptides (RIFINs) are expressed on the surface of infected red blood cells (iRBCs), where they bind to RBCs......—preferentially of blood group A—to form large rosettes and mediate microvascular binding of iRBCs. We suggest that RIFINs have a fundamental role in the development of severe malaria and thereby contribute to the varying global distribution of ABO blood groups in the human population....

  15. Geographical and temporal conservation of antibody recognition of Plasmodium falciparum variant surface antigens

    DEFF Research Database (Denmark)

    Nielsen, Morten A; Vestergaard, Lasse S; Lusingu, John

    2004-01-01

    The slow acquisition of protection against Plasmodium falciparum malaria probably reflects the extensive diversity of important antigens. The variant surface antigens (VSA) that mediate parasite adhesion to a range of host molecules are regarded as important targets of acquired protective immunity...... (VSASM) that were better recognized by plasma IgG than VSA expressed by other parasites, but importantly, VSASM-type antigens also appeared to show substantial antigenic homogeneity. Our finding that the repertoire of immunologically distinct VSA in general, and in particular that of VSASM...

  16. Thrombin Cleavage of Plasmodium falciparum Erythrocyte Membrane Protein 1 Inhibits Cytoadherence.

    Science.gov (United States)

    Gillrie, Mark R; Renaux, Bernard; Russell-Goldman, Eleanor; Avril, Marion; Brazier, Andrew J; Mihara, Koichiro; Di Cera, Enrico; Milner, Danny A; Hollenberg, Morley D; Smith, Joseph D; Ho, May

    2016-09-13

    Plasmodium falciparum malaria remains one of the most deadly infections worldwide. The pathogenesis of the infection results from the sequestration of infected erythrocytes (IRBC) in vital organs, including the brain, with resulting impairment of blood flow, hypoxia, and lactic acidosis. Sequestration occurs through the adhesion of IRBC to host receptors on microvascular endothelium by Plasmodium falciparum erythrocyte membrane protein 1 (PfEMP1), a large family of variant surface antigens, each with up to seven extracellular domains that can bind to multiple host receptors. Consequently, antiadhesive therapies directed at single endothelial adhesion molecules may not be effective. In this study, we demonstrated that the serine protease thrombin, which is pivotal in the activation of the coagulation cascade, cleaved the major parasite adhesin on the surface of IRBC. As a result, adhesion under flow was dramatically reduced, and already adherent IRBC were detached. Thrombin cleavage sites were mapped to the Duffy binding-like δ1 (DBLδ1) domain and interdomains 1 and 2 in the PfEMP1 of the parasite line IT4var19. Furthermore, we observed an inverse correlation between the presence of thrombin and IRBC in cerebral malaria autopsies of children. We investigated a modified (R67A) thrombin and thrombin inhibitor, hirugen, both of which inhibit the binding of substrates to exosite I, thereby reducing its proinflammatory properties. Both approaches reduced the barrier dysfunction induced by thrombin without affecting its proteolytic activity on PfEMP1, raising the possibility that thrombin cleavage of variant PfEMP1 may be exploited as a broadly inhibitory antiadhesive therapy. Plasmodium falciparum malaria is the third leading cause of mortality due to a pathogen, with 214 million people infected and 438,000 deaths annually. The adhesion of Plasmodium falciparum-infected erythrocytes (IRBC) to microvascular endothelium is a major pathological process in severe malaria

  17. Interconvertible geometric isomers of Plasmodium falciparum dihydroorotate dehydrogenase inhibitors exhibit multiple binding modes.

    Science.gov (United States)

    McConkey, Glenn A; Bedingfield, Paul T P; Burrell, David R; Chambers, Nicholas C; Cunningham, Fraser; Prior, Timothy J; Fishwick, Colin W G; Boa, Andrew N

    2017-08-15

    Two new tricyclic β-aminoacrylate derivatives (2e and 3e) have been found to be inhibitors of Plasmodium falciparum dihydroorotate dehydrogenase (PfDHODH) with Ki 0.037 and 0.15μM respectively. 1H and 13C NMR spectroscopic data show that these compounds undergo ready cis-trans isomerisation at room temperature in polar solvents. In silico docking studies indicate that for both molecules there is neither conformation nor double bond configuration which bind preferentially to PfDHODH. This flexibility is favourable for inhibitors of this channel that require extensive positioning to reach their binding site. Copyright © 2017 Elsevier Ltd. All rights reserved.

  18. Distribution pattern of Plasmodium falciparum chloroquine transporter (pfcrt) gene haplotypes in Sri Lanka 1996-2006

    DEFF Research Database (Denmark)

    Zhang, Jenny J; Senaratne, Tharanga N; Daniels, Rachel

    2011-01-01

    Abstract. Widespread antimalarial resistance has been a barrier to malaria elimination efforts in Sri Lanka. Analysis of genetic markers in historic parasites may uncover trends in the spread of resistance. We examined the frequency of Plasmodium falciparum chloroquine transporter (pfcrt; codons 72......-76) haplotypes in Sri Lanka in 1996-1998 and 2004-2006 using a high-resolution melting assay. Among 59 samples from 1996 to 1998, we detected the SVMNT (86%), CVMNK (10%), and CVIET (2%) haplotypes, with a positive trend in SVMNT and a negative trend in CVMNK frequency (P = 0.004) over time. Among 24 samples...

  19. Significance of circumsporozoite-specific antibody in the natural transmission of Plasmodium falciparum, Plasmodium vivax, and Plasmodium malariae in an aboriginal (Orang Asli) population of central peninsula Malaysia.

    Science.gov (United States)

    Gordon, D M; Davis, D R; Lee, M; Lambros, C; Harrison, B A; Samuel, R; Campbell, G H; Jegathesan, M; Selvarajan, K; Lewis, G E

    1991-07-01

    Two hundred and seventy-five Orang Asli volunteers living in nine villages in the Pos Legap Valley of Perak State, peninsular Malaysia, participated in a prospective study designed to characterize the epidemiological, parasitological, and entomological characteristics of Plasmodium falciparum, P. vivax, and P. malariae malaria transmission. Prevalence rates for the three plasmodial species at initiation of the study ranged from 56% in the 0-4-year-old age group to 0% in individuals over the age of 40. Entomological surveys were conducted, enabling us to determine mosquito salivary gland-positive rates and entomological inoculation rates of 1.2 infectious mosquito bites per person per month for P. falciparum, 2.4 for P. vivax, and 0.3 for P. malariae. Cumulative incidence rates over the 16 weeks of the study, following radical cure of all volunteers, were 22.5% for P. falciparum, 12.7% for P. vivax, and 1.5% for P. malariae. The median baseline antibody titer against the immunodominant repetitive B cell epitope of P. falciparum or P. vivax circumsporozoite protein was significantly higher for volunteers who did not become parasitemic. Volunteers were selected for further study if they had evidence of being challenged with P. falciparum sporozoites during the study, based on a two-fold or greater increase in antibody titer against the immunodominant repetitive B cell epitope of the circumsporozoite protein. Resistance to infection was seen in six of 10 individuals who had high (greater than 25 OD units) baseline ELISA titers, compared with only three of 24 individuals who had low baseline ELISA titers (chi 2 P less than 0.02). A similar analysis for P. vivax did not show a significant correlation.

  20. A highly conserved segmental duplication in the subtelomeres of Plasmodium falciparum chromosomes varies in copy number

    Directory of Open Access Journals (Sweden)

    Ribacke Ulf

    2008-03-01

    Full Text Available Abstract Background Segmental duplications (SD have been found in genomes of various organisms, often accumulated at the ends of chromosomes. It has been assumed that the sequence homology in-between the SDs allow for ectopic interactions that may contribute to the emergence of new genes or gene variants through recombinatorial events. Methods In silico analysis of the 3D7 Plasmodium falciparum genome, conducted to investigate the subtelomeric compartments, led to the identification of subtelomeric SDs. Sequence variation and copy number polymorphisms of the SDs were studied by DNA sequencing, real-time quantitative PCR (qPCR and fluorescent in situ hybridization (FISH. The levels of transcription and the developmental expression of copy number variant genes were investigated by qPCR. Results A block of six genes of >10 kilobases in size, including var, rif, pfmc-2tm and three hypothetical genes (n-, o- and q-gene, was found duplicated in the subtelomeric regions of chromosomes 1, 2, 3, 6, 7, 10 and 11 (SD1. The number of SD1 per genome was found to vary from 4 to 8 copies in between different parasites. The intragenic regions of SD1 were found to be highly conserved across ten distinct fresh and long-term cultivated P. falciparum. Sequence variation was detected in a ≈ 23 amino-acid long hypervariable region of a surface-exposed loop of PFMC-2TM. A hypothetical gene within SD1, the n-gene, encoding a PEXEL/VTS-containing two-transmembrane protein was found expressed in ring stage parasites. The n-gene transcription levels were found to correlate to the number of n-gene copies. Fragments of SD1 harbouring two or three of the SD1-genes (o-gene, pfmc-2tm, q-gene were also found in the 3D7 genome. In addition a related second SD, SD2, of ≈ 55% sequence identity to SD1 was found duplicated in a fresh clinical isolate but was only present in a single copy in 3D7 and in other P. falciparum lines or clones. Conclusion Plasmodium falciparum carries

  1. Rapid detection of Plasmodium falciparum with isothermal recombinase polymerase amplification and lateral flow analysis

    Science.gov (United States)

    2014-01-01

    Background Nucleic acid amplification is the most sensitive and specific method to detect Plasmodium falciparum. However the polymerase chain reaction remains laboratory-based and has to be conducted by trained personnel. Furthermore, the power dependency for the thermocycling process and the costly equipment necessary for the read-out are difficult to cover in resource-limited settings. This study aims to develop and evaluate a combination of isothermal nucleic acid amplification and simple lateral flow dipstick detection of the malaria parasite for point-of-care testing. Methods A specific fragment of the 18S rRNA gene of P. falciparum was amplified in 10 min at a constant 38°C using the isothermal recombinase polymerase amplification (RPA) method. With a unique probe system added to the reaction solution, the amplification product can be visualized on a simple lateral flow strip without further labelling. The combination of these methods was tested for sensitivity and specificity with various Plasmodium and other protozoa/bacterial strains, as well as with human DNA. Additional investigations were conducted to analyse the temperature optimum, reaction speed and robustness of this assay. Results The lateral flow RPA (LF-RPA) assay exhibited a high sensitivity and specificity. Experiments confirmed a detection limit as low as 100 fg of genomic P. falciparum DNA, corresponding to a sensitivity of approximately four parasites per reaction. All investigated P. falciparum strains (n = 77) were positively tested while all of the total 11 non-Plasmodium samples, showed a negative test result. The enzymatic reaction can be conducted under a broad range of conditions from 30-45°C with high inhibitory concentration of known PCR inhibitors. A time to result of 15 min from start of the reaction to read-out was determined. Conclusions Combining the isothermal RPA and the lateral flow detection is an approach to improve molecular diagnostic for P. falciparum in

  2. [Construction of Plasmodium falciparum signal peptide peptidase-GFP mutant and its expression analysis in the malaria parasite].

    Science.gov (United States)

    Li, Xue-rong; Wu, Yin-juan; Shang, Mei; Li, Ye; Xu, Jin; Yu, Xin-bing; Athar, Chishti

    2014-08-01

    To construct recombinant plasmid pSPPcGT which contains signal peptide peptidase gene of Plasmodium falciparum (PJSPP) and GFP, and transfect into P. falciparum (3D7 strain) to obtain mutant parasites which can express PJSPP-GFP. Plasmodium falciparum(3D7 strain) genomic DNA was extracted from cultured malaria parasites. The C-terminal region of PJSPP, an 883 bp gene fragment was amplified by PCR, and then cloned into pPM2GT vector to get recombinant vector pSPPcGT. The recombinant vectors were identified by PCR, double restriction enzyme digestion and DNA sequencing. pSPPcGT vector was transfected into malaria parasites. The positive clones were selected by adding inhibitor of Plasmodium falciparum dihydrofolate reductase WR99210 to the culture medium. The pSPP-GFP-transfected parasites were fixed with methanol, stained with DAPI, and observed under immunofluorescence microscope. The PJSPP-GFP expression in P. falciparum was identified by SDS-PAGE and Western blotting. The C-terminal region of PJSPP was amplified from P.falciparum (3D7 strain) genomic DNA by PCR with the length of 883 bp. The constructed recombinant vectors were identified by PCR screening, double restriction enzyme digestion and DNA sequencing. The pSPPcGT vector was transfected into P. falciparum and the positive clones were selected by WR99210. GFP fluorescence was observed in transfected parasites by immunofluorescence microscopy, and mainly located in the cytoplasm. The PJSPP-GFP expression in malaria parasites was confirmed by Western blotting with a relative molecular mass of Mr 64,000. Recombinant vector PJSPP-GFP is constructed and transfected into P. falciparum to obtain P. falciparum mutant clone which can express PfSPP-GFP.

  3. [In vitro cultivation of Plasmodium falciparum. Applications and limits.- Methodology].

    Science.gov (United States)

    Druilhe, P; Gentilini, M

    1982-01-01

    Five years after Trager and Jensen fixed the requirements for a continuous culture of exo-erythrocytic stages in a semisynthetic medium, major advances have been realized. However all practical applications of this method have not yet been investigated. Its main interest is to offer the observation of the intraerythrocytic asexual multiplication and the beginning of the sexual cycle in monitored conditions, beyond the organism regulating processes, and with endless possibility to modify these conditions according to the necessities of the experiment. Compared with the previous use of expensive monkeys, this culture allows a study of P. falciparum in its natural host, cell, the human erythrocyte. It has been already applied for several investigations: - ultrastructure, metabolism, ADN and ARN sequencies of the parasite itself; - the relations between host and parasite (invasion of the erythrocyte by the merozoïte); - constitutional factors of resistance to malaria (hemoglobin S, C, E, deficiency in G6PD, elliptocytosis); - nutritional factors and immunologic defenses (antibodies, cytotoxic cells, ADCC...); - production of plasmodial antigens at the various erythrocytic stages; - chemotherapy (resistance to antimalarial drugs, screening of new drugs and study of their mode of action). The main disadvantages of Trager's and Jensen's method are for one part it concerns the sole erythrocytic stages and for the other part the parasite growth requires components of human origin (serum and erythrocytes). Human serum is hardly adapted to a standardization and appears as the main cause of variations observed in the in vitro proliferation of the parasite. Erythrocytes have a short survival and their metabolism is difficult to separate from that of the parasite. The minor disadvantages of the culture are: - a relative lack of reproductibility which raises difficulties for interpretation of inhibition tests either by antibodies or by antimalarial drugs; - a low output; - a

  4. Pseudomonas aeruginosa septicaemia in a patient with severe Plasmodium falciparum

    DEFF Research Database (Denmark)

    Kharazmi, A; Høiby, N; Theander, T G

    1987-01-01

    This report describes a Danish patient with severe Plasmodium falciparum infection and Pseudomonas aeruginosa septicaemia. The patient had been sailing along the coast of West Africa for ten years without taking any antimalaria prophylaxis and without any apparent previous history of malaria. He...... presented with severe form of malaria, progressing rapidly into coma and died within a short time. P. aeruginosa was isolated from his blood taken on the day of admission. His neutrophils were all occupied by P. falciparum. The unusual combination of severe falciparum malaria infection and P. aeruginosa...... septicaemia with extensive involvement of neutrophils lends further support for the role of phagocytic defence in malaria....

  5. Aotus infulatus monkey is susceptible to Plasmodium falciparum infection and may constitute an alternative experimental model for malaria

    Directory of Open Access Journals (Sweden)

    Carvalho Leonardo JM

    2000-01-01

    Full Text Available Aotus is one of the WHO-recommended primate models for studies in malaria, and several species can be infected with Plasmodium falciparum or P. vivax. Here we describe the successful infection of the species A. infulatus from eastern Amazon with blood stages of P. falciparum. Both intact and splenectomized animals were susceptible to infection; the intact ones were able to keep parasitemias at lower levels for several days, but developed complications such as severe anemia; splenectomized monkeys developed higher parasitemias but no major complications. We conclude that A. infulatus is susceptible to P. falciparum infection and may represent an alternative model for studies in malaria.

