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Sample records for plasmodium falciparum strains

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

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    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.

  2. 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.

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

    KAUST Repository

    Subudhi, Amit Kumar

    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.

  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. Membrane rigidity of red blood cells parasitized by different strains of Plasmodium falciparum.

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    Paulitschke, M; Nash, G B

    1993-11-01

    Changes in the structure of parasitized red blood cells may influence their ability to circulate. We have used a micropipette technique to examine the effects of invasion and maturation of Plasmodium falciparum on the membrane rigidity of red blood cells. In the presence of immature, ring form parasites from different laboratory strains, membrane rigidity remained unchanged as compared with uninfected red cells. However, development of more mature pigmented trophozoites caused a marked increase in membrane rigidity. Parasites from knobless strains caused a less-pronounced increase than parasites from knob-positive strains. Using closely synchronized cultures, the dependence of membrane rigidity on parasite maturation was studied in more detail for selected knob-positive and knobless strains. Over a period of 12 hours, while trophozoites developed into schizonts, no further rigidification of the red cell membrane occurred. The increase in membrane rigidity, occurring with the initial development of pigmented trophozoites, may be related to insertion of neoantigens into the red cell surface or modification of native membrane proteins that also occur at this time. In contrast to others, we found no effect of parasite-culture supernatant, harvested at different stages, on the rigidity of uninfected cells exposed to it. Interstrain variation of membrane rigidity could influence pathophysiology in several ways: by promoting margination and cytoadherence of knob-positive strains in the microcirculation, by modulating clearance of parasitized cells by the reticuloendothelial system, and by influencing ischemic complications of severe falciparum malaria.

  6. Comprehensive study of proteasome inhibitors against Plasmodium falciparum laboratory strains and field isolates from Gabon

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    Kremsner Peter G

    2008-09-01

    Full Text Available Abstract Background The emergence and spread of Plasmodium falciparum resistance to almost all available antimalarial drugs necessitates the search for new chemotherapeutic compounds. The ubiquitin/proteasome system plays a major role in overall protein turnover, especially in fast dividing eukaryotic cells including plasmodia. Previous studies show that the 20S proteasome is expressed and catalytically active in plasmodia and treatment with proteasome inhibitors arrests parasite growth. This is the first comprehensive screening of proteasome inhibitors with different chemical modes of action against laboratory strains of P. falciparum. Subsequently, a selection of inhibitors was tested in field isolates from Lambaréné, Gabon. Methods Epoxomicin, YU101, YU102, MG132, MG115, Z-L3-VS, Ada-Ahx3-L3-VS, lactacystin, bortezomib (Velcade®, gliotoxin, PR11 and PR39 were tested and compared to chloroquine- and artesunate-activities in a standardized in vitro drug susceptibility assay against P. falciparum laboratory strains 3D7, D10 and Dd2. Freshly obtained field isolates from Lambaréné, Gabon, were used to measure the activity of chloroquine, artesunate, epoxomicin, MG132, lactacystin and bortezomib. Parasite growth was detected through histidine-rich protein 2 (HRP2 production. Raw data were fitted by a four-parameter logistic model and individual inhibitory concentrations (50%, 90%, and 99% were calculated. Results Amongst all proteasome inhibitors tested, epoxomicin showed the highest activity in chloroquine-susceptible (IC50: 6.8 nM [3D7], 1.7 nM [D10] and in chloroquine-resistant laboratory strains (IC50: 10.4 nM [Dd2] as well as in field isolates (IC50: 8.5 nM. The comparator drug artesunate was even more active (IC50: 1.0 nM, whereas all strains were chloroquine-resistant (IC50: 113 nM. Conclusion The peptide α',β'-epoxyketone epoxomicin is highly active against P. falciparum regardless the grade of the parasite's chloroquine

  7. A transgenic Plasmodium falciparum NF54 strain that expresses GFP-luciferase throughout the parasite life cycle.

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    Vaughan, Ashley M; Mikolajczak, Sebastian A; Camargo, Nelly; Lakshmanan, Viswanathan; Kennedy, Mark; Lindner, Scott E; Miller, Jessica L; Hume, Jen C C; Kappe, Stefan H I

    2012-12-01

    Plasmodium falciparum is the pathogenic agent of the most lethal of human malarias. Transgenic P. falciparum parasites expressing luciferase have been created to study drug interventions of both asexual and sexual blood stages but luciferase-expressing mosquito stage and liver stage parasites have not been created which has prevented the easy quantification of mosquito stage development (e.g. for transmission blocking interventions) and liver stage development (for interventions that prevent infection). To overcome this obstacle, we have created a transgenic P. falciparum NF54 parasite that expresses a GFP-luciferase transgene throughout the life cycle. Luciferase expression is robust and measurable at all life cycle stages, including midgut oocyst, salivary gland sporozoites and liver stages, where in vivo development is easily measurable using humanized mouse infections in conjunction with an in vivo imaging system. This parasite reporter strain will accelerate testing of interventions against pre-erythrocytic life cycle stages.

  8. Identification and deconvolution of cross-resistance signals from antimalarial compounds using multidrug-resistant Plasmodium falciparum strains.

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    Chugh, Monika; Scheurer, Christian; Sax, Sibylle; Bilsland, Elizabeth; van Schalkwyk, Donelly A; Wicht, Kathryn J; Hofmann, Natalie; Sharma, Anil; Bashyam, Sridevi; Singh, Shivendra; Oliver, Stephen G; Egan, Timothy J; Malhotra, Pawan; Sutherland, Colin J; Beck, Hans-Peter; Wittlin, Sergio; Spangenberg, Thomas; Ding, Xavier C

    2015-02-01

    Plasmodium falciparum, the most deadly agent of malaria, displays a wide variety of resistance mechanisms in the field. The ability of antimalarial compounds in development to overcome these must therefore be carefully evaluated to ensure uncompromised activity against real-life parasites. We report here on the selection and phenotypic as well as genotypic characterization of a panel of sensitive and multidrug-resistant P. falciparum strains that can be used to optimally identify and deconvolute the cross-resistance signals from an extended panel of investigational antimalarials. As a case study, the effectiveness of the selected panel of strains was demonstrated using the 1,2,4-oxadiazole series, a newly identified antimalarial series of compounds with in vitro activity against P. falciparum at nanomolar concentrations. This series of compounds was to be found inactive against several multidrug-resistant strains, and the deconvolution of this signal implicated pfcrt, the genetic determinant of chloroquine resistance. Targeted mode-of-action studies further suggested that this new chemical series might act as falcipain 2 inhibitors, substantiating the suggestion that these compounds have a site of action similar to that of chloroquine but a distinct mode of action. New antimalarials must overcome existing resistance and, ideally, prevent its de novo appearance. The panel of strains reported here, which includes recently collected as well as standard laboratory-adapted field isolates, is able to efficiently detect and precisely characterize cross-resistance and, as such, can contribute to the faster development of new, effective antimalarial drugs.

  9. In vitro evaluation of the antiplasmodial activity of Dendropanax morbifera against chloroquine-sensitive strains of Plasmodium falciparum.

    Science.gov (United States)

    Chung, Ill-Min; Kim, Min-Young; Park, Sun-Dong; Park, Won-Hwan; Moon, Hyung-In

    2009-11-01

    Dendropanax morbifera Leveille (Araliaceae) is well known in Korea traditional medicine for a variety of diseases. The methanol extract of the lower stem parts of D. morbifera was investigated for its activity against chloroquine-sensitive strains of Plasmodium falciparum using the parasite lactate dehydrogenase assay method. Two cycloartane-type glycosides oleifoliosides A (1) and B (2), and dendropanoxide (3), beta-amyrin (4), alpha-amyrin (5) have been isolated from the stem parts of D. morbifera. All five compounds were evaluated for in vitro antiplasmodial activities as well as their cytotoxic potential on SK-OV-3 cancer cell lines. Compounds 2 and 3 showed notable growth inhibitory activity against chloroquine-sensitive strains of Plasmodium falciparum with IC(50) values of 6.2 and 5.3 microm. This compound showed no significant cytotoxicity (IC(50) > 150 microm) evaluated using SK-OV-3 cancer cell lines. This is the first report on the antiplasmodial activity of the compounds from D. morbifera.

  10. Assessment of Plasmodium falciparum resistance to ferroquine (SSR97193 in field isolates and in W2 strain under pressure

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    Pradines Bruno

    2006-02-01

    Full Text Available Abstract Background Ferroquine (FQ, or SSR97193, is a novel antimalarial drug currently in phase I clinical trials. FQ is a unique organometallic compound designed to overcome the chloroquine (CQ resistance problem. FQ revealed to be equally active on CQ-sensitive and CQ-resistant Plasmodium falciparum laboratory strains and field isolates. FQ is also curative on rodent malaria parasites. As FQ will be tested in patients, the potential for resistance to this drug was evaluated. Methods The relationship between CQ-resistant transporter gene genotype and susceptibility to FQ were studied in 33 Cambodian P. falciparum field isolates previously studied for their in vitro response to CQ. In parallel, the ability of the CQ-resistant strain W2, to become resistant to FQ under drug pressure was assessed. Results The IC50 values for FQ in field isolates were found to be unrelated to mutations occurring in the P. falciparum chloroquine resistance transporter (PfCRT or to the level of expression of the corresponding mRNA. In vitro, under a drug pressure of 100 nM of FQ, transient survival was observed in only one of two experiments. Conclusion Field isolates studies and experimental drug pressure experiments showed that FQ overcomes CQ resistance, which reinforces the potential of this compound as a new antimalarial drug.

  11. A barcode of organellar genome polymorphisms identifies the geographic origin of Plasmodium falciparum strains

    KAUST Repository

    Preston, Mark D.

    2014-06-13

    Malaria is a major public health problem that is actively being addressed in a global eradication campaign. Increased population mobility through international air travel has elevated the risk of re-introducing parasites to elimination areas and dispersing drug-resistant parasites to new regions. A simple genetic marker that quickly and accurately identifies the geographic origin of infections would be a valuable public health tool for locating the source of imported outbreaks. Here we analyse the mitochondrion and apicoplast genomes of 711 Plasmodium falciparum isolates from 14 countries, and find evidence that they are non-recombining and co-inherited. The high degree of linkage produces a panel of relatively few single-nucleotide polymorphisms (SNPs) that is geographically informative. We design a 23-SNP barcode that is highly predictive (?92%) and easily adapted to aid case management in the field and survey parasite migration worldwide. 2014 Macmillan Publishers Limited. All rights reserved.

  12. 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

  13. A sequence in subdomain 2 of DBL1α of Plasmodium falciparum erythrocyte membrane protein 1 induces strain transcending antibodies.

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    Karin Blomqvist

    Full Text Available Immunity to severe malaria is the first level of immunity acquired to Plasmodium falciparum. Antibodies to the variant antigen PfEMP1 (P. falciparum erythrocyte membrane protein 1 present at the surface of the parasitized red blood cell (pRBC confer protection by blocking microvascular sequestration. Here we have generated antibodies to peptide sequences of subdomain 2 of PfEMP1-DBL1α previously identified to be associated with severe or mild malaria. A set of sera generated to the amino acid sequence KLQTLTLHQVREYWWALNRKEVWKA, containing the motif ALNRKE, stained the live pRBC. 50% of parasites tested (7/14 were positive both in flow cytometry and immunofluorescence assays with live pRBCs including both laboratory strains and in vitro adapted clinical isolates. Antibodies that reacted selectively with the sequence REYWWALNRKEVWKA in a 15-mer peptide array of DBL1α-domains were also found to react with the pRBC surface. By utilizing a peptide array to map the binding properties of the elicited anti-DBL1α antibodies, the amino acids WxxNRx were found essential for antibody binding. Complementary experiments using 135 degenerate RDSM peptide sequences obtained from 93 Ugandan patient-isolates showed that antibody binding occurred when the amino acids WxLNRKE/D were present in the peptide. The data suggests that the ALNRKE sequence motif, associated with severe malaria, induces strain-transcending antibodies that react with the pRBC surface.

  14. Whole transcriptome expression analysis and comparison of two different strains of Plasmodium falciparum using RNA-Seq

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    Hiasindh Ashmi Antony

    2016-06-01

    Full Text Available The emergence and distribution of drug resistance in malaria are serious public health concerns in tropical and subtropical regions of the world. However, the molecular mechanism of drug resistance remains unclear. In the present study, we performed a high-throughput RNA-Seq to identify and characterize the differentially expressed genes between the chloroquine (CQ sensitive (3D7 and resistant (Dd2 strains of Plasmodium falciparum. The parasite cells were cultured in the presence and absence of CQ by in vitro method. Total RNA was isolated from the harvested parasite cells using TRIzol, and RNA-Seq was conducted using an Illumina HiSeq 2500 sequencing platform with paired-end reads and annotated using Tophat. The transcriptome analysis of P. falciparum revealed the expression of ~5000 genes, in which ~60% of the genes have unknown function. Cuffdiff program was used to identify the differentially expressed genes between the CQ-sensitive and resistant strains. Here, we furnish a detailed description of the experimental design, procedure, and analysis of the transcriptome sequencing data, that have been deposited in the National Center for Biotechnology Information (accession nos. PRJNA308455 and GSE77499.

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

    African Journals Online (AJOL)

    Plasmodium falciparum malaria associated with ABO blood phenotypes and ... out to investigate the relationship between blood group types and P. falciparum ... of long lasting treated (LLT) mosquito bed nets and the prevalence of infection.

  16. Competition between Plasmodium falciparum strains in clinical infections during in vitro culture adaptation.

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    Chen, Kexuan; Sun, Ling; Lin, Yingxue; Fan, Qi; Zhao, Zhenjun; Hao, Mingming; Feng, Guohua; Wu, Yanrui; Cui, Liwang; Yang, Zhaoqing

    2014-06-01

    We evaluated the dynamics of parasite populations during in vitro culture adaptation in 15 mixed Plasmodium falciparum infections, which were collected from a hypoendemic area near the China-Myanmar border. Allele types at the msp1 block 2 in the initial clinical samples and during subsequent culture were quantified weekly using a quantitative PCR method. All mixed infections carried two allele types based on the msp1 genotyping result. We also genotyped several polymorphic sites in the dhfr, dhps and mdr1 genes on day 0 and day 28, which showed that most of the common sites analyzed were monomorphic. Two of the three clinical samples mixed at dhps 581 remained stable while one changed to wild-type during the culture. During in vitro culture, we observed a gradual loss of parasite populations with 10 of the 15 mixed infections becoming monoclonal by day 28 based on the msp1 allele type. In most cases, the more abundant msp1 allele types in the clinical blood samples at the beginning of culture became the sole or predominant allele types on day 28. These results suggest that some parasites may have growth advantages and the loss of parasite populations during culture adaptation of mixed infections may lead to biased results when comparing the phenotypes such as drug sensitivity of the culture-adapted parasites.

  17. Tetany with Plasmodium falciparum infection.

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    Singh, P S; Singh, Neha

    2012-07-01

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

  18. In vitro antiplasmodial effiacy of mangrove plant, Ipomoea pes-caprae against Plasmodium falciparum (3D7 strain

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    Veera Venkata Satish Pothula

    2015-12-01

    Full Text Available Objective: To evaluate the antiplasmodial activity of mangrove plant, Ipomoea pes-caprae (I. pes-caprae (leaves, stems, flowers and roots against chloroquine-sensitive Plasmodium falciparum (3D7 strain (P. falciparum and cytotoxicity against brine shrimp larvae and THP-1 cell line. Methods: The plants (I. pes-caprae were collected from Machilipatnam mangrove forest (latitude 16°17′ N and longitude 81 °13′ E of Krishna District, Andhra Pradesh, India. Crude extracts from dried leaves, stems, flowers and roots of I. pes-caprae were prepared through Soxhlet extraction using methanol, chloroform, hexane, ethyl acetate and aqueous sequentially. These extracts were tested in vitro against P. falciparum (3D7 strain adopted in laboratory. The crude extracts were also tested for their cytotoxicity against brine shrimp larvae and THP-1 cell line. The phytochemical screenings were also conducted with standard methods. As the part of the study, the extracts were checked for any chemical injury to erythrocytes. Results: Out of these extracts, methanolic and aqueous extracts of all plant parts and chloroform extract of stems were active, and the ethyl acetate extracts were weekly active against P. falciparum. The extracts of chloroform (except stems and hexane were inactive. Amongst these extracts, the methanolic extract of root showed excellent antimalarial activity with the IC 50 value of 15.00 µg/mL. Cytotoxic evaluation revealed that methanolic, aqueous and ethyl acetate extracts were slightly cytotoxic whereas chloroform and hexane extracts were more toxic against brine shrimp. All extracts were non-toxic to THP-1 cells. The chemical injury to erythrocytes was also evaluated and it did not show any morphological changes in erythrocytes due to the effect of plant extracts of I. pes-caprae after 48 h of incubation. The phytochemical screening of the extracts revealed the presence of alkaloids, triterpenes, flavonoids, tannins, coumarins

  19. Telomeric Heterochromatin in Plasmodium falciparum

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    Rosaura Hernandez-Rivas

    2010-01-01

    Full Text Available Until very recently, little was known about the chromatin structure of the telomeres and subtelomeric regions in Plasmodium falciparum. In yeast and Drosophila melanogaster, chromatin structure has long been known to be an important aspect in the regulation and functioning of these regions. Telomeres and subtelomeric regions are enriched in epigenetic marks that are specific to heterochromatin, such as methylation of lysine 9 of histone H3 and lysine 20 of histone H4. In P. falciparum, histone modifications and the presence of both the heterochromatin “writing” (PfSir2, PKMT and “reading” (PfHP1 machinery at telomeric and subtelomeric regions indicate that these regions are likely to have heterochromatic structure that is epigenetically regulated. This structure may be important for telomere functions such as the silencing of the var gene family implicated in the cytoadherence and antigenic variation of these parasites.

  20. Molecular characterization and phylogenetic analysis of Plasmodium vivax, Plasmodium falciparum, Plasmodium ovale, Plasmodium malariae and Plasmodium cynomolgi

    National Research Council Canada - National Science Library

    Chatterjee, Soumendranath; Mukhopadhyay, Priyanka; Bandyopadhyay, Raktima; Dhal, Paltu; Biswal, Debraj; Bandyopadhyay, Prabir Kumar

    18S ribosomal RNA gene sequences of different species of Plasmodium were aligned and analyzed to determine the molecular diversity among different species of Plasmodium. AT content of P. cynomolgi, P. ovale, P. falciparum, P. vivax and P...

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

    Science.gov (United States)

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

    2015-01-01

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

  2. Amplification of a Gene Related to Mammalian mdr Genes in Drug-Resistant Plasmodium falciparum

    Science.gov (United States)

    Wilson, Craig M.; Serrano, Adelfa E.; Wasley, Annemarie; Bogenschutz, Michael P.; Shankar, Anuraj H.; Wirth, Dyann F.

    1989-06-01

    The malaria parasite Plasmodium falciparum contains at least two genes related to the mammalian multiple drug resistance genes, and at least one of the P. falciparum genes is expressed at a higher level and is present in higher copy number in a strain that is resistant to multiple drugs than in a strain that is sensitive to the drugs.

  3. Plasmodium falciparum Malaria, Southern Algeria, 2007

    OpenAIRE

    Boubidi, Saïd C; 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.

  4. Congenital Plasmodium falciparum Malaria in Washington, DC.

    Science.gov (United States)

    Del Castillo, Melissa; Szymanski, Ann Marie; Slovin, Ariella; Wong, Edward C C; DeBiasi, Roberta L

    2017-01-11

    Congenital malaria is rare in the United States, but is an important diagnosis to consider when evaluating febrile infants. Herein, we describe a case of congenital Plasmodium falciparum malaria in a 2-week-old infant born in the United States to a mother who had emigrated from Nigeria 3 months before delivery. © The American Society of Tropical Medicine and Hygiene.

  5. 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

  6. Plasmodium falciparum Malaria, Southern Algeria, 2007

    OpenAIRE

    Boubidi, Saïd C; 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.

  7. Survival strategies of the malarial parasite Plasmodium falciparum

    OpenAIRE

    Ramya, TNC; Surolia, Namita; Surolia, Avadhesha

    2002-01-01

    Plasmodium falciparum, the protozoan parasite causing falciparum malaria, is undoubtedly highly versatile when it comes to survival and defence strategies. Strategies adopted by the asexual blood stages of Plasmodium range from unique pathways of nutrient uptake to immune evasion strategies and multiple drug resistance. Studying the survival strategies of Plasmodium could help us envisage strategies of tackling one of the worst scourges of mankind.

  8. Guillain-Barré syndrome in Plasmodium falciparum malaria.

    OpenAIRE

    Wijesundere, A.

    1992-01-01

    A patient with Plasmodium falciparum malaria developed peripheral neuropathy. Clinical, cerebro-spinal fluid examination and nerve conduction studies confirmed Guillain-Barré syndrome, not previously reported in P. falciparum malaria.

  9. Effects of age, hemoglobin type and parasite strain on IgG recognition of Plasmodium falciparum-infected erythrocytes in Malian children.

    Directory of Open Access Journals (Sweden)

    Amir E Zeituni

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

  10. The antiplasmodium effects of a traditional South American remedy: Zanthoxylum chiloperone var. angustifolium against chloroquine resistant and chloroquine sensitive strains of Plasmodium falciparum

    Directory of Open Access Journals (Sweden)

    Gerardo Cebrian-Torrejon

    2011-08-01

    Full Text Available Zanthoxylum chiloperone var. angustifolium Engl., Rutaceae, is used in traditional medicine to treat fungal and protozoal infections in the central area of South America. Considering the increasing resistance of Plasmodium falciparum in malarial ridden areas, we explored the anti-plasmodial effects of three compounds isolated from Z. chiloperone. The pyranocoumarin transavicennol and the canthinone alkaloids, canthin-6-one and 5-methoxycanthin-6-one, were found to have IC50 on chloroquine/mefloquine resistant and sensitive strains of P. falciparum of 0.5-2.7, 2.0-5.3 and 5.1-10.4 ƒÊg/mL, respectively. Moreover, the formation of heme adducts by these compounds is described by a novel alternative method based on MS-CID methods. The alkylamide sanshool was also identified, for first time in this plant, in the dichloromethanic and ethanolic extracts and the extracts were found to be notably non-toxic and displayed good anti-plasmodial effects.

  11. Exploring the folate pathway in Plasmodium falciparum

    OpenAIRE

    Hyde, John E.

    2005-01-01

    As in centuries past, the main weapon against human malaria infections continues to be intervention with drugs, despite the widespread and increasing frequency of parasite populations that are resistant to one or more of the available compounds. This is a particular problem with the lethal species of parasite, Plasmodium falciparum, which claims some two million lives per year as well as causing enormous social and economic problems. Amongst the antimalarial drugs currently in clinical use, t...

  12. Genetic diversity of Plasmodium vivax and Plasmodium falciparum in Honduras

    Directory of Open Access Journals (Sweden)

    Lopez Ana

    2012-11-01

    Full Text Available Abstract Background Understanding the population structure of Plasmodium species through genetic diversity studies can assist in the design of more effective malaria control strategies, particularly in vaccine development. Central America is an area where malaria is a public health problem, but little is known about the genetic diversity of the parasite’s circulating species. This study aimed to investigate the allelic frequency and molecular diversity of five surface antigens in field isolates from Honduras. Methods Five molecular markers were analysed to determine the genotypes of Plasmodium vivax and Plasmodium falciparum from endemic areas in Honduras. Genetic diversity of ama-1, msp-1 and csp was investigated for P. vivax, and msp-1 and msp-2 for P. falciparum. Allelic frequencies were calculated and sequence analysis performed. Results and conclusion A high genetic diversity was observed within Plasmodium isolates from Honduras. A different number of genotypes were elucidated: 41 (n = 77 for pvama-1; 23 (n = 84 for pvcsp; and 23 (n = 35 for pfmsp-1. Pvcsp sequences showed VK210 as the only subtype present in Honduran isolates. Pvmsp-1 (F2 was the most polymorphic marker for P. vivax isolates while pvama-1 was least variable. All three allelic families described for pfmsp-1 (n = 30 block 2 (K1, MAD20, and RO33, and both allelic families described for the central domain of pfmsp-2 (n = 11 (3D7 and FC27 were detected. However, K1 and 3D7 allelic families were predominant. All markers were randomly distributed across the country and no geographic correlation was found. To date, this is the most complete report on molecular characterization of P. vivax and P. falciparum field isolates in Honduras with regards to genetic diversity. These results indicate that P. vivax and P. falciparum parasite populations are highly diverse in Honduras despite the low level of transmission.

  13. [Research Progress on Artemisinin Resistance in Plasmodium falciparum].

    Science.gov (United States)

    Zhang, Yi-long; Pan, Wei-qing

    2015-12-01

    Artemisinin (ART) is a novel and effective antimalarial drug discovered in China. As recommended by the World Health Organization, the ART-based combination therapies (ACTs) have become the first-line drugs for the treatment of falciparum malaria. ART and its derivatives have contributed greatly to the effective control of malaria globally, leading to yearly decrease of malaria morbidity and mortality. However, there have recently been several reports on the resistance of Plasmodium falciparum to ART in Southeast Asia. This is deemed a serious threat to the global malaria control programs. In this paper, we reviewed recent research progress on ART resistance to P. falciparum, including new tools for resistance measurement, resistance-associated molecular markers, and the origin and spread of the ART-resistant parasite strains.

  14. 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.

  15. A nuclear targeting system in Plasmodium falciparum

    Directory of Open Access Journals (Sweden)

    Kochakarn Theerarat

    2010-05-01

    Full Text Available Abstract Background The distinct differences in gene control mechanisms acting in the nucleus between Plasmodium falciparum and the human host could lead to new potential drug targets for anti-malarial development. New molecular toolkits are required for dissecting molecular machineries in the P. falciparum nucleus. One valuable tool commonly used in model organisms is protein targeting to specific sub-cellular locations. Targeting proteins to specified locations allows labeling of organelles for microscopy, or testing of how the protein of interest modulates organelle function. In recent years, this approach has been developed for various malaria organelles, such as the mitochondrion and the apicoplast. A tool for targeting a protein of choice to the P. falciparum nucleus using an exogenous nuclear localization sequence is reported here. Methods To develop a nuclear targeting system, a putative nuclear localization sequence was fused with green fluorescent protein (GFP. The nuclear localization sequence from the yeast transcription factor Gal4 was chosen because of its well-defined nuclear localization signal. A series of truncated Gal4 constructs was also created to narrow down the nuclear localization sequence necessary for P. falciparum nuclear import. Transfected parasites were analysed by fluorescent and laser-scanning confocal microscopy. Results The nuclear localization sequence of Gal4 is functional in P. falciparum. It effectively transported GFP into the nucleus, and the first 74 amino acid residues were sufficient for nuclear localization. Conclusions The Gal4 fusion technique enables specific transport of a protein of choice into the P. falciparum nucleus, and thus provides a tool for labeling nuclei without using DNA-staining dyes. The finding also indicates similarities between the nuclear transport mechanisms of yeast and P. falciparum. Since the nuclear transport system has been thoroughly studied in yeast, this could give clues

  16. A Redox-Active Fluorescent pH Indicator for Detecting Plasmodium falciparum Strains with Reduced Responsiveness to Quinoline Antimalarial Drugs.

    Science.gov (United States)

    Jida, Mouhamad; Sanchez, Cecilia P; Urgin, Karène; Ehrhardt, Katharina; Mounien, Saravanan; Geyer, Aurelia; Elhabiri, Mourad; Lanzer, Michael; Davioud-Charvet, Elisabeth

    2017-02-10

    Mutational changes in the Plasmodium falciparum chloroquine resistance transporter (PfCRT) have been associated with differential responses to a wide spectrum of biologically active compounds including current and former quinoline and quinoline-like antimalarial drugs. PfCRT confers altered drug responsiveness by acting as a transport system, expelling drugs from the parasite's digestive vacuole where these drugs exert, at least part of, their antiplasmodial activity. To preserve the efficacy of these invaluable drugs, novel functional tools are required for epidemiological surveys of parasite strains carrying mutant PfCRT variants and for drug development programs aimed at inhibiting or circumventing the action of PfCRT. Here we report the synthesis and characterization of a pH-sensitive fluorescent chloroquine analogue consisting of 7-chloro-N-{2-[(propan-2-yl)amino]ethyl}quinolin-4-amine functionalized with the fluorochrome 7-nitrobenzofurazan (NBD) (henceforth termed Fluo-CQ). In the parasite, Fluo-CQ accumulates in the digestive vacuole, giving rise to a strong fluorescence signal but only in parasites carrying the wild type PfCRT. In parasites carrying the mutant PfCRT, Fluo-CQ does not accumulate. The differential handling of the fluorescent probe, combined with live cell imaging, provides a diagnostic tool for quick detection of those P. falciparum strains that carry a PfCRT variant associated with altered responsiveness to quinoline and quinoline-like antimalarial drugs. In contrast to the accumulation studies, chloroquine (CQ)-resistant parasites were observed cross-resistant to Fluo-CQ when the chemical probe was tested in various CQ-sensitive and -resistant parasite strains. NBD derivatives were found to act as redox cyclers of two essential targets, using a coupled assay based on methemoglobin and the NADPH-dependent glutathione reductase (GRs) from P. falciparum. This redox activity is proposed to contribute to the dual action of Fluo-CQ on redox

  17. Complement evasion by Plasmodium falciparum

    OpenAIRE

    Holopainen, Saila

    2008-01-01

    Patologian oppiaine Malaria remains one of the major health problems in many tropical countries, especially in sub-Saharan Africa. Among the most characteristic features of the malaria pathogens, protozoan parasites of the genus Plasmodium, is their ability to evade the immune defences of the host for extended periods of time. The complement system (C) is an essential part of the innate system in the first line of defense. It consists of over 30 soluble or membrane-bound components. C...

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

    OpenAIRE

    Schunk, Mirjam; Kumma, Wondimagegn P.; Barreto Miranda, Isabel; Maha E. Osman; Roewer, Susanne; Alano, Abraham; Loescher, Thomas; Bienzle, Ulrich; Mockenhaupt, Frank P

    2006-01-01

    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 assesse...

  19. Driving mosquito refractoriness to Plasmodium falciparum with engineered symbiotic bacteria.

    Science.gov (United States)

    Wang, Sibao; Dos-Santos, André L A; Huang, Wei; Liu, Kun Connie; Oshaghi, Mohammad Ali; Wei, Ge; Agre, Peter; Jacobs-Lorena, Marcelo

    2017-09-29

    The huge burden of malaria in developing countries urgently demands the development of novel approaches to fight this deadly disease. Although engineered symbiotic bacteria have been shown to render mosquitoes resistant to the parasite, the challenge remains to effectively introduce such bacteria into mosquito populations. We describe a Serratia bacterium strain (AS1) isolated from Anopheles ovaries that stably colonizes the mosquito midgut, female ovaries, and male accessory glands and spreads rapidly throughout mosquito populations. Serratia AS1 was genetically engineered for secretion of anti-Plasmodium effector proteins, and the recombinant strains inhibit development of Plasmodium falciparum in mosquitoes. Copyright © 2017 The Authors, some rights reserved; exclusive licensee American Association for the Advancement of Science. No claim to original U.S. Government Works.

  20. Desferrioxamine suppresses Plasmodium falciparum in Aotus monkeys.

    Science.gov (United States)

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

    1987-02-01

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

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

    OpenAIRE

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

    2009-01-01

    Polymorphisms in the Plasmodium falciparum crt (Pfcrt), Pfmdr1, and Pfmrp genes were not significantly associated with quinine (QN) 50% inhibitory concentrations (IC50s) in 23 strains of Plasmodium falciparum. An increased number of DNNND repeats in Pfnhe-1 microsatellite ms4760 was associated with an increased IC50 of QN (P = 0.0007). Strains with only one DNNND repeat were more susceptible to QN (mean IC50 of 154 nM). Strains with two DNNND repeats had intermediate susceptibility to QN (mea...

  2. The novel oxygenated chalcone, 2,4-dimethoxy-4'-butoxychalcone, exhibits potent activity against human malaria parasite Plasmodium falciparum in vitro and rodent parasites Plasmodium berghei and Plasmodium yoelii in vivo

    DEFF Research Database (Denmark)

    Chen, M; Brøgger Christensen, S; Zhai, L

    1997-01-01

    growth of both a chloroquine-susceptible (3D7) and a chloroquine-resistant (Dd2) strain of Plasmodium falciparum in a [3H]hypoxanthine uptake assay. The in vivo activity of 2,4mbc was tested in mice infected with Plasmodium berghei or Plasmodium yoelii and in rats infected with P. berghei. 2,4mbc...

  3. Antimalarial Benzoxaboroles Target Plasmodium falciparum Leucyl-tRNA Synthetase.

    Science.gov (United States)

    Sonoiki, Ebere; Palencia, Andres; Guo, Denghui; Ahyong, Vida; Dong, Chen; Li, Xianfeng; Hernandez, Vincent S; Zhang, Yong-Kang; Choi, Wai; Gut, Jiri; Legac, Jennifer; Cooper, Roland; Alley, M R K; Freund, Yvonne R; DeRisi, Joseph; Cusack, Stephen; Rosenthal, Philip J

    2016-08-01

    There is a need for new antimalarials, ideally with novel mechanisms of action. Benzoxaboroles have been shown to be active against bacteria, fungi, and trypanosomes. Therefore, we investigated the antimalarial activity and mechanism of action of 3-aminomethyl benzoxaboroles against Plasmodium falciparum Two 3-aminomethyl compounds, AN6426 and AN8432, demonstrated good potency against cultured multidrug-resistant (W2 strain) P. falciparum (50% inhibitory concentration [IC50] of 310 nM and 490 nM, respectively) and efficacy against murine Plasmodium berghei infection when administered orally once daily for 4 days (90% effective dose [ED90], 7.4 and 16.2 mg/kg of body weight, respectively). To characterize mechanisms of action, we selected parasites with decreased drug sensitivity by culturing with stepwise increases in concentration of AN6426. Resistant clones were characterized by whole-genome sequencing. Three generations of resistant parasites had polymorphisms in the predicted editing domain of the gene encoding a P. falciparum leucyl-tRNA synthetase (LeuRS; PF3D7_0622800) and in another gene (PF3D7_1218100), which encodes a protein of unknown function. Solution of the structure of the P. falciparum LeuRS editing domain suggested key roles for mutated residues in LeuRS editing. Short incubations with AN6426 and AN8432, unlike artemisinin, caused dose-dependent inhibition of [(14)C]leucine incorporation by cultured wild-type, but not resistant, parasites. The growth of resistant, but not wild-type, parasites was impaired in the presence of the unnatural amino acid norvaline, consistent with a loss of LeuRS editing activity in resistant parasites. In summary, the benzoxaboroles AN6426 and AN8432 offer effective antimalarial activity and act, at least in part, against a novel target, the editing domain of P. falciparum LeuRS.

  4. Pharmacophore model for pentamidine analogs active against Plasmodium falciparum.

    Science.gov (United States)

    Athri, Prashanth; Wenzler, Tanja; Tidwell, Richard; Bakunova, Svetlana M; Wilson, W David

    2010-12-01

    Pentamidine and its analogs constitute a class of compounds that are known to be active against Plasmodium falciparum, which causes the most dangerous malarial infection. Malaria is a widespread disease known to affect hundreds of millions of people and presents a perceivable threat of spreading. Hence, there is a need for well-defined scaffolds that lead to new, effective treatment. Here we present a pentamidine-based pharmacophore constructed using GALAHAD that would aid targeted synthesis of leads with enhanced properties, as well as the development of lead scaffolds. The study was supported by high-quality biological in vitro data of 22 compounds against the P. falciparum strains NF54 and K1. The model established reveals the importance of hydrophobic phenyl rings with polar oxygen and amidine substituents and the hydrophobic linking chain for the activity against malaria.

  5. International population movements and regional Plasmodium falciparum malaria elimination strategies

    National Research Council Canada - National Science Library

    Andrew J. Tatem; David L. Smith; Susan Hanson

    2010-01-01

    ... to areas targeted for elimination. Here, census-based migration data were analyzed with network analysis tools, Plasmodium falciparum malaria transmission maps, and global population databases to map globally communities of countries...

  6. 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...

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

    NARCIS (Netherlands)

    Schats, R.; Bijker, E.M.; Gemert, G.J.A. van; Graumans, W.; Vegte-Bolmer, M. van de; Lieshout, L. van; Haks, M.C.; Hermsen, C.C.; Scholzen, A.; Visser, L.G.; Sauerwein, R.W.

    2015-01-01

    BACKGROUND: 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),

  8. Mosquito Vectors and the Globalization of Plasmodium falciparum Malaria.

    Science.gov (United States)

    Molina-Cruz, Alvaro; Zilversmit, Martine M; Neafsey, Daniel E; Hartl, Daniel L; Barillas-Mury, Carolina

    2016-11-23

    Plasmodium falciparum malaria remains a devastating public health problem. Recent discoveries have shed light on the origin and evolution of Plasmodium parasites and their interactions with their vertebrate and mosquito hosts. P. falciparum malaria originated in Africa from a single horizontal transfer between an infected gorilla and a human, and became global as the result of human migration. Today, P. falciparum malaria is transmitted worldwide by more than 70 different anopheline mosquito species. Recent studies indicate that the mosquito immune system can be a barrier to malaria transmission and that the P. falciparum Pfs47 gene allows the parasite to evade mosquito immune detection. Here, we review the origin and globalization of P. falciparum and integrate this history with analysis of the biology, evolution, and dispersal of the main mosquito vectors. This new perspective broadens our understanding of P. falciparum population structure and the dispersal of important parasite genetic traits.

  9. Acute kidney injury in imported Plasmodium falciparum malaria

    NARCIS (Netherlands)

    L.C. Koopmans (Liese); M.E. van Wolfswinkel (Marlies); D.A. Hesselink (Dennis); E.J. Hoorn (Ewout); R. Koelewijn (Rob); J.J. van Hellemond (Jaap); P.J.J. van Genderen (Perry)

    2015-01-01

    textabstractBackground: Acute kidney injury (AKI) is a known complication of malaria, and is reported to occur in up to 40 % of adult patients with a severe Plasmodium falciparum infection in endemic regions. To gain insight in the incidence and risk factors of AKI in imported P. falciparum malaria,

  10. Acute kidney injury in imported Plasmodium falciparum malaria

    NARCIS (Netherlands)

    L.C. Koopmans, L.C. (Liese); M.E. van Wolfswinkel (Marlies); D.A. Hesselink (Dennis); E.J. Hoorn (Ewout); R. Koelewijn (Rob); J.J. van Hellemond (Jaap); P.J. van Genderen (P.)

    2015-01-01

    textabstractBackground: Acute kidney injury (AKI) is a known complication of malaria, and is reported to occur in up to 40 % of adult patients with a severe Plasmodium falciparum infection in endemic regions. To gain insight in the incidence and risk factors of AKI in imported P. falciparum malaria,

  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. Molecular mechanisms and biological importance of Plasmodium falciparum erythrocyte rosetting

    Directory of Open Access Journals (Sweden)

    Mats Wahlgren

    1992-01-01

    Full Text Available Rosetting, i.e. the spontaneous binding of uninfected to malaria infected erythrocytes and endothelial cytoadherence may hinder the blood flow and lead to serve Plasmodium falciparum malaria. Falciparum isolates obtained from unconscious patients all form rosettes and/or express a significantly higher man rosetting rate than isolates from patients with uncomplicated malaria. Furthermore, sera of patients with cerebral malaria are devoid of anti-rosetting activity while sera from patients with mild disease carry high levels of anti-rosetting antibodies. The presence of anti-rosetting antibodies also seems important for the efficient interaction of rosetting infected rbc and leucocytes. Two parasite derived rosetting ligands of Mr 22k and Mr28K named "rosettins, have been found on the surface of rosetting infected erythrocytes. CD36 has in at least some strains of parasites been found to function as a rosetting receptor on the uninfectederythrocyte. Heparin disrupts rosettes of P. falciparum in vitro and inhibits the sequestration of rosetting cells ex vivo. In conclusion, rosetting seems a crucial factor in the development of cerebral malaria and treatment of patients with anti-rosetting substances might become an effectivew adjunct in the treatment of severe malaria.