  6. Novel Cross-Border Approaches to Optimise Identification of Asymptomatic and Artemisinin-Resistant Plasmodium Infection in Mobile Populations Crossing Cambodian Borders.

    Directory of Open Access Journals (Sweden)

    Hannah M Edwards

    Full Text Available 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.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.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 these sites to accelerate elimination efforts

  7. Novel Cross-Border Approaches to Optimise Identification of Asymptomatic and Artemisinin-Resistant Plasmodium Infection in Mobile Populations Crossing Cambodian Borders.

    Science.gov (United States)

    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

    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. 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. 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 these sites to accelerate elimination efforts in

  8. Human Gene Expression in Uncomplicated Plasmodium falciparum Malaria.

    Science.gov (United States)

    Colborn, James M; Ylöstalo, Joni H; Koita, Ousmane A; Cissé, Ousmane H; Krogstad, Donald J

    2015-01-01

    To examine human gene expression during uncomplicated P. falciparum malaria, we obtained three samples (acute illness, treatment, and recovery) from 10 subjects and utilized each subject's recovery sample as their baseline. At the time of acute illness (day 1), subjects had upregulation of innate immune response, cytokine, and inflammation-related genes (IL-1β, IL-6, TNF, and IFN-γ), which was more frequent with parasitemias >100,000 per μL and body temperatures ≥ 39°C. Apoptosis-related genes (Fas, BAX, and TP53) were upregulated acutely and for several days thereafter (days 1-3). In contrast, the expression of immune-modulatory (transcription factor 7, HLV-DOA, and CD6) and apoptosis inhibitory (c-myc, caspase 8, and Fas Ligand G) genes was downregulated initially and returned to normal with clinical recovery (days 7-10). These results indicate that the innate immune response, cytokine, and apoptosis pathways are upregulated acutely in uncomplicated malaria with concomitant downregulation of immune-modulatory and apoptosis inhibitory genes.

  9. On the mechanism of chloroquine resistance in Plasmodium falciparum.

    KAUST Repository

    Chinappi, Mauro

    2010-11-19

    Resistance to chloroquine of malaria strains is known to be associated with a parasite protein named PfCRT, the mutated form of which is able to reduce chloroquine accumulation in the digestive vacuole of the pathogen. Whether the protein mediates extrusion of the drug acting as a channel or as a carrier and which is the protonation state of its chloroquine substrate is the subject of a scientific debate. We present here an analytical approach that explores which combination of hypotheses on the mechanism of transport and the protonation state of chloroquine are consistent with available equilibrium experimental data. We show that the available experimental data are not, by themselves, sufficient to conclude whether the protein acts as a channel or as a transporter, which explains the origin of their different interpretation by different authors. Interestingly, though, each of the two models is only consistent with a subset of hypotheses on the protonation state of the transported molecule. The combination of these results with a sequence and structure analysis of PfCRT, which strongly suggests that the molecule is a carrier, indicates that the transported species is either or both the mono and di-protonated forms of chloroquine. We believe that our results, besides shedding light on the mechanism of chloroquine resistance in P. falciparum, have implications for the development of novel therapies against resistant malaria strains and demonstrate the usefulness of an approach combining systems biology strategies with structural bioinformatics and experimental data.

  10. Failure of artesunate-mefloquine combination therapy for uncomplicated Plasmodium falciparum malaria in southern Cambodia

    Directory of Open Access Journals (Sweden)

    Muth Sinuon

    2009-01-01

    Full Text Available Abstract Background Resistance to anti-malarial drugs hampers control efforts and increases the risk of morbidity and mortality from malaria. The efficacy of standard therapies for uncomplicated Plasmodium falciparum and Plasmodium vivax malaria was assessed in Chumkiri, Kampot Province, Cambodia. Methods One hundred fifty-one subjects with uncomplicated falciparum malaria received directly observed therapy with 12 mg/kg artesunate (over three days and 25 mg/kg mefloquine, up to a maximum dose of 600 mg artesunate/1,000 mg mefloquine. One hundred nine subjects with uncomplicated vivax malaria received a total of 25 mg/kg chloroquine, up to a maximum dose of 1,500 mg, over three days. Subjects were followed for 42 days or until recurrent parasitaemia was observed. For P. falciparum infected subjects, PCR genotyping of msp1, msp2, and glurp was used to distinguish treatment failures from new infections. Treatment failure rates at days 28 and 42 were analyzed using both per protocol and Kaplan-Meier survival analysis. Real Time PCR was used to measure the copy number of the pfmdr1 gene and standard 48-hour isotopic hypoxanthine incorporation assays were used to measure IC50 for anti-malarial drugs. Results Among P. falciparum infected subjects, 47.0% were still parasitemic on day 2 and 11.3% on day 3. The PCR corrected treatment failure rates determined by survival analysis at 28 and 42 days were 13.1% and 18.8%, respectively. Treatment failure was associated with increased pfmdr1 copy number, higher initial parasitaemia, higher mefloquine IC50, and longer time to parasite clearance. One P. falciparum isolate, from a treatment failure, had markedly elevated IC50 for both mefloquine (130 nM and artesunate (6.7 nM. Among P. vivax infected subjects, 42.1% suffered recurrent P. vivax parasitaemia. None acquired new P. falciparum infection. Conclusion The results suggest that artesunate-mefloquine combination therapy is beginning to fail in southern

  11. Failure of artesunate-mefloquine combination therapy for uncomplicated Plasmodium falciparum malaria in southern Cambodia.

    Science.gov (United States)

    Rogers, William O; Sem, Rithy; Tero, Thong; Chim, Pheaktra; Lim, Pharath; Muth, Sinuon; Socheat, Duong; Ariey, Frédéric; Wongsrichanalai, Chansuda

    2009-01-12

    Resistance to anti-malarial drugs hampers control efforts and increases the risk of morbidity and mortality from malaria. The efficacy of standard therapies for uncomplicated Plasmodium falciparum and Plasmodium vivax malaria was assessed in Chumkiri, Kampot Province, Cambodia. One hundred fifty-one subjects with uncomplicated falciparum malaria received directly observed therapy with 12 mg/kg artesunate (over three days) and 25 mg/kg mefloquine, up to a maximum dose of 600 mg artesunate/1,000 mg mefloquine. One hundred nine subjects with uncomplicated vivax malaria received a total of 25 mg/kg chloroquine, up to a maximum dose of 1,500 mg, over three days. Subjects were followed for 42 days or until recurrent parasitaemia was observed. For P. falciparum infected subjects, PCR genotyping of msp1, msp2, and glurp was used to distinguish treatment failures from new infections. Treatment failure rates at days 28 and 42 were analyzed using both per protocol and Kaplan-Meier survival analysis. Real Time PCR was used to measure the copy number of the pfmdr1 gene and standard 48-hour isotopic hypoxanthine incorporation assays were used to measure IC50 for anti-malarial drugs. Among P. falciparum infected subjects, 47.0% were still parasitemic on day 2 and 11.3% on day 3. The PCR corrected treatment failure rates determined by survival analysis at 28 and 42 days were 13.1% and 18.8%, respectively. Treatment failure was associated with increased pfmdr1 copy number, higher initial parasitaemia, higher mefloquine IC50, and longer time to parasite clearance. One P. falciparum isolate, from a treatment failure, had markedly elevated IC50 for both mefloquine (130 nM) and artesunate (6.7 nM). Among P. vivax infected subjects, 42.1% suffered recurrent P. vivax parasitaemia. None acquired new P. falciparum infection. The results suggest that artesunate-mefloquine combination therapy is beginning to fail in southern Cambodia and that resistance is not confined to the provinces at

  12. Yeast Dihydroorotate Dehydrogenase as a New Selectable Marker for Plasmodium falciparum Transfection

    Science.gov (United States)

    Ganesan, Suresh M.; Morrisey, Joanne M.; Ke, Hangjun; Painter, Heather J.; Laroiya, Kamal; Phillips, Margaret A.; Rathod, Pradipsinh K.; Mather, Michael W.; Vaidya, Akhil B.

    2011-01-01

    Genetic manipulation of Plasmodium falciparum in culture through transfection has provided numerous insights into the molecular and cell biology of this parasite. The procedure is rather cumbersome, and is limited by the number of drug-resistant markers that can be used for selecting transfected parasites. Here we report a new selectable marker that could allow multiple transfections. We have taken advantage of our finding that a critical function of the mitochondrial electron transport chain (mtETC) in the erythrocytic stages of P. falciparum is the regeneration of ubiquinone as co-substrate of dihydroorotate dehydrogenase (DHODH), and that transgenic P. falciparum expressing ubiquinone-independent DHODH from yeast (yDHODH) are resistant to all mtETC inhibitors. We assessed the possibility of using yDHODH as a positive selectable marker for transfections of P. falciparum, including its use in gene disruption strategies. We constructed a transfection vector designed for gene disruption, termed pUF-1, containing the yDHODH gene as the positive selection marker in combination with a previously described fused yeast cytosine deaminase-uracil phosphoribosyl transferase gene as a negative selection marker. Transfection of the D10 strain followed by selection with atovaquone yielded positively selected parasites containing the plasmid, demonstrating that yDHODH can be used as a selective marker. Atovaquone, however, could not be used for such selection with the Dd2 strain of P. falciparum. On the other hand, we demonstrated that yDHODH transgenic parasites could be selected in both strains by Plasmodium DHODH-specific triazolopyrimidine-based inhibitors. Thus, selection with DHODH inhibitors was superior in that it successfully selected transgenic Dd2 parasites, as well as yielded transgenic parasites after a shorter period of selection. As a proof of concept, we have successfully disrupted the type II vacuolar proton-pumping pyrophosphatase gene (PfVP2) in P. falciparum

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

    Science.gov (United States)

    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

  14. Development of a real-time PCR assay for detection of Plasmodium falciparum, Plasmodium vivax, and Plasmodium ovale for routine clinical diagnosis.

    Science.gov (United States)

    Perandin, F; Manca, N; Calderaro, A; Piccolo, G; Galati, L; Ricci, L; Medici, M C; Arcangeletti, M C; Snounou, G; Dettori, G; Chezzi, C

    2004-03-01

    A TaqMan-based real-time PCR qualitative assay for the detection of three species of malaria parasites-Plasmodium falciparum, P. ovale, and P. vivax-was devised and evaluated using 122 whole-blood samples from patients who had traveled to areas where malaria is endemic and who presented with malaria-like symptoms and fever. The assay was compared to conventional microscopy and to an established nested-PCR assay. The specificity of the new assay was confirmed by sequencing the PCR products from all the positive samples and by the lack of cross-reactivity with Toxoplasma gondii and Leishmania infantum DNA. Real-time PCR assay showed a detection limit (analytical sensitivity) of 0.7, 4, and 1.5 parasites/ micro l for P. falciparum, P. vivax, and P. ovale, respectively. Real-time PCR, like nested PCR, brought to light errors in the species identification by microscopic examination and revealed the presence of mixed infections (P. falciparum plus P. ovale). Real-time PCR can yield results within 2 h, does not require post-PCR processing, reduces sample handling, and minimizes the risks of contamination. The assay can therefore be easily implemented in routine diagnostic malaria tests. Future studies are warranted to investigate the clinical value of this technique.

  15. Prevalence of Dihydrofolate reductase gene mutations in Plasmodium falciparum isolate from pregnant women in Nigeria

    Directory of Open Access Journals (Sweden)

    Olusola Ojurongbe

    2011-12-01

    Full Text Available We assessed the prevalence of Plasmodium falciparum and the frequency of the dhfr triple mutation that is associated with antifolate drug resistance among P. falciparumisolates obtained from pregnant women in Ilorin, Nigeria. The study included 179 women in the second and third trimester of pregnancy who have been exposed to intermittent preventive treatment in pregnancy (IPTp with sulfadoxinepyrimethamine. Thick and thin blood films and PCR were used for malaria parasite detection. Blood group and hemoglobin concentration were also determined. Mutations in P. falciparum dhfr were analyzed by sequencing DNA obtained from blood spots on filter paper. Prevalence of P. falciparum in the population (PCR corrected was 44.1% (79/179 with 66.7% and 33.3% in the second and third trimester, respectively. Primigravide (51.3% were more infected than multigravide (48.7% but the difference was not statistically significant. Women in blood group A had the highest P. falciparum malaria infection (30.8%. The mean hemoglobin concentration was lower among those infected with malaria parasite. Also, more women with the malaria parasite (38.4% had anemia compare to those without (21.4%. The prevalence of the P. falciparum dhfr mutant alleles was 64.1%, 61.5%, 38.5%, and 12.8% for I51, R59, N108 and T108, respectively. None of the samples had the L164 mutation. The combined triple dhfr mutation (51 + 59 + 108 in the population was 17.9% (7 of 39. Also, the prevalence of the triple mutant alleles was not significantly associated to the number of doses of SP taken by the women. These findings highlight the need for a regular assessment of IPTp/SP efficacy, and evaluation of possible alternative drugs.

  16. Genetic Diversity of Plasmodium falciparum in Haiti: Insights from Microsatellite Markers.

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    Tamar E Carter

    Full Text Available Hispaniola, comprising Haiti and the Dominican Republic, has been identified as a candidate for malaria elimination. However, incomplete surveillance data in Haiti hamper efforts to assess the impact of ongoing malaria control interventions. Characteristics of the genetic diversity of Plasmodium falciparum populations can be used to assess parasite transmission, which is information vital to evaluating malaria elimination efforts. Here we characterize the genetic diversity of P. falciparum samples collected from patients at seven sites in Haiti using 12 microsatellite markers previously employed in population genetic analyses of global P. falciparum populations. We measured multiplicity of infections, level of genetic diversity, degree of population geographic substructure, and linkage disequilibrium (defined as non-random association of alleles from different loci. For low transmission populations like Haiti, we expect to see few multiple infections, low levels of genetic diversity, high degree of population structure, and high linkage disequilibrium. In Haiti, we found low levels of multiple infections (12.9%, moderate to high levels of genetic diversity (mean number of alleles per locus = 4.9, heterozygosity = 0.61, low levels of population structure (highest pairwise Fst = 0.09 and no clustering in principal components analysis, and moderate linkage disequilibrium (ISA = 0.05, P<0.0001. In addition, population bottleneck analysis revealed no evidence for a reduction in the P. falciparum population size in Haiti. We conclude that the high level of genetic diversity and lack of evidence for a population bottleneck may suggest that Haiti's P. falciparum population has been stable and discuss the implications of our results for understanding the impact of malaria control interventions. We also discuss the relevance of parasite population history and other host and vector factors when assessing transmission intensity from genetic diversity data.

  17. Sir2 paralogues cooperate to regulate virulence genes and antigenic variation in Plasmodium falciparum.

    Directory of Open Access Journals (Sweden)

    Christopher J Tonkin

    2009-04-01

    Full Text Available Cytoadherance of Plasmodium falciparum-infected erythrocytes in the brain, organs and peripheral microvasculature is linked to morbidity and mortality associated with severe malaria. Parasite-derived P. falciparum Erythrocyte Membrane Protein 1 (PfEMP1 molecules displayed on the erythrocyte surface are responsible for cytoadherance and undergo antigenic variation in the course of an infection. Antigenic variation of PfEMP1 is achieved by in situ switching and mutually exclusive transcription of the var gene family, a process that is controlled by epigenetic mechanisms. Here we report characterisation of the P. falciparum silent information regulator's A and B (PfSir2A and PfSir2B and their involvement in mutual exclusion and silencing of the var gene repertoire. Analysis of P. falciparum parasites lacking either PfSir2A or PfSir2B shows that these NAD(+-dependent histone deacetylases are required for silencing of different var gene subsets classified by their conserved promoter type. We also demonstrate that in the absence of either of these molecules mutually exclusive expression of var genes breaks down. We show that var gene silencing originates within the promoter and PfSir2 paralogues are involved in cis spreading of silenced chromatin into adjacent regions. Furthermore, parasites lacking PfSir2A but not PfSir2B have considerably longer telomeric repeats, demonstrating a role for this molecule in telomeric end protection. This work highlights the pivotal but distinct role for both PfSir2 paralogues in epigenetic silencing of P. falciparum virulence genes and the control of pathogenicity of malaria infection.