  13. The role of Plasmodium falciparum food vacuole plasmepsins.

    Science.gov (United States)

    Liu, Jun; Gluzman, Ilya Y; Drew, Mark E; Goldberg, Daniel E

    2005-01-14

    Plasmepsins (PMs) are thought to have an important function in hemoglobin degradation in the malarial parasite Plasmodium falciparum and have generated interest as antimalarial drug targets. Four paralogous plasmepsins reside in the food vacuole of P. falciparum. Targeted gene disruption by double crossover homologous recombination has been employed to study food vacuole plasmepsin function in cultured parasites. Parasite clones with deletions in each of the individual PM I, PM II, and HAP genes as well as clones with a double PM IV/PM I disruption have been generated. All of these clones lack the corresponding PMs, are viable, and appear morphologically normal. PM II and PM IV/I disruptions have longer doubling times than the 3D7 parental line in rich RPMI medium. This appears to be because of a decreased level of productive progeny rather than an increased cell cycle time. In amino acid-limited medium, all four knockouts exhibit slower growth than the parental strain. Compared with 3D7, knock-out clone sensitivity to aspartic and cysteine protease inhibitors is changed minimally. These results suggest substantial functional redundancy and have important implications for the design of antimalarial drugs. The slow growth phenotype may explain why P. falciparum has maintained four plasmepsin genes with overlapping functions.

  14. Combating multidrug-resistant Plasmodium falciparum malaria.

    Science.gov (United States)

    Thu, Aung Myint; Phyo, Aung Pyae; Landier, Jordi; Parker, Daniel M; Nosten, François H

    2017-08-01

    Over the past 50 years, Plasmodium falciparum has developed resistance against all antimalarial drugs used against it: chloroquine, sulphadoxine-pyrimethamine, quinine, piperaquine and mefloquine. More recently, resistance to the artemisinin derivatives and the resulting failure of artemisinin-based combination therapy (ACT) are threatening all major gains made in malaria control. Each time resistance has developed progressively, with delayed clearance of parasites first emerging only in a few regions, increasing in prevalence and geographic range, and then ultimately resulting in the complete failure of that antimalarial. Drawing from this repeated historical chain of events, this article presents context-specific approaches for combating drug-resistant P. falciparum malaria. The approaches begin with a context of drug-sensitive parasites and focus on the prevention of the emergence of drug resistance. Next, the approaches address a scenario in which resistance has emerged and is increasing in prevalence and geographic extent, with interventions focused on disrupting transmission through vector control, early diagnosis and treatment, and the use of new combination therapies. Elimination is also presented as an approach for addressing the imminent failure of all available antimalarials. The final drug resistance context presented is one in which all available antimalarials have failed; leaving only personal protection and the use of new antimalarials (or new combinations of antimalarials) as a viable strategy for dealing with complete resistance. All effective strategies and contexts require a multipronged, holistic approach. © 2017 The Authors. The FEBS Journal published by John Wiley & Sons Ltd on behalf of Federation of European Biochemical Societies.

  15. The dynamics of natural Plasmodium falciparum infections.

    Directory of Open Access Journals (Sweden)

    Ingrid Felger

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

  16. A genetic analysis of Plasmodium falciparum RNA polymerase II subunits in yeast.

    Science.gov (United States)

    Hazoume, Adonis; Naderi, Kambiz; Candolfi, Ermanno; Kedinger, Claude; Chatton, Bruno; Vigneron, Marc

    2011-04-01

    RNA polymerase II is an essential nuclear multi subunit enzyme that transcribes nearly the whole genome. Its inhibition by the alpha-amanitin toxin leads to cell death. The enzyme of Plasmodium falciparum remains poorly characterized. Using a complementation assay in yeast as a genetic test, we demonstrate that five Plasmodium putative RNA polymerase subunits are indeed functional in vivo. The active site of this enzyme is built from the two largest subunits. Using site directed mutagenesis we were able to modify the active site of the yeast RNA polymerase II so as to introduce Plasmodium or human structural motifs. The resulting strains allow the screening of chemical libraries for potential specific inhibitors.

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

    Directory of Open Access Journals (Sweden)

    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.

  18. Refrigeration provides a simple means to synchronize in vitro cultures of Plasmodium falciparum.

    Science.gov (United States)

    Yuan, Lili; Hao, Mingming; Wu, Lanou; Zhao, Zhen; Rosenthal, Benjamin M; Li, Xiaomei; He, Yongshu; Sun, Ling; Feng, Guohua; Xiang, Zheng; Cui, Liwang; Yang, Zhaoqing

    2014-05-01

    Plasmodium falciparum is usually asynchronous during in vitro culture. Highly synchronized cultures of P. falciparum are routinely used in malaria research. Here, we describe a simple synchronization procedure for P. falciparum asexual erythrocytic culture, which involves storage at 4°C for 8-24 h followed by routine culture. When cultures with 27-60% of ring stage were synchronized using this procedure, 70-93% ring stages were obtained after 48 h of culture and relative growth synchrony remained for at least two erythrocytic cycles. To test the suitability of this procedure for subsequent work, drug sensitivity assays were performed using four laboratory strains and four freshly adapted clinical P. falciparum isolates. Parasites synchronized by sorbitol treatment or refrigeration showed similar dose-response curves and comparable IC50 values to four antimalarial drugs. The refrigeration synchronization method is simple, inexpensive, time-saving, and should be especially useful when large numbers of P. falciparum culture are handled.

  19. Exploring the folate pathway in Plasmodium falciparum.

    Science.gov (United States)

    Hyde, John E

    2005-06-01

    As in centuries past, the main weapon against human malaria infections continues to be intervention with drugs, despite the widespread and increasing frequency of parasite populations that are resistant to one or more of the available compounds. This is a particular problem with the lethal species of parasite, Plasmodium falciparum, which claims some two million lives per year as well as causing enormous social and economic problems. Amongst the antimalarial drugs currently in clinical use, the antifolates have the best defined molecular targets, namely the enzymes dihydrofolate reductase (DHFR) and dihydropteroate synthase (DHPS), which function in the folate metabolic pathway. The products of this pathway, reduced folate cofactors, are essential for DNA synthesis and the metabolism of certain amino acids. Moreover, their formation and interconversions involve a number of other enzymes that have not as yet been exploited as drug targets. Antifolates are of major importance as they currently represent the only inexpensive regime for combating chloroquine-resistant malaria, and are now first-line drugs in a number of African countries. Aspects of our understanding of this pathway and antifolate drug resistance are reviewed here, with a particular emphasis on approaches to analysing the details of, and balance between, folate biosynthesis by the parasite and salvage of pre-formed folate from exogenous sources.

  20. New synchronization method for Plasmodium falciparum

    Directory of Open Access Journals (Sweden)

    Mwangi Jonathan M

    2010-06-01

    Full Text Available Abstract Background Plasmodium falciparum is usually asynchronous during in vitro culture. Although various synchronization methods are available, they are not able to narrow the range of ages of parasites. A newly developed method is described that allows synchronization of parasites to produce cultures with an age range as low as 30 minutes. Methods Trophozoites and schizonts are enriched using Plasmion. The enriched late stage parasites are immobilized as a monolayer onto plastic Petri dishes using concanavalin A. Uninfected erythrocytes are placed onto the monolayer for a limited time period, during which time schizonts on the monolayer rupture and the released merozoites invade the fresh erythrocytes. The overlay is then taken off into a culture flask, resulting in a highly synchronized population of parasites. Results Plasmion treatment results in a 10- to 13-fold enrichment of late stage parasites. The monolayer method results in highly synchronized cultures of parasites where invasion has occurred within a very limited time window, which can be as low as 30 minutes. The method is simple, requiring no specialized equipment and relatively cheap reagents. Conclusions The new method for parasite synchronization results in highly synchronized populations of parasites, which will be useful for studies of the parasite asexual cell cycle.

  1. 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.

  2. Correlation between 'H' blood group antigen and Plasmodium falciparum invasion.

    Science.gov (United States)

    Pathak, Vrushali; Colah, Roshan; Ghosh, Kanjaksha

    2016-06-01

    The ABO blood group system is the most important blood group system in clinical practice. The relationship between Plasmodium falciparum and ABO blood groups has been studied for many years. This study was undertaken to investigate the abilities of different blood group erythrocytes to support in vitro growth of P. falciparum parasites. P. falciparum parasites of four different strains (3D7, 7G8, Dd2 and RKL9) were co-cultured with erythrocytes of blood group 'A', 'B', 'O' (n = 10 for each) and 'O(h)' (Bombay group) (n = 7) for 5 days. Statistically significant differences were observed on the fourth day among the mean percent parasitemias of 'O', non-'O' ('A' and 'B') and 'O(h)' group cultures. The parasitemias of four strains ranged from 12.23 to 14.66, 11.68 to 13.24, 16.89 to 22.3, and 7.37 to 11.27 % in 'A', 'B', 'O' and Bombay group cultures, respectively. As the expression of H antigen decreased from 'O' blood group to 'A' and 'B' and then to Bombay blood group, parasite invasion (percent parasitemia) also decreased significantly (p group erythrocytes were virtually converted to Bombay group-like erythrocytes by the treatment of anti-H lectins extracted from Ulex europaeus seeds. Mean percent parasitemia of lectin-treated cultures on the fourth day was significantly lower (p Bombay group erythrocyte cultures, thus further strengthening the hypothesis.

  3. Parasite virulence and disease severity in Plasmodium falciparum malaria.

    OpenAIRE

    Ribacke, Ulf

    2009-01-01

    Malaria stands out as one of the most important infectious diseases and one of the world s leading causes of death. Plasmodium falciparum is the parasite responsible for the great majority of severe disease syndromes and mortality, and affects mainly children and pregnant women. Despite intensive research efforts, the understanding of P. falciparum virulence is limited. Infections with the parasite cause everything from asymptomatic parasitemia to severe disease and death, a...

  4. Insulin reduces the requirement for serum in Plasmodium falciparum culture

    Directory of Open Access Journals (Sweden)

    Carlos Eduardo Tosta

    1984-03-01

    Full Text Available Insulin added to Plasmodium falciparum cultures (0.2 IU/ml reduced the requirement for human serum from ten to five percent. This represents an obvious advantage by its serum-sparing effect and by reducing the chances of using contaminated serum in cultures. The growth-promoting ability of insulin was observed eitherin culture- adapted P. falciparum or in newly-isolated samples.

  5. [Erythrocytes infected by Plasmodium falciparum activate human platelets].

    Science.gov (United States)

    Polack, B; Peyron, F; Sheick Zadiuddin, I; Kolodié, L; Ambroise-Thomas, P

    1990-01-01

    Blood platelets are involved in Plasmodium falciparum malaria pathology as shown by thrombocytopenia and increased plasma level of two alpha granule proteins: beta thromboglobulin (beta TG) and platelet factor 4 (PF4). In this study we demonstrate that Plasmodium falciparum parasitized erythrocytes activate directly the secretion of beta TG and PF4 by human platelets. This secretion is related to parasitemia and occurs immediately after contact. Treatment of parasited erythrocytes by trypsin and diffusion chamber experiments suggest that platelet activation is triggered by parasitic substances shed on erythrocyte membrane and released in the culture medium.

  6. Analysis of expressed sequence tags from Plasmodium falciparum.

    Science.gov (United States)

    Chakrabarti, D; Reddy, G R; Dame, J B; Almira, E C; Laipis, P J; Ferl, R J; Yang, T P; Rowe, T C; Schuster, S M

    1994-07-01

    An initiative was undertaken to sequence all genes of the human malaria parasite Plasmodium falciparum in an effort to gain a better understanding at the molecular level of the parasite that inflicts much suffering in the developing world. 550 random complimentary DNA clones were partially sequenced from the intraerythrocytic form of the parasite as one of the approaches to analyze the transcribed sequences of its genome. The sequences, after editing, generated 389 expressed sequence tag sites and over 105 kb of DNA sequences. About 32% of these clones showed significant homology with other genes in the database. These clones represent 340 new Plasmodium falciparum expressed sequence tags.

  7. Yurt Dışı Kökenli Plasmodium falciparum Suşlarının Tanısında Serolojik ve Moleküler Yöntemlerin Kullanılması

    OpenAIRE

    Eroglu, Fadime; GENÇ, Ahmet; Çürük, Mehmet Akif; Koltaş, İsmail Soner

    2017-01-01

    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...

  8. 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.

  9. Artemisinin-Resistant Plasmodium falciparum Malaria.

    Science.gov (United States)

    Fairhurst, Rick M; Dondorp, Arjen M

    2016-06-01

    For more than five decades, Southeast Asia (SEA) has been fertile ground for the emergence of drug-resistant Plasmodium falciparum malaria. After generating parasites resistant to chloroquine, sulfadoxine, pyrimethamine, quinine, and mefloquine, this region has now spawned parasites resistant to artemisinins, the world's most potent antimalarial drugs. In areas where artemisinin resistance is prevalent, artemisinin combination therapies (ACTs)-the first-line treatments for malaria-are failing fast. This worrisome development threatens to make malaria practically untreatable in SEA, and threatens to compromise global endeavors to eliminate this disease. A recent series of clinical, in vitro, genomics, and transcriptomics studies in SEA have defined in vivo and in vitro phenotypes of artemisinin resistance, identified its causal genetic determinant, explored its molecular mechanism, and assessed its clinical impact. Specifically, these studies have established that artemisinin resistance manifests as slow parasite clearance in patients and increased survival of early-ring-stage parasites in vitro; is caused by single nucleotide polymorphisms in the parasite's K13 gene, is associated with an upregulated "unfolded protein response" pathway that may antagonize the pro-oxidant activity of artemisinins, and selects for partner drug resistance that rapidly leads to ACT failures. In SEA, clinical studies are urgently needed to monitor ACT efficacy where K13 mutations are prevalent, test whether new combinations of currently available drugs cure ACT failures, and advance new antimalarial compounds through preclinical pipelines and into clinical trials. Intensifying these efforts should help to forestall the spread of artemisinin and partner drug resistance from SEA to sub-Saharan Africa, where the world's malaria transmission, morbidity, and mortality rates are highest.

  10. Unique properties of Plasmodium falciparum porphobilinogen deaminase.

    Science.gov (United States)

    Nagaraj, Viswanathan Arun; Arumugam, Rajavel; Gopalakrishnan, Bulusu; Jyothsna, Yeleswarapu Sri; Rangarajan, Pundi N; Padmanaban, Govindarajan

    2008-01-04

    The hybrid pathway for heme biosynthesis in the malarial parasite proposes the involvement of parasite genome-coded enzymes of the pathway localized in different compartments such as apicoplast, mitochondria, and cytosol. However, knowledge on the functionality and localization of many of these enzymes is not available. In this study, we demonstrate that porphobilinogen deaminase encoded by the Plasmodium falciparum genome (PfPBGD) has several unique biochemical properties. Studies carried out with PfPBGD partially purified from parasite membrane fraction, as well as recombinant PfPBGD lacking N-terminal 64 amino acids expressed and purified from Escherichia coli cells (DeltaPfPBGD), indicate that both the proteins are catalytically active. Surprisingly, PfPBGD catalyzes the conversion of porphobilinogen to uroporphyrinogen III (UROGEN III), indicating that it also possesses uroporphyrinogen III synthase (UROS) activity, catalyzing the next step. This obviates the necessity to have a separate gene for UROS that has not been so far annotated in the parasite genome. Interestingly, DeltaPfP-BGD gives rise to UROGEN III even after heat treatment, although UROS from other sources is known to be heat-sensitive. Based on the analysis of active site residues, a DeltaPfPBGDL116K mutant enzyme was created and the specific activity of this recombinant mutant enzyme is 5-fold higher than DeltaPfPBGD. More interestingly, DeltaPfPBGDL116K catalyzes the formation of uroporphyrinogen I (UROGEN I) in addition to UROGEN III, indicating that with increased PBGD activity the UROS activity of PBGD may perhaps become rate-limiting, thus leading to non-enzymatic cyclization of preuroporphyrinogen to UROGEN I. PfPBGD is localized to the apicoplast and is catalytically very inefficient compared with the host red cell enzyme.

  11. Pseudomonas aeruginosa septicaemia in a patient with severe Plasmodium falciparum

    DEFF Research Database (Denmark)

    Kharazmi, A; Høiby, N; Theander, T G

    1987-01-01

    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......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...

  12. [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.

  13. Biguanide-Atovaquone Synergy against Plasmodium falciparum In Vitro

    OpenAIRE

    2002-01-01

    The synergistic potential of a range of biguanides, their triazine metabolites, tetracyclines, and pyrimethamine in combination with atovaquone has been assessed. All five biguanides tested interacted synergistically with atovaquone against Plasmodium falciparum in vitro. All of the other compounds tested were either additive or antagonistic.

  14. 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...

  15. 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

  16. 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...

  17. Artemether-lumefantrine treatment of uncomplicated Plasmodium falciparum malaria

    DEFF Research Database (Denmark)

    Kofoed, Poul-Erik

    2015-01-01

    -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...

  18. Plasmodium falciparum infection causes proinflammatory priming of human TLR responses.

    NARCIS (Netherlands)

    McCall, M.B.B.; Netea, M.G.; Hermsen, C.C.; Jansen, T.; Jacobs, L.; Golenbock, D.; Ven, A.J.A.M. van der; Sauerwein, R.W.

    2007-01-01

    TLRs are a major group of pattern recognition receptors that are crucial in initiating innate immune responses and are capable of recognizing Plasmodium ligands. We have investigated TLR responses during acute experimental P. falciparum (P.f.) infection in 15 malaria-naive volunteers. TLR-4 response

  19. 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

  20. 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

  1. The prognostic value of schizontaemia in imported Plasmodium falciparum malaria

    NARCIS (Netherlands)

    M.E. van Wolfswinkel (Marlies); M. De Mendonça Melo (Mariana); K. Vliegenthart-Jongbloed (Klaske); R. Koelewijn (Rob); J.J. van Hellemond (Jaap); P.J.J. van Genderen (Perry)

    2012-01-01

    textabstractBackground: In Plasmodium falciparum infection, peripheral parasite counts do not always correlate well with the sequestered parasite burden. As erythrocytes parasitized with mature trophozoites and schizonts have a high tendency to adhere to the microvascular endothelium, they are often

  2. The prognostic value of schizontaemia in imported Plasmodium falciparum malaria

    NARCIS (Netherlands)

    M.E. van Wolfswinkel (Marlies); M. De Mendonça Melo (Mariana); K. Vliegenthart-Jongbloed (Klaske); R. Koelewijn (Rob); J.J. van Hellemond (Jaap); P.J.J. van Genderen (Perry)

    2012-01-01

    textabstractBackground: In Plasmodium falciparum infection, peripheral parasite counts do not always correlate well with the sequestered parasite burden. As erythrocytes parasitized with mature trophozoites and schizonts have a high tendency to adhere to the microvascular endothelium, they are often

  3. The epidemiology of Plasmodium falciparum gametocytes: weapons of mass dispersion.

    NARCIS (Netherlands)

    Drakeley, C.; Sutherland, C.; Bousema, J.T.; Sauerwein, R.W.; Targett, G.A.T.

    2006-01-01

    Much of the epidemiology of Plasmodium falciparum in Sub-Saharan Africa focuses on the prevalence patterns of asexual parasites in people of different ages, whereas the gametocytes that propagate the disease are often neglected. One expected benefit of the widespread introduction of artemisinin-base

  4. 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

  5. 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

  6. Genetic loci associated with delayed clearance of Plasmodium falciparum following artemisinin treatment in Southeast Asia

    Science.gov (United States)

    2013-01-02

    Genetic loci associated with delayed clearance of Plasmodium falciparum following artemisinin treatment in Southeast Asia Shannon Takala-Harrisona...resistant Plasmodium falcipa- rum malaria in western Cambodia could threaten prospects for malaria elimination. Identification of the genetic basis of...molecular markers Artemisinin-based combination therapies (ACTs) are the lead-ing treatment for Plasmodium falciparum malaria (1), and their use with

  7. Analyzing Plasmodium falciparum erythrocyte membrane protein 1 gene expression by a next generation sequencing based method

    DEFF Research Database (Denmark)

    Jespersen, Jakob S.; Petersen, Bent; Seguin-Orlando, Andaine;

    2013-01-01

    Plasmodium falciparum is responsible for most cases of severe malaria and causes >1 million deaths every year. The particular virulence of this Plasmodium species is highly associated with the expression of certain members of the Plasmodium falciparum erythrocyte membrane protein 1(PfEMP1) family...

  8. A molecular mechanism of artemisinin resistance in Plasmodium falciparum malaria.

    Science.gov (United States)

    Mbengue, Alassane; Bhattacharjee, Souvik; Pandharkar, Trupti; Liu, Haining; Estiu, Guillermina; Stahelin, Robert V; Rizk, Shahir S; Njimoh, Dieudonne L; Ryan, Yana; Chotivanich, Kesinee; Nguon, Chea; Ghorbal, Mehdi; Lopez-Rubio, Jose-Juan; Pfrender, Michael; Emrich, Scott; Mohandas, Narla; Dondorp, Arjen M; Wiest, Olaf; Haldar, Kasturi

    2015-04-30

    Artemisinins are the cornerstone of anti-malarial drugs. Emergence and spread of resistance to them raises risk of wiping out recent gains achieved in reducing worldwide malaria burden and threatens future malaria control and elimination on a global level. Genome-wide association studies (GWAS) have revealed parasite genetic loci associated with artemisinin resistance. However, there is no consensus on biochemical targets of artemisinin. Whether and how these targets interact with genes identified by GWAS, remains unknown. Here we provide biochemical and cellular evidence that artemisinins are potent inhibitors of Plasmodium falciparum phosphatidylinositol-3-kinase (PfPI3K), revealing an unexpected mechanism of action. In resistant clinical strains, increased PfPI3K was associated with the C580Y mutation in P. falciparum Kelch13 (PfKelch13), a primary marker of artemisinin resistance. Polyubiquitination of PfPI3K and its binding to PfKelch13 were reduced by the PfKelch13 mutation, which limited proteolysis of PfPI3K and thus increased levels of the kinase, as well as its lipid product phosphatidylinositol-3-phosphate (PI3P). We find PI3P levels to be predictive of artemisinin resistance in both clinical and engineered laboratory parasites as well as across non-isogenic strains. Elevated PI3P induced artemisinin resistance in absence of PfKelch13 mutations, but remained responsive to regulation by PfKelch13. Evidence is presented for PI3P-dependent signalling in which transgenic expression of an additional kinase confers resistance. Together these data present PI3P as the key mediator of artemisinin resistance and the sole PfPI3K as an important target for malaria elimination.

  9. 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...

  10. A Next-generation Genetically Attenuated Plasmodium falciparum Parasite Created by Triple Gene Deletion

    OpenAIRE

    Mikolajczak, Sebastian A.; Lakshmanan, Viswanathan; Fishbaugher, Matthew; Camargo, Nelly; Harupa, Anke; Kaushansky, Alexis; Douglass, Alyse N.; Baldwin, Michael; Healer, Julie; O'Neill, Matthew; Phuong, Thuan; Cowman, Alan; Kappe, Stefan H. I.

    2014-01-01

    Immunization with live-attenuated Plasmodium sporozoites completely protects against malaria infection. Genetic engineering offers a versatile platform to create live-attenuated sporozoite vaccine candidates. We previously generated a genetically attenuated parasite (GAP) by deleting the P52 and P36 genes in the NF54 wild-type (WT) strain of Plasmodium falciparum (Pf p52−/p36− GAP). Preclinical assessment of p52−/p36− GAP in a humanized mouse model indicated an early and severe liver stage gr...

  11. 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.

  12. 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

  13. Susceptibility of Colombian Plasmodium falciparum isolates to 4-aminoquinolines and the definition of amodiaquine resistance in vitro

    Directory of Open Access Journals (Sweden)

    Diego F Echeverry

    2006-05-01

    Full Text Available There are wide variations in the threshold used to define in vitro resistance of Plasmodium falciparum to amodiaquine (AQ, probably due to differences in methodology and interpretation. In vitro susceptibility data of Colombian P. falciparum strains to AQ and N-desethylamodiaquine is used to illustrate the need to standardized methodologies and compare inhibitory concentrations, instead of resistant/susceptible phenotypes, when studying the mechanisms of resistance to AQ and monitoring drug susceptibility trends in the field.

  14. 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.

  15. Plasmodium Falciparum Versus Plasmodium Vivax: Which Is a Lesser Evil?

    Directory of Open Access Journals (Sweden)

    Rathod Chirag C, Deshpande Shubhangi V, Rana Himanshu M, Godbole Varsha Y, Patel Amul, Patel Vaibhav, Darad Dimple, Panchal Maulik

    2012-09-01

    Full Text Available Background: With changing spectrum, different grades of biochemical & haematological changes generally found to be more severe with p. falciparum, now frequently seen with p. vivax. Present study intends to find species specific differences in diseases progression & complications. Methodology: A retrospective study of Malaria-patients admitted at GMERS Medical College & Hospital, Vadodara from january-2011to december-2011 was done. p. falciparum, P. Vivax were diagnosed by demonstrating asexual forms of parasites in peripheral blood smear, haematological & biochemical tests were analyzed. Results: Out of 1093 cases, 781 were slide positive, remaining 312 were treated on clinical-ground .Of 781 cases, 443 (56% p. falciparum, 327 (42% P. Vivax and 11(2% were mixed Infection. Male to female ratio was 1.8:1&0.8:1 in p. falciparum & P. vivax, respectively. Fever, Prodroms, GI symptoms, Liver -dysfunction (51%vs47%, Renal- dysfunction (52%vs48% were equally frequent; whereas Hemolysis, Bleeding tendency, Breathlessness and altered sensorium were more in p. falciparum. Anemia (56%, Thrombocytopenia (60%, Pancytopenia (54%, Hemolysis (65% was more frequent in p. falciparum. Leucopenia (54% was more frequent in p. Vivax. Conclusion: In contrast to earlier studies, which have proven p. falciparum to be more fatal & complicated, it was noted in present study that P. Vivax species was frequent cause of overall slide-positive cases causing complications head to head with p. falciparum. Anemia, Hepato-renal dysfunctions were equally frequent, nonfatal leucopenia more in p. Vivax, while hemolysis and thrombocytopenia was more in p. falciparum. If ignored complications can alter clinical course & be equally fatal in p. vivax malaria. Hence p. vivax can no more be considered as benign infection and can be equally lethal.

  16. 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...

  17. 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...

  18. 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...

  19. Naturally acquired immunity to Plasmodium falciparum malaria in Africa

    DEFF Research Database (Denmark)

    Hviid, Lars

    2005-01-01

    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......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...

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

    National Research Council Canada - National Science Library

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

    2005-01-01

    The human malarial parasite Plasmodium falciparum exports proteins to destinations within its host erythrocyte, including cytosol, surface and membranous profiles of parasite origin termed Maurer's clefts...

  1. Polycyclic amines as chloroquine resistance modulating agents in Plasmodium falciparum.

    Science.gov (United States)

    Joubert, Jacques; Kapp, Erika; Taylor, Dale; Smith, Peter J; Malan, Sarel F

    2016-02-15

    Pentacycloundecylamines (PCUs) and adamantane amines, such as NGP1-01 (1) and amantadine, have shown significant channel blocking activities. They are postulated to act as chemosensitizers and circumvent the resistance of the plasmodia parasite against chloroquine (CQ) by inhibiting the p-glycoprotein efflux pump and enabling the accumulation of CQ inside the parasite digestive vacuole. Twelve polycyclic amines containing either a PCU or adamantane amine moiety conjugated to different aromatic functionalities through various tethered linkers were selected based on their channel blocking abilities and evaluated as potential chemosensitizers. Compounds 2, 4, 5 and 10 showed significant voltage-gated calcium channel (VGCC) blocking ability (IC50=0.27-35 μM) and were able to alter the CQ IC50 in differing degrees (45-81%) in the multidrug resistant Plasmodium falciparum Dd2 isolate. Among them, the PCU-dansyl amine compound (4) displayed the best potential to act as a chemosensitizer against the Dd2 strain at a 1 μM concentration (RMI=0.19) while displaying moderate antiplasmodial activity (Dd2 IC50=6.25 μM) and low in vitro cytotoxicity against a mammalian cell line (CHO, IC50=119 μM). Compounds 2 and 10 also showed some promising chemosensitizing abilities (RMI=0.36 and 0.35 respectively). A direct correlation was found between the VGCC blocking ability of these polycyclic amines and their capacity to act as CQ resistance modulating agents.

  2. [Plasmodium falciparum malaria: epidemiology and clinical features at Tarapoto Hospital].

    Science.gov (United States)

    Calderon, J; Rodriguez, J; Romero, D

    1997-01-01

    A retrospective study was conducted of the clinical records of 41 patients discharged from a hospital in Tarapoto, Peru, between August 1992 and June 1996 following treatment for Plasmodium falciparum malaria. Patients ranged in age from 18 to 65 years; 25 were male. The cases were uniformly distributed throughout the year. The duration of illness averaged 11 days. At admission, 40 patients had fever, 36 had shaking chills, 29 had headache, 21 had nausea and vomiting, 21 had hyporexia, 15 had pallor, and 13 had splenomegaly. 3 of the 16 women were pregnant. 7 patients reported a history of malaria. The admission diagnosis was malaria in 33 cases. 31 patients were treated with chloroquine; 18 were subsequently treated with pyrimethamine-sulfadoxin and 1 received doxycycline. No cases of grave illness or death occurred. The increasing presence of Plasmodium falciparum malaria in the Peruvian lowlands should promote review of the adequacy of control programs.

  3. 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—preferentiall......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....

  4. Peptide Inhibition of Topoisomerase IB from Plasmodium falciparum

    Directory of Open Access Journals (Sweden)

    Amit Roy

    2011-01-01

    Full Text Available Control of diseases inflicted by protozoan parasites such as Leishmania, Trypanosoma, and Plasmodium, which pose a serious threat to human health worldwide, depends on a rather small number of antiparasite drugs, of which many are toxic and/or inefficient. Moreover, the increasing occurrence of drug-resistant parasites emphasizes the need for new and effective antiprotozoan drugs. In the current study, we describe a synthetic peptide, WRWYCRCK, with inhibitory effect on the essential enzyme topoisomerase I from the malaria-causing parasite Plasmodium falciparum. The peptide inhibits specifically the transition from noncovalent to covalent DNA binding of P. falciparum topoisomerase I, while it does not affect the ligation step of catalysis. A mechanistic explanation for this inhibition is provided by molecular docking analyses. Taken together the presented results suggest that synthetic peptides may represent a new class of potential antiprotozoan drugs.

  5. 3-Halo Chloroquine Derivatives Overcome Plasmodium falciparum Chloroquine Resistance Transporter-Mediated Drug Resistance in P. falciparum.

    Science.gov (United States)

    Edaye, Sonia; Tazoo, Dagobert; Bohle, D Scott; Georges, Elias

    2015-12-01

    Polymorphism in the Plasmodium falciparum chloroquine resistance transporter (PfCRT) was shown to cause chloroquine resistance. In this report, we examined the antimalarial potential of novel 3-halo chloroquine derivatives (3-chloro, 3-bromo, and 3-iodo) against chloroquine-susceptible and -resistant P. falciparum. All three derivatives inhibited the proliferation of P. falciparum; with 3-iodo chloroquine being most effective. Moreover, 3-iodo chloroquine was highly effective at potentiating and reversing chloroquine toxicity of drug-susceptible and -resistant P. falciparum.

  6. Synthesis, Biological Evaluation and Structure-Activity Relationships of New Quinoxaline Derivatives as Anti-Plasmodium falciparum Agents

    Directory of Open Access Journals (Sweden)

    Ana Gil

    2014-02-01

    Full Text Available We report the synthesis and antimalarial activities of eighteen quinoxaline and quinoxaline 1,4-di-N-oxide derivatives, eight of which are completely novel. Compounds 1a and 2a were the most active against Plasmodium falciparum strains. Structure-activity relationships demonstrated the importance of an enone moiety linked to the quinoxaline ring.

  7. Synthesis, biological evaluation and structure-activity relationships of new quinoxaline derivatives as anti-Plasmodium falciparum agents.

    Science.gov (United States)

    Gil, Ana; Pabón, Adriana; Galiano, Silvia; Burguete, Asunción; Pérez-Silanes, Silvia; Deharo, Eric; Monge, Antonio; Aldana, Ignacio

    2014-02-18

    We report the synthesis and antimalarial activities of eighteen quinoxaline and quinoxaline 1,4-di-N-oxide derivatives, eight of which are completely novel. Compounds 1a and 2a were the most active against Plasmodium falciparum strains. Structure-activity relationships demonstrated the importance of an enone moiety linked to the quinoxaline ring.

  8. Synthesis, Biological Evaluation and Structure-Activity Relationships of New Quinoxaline Derivatives as Anti-Plasmodium falciparum Agents

    OpenAIRE

    Ana Gil; Adriana Pabón; Silvia Galiano; Asunción Burguete; Silvia Pérez-Silanes; Eric Deharo; Antonio Monge; Ignacio Aldana

    2014-01-01

    We report the synthesis and antimalarial activities of eighteen quinoxaline and quinoxaline 1,4-di-N-oxide derivatives, eight of which are completely novel. Compounds 1a and 2a were the most active against Plasmodium falciparum strains. Structure-activity relationships demonstrated the importance of an enone moiety linked to the quinoxaline ring.

  9. Surface antigens and virulence in Plasmodium falciparum malaria

    OpenAIRE

    Normark, Johan

    2008-01-01

    Plasmodium falciparum is an intracellular protozoan that may cause severe forms of malaria. It is a major world health hazard and reaps the highest toll among the children and pregnant mothers of the developing world. An Anopheles mosquito vector injects the pathogen when taking a blood meal. After multiplication in cells of the liver, the parasite escapes and infects red blood cells in a cyclic manner and this is when the clinical manifestations of malaria as a disease beco...

  10. 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 on t...... 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....

  11. Genes for Glycosylphosphatidylinositol Toxin Biosynthesis in Plasmodium falciparum

    OpenAIRE

    Delorenzi, Mauro; Sexton, Adrienne; Shams-Eldin, Hosam; Schwarz, Ralph T.; Speed, Terry; Schofield, Louis

    2002-01-01

    About 2.5 million people die of Plasmodium falciparum malaria every year. Fatalities are associated with systemic and organ-specific inflammation initiated by a parasite toxin. Recent studies show that glycosylphosphatidylinositol (GPI) functions as the dominant parasite toxin in the context of infection. GPIs also serve as membrane anchors for several of the most important surface antigens of parasite invasive stages. GPI anchoring is a complex posttranslational modification produced through...

  12. Structure of Plasmodium falciparum ADP-ribosylation factor 1

    Energy Technology Data Exchange (ETDEWEB)

    Cook, William J.; Smith, Craig D.; Senkovich, Olga; Holder, Anthony A.; Chattopadhyay, Debasish (UAB); (NIMR)

    2011-09-26

    Vesicular trafficking may play a crucial role in the pathogenesis and survival of the malaria parasite. ADP-ribosylation factors (ARFs) are among the major components of vesicular trafficking pathways in eukaryotes. The crystal structure of ARF1 GTPase from Plasmodium falciparum has been determined in the GDP-bound conformation at 2.5 {angstrom} resolution and is compared with the structures of mammalian ARF1s.

  13. CRISPR-mediated genome editing of Plasmodium falciparum malaria parasites.

    Science.gov (United States)

    Lee, Marcus Cs; Fidock, David A

    2014-01-01

    The development of the CRISPR-Cas system is revolutionizing genome editing in a variety of organisms. The system has now been used to manipulate the genome of Plasmodium falciparum, the most lethal malaria-causing species. The ability to generate gene deletions or nucleotide substitutions rapidly and economically promises to accelerate the analysis of novel drug targets and to help elucidate the function of specific genes or gene families, while complementing genome-wide association studies.

  14. CRISPR-mediated genome editing of Plasmodium falciparum malaria parasites

    OpenAIRE

    Lee, Marcus CS; David A Fidock

    2014-01-01

    The development of the CRISPR-Cas system is revolutionizing genome editing in a variety of organisms. The system has now been used to manipulate the genome of Plasmodium falciparum, the most lethal malaria-causing species. The ability to generate gene deletions or nucleotide substitutions rapidly and economically promises to accelerate the analysis of novel drug targets and to help elucidate the function of specific genes or gene families, while complementing genome-wide association studies.

  15. Artesunate plus pyronaridine for treating uncomplicated Plasmodium falciparum malaria

    OpenAIRE

    Bukirwa, Hasifa; Unnikrishnan, B; Kramer, Christine V; Sinclair, David; Nair, Suma; Tharyan, Prathap

    2014-01-01

    Background The World Health Organization (WHO) recommends that people with uncomplicated Plasmodium falciparum malaria are treated using Artemisinin-based Combination Therapy (ACT). ACT combines three-days of a short-acting artemisinin derivative with a longer-acting antimalarial which has a different mode of action. Pyronaridine has been reported as an effective antimalarial over two decades of use in parts of Asia, and is currently being evaluated as a partner drug for artesunate. Objective...

  16. Aislamiento y mantenimiento in vitro de Plasmodium falciparum

    Directory of Open Access Journals (Sweden)

    Blanca Pardave L

    1997-07-01

    Full Text Available Se aislaron 08 cepas de Plasmodium falciparum a partir de 10 pacientes. Luego fueron adaptadas y mantenidas en cultivo in vitro durante 60 días en eritrocitos humanos grupo O, en medio RPMI 1640 enriquecido con plasma humano grupo O, bajo una atmósfera de 5% de CO2, 5% de O2 y 90% de Nitrógeno y luego preservados a -70ºC.

  17. 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...... 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...

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

    Science.gov (United States)

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

    2008-11-01

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

  19. Monitoring PfMDR1 transport in Plasmodium falciparum.

    Science.gov (United States)

    Reiling, Sarah J; Rohrbach, Petra

    2015-07-15

    The Plasmodium falciparum multidrug resistance 1 transporter, PfMDR1, contains five amino acid polymorphisms that are suggested to be involved in altered drug transport from the parasite's cytosol into the digestive vacuole (DV). Transport of a substrate into another intracellular compartment influences drug availability at its site of action, therefore making the parasite more susceptible or resistant to a drug. Fluo-4 is a known fluorescent substrate that can be used as a molecular tool to investigate transport dynamics of PfMDR1 in many parasite strains. Six P. falciparum strains with varying PfMDR1 mutations were loaded with Fluo-4 AM. Accumulation of the fluorophore in the DV was measured using confocal microscopy. The role of a key amino acid mutation was verified using selected parasite clones with point mutations at PfMDR1 amino acid position 1042. Equal expression of PfMDR1 was confirmed by Western blot. Fluo-4 was transported by PfMDR1 into the DV of most drug-sensitive and -resistant parasites. Asparagine at PfMDR1 amino acid position 1042 was crucial for Fluo-4 transport, while the N1042D substitution abolished Fluo-4 transport. Competition studies of Fluo-4 with chloroquine, quinine and mefloquine were performed on parasites harbouring asparagine at position 1042. A distinct Fluo-4 transport inhibition pattern for each tested anti-malarial drug was observed in parasite strains of different genetic background. This study demonstrates that Fluo-4 can be used to investigate PfMDR1 transport dynamics in both drug-sensitive and -resistant parasites. Furthermore, direct evidence of altered Fluo-4 transport in PfMDR1 is linked to a single amino acid mutation in the substrate binding pocket. This system offers a great tool to investigate the role of substrate transport by PfMDR1 and the mutations necessary to support transport, which would lead to new insights for the development of novel anti-malarial drugs.

  20. 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

  1. 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

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

    Directory of Open Access Journals (Sweden)

    Steve M Taylor

    Full Text Available 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

  3. 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.

  4. Distribution of two species of malaria, Plasmodium falciparum and Plasmodium vivax, on Lombok Island, Indonesia.

    Science.gov (United States)

    Nagao, Yoshiro; Dachlan, Yoes Prijatna; Soedarto; Hidajati, Sri; Yotopranoto, Subagyo; Kusmartisnawati; Subekti, Sri; Ideham, Bariah; Tsuda, Yoshio; Kawabata, Masato; Takagi, Masahiro; Looareesuwan, Somchai

    2003-09-01

    Medical and entomological surveys were conducted to determine the risk factors of Plasmodium falciparum and P. vivax infections on Lombok Island, Indonesia, to find the risk factors and the main mosquito vectors for each malaria. Multivariate longitudinal analysis demonstrated two significant risk factors for infection with P. falciparum: disappearance of P. vivax parasitemia (p<0.001) and a specific study site (p<0.001). In contrast, younger age (p=0.024) and the interpolated virtual density of An. subpictus (p=0.041) were significantly associated with increased risk of infection with P. vivax. Thus, it seems that the distribution of P. vivax was determined largely by the presence of An. subpictus, whilst that of P. falciparum was influenced by antagonism with P. vivax. This result shows the importance of following-up treated P. vivax patients to identify recrudescence of P. falciparum in this area.