  18. Putative DNA G-quadruplex formation within the promoters of Plasmodium falciparum var genes

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    Rowe J

    2009-08-01

    Full Text Available Abstract Background Guanine-rich nucleic acid sequences are capable of folding into an intramolecular four-stranded structure called a G-quadruplex. When found in gene promoter regions, G-quadruplexes can downregulate gene expression, possibly by blocking the transcriptional machinery. Here we have used a genome-wide bioinformatic approach to identify Putative G-Quadruplex Sequences (PQS in the Plasmodium falciparum genome, along with biophysical techniques to examine the physiological stability of P. falciparum PQS in vitro. Results We identified 63 PQS in the non-telomeric regions of the P. falciparum clone 3D7. Interestingly, 16 of these PQS occurred in the upstream region of a subset of the P. falciparum var genes (group B var genes. The var gene family encodes PfEMP1, the parasite's major variant antigen and adhesin expressed at the surface of infected erythrocytes, that plays a key role in malaria pathogenesis and immune evasion. The ability of the PQS found in the upstream regions of group B var genes (UpsB-Q to form stable G-quadruplex structures in vitro was confirmed using 1H NMR, circular dichroism, UV spectroscopy, and thermal denaturation experiments. Moreover, the synthetic compound BOQ1 that shows a higher affinity for DNA forming quadruplex rather than duplex structures was found to bind with high affinity to the UpsB-Q. Conclusion This is the first demonstration of non-telomeric PQS in the genome of P. falciparum that form stable G-quadruplexes under physiological conditions in vitro. These results allow the generation of a novel hypothesis that the G-quadruplex sequences in the upstream regions of var genes have the potential to play a role in the transcriptional control of this major virulence-associated multi-gene family.

  19. Plasmodium falciparum exhibits markers of regulated cell death at high population density in vitro.

    Science.gov (United States)

    Engelbrecht, Dewaldt; Coetzer, Thérèsa Louise

    2016-12-01

    The asexual erythrocytic cycle of the protozoan parasite Plasmodium falciparum is responsible for the pathogenesis of malaria and causes the overwhelming majority of malaria deaths. Rapidly increasing parasitaemia during this 48hour cycle threatens the survival of the human host and the parasite prior to transmission of the slow-maturing sexual stages to the mosquito host. The parasite may utilise regulated cell death (RCD) to control the burden of infection on the host and thus aid its own survival and transmission. The occurrence of RCD in P. falciparum remains a controversial topic. We provide strong evidence for the occurrence of an apoptosis-like phenotype of RCD in P. falciparum under conditions of high parasite density. P. falciparum was maintained in vitro and stressed by allowing growth to an unrestricted peak parasitaemia. Cell death markers, including morphological changes, DNA fragmentation, mitochondrial polarisation and phosphatidylserine externalisation were used to characterise parasite death at the time of peak parasitaemia and 24h later. At peak parasitaemia, mitochondrial depolarisation was observed, together with phosphatidylserine externalisation in both parasitised- and neighbouring non-infected erythrocytes. DNA fragmentation coincided with a decline in parasitaemia. Fewer merozoites were observed in mature schizonts at peak parasitaemia. Growth recovery to near-peak parasitaemia was noted within two intraerythrocytic cycles. The combination and chronological order of the biochemical markers of cell death suggest the occurrence of an apoptosis-like phenotype. The identification of a RCD pathway in P. falciparum may provide novel drug targets, particularly if the pathway differs from the host machinery. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

  20. Sunlight inhibits growth and induces markers of programmed cell death in Plasmodium falciparum in vitro.

    Science.gov (United States)

    Engelbrecht, Dewaldt; Coetzer, Thérèsa Louise

    2015-09-29

    Plasmodium falciparum is responsible for the majority of global malaria deaths. During the pathogenic blood stages of infection, a rapid increase in parasitaemia threatens the survival of the host before transmission of slow-maturing sexual parasites to the mosquito vector to continue the life cycle. Programmed cell death (PCD) may provide the parasite with the means to control its burden on the host and thereby ensure its own survival. Various environmental stress factors encountered during malaria may induce PCD in P. falciparum. This study is the first to characterize parasite cell death in response to natural sunlight. The 3D7 strain of P. falciparum was cultured in vitro in donor erythrocytes. Synchronized and mixed-stage parasitized cultures were exposed to sunlight for 1 h and compared to cultures maintained in the dark, 24 h later. Mixed-stage parasites were also subjected to a second one-hour exposure at 24 h and assessed at 48 h. Parasitaemia was measured daily by flow cytometry. Biochemical markers of cell death were assessed, including DNA fragmentation, mitochondrial membrane polarization and phosphatidylserine externalization. Sunlight inhibited P. falciparum growth in vitro. Late-stage parasites were more severely affected than early stages. However, some late-stage parasites survived exposure to sunlight to form new rings 24 h later, as would be expected during PCD whereby only a portion of the population dies. DNA fragmentation was observed at 24 and 48 h and preceded mitochondrial hyperpolarization in mixed-stage parasites at 48 h. Mitochondrial hyperpolarization likely resulted from increased oxidative stress. Although data suggested increased phosphatidylserine externalization in mixed-stage parasites, results were not statistically significant. The combination of biochemical markers and the survival of some parasites, despite exposure to a lethal stimulus, support the occurrence of PCD in P. falciparum.

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

    Directory of Open Access Journals (Sweden)

    Odilon Nouatin

    Full Text Available 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.

  2. The Pf332 gene codes for a megadalton protein of Plasmodium falciparum asexual blood stages

    Directory of Open Access Journals (Sweden)

    Denise Mattei

    1992-01-01

    Full Text Available We characterized the Plasmodium falciparum antigen 332 (Ag332 which is specifically expressed during the asexual intraerythrocytic cycle of the parasite. The corresponding Pf332 gene has been located in the subtelomeric region of chromosome 11. Furthermore, it is present in all strais so far analyzed and shows marked restriction length fragment polymorphism. Partial sequence and restriction endonuclease digestion of cloned fragments revealed that the Pf332 gene is composed of highly degenerated repeats rich is glutamic acid. Mung been nuclease digestion and Northern blot analysis suggested that Pf332 gene codes for a protein of about 700 kDa. These data were further confirmed by Western blot and immunoprecipitation of parasites extracts with an antiserum raised against a recombinant clone expressing part of the Ag332. Confocal immunofluorescence showed that Ag332 is translocated from the parasite to the surface of infected red blood cells within vesicle-like structures. In addition, Ag332 was detected on the surface of monkey erythrocytes infected with Plasmodium falciparum.

  3. Immunomagnetic capture and colorimetric detection of malarial biomarker Plasmodium falciparum lactate dehydrogenase.

    Science.gov (United States)

    Markwalter, Christine F; Davis, Keersten M; Wright, David W

    2016-01-15

    We report a sensitive, magnetic bead-based colorimetric assay for Plasmodium falciparum lactate dehydrogenase (PfLDH) in which the biomarker is extracted from parasitized whole blood and purified based on antigen binding to antibody-functionalized magnetic particles. Antigen-bound particles are washed, and PfLDH activity is measured on-bead using an optimized colorimetric enzyme reaction (limit of detection [LOD] = 21.1 ± 0.4 parasites/μl). Enhanced analytical sensitivity is achieved by removal of PfLDH from the sample matrix before detection and elimination of nonspecific reductases and species that interfere with the optimal detection wavelength for measuring assay development. The optimized assay represents a simple and effective diagnostic strategy for P. falciparum malaria with time-to-result of 45 min and detection limits similar to those of commercial enzyme-linked immunosorbent assay (ELISA) kits, which can take 4-6 h. This method could be expanded to detect all species of malaria by switching the capture antibody on the magnetic particles to a pan-specific Plasmodium LDH antibody. Copyright © 2015 The Authors. Published by Elsevier Inc. All rights reserved.

  4. Design, synthesis, and biological evaluation of Plasmodium falciparum lactate dehydrogenase inhibitors.

    Science.gov (United States)

    Choi, Seoung-ryoung; Pradhan, Anupam; Hammond, Nicholas L; Chittiboyina, Amar G; Tekwani, Babu L; Avery, Mitchell A

    2007-08-09

    Plasmodium falciparum lactate dehydrogenase (pfLDH) is a key enzyme for energy generation of malarial parasites and is a potential antimalarial chemotherapeutic target. It is known that the oxamate moiety, a pyruvate analog, alone shows higher inhibition against pfLDH than human LDHs, suggesting that it can be used for the development of selective inhibitors. Oxamic acid derivatives were designed and synthesized. Derivatives 5 and 7 demonstrated activities against pfLDH with IC50 values of 3.13 and 1.75 muM, respectively, and have 59- and 7-fold selectivity over mammalian LDH, respectively. They also have micromolar range activities against Plasmodium falciparum malate dehydrogenase (pfMDH), which may fill the role of pfLDH when the activity of pfLDH is reduced. Thus, certain members of these oxamic acid derivatives may have dual inhibitory activities against both pfLDH and pfMDH. It is presumed that dual LDH/MDH inhibitors would have enhanced potential as antimalarial drugs.

  5. Malária por Plasmodium falciparum: estudos proteômicos

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    Rodrigo Siqueira-Batista

    2012-12-01

    Full Text Available A despeito dos avanços no tratamento e das campanhas de prevenção e de controle da malária nos distintos continentes nos quais a moléstia grassa, a entidade mórbida permanece com significativa relevância no mundo contemporâneo. O Plasmodium falciparum é o grande responsável pela malária grave, caracterizada por distúrbios em diferentes órgãos e sistemas, com possibilidade de evolução ao óbito. Embora incipientes, os estudos proteômicos na malária têm trazido boas perspectivas para melhor compreensão dos aspectos biológicos do Plasmodium, assim como dos mecanismos fisiopatológicos, diagnósticos, terapêuticos e profiláticos da enfermidade. Desse modo, o objetivo do presente artigo é apresentar uma breve revisão das aplicações da análise proteômica na malária por P. falciparum.

  6. Caracterización parcial de la calmodulina de Plasmodium falciparum

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    Claudia P. Tinjacá

    1995-12-01

    Full Text Available Se describe una alternativa para la purificación parcial de Calmodulina (CaM a partir de Plasmodium falciparum que, de acuerdo con anticuerpos monoclonales altamente especificas contra CaM, permite separar por lo menos dos formas de la proteína que, aunque difieren en sus pesos moleculares (una pequeña de 12.600 y otra grande entre 36.000 y 50.000 daltones, son capaces de estimular a la ATPasa de calcio del eritrocito por separado. Se plantea la posibilidad de una modificación estructural de la CaM dePlasmodium falciparum, que no interfiere con su función como activadora de la ATPasa de calcio y que la hace inhibible en menor grado que la CaM de eritrocito en su función estimuladora de la enzima. Lo anterior hace pensar en una mayor afinidad de la proteína del parásito por esta enzima o en una modificación de la zona regulatoria a la que se unen los inhibidores.

  7. Artemether–lumefantrine in the treatment of uncomplicated Plasmodium falciparum malaria

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    Stephan Ehrhardt

    2009-10-01

    Full Text Available Stephan Ehrhardt, Christian G MeyerBernhard Nocht Institute for Tropical Medicine, Tropical Medicine Section, Hamburg, GermanyAbstract: The World Health Organization strongly recommends artemisinin-based combination therapy (ACT regimens for the treatment of uncomplicated Plasmodium falciparum malaria cases in endemic areas. Among the combinations of compounds that are available at present, excellent results have been obtained for the artemisinin derivative artemether, in a combination galenic preparation with lumefantrine (artemether–lumefantrine, AL. Here, the pharmacological properties and the therapeutic options of both substances are briefly reviewed and a cursory overview is given on recent trials that have compared the therapeutic effects of AL in the standard 6-dose regimen with other antimalarials and combinations. In order to ensure the most achievable and reliable adherence and compliance of children in the treatment of malaria, a dispersible formulation of AL is now attainable. Recent reports on the emergence of resistance to ACT regimens in Asia, however, are alarming.Keywords: artemether, lumefantrine, malaria, Plasmodium falciparum, dispersible formulation, treatment, therapy

  8. A chemical rescue screen identifies a Plasmodium falciparum apicoplast inhibitor targeting MEP isoprenoid precursor biosynthesis.

    Science.gov (United States)

    Wu, Wesley; Herrera, Zachary; Ebert, Danny; Baska, Katie; Cho, Seok H; DeRisi, Joseph L; Yeh, Ellen

    2015-01-01

    The apicoplast is an essential plastid organelle found in Plasmodium parasites which contains several clinically validated antimalarial-drug targets. A chemical rescue screen identified MMV-08138 from the "Malaria Box" library of growth-inhibitory antimalarial compounds as having specific activity against the apicoplast. MMV-08138 inhibition of blood-stage Plasmodium falciparum growth is stereospecific and potent, with the most active diastereomer demonstrating a 50% effective concentration (EC50) of 110 nM. Whole-genome sequencing of 3 drug-resistant parasite populations from two independent selections revealed E688Q and L244I mutations in P. falciparum IspD, an enzyme in the MEP (methyl-d-erythritol-4-phosphate) isoprenoid precursor biosynthesis pathway in the apicoplast. The active diastereomer of MMV-08138 directly inhibited PfIspD activity in vitro with a 50% inhibitory concentration (IC50) of 7.0 nM. MMV-08138 is the first PfIspD inhibitor to be identified and, together with heterologously expressed PfIspD, provides the foundation for further development of this promising antimalarial drug candidate lead. Furthermore, this report validates the use of the apicoplast chemical rescue screen coupled with target elucidation as a discovery tool to identify specific apicoplast-targeting compounds with new mechanisms of action. Copyright © 2015, American Society for Microbiology. All Rights Reserved.

  9. A semi-synthetic glycosaminoglycan analogue inhibits and reverses Plasmodium falciparum cytoadherence.

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    Mark A Skidmore

    Full Text Available A feature of mature Plasmodium falciparum parasitized red blood cells is their ability to bind surface molecules of the microvascular endothelium via the parasite-derived surface protein Plasmodium falciparum erythrocyte membrane protein 1 (PfEMP1. This ligand is associated with the cytoadherence pathology observed in severe malaria. As pRBC treated with effective anti-malarial drugs are still able to cytoadhere, there is therefore a need to find an adjunct treatment that can inhibit and reverse the adhesion process. One semi-synthetic, sulfated polysaccharide has been identified that is capable of inhibiting and reversing sequestration of pRBC on endothelial cells in vitro under physiological flow conditions. Furthermore, it exhibits low toxicity in the intrinsic (APTT assay and extrinsic (PT assay clotting pathways, as well as exhibiting minimal effects on cell (HUVEC viability (MTT proliferation assay. These findings suggest that carbohydrate-based anti-adhesive candidates may provide potential leads for therapeutics for severe malaria.

  10. DNA Sequence Polymorphism of the Lactate Dehydrogenase Genefrom Iranian Plasmodium vivax and Plasmodium falciparum Isolates

    OpenAIRE

    GETACHER FELEKE, Daniel; NATEGHPOUR, Mehdi; MOTEVALLI HAGHI, Afsaneh; HAJJARAN, Homa; FARIVAR, Leila; MOHEBALI, Mehdi; RAOOFIAN, Reza

    2015-01-01

    Background: Parasite lactate dehydrogenase (pLDH) is extensively employed as malaria rapid diagnostic tests (RDTs). Moreover, it is a well-known drug target candidate. However, the genetic diversity of this gene might influence performance of RDT kits and its drug target candidacy. This study aimed to determine polymorphism of pLDH gene from Iranian isolates of P. vivax and P. falciparum. Methods: Genomic DNA was extracted from whole blood of microscopically confirmed P. vivax and P. falcipar...

  11. A case-control auditory evaluation of patients treated with artemisinin derivatives for multidrug-resistant Plasmodium falciparum malaria

    NARCIS (Netherlands)

    van Vugt, M.; Angus, B. J.; Price, R. N.; Mann, C.; Simpson, J. A.; Poletto, C.; Htoo, S. E.; Looareesuwan, S.; White, N. J.; Nosten, F.

    2000-01-01

    The artemisinin derivatives are now used widely in areas with multidrug-resistant Plasmodium falciparum malaria such as Southeast Asia, but concerns remain over their potential for neurotoxicity. Mice, rats, dogs, and monkeys treated with high doses of intramuscular artemether or arteether develop

  12. Differential induction of functional IgG using the Plasmodium falciparum placental malaria vaccine candidate VAR2CSA

    DEFF Research Database (Denmark)

    Pinto, Vera V; Ditlev, Sisse B; Jensen, Kamilla E

    2011-01-01

    In Plasmodium falciparum malaria endemic areas placental malaria (PM) is an important complication of malaria. The recurrence of malaria in primigravidae women irrespective of acquired protection during childhood is caused by the interaction between the parasite-expressed VAR2CSA antigen...

  13. Global histone analysis by mass spectrometry reveals a high content of acetylated lysine residues in the malaria parasite Plasmodium falciparum

    DEFF Research Database (Denmark)

    Trelle, Morten Beck; Salcedo-Amaya, Adriana M; Cohen, Adrian

    2009-01-01

    Post-translational modifications (PTMs) of histone tails play a key role in epigenetic regulation of gene expression in a range of organisms from yeast to human, however, little is known about histone proteins from the parasite that causes malaria in humans, Plasmodium falciparum. We characterized...

  14. Plasmodium falciparum: VAR2CSA expressed during pregnancy-associated malaria is partially resistant to proteolytic cleavage by trypsin

    DEFF Research Database (Denmark)

    Nielsen, Morten A; Resende, Mafalda; Alifrangis, Michael

    2007-01-01

    In areas of high Plasmodium falciparum transmission, immunity to malaria is acquired during childhood, so that adults in general are clinically immune. One exception is that first-time pregnant women are susceptible to pregnancy-associated malaria caused by accumulation of parasites in the placenta...... mediates the adhesive and antigenic phenotypes shown by parasites causing placental malaria....

  15. Persistent Epstein-Barr viral reactivation in young African children with a history of severe Plasmodium falciparum malaria.

    NARCIS (Netherlands)

    Yone, C.L.; Kube, D.; Kremsner, P.G.; Luty, A.J.F.

    2006-01-01

    Epstein-Barr virus (EBV) and Plasmodium falciparum have overlapping distributions and are thought to have causal interactions, particularly with regard to the aetiology of endemic Burkitt's lymphoma. Using real-time PCR, we quantified and compared EBV DNA levels in the blood before and after

  16. Morbidity from malaria and immune responses to defined Plasmodium falciparum antigens in children with sickle cell trait in The Gambia

    DEFF Research Database (Denmark)

    Allen, S J; Bennett, S; Riley, E M

    1993-01-01

    Morbidity from Plasmodium falciparum malaria and humoral and in vitro cellular immune responses to defined malaria antigens were measured in rural Gambian children with haemoglobin phenotype AS (HbAS) and in those with a normal haemoglobin (HbAA). In a survey undertaken during the dry season, HbA...

  17. Detection of Single-Nucleotide Polymorphisms in Plasmodium falciparum by PCR Primer Extension and Lateral Flow Immunoassay

    NARCIS (Netherlands)

    Moers, A.P.H.A.; Hallett, R.L.; Borrow, R.; Schallig, H.D.F.H.; Sutherland, C.J.; Amerongen, van A.

    2015-01-01

    The resistance of Plasmodium falciparum to some antimalarial drugs is linked to single-nucleotide polymorphisms (SNPs). Currently, there are no methods for the identification of resistant parasites that are sufficiently simple, cheap, and fast enough to be performed at point-of-care, i.e., in local

  18. Therapeutic Efficacy of Artemether-Lumefantrine for the Treatment of Uncomplicated Plasmodium falciparum Malaria in Northern Ethiopia

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    Gebremedhin Kinfu

    2012-01-01

    Full Text Available Introduction. Multidrug resistance of Plasmodium falciparum is spreading throughout Africa. This has posed major challenges to malaria control in sub-Saharan Africa. Objective. The aim of the study was to evaluate the efficacy of artemether-lumefantrine for the treatment of uncomplicated Plasmodium falciparum malaria in North Ethiopia. Methods. This prospective study was undertaken during August–November 2009 on 71 malaria patients that fulfilled the inclusion criteria set by the WHO. Patients were followed up for 28 days. Thick and thin blood films were prepared by Giemsa stain for microscopy to determine parasite density. A standard six-dose regimen of artemether-lumefantrine was administered over three days and was followed up with clinical and parasitological evaluations over 28 days. Results. The cure rate (ACPR was found to be high (97.2% in this study. The parasite and fever clearance time was also rapid. Artemether-lumefantrine for the treatment of acute uncomplicated Plasmodium falciparum malaria in the study area showed 97.2% cure rate and only 2.8% failure rate. Conclusion. The result showed that the drug could continue as first line for the treatment of uncomplicated Plasmodium falciparum malaria in the study area. The efficacy of artemether-lumefantrine needs to be carefully monitored periodically in sentinel sites representing different areas of the country.

  19. Assessment of the molecular marker of Plasmodium falciparum chloroquine resistance (Pfcrt) in Senegal after several years of chloroquine withdrawal

    DEFF Research Database (Denmark)

    Ndiaye, Magatte; Faye, Babacar; Tine, Roger

    2012-01-01

    at the molecular level in selected sites in Senegal, because the scientific community is interested in using CQ again. Finger prick blood samples were collected from Plasmodium falciparum-positive children below the age of 10 years (N = 474) during cross-sectional surveys conducted in two study sites in Senegal...

  20. Plasmodium falciparum parasites expressing pregnancy-specific variant surface antigens adhere strongly to the choriocarcinoma cell line BeWo

    DEFF Research Database (Denmark)

    Haase, Rikke N; Megnekou, Rosette; Lundquist, Maja

    2006-01-01

    Placenta-sequestering Plasmodium falciparum parasites causing pregnancy-associated malaria express pregnancy-specific variant surface antigens (VSA(PAM)). We report here that VSA(PAM)-expressing patient isolates adhere strongly to the choriocarcinoma cell line BeWo and that the BeWo line can...

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

    DEFF Research Database (Denmark)

    Hempel, Casper; Boisen, Ida M; Efunshile, Akinwale

    2015-01-01

    BACKGROUND: Plasmodium falciparum exports antigens to the surface of infected erythrocytes causing cytoadhesion to the host vasculature. This is central in malaria pathogenesis but in vitro studies of cytoadhesion rely mainly on manual counting methods. The current study aimed at developing...

  2. Estimated risk of placental infection and low birthweight attributable to Plasmodium falciparum malaria in Africa in 2010: a modelling study

    NARCIS (Netherlands)

    Walker, Patrick G. T.; ter Kuile, Feiko O.; Garske, Tini; Menendez, Clara; Ghani, Azra C.

    2014-01-01

    Plasmodium falciparum infection during pregnancy leads to adverse outcomes including low birthweight; however, contemporary estimates of the potential burden of malaria in pregnancy in Africa (in the absence of interventions) are poor. We aimed to estimate the need to protect pregnant women from

  3. Differential induction of immunoglobulin G to Plasmodium falciparum variant surface antigens during the transmission season in Daraweesh, Sudan

    DEFF Research Database (Denmark)

    Nielsen, Morten A; Grevstad, Berit; A-Elgadir, Thoraya M E

    2005-01-01

    with severe malaria (VSA(SM)) are frequently recognized by IgG. METHODS: We analyzed levels of anti-VSA IgG in 57 individuals in Daraweesh, Sudan, before and after the transmission season. IgG responses to 79 Plasmodium falciparum isolates from children with defined malaria syndromes and exposed to high...

  4. Reduced prevalence of Plasmodium falciparum infection and of concomitant anaemia in pregnant women with heterozygous G6PD deficiency

    NARCIS (Netherlands)

    Mockenhaupt, Frank P.; Mandelkow, Jantina; Till, Holger; Ehrhardt, Stephan; Eggelte, Teunis A.; Bienzle, Ulrich

    2003-01-01

    Glucose-6-phosphate dehydrogenase (G6PD) deficiency confers protection against malaria in children, yet its role in malaria in pregnancy is unknown. In a cross-sectional study among 529 pregnant Ghanaian women, Plasmodium falciparum infection, anaemia and G6PD genotypes were assessed. Of these,

  5. Genetic variation in the Plasmodium falciparum circumsporozoite protein in India and its relevance to RTS,S malaria vaccine

    NARCIS (Netherlands)

    Zeeshan, M.; Alam, M.T.; Vinayak, S.; Bora, H.; Tyagi, R.K.; Alam, M.S.; Choudhary, V.; Mittra, P.; Lumb, V.; Bharti, P.K.; Udhayakumar, V.; Singh, N.; Jain, V.; Singh, P.P.; Sharma, Y.D.

    2012-01-01

    RTS,S is the most advanced malaria vaccine candidate, currently under phase-III clinical trials in Africa. This Plasmodium falciparum vaccine contains part of the central repeat region and the complete C-terminal T cell epitope region (Th2R and Th3R) of the circumsporozoite protein (CSP). Since

  6. The sickle cell trait is associated with enhanced immunoglobulin G antibody responses to Plasmodium falciparum variant surface antigens.

    NARCIS (Netherlands)

    Cabrera, G.; Cot, M.; Migot-Nabias, F.; Kremsner, P.G.; Deloron, P.; Luty, A.J.F.

    2005-01-01

    The sickle cell trait (HbAS) protects against severe Plasmodium falciparum malaria in young African children. We investigated the extent of the association between HbAS and antibodies directed to parasite-derived variant surface antigens (VSAs) on the membrane of infected erythrocytes. We measured

  7. Structure and Function of Plasmodium falciparum malate dehydrogenase: Role of Critical Amino Acids in C-substrate Binding Procket

    Science.gov (United States)

    Malaria parasite thrives on anaerobic fermentation of glucose for energy. Earlier studies from our lab have demonstrated that a cytosolic malate dehydrogenase (PfMDH) with striking similarity to lactate dehydrogenase (PfLDH) might complement PfLDH function in Plasmodium falciparum. The N-terminal g...

  8. Plasmodium falciparum Expressing Domain Cassette 5 Type PfEMP1 (DC5-PfEMP1) Bind PECAM1

    DEFF Research Database (Denmark)

    Berger, Sanne S; Turner, Louise; Wang, Christian W

    2013-01-01

    Members of the Plasmodium falciparum Erythrocyte Membrane protein 1 (PfEMP1) family expressed on the surface of malaria-infected erythrocytes mediate binding of the parasite to different receptors on the vascular lining. This process drives pathologies, and severe childhood malaria has been...

  9. Analysis of Quaternary Structure of a [LDH-like] Malate Dehydrogenase of Plasmodium falciparum with Oligomeric Mutants

    Science.gov (United States)

    L-Malate dehydrogenase (PfMDH) from Plasmodium falciparum, the causative agent for the most severe form of malaria, has shown remarkable similarities to L-lactate dehydrogenase (PfLDH). PfMDH is more closely related to [LDH-like] MDHs characterized in archea and other prokaryotes. Initial sequence a...

  10. Hierarchical, domain type-specific acquisition of antibodies to Plasmodium falciparum erythrocyte membrane protein 1 in Tanzanian children

    DEFF Research Database (Denmark)

    Cham, Gerald K K; Turner, Louise; Kurtis, Jonathan D

    2010-01-01

    Plasmodium falciparum erythrocyte membrane protein 1 (PfEMP1) is a variant antigen expressed on the surface of malaria-infected erythrocytes. PfEMP1 attaches to the vascular lining and allows infected erythrocytes to avoid filtration through the spleen. Each parasite genome encodes about 60...

  11. Expression of the domain cassette 8 Plasmodium falciparum erythrocyte membrane protein 1 is associated with cerebral malaria in Benin

    DEFF Research Database (Denmark)

    Bertin, Gwladys I; Lavstsen, Thomas; Guillonneau, François

    2013-01-01

    Plasmodium falciparum erythrocyte membrane protein-1 (PfEMP-1) is a highly polymorphic adherence receptor expressed on the surface of infected erythrocytes. Based on sequence homology PfEMP-1 variants have been grouped into three major groups A-C, the highly conserved VAR2CSA variants, and semi...

  12. In vivo sensitivity of Plasmodium falciparum to chloroquine in rural areas of Côte d'Ivoire

    NARCIS (Netherlands)

    Henry, M. C.; Docters van Leeuwen, W.; Watson, P.; Jansen, A.; Jacobs, K.; Zwart, F.; Agricola, K.; Nahounou, N.; Dossou, J.; Eggelte, T. E.

    1994-01-01

    In vivo testing of Plasmodium falciparum sensitivity to chloroquine was carried out in four rural sites of differing socio-geographical environment in Côte d'Ivoire. Of a total of 1282 patients of all ages with fever or previous history of fever, 649 were slide positive, with 435 patients with a

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

    Science.gov (United States)

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

    2012-05-01

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

  14. Harnessing evolutionary fitness in Plasmodium falciparum for drug discovery and suppressing resistance.

    Science.gov (United States)

    Lukens, Amanda K; Ross, Leila Saxby; Heidebrecht, Richard; Javier Gamo, Francisco; Lafuente-Monasterio, Maria J; Booker, Michael L; Hartl, Daniel L; Wiegand, Roger C; Wirth, Dyann F

    2014-01-14

    Drug resistance emerges in an ecological context where fitness costs restrict the diversity of escape pathways. These pathways are targets for drug discovery, and here we demonstrate that we can identify small-molecule inhibitors that differentially target resistant parasites. Combining wild-type and mutant-type inhibitors may prevent the emergence of competitively viable resistance. We tested this hypothesis with a clinically derived chloroquine-resistant (CQ(r)) malaria parasite and with parasites derived by in vitro selection with Plasmodium falciparum dihydroorotate dehydrogenase (PfDHODH) inhibitors. We screened a chemical library against CQ(s) and CQ(r) lines and discovered a drug-like compound (IDI-3783) that was potent only in the CQ(r) line. Surprisingly, in vitro selection of Plasmodium falciparum resistant to IDI-3783 restored CQ sensitivity, thereby indicating that CQ might once again be useful as a malaria therapy. In parallel experiments, we selected P. falciparum lines resistant to structurally unrelated PfDHODH inhibitors (Genz-666136 and DSM74). Both selections yielded resistant lines with the same point mutation in PfDHODH:E182D. We discovered a compound (IDI-6273) more potent against E182D than wild-type parasites. Selection of the E182D mutant with IDI-6273 yielded a reversion to the wild-type protein sequence and phenotype although the nucleotide sequence was different. Importantly, selection with a combination of Genz-669178, a wild-type PfDHODH inhibitor, and IDI-6273, a mutant-selective PfDHODH inhibitor, did not yield resistant parasites. These two examples demonstrate that the compromise between resistance and evolutionary fitness can be exploited to design therapies that prevent the emergence and spread of resistant organisms.

  15. A high parasite density environment induces transcriptional changes and cell death in Plasmodium falciparum blood stages.