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

    Science.gov (United States)

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

    2016-01-01

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

  6. The heat shock protein 90 of Plasmodium falciparum and antimalarial activity of its inhibitor, geldanamycin

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    Barik Sailen

    2003-09-01

    Full Text Available Abstract Background The naturally occurring benzoquinone ansamycin compound, geldanamycin (GA, is a specific inhibitor of heat shock protein 90 (Hsp90 and is a potential anticancer agent. Since Plasmodium falciparum has been reported to have an Hsp90 ortholog, we tested the possibility that GA might inhibit it and thereby display antiparasitic activity. Results We provide direct recombinant DNA evidence for the Hsp90 protein of Plasmodium falciparum, the causative agent of fatal malaria. While the mRNA of Hsp90 was mainly expressed in ring and trophozoite stages, the protein was found in all stages, although schizonts contained relatively lower amounts. In vitro the parasitic Hsp90 exhibited an ATP-binding activity that could be specifically inhibited by GA. Plasmodium growth in human erythrocyte culture was strongly inhibited by GA with an IC50 of 20 nM, compared to the IC50 of 15 nM for chloroquine (CQ under identical conditions. When used in combination, the two drugs acted synergistically. GA was equally effective against CQ-sensitive and CQ-resistant strains (3D7 and W2, respectively and on all erythrocytic stages of the parasite. Conclusions Together, these results suggest that an active and essential Hsp90 chaperone cycle exists in Plasmodium and that the ansamycin antibiotics will be an important tool to dissect its role in the parasite. Additionally, the favorable pharmacology of GA, reported in human trials, makes it a promising antimalarial drug.

  7. Plasmodium falciparum drug resistance in Angola

    OpenAIRE

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

    2016-01-01

    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 ...

  8. Congenital Plasmodium falciparum infection in neonates in Muheza District, Tanzania

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    Kimera Sharadhuli I

    2008-07-01

    Full Text Available Abstract Background Although recent reports on congenital malaria suggest that the incidence is increasing, it is difficult to determine whether the clinical disease is due to parasites acquired before delivery or as a result of contamination by maternal blood at birth. Understanding of the method of parasite acquisition is important for estimating the time incidence of congenital malaria and design of preventive measures. The aim of this study was to determine whether the first Plasmodium falciparum malaria disease in infants is due to same parasites present on the placenta at birth. Methods Babies born to mothers with P. falciparum parasites on the placenta detected by PCR were followed up to two years and observed for malaria episodes. Paired placental and infant peripheral blood samples at first malaria episode within first three months of life were genotyped (msp2 to determine genetic relatedness. Selected amplifications from nested PCR were sequenced and compared between pairs. Results Eighteen (19.1% out of 95 infants who were followed up developed clinical malaria within the first three months of age. Eight pairs (60% out of 14 pairs of sequenced placental and cord samples were genetically related while six (40% were genetically unrelated. One pair (14.3% out of seven pairs of sequenced placental and infants samples were genetically related. In addition, infants born from primigravidae mothers were more likely to be infected with P. falciparum (P P. falciparum infection earlier than those from secundigravidae and primigravidae mothers (RR = 1.43. Conclusion Plasmodium falciparum malaria parasites present on the placenta as detected by PCR are more likely to result in clinical disease (congenital malaria in the infant during the first three months of life. However, sequencing data seem to question the validity of this likelihood. Therefore, the relationship between placental parasites and first clinical disease need to be confirmed in

  9. Role of Different Pfcrt and Pfmdr-1 Mutations in Conferring Resistance to Antimalaria Drugs in Plasmodium falciparum

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    Zaid O. Ibraheem

    2014-01-01

    Full Text Available Emergence of drugs resistant strains of Plasmodium falciparum has augmented the scourge of malaria in endemic areas. Antimalaria drugs act on different intracellular targets. The majority of them interfere with digestive vacuoles (DVs while others affect other organelles, namely, apicoplast and mitochondria. Prevention of drug accumulation or access into the target site is one of the mechanisms that plasmodium adopts to develop resistance. Plasmodia are endowed with series of transporters that shuffle drugs away from the target site, namely, pfmdr (Plasmodium falciparum multidrug resistance transporter and pfcrt (Plasmodium falciparum chloroquine resistance transporter which exist in DV membrane and are considered as putative markers of CQ resistance. They are homologues to human P-glycoproteins (P-gh or multidrug resistance system and members of drug metabolite transporter (DMT family, respectively. The former mediates drifting of xenobiotics towards the DV while the latter chucks them outside. Resistance to drugs whose target site of action is intravacuolar develops when the transporters expel them outside the DVs and vice versa for those whose target is extravacuolar. In this review, we are going to summarize the possible pfcrt and pfmdr mutation and their role in changing plasmodium sensitivity to different anti-Plasmodium drugs.

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

    Science.gov (United States)

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

    2016-01-01

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

  11. 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

  12. Growth and immunity conferred by a Plasmodium falciparum temperature sensitive mutant in Panamanian owl monkeys.

    Science.gov (United States)

    Inselburg, J; Rossan, R N; Escajadillo, A

    1989-05-01

    We have compared the growth of the wild type Plasmodium falciparum strain Honduras 1 and a previously isolated temperature sensitive mutant of it, AP1-16, in Panamanian owl monkeys. We examined serially infected splenectomized and normal animals that were initially infected with cultured parasites that had been grown in a mixture of owl monkey and human erythrocytes. Initial infections in splenectomized monkeys were marked by multiple recrudescences. The mutant grew less well than the wild type in the splenectomized monkeys, as determined by lower peak and total parasitemias. In the splenectomized monkeys tested by rechallenge with the wild type parasite, the mutant stimulated a comparable degree of protection. That protection was manifested in 2 ways. There was a marked reduction in the level of the primary parasitemia in the rechallenged monkeys and an absence of recrudescent parasitemias after the primary parasitemia. The potential value of generating and studying temperature sensitive P. falciparum strains that show attenuated growth is considered.

  13. 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...

  14. 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

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

    DEFF Research Database (Denmark)

    Oberli, Alexander; Zurbrügg, Laura; Rusch, Sebastian;

    2016-01-01

    Adherence of Plasmodium falciparum-infected erythrocytes to host endothelium is conferred through the parasite-derived virulence factor P. falciparum erythrocyte membrane protein 1 (PfEMP1), the major contributor to malaria severity. PfEMP1 located at knob structures on the erythrocyte surface is...

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

    Science.gov (United States)

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

    2014-01-20

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

  17. Artemisinin resistance in Plasmodium falciparum: A process linked to dormancy?

    Science.gov (United States)

    Cheng, Qin; Kyle, Dennis E; Gatton, Michelle L

    2012-12-01

    Artemisinin (ART) based combination therapy (ACT) is used as the first line treatment of uncomplicated falciparum malaria in over 100 countries and is the cornerstone of malaria control and elimination programs in these areas. However, despite the high potency and rapid parasite killing action of ART derivatives there is a high rate of recrudescence associated with ART monotherapy and recrudescence is not uncommon even when ACT is used. Compounding this problem are reports that some parasites in Cambodia, a known foci of drug resistance, have decreased in vivo sensitivity to ART. This raises serious concerns for the development of ART resistance in the field even though no major phenotypic and genotypic changes have yet been identified in these parasites. In this article we review available data on the characteristics of ART, its effects on Plasmodium falciparum parasites and present a hypothesis to explain the high rate of recrudescence associated with this potent class of drugs and the current enigma surrounding ART resistance.

  18. 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.

    2012-01-01

    Although sickle cell trait protects against severe disease due to Plasmodium falciparum, it has not been clear whether sickle trait also protects against asymptomatic infection (parasitemia). To address this question, the authors identified 171 persistently smear-negative children and 450 asymptomatic persistently smear-positive children in Bancoumana, Mali (June 1996 to June 1998). They then followed both groups for 2 years using a cohort-based strategy. Among the 171 children with persistently negative smears, the median time for conversion to smear-positive was longer for children with sickle trait than for children without (274 vs. 108 days, P sickle trait than for children without (190 vs. 365 days; P = 0.02). These protective effects of sickle trait against asymptomatic P. falciparum infection under conditions of natural transmission were demonstrable using a cohort-based approach but not when the same data were examined using a cross-sectional approach. PMID:23035141

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

    Science.gov (United States)

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

    2016-05-01

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

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

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    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.

  1. PENGEMBANGAN BIAKAN IN-VITRO PLASMODIUM FALCIPARUM SECARA KONTINU

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    Sekar Tuti

    2012-09-01

    Full Text Available To support malaria research on its' serology/immunology, chemotherapy, drug sensitivity aspects etc. especially for falciparum malaria, a large amount of antigen (parasites is needed. These antigen could not be obtained from patients in the field only. Considering this situation, attempts have been made to develop a Plasmodium falciparum continuous culture   in-vitro following a method introduced  by Trager and Jensen (1976. In our laboratory, the parasite grew and multiplied nicely for 60 days. During that period of cultivation, a large amount of parasites (mostly mature trophozoite and schizont stages have been collected for antigen production. Several tubes of mostly young trophozoites stage have been preserved, it can be cultured again in the future or transported to another laboratory for further culture.

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

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    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.

  3. A Plasmodium falciparum Homologue of Plasmodium vivax Reticulocyte Binding Protein (PvRBP1) Defines a Trypsin-resistant Erythrocyte Invasion Pathway

    Science.gov (United States)

    Rayner, Julian C.; Vargas-Serrato, Esmeralda; Huber, Curtis S.; Galinski, Mary R.; Barnwell, John W.

    2001-01-01

    Invasion of erythrocytes by Plasmodium merozoites is an intricate process involving multiple receptor-ligand interactions. The glycophorins and an unknown trypsin sensitive factor are all erythrocyte receptors used during invasion by the major human pathogen Plasmodium falciparum. However, only one erythrocyte receptor, Glycophorin A, has a well-established cognate parasite ligand, the merozoite protein erythrocyte binding antigen-175 (EBA-175). The involvement of several other parasite proteins during invasion have been proposed, but no direct evidence links them with a specific invasion pathway. Here we report the identification and characterization of P. falciparum normocyte binding protein 1 (PfNBP1), an ortholog of Plasmodium vivax reticulocyte binding protein-1. PfNBP1 binds to a sialic acid dependent trypsin-resistant receptor on the erythrocyte surface that appears to be distinct from known invasion receptors. Antibodies against PfNBP1 can inhibit invasion of trypsinized erythrocytes and two P. falciparum strains that express truncated PfNBP1 are unable to invade trypsinized erythrocytes. One of these strain, 7G8, also does not invade Glycophorin B–negative erythrocytes. PfNBP1 therefore defines a novel trypsin-resistant invasion pathway and adds a level of complexity to current models for P. falciparum erythrocyte invasion. PMID:11733572

  4. 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 ...... 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....

  5. Wanted Plasmodium falciparum, dead or alive

    Directory of Open Access Journals (Sweden)

    Fatimata Sow

    2015-07-01

    Full Text Available Mechanisms of cell death in unicellular parasites have been subjects of debate for the last decade, with studies demonstrating evidence of apoptosis or non-apoptosis like mechanisms, including necrosis, and autophagy. Recent clarifications on the definition of regulated or accidental cell death by The Nomenclature Committee on Cell Death provides an opportunity to reanalyze some data, re-evaluate conclusions in the light of parasite diversity, and to propose alternative arguments in the context of malaria drug resistance, considering lack of really new drugs in the pipeline. Deciphering the mechanisms of death may help in detection of new drug targets and the design of innovative drugs. However, classifications have been evolving rapidly since initial description of “programmed cell death”, leading to some uncertainty as to whether Plasmodium cell death is accidental or regulated.

  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.

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

    Science.gov (United States)

    Garver, Lindsey S; Dong, Yuemei; Dimopoulos, George

    2009-03-01

    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 development of P. falciparum

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

    Science.gov (United States)

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

    2016-03-16

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

  10. Synthesis of novel triazole-linked mefloquine derivatives: biological evaluation against Plasmodium falciparum.

    Science.gov (United States)

    Hamann, Anton R; de Kock, Carmen; Smith, Peter J; van Otterlo, Willem A L; Blackie, Margaret A L

    2014-12-01

    Using 2,8-bis(trifluoromethyl)quinoline, the pharmacophore of mefloquine, as scaffold, eleven novel triazole-linked compounds have been synthesised by the application of CuAAC chemistry. The in vitro biological activity of the compounds on the Plasmodium falciparum chloroquine-sensitive strain NF54 was then determined. The compounds all showed IC50s in the lower μM range with (1R,3S,5R)-N-{[1-(2,8-bis(trifluoromethyl)quinoline-4-yl)-1H-1,2,3-triazol-4-yl]methyl}adamantan-2-amine (29) exhibiting the best activity of 1.00 μM.

  11. Tudor domain proteins in protozoan parasites and characterization of Plasmodium falciparum tudor staphylococcal nuclease.

    Science.gov (United States)

    Hossain, Manzar J; Korde, Reshma; Singh, Shivani; Mohmmed, Asif; Dasaradhi, P V N; Chauhan, V S; Malhotra, Pawan

    2008-04-01

    RNA-binding proteins play key roles in post-transcriptional regulation of gene expression. In eukaryotic cells, a multitude of RNA-binding proteins with several RNA-binding domains/motifs have been described. Here, we show the existence of two Tudor domain containing proteins, a survival of motor neuron (SMN)-like protein and a Staphylococcus aureus nuclease homologue referred to as TSN, in Plasmodium and other protozoan parasites. Activity analysis shows that Plasmodium falciparum TSN (PfTSN) possesses nuclease activity and Tudor domain is the RNA-binding domain. A specific inhibitor of micrococcal nucleases, 3',5'-deoxythymidine bisphosphate (pdTp) inhibits the nuclease as well as RNA-binding activities of the protein. PfTSN shows a predominant nuclear localization. Treatment of P. falciparum with pdTp, inhibited in vitro growth of both chloroquine-sensitive and chloroquine-resistant strains of P. falciparum, while a four fold concentration of pdTp did not have any significant effect on the mammalian cell line, Huh-7D12. Altogether, these results suggest that PfTSN is an essential enzyme in the parasite's life cycle.

  12. Sero-epidemiological evaluation of Plasmodium falciparum malaria in Senegal.

    Science.gov (United States)

    Sylla, Khadime; Tine, Roger Clément Kouly; Ndiaye, Magatte; Sow, Doudou; Sarr, Aïssatou; Mbuyi, Marie Louise Tshibola; Diouf, Ibrahima; Lô, Amy Colé; Abiola, Annie; Seck, Mame Cheikh; Ndiaye, Mouhamadou; Badiane, Aïda Sadikh; N'Diaye, Jean Louis A; Ndiaye, Daouda; Faye, Oumar; Dieng, Thérèse; Dieng, Yémou; Ndir, Oumar; Gaye, Oumar; Faye, Babacar

    2015-07-16

    In Senegal, a significant decrease of malaria transmission intensity has been noted the last years. Parasitaemia has become lower and, therefore, more difficult to detect by microscopy. In the context of submicroscopic parasitaemia, it has become relevant to rely on relevant malaria surveillance tools to better document malaria epidemiology in such settings. Serological markers have been proposed as an essential tool for malaria surveillance. This study aimed to evaluate the sero-epidemiological situation of Plasmodium falciparum malaria in two sentinel sites in Senegal. Cross-sectional surveys were carried out in Velingara (south Senegal) and Keur Soce (central Senegal) between September and October 2010. Children under 10 years old, living in these areas, were enrolled using two-level, random sampling methods. P. falciparum infection was diagnosed using microscopy. P. falciparum antibodies against circumsporozoite protein (CSP), apical membrane protein (AMA1) and merozoite surface protein 1_42 (MSP1_42) were measured by ELISA method. A stepwise logistic regression analysis was done to assess factors associated with P. falciparum antibodies carriage. A total of 1,865 children under 10 years old were enrolled. The overall falciparum malaria prevalence was 4.99% with high prevalence in Velingara of 10.03% compared to Keur Soce of 0.3%. Symptomatic malaria cases (fever associated with parasitaemia) represented 17.37%. Seroprevalence of anti-AMA1, anti-MSP1_42 and anti-CSP antibody was 38.12, 41.55 and 40.38%, respectively. The seroprevalence was more important in Velingara and increased with age, active malaria infection and area of residence. The use of serological markers can contribute to improved malaria surveillance in areas with declining malaria transmission. This study provided useful baseline information about the sero-epidemiological situation of malaria in Senegal and can contribute to the identification of malaria hot spots in order to concentrate

  13. Brain endothelial cells increase the proliferation of Plasmodium falciparum through production of soluble factors.

    Science.gov (United States)

    Khaw, L T; Ball, H J; Mitchell, A J; Grau, G E; Stocker, R; Golenser, J; Hunt, N H

    2014-10-01

    We here describe the novel finding that brain endothelial cells in vitro can stimulate the growth of Plasmodium falciparum through the production of low molecular weight growth factors. By using a conditioned medium approach, we show that the brain endothelial cells continued to release these factors over time. If this mirrors the in vivo situation, these growth factors potentially would provide an advantage, in terms of enhanced growth, for sequestered parasitised red blood cells in the brain microvasculature. We observed this phenomenon with brain endothelial cells from several sources as well as a second P. falciparum strain. The characteristics of the growth factors included: heat stable, and in part chloroform soluble. Future efforts should be directed at identifying these growth factors, since blocking their production or actions might be of benefit for reducing parasite load and, hence, malaria pathology.

  14. 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...

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

    Directory of Open Access Journals (Sweden)

    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.

  16. 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...

  17. Licochalcone A, a new antimalarial agent, inhibits in vitro growth of the human malaria parasite Plasmodium falciparum and protects mice from em>P. yoelii infection

    DEFF Research Database (Denmark)

    Chen, M; Theander, T G; Christensen, S B;

    1994-01-01

    Licochalcone A, isolated from Chinese licorice roots, inhibited the in vitro growth of both chloroquine-susceptible (3D7) and chloroquine-resistant (Dd2) Plasmodium falciparum strains in a [3H]hypoxanthine uptake assay. The growth inhibition of the chloroquine-resistant strain by licochalcone A w...

  18. Comparative population structure of Plasmodium malariae and Plasmodium falciparum under different transmission settings in Malawi

    Directory of Open Access Journals (Sweden)

    Molyneux Malcolm E

    2011-02-01

    Full Text Available Abstract Background Described here is the first population genetic study of Plasmodium malariae, the causative agent of quartan malaria. Although not as deadly as Plasmodium falciparum, P. malariae is more common than previously thought, and is frequently in sympatry and co-infection with P. falciparum, making its study increasingly important. This study compares the population parameters of the two species in two districts of Malawi with different malaria transmission patterns - one seasonal, one perennial - to explore the effects of transmission on population structures. Methods Six species-specific microsatellite markers were used to analyse 257 P. malariae samples and 257 P. falciparum samples matched for age, gender and village of residence. Allele sizes were scored to within 2 bp for each locus and haplotypes were constructed from dominant alleles in multiple infections. Analysis of multiplicity of infection (MOI, population differentiation, clustering of haplotypes and linkage disequilibrium was performed for both species. Regression analyses were used to determine association of MOI measurements with clinical malaria parameters. Results Multiple-genotype infections within each species were common in both districts, accounting for 86.0% of P. falciparum and 73.2% of P. malariae infections and did not differ significantly with transmission setting. Mean MOI of P. falciparum was increased under perennial transmission compared with seasonal (3.14 vs 2.59, p = 0.008 and was greater in children compared with adults. In contrast, P. malariae mean MOI was similar between transmission settings (2.12 vs 2.11 and there was no difference between children and adults. Population differentiation showed no significant differences between villages or districts for either species. There was no evidence of geographical clustering of haplotypes. Linkage disequilibrium amongst loci was found only for P. falciparum samples from the seasonal transmission

  19. 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.

  20. Role and Regulation of Glutathione Metabolism in Plasmodium falciparum

    Directory of Open Access Journals (Sweden)

    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.

  1. Protection against Plasmodium falciparum malaria by PfSPZ Vaccine

    Science.gov (United States)

    Epstein, Judith E.; Paolino, Kristopher M.; Richie, Thomas L.; Sedegah, Martha; Singer, Alexandra; Ruben, Adam J.; Chakravarty, Sumana; Stafford, April; Ruck, Richard C.; Eappen, Abraham G.; Billingsley, Peter F.; Manoj, Anita; Moser, Kara; Nielsen, Robin; Tosh, Donna; Cicatelli, Susan; Ganeshan, Harini; Case, Jessica; Padilla, Debbie; Davidson, Silas; Saverino, Elizabeth; Murshedkar, Tooba; Gunasekera, Anusha; Twomey, Patrick S.; Reyes, Sharina; Moon, James E.; James, Eric R.; KC, Natasha; Li, Minglin; Abot, Esteban; Belmonte, Arnel; Hauns, Kevin; Belmonte, Maria; Huang, Jun; Vasquez, Carlos; Remich, Shon; Carrington, Mary; Abebe, Yonas; Tillman, Amy; Hickey, Bradley; Regules, Jason; Villasante, Eileen; Sim, B. Kim Lee

    2017-01-01

    BACKGROUND: A radiation-attenuated Plasmodium falciparum (Pf) sporozoite (SPZ) malaria vaccine, PfSPZ Vaccine, protected 6 of 6 subjects (100%) against homologous Pf (same strain as in the vaccine) controlled human malaria infection (CHMI) 3 weeks after 5 doses administered intravenously. The next step was to assess protective efficacy against heterologous Pf (different from Pf in the vaccine), after fewer doses, and at 24 weeks. METHODS: The trial assessed tolerability, safety, immunogenicity, and protective efficacy of direct venous inoculation (DVI) of 3 or 5 doses of PfSPZ Vaccine in non-immune subjects. RESULTS: Three weeks after final immunization, 5 doses of 2.7 × 105 PfSPZ protected 12 of 13 recipients (92.3% [95% CI: 48.0, 99.8]) against homologous CHMI and 4 of 5 (80.0% [10.4, 99.5]) against heterologous CHMI; 3 doses of 4.5 × 105 PfSPZ protected 13 of 15 (86.7% [35.9, 98.3]) against homologous CHMI. Twenty-four weeks after final immunization, the 5-dose regimen protected 7 of 10 (70.0% [17.3, 93.3]) against homologous and 1 of 10 (10.0% [–35.8, 45.6]) against heterologous CHMI; the 3-dose regimen protected 8 of 14 (57.1% [21.5, 76.6]) against homologous CHMI. All 22 controls developed Pf parasitemia. PfSPZ Vaccine was well tolerated, safe, and easy to administer. No antibody or T cell responses correlated with protection. CONCLUSIONS: We have demonstrated for the first time to our knowledge that PfSPZ Vaccine can protect against a 3-week heterologous CHMI in a limited group of malaria-naive adult subjects. A 3-dose regimen protected against both 3-week and 24-week homologous CHMI (87% and 57%, respectively) in this population. These results provide a foundation for developing an optimized immunization regimen for preventing malaria. TRIAL REGISTRATION: ClinicalTrials.gov NCT02215707. FUNDING: Support was provided through the US Army Medical Research and Development Command, Military Infectious Diseases Research Program, and the Naval Medical Research

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

    Directory of Open Access Journals (Sweden)

    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. Synthesis, biological evaluation and structure-activity relationships of new quinoxaline derivatives as anti-Plasmodium falciparum agents

    OpenAIRE

    Gil, Ana Gloria; Pabón, Adriana; Galiano, Silvia; Burguete, M. Isabel; Pérez-Silanes, Silvia; Deharo, Eric; Monge, Antonio; Aldana Ignacio

    2014-01-01

    We report the synthesis and antimalarial activities of eighteen quinoxaline and quinoxaline 1,4-di-N-oxide derivatives, eight of which are completely novel. Compounds 1a and 2a were the most active against Plasmodium falciparum strains. Structure-activity relationships demonstrated the importance of an enone moiety linked to the quinoxaline ring. © 2014 by the authors; licensee MDPI, Basel, Switzerland.

  4. Binding of Plasmodium falciparum to CD36 can be shielded by the glycocalyx

    DEFF Research Database (Denmark)

    Hempel, Casper; Wang, Christian William; Kurtzhals, Jorgen Anders Lindholm

    2017-01-01

    Background: Plasmodium falciparum-infected erythrocytes sequester in the microcirculation due to interaction between surface-expressed parasite proteins and endothelial receptors. Endothelial cells are covered in a carbohydrate-rich glycocalyx that shields against undesired leukocyte adhesion...

  5. 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...

  6. Longevity and composition of cellular immune responses following experimental Plasmodium falciparum malaria infection in humans.

    NARCIS (Netherlands)

    Teirlinck, A.C.; McCall, M.B.B.; Roestenberg, M.; Scholzen, A.; Woestenenk, R.M.; Mast, Q. de; Ven, A.J.A.M. van der; Hermsen, C.C.; Luty, A.J.F.; Sauerwein, R.W.

    2011-01-01

    Cellular responses to Plasmodium falciparum parasites, in particular interferon-gamma (IFNgamma) production, play an important role in anti-malarial immunity. However, clinical immunity to malaria develops slowly amongst naturally exposed populations, the dynamics of cellular responses in relation

  7. Drug resistance to sulphadoxine-pyrimethamine in Plasmodium falciparum malaria in Mlimba, Tanzania

    NARCIS (Netherlands)

    Mbugi, E.V.; Mutayoba, B.M.; Malisa, A.L.; Balthazary, S.T.; Nyambo, T.B.; Mshinda, H.

    2006-01-01

    Background - Sulphadoxine-pyrimethamine (SP) has been and is currently used for treatment of uncomplicated Plasmodium falciparum malaria in many African countries. Nevertheless, the response of parasites to SP treatment has shown significant variation between individuals. Methods - The genes for

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

    NARCIS (Netherlands)

    Tran, T.M.; Jones, M.B.; Ongoiba, A.; Bijker, E.M.; Schats, R.; Venepally, P.; Skinner, J.; Doumbo, S.; Quinten, E.; Visser, L.G.; Whalen, E.; Presnell, S.; O'Connell, E.M.; Kayentao, K.; Doumbo, O.K.; Chaussabel, D.; Lorenzi, H.; Nutman, T.B.; Ottenhoff, T.H.; Haks, M.C.; Traore, B.; Kirkness, E.F.; Sauerwein, R.W.; Crompton, P.D.

    2016-01-01

    Identifying molecular predictors and mechanisms of malaria disease is important for understanding how Plasmodium falciparum malaria is controlled. Transcriptomic studies in humans have so far been limited to retrospective analysis of blood samples from clinical cases. In this prospective,

  9. Reducing Plasmodium falciparum malaria transmission in Africa: a model-based evaluation of intervention strategies

    National Research Council Canada - National Science Library

    Griffin, Jamie T; Hollingsworth, T Deirdre; Okell, Lucy C; Churcher, Thomas S; White, Michael; Hinsley, Wes; Bousema, Teun; Drakeley, Chris J; Ferguson, Neil M; Basáñez, María-Gloria; Ghani, Azra C

    2010-01-01

    .... We developed an individual-based simulation model for Plasmodium falciparum transmission in an African context incorporating the three major vector species (Anopheles gambiae s.s., An. arabiensis, and An. funestus...

  10. 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...

  11. 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.

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

    Science.gov (United States)

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

    1985-11-01

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

  13. Complement receptor 1 is a sialic acid-independent erythrocyte receptor of Plasmodium falciparum.

    Directory of Open Access Journals (Sweden)

    Carmenza Spadafora

    Full Text Available Plasmodium falciparum is a highly lethal malaria parasite of humans. A major portion of its life cycle is dedicated to invading and multiplying inside erythrocytes. The molecular mechanisms of erythrocyte invasion are incompletely understood. P. falciparum depends heavily on sialic acid present on glycophorins to invade erythrocytes. However, a significant proportion of laboratory and field isolates are also able to invade erythrocytes in a sialic acid-independent manner. The identity of the erythrocyte sialic acid-independent receptor has been a mystery for decades. We report here that the complement receptor 1 (CR1 is a sialic acid-independent receptor for the invasion of erythrocytes by P. falciparum. We show that soluble CR1 (sCR1 as well as polyclonal and monoclonal antibodies against CR1 inhibit sialic acid-independent invasion in a variety of laboratory strains and wild isolates, and that merozoites interact directly with CR1 on the erythrocyte surface and with sCR1-coated microspheres. Also, the invasion of neuraminidase-treated erythrocytes correlates with the level of CR1 expression. Finally, both sialic acid-independent and dependent strains invade CR1 transgenic mouse erythrocytes preferentially over wild-type erythrocytes but invasion by the latter is more sensitive to neuraminidase. These results suggest that both sialic acid-dependent and independent strains interact with CR1 in the normal red cell during the invasion process. However, only sialic acid-independent strains can do so without the presence of glycophorin sialic acid. Our results close a longstanding and important gap in the understanding of the mechanism of erythrocyte invasion by P. falciparum that will eventually make possible the development of an effective blood stage vaccine.

  14. In vivo resistance to chloroquine by Plasmodium vivax and Plasmodium falciparum at Nabire, Irian Jaya, Indonesia.

    Science.gov (United States)

    Baird, J K; Wiady, I; Fryauff, D J; Sutanihardja, M A; Leksana, B; Widjaya, H; Kysdarmanto; Subianto, B

    1997-06-01

    A survey of resistance to chloroquine by Plasmodium vivax and P. falciparum was conducted during May 1995 at three mesoendemic villages 30 km southeast of Nabire, near the central northern coast of Irian Jaya, Indonesia. The prevalence of malaria at Urusumu (n = 157), Margajaya (n = 573), and Topo (n = 199) was 18%. 9%, and 9%, respectively, with spleen rates among children of 79%, 10%, and 27%. Infected patients among those screened formed a study population of 64 subjects eligible for a 28-day in vivo test of resistance to chloroquine. Sixty-three patients successfully completed the test; 45 males and 18 females 1-60 years of age, of whom 29 were Javanese transmigrants of five years residence in Irian Jaya and 34 were native to Irian Jaya. The seven-day day cumulative incidence of therapeutic failure for P. vivax and P. falciparum was 15% (n = 34) and 30% (n = 37). The 14- and 28-day estimates of cumulative incidence were 45% and 64% for P. vivax and 58% and 89% for P. falciparum. Almost all recurrences appeared in the face of ordinarily effective levels of chloroquine and its major metabolite, desethylchloroquine, in whole blood (> or = 100 ng/ml). Four infections by P. malariae in subjects enrolled in this study cleared by day 2 and none reappeared within 28 days. Chloroquine no longer provides effective therapy for falciparum or vivax malaria along the northern coast of Irian Jaya, Indonesia.

  15. MOLECULAR SURVEILLANCE OF Plasmodium vivax AND Plasmodium falciparum DHFR MUTATIONS IN ISOLATES FROM SOUTHERN IRAN.

    Science.gov (United States)

    Sharifi-Sarasiabi, Khojasteh; Haghighi, Ali; Kazemi, Bahram; Taghipour, Niloofar; Mojarad, Ehsan Nazemalhosseini; Gachkar, Latif

    2016-01-01

    In Iran, both Plasmodium vivax and P. falciparum malaria have been detected, but P. vivax is the predominant species. Point mutations in dihydrofolate reductase (dhfr) gene in both Plasmodia are the major mechanisms of pyrimethamine resistance. From April 2007 to June 2009, a total of 134 blood samples in two endemic areas of southern Iran were collected from patients infected with P. vivax and P. falciparum. The isolates were analyzed for P. vivax dihydrofolate reductase (pvdhfr) and P. falciparum dihydrofolate reductase (pfdhfr) point mutations using various PCR-based methods. The majority of the isolates (72.9%) had wild type amino acids at five codons of pvdhfr. Amongst mutant isolates, the most common pvdhfr alleles were double mutant in 58 and 117 amino acids (58R-117N). Triple mutation in 57, 58, and 117 amino acids (57L/58R/117N) was identified for the first time in the pvdhfr gene of Iranian P. vivax isolates. All the P. falciparumsamples analyzed (n = 16) possessed a double mutant pfdhfrallele (59R/108N) and retained a wild-type mutation at position 51. This may be attributed to the fact that the falciparum malaria patients were treated using sulfadoxine-pyrimethamine (SP) in Iran. The presence of mutant haplotypes in P. vivax is worrying, but has not yet reached an alarming threshold regarding drugs such as SP. The results of this study reinforce the importance of performing a molecular surveillance by means of a continuous chemoresistance assessment.

  16. 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....

  17. Origins and spread of pfdhfr mutant alleles in Plasmodium falciparum.

    Science.gov (United States)

    Mita, Toshihiro

    2010-06-01

    The emergence and spread of Plasmodium falciparum parasite resistant to sulfadoxine and pyrimethamine (SP) poses a serious public health problem. Resistance is caused by point mutations in dihydrofolate reductase (pfdhfr) and dihydropteroate synthase (pfdhps), the two key enzymes in the folate biosynthetic pathway. The use of microsatellite markers flanking pfdhfr has recently shown that the invasion of limited resistant lineages may explain the widespread SP resistance in many endemic regions. In Africa, however, multiple indigenous origins of pfdhfr triple mutants have been demonstrated. More new independent lineages and routes of geographical spread of resistance may be found by further molecular evolutionary analyses using samples from various endemic regions. Here, I review recent studies about the history of SP usage and the evolution and spread of resistant lineages while addressing the technical issue of microsatellite analysis.

  18. 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.

  19. Plasmodium falciparum full life cycle and Plasmodium ovale liver stages in humanized mice

    Science.gov (United States)

    Soulard, Valérie; Bosson-Vanga, Henriette; Lorthiois, Audrey; Roucher, Clémentine; Franetich, Jean- François; Zanghi, Gigliola; Bordessoulles, Mallaury; Tefit, Maurel; Thellier, Marc; Morosan, Serban; Le Naour, Gilles; Capron, Frédérique; Suemizu, Hiroshi; Snounou, Georges; Moreno-Sabater, Alicia; Mazier, Dominique

    2015-01-01

    Experimental studies of Plasmodium parasites that infect humans are restricted by their host specificity. Humanized mice offer a means to overcome this and further provide the opportunity to observe the parasites in vivo. Here we improve on previous protocols to achieve efficient double engraftment of TK-NOG mice by human primary hepatocytes and red blood cells. Thus, we obtain the complete hepatic development of P. falciparum, the transition to the erythrocytic stages, their subsequent multiplication, and the appearance of mature gametocytes over an extended period of observation. Furthermore, using sporozoites derived from two P. ovale-infected patients, we show that human hepatocytes engrafted in TK-NOG mice sustain maturation of the liver stages, and the presence of late-developing schizonts indicate the eventual activation of quiescent parasites. Thus, TK-NOG mice are highly suited for in vivo observations on the Plasmodium species of humans. PMID:26205537

  20. Plasmodium vivax and Plasmodium falciparum are Common Malaria Species in Pakistan

    Directory of Open Access Journals (Sweden)

    Tauseef Ahmad

    2016-06-01

    Full Text Available The microbes have a diverse nature, it makes human laugh and cry. Some microbes are fruitful for humans while others are harmful. Infectious diseases are a key problem in the modern world. In the last few decades, million of peoples have died from different diseases, including bacterial, viral, fungal, parasitic, etc. Among these diseases, malaria is one of the major health problems for developing countries including Pakistan. This study was undertaken to provide baseline information about the prevalence of malaria, species distribution and to contribute to the data regarding epidemiology in Pakistan. For a collection of literature, the electronic search engine was used, using different key words i.e. prevalence, species distribution, epidemiology of malaria in Pakistan, etc. The time frame of the obtained articles was from 2000 to 2014. The two species of malaria Plasmodium vivax and Plasmodium falciparum are common in Pakistan. [Biomed Res Ther 2016; 3(6.000: 666-672

  1. 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 ...

  2. Lack of Evidence for Chloroquine-Resistant Plasmodium falciparum Malaria, Leogane, Haiti

    Science.gov (United States)

    Neuberger, Ami; Zhong, Kathleen; Kain, Kevin C

    2012-01-01

    Plasmodium falciparum malaria in Haiti is considered chloroquine susceptible, although resistance transporter alleles associated with chloroquine resistance were recently detected. Among 49 patients with falciparum malaria, we found neither parasites carrying haplotypes associated with chloroquine resistance nor instances of chloroquine treatment failure. Continued vigilance to detect emergence of chloroquine resistance is needed. PMID:22932030

  3. 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...

  4. Lymphocyte response to purified Plasmodium falciparum antigens during and after malaria

    DEFF Research Database (Denmark)

    Bygbjerg, I C; Jepsen, S; Theander, T G

    1986-01-01

    The peripheral blood lymphocyte response to affinity purified soluble Plasmodium falciparum antigens from in vitro cultures was studied in seven patients with acute falciparum malaria, on eight occasions, and in 15 persons having had malaria, at various times post infection, on 24 occasions. During...

  5. Lack of evidence for chloroquine-resistant Plasmodium falciparum malaria, Leogane, Haiti.

    Science.gov (United States)

    Neuberger, Ami; Zhong, Kathleen; Kain, Kevin C; Schwartz, Eli

    2012-09-01

    Plasmodium falciparum malaria in Haiti is considered chloroquine susceptible, although resistance transporter alleles associated with chloroquine resistance were recently detected. Among 49 patients with falciparum malaria, we found neither parasites carrying haplotypes associated with chloroquine resistance nor instances of chloroquine treatment failure. Continued vigilance to detect emergence of chloroquine resistance is needed.

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

    NARCIS (Netherlands)

    Breitling, L.P.; Fendel, R.; Mordmueller, B.; Adegnika, A.A.; Kremsner, P.G.; Luty, A.J.F.

    2006-01-01

    Placental Plasmodium falciparum infection affects birth outcomes and sensitizes fetal lymphocytes to parasite antigens. We assessed the influence of maternal P. falciparum infection on fetal myeloid dendritic cells (mDC) and plasmacytoid dendritic cells (pDC), analyzing the cord blood of offspring o

  7. 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

  8. A new world malaria map: Plasmodium falciparum endemicity in 2010

    Directory of Open Access Journals (Sweden)

    Gething Peter W

    2011-12-01

    Full Text Available Abstract Background Transmission intensity affects almost all aspects of malaria epidemiology and the impact of malaria on human populations. Maps of transmission intensity are necessary to identify populations at different levels of risk and to evaluate objectively options for disease control. To remain relevant operationally, such maps must be updated frequently. Following the first global effort to map Plasmodium falciparum malaria endemicity in 2007, this paper describes the generation of a new world map for the year 2010. This analysis is extended to provide the first global estimates of two other metrics of transmission intensity for P. falciparum that underpin contemporary questions in malaria control: the entomological inoculation rate (PfEIR and the basic reproductive number (PfR. Methods Annual parasite incidence data for 13,449 administrative units in 43 endemic countries were sourced to define the spatial limits of P. falciparum transmission in 2010 and 22,212 P. falciparum parasite rate (PfPR surveys were used in a model-based geostatistical (MBG prediction to create a continuous contemporary surface of malaria endemicity within these limits. A suite of transmission models were developed that link PfPR to PfEIR and PfR and these were fitted to field data. These models were combined with the PfPR map to create new global predictions of PfEIR and PfR. All output maps included measured uncertainty. Results An estimated 1.13 and 1.44 billion people worldwide were at risk of unstable and stable P. falciparum malaria, respectively. The majority of the endemic world was predicted with a median PfEIR of less than one and a median PfRc of less than two. Values of either metric exceeding 10 were almost exclusive to Africa. The uncertainty described in both PfEIR and PfR was substantial in regions of intense transmission. Conclusions The year 2010 has a particular significance as an evaluation milestone for malaria global health policy. The

  9. Glycerol inhibits water permeation through Plasmodium falciparum aquaglyceroporin.

    Science.gov (United States)

    Chen, Liao Y

    2013-01-01

    Plasmodium falciparum aquaglyceroporin (PfAQP) is a multifunctional membrane protein in the plasma membrane of P. falciparum, the parasite that causes the most severe form of malaria. The current literature has established the science of PfAQP's structure, functions, and hydrogen-bonding interactions but left unanswered the following fundamental question: does glycerol modulate water permeation through aquaglyceroporin that conducts both glycerol and water? This paper provides an affirmative answer to this question of essential importance to the protein's functions. On the basis of the chemical-potential profile of glycerol from the extracellular bulk region, throughout PfAQP's conducting channel, to the cytoplasmic bulk region, this study shows the existence of a bound state of glycerol inside aquaglyceroporin's permeation pore, from which the dissociation constant is approximately 14μM. A glycerol molecule occupying the bound state occludes the conducting pore through which permeating molecules line up in single file by hydrogen-bonding with one another and with the luminal residues of aquaglyceroporin. In this way, glycerol inhibits permeation of water and other permeants through aquaglyceroporin. The biological implications of this theory are discussed and shown to agree with the existent in vitro data. It turns out that the structure of aquaglyceroporin is perfect for the van der Waals interactions between the protein and glycerol to cause the existence of the bound state deep inside the conducting pore and, thus to play an unexpected but significant role in aquaglyceroporin's functions.

  10. Molecular Aspects of Plasmodium falciparum Infection during Pregnancy

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    Nicaise Tuikue Ndam

    2007-01-01

    Full Text Available Cytoadherence of Plasmodium-falciparum-parasitized red blood cells (PRBCs to host receptors is the key phenomenon in the pathological process of the malaria disease. Some of these interactions can originate poor outcomes responsible for 1 to 3 million annual deaths mostly occurring among children in sub-Saharan Africa. Pregnancy-associated malaria (PAM represents an important exception of the disease occurring at adulthood in malaria endemic settings. Consequences of this are shared between the mother (maternal anemia and the baby (low birth weight and infant mortality. Demonstrating that parasites causing PAM express specific variant surface antigens (VSAPAM, including the P. falciparum erythrocyte membrane protein 1 (PfEMP1 variant VAR2CSA, that are targets for protective immunity has strengthened the possibility for the development of PAM-specific vaccine. In this paper, we review the molecular basis of malaria pathogenesis attributable to the erythrocyte stages of the parasites, and findings supporting potential anti-PAM vaccine components evidenced in PAM.

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

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    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.

  12. Targeting glycolysis in the malaria parasite Plasmodium falciparum.

    Science.gov (United States)

    van Niekerk, David D; Penkler, Gerald P; du Toit, Francois; Snoep, Jacky L

    2016-02-01

    Glycolysis is the main pathway for ATP production in the malaria parasite Plasmodium falciparum and essential for its survival. Following a sensitivity analysis of a detailed kinetic model for glycolysis in the parasite, the glucose transport reaction was identified as the step whose activity needed to be inhibited to the least extent to result in a 50% reduction in glycolytic flux. In a subsequent inhibitor titration with cytochalasin B, we confirmed the model analysis experimentally and measured a flux control coefficient of 0.3 for the glucose transporter. In addition to the glucose transporter, the glucokinase and phosphofructokinase had high flux control coefficients, while for the ATPase a small negative flux control coefficient was predicted. In a broader comparative analysis of glycolytic models, we identified a weakness in the P. falciparum pathway design with respect to stability towards perturbations in the ATP demand. The mathematical model described here has been submitted to the JWS Online Cellular Systems Modelling Database and can be accessed at http://jjj.bio.vu.nl/database/vanniekerk1. The SEEK-study including the experimental data set is available at DOI 10.15490/seek.1. 56 (http://dx.doi.org/10.15490/seek.1. 56). © 2015 FEBS.

  13. Atorvastatin prevents Plasmodium falciparum cytoadherence and endothelial damage

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    Soubrier Florent

    2011-02-01

    Full Text Available Abstract Background The adhesion of Plasmodium falciparum parasitized red blood cell (PRBC to human endothelial cells (EC induces inflammatory processes, coagulation cascades, oxidative stress and apoptosis. These pathological processes are suspected to be responsible for the blood-brain-barrier and other organs' endothelial dysfunctions observed in fatal cases of malaria. Atorvastatin, a drug that belongs to the lowering cholesterol molecule family of statins, has been shown to ameliorate endothelial functions and is widely used in patients with cardiovascular disorders. Methods The effect of this compound on PRBC induced endothelial impairments was assessed using endothelial co-culture models. Results Atorvastatin pre-treatment of EC was found to reduce the expression of adhesion molecules and P. falciparum cytoadherence, to protect cells against PRBC-induced apoptosis and to enhance endothelial monolayer integrity during co-incubation with parasites. Conclusions These results might suggest a potential interest use of atorvastatin as a protective treatment to interfere with the pathophysiological cascades leading to severe malaria.

  14. 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.

  15. Mitotic evolution of Plasmodium falciparum shows a stable core genome but recombination in antigen families.

    Directory of Open Access Journals (Sweden)

    Selina E R Bopp

    Full Text Available Malaria parasites elude eradication attempts both within the human host and across nations. At the individual level, parasites evade the host immune responses through antigenic variation. At the global level, parasites escape drug pressure through single nucleotide variants and gene copy amplification events conferring drug resistance. Despite their importance to global health, the rates at which these genomic alterations emerge have not been determined. We studied the complete genomes of different Plasmodium falciparum clones that had been propagated asexually over one year in the presence and absence of drug pressure. A combination of whole-genome microarray analysis and next-generation deep resequencing (totaling 14 terabases revealed a stable core genome with only 38 novel single nucleotide variants appearing in seventeen evolved clones (avg. 5.4 per clone. In clones exposed to atovaquone, we found cytochrome b mutations as well as an amplification event encompassing the P. falciparum multidrug resistance associated protein (mrp1 on chromosome 1. We observed 18 large-scale (>1 kb on average deletions of telomere-proximal regions encoding multigene families, involved in immune evasion (9.5×10(-6 structural variants per base pair per generation. Six of these deletions were associated with chromosomal crossovers generated during mitosis. We found only minor differences in rates between genetically distinct strains and between parasites cultured in the presence or absence of drug. Using these derived mutation rates for P. falciparum (1.0-9.7×10(-9 mutations per base pair per generation, we can now model the frequency at which drug or immune resistance alleles will emerge under a well-defined set of assumptions. Further, the detection of mitotic recombination events in var gene families illustrates how multigene families can arise and change over time in P. falciparum. These results will help improve our understanding of how P. falciparum

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

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    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

  17. Exitoso cultivo in vitro de gametocitos de Plasmodium falciparum

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    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.

  18. Fatal Plasmodium falciparum, Clostridium perfringens, and Candida spp. Coinfections in a Traveler to Haiti

    Science.gov (United States)

    Genrich, Gillian L.; Bhatnagar, Julu; Paddock, Christopher D.; Zaki, Sherif R.

    2009-01-01

    Malaria is one of the most common causes of febrile illness in travelers. Coinfections with bacterial, viral, and fungal pathogens may not be suspected unless a patient fails to respond to malaria treatment. Using novel immunohistochemical and molecular techniques, Plasmodium falciparum, Clostridium perfringens, and Candida spp. coinfections were confirmed in a German traveler to Haiti. Plasmodium falciparum-induced ischemia may have increased this patient's susceptibility to C. perfringens and disseminated candidiasis leading to his death. When a patient presents with P. falciparum and shock and is unresponsive to malaria treatment, secondary infections should be suspected to initiate appropriate treatment. PMID:20339463

  19. Dual fluorescent labelling of the human malaria parasite Plasmodium falciparum for the analysis of the ABC type transporter pfmdr2.

    Science.gov (United States)

    Rosental, Benyamin; Hadad, Uzi; Sinay, Rosa; Braiman, Alex; Porgador, Angel; Pollack, Yaakov

    2012-11-08

    The study of the Plasmodium falciparum heavy metal transporter gene pfmdr2 employed radioactive labelled heavy metal. As the use of radioactive isotopes shrank considerably during the last few years, resulting in the cessation of the production of some isotopes, amongst them Cadmium109 which was used for that purpose, a different approach had to be developed. Herein, a dual fluorescent labelling of heavy metals accumulation in the P. falciparum parasite is proposed as an alternative to the use of radioactive labelled heavy metals. Plasmodium falciparum Cd resistant and sensitive strains at the trophozoite stage were used in this study. The cells were cultured at different CdCl2 concentrations and for different time periods followed by staining of the infected red blood cells with Fluo-3/AM for Cd detection and Hoechst 33342 for parasite DNA labelling. The fluorescent analysis was done by flow cytometry and confocal microscopy. The results show that the sensitive strain has a higher Fluo-3/AM fluorescence in a Cd concentration and time dependent manner, whereas in the resistant strain Fluo-3/AM fluorescence levels were negligible and increased only at high concentrations of Cd and at long incubation periods, but to a much lesser extent than the sensitive strain. No Cd uptake is observed in uninfected red blood cells populations originating from cultures infected with either sensitive or resistant strain. In addition, confocal microscopy overlay of Fluo-3/AM and Hoechst staining shows that the Cd metal accumulates in the parasite itself. The dual fluorescent labelling is a valid method for detecting heavy metal accumulation in P. falciparum. Furthermore, in contrast to the use of radioactive labelled heavy metal, the fluorescent labelling enables us to differentiate between the different populations existing in a P. falciparum infected red blood cells cultures and thus actually study a phenomenon at the level of a single cell.

  20. Dual fluorescent labelling of the human malaria parasite Plasmodium falciparum for the analysis of the ABC type transporter pfmdr2

    Directory of Open Access Journals (Sweden)

    Rosental Benyamin

    2012-11-01

    Full Text Available Abstract Background The study of the Plasmodium falciparum heavy metal transporter gene pfmdr2 employed radioactive labelled heavy metal. As the use of radioactive isotopes shrank considerably during the last few years, resulting in the cessation of the production of some isotopes, amongst them Cadmium109 which was used for that purpose, a different approach had to be developed. Herein, a dual fluorescent labelling of heavy metals accumulation in the P. falciparum parasite is proposed as an alternative to the use of radioactive labelled heavy metals. Methods Plasmodium falciparum Cd resistant and sensitive strains at the trophozoite stage were used in this study. The cells were cultured at different CdCl2 concentrations and for different time periods followed by staining of the infected red blood cells with Fluo-3/AM for Cd detection and Hoechst 33342 for parasite DNA labelling. The fluorescent analysis was done by flow cytometry and confocal microscopy. Results The results show that the sensitive strain has a higher Fluo-3/AM fluorescence in a Cd concentration and time dependent manner, whereas in the resistant strain Fluo-3/AM fluorescence levels were negligible and increased only at high concentrations of Cd and at long incubation periods, but to a much lesser extent than the sensitive strain. No Cd uptake is observed in uninfected red blood cells populations originating from cultures infected with either sensitive or resistant strain. In addition, confocal microscopy overlay of Fluo-3/AM and Hoechst staining shows that the Cd metal accumulates in the parasite itself. Conclusions The dual fluorescent labelling is a valid method for detecting heavy metal accumulation in P. falciparum. Furthermore, in contrast to the use of radioactive labelled heavy metal, the fluorescent labelling enables us to differentiate between the different populations existing in a P. falciparum infected red blood cells cultures and thus actually study a phenomenon at

  1. In vitro Potentiation of Antimalarial Activities by Daphnetin Derivatives Against Plasmodium falciparum

    Institute of Scientific and Technical Information of China (English)

    FANG HUANG; LIN-HUA TANG; LIN-QIAN YU; YI-CHANG NI; QIN-MEI WANG; FA-JUN NAN

    2006-01-01

    Objective To screen the antimalarial compounds of daphnetin derivatives against Plasmodium falciparum in vitro. Method Plasmodium faciparum (FCC1) was cultured in vitro by a modified method of Trager and Jensen. Antimalarial compounds were screened by microscopy-based assay and microfluorimetric method. Results DA79 and DA78 showed potent antimalarial activity against Plasmodium falciparum cultured in vitro. Conclusion Though the relationship between the structures of daphnetin derivatives and their antimalarial activities has not been clarified yet, this study may provide a new direction for discovery of more potential antimalarial compounds.

  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. Targeting protein translation, RNA splicing, and degradation by morpholino-based conjugates in Plasmodium falciparum.

    Science.gov (United States)

    Garg, Aprajita; Wesolowski, Donna; Alonso, Dulce; Deitsch, Kirk W; Ben Mamoun, Choukri; Altman, Sidney

    2015-09-22

    Identification and genetic validation of new targets from available genome sequences are critical steps toward the development of new potent and selective antimalarials. However, no methods are currently available for large-scale functional analysis of the Plasmodium falciparum genome. Here we present evidence for successful use of morpholino oligomers (MO) to mediate degradation of target mRNAs or to inhibit RNA splicing or translation of several genes of P. falciparum involved in chloroquine transport, apicoplast biogenesis, and phospholipid biosynthesis. Consistent with their role in the parasite life cycle, down-regulation of these essential genes resulted in inhibition of parasite development. We show that a MO conjugate that targets the chloroquine-resistant transporter PfCRT is effective against chloroquine-sensitive and -resistant parasites, causes enlarged digestive vacuoles, and renders chloroquine-resistant strains more sensitive to chloroquine. Similarly, we show that a MO conjugate that targets the PfDXR involved in apicoplast biogenesis inhibits parasite growth and that this defect can be rescued by addition of isopentenyl pyrophosphate. MO-based gene regulation is a viable alternative approach to functional analysis of the P. falciparum genome.

  5. The remarkable journey of adaptation of the Plasmodium falciparum malaria parasite to New World anopheline mosquitoes.

    Science.gov (United States)

    Molina-Cruz, Alvaro; Barillas-Mury, Carolina

    2014-08-01

    Plasmodium falciparum originated in Africa, dispersed around the world as a result of human migration and had to adapt to several different indigenous anopheline mosquitoes. Anophelines from the New World are evolutionary distant form African ones and this probably resulted in a more stringent selection of Plasmodium as it adapted to these vectors. It is thought that Plasmodium has been genetically selected by some anopheline species through unknown mechanisms. The mosquito immune system can greatly limit infection and P. falciparum evolved a strategy to evade these responses, at least in part mediated by Pfs47, a highly polymorphic gene. We propose that adaptation of P. falciparum to new vectors may require evasion of their immune system. Parasites with a Pfs47 haplotype compatible with the indigenous mosquito vector would be able to survive and be transmitted. The mosquito antiplasmodial response could be an important determinant of P. falciparum population structure and could affect malaria transmission in the Americas.

  6. The remarkable journey of adaptation of the Plasmodium falciparum malaria parasite to New World anopheline mosquitoes

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    Alvaro Molina-Cruz

    2014-08-01

    Full Text Available Plasmodium falciparum originated in Africa, dispersed around the world as a result of human migration and had to adapt to several different indigenous anopheline mosquitoes. Anophelines from the New World are evolutionary distant form African ones and this probably resulted in a more stringent selection of Plasmodium as it adapted to these vectors. It is thought that Plasmodium has been genetically selected by some anopheline species through unknown mechanisms. The mosquito immune system can greatly limit infection and P. falciparum evolved a strategy to evade these responses, at least in part mediated by Pfs47, a highly polymorphic gene. We propose that adaptation of P. falciparum to new vectors may require evasion of their immune system. Parasites with a Pfs47 haplotype compatible with the indigenous mosquito vector would be able to survive and be transmitted. The mosquito antiplasmodial response could be an important determinant of P. falciparum population structure and could affect malaria transmission in the Americas.

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

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    Myat P Kyaw

    Full Text Available BACKGROUND: 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. METHODS: 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. RESULTS: 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. CONCLUSIONS: A subset of P. falciparum infections in southern Myanmar displayed markedly delayed clearance following artemisinin treatment, suggesting either emergence of

  8. 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.; Tarning, Joel; Imwong, Mallika; Jacob, Christopher G.; Rasmussen, Charlotte; Perin, Jamie; Ringwald, Pascal; Nyunt, Myaing M.

    2013-01-01

    Background 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. Methods 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. Results 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. Conclusions A subset of P. falciparum infections in southern Myanmar displayed markedly delayed clearance following artemisinin treatment, suggesting either emergence of artemisinin

  9. Allelic Diversity of MSP1 Gene in Plasmodium falciparum from Rural and Urban Areas of Gabon.

    Science.gov (United States)

    Mawili-Mboumba, Denise Patricia; Mbondoukwe, Noé; Adande, Elvire; Bouyou-Akotet, Marielle Karine

    2015-08-01

    The present study determined and compared the genetic diversity of Plasmodium falciparum strains infecting children living in 2 areas from Gabon with different malaria endemicity. Blood samples were collected from febrile children from 2008 to 2009 in 2 health centres from rural (Oyem) and urban (Owendo) areas. Genetic diversity was determined in P. falciparum isolates by analyzing the merozoite surface protein-1 (msp1) gene polymorphism using nested-PCR. Overall, 168 children with mild falciparum malaria were included. K1, Ro33, and Mad20 alleles were found in 110 (65.5%), 94 (55.9%), and 35 (20.8%) isolates, respectively, without difference according to the site (P>0.05). Allelic families' frequencies were comparable between children less than 5 years old from the 2 sites; while among the older children the proportions of Ro33 and Mad20 alleles were 1.7 to 2.0 fold higher at Oyem. Thirty-three different alleles were detected, 16 (48.5%) were common to both sites, and 10 out of the 17 specific alleles were found at Oyem. Furthermore, multiple infection carriers were frequent at Oyem (57.7% vs 42.2% at Owendo; P=0.04) where the complexity of infection was of 1.88 (±0.95) higher compared to that found at Owendo (1.55±0.75). Extended genetic diversity of P. falciparum strains infecting Gabonese symptomatic children and high multiplicity of infections were observed in rural area. Alleles common to the 2 sites were frequent; the site-specific alleles predominated in the rural area. Such distribution of the alleles should be taken into accounts when designing MSP1 or MSP2 malaria vaccine.

  10. 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...

  11. Identification of Plasmodium falciparum DNA Repair Protein Mre11 with an Evolutionarily Conserved Nuclease Function.

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    Sugith Babu Badugu

    Full Text Available The eukaryotic Meiotic Recombination protein 11 (Mre11 plays pivotal roles in the DNA damage response (DDR. Specifically, Mre11 senses and signals DNA double strand breaks (DSB and facilitates their repair through effector proteins belonging to either homologous recombination (HR or non-homologous end joining (NHEJ repair mechanisms. In the human malaria parasite Plasmodium falciparum, HR and alternative-NHEJ have been identified; however, little is known about the upstream factors involved in the DDR of this organism. In this report, we identify a putative ortholog of Mre11 in P. falciparum (PfalMre11 that shares 22% sequence similarity to human Mre11. Homology modeling reveals striking structural resemblance of the predicted PfalMre11 nuclease domain to the nuclease domain of Saccharomyces cerevisiae Mre11 (ScMre11. Complementation analyses reveal functional conservation of PfalMre11 nuclease activity as demonstrated by the ability of the PfalMre11 nuclease domain, in conjunction with the C-terminal domain of ScMre11, to functionally complement an mre11 deficient yeast strain. Functional complementation was virtually abrogated by an amino acid substitution in the PfalMre11 nuclease domain (D398N. PfalMre11 is abundant in the mitotically active trophozoite and schizont stages of P. falciparum and is up-regulated in response to DNA damage, suggesting a role in the DDR. PfalMre11 exhibits physical interaction with PfalRad50. In addition, yeast 2-hybrid studies show that PfalMre11 interacts with ScRad50 and ScXrs2, two important components of the well characterized Mre11-Rad50-Xrs2 complex which is involved in DDR signaling and repair in S. cerevisiae, further supporting a role for PfalMre11 in the DDR. Taken together, these findings provide evidence that PfalMre11 is an evolutionarily conserved component of the DDR in Plasmodium.

  12. Identification of Plasmodium falciparum DNA Repair Protein Mre11 with an Evolutionarily Conserved Nuclease Function.

    Science.gov (United States)

    Badugu, Sugith Babu; Nabi, Shaik Abdul; Vaidyam, Pratap; Laskar, Shyamasree; Bhattacharyya, Sunanda; Bhattacharyya, Mrinal Kanti

    2015-01-01

    The eukaryotic Meiotic Recombination protein 11 (Mre11) plays pivotal roles in the DNA damage response (DDR). Specifically, Mre11 senses and signals DNA double strand breaks (DSB) and facilitates their repair through effector proteins belonging to either homologous recombination (HR) or non-homologous end joining (NHEJ) repair mechanisms. In the human malaria parasite Plasmodium falciparum, HR and alternative-NHEJ have been identified; however, little is known about the upstream factors involved in the DDR of this organism. In this report, we identify a putative ortholog of Mre11 in P. falciparum (PfalMre11) that shares 22% sequence similarity to human Mre11. Homology modeling reveals striking structural resemblance of the predicted PfalMre11 nuclease domain to the nuclease domain of Saccharomyces cerevisiae Mre11 (ScMre11). Complementation analyses reveal functional conservation of PfalMre11 nuclease activity as demonstrated by the ability of the PfalMre11 nuclease domain, in conjunction with the C-terminal domain of ScMre11, to functionally complement an mre11 deficient yeast strain. Functional complementation was virtually abrogated by an amino acid substitution in the PfalMre11 nuclease domain (D398N). PfalMre11 is abundant in the mitotically active trophozoite and schizont stages of P. falciparum and is up-regulated in response to DNA damage, suggesting a role in the DDR. PfalMre11 exhibits physical interaction with PfalRad50. In addition, yeast 2-hybrid studies show that PfalMre11 interacts with ScRad50 and ScXrs2, two important components of the well characterized Mre11-Rad50-Xrs2 complex which is involved in DDR signaling and repair in S. cerevisiae, further supporting a role for PfalMre11 in the DDR. Taken together, these findings provide evidence that PfalMre11 is an evolutionarily conserved component of the DDR in Plasmodium.

  13. A World Malaria Map: Plasmodium falciparum Endemicity in 2007

    Science.gov (United States)

    Hay, Simon I; Guerra, Carlos A; Gething, Peter W; Patil, Anand P; Tatem, Andrew J; Noor, Abdisalan M; Kabaria, Caroline W; Manh, Bui H; Elyazar, Iqbal R. F; Brooker, Simon; Smith, David L; Moyeed, Rana A; Snow, Robert W

    2009-01-01

    Background 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. Methods and Findings 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%). The vast majority (88%) of those living under stable risk in CSE Asia were also in this low endemicity class; a small remainder (11%) were in the intermediate endemicity class (PfPR2−10 > 5 to < 40%); and the remaining fraction (1%) in high endemicity (PfPR2−10 ≥ 40%) areas. High endemicity was widespread in the

  14. Biochemical and structural characterization of Plasmodium falciparum glutamate dehydrogenase 2.

    Science.gov (United States)

    Zocher, Kathleen; Fritz-Wolf, Karin; Kehr, Sebastian; Fischer, Marina; Rahlfs, Stefan; Becker, Katja

    2012-05-01

    Glutamate dehydrogenases (GDHs) play key roles in cellular redox, amino acid, and energy metabolism, thus representing potential targets for pharmacological interventions. Here we studied the functional network provided by the three known glutamate dehydrogenases of the malaria parasite Plasmodium falciparum. The recombinant production of the previously described PfGDH1 as hexahistidyl-tagged proteins was optimized. Additionally, PfGDH2 was cloned, recombinantly produced, and characterized. Like PfGDH1, PfGDH2 is an NADP(H)-dependent enzyme with a specific activity comparable to PfGDH1 but with slightly higher K(m) values for its substrates. The three-dimensional structure of hexameric PfGDH2 was solved to 3.1 Å resolution. The overall structure shows high similarity with PfGDH1 but with significant differences occurring at the subunit interface. As in mammalian GDH1, in PfGDH2 the subunit-subunit interactions are mainly assisted by hydrogen bonds and hydrophobic interactions, whereas in PfGDH1 these contacts are mediated by networks of salt bridges and hydrogen bonds. In accordance with this, the known bovine GDH inhibitors hexachlorophene, GW5074, and bithionol were more effective on PfGDH2 than on PfGDH1. Subcellular localization was determined for all three plasmodial GDHs by fusion with the green fluorescent protein. Based on our data, PfGDH1 and PfGDH3 are cytosolic proteins whereas PfGDH2 clearly localizes to the apicoplast, a plastid-like organelle specific for apicomplexan parasites. This study provides new insights into the structure and function of GDH isoenzymes of P. falciparum, which represent potential targets for the development of novel antimalarial drugs.

  15. The prognostic value of schizontaemia in imported Plasmodium falciparum malaria

    Science.gov (United States)

    2012-01-01

    Background In Plasmodium falciparum infection, peripheral parasite counts do not always correlate well with the sequestered parasite burden. As erythrocytes parasitized with mature trophozoites and schizonts have a high tendency to adhere to the microvascular endothelium, they are often absent in peripheral blood samples. The appearance of schizonts in peripheral blood smears is thought to be a marker of high sequestered parasite burden and severe disease. In the present study, the value of schizontaemia as an early marker for severe disease in non-immune individuals with imported malaria was evaluated. Methods All patients in the Rotterdam Malaria Cohort diagnosed with P. falciparum malaria between 1 January 1999 and 1 January 2012 were included. Thick and thin blood films were examined for the presence of schizontaemia. The occurrence of WHO defined severe malaria was the primary endpoint. The diagnostic performance of schizontaemia was compared with previously evaluated biomarkers C-reactive protein and lactate. Results Schizonts were present on admission in 49 of 401 (12.2%) patients. Patients with schizontaemia were more likely to present with severe malaria, a more complicated course and had longer duration of admission in hospital. Schizontaemia had a specificity of 0.95, a sensitivity of 0.53, a negative predictive value of 0.92 and a positive predictive value of 0.67 for severe malaria. The presence of schizonts was an independent predictor for severe malaria. Conclusion Absence of schizonts was found to be a specific marker for exclusion of severe malaria. Presence of schizonts on admission was associated with a high positive predictive value for severe malaria. This may be of help to identify patients who are at risk of a more severe course than would be expected when considering peripheral parasitaemia alone. PMID:22929647

  16. 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.

  17. Molecular characterisation of drug-resistant Plasmodium falciparum from Thailand

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    Gil José

    2002-10-01

    Full Text Available Abstract Background The increasing levels of Plasmodium falciparum resistance to chloroquine (CQ in Thailand have led to the use of alternative antimalarials, which are at present also becoming ineffective. In this context, any strategies that help improve the surveillance of drug resistance, become crucial in overcoming the problem. Methods In the present study, we have established the in vitro sensitivity to CQ, mefloquine (MF, quinine (QUIN and amodiaquine (AMQ of 52 P. falciparum isolates collected in Thailand, and assessed the prevalence of four putative genetic polymorphisms of drug resistance, pfcrt K76T, pfmdr1 N86Y, pfmdr1 D1042N and pfmdr1 Y1246D, by PCR-RFLP. Results The percentage of isolates resistant to CQ, MF, and AMQ was 96% (50/52, 62% (32/52, and 58% (18/31, respectively, while all parasites were found to be sensitive to QUIN. In addition, 41 (79% of the isolates assayed were resistant simultaneously to more than one drug; 25 to CQ and MF, 9 to CQ and AMQ, and 7 to all three drugs, CQ, MF and AMQ. There were two significant associations between drug sensitivity and presence of particular molecular markers, i CQ resistance / pfcrt 76T (P = 0.001, and ii MF resistance / pfmdr1 86N (P Conclusions i In Thailand, the high levels of CQ pressure have led to strong selection of the pfcrt 76T polymorphism and ii pfmdr1 86N appears to be a good predictor of in vitro MF resistance.

  18. Origin and evolution of sulfadoxine resistant Plasmodium falciparum.

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    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

  19. Origin and evolution of sulfadoxine resistant Plasmodium falciparum.

    Science.gov (United States)

    Vinayak, Sumiti; Alam, Md Tauqeer; 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

    2010-03-26

    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.

  20. Spatial prediction of Plasmodium falciparum prevalence in Somalia

    Directory of Open Access Journals (Sweden)

    Shewchuk Tanya

    2008-08-01

    Full Text Available Abstract Background Maps of malaria distribution are vital for optimal allocation of resources for anti-malarial activities. There is a lack of reliable contemporary malaria maps in endemic countries in sub-Saharan Africa. This problem is particularly acute in low malaria transmission countries such as those located in the horn of Africa. Methods Data from a national malaria cluster sample survey in 2005 and routine cluster surveys in 2007 were assembled for Somalia. Rapid diagnostic tests were used to examine the presence of Plasmodium falciparum parasites in finger-prick blood samples obtained from individuals across all age-groups. Bayesian geostatistical models, with environmental and survey covariates, were used to predict continuous maps of malaria prevalence across Somalia and to define the uncertainty associated with the predictions. Results For analyses the country was divided into north and south. In the north, the month of survey, distance to water, precipitation and temperature had no significant association with P. falciparum prevalence when spatial correlation was taken into account. In contrast, all the covariates, except distance to water, were significantly associated with parasite prevalence in the south. The inclusion of covariates improved model fit for the south but not for the north. Model precision was highest in the south. The majority of the country had a predicted prevalence of Conclusion The maps showed that malaria transmission in Somalia varied from hypo- to meso-endemic. However, even after including the selected covariates in the model, there still remained a considerable amount of unexplained spatial variation in parasite prevalence, indicating effects of other factors not captured in the study. Nonetheless the maps presented here provide the best contemporary information on malaria prevalence in Somalia.

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

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    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.

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

    Science.gov (United States)

    Gardner, Kate B; Sinha, Ipsita; Bustamante, Leyla Y; Day, Nicholas Pj; White, Nicholas J; Woodrow, Charles J

    2011-09-14

    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. 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. Coding sequences of malaria parasites contain prospectively definable domains subject to neutral or nearly

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

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    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

  4. Protease-associated cellular networks in malaria parasite Plasmodium falciparum

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    Lilburn Timothy G

    2011-12-01

    Full Text Available Abstract Background Malaria continues to be one of the most severe global infectious diseases, responsible for 1-2 million deaths yearly. The rapid evolution and spread of drug resistance in parasites has led to an urgent need for the development of novel antimalarial targets. Proteases are a group of enzymes that play essential roles in parasite growth and invasion. The possibility of designing specific inhibitors for proteases makes them promising drug targets. Previously, combining a comparative genomics approach and a machine learning approach, we identified the complement of proteases (degradome in the malaria parasite Plasmodium falciparum and its sibling species 123, providing a catalog of targets for functional characterization and rational inhibitor design. Network analysis represents another route to revealing the role of proteins in the biology of parasites and we use this approach here to expand our understanding of the systems involving the proteases of P. falciparum. Results We investigated the roles of proteases in the parasite life cycle by constructing a network using protein-protein association data from the STRING database 4, and analyzing these data, in conjunction with the data from protein-protein interaction assays using the yeast 2-hybrid (Y2H system 5, blood stage microarray experiments 678, proteomics 9101112, literature text mining, and sequence homology analysis. Seventy-seven (77 out of 124 predicted proteases were associated with at least one other protein, constituting 2,431 protein-protein interactions (PPIs. These proteases appear to play diverse roles in metabolism, cell cycle regulation, invasion and infection. Their degrees of connectivity (i.e., connections to other proteins, range from one to 143. The largest protease-associated sub-network is the ubiquitin-proteasome system which is crucial for protein recycling and stress response. Proteases are also implicated in heat shock response, signal peptide

  5. Plasmodium falciparum Bloom homologue, a nucleocytoplasmic protein, translocates in 3' to 5' direction and is essential for parasite growth.

    Science.gov (United States)

    Rahman, Farhana; Tarique, Mohammed; Tuteja, Renu

    2016-05-01

    Malaria caused by Plasmodium, particularly Plasmodium falciparum, is the most serious and widespread parasitic disease of humans. RecQ helicase family members are essential in homologous recombination-based error-free DNA repair processes in all domains of life. RecQ helicases present in each organism differ and several homologues have been identified in various multicellular organisms. These proteins are involved in various pathways of DNA metabolism by providing duplex unwinding function. Five members of RecQ family are present in Homo sapiens but P. falciparum contains only two members of this family. Here we report the detailed biochemical and functional characterization of the Bloom (Blm) homologue (PfBlm) from P. falciparum 3D7 strain. Purified PfBlm exhibits ATPase and 3' to 5' direction specific DNA helicase activity. The calculated average reaction rate of ATPase was ~13 pmol of ATP hydrolyzed/min/pmol of enzyme. The immunofluorescence assay results show that PfBlm is expressed in all the stages of intraerythrocytic development of the P. falciparum 3D7 strain. In some stages of development in addition to nucleus PfBlm also localizes in the cytoplasm. The gene disruption studies of PfBlm by dsRNA showed that it is required for the ex-vivo intraerythrocytic development of the parasite P. falciparum 3D7 strain. The dsRNA mediated inhibition of parasite growth suggests that a variety of pathways are affected resulting in curtailing of the parasite growth. This study will be helpful in unravelling the basic mechanism of DNA transaction in the malaria parasite and additionally it may provide leads to understand the parasite specific characteristics of this protein.

  6. Plasmodium falciparum malaria in infants under 5 kg: retrospective surveillance of hospital records in five sub-saharan African countries.

    Science.gov (United States)

    Alao, Maroufou J; Gbadoé, Adama D; Meremikwu, Martin; Tshefu, Antoinette; Tiono, Alfred B; Cousin, Marc; Hamed, Kamal

    2013-04-01

    To investigate the disease burden, clinical features, treatment and outcomes of Plasmodium falciparum malaria in neonates and infants weighing Plasmodium falciparum malaria exists in this subpopulation. Further epidemiological data are needed to estimate malaria morbidity and mortality in young infants. Moreover, clinical evidence on the efficacy and safety of artemisinin-based combination therapies in this subpopulation is warranted.

  7. 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 seq...

  8. Invasion of erythrocytes in vitro by Plasmodium falciparum can be inhibited by monoclonal antibody directed against an S antigen.

    Science.gov (United States)

    Saul, A; Cooper, J; Ingram, L; Anders, R F; Brown, G V

    1985-11-01

    A monoclonal antibody has been produced which binds to the heat stable S antigen present in the FCQ-27/PNG isolate of Plasmodium falciparum. This monoclonal antibody also inhibits the invasion in vitro of erythrocytes by malarial merozoites thus demonstrating that the S antigens of Plasmodium falciparum may be a target of protective immune responses.

  9. Molecular epidemiology of Plasmodium vivax and Plasmodium falciparum malaria among Duffy-positive and Duffy-negative populations in Ethiopia.

    Science.gov (United States)

    Lo, Eugenia; Yewhalaw, Delenasaw; Zhong, Daibin; Zemene, Endalew; Degefa, Teshome; Tushune, Kora; Ha, Margaret; Lee, Ming-Chieh; James, Anthony A; Yan, Guiyun

    2015-02-19

    Malaria is the most prevalent communicable disease in Ethiopia, with 75% of the country's landmass classified as endemic for malaria. Accurate information on the distribution and clinical prevalence of Plasmodium vivax and Plasmodium falciparum malaria in endemic areas, as well as in Duffy-negative populations, is essential to develop integrated control strategies. A total of 390 and 416 community and clinical samples, respectively, representing different localities and age groups across Ethiopia were examined. Malaria prevalence was estimated using nested PCR of the 18S rRNA region. Parasite gene copy number was measured by quantitative real-time PCR and compared between symptomatic and asymptomatic samples, as well as between children/adolescents and adults from the local community. An approximately 500-bp segment of the human DARC gene was amplified and sequenced to identify Duffy genotype at the -33rd nucleotide position for all the clinical and community samples. Plasmodium vivax prevalence was higher in the south while P. falciparum was higher in the north. The prevalence of P. vivax and P. falciparum malaria is the highest in children compared to adolescents and adults. Four P. vivax infections were detected among the Duffy-negative samples. Samples from asymptomatic individuals show a significantly lower parasite gene copy number than those from symptomatic infections for P. vivax and P. falciparum. Geographical and age differences influence the distribution of P. vivax and P. falciparum malaria in Ethiopia. These findings offer evidence-based guidelines in targeting malaria control efforts in the country.

  10. In vitro inhibition of Plasmodium falciparum by substances isolated from Amazonian antimalarial plants

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    Valter F de Andrade-Neto

    2007-06-01

    Full Text Available In the present study, a quassinoid, neosergeolide, isolated from the roots and stems of Picrolemma sprucei (Simaroubaceae, the indole alkaloids ellipticine and aspidocarpine, isolated from the bark of Aspidosperma vargasii and A. desmanthum (Apocynaceae, respectively, and 4-nerolidylcatechol, isolated from the roots of Pothomorphe peltata (Piperaceae, all presented significant in vitro inhibition (more active than quinine and chloroquine of the multi-drug resistant K1 strain of Plasmodium falciparum. Neosergeolide presented activity in the nanomolar range. This is the first report on the antimalarial activity of these known, natural compounds. This is also the first report on the isolation of aspidocarpine from A. desmanthum. These compounds are good candidates for pre-clinical tests as novel lead structures with the aim of finding new antimalarial prototypes and lend support to the traditional use of the plants from which these compounds are derived.

  11. Discordance in drug resistance-associated mutation patterns in marker genes of Plasmodium falciparum and Plasmodium knowlesi during coinfections.

    Science.gov (United States)

    Tyagi, Rupesh K; Das, Manoj K; Singh, Shiv S; Sharma, Yagya D

    2013-05-01

    Human Plasmodium knowlesi infections have been reported from several South-East Asian countries, excluding India, but its drug susceptibility profile in mixed-infection cases remains unknown. The chloroquine resistance transporter (CRT) and dihydrofolate reductase (DHFR) genes of P. knowlesi and other Plasmodium species were sequenced from clinical isolates obtained from malaria patients living in the Andaman and Nicobar Islands, India. The merozoite surface protein-1 and 18S rRNA genes of P. knowlesi were also sequenced from these isolates. Among 445 samples analysed, only 53 of them had P. knowlesi-specific gene sequences. While 3 of the 53 cases (5.66%) had P. knowlesi monoinfection, the rest were coinfected with Plasmodium falciparum (86.79%, n = 46) or Plasmodium vivax (7.55%, n = 4), but none with Plasmodium malariae or Plasmodium ovale. There was discordance in the drug resistance-associated mutations among the coinfecting Plasmodium species. This is because the P. knowlesi isolates contained wild-type sequences, while P. falciparum isolates had mutations in the CRT and DHFR marker genes associated with a higher level of chloroquine and antifolate drug resistance, respectively. The mutation pattern indicates that the same patient, having a mixed infection, may be harbouring the drug-susceptible P. knowlesi parasite and a highly drug-resistant P. falciparum parasite. A larger human population in South-East Asia may be at risk of P. knowlesi infection than reported so far. The different drug susceptibility genotypes of P. knowlesi from its coinfecting Plasmodium species in mixed infections adds a new dimension to the malaria control programme, requiring formulation of an appropriate drug policy.

  12. Expression and biochemical characterization of Plasmodium falciparum DNA ligase I.

    Science.gov (United States)

    Buguliskis, Jeffrey S; Casta, Louis J; Butz, Charles E; Matsumoto, Yoshihiro; Taraschi, Theodore F

    2007-10-01

    We report that Plasmodium falciparum (Pf) encodes a 912 amino acid ATP-dependent DNA ligase. Protein sequence analysis of Pf DNA ligase I indicates a strong sequence similarity, particularly in the C-terminal region, to DNA ligase I homologues. The activity of recombinant Pf DNA ligase I (PfLigI) was investigated using protein expressed in HEK293 cells. The PfLigI gene product is approximately 94kDa and catalyzes phosphodiester bond formation on a singly nicked DNA substrate. The enzyme is most active at alkaline pH (8.5) and with Mg(2+) or Mn(2+) and ATP as cofactors. Kinetic studies of PfLigI revealed that the enzyme has similar substrate affinity (K(m) 2.6nM) as compared to human DNA ligase I and k(cat) (2.3x10(-3)s(-1)) and k(cat)/K(m) (8.8x10(5)M(-1)s(-1)) which are similar to other ATP-dependent DNA ligases. PfLigI was able to join RNA-DNA substrates only when the RNA sequence was upstream of the nick, confirming that it is DNA ligase I and has no associated DNA ligase III like activity.

  13. 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

    2014-01-01

    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.