    Science.gov (United States)

    Chou, Evelyn S; Abidi, Sabia Z; Teye, Marian; Leliwa-Sytek, Aleksandra; Rask, Thomas S; Cobbold, Simon A; Tonkin-Hill, Gerry Q; Subramaniam, Krishanthi S; Sexton, Anna E; Creek, Darren J; Daily, Johanna P; Duffy, Michael F; Day, Karen P

    2017-12-27

    Transient regulation of Plasmodium numbers below the density that induces fever has been observed in chronic malaria infections in humans. This species transcending control cannot be explained by immunity alone. Using an in vitro system we have observed density dependent regulation of malaria population size as a mechanism to possibly explain these in vivo observations. Specifically, Plasmodium falciparum blood stages from a high but not low-density environment exhibited unique phenotypic changes during the late trophozoite (LT) and schizont stages of the intraerythrocytic cycle. These included in order of appearance: failure of schizonts to mature and merozoites to replicate, apoptotic-like morphological changes including shrinking, loss of mitochondrial membrane potential, and blebbing with eventual release of aberrant parasites from infected erythrocytes. This unique death phenotype was triggered in a stage-specific manner by sensing of a high-density culture environment. Conditions of glucose starvation, nutrient depletion, and high lactate could not induce the phenotype. A high-density culture environment induced rapid global changes in the parasite transcriptome including differential expression of genes involved in cell remodeling, clonal antigenic variation, metabolism, and cell death pathways including an apoptosis-associated metacaspase gene. This transcriptional profile was also characterized by concomitant expression of asexual and sexual stage-specific genes. The data show strong evidence to support our hypothesis that density sensing exists in P. falciparum. They indicate that an apoptotic-like mechanism may play a role in P. falciparum density regulation, which, as in yeast, has features quite distinguishable from mammalian apoptosis. Gene expression data are available in the GEO databases under the accession number GSE91188. © 2017 Federation of European Biochemical Societies.

  16. FCRL5 Delineates Functionally Impaired Memory B Cells Associated with Plasmodium falciparum Exposure.

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    Richard T Sullivan

    2015-05-01

    Full Text Available Exposure to Plasmodium falciparum is associated with circulating "atypical" memory B cells (atMBCs, which appear similar to dysfunctional B cells found in HIV-infected individuals. Functional analysis of atMBCs has been limited, with one report suggesting these cells are not dysfunctional but produce protective antibodies. To better understand the function of malaria-associated atMBCs, we performed global transcriptome analysis of these cells, obtained from individuals living in an area of high malaria endemicity in Uganda. Comparison of gene expression data suggested down-modulation of B cell receptor signaling and apoptosis in atMBCs compared to classical MBCs. Additionally, in contrast to previous reports, we found upregulation of Fc receptor-like 5 (FCRL5, but not FCRL4, on atMBCs. Atypical MBCs were poor spontaneous producers of antibody ex vivo, and higher surface expression of FCRL5 defined a distinct subset of atMBCs compromised in its ability to produce antibody upon stimulation. Moreover, higher levels of P. falciparum exposure were associated with increased frequencies of FCRL5+ atMBCs. Together, our findings suggest that FCLR5+ identifies a functionally distinct, and perhaps dysfunctional, subset of MBCs in individuals exposed to P. falciparum.

  17. Extracts from Annona Muricata L. and Annona Reticulata L. (Annonaceae) Potently and Selectively Inhibit Plasmodium Falciparum

    Science.gov (United States)

    Yamthe, Lauve Rachel Tchokouaha; Fokou, Patrick Valere Tsouh; Mbouna, Cedric Derick Jiatsa; Keumoe, Rodrigue; Ndjakou, Bruno Lenta; Djouonzo, Paul Toukam; Mfopa, Alvine Ngoutane; Legac, Jennifer; Tsabang, Nole; Gut, Jiri; Rosenthal, Philip J.; Boyom, Fabrice Fekam

    2015-01-01

    The aim of this work was to screen extracts from Annona muricata and Annona reticulata in vitro against Plasmodium falciparum. Crude ethanolic extracts, methylene chloride fractions, aqueous fractions, subfractions and isolated compounds (stigmasterol-3-O-β-d-glucopyranoside, lichexanthone, gallic acid and β-sitosterol-3-O-β-d-glucopyranoside) were tested for cytotoxicity on erythrocytes and Human Foreskin Fibroblasts cells and against the W2 strain of P. falciparum in culture. Results indicated that none of the extracts was cytotoxic at concentrations up to 10 µg/mL. Most of the extracts, fractions and subfractions inhibited the growth of P. falciparum with IC50 values ranging from 0.07 to 3.46 µg/mL. The most potent was the subfraction 30 from A. muricata stem bark (IC50 = 0.07 µg/mL) with a selectivity index of ˃ 142. Subfraction 3 from A. muricata root also exhibited very good activity (IC50 = 0.09 µg/mL) with a high selectivity index (SI ˃ 111). Amongst the isolated compounds, only gallic acid showed activity with IC50 of 3.32 µg/mL and SI > 10. These results support traditional claims for A. muricata and A. reticulata in the treatment of malaria. Given their limited cytotoxicity profile, their extracts qualify as promising starting points for antimalarial drug discovery. PMID:28930201

  18. Independent emergence of artemisinin resistance mutations among Plasmodium falciparum in Southeast Asia.

    Science.gov (United States)

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

    2015-03-01

    The emergence of artemisinin-resistant Plasmodium falciparum in Southeast Asia threatens malaria treatment efficacy. Mutations in a kelch protein encoded on P. falciparum chromosome 13 (K13) have been associated with resistance in vitro and in field samples from Cambodia. P. falciparum infections from artesunate efficacy trials in Bangladesh, Cambodia, Laos, Myanmar, and Vietnam were genotyped at 33 716 genome-wide single-nucleotide polymorphisms (SNPs). Linear mixed models were used to test associations between parasite genotypes and parasite clearance half-lives following artesunate treatment. K13 mutations were tested for association with artemisinin resistance, and extended haplotypes on chromosome 13 were examined to determine whether mutations arose focally and spread or whether they emerged independently. The presence of nonreference K13 alleles was associated with prolonged parasite clearance half-life (P = 1.97 × 10(-12)). Parasites with a mutation in any of the K13 kelch domains displayed longer parasite clearance half-lives than parasites with wild-type alleles. Haplotype analysis revealed both population-specific emergence of mutations and independent emergence of the same mutation in different geographic areas. K13 appears to be a major determinant of artemisinin resistance throughout Southeast Asia. While we found some evidence of spreading resistance, there was no evidence of resistance moving westward from Cambodia into Myanmar. © The Author 2014. Published by Oxford University Press on behalf of the Infectious Diseases Society of America. All rights reserved. For Permissions, please e-mail: journals.permissions@oup.com.

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

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    Sangare Ibrahim

    2013-01-01

    Full Text Available Abstract 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.

  20. Plasmodium falciparum malaria importation from Africa to China and its mortality: an analysis of driving factors

    Science.gov (United States)

    Lai, Shengjie; Wardrop, Nicola A.; Huang, Zhuojie; Bosco, Claudio; Sun, Junling; Bird, Tomas; Wesolowski, Amy; Zhou, Sheng; Zhang, Qian; Zheng, Canjun; Li, Zhongjie; Tatem, Andrew J.; Yu, Hongjie

    2016-12-01

    Plasmodium falciparum malaria importation from Africa to China is rising with increasing Chinese overseas investment and international travel. Identifying networks and drivers of this phenomenon as well as the contributors to high case-fatality rate is a growing public health concern to enable efficient response. From 2011-2015, 8653 P. falciparum cases leading to 98 deaths (11.3 per 1000 cases) were imported from 41 sub-Saharan countries into China, with most cases (91.3%) occurring in labour-related Chinese travellers. Four strongly connected groupings of origin African countries with destination Chinese provinces were identified, and the number of imported cases was significantly associated with the volume of air passengers to China (P = 0.006), parasite prevalence in Africa (P malaria diagnosis and diverse socioeconomic factors. The spatial heterogeneity uncovered, principal drivers explored, and risk factors for mortality found in the rising rates of P. falciparum malaria importation to China can serve to refine malaria elimination strategies and the management of cases, and high risk groups and regions should be targeted.

  1. Novel inhibitors of Plasmodium falciparum dihydroorotate dehydrogenase with anti-malarial activity in the mouse model.

    Science.gov (United States)

    Booker, Michael L; Bastos, Cecilia M; Kramer, Martin L; Barker, Robert H; Skerlj, Renato; Sidhu, Amar Bir; Deng, Xiaoyi; Celatka, Cassandra; Cortese, Joseph F; Guerrero Bravo, Jose E; Crespo Llado, Keila N; Serrano, Adelfa E; Angulo-Barturen, Iñigo; Jiménez-Díaz, María Belén; Viera, Sara; Garuti, Helen; Wittlin, Sergio; Papastogiannidis, Petros; Lin, Jing-Wen; Janse, Chris J; Khan, Shahid M; Duraisingh, Manoj; Coleman, Bradley; Goldsmith, Elizabeth J; Phillips, Margaret A; Munoz, Benito; Wirth, Dyann F; Klinger, Jeffrey D; Wiegand, Roger; Sybertz, Edmund

    2010-10-22

    Plasmodium falciparum, the causative agent of the most deadly form of human malaria, is unable to salvage pyrimidines and must rely on de novo biosynthesis for survival. Dihydroorotate dehydrogenase (DHODH) catalyzes the rate-limiting step in the pyrimidine biosynthetic pathway and represents a potential target for anti-malarial therapy. A high throughput screen and subsequent medicinal chemistry program identified a series of N-alkyl-5-(1H-benzimidazol-1-yl)thiophene-2-carboxamides with low nanomolar in vitro potency against DHODH from P. falciparum, P. vivax, and P. berghei. The compounds were selective for the parasite enzymes over human DHODH, and x-ray structural data on the analog Genz-667348, demonstrated that species selectivity could be attributed to amino acid differences in the inhibitor-binding site. Compounds from this series demonstrated in vitro potency against the 3D7 and Dd2 strains of P. falciparum, good tolerability and oral exposure in the mouse, and ED(50) values in the 4-day murine P. berghei efficacy model of 13-21 mg/kg/day with oral twice-daily dosing. In particular, treatment with Genz-667348 at 100 mg/kg/day resulted in sterile cure. Two recent analogs of Genz-667348 are currently undergoing pilot toxicity testing to determine suitability as clinical development candidates.

  2. Novel Inhibitors of Plasmodium falciparum Dihydroorotate Dehydrogenase with Anti-malarial Activity in the Mouse Model

    Energy Technology Data Exchange (ETDEWEB)

    Booker, Michael L.; Bastos, Cecilia M.; Kramer, Martin L.; Barker, Jr., Robert H.; Skerlj, Renato; Sidhu, Amar Bir; Deng, Xiaoyi; Celatka, Cassandra; Cortese, Joseph F.; Guerrero Bravo, Jose E.; Crespo Llado, Keila N.; Serrano, Adelfa E.; Angulo-Barturen, Iñigo; Jiménez-Díaz, María Belén; Viera, Sara; Garuti, Helen; Wittlin, Sergio; Papastogiannidis, Petros; Lin, Jing-wen; Janse, Chris J.; Khan, Shahid M.; Duraisingh, Manoj; Coleman, Bradley; Goldsmith, Elizabeth J.; Phillips, Margaret A.; Munoz, Benito; Wirth, Dyann F.; Klinger, Jeffrey D.; Wiegand, Roger; Sybertz, Edmund (Leiden-MC); (Puerto Rico); (STPHI); (Harvard); (GSK); (Genzyme); (UTSMC)

    2010-11-22

    Plasmodium falciparum, the causative agent of the most deadly form of human malaria, is unable to salvage pyrimidines and must rely on de novo biosynthesis for survival. Dihydroorotate dehydrogenase (DHODH) catalyzes the rate-limiting step in the pyrimidine biosynthetic pathway and represents a potential target for anti-malarial therapy. A high throughput screen and subsequent medicinal chemistry program identified a series of N-alkyl-5-(1H-benzimidazol-1-yl)thiophene-2-carboxamides with low nanomolar in vitro potency against DHODH from P. falciparum, P. vivax, and P. berghei. The compounds were selective for the parasite enzymes over human DHODH, and x-ray structural data on the analog Genz-667348, demonstrated that species selectivity could be attributed to amino acid differences in the inhibitor-binding site. Compounds from this series demonstrated in vitro potency against the 3D7 and Dd2 strains of P. falciparum, good tolerability and oral exposure in the mouse, and ED{sub 50} values in the 4-day murine P. berghei efficacy model of 13-21 mg/kg/day with oral twice-daily dosing. In particular, treatment with Genz-667348 at 100 mg/kg/day resulted in sterile cure. Two recent analogs of Genz-667348 are currently undergoing pilot toxicity testing to determine suitability as clinical development candidates.

  3. Generation of antigenic diversity in Plasmodium falciparum by structured rearrangement of Var genes during mitosis.

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    Antoine Claessens

    2014-12-01

    Full Text Available The most polymorphic gene family in P. falciparum is the ∼60 var genes distributed across parasite chromosomes, both in the subtelomeres and in internal regions. They encode hypervariable surface proteins known as P. falciparum erythrocyte membrane protein 1 (PfEMP1 that are critical for pathogenesis and immune evasion in Plasmodium falciparum. How var gene sequence diversity is generated is not currently completely understood. To address this, we constructed large clone trees and performed whole genome sequence analysis to study the generation of novel var gene sequences in asexually replicating parasites. While single nucleotide polymorphisms (SNPs were scattered across the genome, structural variants (deletions, duplications, translocations were focused in and around var genes, with considerable variation in frequency between strains. Analysis of more than 100 recombination events involving var exon 1 revealed that the average nucleotide sequence identity of two recombining exons was only 63% (range: 52.7-72.4% yet the crossovers were error-free and occurred in such a way that the resulting sequence was in frame and domain architecture was preserved. Var exon 1, which encodes the immunologically exposed part of the protein, recombined in up to 0.2% of infected erythrocytes in vitro per life cycle. The high rate of var exon 1 recombination indicates that millions of new antigenic structures could potentially be generated each day in a single infected individual. We propose a model whereby var gene sequence polymorphism is mainly generated during the asexual part of the life cycle.

  4. A Plasmodium falciparum strain expressing GFP throughout the parasite's life-cycle.

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    Arthur M Talman

    Full Text Available The human malaria parasite Plasmodium falciparum is responsible for the majority of malaria-related deaths. Tools allowing the study of the basic biology of P. falciparum throughout the life cycle are critical to the development of new strategies to target the parasite within both human and mosquito hosts. We here present 3D7HT-GFP, a strain of P. falciparum constitutively expressing the Green Fluorescent Protein (GFP throughout the life cycle, which has retained its capacity to complete sporogonic development. The GFP expressing cassette was inserted in the Pf47 locus. Using this transgenic strain, parasite tracking and population dynamics studies in mosquito stages and exo-erythrocytic schizogony is greatly facilitated. The development of 3D7HT-GFP will permit a deeper understanding of the biology of parasite-host vector interactions, and facilitate the development of high-throughput malaria transmission assays and thus aid development of new intervention strategies against both parasite and mosquito.

  5. A simple and fast method to exclude high Plasmodium falciparum parasitaemia in travellers with imported malaria

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    Jacobs Jan

    2011-10-01

    Full Text Available Abstract Background Counts of malaria parasites in peripheral blood are important to assess severity of Plasmodium falciparum malaria. Thin and thick smears are routinely used for this purpose. Methods In this study the Binax NOW® Malaria Test, an easy-to-perform rapid diagnostic test, with Histidine Rich Protein-2 (HRP-2 and aldolase as diagnostic markers, was used for semi-quantitative assessment of parasitaemia of P. faciparum. Results In 257 patients with imported P. falciparum malaria, reactivity of aldolase increased with higher parasitaemia. In all patients with a parasitaemia above 50,000 asexual parasites/μl (> 1% co-reactivity of HRP-2 and aldolase was observed. Absence of aldolase reactivity in the presence of HRP-2 was a reliable predictive marker to exclude high (> 1% parasitaemia in P. falciparum malaria. Conclusions Assessment of HRP-2 and aldolase co-reactivity can be of help in clinical decision making in the acute care setting of returning travellers suspected of having malaria.