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

    Science.gov (United States)

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

    2015-10-01

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

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

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

    Science.gov (United States)

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

    2014-09-01

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

  17. The SLC4A1 gene is under differential selective pressure in primates infected by Plasmodium falciparum and related parasites

    OpenAIRE

    Steiper, Michael E.; Walsh, Fiona; Zichello, Julia M.

    2012-01-01

    Malaria is a disease caused by Plasmodium parasites and is responsible for high mortality in humans. This disease is caused by four different species of Plasmodium though the main source of mortality is Plasmodium falciparum. Humans have a number of genetic adaptations that act to combat Plasmodium. One adaptation is a deletion in the SLC4A1 gene that leads to Southeast Asian ovalocytosis (SAO). There is evidence that SAO erythrocytes are resistant to multiple Plasmodium species. Here we anal...

  18. 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.

  19. Nonradioactive heteroduplex tracking assay for the detection of minority-variant chloroquine-resistant Plasmodium falciparum in Madagascar

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    Mwapasa Victor

    2009-03-01

    Full Text Available Abstract Background Strains of Plasmodium falciparum genetically resistant to chloroquine (CQ due to the presence of pfcrt 76T appear to have been recently introduced to the island of Madagascar. The prevalence of such resistant genotypes is reported to be low (P. falciparum isolates on the island. Previously, minority variant chloroquine resistant parasites were described in Malawian patients using an isotopic heteroduplex tracking assay (HTA, which can detect pfcrt 76T-bearing P. falciparum minority variants in individual patients that were undetectable by conventional PCR. However, as this assay required a radiolabeled probe, it could not be used in many resource-limited settings. Methods This study describes a digoxigenin (DIG-labeled chemiluminescent heteroduplex tracking assay (DIG-HTA to detect pfcrt 76T-bearing minority variant P. falciparum. This assay was compared to restriction fragment length polymorphism (RFLP analysis and to the isotopic HTA for detection of genetically CQ-resistant parasites in clinical samples. Results Thirty one clinical P. falciparum isolates (15 primary isolates and 16 recurrent isolates from 17 Malagasy children treated with CQ for uncomplicated malaria were genotyped for the pfcrt K76T mutation. Two (11.7% of 17 patients harboured genetically CQ-resistant P. falciparum strains after therapy as detected by HTA. RFLP analysis failed to detect any pfcrt K76T-bearing isolates. Conclusion These findings indicate that genetically CQ-resistant P. falciparum are more common than previously thought in Madagascar even though the fitness of the minority variant pfcrt 76T parasites remains unclear. In addition, HTAs for malaria drug resistance alleles are promising tools for the surveillance of anti-malarial resistance. The use of a non-radioactive label allows for the use of HTAs in malaria endemic countries.

  20. Effects ofPlasmodium falciparum-infected erythrocytes on matrix metalloproteinase-9 regulation in human microvascular endothelial cells

    Institute of Scientific and Technical Information of China (English)

    Sarah D Alessandro; Nicoletta Basilico; Mauro Prato

    2013-01-01

    Objective:To investigate the regulation of matrix metalloproteinases(MMPs) and tissue inhibitors of metalloproteinases(TIMPs) in human microvascular endothelium(HMEC-1) exposed to erythrocytes infected by different strains ofPlasmodium falciparum (P. falciparum).Methods:HMEC-1 cells were co-incubated for72 h with erythrocytes infected by late stage trophozoite of D10(chloroquine-sensitive) orW2(chloroquine-resistant)P. falciparum strains.Cell supernatants were then collected and the levels of pro- or active gelatinasesMMP-9 andMMP-2 were evaluated by gelatin zymography and densitometry.The release of pro-MMP-9,MMP-3,MMP-1 andTIMP-1 proteins was analyzed by western blotting and densitometry.Results:Infected erythrocytes inducedde novo proMMP-9 andMMP-9 release.Neither basal levels of proMMP-2 were altered, nor activeMMP-2 was found.MMP-3 andMMP-1 secretion was significantly enhanced, whereas basalTIMP-1 was unaffected.All effects were similar for both strains. Conclusions:P. falciparum parasites, either chloroquine-sensitive or -resistant, induce the release of activeMMP-9 protein from human microvascular endothelium, by impairing balances between proMMP-9 and its inhibitor, and by enhancing the levels of its activators.This work provides new evidence onMMP involvement in malaria, pointing atMMP-9 as a possible target in adjuvant therapy.

  1. Assessment of Plasmodium falciparum PfMDR1 transport rates using Fluo-4.

    Science.gov (United States)

    Friedrich, O; Reiling, S J; Wunderlich, J; Rohrbach, P

    2014-09-01

    Mutations in the multidrug resistance transporter of Plasmodium falciparum PfMDR1 have been implicated to play a significant role in the emergence of worldwide drug resistance, yet the molecular and biochemical mechanisms of this transporter are not well understood. Although it is generally accepted that drug resistance in P. falciparum is partly associated with PfMDR1 transport activity situated in the membrane of the digestive vacuole, direct estimates of the pump rate of this transport process in the natural environment of the intact host-parasite system have never been analysed. The fluorochrome Fluo-4 is a well-documented surrogate substrate of PfMDR1 and has been found to accumulate by actively being transported into the digestive vacuole of several parasitic strains. In the present study, we designed an approach to use Fluo-4 fluorescence uptake as a measure of compartmental Fluo-4 concentration accumulation in the different compartments of the host-parasite system. We performed a 'reverse Fluo-4 imaging' approach to relate fluorescence intensity to changes in dye concentration rather than Ca(2+) fluctuations and were able to calculate the overall rate of transport for PfMDR1 in Dd2 parasites. With this assay, we provide a powerful method to selectively measure the effect of PfMDR1 mutations on substrate transport kinetics. This will be of high significance for future compound screening to test for new drugs in resistant P. falciparum strains. © 2014 The Authors. Journal of Cellular and Molecular Medicine published by John Wiley & Sons Ltd and Foundation for Cellular and Molecular Medicine.

  2. Antimalarial efficacy of Albizia lebbeck (Leguminosae against Plasmodium falciparum in vitro & P. berghei in vivo

    Directory of Open Access Journals (Sweden)

    Shagun Kalia

    2015-01-01

    Full Text Available Background & objectives: Albizia lebbeck Benth. (Leguminosae has long been used in Indian traditional medicine. The current study was designed to test antimalarial activity of ethanolic bark extract of A. lebbeck (EBEAL. Methods: EBEAL was prepared by soxhlet extraction and subjected to phytochemical analysis. The extract was evaluated for its in vitro antimalarial activity against Plasmodium falciparum chloroquine (CQ sensitive (MRC2 and CQ resistant (RKL9 strains. Cytotoxicity (CC 50 of extract against HeLa cells was evaluated. Median lethal dose (LD 50 was determined to assess safety of EBEAL in BALB/c mice. Schizonticidal (100-1000 mg/kg and preventive (100-750 mg/kg activities of EBEAL were evaluated against P. berghei. Curative activity (100-750 mg/kg of extract was also evaluated. Results: Phytochemical screening revealed presence of alkaloids, flavonoids, phenols, saponins, terpenes and phytosterols. The extract exhibited IC 50 of 8.2 µg/ml (MRC2 and 5.1 µg/ml (RKL9. CC 50 of extract on HeLa cell line was calculated to be >1000 µg/ml. EBEAL showed selectivity indices (SI of >121.9 and >196.07 against MRC2 and RKL9 strains of P. falciparum, respectively. LD 50 of EBEAL was observed to be >5 g/kg. Dose-dependent chemosuppression was observed with significant ( p100 mg/kg. Significant (P<0.001 curative and repository activities were exhibited by 750 mg/kg concentration of extract on D7. Interpretation & conclusions: The present investigation reports antiplasmodial efficacy of EBEAL in vitro against P. falciparum as evident by high SI values. ED 50 of <100 mg/kg against P. berghei categorizes EBEAL as active antimalarial. Further studies need to be done to exploit its antiplasmodial activity further.

  3. Early Transcriptional Responses of HepG2-A 16 Liver Cells to Infection by Plasmodium falciparum Sporozoites

    Science.gov (United States)

    2011-07-29

    286, ’JC 30, pp Early Transcriptional Responses of HepG2-A 16 Liver Cells to Infection by Plasmodium falciparum Sporozoites*[i] Received for...7500 and󈧏Sun BioMedical Technologies Inc., Ridgecrest, California 93555 Invasion of hepatocytes by Plasmodium sporozoites depos- ited by Anopheles...expression profiling of human HepG2-A16liver cells infected with Plasmodium falciparum sporozoites to understand the host early cellular events and

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

    OpenAIRE

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

    2006-01-01

    Malaria is undoubtedly the world's most devastating parasitic disease, affecting 300 to 500 million people every year. Some cases of Plasmodium falciparum infection progress to the deadly forms of the disease responsible for 1 to 3 million deaths annually. P. falciparum-infected erythrocytes adhere to host receptors in the deep microvasculature of several organs. The cytoadhesion of infected erythrocytes to placental syncytiotrophoblast receptors leads to pregnancy-associated malaria (PAM). T...

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

    OpenAIRE

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

    2006-01-01

    Malaria is undoubtedly the world's most devastating parasitic disease, affecting 300 to 500 million people every year. Some cases of Plasmodium falciparum infection progress to the deadly forms of the disease responsible for 1 to 3 million deaths annually. P. falciparum-infected erythrocytes adhere to host receptors in the deep microvasculature of several organs. The cytoadhesion of infected erythrocytes to placental syncytiotrophoblast receptors leads to pregnancy-associated malaria (PAM). T...

  6. Site-Specific Editing of the Plasmodium falciparum Genome Using Engineered Zinc-Finger Nucleases

    OpenAIRE

    Straimer, Judith; Lee, Marcus CS; Lee, Andrew H.; Zeitler, Bryan; Williams, April E.; Pearl, Jocelynn R.; Zhang, Lei; Rebar, Edward J.; Gregory, Philip D.; Llinás, Manuel; Urnov, Fyodor D; David A Fidock

    2012-01-01

    Malaria afflicts over 200 million people worldwide and its most lethal etiologic agent, Plasmodium falciparum, is evolving to resist even the latest-generation therapeutics. Efficient tools for genome-directed investigations of P. falciparum pathogenesis, including drug resistance mechanisms, are clearly required. Here we report rapid and targeted genetic engineering of this parasite, using zinc-finger nucleases (ZFNs) that produce a double-strand break in a user-defined locus and trigger hom...

  7. 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......, is geographically and temporally conserved raises hopes for the feasibility of developing VSA-based vaccines specifically designed to accelerate naturally acquired immunity, thereby enhancing protection against severe and life-threatening P. falciparum malaria....

  8. Tracking Origins and Spread of Sulfadoxine-Resistant Plasmodium falciparum dhps Alleles in Thailand▿

    OpenAIRE

    Alam, Md Tauqeer; Vinayak, Sumiti; Congpuong, Kanungnit; Wongsrichanalai, Chansuda; Satimai, Wichai; Slutsker, Laurence; Escalante, Ananias A.; Barnwell, John W.; Udhayakumar, Venkatachalam

    2010-01-01

    The emergence and spread of drug-resistant Plasmodium falciparum have been a major impediment for the control of malaria worldwide. Earlier studies have shown that similar to chloroquine (CQ) resistance, high levels of pyrimethamine resistance in P. falciparum originated independently 4 to 5 times globally, including one origin at the Thailand-Cambodia border. In this study we describe the origins and spread of sulfadoxine-resistance-conferring dihydropteroate synthase (dhps) alleles in Thail...

  9. Case report of Plasmodium falciparum malaria presenting as wide complex tachycardia

    Institute of Scientific and Technical Information of China (English)

    Sunil Kumar; Diwan SK; Mahajan SN; Shilpa Bawankule; Chetan Mahure

    2011-01-01

    Malaria caused by Plasmodium falciparum is a multisystem disorder and may have diversity of clinical presentations. We are presenting a case report of patients of falciparum malaria who presented to us with palpitation and fever. On electrocardiogram he had wide complex tachycardia. This case reiterates the need to think of malaria in any case with symptoms of fever with chills, even with various unusual presentations like palpitation due to wide complex tachycardia, especially in endemic country like India.

  10. A Replicating Adenovirus Capsid Display Recombinant Elicits Antibodies against Plasmodium falciparum Sporozoites in Aotus nancymaae Monkeys

    OpenAIRE

    Karen, Kasey A.; Deal, Cailin; Adams, Robert J; Nielsen, Carolyn; Ward, Cameron; Espinosa, Diego A.; Xie, Jane; Zavala,Fidel; Ketner, Gary

    2014-01-01

    Decades of success with live adenovirus vaccines suggest that replication-competent recombinant adenoviruses (rAds) could serve as effective vectors for immunization against other pathogens. To explore the potential of a live rAd vaccine against malaria, we prepared a viable adenovirus 5 (Ad5) recombinant that displays a B-cell epitope from the circumsporozoite protein (CSP) of Plasmodium falciparum on the virion surface. The recombinant induced P. falciparum sporozoite-neutralizing antibodie...

  11. Implication of a Plasmodium falciparum gene in the switch between asexual reproduction and gametocytogenesis.

    Science.gov (United States)

    Gardiner, Donald L; Dixon, Matthew W A; Spielmann, Tobias; Skinner-Adams, Tina S; Hawthorne, Paula L; Ortega, Maria R; Kemp, David J; Trenholme, Katharine R

    2005-04-01

    Gametocytogenesis is fundamental for transmission of the malaria parasite Plasmodium falciparum from the human host to the mosquito vector, yet very little is understood about what triggers the switch between asexual reproduction and gametocytogenesis. Arresting the progression through the sexual cycle would block transmission of this disease. Here we identify a novel gene in P. falciparum that when genetically silenced reduces gametocyte production by a factor of 6, and when complemented up-regulates gametocyte-specific gene transcription.

  12. 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....

  13. Analysis of malaria parasite phenotypes using experimental genetic crosses of Plasmodium falciparum

    OpenAIRE

    Ranford-Cartwright, Lisa C; Mwangi, Jonathan M.

    2012-01-01

    We review the principles of linkage analysis of experimental genetic crosses and their application to Plasmodium falciparum. Three experimental genetic crosses have been performed using the human malaria parasite P. falciparum. Linkage analysis of the progeny of these crosses has been used to identify parasite genes important in phenotypes such as drug resistance, parasite growth and virulence, and transmission to mosquitoes. The construction and analysis of genetic maps has been used to char...

  14. Recombinant Plasmodium falciparum glutamate rich protein; purification and use in enzyme-linked immunosorbent assay

    DEFF Research Database (Denmark)

    Dziegiel, M; Borre, Mette; Jepsen, S

    1991-01-01

    A method for purification of a recombinant Plasmodium falciparum protein produced in E. coli and its use in an enzyme-linked immunosorbent assay (ELISA) is described. The cloned gene fragment encodes GLURP,489-1271 the carboxy-terminal 783 amino acid residue portion of a 1271 amino acid residue P...... of the immunogenicity of a possible future P. falciparum vaccine utilizing epitopes from GLURP....

  15. RELATIONSHIP OF HEPATIC AND RENAL DYSFUNCTION WITH HAEMORRHEOLOGICAL PARAMETERS IN PLASMODIUM FALCIPARUM MALARIA

    Directory of Open Access Journals (Sweden)

    Valluri Satya

    2015-04-01

    Full Text Available The clinical pattern of malaria has changed worldwide including India in last decade. Earlier cerebral malaria was the predominant manifestation of severe malaria, whereas now the combination of jaundice and renal failure are more common. Severe haemorrhage is seen in upto 5% of patients with severe malaria. Studies on renal and hepatic dys function in Plasmodium falciparum malaria are a plenty, but there is a paucity of studies correlating haemorrheological abnormalities with hepatic and renal dysfunction in Plasmodium falciparum malaria. METHODS : 100 patients of malaria with positive periph eral blood smear for plasmodium falciparum , out of which 50 cases with AKI and Hepatic failure during the period January 2012 - June 2013. I n department of general medicine, Government General Hospital, Kakinada. GROUP A : Comprising 50 consecutive adult pat ients of all age groups and both genders who had jaundice or renal failure or both at the time of admission. GROUP B: comprising 50 consecutive cases of plasmodium falciparum malaria and had no complications. RESULTS: In group A patients all parameters are significantly raised as compared to group B patients. CONCLUSION: 10% of patients had clinically overt bleeding manifestations, this indicates subclinical haemorrheological dysfunction in patients suffering from falciparum malaria with hepatic and renal d ysfunction, high incidence of subclinical DIC, evidenced by prolonged aPTT (56%, low total platelet count (58%, and PT (20%. An observational, screening, analytical prospective study. 100 cases of PF positive complicated and uncomplicated cases during t he period - January 2012 - June 2013

  16. Transgenic Anopheles stephensi coexpressing single-chain antibodies resist Plasmodium falciparum development.

    Science.gov (United States)

    Isaacs, Alison T; Jasinskiene, Nijole; Tretiakov, Mikhail; Thiery, Isabelle; Zettor, Agnès; Bourgouin, Catherine; James, Anthony A

    2012-07-10

    Anopheles stephensi mosquitoes expressing m1C3, m4B7, or m2A10 single-chain antibodies (scFvs) have significantly lower levels of infection compared to controls when challenged with Plasmodium falciparum, a human malaria pathogen. These scFvs are derived from antibodies specific to a parasite chitinase, the 25 kDa protein and the circumsporozoite protein, respectively. Transgenes comprising m2A10 in combination with either m1C3 or m4B7 were inserted into previously-characterized mosquito chromosomal "docking" sites using site-specific recombination. Transgene expression was evaluated at four different genomic locations and a docking site that permitted tissue- and sex-specific expression was researched further. Fitness studies of docking site and dual scFv transgene strains detected only one significant fitness cost: adult docking-site males displayed a late-onset reduction in survival. The m4B7/m2A10 mosquitoes challenged with P. falciparum had few or no sporozoites, the parasite stage infective to humans, in three of four experiments. No sporozoites were detected in m1C3/m2A10 mosquitoes in challenge experiments when both genes were induced at developmentally relevant times. These studies support the conclusion that expression of a single copy of a dual scFv transgene can completely inhibit parasite development without imposing a fitness cost on the mosquito.

  17. Selection and affinity maturation of IgNAR variable domains targeting Plasmodium falciparum AMA1.

    Science.gov (United States)

    Nuttall, Stewart D; Humberstone, Karen S; Krishnan, Usha V; Carmichael, Jennifer A; Doughty, Larissa; Hattarki, Meghan; Coley, Andrew M; Casey, Joanne L; Anders, Robin F; Foley, Michael; Irving, Robert A; Hudson, Peter J

    2004-04-01

    The new antigen receptor (IgNAR) is an antibody unique to sharks and consists of a disulphide-bonded dimer of two protein chains, each containing a single variable and five constant domains. The individual variable (V(NAR)) domains bind antigen independently, and are candidates for the smallest antibody-based immune recognition units. We have previously produced a library of V(NAR) domains with extensive variability in the CDR1 and CDR3 loops displayed on the surface of bacteriophage. Now, to test the efficacy of this library, and further explore the dynamics of V(NAR) antigen binding we have performed selection experiments against an infectious disease target, the malarial Apical Membrane Antigen-1 (AMA1) from Plasmodium falciparum. Two related V(NAR) clones were selected, characterized by long (16- and 18-residue) CDR3 loops. These recombinant V(NAR)s could be harvested at yields approaching 5mg/L of monomeric protein from the E. coli periplasm, and bound AMA1 with nanomolar affinities (K(D)= approximately 2 x 10(-7) M). One clone, designated 12Y-2, was affinity-matured by error prone PCR, resulting in several variants with mutations mapping to the CDR1 and CDR3 loops. The best of these variants showed approximately 10-fold enhanced affinity over 12Y-2 and was Plasmodium falciparum strain-specific. Importantly, we demonstrated that this monovalent V(NAR) co-localized with rabbit anti-AMA1 antisera on the surface of malarial parasites and thus may have utility in diagnostic applications.

  18. Genome wide adaptations of Plasmodium falciparum in response to lumefantrine selective drug pressure.

    Directory of Open Access Journals (Sweden)

    Leah Mwai

    Full Text Available The combination therapy of the Artemisinin-derivative Artemether (ART with Lumefantrine (LM (Coartem® is an important malaria treatment regimen in many endemic countries. Resistance to Artemisinin has already been reported, and it is feared that LM resistance (LMR could also evolve quickly. Therefore molecular markers which can be used to track Coartem® efficacy are urgently needed. Often, stable resistance arises from initial, unstable phenotypes that can be identified in vitro. Here we have used the Plasmodium falciparum multidrug resistant reference strain V1S to induce LMR in vitro by culturing the parasite under continuous drug pressure for 16 months. The initial IC(50 (inhibitory concentration that kills 50% of the parasite population was 24 nM. The resulting resistant strain V1S(LM, obtained after culture for an estimated 166 cycles under LM pressure, grew steadily in 378 nM of LM, corresponding to 15 times the IC(50 of the parental strain. However, after two weeks of culturing V1S(LM in drug-free medium, the IC(50 returned to that of the initial, parental strain V1S. This transient drug tolerance was associated with major changes in gene expression profiles: using the PFSANGER Affymetrix custom array, we identified 184 differentially expressed genes in V1S(LM. Among those are 18 known and putative transporters including the multidrug resistance gene 1 (pfmdr1, the multidrug resistance associated protein and the V-type H+ pumping pyrophosphatase 2 (pfvp2 as well as genes associated with fatty acid metabolism. In addition we detected a clear selective advantage provided by two genomic loci in parasites grown under LM drug pressure, suggesting that all, or some of those genes contribute to development of LM tolerance--they may prove useful as molecular markers to monitor P. falciparum LM susceptibility.

  19. Using a genome-scale metabolic network model to elucidate the mechanism of chloroquine action in Plasmodium falciparum

    Directory of Open Access Journals (Sweden)

    Shivendra G. Tewari

    2017-08-01

    Full Text Available Chloroquine, long the default first-line treatment against malaria, is now abandoned in large parts of the world because of widespread drug-resistance in Plasmodium falciparum. In spite of its importance as a cost-effective and efficient drug, a coherent understanding of the cellular mechanisms affected by chloroquine and how they influence the fitness and survival of the parasite remains elusive. Here, we used a systems biology approach to integrate genome-scale transcriptomics to map out the effects of chloroquine, identify targeted metabolic pathways, and translate these findings into mechanistic insights. Specifically, we first developed a method that integrates transcriptomic and metabolomic data, which we independently validated against a recently published set of such data for Krebs-cycle mutants of P. falciparum. We then used the method to calculate the effect of chloroquine treatment on the metabolic flux profiles of P. falciparum during the intraerythrocytic developmental cycle. The model predicted dose-dependent inhibition of DNA replication, in agreement with earlier experimental results for both drug-sensitive and drug-resistant P. falciparum strains. Our simulations also corroborated experimental findings that suggest differences in chloroquine sensitivity between ring- and schizont-stage P. falciparum. Our analysis also suggests that metabolic fluxes that govern reduced thioredoxin and phosphoenolpyruvate synthesis are significantly decreased and are pivotal to chloroquine-based inhibition of P. falciparum DNA replication. The consequences of impaired phosphoenolpyruvate synthesis and redox metabolism are reduced carbon fixation and increased oxidative stress, respectively, both of which eventually facilitate killing of the parasite. Our analysis suggests that a combination of chloroquine (or an analogue and another drug, which inhibits carbon fixation and/or increases oxidative stress, should increase the clearance of P. falciparum

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

    Science.gov (United States)

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

    2017-08-24

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

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

    Directory of Open Access Journals (Sweden)

    Samad Ibitokou

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

  2. 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.

  3. The use of activated protein C in severe Plasmodium falciparum malaria.

    Science.gov (United States)

    Rankin, L G; Austin, D L H

    2007-06-01

    A 56-year-old man presented to a peripheral hospital in New Zealand with severe Plasmodium falciparum malaria with cerebral involvement and subsequently developed multi-system organ failure. Activated protein C was used in an attempt to stop the cascade of events into multi-organ failure. Severe infection with P. falciparum is life-threatening and appears to activate a hypercoagulable state similar to that of severe sepsis. Activated protein C is currently used in the treatment of severe sepsis and may provide a new adjuvant therapy for severe P. falciparum malaria.

  4. Structure of the catalytic domain of Plasmodium falciparum ARF GTPase-activating protein (ARFGAP)

    Energy Technology Data Exchange (ETDEWEB)

    Cook, William J.; Senkovich, Olga; Chattopadhyay, Debasish (UAB)

    2012-03-26

    The crystal structure of the catalytic domain of the ADP ribosylation factor GTPase-activating protein (ARFGAP) from Plasmodium falciparum has been determined and refined to 2.4 {angstrom} resolution. Multiwavelength anomalous diffraction (MAD) data were collected utilizing the Zn{sup 2+} ion bound at the zinc-finger domain and were used to solve the structure. The overall structure of the domain is similar to those of mammalian ARFGAPs. However, several amino-acid residues in the area where GAP interacts with ARF1 differ in P. falciparum ARFGAP. Moreover, a number of residues that form the dimer interface in the crystal structure are unique in P. falciparum ARFGAP.

  5. Artesunate plus pyronaridine for treating uncomplicated Plasmodium falciparum malaria

    Science.gov (United States)

    Bukirwa, Hasifa; Unnikrishnan, B; Kramer, Christine V; Sinclair, David; Nair, Suma; Tharyan, Prathap

    2014-01-01

    Background The World Health Organization (WHO) recommends that people with uncomplicated Plasmodium falciparum malaria are treated using Artemisinin-based Combination Therapy (ACT). ACT combines three-days of a short-acting artemisinin derivative with a longer-acting antimalarial which has a different mode of action. Pyronaridine has been reported as an effective antimalarial over two decades of use in parts of Asia, and is currently being evaluated as a partner drug for artesunate. Objectives To evaluate the efficacy and safety of artesunate-pyronaridine compared to alternative ACTs for treating people 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; LILACS; ClinicalTrials.gov; the metaRegister of Controlled Trials (mRCT); and the WHO International Clinical Trials Search Portal up to 16 January 2014. We searched reference lists and conference abstracts, and contacted experts for information about ongoing and unpublished trials. Selection criteria Randomized controlled trials of artesunate-pyronaridine versus other ACTs in adults and children with uncomplicated P. falciparum malaria. For the safety analysis, we also included adverse events data from trials comparing any treatment regimen containing pyronaridine with regimens not containing pyronaridine. Data collection and analysis Two authors independently assessed trial eligibility and risk of bias, and extracted data. We combined dichotomous data using risk ratios (RR) and continuous data using mean differences (MD), and presented all results with a 95% confidence interval (CI). We used the GRADE approach to assess the quality of evidence. Main results We included six randomized controlled trials enrolling 3718 children and adults. Artesunate-pyronaridine versus artemether-lumefantrine In two multicentre trials, enrolling

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

    DEFF Research Database (Denmark)

    Oberli, Alexander; Zurbrügg, Laura; Rusch, Sebastian;

    2016-01-01

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

  7. 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.

  8. Identification of phosphorylated proteins in erythrocytes infected by the human malaria parasite Plasmodium falciparum

    Directory of Open Access Journals (Sweden)

    Xia Dong

    2009-05-01

    Full Text Available Abstract Background Previous comparative proteomic analysis on Plasmodium falciparum isolates of different adhesion properties suggested that protein phosphorylation varies between isolates with different cytoadherence properties. But the extent and dynamic changes in phosphorylation have not been systematically studied. As a baseline for these future studies, this paper examined changes in the phosphoproteome of parasitized red blood cells (pRBC. Methods Metabolic labelling with [35S] methionine on pRBC and 2D gel electrophoresis (2-DE has previously been used to show the expression of parasite proteins and changes in protein iso-electric point (PI. 2-DE of different parasite strains was combined with immunoblotting using monoclonal antibodies specifically to phosphorylated serine/threonine and tyrosine, to obtain the phosphorylation profiles throughout the erythrocytic lifecycle. Affinity chromatography was used to purify/enrich phosphorylated proteins and these proteins from mature trophozoite stages which were identified using high-accuracy mass spectrometry and MASCOT search. Results 2D-immunoblots showed that P. falciparum infection greatly increased phosphorylation of a set of proteins in pRBC, the dominant size classes for phosphorylated tyrosine proteins were 95, 60, 50 and 30 kDa and for phosphorylated serine/threonine were 120, 95, 60, 50, 43, 40 and 30 kDa. The most abundant molecules from 2D-gel mapping of phosphorylated proteins in ItG infected RBCs were identified by MALDI-TOF. A proteomic overview of phosphorylated proteins in pRBC was achieved by using complementary phosphorylated protein enrichment techniques combined with nano-flow LC/MS/MS analysis and MASCOT MS/MS ions search with phosphorylation as variable modifications. The definite phosphoproteins of pRBC are reported and discussed. Conclusion Protein phosphorylation is a major process in P. falciparum-parasitized erythrocytes. Preliminary screens identified 170 P

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

    Science.gov (United States)

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

    2013-05-01

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

  10. Predictors of Plasmodium falciparum malaria incidence in Chano Mille, South Ethiopia: a longitudinal study.

    Science.gov (United States)

    Loha, Eskindir; Lindtjørn, Bernt

    2012-09-01

    We assessed potential effects of local meteorological and environmental conditions, indoor residual spraying with insecticides, insecticide-treated nets (ITNs) use at individual and community levels, and individual factors on Plasmodium falciparum malaria incidence in a village in south Ethiopia. A cohort of 8,121 people was followed for 101 weeks with active and passive surveillance. Among 317 microscopically confirmed P. falciparum malaria episodes, 29.3% occurred among temporary residents. The incidence density was 3.6/10,000 person-weeks of observation. We observed higher malaria incidence among males, children 5-14 years of age, ITNs non-users, the poor, and people who lived closer to vector breeding places. Rainfall increased and indoor residual spraying with Deltamethrin reduced falciparum incidence. Although ITNs prevented falciparum malaria for the users, we did not find that free mass ITNs distribution reduced falciparum malaria on a village level.

  11. A malaria vaccine that elicits in humans antibodies able to kill Plasmodium falciparum.

    Directory of Open Access Journals (Sweden)

    2005-11-01

    Full Text Available BACKGROUND: Plasmodium falciparum merozoite surface protein 3 is a malaria vaccine candidate that was identified, characterised, and developed based on a unique immuno-clinical approach. The vaccine construct was derived from regions fully conserved among various strains and containing B cell epitopes targeted by human antibodies (from malaria-immune adults that are able to mediate a monocyte-dependent parasite killing effect. The corresponding long synthetic peptide was administered to 36 volunteers, with either alum or Montanide ISA720 as adjuvant. METHODS AND FINDINGS: Both formulations induced cellular and humoral immune responses. With alum, the responses lasted up to 12 mo. The vaccine-induced antibodies were predominantly of cytophilic classes, i.e., able to cooperate with effector cells. In vitro, the antibodies induced an inhibition of the P. falciparum erythrocytic growth in a monocyte-dependent manner, which was in most instances as high as or greater than that induced by natural antibodies from immune African adults. In vivo transfer of the volunteers' sera into P. falciparum-infected humanized SCID mice profoundly reduced or abrogated parasitaemia. These inhibitory effects were related to the antibody reactivity with the parasite native protein, which was seen in 60% of the volunteers, and remained in samples taken 12 mo postimmunisation. CONCLUSION: This is the first malaria vaccine clinical trial to clearly demonstrate antiparasitic activity by vaccine-induced antibodies by both in vitro and in vivo methods. The results, showing the induction of long-lasting antibodies directed to a fully conserved polypeptide, also challenge current concepts about malaria vaccines, such as unavoidable polymorphism, low antigenicity, and poor induction of immune memory.

  12. A malaria vaccine that elicits in humans antibodies able to kill Plasmodium falciparum.

    Directory of Open Access Journals (Sweden)

    Pierre Druilhe

    2005-11-01

    Full Text Available Plasmodium falciparum merozoite surface protein 3 is a malaria vaccine candidate that was identified, characterised, and developed based on a unique immuno-clinical approach. The vaccine construct was derived from regions fully conserved among various strains and containing B cell epitopes targeted by human antibodies (from malaria-immune adults that are able to mediate a monocyte-dependent parasite killing effect. The corresponding long synthetic peptide was administered to 36 volunteers, with either alum or Montanide ISA720 as adjuvant.Both formulations induced cellular and humoral immune responses. With alum, the responses lasted up to 12 mo. The vaccine-induced antibodies were predominantly of cytophilic classes, i.e., able to cooperate with effector cells. In vitro, the antibodies induced an inhibition of the P. falciparum erythrocytic growth in a monocyte-dependent manner, which was in most instances as high as or greater than that induced by natural antibodies from immune African adults. In vivo transfer of the volunteers' sera into P. falciparum-infected humanized SCID mice profoundly reduced or abrogated parasitaemia. These inhibitory effects were related to the antibody reactivity with the parasite native protein, which was seen in 60% of the volunteers, and remained in samples taken 12 mo postimmunisation.This is the first malaria vaccine clinical trial to clearly demonstrate antiparasitic activity by vaccine-induced antibodies by both in vitro and in vivo methods. The results, showing the induction of long-lasting antibodies directed to a fully conserved polypeptide, also challenge current concepts about malaria vaccines, such as unavoidable polymorphism, low antigenicity, and poor induction of immune memory.

  13. The effects of a partitioned var gene repertoire of Plasmodium falciparum on antigenic diversity and the acquisition of clinical immunity

    Directory of Open Access Journals (Sweden)

    Arinaminpathy Nimalan

    2008-01-01

    Full Text Available Abstract Background The human malaria parasite Plasmodium falciparum exploits antigenic diversity and within-host antigenic variation to evade the host's immune system. Of particular importance are the highly polymorphic var genes that encode the family of cell surface antigens PfEMP1 (Plasmodium falciparum Erythrocyte Membrane Protein 1. It has recently been shown that in spite of their extreme diversity, however, these genes fall into distinct groups according to chromosomal location or sequence similarity, and that recombination may be confined within these groups. Methods This study presents a mathematical analysis of how recombination hierarchies affect diversity, and, by using simple stochastic simulations, investigates how intra- and inter-genic diversity influence the rate at which individuals acquire clinical immunity. Results The analysis demonstrates that the partitioning of the var gene repertoire has a limiting effect on the total diversity attainable through recombination and that the limiting effect is strongly influenced by the respective sizes of each of the partitions. Furthermore, by associating expression of one of the groups with severe malaria it is demonstrated how a small number of infections can be sufficient to protect against disease despite a seemingly limitless number of possible non-identical repertoires. Conclusion Recombination hierarchies within the var gene repertoire of P. falciparum have a severe effect on strain diversity and the process of acquiring immunity against clinical malaria. Future studies will show how the existence of these recombining groups can offer an evolutionary advantage in spite of their restriction on diversity.

  14. Genotyping of chloroquine resistant Plasmodium falciparum in wild caught Anopheles minimus mosquitoes in a malaria endemic area of Assam, India.

    Science.gov (United States)

    Sarma, D K; Mohapatra, P K; Bhattacharyya, D R; Mahanta, J; Prakash, A

    2014-09-01

    We validated the feasibility of using Plasmodium falciparum, the human malaria parasite, DNA present in wild caught vector mosquitoes for the characterization of chloroquine resistance status. House frequenting mosquitoes belonging to Anopheles minimus complex were collected from human dwellings in a malaria endemic area of Assam, Northeast India and DNA was extracted from the head-thorax region of individual mosquitoes. Anopheles minimus complex mosquitoes were identified to species level and screened for the presence of Plasmodium sp. using molecular tools. Nested PCR-RFLP method was used for genotyping of P. falciparum based on K76T mutation in the chloroquine resistance transporter (pfcrt) gene. Three of the 27 wild caught An. minimus mosquitoes were harbouring P. falciparum sporozoites (positivity 11.1%) and all 3 were had 76T mutation in the pfcrt gene, indicating chloroquine resistance. The approach of characterizing antimalarial resistance of malaria parasite in vector mosquitoes can potentially be used as a surveillance tool for monitoring transmission of antimalarial drug resistant parasite strains in the community.

  15. Spatial and space-time distribution of Plasmodium vivax and Plasmodium falciparum malaria in China, 2005-2014.

    Science.gov (United States)

    Hundessa, Samuel H; Williams, Gail; Li, Shanshan; Guo, Jinpeng; Chen, Linping; Zhang, Wenyi; Guo, Yuming

    2016-12-19

    Despite the declining burden of malaria in China, the disease remains a significant public health problem with periodic outbreaks and spatial variation across the country. A better understanding of the spatial and temporal characteristics of malaria is essential for consolidating the disease control and elimination programme. This study aims to understand the spatial and spatiotemporal distribution of Plasmodium vivax and Plasmodium falciparum malaria in China during 2005-2009. Global Moran's I statistics was used to detect a spatial distribution of local P. falciparum and P. vivax malaria at the county level. Spatial and space-time scan statistics were applied to detect spatial and spatiotemporal clusters, respectively. Both P. vivax and P. falciparum malaria showed spatial autocorrelation. The most likely spatial cluster of P. vivax was detected in northern Anhui province between 2005 and 2009, and western Yunnan province between 2010 and 2014. For P. falciparum, the clusters included several counties of western Yunnan province from 2005 to 2011, Guangxi from 2012 to 2013, and Anhui in 2014. The most likely space-time clusters of P. vivax malaria and P. falciparum malaria were detected in northern Anhui province and western Yunnan province, respectively, during 2005-2009. The spatial and space-time cluster analysis identified high-risk areas and periods for both P. vivax and P. falciparum malaria. Both malaria types showed significant spatial and spatiotemporal variations. Contrary to P. vivax, the high-risk areas for P. falciparum malaria shifted from the west to the east of China. Further studies are required to examine the spatial changes in risk of malaria transmission and identify the underlying causes of elevated risk in the high-risk areas.

  16. Paludismo por Plasmodium falciparum adquirido en África subsahariana Plasmodium falciparum malaria acquired in Subsaharian Africa

    Directory of Open Access Journals (Sweden)

    Ricardo Durlach

    2009-02-01

    Full Text Available El objetivo de este trabajo es presentar los casos de paludismo por Plasmodium falciparum ocurridos en viajeros provenientes del África tropical, atendidos en el Hospital Alemán. Se definió paludismo de origen africano como la infección adquirida en un país del África subsahariana, diagnosticado y tratado en la Argentina. El diagnóstico se realizó por la clínica y la microscopía óptica en frotis de sangre periférica coloreados con Giemsa. Se revieron las historias clínicas de 11 pacientes adultos -cinco turistas y seis marineros mercantes- no oriundos de área endémica, sin condición inmunosupresora, ni morbilidad asociada, internados entre 1993 y 2007. El rango de edad fue de 21 a 48 años; nueve hombres y dos mujeres. Los pacientes fueron clasificados retrospectivamente en malaria grave (seis o no grave (cinco según cumplieran con uno o más de los criterios de gravedad de la Organización Mundial de la Salud. Todos presentaron fiebre como signo más significativo. Como complicaciones graves se observaron casos de insuficiencia renal, epistaxis, hemoglobinuria, hipoglucemia, edema pulmonar, acidosis y coma. Tres pacientes requirieron internación en la unidad de terapia intensiva. Todos sobrevivieron y solamente tres habían recibido la quimioprofilaxis correcta antes de viajar. El tratamiento se realizó con una o más de las siguientes drogas: mefloquina, quinidina, clindamicina y cotrimoxazol.The purpose of this paper is to present the cases of malaria caused by Plasmodium falciparum in travelers coming from tropical Africa, who were treated at the Hospital Alemán (Buenos Aires. African malaria was defined as an infection acquired in any country within Africa, diagnosed and treated in Argentina. Diagnostic tools included clinical features and optic microscopy with Giemsa stained peripheral blood films. We reviewed the medical records of 11 adult patients -five tourists and six sailors- with no history of malaria

  17. Continued Sensitivity of Plasmodium falciparum to Artemisinin in Guyana, With Absence of Kelch Propeller Domain Mutant Alleles

    Science.gov (United States)

    Rahman, Reyaud; Martin, Maria Jesus Sanchez; Persaud, Shamdeo; Ceron, Nicolas; Kellman, Dwayne; Musset, Lise; Carter, Keith H.; Ringwald, Pascal

    2016-01-01

    Because of concerns about possible emergence of artemisinin resistance strains of Plasmodium falciparum in mining areas of the interior of Guyana, a 7-day artesunate trial was conducted from March to December 2014. The day-3 parasite clearance rate, the efficacy of artesunate at day 28, and polymorphism of Kelch 13 (PfK13)—the marker of artemisinin resistance—were assessed. The study confirmed the continued sensitivity of P falciparum to artemisinin. A 7-day course of artesunate was 100% efficacious with only 2% (95% confidence interval, .1%–10.9%) of enrolled subjects positive at day 3. All day-0 parasite samples were wild type. Continued resistance monitoring is nevertheless recommended, given the widespread availability and uncontrolled use of artemisinin drugs in mining areas of Guyana.

  18. Pooled deep sequencing of Plasmodium falciparum isolates: an efficient and scalable tool to quantify prevailing malaria drug-resistance genotypes.

    Science.gov (United States)

    Taylor, Steve M; Parobek, Christian M; Aragam, Nash; Ngasala, Billy E; Mårtensson, Andreas; Meshnick, Steven R; Juliano, Jonathan J

    2013-12-15

    Molecular surveillance for drug-resistant malaria parasites requires reliable, timely, and scalable methods. These data may be efficiently produced by genotyping parasite populations using second-generation sequencing (SGS). We designed and validated a SGS protocol to quantify mutant allele frequencies in the Plasmodium falciparum genes dhfr and dhps in mixed isolates. We applied this new protocol to field isolates from children and compared it to standard genotyping using Sanger sequencing. The SGS protocol accurately quantified dhfr and dhps allele frequencies in a mixture of parasite strains. Using SGS of DNA that was extracted and then pooled from individual isolates, we estimated mutant allele frequencies that were closely correlated to those estimated by Sanger sequencing (correlations, >0.98). The SGS protocol obviated most molecular steps in conventional methods and is cost saving for parasite populations >50. This SGS genotyping method efficiently and reproducibly estimates parasite allele frequencies within populations of P. falciparum for molecular epidemiologic studies.

  19. Creation of cloned strains of chloroquine-resistant Plasmodium falciparum from Yunnan, China with resistance to dihydroartemisinin%云南省抗氯喹恶性疟原虫双氢青蒿素抗性株体外培育与单克隆品系的建立

    Institute of Scientific and Technical Information of China (English)

    杨亚明; 李雪平; 张苍林; 李奔福; 刘慧; 李丽

    2013-01-01

    目的 建立云南省恶性疟原虫抗双氢青蒿素的单克隆品系,为开展恶性疟原虫对青蒿素类的抗药性研究奠定基础. 方法 体外长期连续培养恶性疟原虫,采用体外间断双氢青蒿素药物刺激法对恶性疟原虫株进行抗药性培育,待达到一定抗药性后采用有限稀释法对虫株进行克隆,采用体外微量法测定克隆虫株对双氢青蒿素、青蒿素、氯喹的敏感性,并对其生物学特性进行鉴定. 结果 获得2个云南氯喹抗性恶性疟原虫对双氢青蒿素抗性的单克隆品系C10和H6,IC50值分别为39.01 nmol/L和26.91 nmol/L. 结论 经过8次体外间断药物刺激和筛选,获得2株恶性疟双氢青蒿素抗性单克隆品系,其药物耐受性水平与现场抗性株接近.%Objectives To establish monoclonal strains of Plasmodium falciparum from Yunnan Province with resistance to dihydroartemisinin and to lay the foundation for study of the resistance of P.falciparum to artemisinin-based drugs.Methods Strains of P.falciparum were cultured via long-term continuous in vitro culturing.Strains were intermittently challenged with dihydroartemisinin in vitro.After the strains developed a certain level of resistance to dihydroartemisinin according to a microtest assay,they were cloned using a limited dilution.Biological characteristics of sensitivity to dihydroartemisinin,artemisinin,and chloroquine in vitro were identified.Results Two monoclonal strains of dihydroartemisinin-resistant P.falciparum were obtained from chloroquine resistant P.falciparum originating in Yunnan.The IC50 of the C10 cloned strain was 39.01nmol/L and the IC50 of the H6 cloned strain was 26.91 nmol/L.Conclusion Two monoclonal strains of dihydroartemisinin-resistant P.falciparum were obtained after the parasites were intermittently challenged with 8 rounds of dihydroartemisinin in vitro.These strains had a level of drug resistance close to that of resistant strains from Yunnan.

  20. Crystallization and preliminary X-ray diffraction of malate dehydrogenase from Plasmodium falciparum

    NARCIS (Netherlands)

    Wrenger, Carsten; Mueller, Ingrid B.; Butzloff, Sabine; Jordanova, Rositsa; Lunev, Sergey; Groves, Matthew R.

    2012-01-01

    The expression, purification, crystallization and preliminary X-ray diffraction characterization of malate dehydrogenase (MDH) from the malarial parasite Plasmodium falciparum (PfMDH) are reported. In order to gain a deeper understanding of the function and role of PfMDH, the protein was purified to

  1. 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

  2. Inhibition of Plasmodium falciparum oocyst production by membrane-permeant cysteine protease inhibitor E64d.

    NARCIS (Netherlands)

    Eksi, S.; Czesny, B.; Gemert, G.J.A. van; Sauerwein, R.W.; Eling, W.M.C.; Williamson, K.C.

    2007-01-01

    During asexual intraerythrocytic growth, Plasmodium falciparum utilizes hemoglobin obtained from the host red blood cell (RBC) as a nutrient source. Papain-like cysteine proteases, falcipains 2 and 3, have been reported to be involved in hemoglobin digestion and are targets of current antimalarial d

  3. 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 His

  4. 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...

  5. 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...

  6. 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 H3K4...

  7. 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...

  8. 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...

  9. 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...

  10. 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...

  11. 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...

  12. High level of var2csa transcription by Plasmodium falciparum isolated from the placenta

    DEFF Research Database (Denmark)

    Tuikue Ndam, Nicaise G; Salanti, Ali; Bertin, Gwladys;

    2005-01-01

    Plasmodium falciparum parasites that bind to chondroitin sulphate A (CSA) express unique variant surface antigens that are involved in the placental sequestration that precipitates pregnancy-associated malaria (PAM). Two var gene subfamilies, var1csa and var2csa, have been associated with CSA bin...

  13. 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...

  14. 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...

  15. 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

  16. 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...

  17. Increased levels of soluble CD30 in plasma of patients with Plasmodium falciparum malaria

    DEFF Research Database (Denmark)

    Kemp, Kåre; Kurtzhals, Jørgen; Akanmori, Bartholomew D

    2002-01-01

    Levels of soluble CD30 (sCD30) in serum were elevated in patients with Plasmodium falciparum malaria but showed decline following treatment. The levels of sCD30 in serum were correlated significantly with the expression of gamma interferon by peripheral T cells. These data suggest that CD30...

  18. Independent origin of Plasmodium falciparum antifolate super-resistance, Uganda, Tanzania, and Ethiopia

    DEFF Research Database (Denmark)

    Alifrangis, Michael; Nag, Sidsel; Schousboe, Mette L

    2014-01-01

    Super-resistant Plasmodium falciparum threatens the effectiveness of sulfadoxine-pyrimethamine in intermittent preventive treatment for malaria during pregnancy. It is characterized by the A581G Pfdhps mutation on a background of the double-mutant Pfdhps and the triple-mutant Pfdhfr. Using sample...

  19. Soluble Plasmodium falciparum antigens contain carbohydrate moieties important for immune reactivity

    DEFF Research Database (Denmark)

    Jakobsen, P H; Theander, T G; Jensen, J B

    1987-01-01

    The importance of carbohydrate moieties for the antigenicity of purified soluble Plasmodium falciparum antigens from the asexual blood stage was tested. Digestion of the soluble antigens with alpha-D-galactosidase clearly affected the ability of the antigen to react with malaria-immune sera from ...

  20. Anaemia caused by asymptomatic Plasmodium falciparum infection in semi-immune African schoolchildren

    DEFF Research Database (Denmark)

    Kurtzhals, J A; Addae, M M; Akanmori, B D;

    1999-01-01

    A cohort of 250 Ghanaian schoolchildren aged 5-15 years was followed clinically and parasitologically for 4 months in 1997/98 in order to study the effect of asymptomatic Plasmodium falciparum infections on haematological indices and bone-marrow responses. Of the 250 children 65 met the predefine...

  1. Analysis of the plasmodium falciparum proteome by high-accuracy mass spectrometry

    DEFF Research Database (Denmark)

    Lasonder, Edwin; Ishihama, Yasushi; Andersen, Jens S;

    2002-01-01

    -accuracy (average deviation less than 0.02 Da at 1,000 Da) mass spectrometric proteome analysis of selected stages of the human malaria parasite Plasmodium falciparum. The analysis revealed 1,289 proteins of which 714 proteins were identified in asexual blood stages, 931 in gametocytes and 645 in gametes. The last...

  2. 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...

  3. 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 His

  4. 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

  5. Purification, crystallization and preliminary X-ray analysis of the aspartate aminotransferase of Plasmodium falciparum

    NARCIS (Netherlands)

    Jain, Rishabh; Jordanova, Rositsa; Mueller, Ingrid B.; Wrenger, Carsten; Groves, Matthew R.

    Aspartate aminotransferases (EC 2.6.1.1) catalyse the conversion of aspartate and alpha-ketoglutarate to oxaloacetate and glutamate in a reversible manner. Thus, the aspartate aminotransferase of Plasmodium falciparum (PfAspAT) plays a central role in the transamination of amino acids. Recent

  6. The multiplicity of Plasmodium falciparum infections is associated with acquired immunity to asexual blood stage antigens.

    NARCIS (Netherlands)

    Mayengue, P.I.; Luty, A.J.F.; Rogier, C.; Baragatti, M.; Kremsner, P.G.; Ntoumi, F.

    2009-01-01

    We evaluated the relationship between immune response markers and the multiplicity of Plasmodium falciparum infections in order to assess the validity of the latter as an indicator of the acquisition of anti-malarial immunity. Parasite populations present during malaria episodes of 64 Gabonese child

  7. 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...

  8. Neuronal monoamine reuptake inhibitors enhance in vitro susceptibility to chloroquine in resistant Plasmodium falciparum.

    OpenAIRE

    Coutaux, A F; Mooney, J. J.; Wirth, D. F.

    1994-01-01

    Chloroquine resistance in Plasmodium falciparum was reversed in vitro by the neuronal monoamine reuptake inhibitors and antidepressants desipramine, sertraline, fluoxetine, and norfluoxetine but not by carbamazepine, an antiseizure and mood-stabilizing tricyclic drug resembling desipramine which only weakly inhibits neuronal monoamine reuptake. These findings have important clinical implications for drug combination therapy.

  9. Drug resistance to sulphadoxine-pyrimethamine in Plasmodium falciparum malaria in Mlimba, Tanzania

    NARCIS (Netherlands)

    Mbugi, E.V.; Mutayoba, B.M.; Malisa, A.L.; Balthazary, S.T.; Nyambo, T.B.; Mshinda, H.

    2006-01-01

    Background - Sulphadoxine-pyrimethamine (SP) has been and is currently used for treatment of uncomplicated Plasmodium falciparum malaria in many African countries. Nevertheless, the response of parasites to SP treatment has shown significant variation between individuals. Methods - The genes for dih

  10. Mapping the genome of Plasmodium falciparum on the drug-like chemical space reveals novel anti-malarial targets and potential drug leads

    DEFF Research Database (Denmark)

    Jensen, Kasper; Plichta, Damian Rafal; Panagiotou, Gianni;

    2012-01-01

    The parasite Plasmodium falciparum is the main agent responsible for malaria. In this study, we exploited a recently published chemical library from GlaxoSmithKline (GSK) that had previously been confirmed to inhibit parasite growth of the wild type (3D7) and the multi-drug resistance (D2d) strains......, in order to uncover the weak links in the proteome of the parasite. We predicted 293 proteins of P. falciparum, including the six out of the seven verified targets for P. falciparum malaria treatment, as targets of 4645 GSK active compounds. Furthermore, we prioritized druggable targets, based on a number...... on integration of available chemical-protein and protein-protein interaction data. Our work suggests that a large number of the P. falciparum proteome is potentially druggable and could therefore serve as novel drug targets in the fight against malaria. At the same time, prioritized compounds from the GSK...

  11. 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

    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...... 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...

  12. Effect of meteorological variables on Plasmodium vivax and Plasmodium falciparum malaria in outbreak prone districts of Rajasthan, India.

    Science.gov (United States)

    Lingala, Mercy A L

    2017-03-09

    Malaria is a public health problem caused by Plasmodium parasite and transmitted by anopheline mosquitoes. Arid and semi-arid regions of western India are prone to malaria outbreaks. Malaria outbreak prone districts viz. Bikaner, Barmer and Jodhpur were selected to study the effect of meteorological variables on Plasmodium vivax and Plasmodium falciparum malaria outbreaks for the period of 2009-2012. The data of monthly malaria cases and meteorological variables was analysed using SPSS 20v. Spearman correlation analysis was conducted to examine the strength of the relationship between meteorological variables, P. vivax and P. falciparum malaria cases. Pearson's correlation analysis was carried out among the meteorological variables to observe the independent effect of each independent variable on the outcome. Results indicate that malaria outbreaks have occurred in Bikaner and Barmer due to continuous rains for more than two months. Rainfall has shown to be an important predictor of malaria outbreaks in Rajasthan. P. vivax is more significantly correlated with rainfall, minimum temperature (P<0.01) and less significantly with relative humidity (P<0.05); whereas P. falciparum is significantly correlated with rainfall, relative humidity (P<0.01) and less significantly with temperature (P<0.05). The determination of the lag period for P. vivax is relative humidity and for P. falciparum is temperature. The lag period between malaria cases and rainfall is shorter for P. vivax than P. falciparum. In conclusion, the knowledge generated is not only useful to take prompt malaria control interventions but also helpful to develop better forecasting model in outbreak prone regions. Copyright © 2017 The Author. Published by Elsevier Ltd.. All rights reserved.

  13. 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.

  14. Analysis of Antibodies Directed against Merozoite Surface Protein 1 of the Human Malaria Parasite Plasmodium falciparum

    Science.gov (United States)

    Woehlbier, Ute; Epp, Christian; Kauth, Christian W.; Lutz, Rolf; Long, Carole A.; Coulibaly, Boubacar; Kouyaté, Bocar; Arevalo-Herrera, Myriam; Herrera, Sócrates; Bujard, Hermann

    2006-01-01

    The 190-kDa merozoite surface protein 1 (MSP-1) of Plasmodium falciparum, an essential component in the parasite's life cycle, is a primary candidate for a malaria vaccine. Rabbit antibodies elicited by the heterologously produced MSP-1 processing products p83, p30, p38, and p42, derived from strain 3D7, were analyzed for the potential to inhibit in vitro erythrocyte invasion by the parasite and parasite growth. Our data show that (i) epitopes recognized by antibodies, which inhibit parasite replication, are distributed throughout the entire MSP-1 molecule; (ii) when combined, antibodies specific for different regions of MSP-1 inhibit in a strictly additive manner; (iii) anti-MSP-1 antibodies interfere with erythrocyte invasion as well as with the intraerythrocytic growth of the parasite; and (iv) antibodies raised against MSP-1 of strain 3D7 strongly cross-inhibit replication of the heterologous strain FCB-1. Accordingly, anti-MSP-1 antibodies appear to be capable of interfering with parasite multiplication at more than one level. Since the overall immunogenicity profile of MSP-1 in rabbits closely resembles that found in sera of Aotus monkeys immunized with parasite-derived MSP-1 and of humans semi-immune to malaria from whom highly inhibiting antigen-specific antibodies were recovered, we consider the findings reported here to be relevant for the development of MSP-1-based vaccines against malaria. PMID:16428781

  15. Acyclic Immucillin Phosphonates. Second-Generation Inhibitors of Plasmodium falciparum Hypoxanthine- Guanine-Xanthine Phosphoribosyltransferase

    Energy Technology Data Exchange (ETDEWEB)

    Hazelton, Keith Z. [Yeshiva Univ., New York, NY (United States); Ho, Meng-Chaio [Yeshiva Univ., New York, NY (United States); Cassera, Maria B. [Yeshiva Univ., New York, NY (United States); Clinch, Keith [Industrial Research Ltd., Lower Hutt (New Zealand); Crump, Douglas R. [Industrial Research Ltd., Lower Hutt (New Zealand); Rosario Jr., Irving [Yeshiva Univ., New York, NY (United States); Merino, Emilio F. [Yeshiva Univ., New York, NY (United States); Almo, Steve C. [Yeshiva Univ., New York, NY (United States); Tyler, Peter C. [Industrial Research Ltd., Lower Hutt (New Zealand); Schramm, Vern L. [Yeshiva Univ., New York, NY (United States)

    2012-06-22

    We found that Plasmodium falciparum is the primary cause of deaths from malaria. It is a purine auxotroph and relies on hypoxanthine salvage from the host purine pool. Purine starvation as an antimalarial target has been validated by inhibition of purine nucleoside phosphorylase. Hypoxanthine depletion kills Plasmodium falciparum in cell culture and in Aotus monkey infections. Hypoxanthine-guanine-xanthine phosphoribosyltransferase (HGXPRT) from P. falciparum is required for hypoxanthine salvage by forming inosine 5'-monophosphate, a branchpoint for all purine nucleotide synthesis in the parasite. We present a class of HGXPRT inhibitors, the acyclic immucillin phosphonates (AIPs), and cell permeable AIP prodrugs. The AIPs are simple, potent, selective, and biologically stable inhibitors. The AIP prodrugs block proliferation of cultured parasites by inhibiting the incorporation of hypoxanthine into the parasite nucleotide pool and validates HGXPRT as a target in malaria.

  16. 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...... been shown to recognise Plasmodium falciparum erythrocyte membrane protein 1 (PfEMP1). This protein is inserted by the parasite into the host cell membrane and mediates the adhesion to the venular endothelium of the host organism in vivo. METHODS: Erythrocytes infected at high parasitaemias...... with ethidium-bromide-labelled mature forms of P. falciparum parasites were sequentially exposed to immune plasma, goat anti-human immunoglobulin (Ig) G, and fluorescein-isothiocyanate-conjugated rabbit anti-goat Ig. Plasma antibodies recognising antigens exposed on the surface of parasitised erythrocytes were...

  17. Polyamine quinoline rhodium complexes: synthesis and pharmacological evaluation as antiparasitic agents against Plasmodium falciparum and Trichomonas vaginalis.

    Science.gov (United States)

    Stringer, Tameryn; Taylor, Dale; Guzgay, Hajira; Shokar, Ajit; Au, Aaron; Smith, Peter J; Hendricks, Denver T; Land, Kirkwood M; Egan, Timothy J; Smith, Gregory S

    2015-09-07

    A series of mono- and bis-salicylaldimine ligands and their corresponding Rh(i) complexes were prepared. The compounds were characterised using standard spectroscopic techniques including NMR, IR spectroscopy and mass spectrometry. The salicylaldimine ligands and complexes were screened for antiparasitic activity against two strains of Plasmodium falciparum i.e. the NF54 CQ-sensitive and K1 CQ-resistant strain as well as against the G3 isolate of Trichomonas vaginalis. The monomeric salicylaldimine quinolines exhibited good activity against the NF54 strain and the dimeric salicylaldimine quinolines exhibited no cross resistance across the two strains. The binuclear 5-chloro Rh(i) complex displayed the best activity against the Trichomonas vaginalis parasite, possibly a consequence of its enhanced lipophilicity. The compounds were also screened for cytotoxicity in vitro against WHCO1 oesophageal cancer cells. The monomeric salicylaldimine quinolines exhibited high selectivity towards malaria parasites compared to cancer cells, while the dimeric compounds were less selective.

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

    Science.gov (United States)

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

    2015-03-01

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

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

    Science.gov (United States)

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

    2014-01-01

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

  20. Functional Comparison of 45 Naturally Occurring Isoforms of the Plasmodium falciparum Chloroquine Resistance Transporter (PfCRT).

    Science.gov (United States)

    Callaghan, Paul S; Hassett, Matthew R; Roepe, Paul D

    2015-08-18

    At least 53 distinct isoforms of Plasmodium falciparum chloroquine resistance transporter (PfCRT) protein are expressed in strains or isolates of P. falciparum malarial parasites from around the globe. These parasites exhibit a range of sensitivities to chloroquine (CQ) and other drugs. Mutant PfCRT is believed to confer cytostatic CQ resistance (CQR(CS)) by transporting CQ away from its DV target (free heme released upon hemoglobin digestion). One theory is that variable CQ transport catalyzed by these different PfCRT isoforms is responsible for the range of CQ sensitivities now found for P. falciparum. Alternatively, additional mutations in drug-selected parasites, or additional functions of PfCRT, might complement PfCRT-mediated CQ transport in conferring the range of observed resistance phenotypes. To distinguish between these possibilities, we recently optimized a convenient method for measuring PfCRT-mediated CQ transport, involving heterologous expression in Saccharomyces cerevisiae. Here, we use this method to quantify drug transport activity for 45 of 53 of the naturally occurring PfCRT isoforms. Data show that variable levels of CQR likely depend upon either additional PfCRT functions or additional genetic events, including perhaps changes that influence DV membrane potential. The data also suggest that the common K76T PfCRT mutation that is often used to distinguish a P. falciparum CQR phenotype is not, in and of itself, a fully reliable indicator of CQR status.

  1. Polymorphism of the merozoite surface protein-1 block 2 region in Plasmodium falciparum isolates from Mauritania.

    Science.gov (United States)

    Ahmedou Salem, Mohamed Salem O; Ndiaye, Magatte; OuldAbdallahi, Mohamed; Lekweiry, Khadijetou M; Bogreau, Hervé; Konaté, Lassana; Faye, Babacar; Gaye, Oumar; Faye, Ousmane; Mohamed Salem O Boukhary, Ali O

    2014-01-23

    The genetic diversity of Plasmodium falciparum has been extensively studied in various parts of the world. However, limited data are available from Mauritania. The present study examined and compared the genetic diversity of P. falciparum isolates in Mauritania. Plasmodium falciparum isolates blood samples were collected from 113 patients attending health facilities in Nouakchott and Hodh El Gharbi regions. K1, Mad20 and RO33 allelic family of msp-1 gene were determined by nested PCR amplification. K1 family was the predominant allelic type carried alone or in association with Ro33 and Mad20 types (90%; 102/113). Out of the 113 P. falciparum samples, 93(82.3%) harboured more than one parasite genotype. The overall multiplicity of infection was 3.2 genotypes per infection. There was no significant correlation between multiplicity of infection and age of patients. A significant increase of multiplicity of infection was correlated with parasite densities. The polymorphism of P. falciparum populations from Mauritania was high. Infection with multiple P. falciparum clones was observed, as well as a high multiplicity of infection reflecting both the high endemicity level and malaria transmission in Mauritania.

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

    Science.gov (United States)

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

    2016-07-01

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

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

    Directory of Open Access Journals (Sweden)

    Salman Imtiaz

    2015-01-01

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

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

    Science.gov (United States)

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

    2015-03-18

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

  5. Evidence of a Mild Mutator Phenotype in Cambodian Plasmodium falciparum Malaria Parasites.

    Science.gov (United States)

    Lee, Andrew H; Fidock, David A

    2016-01-01

    Malaria control efforts have been continuously stymied by drug-resistant strains of Plasmodium falciparum, which typically originate in Southeast Asia prior to spreading into high-transmission settings in Africa. One earlier proposed explanation for Southeast Asia being a hotbed of resistance has been the hypermutability or "Accelerated Resistance to Multiple Drugs" (ARMD) phenotype, whereby multidrug-resistant Southeast Asian parasites were reported to exhibit 1,000-fold higher rates of resistance to unrelated antimalarial agents when compared to drug-sensitive parasites. However, three recent studies do not recapitulate this hypermutability phenotype. Intriguingly, genome sequencing of recently derived multidrug-resistant Cambodian isolates has identified a high proportion of DNA repair gene mutations in multidrug-resistant parasites, suggesting their potential role in shaping local parasite evolution. By adapting fluctuation assays for use in P. falciparum, we have examined the in vitro mutation rates of five recent Cambodian isolates and three reference laboratory strains. For these studies we also generated a knockout parasite line lacking the DNA repair factor Exonuclease I. In these assays, parasites were typed for their ability to acquire resistance to KAE609, currently in advanced clinical trials, yielding 13 novel mutations in the Na+/H+-ATPase PfATP4, the primary resistance determinant. We observed no evidence of hypermutability. Instead, we found evidence of a mild mutator (up to a 3.4-fold increase in mutation rate) phenotype in two artemisinin-resistant Cambodian isolates, which carry DNA repair gene mutations. We observed that one such mutation in the Mismatch Repair protein Mlh1 contributes to the mild mutator phenotype when modeled in yeast (scmlh1-P157S). Compared to basal rates of mutation, a mild mutator phenotype may provide a greater overall benefit for parasites in Southeast Asia in terms of generating drug resistance without incurring

  6. Changing trends in prevalence of different Plasmodium species with dominance of Plasmodium falciparum malaria infection in Aligarh (India).

    Science.gov (United States)

    Khan, Haris M; Shujatullah, Fatima; Ashfaq, Mohammad; Raza, Adil

    2011-01-01

    To determine the prevalence of malaria in Aligarh and analyze species dominance in different years over a decade. Diagnosis of malaria was done using microscopy as gold standard, rapid antigen detection assays and quantitative buffy coat (QBC) assays. Giemsa stained blood smear examination was done, thick and thin films were examined for presence of different Plasmodium spp. Rapid antigen detection assays employing detection of HRP-2 and parasite lactate dehydrogenase antigen (pLDH) by immunochromatography was done in patients whose blood smear found to be negative by conventional Giemsa slide examination. QBC was done in cases where there is strong clinical suspicion of malaria with blood smear negative, in patients with chronic malaria, splenomegaly, or in those patients who had inadequate treatment and for post-treatment follow up. Plasmodium vivax and Plasmodium falciparum were only species detected in our hospital. Overall prevalence of malaria in Aligarh was found to be 8.8%. The maximum prevalence of 20.1% was observed in year 2008 and lowest 2.3% in 2002. High prevalence of malaria is observed in this part of country with dominance of both species particularly Plasmodium falciparum should be monitored and factors accounting for occurrence should be studied to employ effective control measures. Copyright © 2011 Hainan Medical College. Published by Elsevier B.V. All rights reserved.

  7. Changing trends in prevalence of different Plasmodium species with dominance of Plasmodium falciparum malaria infection in Aligarh (India)

    Institute of Scientific and Technical Information of China (English)

    Haris M Khan; Fatima Shujatullah; Mohammad Ashfaq; Adil Raza

    2011-01-01

    Objective: To determine the prevalence of malaria in Aligarh and analyze species dominance in different years over a decade. Methods: Diagnosis of malaria was done using microscopy as gold standard, rapid antigen detection assays and quantitative buffy coat (QBC) assays. Giemsa stained blood smear examination was done, thick and thin films were examined for presence of different Plasmodium spp. Rapid antigen detection assays employing detection of HRP-2 and parasite lactate dehydrogenase antigen (pLDH) by immunochromatography was done in patients whose blood smear found to be negative by conventional Giemsa slide examination. QBC was done in cases where there is strong clinical suspicion of malaria with blood smear negative, in patients with chronic malaria, splenomegaly, or in those patients who had inadequate treatment and for post-treatment follow up. Results: Plasmodium vivax and Plasmodium falciparum were only species detected in our hospital. Overall prevalence of malaria in Aligarh was found to be 8.8%. The maximum prevalence of 20.1% was observed in year 2008 and lowest 2.3% in 2002.Conclusions:High prevalence of malaria is observed in this part of country with dominance of both species particularly Plasmodium falciparum should be monitored and factors accounting for occurrence should be studied to employ effective control measures.

  8. 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.

  9. Human IGF1 regulates midgut oxidative stress and epithelial homeostasis to balance lifespan and Plasmodium falciparum resistance in Anopheles stephensi

    National Research Council Canada - National Science Library

    Drexler, Anna L; Pietri, Jose E; Pakpour, Nazzy; Hauck, Eric; Wang, Bo; Glennon, Elizabeth K K; Georgis, Martha; Riehle, Michael A; Luckhart, Shirley

    2014-01-01

    ...) within a physiologically relevant range (0.013-0.13 µM) in human blood reduced development of the human parasite Plasmodium falciparum in the Indian malaria mosquito Anopheles stephensi. Low IGF1 (0.013 µM...

  10. Diversidad genética de Plasmodium falciparum y sus implicaciones en la epidemiología de la malaria

    National Research Council Canada - National Science Library

    Judy Natalia Jiménez; Carlos Enrique Muskus; Iván Darío Vélez

    2005-01-01

    La diversidad genética le confiere a Plasmodium falciparum la capacidad de evadir la respuesta inmune del hospedero y producir variantes resistentes a medicamentos y a vacunas, aspectos que juegan un papel importante...

  11. Early gametocytes of the malaria parasite Plasmodium falciparum specifically remodel the adhesive properties of infected erythrocyte surface

    DEFF Research Database (Denmark)

    Tibúrcio, Marta; Silvestrini, Francesco; Bertuccini, Lucia

    2013-01-01

    In Plasmodium falciparum infections the parasite transmission stages, the gametocytes, mature in 10 days sequestered in internal organs. Recent studies suggest that cell mechanical properties rather than adhesive interactions play a role in sequestration during gametocyte maturation. It remains i...

  12. Recrudescence of Plasmodium falciparum malaria contracted in Lombok, Indonesia after quinine/doxycycline and mefloquine: case report.

    Science.gov (United States)

    Tish, K N; Pillans, P I

    1997-07-11

    A patient is reported who contracted Plasmodium falciparum malaria in Lombok, Indonesia. The infection recrudesced after quinine/doxycycline and mefloquine. Treatment with halofantrine was successful after he developed cerebral malaria with recovery.

  13. [Stain hybridization method with pRepHind probe for the diagnosis of Plasmodium falciparum].

    Science.gov (United States)

    Moleón Borodowsky, I

    1992-01-01

    A study was conducted on the parasitemia detection level and the specificity of the pRepHind DNA probe for diagnosing Plasmodium falciparum by the stain hybridization method. The parasitemia detection level was studied by using dilutions of a P. falciparum in vitro culture, adjusted by direct microscopic examination to 1; 0.1; 0.01; 0.001; 0.0001 and 0.00001% of parasited red cells. Specificity was increased by using DNA extractions from P. Yoelii, P. berghei and human leucocytes. The results showed that the method was able to detect 0.0001% of parasitemia starting from DNA extractions of 100 L infected red cells. The pRepHind probe only detected specifically DNA from P. falciparum. It is concluded that the method is suitable for being used in the diagnosis of infection due to P. falciparum.

  14. 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.

  15. Functional characterization of a SUMO deconjugating protease of Plasmodium falciparum using newly identified small molecule inhibitors.

    Science.gov (United States)

    Ponder, Elizabeth L; Albrow, Victoria E; Leader, Brittany A; Békés, Miklós; Mikolajczyk, Jowita; Fonović, Urša Pečar; Shen, Aimee; Drag, Marcin; Xiao, Junpeng; Deu, Edgar; Campbell, Amy J; Powers, James C; Salvesen, Guy S; Bogyo, Matthew

    2011-06-24

    Small ubiquitin-related modifier (SUMO) is implicated in the regulation of numerous biological processes including transcription, protein localization, and cell cycle control. Protein modification by SUMO is found in Plasmodium falciparum; however, its role in the regulation of the parasite life cycle is poorly understood. Here we describe functional studies of a SUMO-specific protease (SENP) of P. falciparum, PfSENP1 (PFL1635w). Expression of the catalytic domain of PfSENP1 and biochemical profiling using a positional scanning substrate library demonstrated that this protease has unique cleavage sequence preference relative to the human SENPs. In addition, we describe a class of small molecule inhibitors of this protease. The most potent lead compound inhibited both recombinant PfSENP1 activity and P. falciparum replication in infected human blood. These studies provide valuable new tools for the study of SUMOylation in P. falciparum. Copyright © 2011 Elsevier Ltd. All rights reserved.

  16. Short report: polymorphisms in the chloroquine resistance transporter gene in Plasmodium falciparum isolates from Lombok, Indonesia.

    Science.gov (United States)

    Huaman, Maria Cecilia; Yoshinaga, Kazumi; Suryanatha, Aan; Suarsana, Nyoman; Kanbara, Hiroji

    2004-07-01

    The polymorphisms in the Plasmodium falciparum multidrug resistance 1 (pfmdr1) and P. falciparum chloroquine resistance transporter (pfcrt) genes, which are associated with chloroquine resistance, were examined in 48 P. falciparum isolates from uncomplicated malaria patients from the West Lombok District in Indonesia. The point mutation N86Y in pfmdr1 was present in 35.4% of the isolates and mutation K76T in pfcrt was found in all but one of the samples studied. Identified pfcrt haplotypes were mainly identical to the Papua New Guinea type S(agt)VMNT (42 of 48, 87.5%), and a few isolates had the Southeast Asia type CVIET (5 of 48, 10.4%). Moreover, one P. falciparum isolate harbored the K76N mutation, giving rise to the haplotype CVMNN, which was not previously reported in field isolates. Our findings suggest that chloroquine resistance in this area might have the same origin as in Papua New Guinea.

  17. Signaling transcript profile of the asexual intraerythrocytic development cycle of Plasmodium falciparum induced by melatonin and cAMP

    Science.gov (United States)

    Rozanski, Andrei; Parreira, Kleber S.; Moraes, Miriam S.; Martins, David C.; Hashimoto, Ronaldo F.; Galante, Pedro A.F.; Garcia, Célia R.S.

    2016-01-01

    According to the World Health Organization (WHO), Plasmodium falciparum is the deadliest parasite among all species. This parasite possesses the ability to sense molecules, including melatonin (MEL) and cAMP, and modulate its cell cycle accordingly. MEL synchronizes the development of this malaria parasite by activating several cascades, including the generation of the second messenger cAMP. Therefore, we performed RNA sequencing (RNA-Seq) analysis in P. falciparum erythrocytic stages (ring, trophozoite and schizont) treated with MEL and cAMP. To investigate the expression profile of P. falciparum genes regulated by MEL and cAMP, we performed RNA-Seq analysis in three P. falciparum strains (control, 3D7; protein kinase 7 knockout, PfPK7-; and PfPK7 complement, PfPK7C). In the 3D7 strain, 38 genes were differentially expressed upon MEL treatment; however, none of the genes in the trophozoite (T) stage PfPK7- knockout parasites were differentially expressed upon MEL treatment for 5 hours compared to untreated controls, suggesting that PfPK7 may be involved in the signaling leading to differential gene expression. Moreover, we found that MEL modified the mRNA expression of genes encoding membrane proteins, zinc ion-binding proteins and nucleic acid-binding proteins, which might influence numerous functions in the parasite. The RNA-Seq data following treatment with cAMP show that this molecule modulates different genes throughout the intraerythrocytic cycle, namely, 75, 101 and 141 genes, respectively, in the ring (R), T and schizont (S) stages. Our results highlight P. falciparum's perception of the external milieu through the signaling molecules MEL and cAMP, which are able to drive to changes in gene expression in the parasite. PMID:28050233

  18. The Severity of Plasmodium falciparum infection is associated with transcript levels of var genes encoding endothelial protein C receptor-binding P. falciparum erythrocyte membrane protein 1

    DEFF Research Database (Denmark)

    Mkumbaye, Sixbert I; Wang, Christian W; Lyimo, Eric

    2017-01-01

    By attaching infected erythrocytes to the vascular lining, Plasmodium falciparum parasites leave blood circulation and avoid splenic clearance. This sequestration is central to pathogenesis. Severe malaria is associated with parasites expressing an antigenically distinct P. falciparum erythrocyte...

  19. 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

  20. 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.

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

    DEFF Research Database (Denmark)

    Helleberg, Marie; Goka, Bamenla Q; Akanmori, Bartholomew D

    2005-01-01

    BACKGROUND: Severe anaemia can develop in the aftermath of Plasmodium falciparum malaria because of protracted bone marrow suppression, possibly due to residual subpatent parasites. MATERIALS AND METHODS: Blood was collected from patients with recent malaria and negative malaria microscopy....... Detection of the Plasmodium antigens, lactate dehydrogenase (Optimal), aldolase and histidine rich protein 2 (Now malaria) were used to differentiate between patients with (1) no malaria, (2) recent cleared malaria, (3) persistent P. falciparum infection. Red cell distribution width (RDW), plasma levels...

  2. Identification and Localization of Minimal MHC-restricted CD8+ T Cell Epitopes within the Plasmodium falciparum AMA1 Protein

    Science.gov (United States)

    2010-08-24

    Attribution License (http://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the...A, Muratova O, Awkal M, et al: Phase 1 clinical trial of apical membrane antigen 1: an asexual blood-stage vaccine for Plasmodium falciparum malaria...PfCP-2.9, an asexual blood-stage vaccine candidate of Plasmodium falciparum. Malar J 2010, 9(1):94. 40. Senger T, Becker MR, Schadlich L, Waterboer T

  3. 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 characterize...... comprehensive map of histone modifications in Plasmodium falciparum and highlight the utility of tandem MS for detailed analysis of peptides containing multiple PTMs....

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

    DEFF Research Database (Denmark)

    Oberli, Alexander; Zurbrügg, Laura; Rusch, Sebastian

    2016-01-01

    Adherence of Plasmodium falciparum-infected erythrocytes to host endothelium is conferred through the parasite-derived virulence factor P. falciparum erythrocyte membrane protein 1 (PfEMP1), the major contributor to malaria severity. PfEMP1 located at knob structures on the erythrocyte surface is...

  5. A pathway for phosphatidylcholine biosynthesis in Plasmodium falciparum involving phosphoethanolamine methylation.

    Science.gov (United States)

    Pessi, Gabriella; Kociubinski, Guillermo; Mamoun, Choukri Ben

    2004-04-20

    Plasmodium falciparum is the causative agent of the most severe form of human malaria. The rapid multiplication of the parasite within human erythrocytes requires an active production of new membranes. Phosphatidylcholine is the most abundant phospholipid in Plasmodium membranes, and the pathways leading to its synthesis are attractive targets for chemotherapy. In addition to its synthesis from choline, phosphatidylcholine is synthesized from serine via an unknown pathway. Serine, which is actively transported by Plasmodium from human serum and readily available in the parasite, is subsequently converted into phosphoethanolamine. Here, we describe in P. falciparum a plant-like S-adenosyl-l-methionine-dependent three-step methylation reaction that converts phosphoethanolamine into phosphocholine, a precursor for the synthesis of phosphatidylcholine. We have identified the gene, PfPMT, encoding this activity and shown that its product is an unusual phosphoethanolamine methyltransferase with no human homologs. P. falciparum phosphoethanolamine methyltransferase (Pfpmt) is a monopartite enzyme with a single catalytic domain that is responsible for the three-step methylation reaction. Interestingly, Pfpmt activity is inhibited by its product phosphocholine and by the phosphocholine analog, miltefosine. We show that miltefosine can also inhibit parasite proliferation within human erythrocytes. The importance of this enzyme in P. falciparum membrane biogenesis makes it a potential target for malaria chemotherapy.

  6. Glycophorin B is the erythrocyte receptor of Plasmodium falciparum erythrocyte-binding ligand, EBL-1.

    Science.gov (United States)

    Mayer, D C Ghislaine; Cofie, Joann; Jiang, Lubin; Hartl, Daniel L; Tracy, Erin; Kabat, Juraj; Mendoza, Laurence H; Miller, Louis H

    2009-03-31

    In the war against Plasmodium, humans have evolved to eliminate or modify proteins on the erythrocyte surface that serve as receptors for parasite invasion, such as the Duffy blood group, a receptor for Plasmodium vivax, and the Gerbich-negative modification of glycophorin C for Plasmodium falciparum. In turn, the parasite counters with expansion and diversification of ligand families. The high degree of polymorphism in glycophorin B found in malaria-endemic regions suggests that it also may be a receptor for Plasmodium, but, to date, none has been identified. We provide evidence from erythrocyte-binding that glycophorin B is a receptor for the P. falciparum protein EBL-1, a member of the Duffy-binding-like erythrocyte-binding protein (DBL-EBP) receptor family. The erythrocyte-binding domain, region 2 of EBL-1, expressed on CHO-K1 cells, bound glycophorin B(+) but not glycophorin B-null erythrocytes. In addition, glycophorin B(+) but not glycophorin B-null erythrocytes adsorbed native EBL-1 from the P. falciparum culture supernatants. Interestingly, the Efe pygmies of the Ituri forest in the Democratic Republic of the Congo have the highest gene frequency of glycophorin B-null in the world, raising the possibility that the DBL-EBP family may have expanded in response to the high frequency of glycophorin B-null in the population.