  6. Structure of Plasmodium falciparum orotate phosphoribosyltransferase with autologous inhibitory protein–protein interactions

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    Kumar, Shiva; Krishnamoorthy, Kalyanaraman; Mudeppa, Devaraja G.; Rathod, Pradipsinh K., E-mail: rathod@chem.washington.edu [University of Washington, Seattle, WA 98195 (United States)

    2015-04-21

    P. falciparum orotate phosphoribosyltransferase, a potential target for antimalarial drugs and a conduit for prodrugs, crystallized as a structure with eight molecules per asymmetric unit that included some unique parasite-specific auto-inhibitory interactions between catalytic dimers. The most severe form of malaria is caused by the obligate parasite Plasmodium falciparum. Orotate phosphoribosyltransferase (OPRTase) is the fifth enzyme in the de novo pyrimidine-synthesis pathway in the parasite, which lacks salvage pathways. Among all of the malaria de novo pyrimidine-biosynthesis enzymes, the structure of P. falciparum OPRTase (PfOPRTase) was the only one unavailable until now. PfOPRTase that could be crystallized was obtained after some low-complexity sequences were removed. Four catalytic dimers were seen in the asymmetic unit (a total of eight polypeptides). In addition to revealing unique amino acids in the PfOPRTase active sites, asymmetric dimers in the larger structure pointed to novel parasite-specific protein–protein interactions that occlude the catalytic active sites. The latter could potentially modulate PfOPRTase activity in parasites and possibly provide new insights for blocking PfOPRTase functions.

  7. The Clp Chaperones and Proteases of the Human Malaria Parasite Plasmodium falciparum

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    Bakkouri, Majida El; Pow, Andre; Mulichak, Anne; Cheung, Kevin L.Y.; Artz, Jennifer D.; Amani, Mehrnaz; Fell, Stuart; de Koning-Ward, Tania F.; Goodman, C. Dean; McFadden, Geoffrey I.; Ortega, Joaquin; Hui, Raymond; Houry, Walid A. (McMaster U.); (Melbourne); (Toronto); (Deakin); (HWMRI)

    2015-02-09

    The Clp chaperones and proteases play an important role in protein homeostasis in the cell. They are highly conserved across prokaryotes and found also in the mitochondria of eukaryotes and the chloroplasts of plants. They function mainly in the disaggregation, unfolding and degradation of native as well as misfolded proteins. Here, we provide a comprehensive analysis of the Clp chaperones and proteases in the human malaria parasite Plasmodium falciparum. The parasite contains four Clp ATPases, which we term PfClpB1, PfClpB2, PfClpC and PfClpM. One PfClpP, the proteolytic subunit, and one PfClpR, which is an inactive version of the protease, were also identified. Expression of all Clp chaperones and proteases was confirmed in blood-stage parasites. The proteins were localized to the apicoplast, a non-photosynthetic organelle that accommodates several important metabolic pathways in P. falciparum, with the exception of PfClpB2 (also known as Hsp101), which was found in the parasitophorous vacuole. Both PfClpP and PfClpR form mostly homoheptameric rings as observed by size-exclusion chromatography, analytical ultracentrifugation and electron microscopy. The X-ray structure of PfClpP showed the protein as a compacted tetradecamer similar to that observed for Streptococcus pneumoniae and Mycobacterium tuberculosis ClpPs. Our data suggest the presence of a ClpCRP complex in the apicoplast of P. falciparum.

  8. In vitro antiplasmodial activity of marine sponge Clathria vulpina extract against chloroquine sensitive Plasmodium falciparum

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    Sundaram Prasanna Kumar

    2014-02-01

    Full Text Available Objective: To explore the antiplasmodial potential of marine sponge Clathria vulpina (C. vulpina against chloroquine sensitive Plasmodium falciparum (P. falciparum. Methods: The marine sponge C. vulpina was collected from Thondi coast, authenticated and subjected for extraction by soaking in ethanol:water mixture (3:1 ratio. The percentage of extract was calculated. Filter sterilized extracts (100, 50, 25, 12.5, 6.25, 3.125 μg/mL were screened for antiplasmodial activity against chloroquine sensitive P. falciparum. The extract was also tested for its hemolytic activity. Results: The percentage yield of extract of C. vulpina was found to be 4.8%. The crude extract of C. vulpina showed excellent antiplasmodial activity (IC 50=14.75 μg/mL which was highly comparable to the positive control chloroquine (IC50=7 μg/mL. Statistical analysis reveals that the significant antiplasmodial activity (P<0.05 was observed between the concentrations and the time of exposure. The chemical injury to erythrocytes was also carried out, which showed that there were no morphological changes in erythrocytes by the ethanolic extracts of sponges after 48 h of incubation. The extract showed slight hemolytic activity which almost equal to chloroquine at 100 μg/mL concentration (1.023%. Conclusions: The marine sponge C. vulpina can be used as a putative antiplasmodial drug after completing successful clinical trials.

  9. PEST sequences in the malaria parasite Plasmodium falciparum: a genomic study

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    Bell Angus

    2003-06-01

    Full Text Available Abstract Background Inhibitors of the protease calpain are known to have selectively toxic effects on Plasmodium falciparum. The enzyme has a natural inhibitor calpastatin and in eukaryotes is responsible for turnover of proteins containing short sequences enriched in certain amino acids (PEST sequences. The genome of P. falciparum was searched for this protease, its natural inhibitor and putative substrates. Methods The publicly available P. falciparum genome was found to have too many errors to permit reliable analysis. An earlier annotation of chromosome 2 was instead examined. PEST scores were determined for all annotated proteins. The published genome was searched for calpain and calpastatin homologs. Results Typical PEST sequences were found in 13% of the proteins on chromosome 2, including a surprising number of cell-surface proteins. The annotated calpain gene has a non-biological "intron" that appears to have been created to avoid an unrecognized frameshift. Only the catalytic domain has significant similarity with the vertebrate calpains. No calpastatin homologs were found in the published annotation. Conclusion A calpain gene is present in the genome and many putative substrates of this enzyme have been found. Calpastatin homologs may be found once the re-annotation is completed. Given the selective toxicity of calpain inhibitors, this enzyme may be worth exploring further as a potential drug target.

  10. Methylerythritol phosphate pathway to isoprenoids: kinetic modeling and in silico enzyme inhibitions in Plasmodium falciparum.

    Science.gov (United States)

    Singh, Vivek Kumar; Ghosh, Indira

    2013-09-02

    The methylerythritol phosphate (MEP) pathway of Plasmodium falciparum (P. falciparum) has become an attractive target for anti-malarial drug discovery. This study describes a kinetic model of this pathway, its use in validating 1-deoxy-d-xylulose 5-phosphate reductoisomerase (DXR) as drug target from the systemic perspective, and additional target identification, using metabolic control analysis and in silico inhibition studies. In addition to DXR, 1-deoxy-d-xylulose 5-phosphate synthase (DXS) can be targeted because it is the first enzyme of the pathway and has the highest flux control coefficient followed by that of DXR. In silico inhibition of both enzymes caused large decrement in the pathway flux. An added advantage of targeting DXS is its influence on vitamin B1 and B6 biosynthesis. Two more potential targets, 2-C-methyl-d-erythritol 2,4-cyclodiphosphate synthase and 1-hydroxy-2-methyl-2-(E)-butenyl 4-diphosphate synthase, were also identified. Their inhibition caused large accumulation of their substrates causing instability of the system. This study demonstrates that both types of enzyme targets, one acting via flux reduction and the other by metabolite accumulation, exist in P. falciparum MEP pathway. These groups of targets can be exploited for independent anti-malarial drugs. Copyright © 2013 Federation of European Biochemical Societies. Published by Elsevier B.V. All rights reserved.

  11. Effect of fosmidomycin on metabolic and transcript profiles of the methylerythritol phosphate pathway in Plasmodium falciparum

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    María B Cassera

    2007-06-01

    Full Text Available In Plasmodium falciparum, the formation of isopentenyl diphosphate and dimethylallyl diphosphate, central intermediates in the biosynthesis of isoprenoids, occurs via the methylerythritol phosphate (MEP pathway. Fosmidomycin is a specific inhibitor of the second enzyme of the MEP pathway, 1-deoxy-D-xylulose-5-phosphate reductoisomerase. We analyzed the effect of fosmidomycin on the levels of each intermediate and its metabolic requirement for the isoprenoid biosynthesis, such as dolichols and ubiquinones, throughout the intraerythrocytic cycle of P. falciparum. The steady-state RNA levels of the MEP pathway-associated genes were quantified by real-time polymerase chain reaction and correlated with the related metabolite levels. Our results indicate that MEP pathway metabolite peak precede maximum transcript abundance during the intraerythrocytic cycle. Fosmidomycin-treatment resulted in a decrease of the intermediate levels in the MEP pathway as well as in ubiquinone and dolichol biosynthesis. The MEP pathway associated transcripts were modestly altered by the drug, indicating that the parasite is not strongly responsive at the transcriptional level. This is the first study that compares the effect of fosmidomycin on the metabolic and transcript profiles in P. falciparum, which has only the MEP pathway for isoprenoid biosynthesis.

  12. Effect of fosmidomycin on metabolic and transcript profiles of the methylerythritol phosphate pathway in Plasmodium falciparum.

    Science.gov (United States)

    Cassera, María B; Merino, Emilio F; Peres, Valnice J; Kimura, Emilia A; Wunderlich, Gerhard; Katzin, Alejandro M

    2007-06-01

    In Plasmodium falciparum, the formation of isopentenyl diphosphate and dimethylallyl diphosphate, central intermediates in the biosynthesis of isoprenoids, occurs via the methylerythritol phosphate (MEP) pathway. Fosmidomycin is a specific inhibitor of the second enzyme of the MEP pathway, 1-deoxy-D-xylulose-5-phosphate reductoisomerase. We analyzed the effect of fosmidomycin on the levels of each intermediate and its metabolic requirement for the isoprenoid biosynthesis, such as dolichols and ubiquinones, throughout the intraerythrocytic cycle of P. falciparum. The steady-state RNA levels of the MEP pathway-associated genes were quantified by real-time polymerase chain reaction and correlated with the related metabolite levels. Our results indicate that MEP pathway metabolite peak precede maximum transcript abundance during the intraerythrocytic cycle. Fosmidomycin-treatment resulted in a decrease of the intermediate levels in the MEP pathway as well as in ubiquinone and dolichol biosynthesis. The MEP pathway associated transcripts were modestly altered by the drug, indicating that the parasite is not strongly responsive at the transcriptional level. This is the first study that compares the effect of fosmidomycin on the metabolic and transcript profiles in P. falciparum, which has only the MEP pathway for isoprenoid biosynthesis.

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

    Science.gov (United States)

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

    2010-01-01

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

  14. Evidence for a Golgi-to-endosome protein sorting pathway in Plasmodium falciparum.

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    Priscilla Krai

    Full Text Available During the asexual intraerythrocytic stage, the malaria parasite Plasmodium falciparum must traffic newly-synthesized proteins to a broad array of destinations within and beyond the parasite's plasma membrane. In this study, we have localized two well-conserved protein components of eukaryotic endosomes, the retromer complex and the small GTPase Rab7, to define a previously-undescribed endosomal compartment in P. falciparum. Retromer and Rab7 co-localized to a small number of punctate structures within parasites. These structures, which we refer to as endosomes, lie in close proximity to the Golgi apparatus and, like the Golgi apparatus, are inherited by daughter merozoites. However, the endosome is clearly distinct from the Golgi apparatus as neither retromer nor Rab7 redistributed to the endoplasmic reticulum upon brefeldin A treatment. Nascent rhoptries (specialized secretory organelles required for invasion developed adjacent to endosomes, an observation that suggests a role for the endosome in rhoptry biogenesis. A P. falciparum homolog of the sortilin family of protein sorting receptors (PfSortilin was localized to the Golgi apparatus. Together, these results elaborate a putative Golgi-to-endosome protein sorting pathway in asexual blood stage parasites and suggest that one role of retromer is to mediate the retrograde transport of PfSortilin from the endosome to the Golgi apparatus.

  15. Exposure of the Plasmodium falciparum clonally variant STEVOR proteins on the merozoite surface

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    Meri Seppo

    2011-03-01

    Full Text Available Abstract Background Plasmodium falciparum merozoites are free invasive forms that invade host erythrocytes in iterative cycles in the presence of different arms of the immune system. Variant antigens are known to play a role in immune evasion and several gene families coding for variant antigens have been identified in P. falciparum. However, none of them have been reported to be expressed on the surface of merozoites. Methods Flow cytometry, immunofluorescence microscopy, and immunoblotting assays were performed to assess surface exposure, membrane association and stage specific expression of the STEVOR family of variants proteins, respectively. Results Using a polyclonal antibody (anti-PFL2610w with a broad specificity towards different STEVOR variants, the STEVOR proteins were identified on the surface of non-permeabilized/non-fixed merozoites in flow cytometry assays. Anti-PFL2610w antibody showed that several STEVORs were expressed in the trophozoite stage of the parasite but only one variant was integrated into the merozoite membrane. Moreover, this antibody failed to identify STEVORs on the surface of the parent schizont infected erythrocytes (IE although they were readily identified when schizont IE were permeabilized. Conclusions These data suggest for a role for STEVOR in immune evasion by P. falciparum merozoites to allow successful invasion of erythrocytes. Additionally, the expression of STEVORs in the schizont stage may only represent a step in the biogenesis process of the merozoite surface coat.

  16. Taxonomy Icon Data: malaria parasite P. falciparum [Taxonomy Icon

    Lifescience Database Archive (English)

    Full Text Available malaria parasite P. falciparum Plasmodium falciparum Plasmodium_falciparum_L.png Plasmodium_falciparum..._NL.png Plasmodium_falciparum_S.png Plasmodium_falciparum_NS.png http://biosciencedbc.jp/...taxonomy_icon/icon.cgi?i=Plasmodium+falciparum&t=L http://biosciencedbc.jp/taxonomy_icon/icon.cgi?i=Plasmodium+falciparum...&t=NL http://biosciencedbc.jp/taxonomy_icon/icon.cgi?i=Plasmodium+falciparum...&t=S http://biosciencedbc.jp/taxonomy_icon/icon.cgi?i=Plasmodium+falciparum&t=NS http://togodb.biosciencedbc.jp/togodb/view/taxonomy_icon_comment_en?species_id=218 ...

  17. Yurt Dışı Kökenli Plasmodium falciparum Suşlarının Tanısında Serolojik ve Moleküler Yöntemlerin Kullanılması

    OpenAIRE

    Eroglu, Fadime; Genç, Ahmet; Çürük, Mehmet Akif; Koltaş, İsmail Soner

    2018-01-01

    ÖzetPlasmodium falciparum, sıtmaya neden olan Plasmodium türlerinden biridir. Plasmodium falciparum sıtması, sıtma çeşitleri içerisinde ölüm oranı en yüksek ve en tehlikeli olandır. Bu nedenle Plasmodium falciparum sıtmasının erken tanısı çok önemlidir. Anahtar Kelime: Plasmodium falciparum, serolojik tanı, moleküler tanıThe Use of Serological and Molecular Methods in Diagnosis of Foreign Origin Plasmodium falciparum StrainsAbstractPlasmodium falciparum is a protozoan parasite, one of the spe...

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

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    Elisabeth Silberhorn

    2016-12-01

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

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

    Science.gov (United States)

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

    2016-01-01

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

  20. Identification of a novel and unique transcription factor in the intraerythrocytic stage of Plasmodium falciparum.

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    Kanako Komaki-Yasuda

    Full Text Available The mechanisms of stage-specific gene regulation in the malaria parasite Plasmodium falciparum are largely unclear, with only a small number of specific regulatory transcription factors (AP2 family having been identified. In particular, the transcription factors that function in the intraerythrocytic stage remain to be elucidated. Previously, as a model case for stage-specific transcription in the P. falciparum intraerythrocytic stage, we analyzed the transcriptional regulation of pf1-cys-prx, a trophozoite/schizont-specific gene, and suggested that some nuclear factors bind specifically to the cis-element of pf1-cys-prx and enhance transcription. In the present study, we purified nuclear factors from parasite nuclear extract by 5 steps of chromatography, and identified a factor termed PREBP. PREBP is not included in the AP2 family, and is a novel protein with four K-homology (KH domains. The KH domain is known to be found in RNA-binding or single-stranded DNA-binding proteins. PREBP is well conserved in Plasmodium species and partially conserved in phylum Apicomplexa. To evaluate the effects of PREBP overexpression, we used a transient overexpression and luciferase assay combined approach. Overexpression of PREBP markedly enhanced luciferase expression under the control of the pf1-cys-prx cis-element. These results provide the first evidence of a novel transcription factor that activates the gene expression in the malaria parasite intraerythrocytic stage. These findings enhance our understanding of the evolution of specific transcription machinery in Plasmodium and other eukaryotes.

  1. Antibody reactivity to conserved linear epitopes of Plasmodium falciparum erythrocyte membrane protein 1 (PfEMP1)

    DEFF Research Database (Denmark)

    Staalsø, T; Khalil, E A; Elhassan, I M

    1998-01-01

    The Plasmodium falciparum erythrocyte membrane protein 1 (PfEMP1) family of protein antigens are involved in adhesion of P. falciparum infected erythrocytes to the capillary endothelium of the host. Antibodies to variable regions of these proteins, measured by agglutination, correlates with clini......The Plasmodium falciparum erythrocyte membrane protein 1 (PfEMP1) family of protein antigens are involved in adhesion of P. falciparum infected erythrocytes to the capillary endothelium of the host. Antibodies to variable regions of these proteins, measured by agglutination, correlates...

  2. Polymorphism of Plasmodium Falciparum Dihydrofolate Reductase and Dihydropteroate Synthase Genes among Pregnant Women with Falciparum Malaria in Banjar District, South Kalimantan Province, Indonesia

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    Sukmawati Basuki

    2012-12-01

    Full Text Available Pregnant women are highly vulnerable to malaria infection in its endemic areas, particularly infection by Plasmodium falciparum that can cause premature, low birth weight, severe anemia in pregnant women, and death. Sulfadoxine-pyrimethamine (SP for Intermittent Preventive Treatment for pregnant (IPTp is used for malaria control in pregnancy recommended by the World Health Organization that has already been implemented in Africa. The P. falciparum resistance to SP has been reported in several malarial endemic areas, and mutations in the genes of Plasmodium falciparum Dihydrofolate Reductase (Pfdhfr and Dihydropteroate Synthase (Pfdhps are shown to be associated with parasite resistance to SP treatment. Genetic analysis of Pfdhfr and Pfdhps genes in pregnant women infected with P. falciparum has not yet been examined in Indonesia. The cross-sectional study was conducted at two subdistricts, Sungai Pinang and Peramasan, in Banjar district of South Kalimantan Province, where 127 pregnant women were recruited from 2008 to April 2010. Two important mutations in Pfdhfr gene (amino acid positions at N51 and S108 and three in Pfdhps gene (A437, K540 and A581 were analyzed by nested PCR-RFLP method. All of the seven pregnant women samples infected with P. falciparum presented PfDHFR 108N and PfDHPS 437G mutations. One of the samples had the additional mutation at PfDHPS 540, in which Lys is substituted by Glu. These results suggested that P. falciparum might present only some resistance to SP at Sungai Pinang and Peramasan subdistricts, Banjar District, South Kalimantan province, Indonesia. Although there were limited number of samples, this study showed only few mutations of Pfdhfr and Pfdhps genes in P. falciparum at Banjar district, South Kalimantan Province, that suggests SP might be effective for IPTp in this area. Thus, further analysis of the other mutation sites in Pfdhfr and Pfdhps genes and in vivo efficacy study of SP with more sufficient

  3. Antioxidant vitamin levels among preschool children with uncomplicated Plasmodium falciparum malaria in Sokoto, Nigeria

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    Aghedo FI

    2013-07-01

    Full Text Available Festus I Aghedo,1 Resqua A Shehu,2 Rabiu A Umar,2 Mohammed N Jiya,3 Osaro Erhabor4 1Department of Haematology, Usmanu Danfodiyo University Teaching Hospital, Sokoto, Nigeria; 2Department of Biochemistry, Usmanu Danfodiyo University, Sokoto, Nigeria; 3Department of Paediatrics, College of Health Sciences, Usmanu Danfodiyo University, Sokoto, Nigeria; 4Department of Haematology, Faculty of Medical Laboratory Science, Usmanu Danfodiyo University, Sokoto, Nigeria Objective: To assess antioxidant vitamin levels among preschool children with plasmodium malarial infection. Methods: We assessed antioxidant vitamin levels by using a standard procedure in 130 malaria-parasitized preschool children. Packed cell volume and parasite density were also evaluated. Forty healthy age- and gender-matched nonparasitized children were included as controls. Results: Plasmodium falciparum was the causative species in all subjects. The mean malaria parasitemia was 4529.45 ± 1237.5/µL. The mean antioxidant concentrations for vitamins A, C, and E among plasmodium-parasitized subjects were 33.15 ± 1.79 µg/dL, 0.51 ± 0.02 mg/dL, and 0.61 ± 0.02 mg/dL, respectively. The mean concentrations of vitamins A, C, and E among the non-malaria-parasitized controls were 69.72 ± 1.71 µg/dL, 1.25 ± 0.04 mg/dL, and 1.31 ± 0.04 mg/dL respectively. We observed that the mean antioxidant concentrations of vitamins A, C, and E were significantly lower among plasmodium-parasitized subjects compared with non-parasitized controls (P = 0.01. Malaria parasitemia correlated negatively with antioxidant concentrations and packed cell volume (r = -0.736 and -0.723, P = 0.001. We observed that the higher the level of parasitemia, the lower the antioxidant concentration. Conclusion: Our study has shown that the antioxidant levels in plasmodium-parasitized children in the North-West of Nigeria are low and that the more severe the malarial infection, the lower the antioxidant level and the

  4. Plasmodium falciparum and intestinal parasitic co-infections in HIV-infected patients in Benin City, Edo State, Nigeria.

    Science.gov (United States)

    Akinbo, Frederick Olusegun; Okaka, Christopher Ehis; Omoregie, Richard

    2012-05-14

    Human co-infection with Plasmodium falciparum and helminthes is ubiquitous throughout Africa. This study aimed to determine the co-infections of Plasmodium falciparum infection in HIV and intestinal parasitic infections, and their immunological distribution, in Benin City, Nigeria. A total of 2,000 stool specimens from HIV-positive patients and 500 controls (HIV-negative individuals) were examined for ova, cysts, or parasites using standard procedures. In addition, patients' blood samples were analyzed for CD4 counts by flow cytometry and examined for Plasmodium falciparum by microscopy. The prevalence of single parasitic infection among HIV patients was 18.1% in males and 16.9% among females with no significant difference (p = 0.536) while gender was a risk factor in multiple parasitic infections (male versus female: 4.2% and 1.8% OR = 2.384; 95% CI = 1.371, 4.147) (p = 0.0025). Increasing age was not associated with increased risk of both single and multiple parasitic infections (p = 0.083; p = 0.248). CD4 + T cell count less than 200 cells/µl was a risk factor for acquiring single and multiple parasitic infections among HIV patients (OR = 5.565; 95% CI = 4.136, 7.486; p = 0.0001; OR = 4.283; 95% CI = 2.424, 7.566; p = 0.0001). The most common co-infection observed was between Plasmodium falciparum and Ascaris lumbricoides 43% (10) among HIV patients. This study provides evidence of co-infections between Plasmodium falciparum and intestinal parasites. Diagnosis of parasitic infections among HIV patients is advocated as this will enhance better management of HIV-infected patients.

  5. Comparative analysis of stage specific gene regulation of apicomplexan parasites: Plasmodium falciparum and Toxoplasma gondii.

    Science.gov (United States)

    Gopalakrishnan, Anusha M; López-Estraño, Carlos

    2010-08-01

    Apicomplexans comprise some of the most life threatening parasites infecting human and livestock and includes Plasmodium and Toxoplasma, the causative agents of malaria and toxoplasmosis respectively, in humans as well as Neospora caninum (abortion in livestock, neosporosis in dogs), Cryptosporidium (Diarrheal cryptosporidiosis and opportunistic infections in AIDS patients) and Eimeria (poultry coccidiosis). These parasites are characterized by a complex life cycle usually alternating between sexual and asexual cycles in different hosts. The need to adapt to different host environments demands a tight regulation of gene expression during parasite development. Therefore, the understanding of parasite biology will facilitate the control of the infection and the disease. In this review we emphasize the progress made so far in gene regulation in two medically important parasites, namely Plasmodium falciparum and Toxoplasma gondii, as well as other less known apicomplexan. The genome of both Plasmodium and Toxoplasma has been sequenced and since then there has been a significant progress in understanding the molecular mechanisms that control stage specific gene expression in the two parasites. In addition, the information gained in each of the parasite can be used in studying mechanisms that are still elusive in the other apicomplexans that are not readily available. Additionally, they can serve as model system for other disease causing Apicomplexan parasites.

  6. Perfil clínico y parasitológico de la malaria por Plasmodium falciparum y Plasmodium vivax no complicada en Córdoba, Colombia

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    Angélica Knudson-Ospina

    2015-10-01

    Full Text Available Antecedentes. En Colombia existen pocos estudios que buscan encontrar diferencias clínicas y parasitológicas en la malaria causada por Plasmodium falciparum y Plasmodium vivax. Objetivo. Describir el perfil clínico y parasitológico de las malarias por Plasmodium falciparum y Plasmodium vivax no complicadas en Tierralta, Córdoba, Colombia. Materiales y métodos. Se evaluaron pacientes con paludismo no complicado por Plasmodium falciparum y Plasmodium vivax según los protocolos estandarizados por la Organización Panamericana de la Salud y se recolectó información clínica y parasitológica. De igual forma, se utilizó análisis multivariado por correspondencias múltiples para describir diferentes perfiles de pacientes con paludismo no complicado por estas dos especies antes de recibir tratamiento. Resultados. Se evaluaron 112 pacientes con edad entre 6 y 64 años, 59 (52.7% con Plasmodium falciparum y 53 (47.3% con Plasmodium vivax. Los síntomas más frecuentes fueron fiebre en 111 pacientes (99.1%; IC 95%: 81.5-100, sudoración en 105 (93.8%; IC 95%: 76.7-100 y dolor osteomuscular en 105 (93.8%; IC 95%: 76.7-100. Se presentaron con mayor frecuencia, y con diferencia significativa, en las infecciones por Plasmodium falciparum: diarrea en 18 pacientes (30.5%; IC 95%: 18.1-48.2; decaimiento en 49 (83%; IC 95%: 61.4-109.8; palidez palmar en 39 (66.1%; IC 95%: 47-90.4 y sequedad de mucosas en 12 (20.3%; IC 95%: 10.5-35.5. El escalofrío se presentó con mayor frecuencia en Plasmodium vivax (98.1%; IC 95%: 73.4-128.1. El análisis multivariado agrupó las variables en cuatro perfiles distintos de presentaciones clínicas así: 1 síntomas clínicos y su relación con el recuento parasitario, 2 características clínicas en relación con la edad y sexo, 3 antecedentes de malaria en relación con características demográficas y clínicas y 4 especie del parásito en relación con antecedentes, clínica y variables demográficas. Conclusi

  7. Detection of high levels of mutations involved in anti-malarial drug resistance in Plasmodium falciparum and Plasmodium vivax at a rural hospital in southern Ethiopia

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    González Vicenta

    2011-08-01

    Full Text Available Abstract Background In Ethiopia, malaria is caused by Plasmodium falciparum and Plasmodium vivax, and anti-malarial drug resistance is the most pressing problem confronting control of the disease. Since co-infection by both species of parasite is common and sulphadoxine-pyrimethamine (SP has been intensively used, resistance to these drugs has appeared in both P. falciparum and P. vivax populations. This study was conducted to assess the prevalence of anti-malarial drug resistance in P. falciparum and P. vivax isolates collected at a rural hospital in southern Ethiopia. Methods A total of 1,147 patients with suspected malaria were studied in different months across the period 2007-2009. Plasmodium falciparum dhfr and dhps mutations and P. vivax dhfr polymorphisms associated with resistance to SP, as well as P. falciparum pfcrt and pfmdr1 mutations conferring chloroquine resistance, were assessed. Results PCR-based diagnosis showed that 125 of the 1147 patients had malaria. Of these, 52.8% and 37.6% of cases were due to P. falciparum and P. vivax respectively. A total of 10 cases (8% showed co-infection by both species and two cases (1.6% were infected by Plasmodium ovale. Pfdhfr triple mutation and pfdhfr/pfdhps quintuple mutation occurred in 90.8% (95% confidence interval [CI]: 82.2%-95.5% and 82.9% (95% CI: 72.9%-89.7% of P. falciparum isolates, respectively. Pfcrt T76 was observed in all cases and pfmdr1 Y86 and pfmdr1 Y1246 in 32.9% (95% CI: 23.4%-44.15% and 17.1% (95% CI: 10.3-27.1%, respectively. The P. vivax dhfr core mutations, N117 and R58, were present in 98.2% (95% CI: 89.4-99.9% and 91.2% (95% CI: 80.0-96.7%, respectively. Conclusion Current molecular data show an extraordinarily high frequency of drug-resistance mutations in both P. falciparum and P. vivax in southern Ethiopia. Urgent surveillance of the emergence and spread of resistance is thus called for. The level of resistance indicates the need for implementation of entire

  8. Conserved mosquito/parasite interactions affect development of Plasmodium falciparum in Africa.

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    Antonio M Mendes

    2008-05-01

    Full Text Available In much of sub-Saharan Africa, the mosquito Anopheles gambiae is the main vector of the major human malaria parasite, Plasmodium falciparum. Convenient laboratory studies have identified mosquito genes that affect positively or negatively the developmental cycle of the model rodent parasite, P. berghei. Here, we use transcription profiling and reverse genetics to explore whether five disparate mosquito gene regulators of P. berghei development are also pertinent to A. gambiae/P. falciparum interactions in semi-natural conditions, using field isolates of this parasite and geographically related mosquitoes. We detected broadly similar albeit not identical transcriptional responses of these genes to the two parasite species. Gene silencing established that two genes affect similarly both parasites: infections are hindered by the intracellular local activator of actin cytoskeleton dynamics, WASP, but promoted by the hemolymph lipid transporter, ApoII/I. Since P. berghei is not a natural parasite of A. gambiae, these data suggest that the effects of these genes have not been drastically altered by constant interaction and co-evolution of A. gambiae and P. falciparum; this conclusion allowed us to investigate further the mode of action of these two genes in the laboratory model system using a suite of genetic tools and infection assays. We showed that both genes act at the level of midgut invasion during the parasite's developmental transition from ookinete to oocyst. ApoII/I also affects the early stages of oocyst development. These are the first mosquito genes whose significant effects on P. falciparum field isolates have been established by direct experimentation. Importantly, they validate for semi-field human malaria transmission the concept of parasite antagonists and agonists.

  9. Antimalarial activity of potential inhibitors of Plasmodium falciparum lactate dehydrogenase enzyme selected by docking studies.