  7. Liver changes in severe Plasmodium falciparum malaria: histopathology, apoptosis and nuclear factor kappa B expression

    Science.gov (United States)

    2014-01-01

    Background Liver involvement in severe Plasmodium falciparum infection is commonly a significant cause of morbidity and mortality among humans. The clinical presentation of jaundice often reflects a certain degree of liver damage. This study investigated the liver pathology of severe P. falciparum malaria as well as the regulation and occurrence of apoptosis in cellular components of formalin-fixed, paraffin-embedded liver tissues. Methods The liver tissues used in the study came from patients who died from P. falciparum malaria with hyperbilirubinaemia (total bilirubin (TB) ≥ 51.3 μmol/L or 3 mg/dl) (12 cases), P. falciparum malaria without hyperbilirubinaemia (TB falciparum malaria were associated with higher TB level. Significant correlations were found between NF-κB p65 expression and apoptosis in Kupffer cells and lymphocytes in the portal tracts. Conclusions Hyperplastic Kupffer cells and portal tract inflammation are two main features found in the liver tissues of severe P. falciparum malaria cases. In addition, NF-κB is associated with Kupffer cells and lymphocyte apoptosis in severe P. falciparum malaria. PMID:24636003

  8. Bioinformatics analysis for structure and function ofCPR ofPlasmodium falciparum

    Institute of Scientific and Technical Information of China (English)

    ZhigangFan; Lingmin Zhang; GuogangYan; QiangWu; XiufengGan; Saifeng Zhong; GuifenLin

    2011-01-01

    Objective:To analyse the structure and function ofNADPH-cytochrome p450 reductase(CYPOR orCPR) fromPlasmodium falciparum (Pf), and to predict its’ drug target and vaccine target. Methods: The structure, function, drug target and vaccine target ofCPR fromPlasmodium falciparum were analyzed and predicted by bioinformatics methods.Results:PfCPR, which was olderCPR, had close relationship with theCPR from otherPlasmodium species, but it was distant from its hosts, such asHomo sapiens andAnopheles.PfCPR was located in the cellular nucleus ofPlasmodium falciparum.335aa-352aa and591aa -608aa were inserted the interior side of the nuclear membrane, while151aa-265aa was located in the nucleolus organizer regions.PfCPR had40 function sites and44 protein-protein binding sites in amino acid sequence. The teriary structure of 1aa-700aa was forcep-shaped with wings.15 segments ofPfCPR had no homology withHomo sapien CPR and most were exposed on the surface of the protein. These segments had25 protein-protein binding sites. While13other segments all possessed function sites. Conclusions: The evolution or genesis ofPlasmodium falciparum is earlier than those ofHomo sapiens. PfCPR is a possible resistance site of antimalarial drug and may involve immune evasion, which is associated with parasite of sporozoite in hepatocytes.PfCPR is unsuitable as vaccine target, but it has at least 13 ideal drug targets.

  9. REVERSAL OF HALOFANTRINE RESISTANCE IN PLASMODIUM FALCIPARUM BY PENFLURIDOL IN VITRO

    Directory of Open Access Journals (Sweden)

    M. Nateghpour

    1998-10-01

    Full Text Available Penfluridol, a neuroleptic drug, considerably reversed halofantrine resistance in T9.96HF halofantrine resistant strain of Plasmodium falicparum (originally chloroquine sensitive parasites, but not in K1HF halofantrine resistant strain (originally chloroquine resistant parasites

  10. Comparison of the antibody responses to Plasmodium vivax and Plasmodium falciparum antigens in residents of Mandalay, Myanmar

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    Kim Yeon-Joo

    2011-08-01

    Full Text Available Abstract Background The aim of this study was to investigate the profile of antibodies against several antigens of Plasmodium vivax and Plasmodium falciparum in Mandalay, Myanmar. Methods Malaria parasites were identified by microscopic examination. To test the antibodies against P. vivax and P. falciparum in sera, an indirect immunofluorescence antibody test (IFAT was performed using asexual blood parasite antigens. An enzyme-linked immunosorbent assay (ELISA was performed with circumsporozoite protein (CSP, Pvs25 and Pvs28 recombinant proteins of transmission-blocking vaccine candidates for P. vivax, and liver stage specific antigen-1 and -3 (PfLSA-1, PfLSA-3 for P. falciparum. Results Fourteen patients among 112 were found to be infected with P. vivax and 26 with P. falciparum by thick smear examination. Twenty-three patients were found to be infected with P. vivax, 19 with P. falciparum and five with both by thin smear examination. Blood samples were divided into two groups: Group I consisted of patients who were positive for infection by microscopic examination, and Group II consisted of those who showed symptoms, but were negative in microscopic examination. In P. falciparum, IgG against the blood stage antigen in Group I (80.8% was higher than in Group II (70.0%. In P. vivax, IgG against the blood stage antigen in Group I (53.8% was higher than in Group II (41.7%. However, the positivity rate of the PvCSP VK210 subtype in Group II (40.0% was higher than in Group I (23.1%. Similarly for the PvCSP VK247 subtype, Group II (21.7% was higher than that for Group I (9.6%. A similar pattern was observed in the ELISA using Pvs25 and Pvs28: positive rates of Group II were higher than those for Group I. However, those differences were not shown significant in statistics. Conclusions The positive rates for blood stage antigens of P. falciparum were higher in Group I than in Group II, but the positive rates for antigens of other stages (PfLSA-1 and -3

  11. Comparison of the antibody responses to Plasmodium vivax and Plasmodium falciparum antigens in residents of Mandalay, Myanmar.

    Science.gov (United States)

    Kim, Tong-Soo; Kim, Hyung-Hwan; Kim, Jung-Yeon; Kong, Yoon; Na, Byoung-Kuk; Lin, Khin; Moon, Sung-Ung; Kim, Yeon-Joo; Kwon, Myoung-Hee; Sohn, Youngjoo; Kim, Hyuck; Lee, Hyeong-Woo

    2011-08-06

    The aim of this study was to investigate the profile of antibodies against several antigens of Plasmodium vivax and Plasmodium falciparum in Mandalay, Myanmar. Malaria parasites were identified by microscopic examination. To test the antibodies against P. vivax and P. falciparum in sera, an indirect immunofluorescence antibody test (IFAT) was performed using asexual blood parasite antigens. An enzyme-linked immunosorbent assay (ELISA) was performed with circumsporozoite protein (CSP), Pvs25 and Pvs28 recombinant proteins of transmission-blocking vaccine candidates for P. vivax, and liver stage specific antigen-1 and -3 (PfLSA-1, PfLSA-3) for P. falciparum. Fourteen patients among 112 were found to be infected with P. vivax and 26 with P. falciparum by thick smear examination. Twenty-three patients were found to be infected with P. vivax, 19 with P. falciparum and five with both by thin smear examination. Blood samples were divided into two groups: Group I consisted of patients who were positive for infection by microscopic examination, and Group II consisted of those who showed symptoms, but were negative in microscopic examination. In P. falciparum, IgG against the blood stage antigen in Group I (80.8%) was higher than in Group II (70.0%). In P. vivax, IgG against the blood stage antigen in Group I (53.8%) was higher than in Group II (41.7%). However, the positivity rate of the PvCSP VK210 subtype in Group II (40.0%) was higher than in Group I (23.1%). Similarly for the PvCSP VK247 subtype, Group II (21.7%) was higher than that for Group I (9.6%). A similar pattern was observed in the ELISA using Pvs25 and Pvs28: positive rates of Group II were higher than those for Group I. However, those differences were not shown significant in statistics. The positive rates for blood stage antigens of P. falciparum were higher in Group I than in Group II, but the positive rates for antigens of other stages (PfLSA-1 and -3) showed opposite results. Similar to P. falciparum, the

  12. Multiple origins of Plasmodium falciparum dihydropteroate synthetase mutant alleles associated with sulfadoxine resistance in India.

    Science.gov (United States)

    Lumb, Vanshika; Das, Manoj K; Singh, Neeru; Dev, Vas; Khan, Wajihullah; Sharma, Yagya D

    2011-06-01

    With the spread of chloroquine (CQ)-resistant malaria in India, sulfadoxine-pyrimethamine (SP) alone or in combination with artesunate is used as an alternative antimalarial drug. Due to continuous drug pressure, the Plasmodium falciparum parasite is exhibiting resistance to antifolates because of mutations in candidate genes dihydrofolate reductase (dhfr) and dihydropteroate synthetase (dhps). Our earlier study on flanking microsatellite markers of dhfr mutant alleles from India had shown a single origin of the pyrimethamine resistance and some minor haplotypes which shared haplotypes with Southeast Asian (Thailand) strains. In the present study, we have analyzed 193 of these Indian P. falciparum isolates for 15 microsatellite loci around dhps to investigate the genetic lineages of the mutant dhps alleles in different parts of the country. Eighty-one of these samples had mutant dhps alleles, of which 62 were from Andaman and Nicobar Islands and the remaining 19 were from mainland India. Of 112 isolates with a wild-type dhps allele, 109 were from mainland India and only 3 were from Andaman and Nicobar Islands. Consistent with the model of selection, the mean expected heterozygosity (H(e)) around mutant dhps alleles (H(e) = 0.55; n = 81) associated with sulfadoxine resistance was lower (P ≤ 0.05) than the mean H(e) around the wild-type dhps allele (H(e) = 0.80; n = 112). There was more genetic diversity in flanking microsatellites of dhps than dhfr among these isolates, which confirms the assertion that dhps mutations are at a very early stage of fixation in the parasite population. Microsatellite haplotypes around various mutant dhps alleles suggest that the resistant dhps alleles have multiple independent origins in India, especially in Andaman and Nicobar Islands. Determining the genetic lineages of the resistant dhps alleles on Andaman and Nicobar Islands and mainland India is significant, given the role of Asia in the intercontinental spread of chloroquine

  13. Gamma ray irradiation inhibits Plasmodium falciparum multiplication in in vitro culture supplemented with tritium labeled hypoxanthine

    Directory of Open Access Journals (Sweden)

    HARRY NUGROHO EKO SURNIYANTORO

    2016-04-01

    Full Text Available Abstract. Surniyantoro HNE, Darlina, Nurhayati S, Tetriana D, Syaifudin M. 2015. Gamma ray irradiation inhibits Plasmodium falciparum multiplication in in vitro culture supplemented with tritium labeled hypoxanthine. Nusantara Bioscience 8: 8-13. Malaria remains a major public health threat in the world. Therefore an attempt to create malaria vaccine for supporting the control of disease was taken by attenuating parasites with gamma rays and it was proven effective based on microscopic observation. Objective of this research was to assess the effectiveness of gamma rays to attenuate malaria parasites based on isotopic method. A laboratory strain of P. falciparum (3D7 was in vitro cultured with standard procedure and it was irradiated with gamma rays at doses of 150-250 Gy and unirradiated parasites served as control. Twenty four hours after 1-2 µCi of 3H-hypoxanthine was added into culture 100 µl of medium was taken and was repeated at various times, then hypoxanthine incorporation was measured with beta counter. Microscopic observation of parasitemia in culture was also done. The results showed that there was a fluctuation in multiplication of parasites post irradiation mainly in higher dose (more than150 Gy. Irradiated of parasites were more active in incorporate with purine precursor up to 48 hours. Parasites returned to their highest activity at 116 hours after hypoxanthine addition. No significant difference was found among doses of irradiation with p of 0.05. This was quite different with the finding from microscopic observation. It was known that dose of 150 Gy was the most effective dose for inhibiting of the parasite multiplication where some factors affecting these facts.

  14. Optimizing the HRP-2 In Vitro Malaria Drug Susceptibility Assay Using a Reference Clone to Improve Comparisons of Plasmodium falciparum Field Isolates

    Science.gov (United States)

    2012-09-13

    available soon. Optimizing the HRP-2 in vitro malaria drug susceptibility assay using a reference clone to improve comparisons of Plasmodium falciparum...Optimizing the HRP-2 in vitro malaria drug susceptibility assay using a reference clone to improve comparisons of Plasmodium falciparum field isolates 5a...Date: 13 September 2012 14. ABSTRACT Apparent emerging artemisinin-resistant Plasmodium falciparum malaria in Southeast Asia requires development

  15. Naturally acquired antibodies to the glutamate-rich protein are associated with protection against Plasmodium falciparum malaria

    DEFF Research Database (Denmark)

    Dodoo, D; Theisen, M; Kurtzhals, J A

    2000-01-01

    of the Plasmodium falciparum glutamate-rich protein (GLURP). The data show that levels of the GLURP-specific IgG that occurs in the nonrepeat region of the antigen are significantly correlated with clinical protection from P. falciparum malaria, after correction for the confounding effect of age. Furthermore...

  16. Plasmodium falciparum avoids change in erythrocytic surface expression of phagocytosis markers during inhibition of nitric oxide synthase activity

    DEFF Research Database (Denmark)

    Hempel, Casper; Kohnke, Hannes; Maretty, Lasse

    2014-01-01

    Nitric oxide (NO) accumulates in Plasmodium falciparum-infected erythrocytes. It may be produced by a parasite NO synthase (NOS) or by nitrate reduction. The parasite's benefit of NO accumulation is not understood. We investigated if inhibiting the P. falciparum NOS with specific and unspecific N...

  17. Regulation of antigenic variation in Plasmodium falciparum: censoring freedom of expression?

    Science.gov (United States)

    Duffy, Michael F; Reeder, John C; Brown, Graham V

    2003-03-01

    Plasmodium falciparum employs a strategy of clonal antigenic variation to evade the host immune response during the intraerythrocytic stage of its life cycle. The major variant parasite molecule is the P. falciparum erythrocyte membrane protein (PfEMP)1, which is encoded by the var multigene family. The parasite switches between different PfEMP1 molecules through regulation of var transcription. Recent studies have shed considerable light on this process, but much remains unknown. However, striking parallels between transcriptional control of var and genes in other organisms provide direction for future studies.

  18. In vitro cytocidal effect of novel lytic peptides on Plasmodium falciparum and Trypanosoma cruzi.

    Science.gov (United States)

    Jaynes, J M; Burton, C A; Barr, S B; Jeffers, G W; Julian, G R; White, K L; Enright, F M; Klei, T R; Laine, R A

    1988-10-01

    Plasmodium falciparum and Trypanosoma cruzi were killed by two novel lytic peptides (SB-37 and Shiva-1) in vitro. Human erythrocytes infected with P. falciparum, and Vero cells infected with T. cruzi, were exposed to these peptides. The result, in both cases, was a significant decrease in the level of parasite infection. Furthermore, the peptides had a marked cytocidal effect on trypomastigote stages of T. cruzi in media, whereas host eukaryotic cells were unaffected by the treatments. In view of the worldwide prevalence of these protozoan diseases and the lack of completely suitable treatments, lytic peptides may provide new and unique chemotherapeutic agents for the treatment of these infections.

  19. 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...... the reverse was seen with respect to Hp2-1 and Hp2-2. Our data suggest that the Hp1-1 phenotype is associated with susceptibility to P. falciparum malaria in general, and to the development of severe disease in particular....

  20. The implication of dihydrofolate reductase and dihydropteroate synthetase gene mutations in modification of Plasmodium falciparum characteristics

    DEFF Research Database (Denmark)

    A-Elbasit, Ishraga E; Alifrangis, Michael; Khalil, Insaf F

    2007-01-01

    the effects of dhfr/dhps mutations on parasite characteristics other than SP resistance. METHOD: Parasite infections obtained from 153 Sudanese patients with uncomplicated falciparum malaria treated with SP or SP + chloroquine, were successfully genotyped at nine codons in the dhfr/dhps genes by PCR......BACKGROUND: The Plasmodium falciparum dihydrofolate reductase (DHFR) and dihydropteroate synthetase (DHPS) are enzymes of central importance in parasite metabolism. The dhfr and dhps gene mutations are known to be associated with sulphadoxine/pyrimethamine (SP) resistance. OBJECTIVE: To investigate...

  1. 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...

  2. 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

    , PfRh2a and PfRh2b and IgG3 response for PfRh2a were also negatively correlated with parasitaemia. Conclusions: These data suggest that falciparum malaria patients who develop clinical immunity (asymptomatic parasitaemia) in a low transmission setting such as the Peruvian Amazon have antibody......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 naturally...

  3. Plasmodium falciparum malaria occurring four years after leaving an endemic area.

    Science.gov (United States)

    Vantomme, B; Van Acker, J; Rogge, S; Ommeslag, D; Donck, J; Callens, S

    2016-04-01

    We present a case of a 52-year-old woman of Ghanaian origin who developed Plasmodium falciparum malaria 4 years after leaving Africa. She had not returned to an endemic area since. We hypothesize several possible scenarios to explain this infection, of which we believe recrudescence of P. falciparum is the most plausible. This occurred most likely as a consequence of waning immunity several years after leaving a high-transmission area. She recovered after a 3-day treatment with atovaquone/proguanil.

  4. Comparison of different PCR protocols for the detection and diagnosis of Plasmodium falciparum.

    Science.gov (United States)

    Oster, N; Abdel-Aziz, I Z; Stich, A; Coulibaly, B; Kouyatè, B; Andrews, K T; McLean, J E; Lanzer, M

    2005-11-01

    An assessment of differing PCR protocols for the diagnosis of Plasmodium falciparum infection was performed on samples from an area of holoendemic malaria transmission in western Burkina Faso. The PCR protocols had generally high sensitivities (>92%) and specificities (>69%), but the negative predictive values (NPV) were moderate and differed widely among the PCR protocols tested. These PCR protocols that amplified either the P. falciparum pfcrt gene or the small subunit ribosomal DNA were the most reliable diagnostic tools. However, the moderate NPV imply that more than one PCR protocol should be used for diagnosis in holoendemic areas.

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

    OpenAIRE

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

    1982-01-01

    An ELISA method has been developed for the diagnosis of Plasmodium falciparum infection in man. Parasites from in vitro cultures of P. falciparum were used as source of antigen for the solid phase and the source of specific antibody was immune Gambian sera; binding of antibody in antigen-coated wells was registered by means of alkaline phosphatase-conjugated anti-human IgG. Parasites were detected on the basis of inhibition of antibody-binding. The test was applied to the detection of parasit...

  6. 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...... dihydrofolate reductase and dihydropteroate synthetase genes. During September 2008-October 2010, we monitored a cohort of 924 pregnant women in an area of Tanzania with declining malaria transmission. P. falciparum parasites were genotyped, and the effect of infecting haplotypes on birthweight was assessed...

  7. Overlapping antigenic repertoires of variant antigens expressed on the surface of erythrocytes infected by Plasmodium falciparum

    DEFF Research Database (Denmark)

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

    1999-01-01

    Antibodies against variable antigens expressed on the surface of Plasmodium falciparum-infected erythrocytes are believed to be important for protection against malaria. A target for these antibodies is the P. falciparum erythrocyte membrane protein 1, PfEMP1, which is encoded by around 50 var...... genes and undergoes clonal variation. Using agglutination and mixed agglutination tests and flow cytometry to analyse the recognition of variant antigens on parasitized erythrocytes by plasma antibodies from individuals living in Daraweesh in eastern Sudan, an area of seasonal and unstable malaria...

  8. Two cases of Plasmodium falciparum malaria in the Netherlands without recent travel to a malaria-endemic country.

    Science.gov (United States)

    Arends, Joop E; Oosterheert, Jan Jelrik; Kraaij-Dirkzwager, Marleen M; Kaan, Jan A; Fanoy, Ewout B; Haas, Pieter-Jan; Scholte, Ernst-Jan; Kortbeek, Laetitia M; Sankatsing, Sanjay U C

    2013-09-01

    Recently, two patients of African origin were given a diagnosis of Plasmodium falciparum malaria without recent travel to a malaria-endemic country. This observation highlights the importance for clinicians to consider tropical malaria in patients with fever. Possible transmission routes of P. falciparum to these patients will be discussed. From a public health perspective, international collaboration is crucial when potential cases of European autochthonous P. falciparum malaria in Europe re considered.

  9. Prevalence of molecular markers of anti-malarial drug resistance in Plasmodium vivax and Plasmodium falciparum in two districts of Nepal

    DEFF Research Database (Denmark)

    Ranjitkar, Samir; Schousboe, Mette L; Thomsen, Thomas

    2011-01-01

    ABSTRACT: BACKGROUND: Sulphadoxine-pyrimethamine (SP) and chloroquine (CQ) have been used in treatment of falciparum and vivax malaria in Nepal. Recently, resistance to both drugs have necessitated a change towards artemisinin combination therapy (ACT) against Plasmodium falciparum in highly...... endemic areas. However, SP is still used against P. falciparum infections in low endemic areas while CQ is used in suspected cases in areas with lack of diagnostic facilities. This study examines the prevalence of molecular markers of P. falciparum and Plasmodium vivax CQ and SP resistance to determine...... if high levels of in vivo resistance are reflected at molecular level as well. METHODS: Finger prick blood samples (n=189) were collected from malaria positive patients from two high endemic districts and analysed for single nucleotide polymorphisms (SNPs) in the resistance related genes of P. falciparum...

  10. 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

  11. 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.

  12. 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.

  13. An innovative shape equation to quantify the morphological characteristics of parasitized red blood cells by Plasmodium falciparum and Plasmodium vivax.

    Science.gov (United States)

    Karimi, Alireza; Navidbakhsh, Mahdi; Motevalli Haghi, Afsaneh; Faghihi, Shahab

    2013-04-01

    The morphology of red blood cells is affected significantly during maturation of malaria parasites, Plasmodium falciparum and Plasmodium vivax. A novel shape equation is presented that defines shape of parasitized red blood cells by P. falciparum (Pf-red blood cells) and P. vivax (Pv-red blood cells) at four stages of infection. The Giemsa-stained thin blood films are prepared using blood samples collected from healthy donors, patients having P. falciparum and P. vivax malaria. The diameter and thickness of healthy red blood cells plus Pf-red blood cells and Pv-red blood cells at each stage of infection are measured from their optical images using Olysia and Scanning Probe Image Processor softwares, respectively. Using diameters and thicknesses of parasitized red blood cells, a shape equation is fitted and relative two-dimensional shapes are plotted using MATHEMATICA. The shape of Pf-red blood cell drastically changes at ring stage as its thickness increases by 82%, while Pv-red blood cell remains biconcave (30% increase in thickness). By trophozoite and subsequent schizont stage, the Pf-red blood cell entirely loses its biconcave shape and becomes near spherical (diameter and thickness of ~8 µm). The Pv-red blood cell remains biconcave throughout the parasite development even though its volume increases. These results could have practical use for faster diagnosis, prediction, and treatment of human malaria and sickle-cell diseases.

  14. Susceptibility of two karyotypic forms of Anopheles aconitus (Diptera: Culicidae to Plasmodium falciparum and P. vivax Suscetibilidade de duas formas cariotípicas de Anopheles aconitus (Diptera: Culicidae a Plasmodium falciparum e P. vivax

    Directory of Open Access Journals (Sweden)

    Anuluck Junkum

    2005-12-01

    Full Text Available Four laboratory-raised colonies of two karyotypic forms of Anopheles aconitus, i.e., Form B (Chiang Mai and Phet Buri strains and C (Chiang Mai and Mae Hong Son strains, were experimentally infected with Plasmodium falciparum and P. vivax using an artificial membrane feeding technique and dissected eight and 12 days after feeding for oocyst and sporozoite rates, respectively. The results revealed that An. aconitus Form B and C were susceptible to P. falciparum and P. vivax, i.e., Form B (Chiang Mai and Phet Buri strains/P. falciparum and P. vivax and Form C (Chiang Mai and Mae Hong Son strains/P. vivax. Comparative statistical analyses of the oocyst rates, average number of oocysts per infected midgut and sporozoite rates among all strains of An. aconitus Form B and C to the ingroup control vectors, An. minimus A and C, exhibited mostly no significant differences, confirming the high potential vector of the two Plasmodium species. The sporozoite-like crystals found in the median lobe of the salivary glands, which could be a misleading factor in the identification of true sporozoites in salivary glands were found in both An. aconitus Form B and C.Quatro colônias desenvolvidas em laboratório, de duas formas cariotípicas de Anopheles aconitus i.e. forma B (cepa Chiang Mai e Phet Buri e C (Cepa Chiang Mai e Mae Hong Son, foram infectadas experimentalmente com Plasmodium falciparum e P. vivax usando técnica de alimentação com membrana artificial e dissecados oito e 12 dias após alimentação da média de oocistos e esporozoitos, respectivamente. Os resultados revelaram que An. aconitus formas B e C foram suscetíveis ao P. falciparum e P. vivax isto é, forma B (cepa Chiang Mai e Phet Buri/P. falciparum e P. vivax e forma C (cepa Chiang Mai e Mae Hong Son/P. vivax. Análises estatísticas comparativas das taxas de oocistos, número médio de oocistos por intestino médio infectado e taxas de esporozoitos entre todas as cepas de An. aconitus

  15. Characterization of immunoglobulin G antibodies to Plasmodium falciparum sporozoite surface antigen MB2 in malaria exposed individuals

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    John Chandy C

    2009-10-01

    Full Text Available Abstract Background MB2 protein is a sporozoite surface antigen on the human malaria parasite Plasmodium falciparum. MB2 was identified by screening a P. falciparum sporozoite cDNA expression library using immune sera from a protected donor immunized via the bites of P. falciparum-infected irradiated mosquitoes. It is not known whether natural exposure to P. falciparum also induces the anti-MB2 response and if this response differs from that in protected individuals immunized via the bites of P. falciparum infected irradiated mosquitoes. The anti-MB2 antibody response may be part of a robust protective response against the sporozoite. Methods Fragments of polypeptide regions of MB2 were constructed as recombinant fusions sandwiched between glutathione S-transferase and a hexa histidine tag for bacterial expression. The hexa histidine tag affinity purified proteins were used to immunize rabbits and the polyclonal sera evaluated in an in vitro inhibition of sporozoite invasion assay. The proteins were also used in immunoblots with sera from a limited number of donors immunized via the bites of P. falciparum infected irradiated mosquitoes and plasma and serum obtained from naturally exposed individuals in Kenya. Results Rabbit polyclonal antibodies targeting the non-repeat region of the basic domain of MB2 inhibited sporozoites entry into HepG2-A16 cells in vitro. Analysis of serum from five human volunteers that were immunized via the bites of P. falciparum infected irradiated mosquitoes that developed immunity and were completely protected against subsequent challenge with non-irradiated parasite also had detectable levels of antibody against MB2 basic domain. In contrast, in three volunteers not protected, anti-MB2 antibodies were below the level of detection. Sera from protected volunteers preferentially recognized a non-repeat region of the basic domain of MB2, whereas plasma from naturally-infected individuals also had antibodies that

  16. A Plasmodium falciparum copper-binding membrane protein with copper transport motifs

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    Choveaux David L

    2012-11-01

    Full Text Available Abstract Background Copper is an essential catalytic co-factor for metabolically important cellular enzymes, such as cytochrome-c oxidase. Eukaryotic cells acquire copper through a copper transport protein and distribute intracellular copper using molecular chaperones. The copper chelator, neocuproine, inhibits Plasmodium falciparum ring-to-trophozoite transition in vitro, indicating a copper requirement for malaria parasite development. How the malaria parasite acquires or secretes copper still remains to be fully elucidated. Methods PlasmoDB was searched for sequences corresponding to candidate P. falciparum copper-requiring proteins. The amino terminal domain of a putative P. falciparum copper transport protein was cloned and expressed as a maltose binding fusion protein. The copper binding ability of this protein was examined. Copper transport protein-specific anti-peptide antibodies were generated in chickens and used to establish native protein localization in P. falciparum parasites by immunofluorescence microscopy. Results Six P. falciparum copper-requiring protein orthologs and a candidate P. falciparum copper transport protein (PF14_0369, containing characteristic copper transport protein features, were identified in PlasmoDB. The recombinant amino terminal domain of the transport protein bound reduced copper in vitro and within Escherichia coli cells during recombinant expression. Immunolocalization studies tracked the copper binding protein translocating from the erythrocyte plasma membrane in early ring stage to a parasite membrane as the parasites developed to schizonts. The protein appears to be a PEXEL-negative membrane protein. Conclusion Plasmodium falciparum parasites express a native protein with copper transporter characteristics that binds copper in vitro. Localization of the protein to the erythrocyte and parasite plasma membranes could provide a mechanism for the delivery of novel anti-malarial compounds.

  17. Genetic diversity and population structure of Plasmodium falciparum in Thailand, a low transmission country

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    Sitthi-amorn Chitr

    2009-07-01

    Full Text Available Abstract Background The population structure of the causative agents of human malaria, Plasmodium sp., including the most serious agent Plasmodium falciparum, depends on the local epidemiological and demographic situations, such as the incidence of infected people, the vector transmission intensity and migration of inhabitants (i.e. exchange between sites. Analysing the structure of P. falciparum populations at a large scale, such as continents, or with markers that are subject to non-neutral selection, can lead to a masking and misunderstanding of the effective process of transmission. Thus, knowledge of the genetic structure and organization of P. falciparum populations in a particular area with neutral genetic markers is needed to understand which epidemiological factors should be targeted for disease control. Limited reports are available on the population genetic diversity and structure of P. falciparum in Thailand, and this is of particular concern at the Thai-Myanmar and Thai-Cambodian borders, where there is a reported high resistance to anti-malarial drugs, for example mefloquine, with little understanding of its potential gene flow. Methods The diversity and genetic differentiation of P. falciparum populations were analysed using 12 polymorphic apparently neutral microsatellite loci distributed on eight of the 14 different chromosomes. Samples were collected from seven provinces in the western, eastern and southern parts of Thailand. Results A strong difference in the nuclear genetic structure was observed between most of the assayed populations. The genetic diversity was comparable to the intermediate level observed in low P. falciparum transmission areas (average HS = 0.65 ± 0.17, where the lowest is observed in South America and the highest in Africa. However, uniquely the Yala province, had only a single multilocus genotype present in all samples, leading to a strong geographic differentiation when compared to the other Thai

  18. Identification of a mutant PfCRT-mediated chloroquine tolerance phenotype in Plasmodium falciparum.

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    Stephanie G Valderramos

    2010-05-01

    Full Text Available Mutant forms of the Plasmodium falciparum transporter PfCRT constitute the key determinant of parasite resistance to chloroquine (CQ, the former first-line antimalarial, and are ubiquitous to infections that fail CQ treatment. However, treatment can often be successful in individuals harboring mutant pfcrt alleles, raising questions about the role of host immunity or pharmacokinetics vs. the parasite genetic background in contributing to treatment outcomes. To examine whether the parasite genetic background dictates the degree of mutant pfcrt-mediated CQ resistance, we replaced the wild type pfcrt allele in three CQ-sensitive strains with mutant pfcrt of the 7G8 allelic type prevalent in South America, the Oceanic region and India. Recombinant clones exhibited strain-dependent CQ responses that ranged from high-level resistance to an incremental shift that did not meet CQ resistance criteria. Nonetheless, even in the most susceptible clones, 7G8 mutant pfcrt enabled parasites to tolerate CQ pressure and recrudesce in vitro after treatment with high concentrations of CQ. 7G8 mutant pfcrt was found to significantly impact parasite responses to other antimalarials used in artemisinin-based combination therapies, in a strain-dependent manner. We also report clinical isolates from French Guiana that harbor mutant pfcrt, identical or related to the 7G8 haplotype, and manifest a CQ tolerance phenotype. One isolate, H209, harbored a novel PfCRT C350R mutation and demonstrated reduced quinine and artemisinin susceptibility. Our data: 1 suggest that high-level CQR is a complex biological process dependent on the presence of mutant pfcrt; 2 implicate a role for variant pfcrt alleles in modulating parasite susceptibility to other clinically important antimalarials; and 3 uncover the existence of a phenotype of CQ tolerance in some strains harboring mutant pfcrt.

  19. A Plasmodium falciparum FcB1-schizont-EST collection providing clues to schizont specific gene structure and polymorphism

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    Charneau Sébastien

    2009-05-01

    Full Text Available Abstract Background The Plasmodium falciparum genome (3D7 strain published in 2002, revealed ~5,400 genes, mostly based on in silico predictions. Experimental data is therefore required for structural and functional assessments of P. falciparum genes and expression, and polymorphic data are further necessary to exploit genomic information to further qualify therapeutic target candidates. Here, we undertook a large scale analysis of a P. falciparum FcB1-schizont-EST library previously constructed by suppression subtractive hybridization (SSH to study genes expressed during merozoite morphogenesis, with the aim of: 1 obtaining an exhaustive collection of schizont specific ESTs, 2 experimentally validating or correcting P. falciparum gene models and 3 pinpointing genes displaying protein polymorphism between the FcB1 and 3D7 strains. Results A total of 22,125 clones randomly picked from the SSH library were sequenced, yielding 21,805 usable ESTs that were then clustered on the P. falciparum genome. This allowed identification of 243 protein coding genes, including 121 previously annotated as hypothetical. Statistical analysis of GO terms, when available, indicated significant enrichment in genes involved in "entry into host-cells" and "actin cytoskeleton". Although most ESTs do not span full-length gene reading frames, detailed sequence comparison of FcB1-ESTs versus 3D7 genomic sequences allowed the confirmation of exon/intron boundaries in 29 genes, the detection of new boundaries in 14 genes and identification of protein polymorphism for 21 genes. In addition, a large number of non-protein coding ESTs were identified, mainly matching with the two A-type rRNA units (on chromosomes 5 and 7 and to a lower extent, two atypical rRNA loci (on chromosomes 1 and 8, TARE subtelomeric regions (several chromosomes and the recently described telomerase RNA gene (chromosome 9. Conclusion This FcB1-schizont-EST analysis confirmed the actual expression of 243

  20. Purification and characterization of recombinant Plasmodium falciparum adenylosuccinate synthetase expressed in Escherichia coli.

    Science.gov (United States)

    Jayalakshmi, R; Sumathy, K; Balaram, Hemalatha

    2002-06-01

    Most parasitic protozoa lack the de novo purine biosynthetic pathway and rely exclusively on the salvage pathway for their purine nucleotide requirements. Enzymes of the salvage pathway are, therefore, candidate drug targets. We have cloned the Plasmodium falciparum adenylosuccinate synthetase gene. In the parasite, adenylosuccinate synthetase is involved in the synthesis of AMP from IMP formed during the salvage of the purine base, hypoxanthine. The gene was shown to code for a functionally active protein by functional complementation in a purA mutant strain of Escherichia coli, H1238. This paper reports the conditions for hyperexpression of the recombinant protein in E. coli BL21(DE3) and purification of the protein to homogeneity. The enzyme was found to require the presence of dithiothreitol during the entire course of the purification for activity. Glycerol and EDTA were found to stabilize enzyme activity during storage. The specific activity of the purified protein was 1143.6 +/- 36.8 mUnits/mg. The K(M)s for the three substrates, GTP, IMP, and aspartate, were found to be 4.8 microM, 22.8 microM, and 1.4 mM, respectively. The enzyme was a dimer on gel filtration in buffers of low ionic strength but equilibrated between a monomer and a dimer in buffers of increased ionic strength.

  1. Synergy of four macrolide antibiotics with chloroquine against chloroquine-resistant Plasmodium falciparum in vitro.

    Science.gov (United States)

    Gershon, P; Howells, R E

    1986-01-01

    The antimalarial activity of four macrolide antibiotics was investigated against the multidrug resistant K1 strain of Plasmodium falciparum in vitro. ID50 (50% inhibitory concentration) values for erythromycin, spiramycin, tylosin tartrate and oleandomycin phosphate in 48-hour assays were 1.6 X 10(-4)M, 2.5 X 10(-5)M, 1.2 X 10(-5)M and 9 X 10(-6)M respectively, and in 96 hour assays were 10(-5)M, 2.6 X 10(-6)M, 2.6 X 10(-6) and 3 X 10(-6)M, respectively. Comparable values were obtained in assays in which drug effect was quantified from either parasite counts or 14C isoleucine incorporation. Each of the four macrolides displayed synergy with chloroquine at the IC90 (90% inhibitory concentration) level, but at the IC50 level synergy was either less pronounced or absent. For each combination this difference in the degree of synergy was significant at the 95% level of confidence. In replicate assays in which 3H hypoxanthine was the marker of drug effect, synergy between chloroquine and either erythromycin or spiramycin could not be detected.

  2. Characterization of a novel inhibitory human monoclonal antibody directed against Plasmodium falciparum Apical Membrane Antigen 1.

    Science.gov (United States)

    Maskus, Dominika J; Królik, Michał; Bethke, Susanne; Spiegel, Holger; Kapelski, Stephanie; Seidel, Melanie; Addai-Mensah, Otchere; Reimann, Andreas; Klockenbring, Torsten; Barth, Stefan; Fischer, Rainer; Fendel, Rolf

    2016-12-21

    Malaria remains a major challenge to global health causing extensive morbidity and mortality. Yet, there is no efficient vaccine and the immune response remains incompletely understood. Apical Membrane Antigen 1 (AMA1), a leading vaccine candidate, plays a key role during merozoite invasion into erythrocytes by interacting with Rhoptry Neck Protein 2 (RON2). We generated a human anti-AMA1-antibody (humAbAMA1) by EBV-transformation of sorted B-lymphocytes from a Ghanaian donor and subsequent rescue of antibody variable regions. The antibody was expressed in Nicotiana benthamiana and in HEK239-6E, characterized for binding specificity and epitope, and analyzed for its inhibitory effect on Plasmodium falciparum. The generated humAbAMA1 shows an affinity of 106-135 pM. It inhibits the parasite strain 3D7A growth in vitro with an expression system-independent IC50-value of 35 μg/ml (95% confidence interval: 33 μg/ml-37 μg/ml), which is three to eight times lower than the IC50-values of inhibitory antibodies 4G2 and 1F9. The epitope was mapped to the close proximity of the RON2-peptide binding groove. Competition for binding between the RON2-peptide and humAbAMA1 was confirmed by surface plasmon resonance spectroscopy measurements. The particularly advantageous inhibitory activity of this fully human antibody might provide a basis for future therapeutic applications.

  3. Identification, design and biological evaluation of heterocyclic quinolones targeting Plasmodium falciparum type II NADH:quinone oxidoreductase (PfNDH2).

    Science.gov (United States)

    Leung, Suet C; Gibbons, Peter; Amewu, Richard; Nixon, Gemma L; Pidathala, Chandrakala; Hong, W David; Pacorel, Bénédicte; Berry, Neil G; Sharma, Raman; Stocks, Paul A; Srivastava, Abhishek; Shone, Alison E; Charoensutthivarakul, Sitthivut; Taylor, Lee; Berger, Olivier; Mbekeani, Alison; Hill, Alasdair; Fisher, Nicholas E; Warman, Ashley J; Biagini, Giancarlo A; Ward, Stephen A; O'Neill, Paul M

    2012-03-08

    Following a program undertaken to identify hit compounds against NADH:ubiquinone oxidoreductase (PfNDH2), a novel enzyme target within the malaria parasite Plasmodium falciparum, hit to lead optimization led to identification of CK-2-68, a molecule suitable for further development. In order to reduce ClogP and improve solubility of CK-2-68 incorporation of a variety of heterocycles, within the side chain of the quinolone core, was carried out, and this approach led to a lead compound SL-2-25 (8b). 8b has IC(50)s in the nanomolar range versus both the enzyme and whole cell P. falciparum (IC(50) = 15 nM PfNDH2; IC(50) = 54 nM (3D7 strain of P. falciparum) with notable oral activity of ED(50)/ED(90) of 1.87/4.72 mg/kg versus Plasmodium berghei (NS Strain) in a murine model of malaria when formulated as a phosphate salt. Analogues in this series also demonstrate nanomolar activity against the bc(1) complex of P. falciparum providing the potential added benefit of a dual mechanism of action. The potent oral activity of 2-pyridyl quinolones underlines the potential of this template for further lead optimization studies.

  4. Inhibitory monoclonal antibody against a (myristylated) small-molecular-weight antigen from Plasmodium falciparum associated with the parasitophorous vacuole membrane.