    Science.gov (United States)

    Penna-Coutinho, Julia; Cortopassi, Wilian Augusto; Oliveira, Aline Alves; França, Tanos Celmar Costa; Krettli, Antoniana Ursine

    2011-01-01

    The Plasmodium falciparum lactate dehydrogenase enzyme (PfLDH) has been considered as a potential molecular target for antimalarials due to this parasite's dependence on glycolysis for energy production. Because the LDH enzymes found in P. vivax, P. malariae and P. ovale (pLDH) all exhibit ∼90% identity to PfLDH, it would be desirable to have new anti-pLDH drugs, particularly ones that are effective against P. falciparum, the most virulent species of human malaria. Our present work used docking studies to select potential inhibitors of pLDH, which were then tested for antimalarial activity against P. falciparum in vitro and P. berghei malaria in mice. A virtual screening in DrugBank for analogs of NADH (an essential cofactor to pLDH) and computational studies were undertaken, and the potential binding of the selected compounds to the PfLDH active site was analyzed using Molegro Virtual Docker software. Fifty compounds were selected based on their similarity to NADH. The compounds with the best binding energies (itraconazole, atorvastatin and posaconazole) were tested against P. falciparum chloroquine-resistant blood parasites. All three compounds proved to be active in two immunoenzymatic assays performed in parallel using monoclonals specific to PfLDH or a histidine rich protein (HRP2). The IC(50) values for each drug in both tests were similar, were lowest for posaconazole (<5 µM) and were 40- and 100-fold less active than chloroquine. The compounds reduced P. berghei parasitemia in treated mice, in comparison to untreated controls; itraconazole was the least active compound. The results of these activity trials confirmed that molecular docking studies are an important strategy for discovering new antimalarial drugs. This approach is more practical and less expensive than discovering novel compounds that require studies on human toxicology, since these compounds are already commercially available and thus approved for human use.

  10. Antimalarial activity of potential inhibitors of Plasmodium falciparum lactate dehydrogenase enzyme selected by docking studies.

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    Julia Penna-Coutinho

    Full Text Available The Plasmodium falciparum lactate dehydrogenase enzyme (PfLDH has been considered as a potential molecular target for antimalarials due to this parasite's dependence on glycolysis for energy production. Because the LDH enzymes found in P. vivax, P. malariae and P. ovale (pLDH all exhibit ∼90% identity to PfLDH, it would be desirable to have new anti-pLDH drugs, particularly ones that are effective against P. falciparum, the most virulent species of human malaria. Our present work used docking studies to select potential inhibitors of pLDH, which were then tested for antimalarial activity against P. falciparum in vitro and P. berghei malaria in mice. A virtual screening in DrugBank for analogs of NADH (an essential cofactor to pLDH and computational studies were undertaken, and the potential binding of the selected compounds to the PfLDH active site was analyzed using Molegro Virtual Docker software. Fifty compounds were selected based on their similarity to NADH. The compounds with the best binding energies (itraconazole, atorvastatin and posaconazole were tested against P. falciparum chloroquine-resistant blood parasites. All three compounds proved to be active in two immunoenzymatic assays performed in parallel using monoclonals specific to PfLDH or a histidine rich protein (HRP2. The IC(50 values for each drug in both tests were similar, were lowest for posaconazole (<5 µM and were 40- and 100-fold less active than chloroquine. The compounds reduced P. berghei parasitemia in treated mice, in comparison to untreated controls; itraconazole was the least active compound. The results of these activity trials confirmed that molecular docking studies are an important strategy for discovering new antimalarial drugs. This approach is more practical and less expensive than discovering novel compounds that require studies on human toxicology, since these compounds are already commercially available and thus approved for human use.

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

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    Pinto João

    2010-06-01

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

  12. Impact of child malnutrition on the specific anti-Plasmodium falciparum antibody response

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    Fillol Florie

    2009-06-01

    Full Text Available Abstract Background In sub-Saharan Africa, preschool children represent the population most vulnerable to malaria and malnutrition. It is widely recognized that malnutrition compromises the immune function, resulting in higher risk of infection. However, very few studies have investigated the relationship between malaria, malnutrition and specific immunity. In the present study, the anti-Plasmodium falciparum IgG antibody (Ab response was evaluated in children according to the type of malnutrition. Methods Anthropometric assessment and blood sample collection were carried out during a cross-sectional survey including rural Senegalese preschool children. This cross-sectional survey was conducted in July 2003 at the onset of the rainy season. Malnutrition was defined as stunting (height-for-age P. falciparum whole extracts (schizont antigens was assessed by ELISA in sera of the included children. Results Both the prevalence of anti-malarial immune responders and specific IgG Ab levels were significantly lower in malnourished children than in controls. Depending on the type of malnutrition, wasted children and stunted children presented a lower specific IgG Ab response than their respective controls, but this difference was significant only in stunted children (P = 0.026. This down-regulation of the specific Ab response seemed to be explained by severely stunted children (HAZ ≤ -2.5 compared to their controls (P = 0.03, while no significant difference was observed in mildly stunted children (-2.5 P. falciparum Ab response appeared to be independent of the intensity of infection. Conclusion Child malnutrition, and particularly stunting, may down-regulate the anti-P. falciparum Ab response, both in terms of prevalence of immune responders and specific IgG Ab levels. This study provides further evidence for the influence of malnutrition on the specific anti-malarial immune response and points to the importance of taking into account child

  13. Cellulose filtration of blood from malaria patients for improving ex vivo growth of Plasmodium falciparum parasites.

    Science.gov (United States)

    Mkumbaye, Sixbert I; Minja, Daniel T R; Jespersen, Jakob S; Alifrangis, Michael; Kavishe, Reginald A; Mwakalinga, Steven B; Lusingu, John P; Theander, Thor G; Lavstsen, Thomas; Wang, Christian W

    2017-02-10

    Establishing in vitro Plasmodium falciparum culture lines from patient parasite isolates can offer deeper understanding of geographic variations of drug sensitivity and mechanisms of malaria pathogenesis and immunity. Cellulose column filtration of blood is an inexpensive, rapid and effective method for the removal of host factors, such as leucocytes and platelets, significantly improving the purification of parasite DNA in a blood sample. In this study, the effect of cellulose column filtration of venous blood on the initial in vitro growth of P. falciparum parasite isolates from Tanzanian children admitted to hospital was tested. The parasites were allowed to expand in culture without subcultivation until 5 days after admission or the appearance of dead parasites and parasitaemia was determined daily. To investigate whether the filtration had an effect on clonality, P. falciparum merozoite surface protein 2 genotyping was performed using nested PCR on extracted genomic DNA, and the var gene transcript levels were investigated, using quantitative PCR on extracted RNA, at admission and 4 days of culture. The cellulose-filtered parasites grew to higher parasitaemia faster than non-filtered parasites seemingly due to a higher development ratio of ring stage parasites progressing into the late stages. Cellulose filtration had no apparent effect on clonality or var gene expression; however, evident differences were observed after only 4 days of culture in both the number of clones and transcript levels of var genes compared to the time of admission. Cellulose column filtration of parasitized blood is a cheap, applicable method for improving cultivation of P. falciparum field isolates for ex vivo based assays; however, when assessing phenotype and genotype of cultured parasites, in general, assumed to represent the in vivo infection, caution is advised.

  14. Effect of acute Plasmodium falciparum malaria on reactivation and shedding of the eight human herpes viruses.

    Directory of Open Access Journals (Sweden)

    Arnaud Chêne

    Full Text Available Human herpes viruses (HHVs are widely distributed pathogens. In immuno-competent individuals their clinical outcomes are generally benign but in immuno-compromised hosts, primary infection or extensive viral reactivation can lead to critical diseases. Plasmodium falciparum malaria profoundly affects the host immune system. In this retrospective study, we evaluated the direct effect of acute P. falciparum infection on reactivation and shedding of all known human herpes viruses (HSV-1, HSV-2, VZV, EBV, CMV, HHV-6, HHV-7, HHV-8. We monitored their presence by real time PCR in plasma and saliva of Ugandan children with malaria at the day of admission to the hospital (day-0 and 14 days later (after treatment, or in children with mild infections unrelated to malaria. For each child screened in this study, at least one type of HHV was detected in the saliva. HHV-7 and HHV-6 were detected in more than 70% of the samples and CMV in approximately half. HSV-1, HSV-2, VZV and HHV-8 were detected at lower frequency. During salivary shedding the highest mean viral load was observed for HSV-1 followed by EBV, HHV-7, HHV-6, CMV and HHV-8. After anti-malarial treatment the salivary HSV-1 levels were profoundly diminished or totally cleared. Similarly, four children with malaria had high levels of circulating EBV at day-0, levels that were cleared after anti-malarial treatment confirming the association between P. falciparum infection and EBV reactivation. This study shows that acute P. falciparum infection can contribute to EBV reactivation in the blood and HSV-1 reactivation in the oral cavity. Taken together our results call for further studies investigating the potential clinical implications of HHVs reactivation in children suffering from malaria.

  15. Global mass spectrometry based metabolomics profiling of erythrocytes infected with Plasmodium falciparum.

    Directory of Open Access Journals (Sweden)

    Theodore R Sana

    Full Text Available Malaria is a global infectious disease that threatens the lives of millions of people. Transcriptomics, proteomics and functional genomics studies, as well as sequencing of the Plasmodium falciparum and Homo sapiens genomes, have shed new light on this host-parasite relationship. Recent advances in accurate mass measurement mass spectrometry, sophisticated data analysis software, and availability of biological pathway databases, have converged to facilitate our global, untargeted biochemical profiling study of in vitro P. falciparum-infected (IRBC and uninfected (NRBC erythrocytes. In order to expand the number of detectable metabolites, several key analytical steps in our workflows were optimized. Untargeted and targeted data mining resulted in detection of over one thousand features or chemical entities. Untargeted features were annotated via matching to the METLIN metabolite database. For targeted data mining, we queried the data using a compound database derived from a metabolic reconstruction of the P. falciparum genome. In total, over one hundred and fifty differential annotated metabolites were observed. To corroborate the representation of known biochemical pathways from our data, an inferential pathway analysis strategy was used to map annotated metabolites onto the BioCyc pathway collection. This hypothesis-generating approach resulted in over-representation of many metabolites onto several IRBC pathways, most prominently glycolysis. In addition, components of the "branched" TCA cycle, partial urea cycle, and nucleotide, amino acid, chorismate, sphingolipid and fatty acid metabolism were found to be altered in IRBCs. Interestingly, we detected and confirmed elevated levels for cyclic ADP ribose and phosphoribosyl AMP in IRBCs, a novel observation. These metabolites may play a role in regulating the release of intracellular Ca(2+ during P. falciparum infection. Our results support a strategy of global metabolite profiling by untargeted

  16. Plasmodium falciparum heterochromatin protein 1 marks genomic loci linked to phenotypic variation of exported virulence factors.

    Directory of Open Access Journals (Sweden)

    Christian Flueck

    2009-09-01

    Full Text Available Epigenetic processes are the main conductors of phenotypic variation in eukaryotes. The malaria parasite Plasmodium falciparum employs antigenic variation of the major surface antigen PfEMP1, encoded by 60 var genes, to evade acquired immune responses. Antigenic variation of PfEMP1 occurs through in situ switches in mono-allelic var gene transcription, which is PfSIR2-dependent and associated with the presence of repressive H3K9me3 marks at silenced loci. Here, we show that P. falciparum heterochromatin protein 1 (PfHP1 binds specifically to H3K9me3 but not to other repressive histone methyl marks. Based on nuclear fractionation and detailed immuno-localization assays, PfHP1 constitutes a major component of heterochromatin in perinuclear chromosome end clusters. High-resolution genome-wide chromatin immuno-precipitation demonstrates the striking association of PfHP1 with virulence gene arrays in subtelomeric and chromosome-internal islands and a high correlation with previously mapped H3K9me3 marks. These include not only var genes, but also the majority of P. falciparum lineage-specific gene families coding for exported proteins involved in host-parasite interactions. In addition, we identified a number of PfHP1-bound genes that were not enriched in H3K9me3, many of which code for proteins expressed during invasion or at different life cycle stages. Interestingly, PfHP1 is absent from centromeric regions, implying important differences in centromere biology between P. falciparum and its human host. Over-expression of PfHP1 results in an enhancement of variegated expression and highlights the presence of well-defined heterochromatic boundaries. In summary, we identify PfHP1 as a major effector of virulence gene silencing and phenotypic variation. Our results are instrumental for our understanding of this widely used survival strategy in unicellular pathogens.

  17. HOMOLOGY MODELLING AND BINDING SITE IDENTIFICATION OF 1DEOXY D-XYLULOSE 5 PHOSPHATE REDUCTOISOMERASE OF PLASMODIUM FALCIPARUM: NEW DRUG TARGET FOR PLSMODIUM FALCIPARUM

    OpenAIRE

    JYOTSNA CHOUBEY; ASHISH PATEL; Verma, M. K.; SHAILENDRA GUPTA

    2010-01-01

    Malaria is major global health problem. Malaria parasite had developed resistance to the drug being used till date. It implies the development of new effective drug with different mode of action. Apicoplast in malaria and related parasite offer various new target for drug therapy[1]. Apicoplast contains various metabolic pathways that differ from those of host thereby presenting ideal strategies for drug therapy. Plasmodium falciparum 1deoxy- Dxylulose 5- phosphate reductoisomerase (pfDXR) is...

  18. Survey of Plasmodium falciparum multidrug resistance-1 and chloroquine resistance transporter alleles in Haiti.

    Science.gov (United States)

    Elbadry, Maha A; Existe, Alexandre; Victor, Yves S; Memnon, Gladys; Fukuda, Mark; Dame, John B; Yowell, Charles A; Okech, Bernard A

    2013-11-19

    In Haiti where chloroquine (CQ) is widely used for malaria treatment, reports of resistance are scarce. However, recent identification of CQ resistance genotypes in one site is suggestive of an emerging problem. Additional studies are needed to evaluate genetic mutations associated with CQ resistance, especially in the Plasmodium falciparum multi-drug resistance-1 gene (pfmdr1) while expanding the already available information on P. falciparum CQ transporter gene (pfcrt) in Haiti. Blood samples were collected on Whatman filter cards (FTA) from eight clinics spread across Haiti. Following the confirmation of P. falciparum in the samples, PCR protocols were used to amplify regions of pfmdr1and pfcrt codons of interest, (86, 184, 1034, 1042, and 1246) and (72-76), respectively. Sequencing and site-specific restriction enzyme digestions were used to analyse these DNA fragments for the presence of single nucleotide polymorphisms (SNPs) known to confer resistance to anti-malarial drugs. P. falciparum infection was confirmed in160 samples by amplifying a segment of the P. falciparum 18S small subunit ribosomal RNA gene (pfssurrna). The sequence of pfmdr1 in 54 of these samples was determined between codons 86,184 codons 1034, 1042 and 1246. No sequence differences from that of the NF54 clone 3D7 were found among the 54 samples except at codon 184, where a non-silent mutation was found in all samples predicted to alter the amino acid sequence replacing tyrosine with phenylalanine (Y184F). This altered sequence was also confirmed by restriction enzyme digestion. The sequence of pfmdr1 at codons 86, 184, 1034 and 1042 encoded the NFSN haplotype. The sequence of pfcrt codons 72-76 from 79 samples was determined and found to encode CVMNK, consistent with a CQ sensitive genotype. The presence of the Y184F mutation in pfmdr1 of P. falciparum parasites in Haiti may have implications for resistance to antimalarial drugs. The absence of mutation in pfcrt at codon 76 among 79

  19. Activity of Ocimum basilicum, Ocimum canum, and Cymbopogon citratus essential oils against Plasmodium falciparum and mature-stage larvae of Anopheles funestus s.s

    National Research Council Canada - National Science Library

    Akono Ntonga, Patrick; Baldovini, Nicolas; Mouray, Elisabeth; Mambu, Lengo; Belong, Philippe; Grellier, Philippe

    2014-01-01

    The biological activities of essential oils from three plants grown in Cameroon: Ocimum basilicum, Ocimum canum, and Cymbopogon citratus were tested against Plasmodium falciparum and mature-stage larvae of Anopheles funestus...

  20. Identification of a major rif transcript common to gametocytes and sporozoites of Plasmodium falciparum

    DEFF Research Database (Denmark)

    Wang, Christian W; Mwakalinga, Steven B; Sutherland, Colin J

    2010-01-01

    ABSTRACT: BACKGROUND: The Plasmodium falciparum parasite is transmitted in its sexual gametocyte stage from man to mosquito and as asexual sporozoites from mosquito to man. Developing gametocytes sequester preferentially in the bone marrow, but mature stage gametocytes are released...