    Science.gov (United States)

    Kara, U A; Stenzel, D J; Ingram, L T; Bushell, G R; Lopez, J A; Kidson, C

    1988-04-01

    A small-molecular-weight antigen that occurs in asexual blood stages in synchronized cultures of Plasmodium falciparum was detected by a monoclonal antibody which inhibits parasite growth in vitro. This antigen, QF116, showed a molecular weight of 15,000 in parasite strain FCR-3K+ from The Gambia and 19,000 in strain FCQ-27 from Papua New Guinea. The protein did not show significant glycosylation by galactose or glucosamine labeling but was found to be acylated by myristic acid. By using immunogold labeling and electron microscopy, the location of the antigen could be attributed to the parasitophorous vacuole membrane and to inclusions and vesicles residing within the cytoplasm of the erythrocyte host cell.

  5. Protection of aouts monkeys after immunization with recombinant antigens of Plasmodium falciparum

    Directory of Open Access Journals (Sweden)

    Burhard Enders

    1992-01-01

    Full Text Available The genus Aotus spp. (owl monkey is one of the WHO recommended experimental models for Plasmodium falciparum blood stage infection, especially relevant for vaccination studies with asexual blood stage antigens of this parasite. For several immunization trials with purified recombinant merozoite/schizont antigens, the susceptible Aouts kenotypes II, III, IV and VI were immunized with Escherichia coli derived fusion proteins containg partial sequences of the proteins MSAI (merozoite surface antigen I, SERP (serine-strech protein and HRPII (histidine alanine rich protein II as well as with a group of recombinant antigens obtained by an antiserum raised against a protective 41 kD protein band. The subcutaneous application (3x of the antigen preparations was carried out in intact animals followed by splenectomy prior to challange, in order to increase the susceptibility of the experimental hosts to the parasite. A partial sequence of HRPII, the combination of three different fusion proteins of the 41 kD group and mixture of two sequences of SERP in the presence of the modified Al(OH3 adjuvant conferred significant protection against a challange infection with P. falciparum blood stages (2-5 x 10 (elevado a sexta potência i. RBC. Monkey immunized with the MS2-fusion protein carrying the N-terminal part of the 195 kD precursor of the major merozoite surface antigens induced only marginal protection showing some correlation between antibody titer and degree of parasitaemia. Based on the protective capacity of these recombinant antigens we have expressed two hybrid proteins (MS2/SERP/HRPII and SERP/MSAI/HRPII in E. coli containing selected partial sequences of SERP, HRPII and MSAI. Antibodies raised against both hybrid proteins in rabbits and Aotus monkeys recognize the corresponding schizont polypeptides. In two independent immunization trials using 13 animals (age 7 months to 3 years we could show that immunization of Aotus monkeys with either of the

  6. Plasmodium falciparum Choline Kinase Inhibition Leads to a Major Decrease in Phosphatidylethanolamine Causing Parasite Death

    Science.gov (United States)

    Serrán-Aguilera, Lucía; Denton, Helen; Rubio-Ruiz, Belén; López-Gutiérrez, Borja; Entrena, Antonio; Izquierdo, Luis; Smith, Terry K.; Conejo-García, Ana; Hurtado-Guerrero, Ramon

    2016-01-01

    Malaria is a life-threatening disease caused by different species of the protozoan parasite Plasmodium, with P. falciparum being the deadliest. Increasing parasitic resistance to existing antimalarials makes the necessity of novel avenues to treat this disease an urgent priority. The enzymes responsible for the synthesis of phosphatidylcholine and phosphatidylethanolamine are attractive drug targets to treat malaria as their selective inhibition leads to an arrest of the parasite’s growth and cures malaria in a mouse model. We present here a detailed study that reveals a mode of action for two P. falciparum choline kinase inhibitors both in vitro and in vivo. The compounds present distinct binding modes to the choline/ethanolamine-binding site of P. falciparum choline kinase, reflecting different types of inhibition. Strikingly, these compounds primarily inhibit the ethanolamine kinase activity of the P. falciparum choline kinase, leading to a severe decrease in the phosphatidylethanolamine levels within P. falciparum, which explains the resulting growth phenotype and the parasites death. These studies provide an understanding of the mode of action, and act as a springboard for continued antimalarial development efforts selectively targeting P. falciparum choline kinase. PMID:27616047

  7. International funding for malaria control in relation to populations at risk of stable Plasmodium falciparum transmission.

    OpenAIRE

    Snow, Robert W; Guerra, Carlos A; Mutheu, Juliette J; Simon I Hay

    2008-01-01

    Editors' Summary Background. Malaria is one of the most common infectious diseases in the world and one of the greatest global public health problems. The Plasmodium falciparum parasite causes approximately 500 million cases each year and over one million deaths. More than 40% of the world's population is at risk of malaria. The Millennium Development Goals (MDGs), established by the United Nations in 2000, include a target in Goal 6: ?to have halted by 2015 and begun to reverse the incidence...

  8. Purification of Components of the Translation Elongation Factor Complex of Plasmodium falciparum by Tandem Affinity Purification▿

    OpenAIRE

    2007-01-01

    Plasmodium falciparum is the causative agent of severe human malaria, responsible for over 2 million deaths annually. Of the 5,300 polypeptides predicted to control the parasite life cycle in mosquitoes and humans, 60% are of unknown function. A major challenge of malaria postgenomic biology is to understand how the 5,300 predicted proteins coexist and interact to perform the essential tasks that define the complex life cycle of the parasite. One approach to assign function to these proteins ...

  9. Complement Receptor 1 Is a Sialic Acid-Independent Erythrocyte Receptor of Plasmodium falciparum

    Science.gov (United States)

    2010-06-17

    Walter Reed Army Institute of Research, Silver Spring, Maryland, United States of America, 5 Department of Parasitology , Division of Experimental... parasite of humans. A major portion of its life cycle is dedicated to invading and multiplying inside erythrocytes. The molecular mechanisms of...Sciences, Bethesda, MD, ...... 14. ABSTRACT Plasmodium falciparum is a highly lethal malaria parasite of humans. A major portion of its life cycle is

  10. Efficient CRISPR-Cas9–mediated genome editing in Plasmodium falciparum

    OpenAIRE

    Wagner, Jeffrey C; Platt, Randall J.; Goldfless, Stephen J.; ZHANG Feng; Niles, Jacquin C.

    2014-01-01

    Malaria is a major cause of global morbidity and mortality, and new strategies for treating and preventing this disease are needed. Here we show that the Streptococcus pyogenes Cas9 DNA endonuclease and single guide RNAs (sgRNAs) produced using T7 RNA polymerase (T7 RNAP) efficiently edit the Plasmodium falciparum genome. Targeting the genes encoding native knob-associated histidine-rich protein (kahrp) and erythrocyte binding antigen 175 (eba-175), we achieved high (≥50–100%) gene disruption...

  11. A redesigned CRISPR/Cas9 system for marker-free genome editing in Plasmodium falciparum

    OpenAIRE

    Lu, Junnan; TONG, Ying; Pan, Jiaqiang; Yang, Yijun; Liu, Quan; Tan, Xuefang; Zhao, Siting; Qin, Li; Chen, Xiaoping

    2016-01-01

    Background A highly efficient CRISPR/Cas9-based marker-free genome editing system has been established in Plasmodium falciparum (Pf). However, with the current methods, two drug-selectable markers are needed for episome retention, which may present hurdles for consecutive genome manipulations due to the limited number of available selectable markers. The loading capacity of donor DNA is also unsatisfactory due to the large size of the Cas9 nuclease and sgRNA co-expression system, which limits...

  12. Nanovaccines for Malaria Using Plasmodium falciparum Antigen Pfs25 Attached Gold Nanoparticles

    OpenAIRE

    Kumar, Rajesh; Ray, Paresh C; Datta, Dibyadyuti; Bansal, Geetha P.; Angov, Evelina; Kumar, Nirbhay

    2015-01-01

    Malaria transmission-blocking vaccines (TBV) targeting sexual stages of the parasite represent an ideal intervention to reduce the burden of the disease and eventual elimination at the population level in endemic regions. Immune responses against sexual stage antigens impair the development of parasite inside the mosquitoes. Target antigens identified in Plasmodium falciparum include surface proteins Pfs230 and Pfs48/45 in male and female gametocytes and Pfs25 expressed in zygotes and ookinet...

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

    Science.gov (United States)

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

    2010-05-01

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

  14. 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.

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

    Science.gov (United States)

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

    2006-06-01

    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 observed upon incubation of synchronous parasite cultures in the presence of the triterpenoids, and when the parasite cultures were grown in a triterpenoid-free medium with erythrocytes preloaded with the triterpenoids.

  16. Common variation in the ABO glycosyltransferase is associated with susceptibility to severe Plasmodium falciparum malaria

    OpenAIRE

    Fry, Andrew E.; Griffiths, Michael J.; Auburn, Sarah; Diakite, Mahamadou; Forton, Julian T.; Green, Angela; Richardson, Anna; Wilson, Jonathan; Jallow, Muminatou; Sisay-Joof, Fatou; Pinder, Margaret; Peshu, Norbert; Williams, Thomas N.; Marsh, Kevin; Malcolm E Molyneux

    2007-01-01

    There is growing epidemiological and molecular evidence that ABO blood group affects host susceptibility to severe Plasmodium falciparum infection. The high frequency of common ABO alleles means that even modest differences in susceptibility could have a significant impact on the health of people living in malaria endemic regions. We performed an association study, the first to utilize key molecular genetic variation underlying the ABO system, genotyping >9000 individuals across 3 African pop...

  17. Nanovaccines for Malaria Using Plasmodium falciparum Antigen Pfs25 Attached Gold Nanoparticles

    OpenAIRE

    kumar, Rajesh; Ray, Paresh C.; Datta, Dibyadyuti; Bansal, Geetha P.; Angov, Evelina; Kumar, Nirbhay

    2015-01-01

    Malaria transmission-blocking vaccines (TBV) targeting sexual stages of the parasite represent an ideal intervention to reduce the burden of the disease and eventual elimination at the population level in endemic regions. Immune responses against sexual stage antigens impair the development of parasite inside the mosquitoes. Target antigens identified in Plasmodium falciparum include surface proteins Pfs230 and Pfs48/45 in male and female gametocytes and Pfs25 expressed in zygotes and ookinet...

  18. A Plasmodium falciparum copper-binding membrane protein with copper transport motifs

    OpenAIRE

    Choveaux David L; Przyborski Jude M; Goldring JP

    2012-01-01

    Abstract Background Copper is an essential catalytic co-factor for metabolically important cellular enzymes, such as cytochrome-c oxidase. Eukaryotic cells acquire copper through a copper transport protein and distribute intracellular copper using molecular chaperones. The copper chelator, neocuproine, inhibits Plasmodium falciparum ring-to-trophozoite transition in vitro, indicating a copper requirement for malaria parasite development. How the malaria parasite acquires or secretes copper st...

  19. VAR2CSA expression on the surface of placenta-derived Plasmodium falciparum-infected erythrocytes

    DEFF Research Database (Denmark)

    Magistrado, Pamela; Salanti, Ali; Tuikue Ndam, Nicaise G;

    2008-01-01

    Malaria remains a major threat, in sub-Saharan Africa primarily, and the most deadly infections are those with Plasmodium falciparum. Pregnancy-associated malaria is a clinically important complication of infection; it results from a unique interaction between proteoglycans in the placental inter...... on the surface of infected erythrocytes from placenta. Importantly, this was achieved with cross-reactive antibodies against VAR2CSA....

  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.

  1. Regulation of Plasmodium falciparum Glideosome Associated Protein 45 (PfGAP45) Phosphorylation

    OpenAIRE

    Divya Catherine Thomas; Anwar Ahmed; Tim Wolf Gilberger; Pushkar Sharma

    2012-01-01

    The actomyosin motor complex of the glideosome provides the force needed by apicomplexan parasites such as Toxoplasma gondii (Tg) and Plasmodium falciparum (Pf) to invade their host cells and for gliding motility of their motile forms. Glideosome Associated Protein 45 (PfGAP45) is an essential component of the glideosome complex as it facilitates anchoring and effective functioning of the motor. Dissection of events that regulate PfGAP45 may provide insights into how the motor and the glideos...

  2. High Yield Purification of Plasmodium falciparum Merozoites For Use in Opsonizing Antibody Assays

    OpenAIRE

    Hill, Danika L.; Eriksson, Emily M.; Schofield, Louis

    2014-01-01

    Plasmodium falciparum merozoite antigens are under development as potential malaria vaccines. One aspect of immunity against malaria is the removal of free merozoites from the blood by phagocytic cells. However assessing the functional efficacy of merozoite specific opsonizing antibodies is challenging due to the short half-life of merozoites and the variability of primary phagocytic cells. Described in detail herein is a method for generating viable merozoites using the E64 protease inhibito...

  3. Plasmodium vivax and Plasmodium falciparum at the crossroads of exchange among islands in Vanuatu: implications for malaria elimination strategies.

    Directory of Open Access Journals (Sweden)

    Chim W Chan

    Full Text Available Understanding the transmission and movement of Plasmodium parasites is crucial for malaria elimination and prevention of resurgence. Located at the limit of malaria transmission in the Pacific, Vanuatu is an ideal candidate for elimination programs due to low endemicity and the isolated nature of its island setting. We analyzed the variation in the merozoite surface protein 1 (msp1 and the circumsporozoite protein (csp of P. falciparum and P. vivax populations to examine the patterns of gene flow and population structures among seven sites on five islands in Vanuatu. Genetic diversity was in general higher in P. vivax than P. falciparum from the same site. In P. vivax, high genetic diversity was likely maintained by greater extent of gene flow among sites and among islands. Consistent with the different patterns of gene flow, the proportion of genetic variance found among islands was substantially higher in P. falciparum (28.81-31.23% than in P. vivax (-0.53-3.99%. Our data suggest that the current island-by-island malaria elimination strategy in Vanuatu, while adequate for P. falciparum elimination, might need to be complemented with more centrally integrated measures to control P. vivax movement across islands.

  4. Plasmodium vivax and Plasmodium falciparum at the crossroads of exchange among islands in Vanuatu: implications for malaria elimination strategies.

    Science.gov (United States)

    Chan, Chim W; Sakihama, Naoko; Tachibana, Shin-Ichiro; Idris, Zulkarnain Md; Lum, J Koji; Tanabe, Kazuyuki; Kaneko, Akira

    2015-01-01

    Understanding the transmission and movement of Plasmodium parasites is crucial for malaria elimination and prevention of resurgence. Located at the limit of malaria transmission in the Pacific, Vanuatu is an ideal candidate for elimination programs due to low endemicity and the isolated nature of its island setting. We analyzed the variation in the merozoite surface protein 1 (msp1) and the circumsporozoite protein (csp) of P. falciparum and P. vivax populations to examine the patterns of gene flow and population structures among seven sites on five islands in Vanuatu. Genetic diversity was in general higher in P. vivax than P. falciparum from the same site. In P. vivax, high genetic diversity was likely maintained by greater extent of gene flow among sites and among islands. Consistent with the different patterns of gene flow, the proportion of genetic variance found among islands was substantially higher in P. falciparum (28.81-31.23%) than in P. vivax (-0.53-3.99%). Our data suggest that the current island-by-island malaria elimination strategy in Vanuatu, while adequate for P. falciparum elimination, might need to be complemented with more centrally integrated measures to control P. vivax movement across islands.

  5. Assessment of Therapeutic Response of Plasmodium vivax and Plasmodium falciparum to Chloroquine in a Malaria Transmission Free Area in Colombia

    Directory of Open Access Journals (Sweden)

    Castillo Carmen Manuela

    2002-01-01

    Full Text Available In order to determine the frequency of therapeutic failures to chloroquine (CQ in patients with malaria due to either Plasmodium falciparum or P. vivax, and to explore the usefulness of a malaria-free city as a sentinel site to monitor the emergence of drug resistance, 53 patients (44 infected with P. vivax and 9 with P. falciparum were evaluated at the Laboratory of Parasitology, Universidad del Valle in Cali, Colombia. Patients received 25 mg/kg of CQ divided in three doses over 48 h; they were followed during 28 days according to WHO/PAHO protocols. While therapeutic failures to CQ in the P. vivax group were not detected, the proportion of therapeutic failures in the P. falciparum group was high (78% and consistent with the reports from endemic areas in Colombia. The diverse origin of cases presenting therapeutic failure confirmed that P. falciparum resistant to CQ is widespread in Colombia, and further supports the change in the national antimalarial drug scheme. Monitoring of drug resistance in malaria free areas would be useful to identify sites requiring efficacy evaluation, and in some situations could be the most appropriate alternative to collect information from endemic areas where therapeutic efficacy studies are not feasible.

  6. Epidemiological and clinical features of Plasmodium falciparum malaria in united nations personnel in Western Bahr el Ghazal State, South Sudan.

    Science.gov (United States)

    He, Dengming; Zhang, Yuqi; Liu, Xiaofeng; Guo, Shimin; Zhao, Donghong; Zhu, Yunjie; Li, Huaidong; Kong, Li

    2013-01-01

    Western Bahr el Ghazal State is located in northwestern South Sudan, which is a tropical area subject to Plasmodium falciparum malaria epidemics. The aim of this study is to explore the epidemiological and clinical features of Plasmodium falciparum malaria in United Nations personnel stationed in this area. From July 2006 to June 2009, epidemiological data and medical records of 678 patients with Plasmodium falciparum malaria at the U.N. level 2 hospital were analyzed. The U.N. personnel were divided into individuals not immune to Plasmodium falciparum and individuals semi-immune to Plasmodium falciparum. The patients were divided into a chemoprophylaxis group (non-immune individuals who complied with the chemoprophylaxis regimen, 582 cases) and a no/incomplete chemoprophylaxis group (non-immune individuals who either did not fully comply with chemoprophylaxis or did not use it at all and semi-immune individuals who did not use chemoprophylaxis, 96 cases). Overall morbidity was about 11.3%. There was a significant difference in the morbidity of semi-immune and non-immune individuals (1.3% vs. 15.1%, PPlasmodium falciparum malaria mainly occurred in rainy season. Gastrointestinal symptoms are an important precursor of malaria. Blood smears and rapid diagnostic tests should be performed after the onset of gastrointestinal symptoms. Appropriate chemoprophylaxis is necessary for reducing the severity of malaria.

  7. 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....

  8. 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...

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

    Science.gov (United States)

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

    1999-02-01

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

  10. [Erythrocyte polymorphism in Mali: epidemiology and resistance mechanisms against severe Plasmodium falciparum malaria].

    Science.gov (United States)

    Doumbo, Ogobara

    2007-01-01

    Homo sapiens and Plasmodium falciparum have co-evolved since the beginning of agriculture, 10,000 to 20,000 years ago. By domesticating plants and animals, humans linked their destiny to one of the main vectors of malaria, Anopheles gambiae sl complex. The biological interaction between these three species led to exchanges of genes and biochemical processes with significant mutual influence. Humans acquired mutations with selective protective advantages against serious and fatal forms of this hemosporidiosis. This is the case of hemoglobin S, hemoglobin C, hemoglobin E, thalassemias, ovalocytosis and G6PD deficiency, among others. Many epidemiological studies published since 1949 have shown a geographic link between malaria and certain erythrocyte polymorphisms. The link with hemoglobin C was discovered only recently, in 2000, initially in Mali in the Dogon population, then in Burkina Faso. Epidemiological and molecular and cellular biology studies done in Mali and elsewhere showed that the C and S alleles, and G6PD deficiency [A-], conferred significant protection against lethal forms of Plasmodium falciparum malaria. Molecular genetic studies, based on functional genomics, transcriptomics and proteomics, provided possible explanations. Advances in molecular biology and a better understanding of the immune mechanisms underlying this protection will hopefully lead to the development of effective second- and third-generation malaria vaccines. Epidemiological and fundamental research efforts have identified some of the mechanisms by which these erythrocyte polymorphisms protect against the most lethal hematozoan parasite, Plasmodium falciparum.

  11. 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...... with levels in children with asymptomatic P. falciparum infections and in healthy children. Concentrations of IL-10 and IL-1Ra were correlated with levels of parasitaemia, but the association of cytokine levels with disease was independent of the association with parasitaemia. Children may tolerate a high...... parasitaemia by neutralizing the parasite-derived toxins. When studying potential anti-toxic molecules we found that children with symptomatic infections had lower concentrations of a phospholipid-binding molecule, beta 2-glycoprotein I (beta 2-GPI), compared with children with asymptomatic infections...

  12. 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.

  13. Increased plasma levels of soluble IL-2R are associated with severe Plasmodium falciparum malaria

    DEFF Research Database (Denmark)

    Jakobsen, P H; Morris-Jones, S; Theander, T G;

    1994-01-01

    Plasma samples from children with mild and severe Plasmodium falciparum malaria and from children with unrelated diseases were collected to investigate whether the clinical outcome of infection was associated with plasma factors which reflected the activity of different cells of the immune system....... Children with severe P. falciparum malaria had significantly higher plasma levels of soluble IL-2R than children with mild malaria. Plasma levels of IL-2R and levels of parasitaemia were significantly correlated. Neither parasitaemia nor plasma levels of tumour necrosis factor-alpha (TNF-alpha), IL-6......, lymphotoxin (LT), interferon-gamma (IFN-gamma), IL-4, soluble IL-4R or soluble CD8 differed significantly between the two groups of children with malaria. High plasma levels of soluble CD8 were associated with failure of lymphocytes to produce IFN-gamma in vitro following stimulation with P. falciparum...

  14. 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...

  15. Evidence of endothelial inflammation, T cell activation, and T cell reallocation in uncomplicated Plasmodium falciparum malaria

    DEFF Research Database (Denmark)

    Elhassan, I M; Hviid, L; Satti, G

    1994-01-01

    To explain the observation that acute Plasmodium falciparum malaria is associated with a transient inability of peripheral blood cells to respond to antigenic stimulation in vitro, we have postulated the disease-induced reallocation of peripheral lymphocytes, possibly by adhesion to inflamed...... endothelium. We measured plasma levels of soluble markers of endothelial inflammation and T cell activation in 32 patients suffering from acute, uncomplication P. falciparum malaria, as well as in 10 healthy, aparasitemic control donors. All donors were residents of a malaria-endemic area of Eastern State...... with the control donors. In addition, we found a disease-induced depletion of T cells with high expression of the LFA-1 antigen, particularly in the CD4+ subset. The results obtained provide further support for the hypothesis of T cell reallocation to inflamed endothelium in acute P. falciparum malaria....

  16. 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

    antibody responses to other parasite isolates are relatively unaffected. However, the detailed kinetics of this VSA antibody acquisition are unknown and hence were the aim of this study. We show that P. falciparum malaria in Ghanaian children generally caused a rapid and sustained increase in variant...... donors (the malaria patient). The data from this first detailed longitudinal study of acquisition of VSA antibodies support the hypothesis that naturally acquired protective immunity to P. falciparum malaria is mediated, at least in part, by VSA-specific antibodies.......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...

  17. 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

    . falciparum malaria was calculated by comparing travelers with clinical malaria (n=52) and non-exposed blood donors (n=119). The index was evaluated on blood donors with suspected malaria exposure (n=249) and compared to the diagnostic performance of IFAT. At a specificity of 95.8 %, the MPA discrimination...... from the MPA exhibits similar diagnostic performance as IFAT for detection of P. falciparum malaria. Combining the antibody response against multiple antigens in a discrimination index increased the sensitivity of the MPA and reduced the readout to a single value....... 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...

  18. 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 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.

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

    Science.gov (United States)

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

    2014-07-25

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

  20. 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.

  1. 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......-erythrocyte membrane protein 1 structural domains. The recombinogenic potential of these 50-mers is not parasite-specific because these sequences also induce recombination when transferred to the yeast Saccharomyces cerevisiae. Genetic cross data suggest that DNA secondary structures (DSS) act as inducers...... 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....

  2. Distinct patterns of cytokine regulation in discrete clinical forms of Plasmodium falciparum malaria

    DEFF Research Database (Denmark)

    Akanmori, B D; Kurtzhals, J A; Goka, B Q;

    2000-01-01

    The pathogenesis of two of the most severe complications of Plasmodium falciparum malaria, cerebral malaria (CM) and severe malarial anaemia (SA) both appear to involve dysregulation of the immune system. We have measured plasma levels of TNF and its two receptors in Ghanaian children with strictly...... defined cerebral malaria (CM), severe malarial anaemia (SA), or uncomplicated malaria (UM) in two independent studies in an area of seasonal, hyperendemic transmission of P. falciparum. Levels of TNF, soluble TNF receptor 1 (sTNF-R1) and 2 (sTNF-R2) were found to be significantly higher in CM than...... in the other clinical categories of P. falciparum malaria patients. Levels of both receptors depended on clinical category, whereas only sTNF-R1 levels were significantly dependent on parasitemia. Detailed analysis of the interrelationship between these variables resolved this pattern further, and identified...

  3. 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...... an automated high-throughput method for this purpose utilizing the pseudoperoxidase activity of intra-erythrocytic haemoglobin. METHODS: Chinese hamster ovary (CHO) cells were grown to confluence in chamber slides and microtiter plates. Cytoadhesion of co-cultured P. falciparum, selected for binding to CHO...... using: i) binding of P. falciparum-infected erythrocytes to CHO cells over-expressing chondroitin sulfate A and ii) CHO cells transfected with CD36. Binding of infected erythrocytes including field isolates to primary endothelial cells was also performed. Data was analysed using linear regression...

  4. Genetically Determined Response to Artemisinin Treatment in Western Kenyan Plasmodium falciparum Parasites

    Science.gov (United States)

    Chebon, Lorna J.; Ngalah, Bidii S.; Ingasia, Luicer A.; Juma, Dennis W.; Muiruri, Peninah; Cheruiyot, Jelagat; Opot, Benjamin; Mbuba, Emmanuel; Imbuga, Mabel; Akala, Hoseah M.; Bulimo, Wallace; Andagalu, Ben; Kamau, Edwin

    2016-01-01

    Genetically determined artemisinin resistance in Plasmodium falciparum has been described in Southeast Asia. The relevance of recently described Kelch 13-propeller mutations for artemisinin resistance in Sub-Saharan Africa parasites is still unknown. Southeast Asia parasites have low genetic diversity compared to Sub-Saharan Africa, where parasites are highly genetically diverse. This study attempted to elucidate whether genetics provides a basis for discovering molecular markers in response to artemisinin drug treatment in P. falciparum in Kenya. The genetic diversity of parasites collected pre- and post- introduction of artemisinin combination therapy (ACT) in western Kenya was determined. A panel of 12 microsatellites and 91 single nucleotide polymorphisms (SNPs) distributed across the P. falciparum genome were genotyped. Parasite clearance rates were obtained for the post-ACT parasites. The 12 microsatellites were highly polymorphic with post-ACT parasites being significantly more diverse compared to pre-ACT (p resistance in Kenya. PMID:27611315

  5. 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.

  6. 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

    2013-04-23

    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.

  7. Risk factors for Plasmodium falciparum and Plasmodium vivax gametocyte carriage in Papua New Guinean children with uncomplicated malaria.

    Science.gov (United States)

    Karl, Stephan; Laman, Moses; Moore, Brioni R; Benjamin, John M; Salib, Mary; Lorry, Lina; Maripal, Samuel; Siba, Peter; Robinson, Leanne J; Mueller, Ivo; Davis, Timothy M E

    2016-08-01

    There are limited data on gametocytaemia risk factors before/after treatment with artemisinin combination therapy in children from areas with transmission of multiple Plasmodium species. We utilised data from a randomised trial comparing artemether-lumefantrine (AL) and artemisinin-naphthoquine (AN) in 230 Papua New Guinean children aged 0.5-5 years with uncomplicated malaria in whom determinants of gametocytaemia by light microscopy were assessed at baseline using logistic regression and during follow-up using multilevel mixed effects modelling. Seventy-four (32%) and 18 (8%) children presented with P. falciparum and P. vivax gametocytaemia, respectively. Baseline P. falciparum gametocytaemia was associated with Hackett spleen grade 1 (odds ratio (95% CI) 4.01 (1.60-10.05) vs grade 0; P<0.001) and haemoglobin (0.95 (0.92-0.97) per 1g/L increase; P<0.001), and P. falciparum asexual parasitaemia in slide-positive cases (0.36 (0.19-0.68) for a 10-fold increase; P=0.002). Baseline P. vivax gametocytaemia was associated with Hackett grade 2 (12.66 (1.31-122.56); P=0.028), mixed P. falciparum/vivax infection (0.16 (0.03-1.00); P=0.050), P. vivax asexual parasitaemia (5.68 (0.98-33.04); P=0.053) and haemoglobin (0.94 (0.88-1.00); P=0.056). For post-treatment P. falciparum gametocytaemia, independent predictors were AN vs AL treatment (4.09 (1.43-11.65)), haemoglobin (0.95 (0.93-0.97)), presence/absence of P. falciparum asexual forms (3.40 (1.66-0.68)) and day post-treatment (0.086 (0.82-0.90)) (P<0.001). Post-treatment P. vivax gametocytaemia was predicted by presence of P. vivax asexual forms (596 (12-28,433); P<0.001). Consistent with slow P. falciparum gametocyte maturation, low haemoglobin, low asexual parasite density and higher spleen grading, markers of increased prior infection exposure/immunity, were strong associates of pre-treatment gametocyte positivity. The persistent inverse association between P. falciparum gametocytaemia and haemoglobin during follow

  8. El Niño and variations in the prevalence of Plasmodium vivax and P. falciparum in Vanuatu.

    Science.gov (United States)

    Gilbert, M; Brindle, R

    2009-12-01

    Malaria, both Plasmodium falciparum and P. vivax, is a major cause of morbidity in Vanuatu. As P. vivax is more prevalent in seasonal climates and P. falciparum in areas of more consistent rainfall, it is postulated that there will be a correlation between the ratio of vivax:falciparum and the El Niño Southern Oscillation (ENSO), which affects sea surface temperatures and rainfall. With changes in global climate, the frequency, duration and strength of the ENSO are expected to alter, influencing the pattern of malaria. The data showed no obvious correlation between ENSO and either cases of malaria or the vivax:falciparum ratio.

  9. Ex vivo susceptibility of Plasmodium falciparum isolates from Dakar, Senegal, to seven standard anti-malarial drugs

    Directory of Open Access Journals (Sweden)

    Pradines Bruno

    2011-10-01

    Full Text Available Abstract Background As a result of widespread chloroquine and sulphadoxine-pyrimethamine resistance, artemisinin-based combination therapy (ACT (which includes artemether-lumefantrine and artesunate-amodiaquine has been recommended as a first-line anti-malarial regimen in Senegal since 2006. Since then, there have been very few reports on the ex vivo susceptibility of Plasmodium falciparum to anti-malarial drugs. To examine whether parasite susceptibility has been affected by the widespread use of ACT, the ex vivo susceptibility of local isolates was assessed at the military hospital of Dakar. Methods The ex vivo susceptibility of 93 P. falciparum isolates from Dakar was successfully determined using the Plasmodium lactate dehydrogenase (pLDH ELISA for the following drugs: chloroquine (CQ, quinine (QN, mefloquine (MQ, monodesethylamodiaquine (MDAQ, lumefantrine (LMF, dihydroartemisinin (DHA and doxycycline (DOX. Results After transformation of the isolate IC50 in ratio of IC50 according to the susceptibility of the 3D7 reference strain (isolate IC50/3D7 IC50, the prevalence of the in vitro resistant isolates with reduced susceptibility was 50% for MQ, 22% for CQ, 12% for DOX, 6% for both QN and MDAQ and 1% for the drugs LMF and DHA. The highest significant positive correlations were shown between responses to CQ and MDAQ (r = 0.569; P r = 0.511; P r = 0.428; P = 0.0001, LMF and MQ (r = 0.413; P = 0.0002, QN and DHA (r = 0.402; P = 0.0003 and QN and MQ (r = 0.421; P = 0.0001. Conclusions The introduction of ACT in 2002 has not induced a decrease in P. falciparum susceptibility to the drugs DHA, MDAQ and LMF, which are common ACT components. However, the prevalence of P. falciparum isolates with reduced susceptibility has increased for both MQ and DOX. Taken together, these data suggest that intensive surveillance of the P. falciparum in vitro susceptibility to anti-malarial drugs in Senegal is required.

  10. Comparative histopathology of mice infected with the 17XL and 17XNL strains of Plasmodium yoelii.

    Science.gov (United States)

    Fu, Yong; Ding, Yan; Zhou, Tao-li; Ou, Qian-yi; Xu, Wen-yue

    2012-04-01

    Plasmodium yoelii 17XL was used to investigate the mechanism of Plasmodium falciparum-caused cerebral malaria, although its histological effect on other mouse organs is still unclear. Here, histological examination was performed on mice infected with P. yoelii 17XL; the effect of P. yoelii 17XL infection on anemia and body weight loss, as well as its lesions in the brain, liver, kidney, lung, and spleen, also was investigated. Plasmodium yoelii 17XL-infected red blood cells were sequestered in the microcirculation of the brain and in the kidney. Compared with the nonlethal P. yoelii 17XNL strain, infection by P. yoelii 17XL caused substantial pulmonary edema, severe anemia, and significant body weight loss. Although P. yoelii 17XNL and 17XL produced a similar focal necrosis in the mouse liver, infection of P. yoelii 17XL induced coalescing of red and white pulp. Mortality caused by P. yoelii 17XL may be due to cerebral malaria, as well as respiratory distress syndrome and severe anemia. Plasmodium yoelii 17XL-infected rodent malaria seems to be a useful model for investigating severe malaria caused by P. falciparum.

  11. Molecular modelling of calcium dependent protein kinase 4 (CDPK4) from Plasmodium falciparum

    CSIR Research Space (South Africa)

    Tsekoa, Tsepo L

    2009-10-01

    Full Text Available Malaria continues to be one of the most serious global health challenges. The increasing incidence of drug resistant Plasmodium strains has emphasised the need for urgent action in the development of new therapeutic strategies against this disease...

  12. Gametocitos de Plasmodium vivax y Plasmodium falciparum: etapas relegadas en el desarrollo de vacunas Plasmodium vivax and Plasmodium falciparum gametocyte stages are neglected in vaccine development

    Directory of Open Access Journals (Sweden)

    Carla Contreras-Ochoa

    2004-02-01

    Full Text Available Los gametocitos de Plasmodium son los responsables de la transmisión del huésped vertebrado al mosquito vector. Sufren un proceso de desarrollo complejo a partir de parásitos asexuales, que no está completamente entendido, expresando proteínas y moléculas de adhesión específicas. Son capaces de inducir una respuesta inmune humoral específica con anticuerpos IgG, y celular específica, con producción de TNFa, IFNg y proliferación de linfocitos gd+, aun cuando existen respuestas inducidas en contra de las etapas previas del parásito (esporozoito, exo-eritrocítica y eritrocítica. Las vacunas destinadas a bloquear la transmisión del parásito no contemplan a los gametocitos circulantes en el huésped como blancos de acción, sino que van enfocadas contra antígenos expresados en los gametos y en las etapas posfertilización. El estudio de los mecanismos que regulan la producción de gametocitos y de la respuesta inmune contra éstos, ofrece una oportunidad para el desarrollo de estrategias adicionales para el control de la transmisión.Plasmodium gametocytes are responsible for transmission from the vertebrate host to the mosquito. Plasmodium gametocytes undergo a complex cycle from asexual stages, through a poorly understood process characterized by expression of stage-specific proteins and adhesion molecules. Gametocytes are capable of inducing specific humoral IgG, and cellular responses, which include induction of TNFa, IFNg and gd+ lymphocyte proliferation, in addition to immune responses to other stages of the parasite (sporozoite, exo-erythrocytic stages, erythrocytic stages. Although transmission-blocking vaccines against Plasmodium do not currently include components against the gametocytes (rather they focus on gametes, zygotes or ookinetes, stages which occur in the mosquito, further understanding of the mechanisms underlying gametocytogenesis and immune responses against these stages may provide additional strategies for

  13. Gametocitos de Plasmodium vivax y Plasmodium falciparum: etapas relegadas en el desarrollo de vacunas Plasmodium vivax and Plasmodium falciparum gametocyte stages are neglected in vaccine development

    OpenAIRE

    Carla Contreras-Ochoa; Ramsey, Janine M.

    2004-01-01

    Los gametocitos de Plasmodium son los responsables de la transmisión del huésped vertebrado al mosquito vector. Sufren un proceso de desarrollo complejo a partir de parásitos asexuales, que no está completamente entendido, expresando proteínas y moléculas de adhesión específicas. Son capaces de inducir una respuesta inmune humoral específica con anticuerpos IgG, y celular específica, con producción de TNFa, IFNg y proliferación de linfocitos gd+, aun cuando existen respuestas inducidas en con...

  14. Antibody responses to a novel Plasmodium falciparum merozoite surface protein vaccine correlate with protection against experimental malaria infection in Aotus monkeys.

    Science.gov (United States)

    Cavanagh, David R; Kocken, Clemens H M; White, John H; Cowan, Graeme J M; Samuel, Kay; Dubbeld, Martin A; Voorberg-van der Wel, Annemarie; Thomas, Alan W; McBride, Jana S; Arnot, David E

    2014-01-01

    The Block 2 region of the merozoite surface protein-1 (MSP-1) of Plasmodium falciparum has been identified as a target of protective immunity by a combination of seroepidemiology and parasite population genetics. Immunogenicity studies in small animals and Aotus monkeys were used to determine the efficacy of recombinant antigens derived from this region of MSP-1 as a potential vaccine antigen. Aotus lemurinus griseimembra monkeys were immunized three times with a recombinant antigen derived from the Block 2 region of MSP-1 of the monkey-adapted challenge strain, FVO of Plasmodium falciparum, using an adjuvant suitable for use in humans. Immunofluorescent antibody assays (IFA) against erythrocytes infected with P. falciparum using sera from the immunized monkeys showed that the MSP-1 Block 2 antigen induced significant antibody responses to whole malaria parasites. MSP-1 Block 2 antigen-specific enzyme-linked immunosorbent assays (ELISA) showed no significant differences in antibody titers between immunized animals. Immunized animals were challenged with the virulent P. falciparum FVO isolate and monitored for 21 days. Two out of four immunized animals were able to control their parasitaemia during the follow-up period, whereas two out of two controls developed fulminating parasitemia. Parasite-specific serum antibody titers measured by IFA were four-fold higher in protected animals than in unprotected animals. In addition, peptide-based epitope mapping of serum antibodies from immunized Aotus showed distinct differences in epitope specificities between protected and unprotected animals.

  15. In vitro antimalarial activity of medicinal plant extracts against Plasmodium falciparum.

    Science.gov (United States)

    Bagavan, Asokan; Rahuman, Abdul Abdul; Kaushik, Naveen Kumar; Sahal, Dinkar

    2011-01-01

    Malaria is a major global public health problem, and the alarming spread of drug resistance and limited number of effective drugs now available underline how important it is to discover new antimalarial compounds. In the present study, ten plants were extracted with ethyl acetate and methanol and tested for their antimalarial activity against chloroquine (CQ)-sensitive (3D7) and CQ-resistant (Dd2 and INDO) strains of Plasmodium falciparum in culture using the fluorescence-based SYBR Green assay. Plant extracts showed moderate to good antiparasitic effects. Promising antiplasmodial activity was found in the extracts from two plants, Phyllanthus emblica leaf 50% inhibitory concentration (IC₅₀) 3D7: 7.25 μg/mL (ethyl acetate extract), 3.125 μg/mL (methanol extract), and Syzygium aromaticum flower bud, IC₅₀ 3D7:13 μg/mL, (ethyl acetate extract) and 6.25 μg/mL (methanol extract). Moderate activity (30-75 μg/mL) was found in the ethyl acetate and methanol extracts of Abrus precatorius (seed) and Gloriosa superba (leaf); leaf ethyl acetate extracts of Annona squamosa and flower of Musa paradisiaca. The above mentioned plant extracts were also found to be active against CQ-resistant strains (Dd2 and INDO). Cytotoxicity study with P. emblica leaf and S. aromaticum flower bud, extracts showed good therapeutic indices. These results demonstrate that leaf ethyl acetate and methanol extracts of P. emblica and flower bud extract of S. aromaticum may serve as antimalarial agents even in their crude form. The isolation of compounds from P. emblica and S. aromaticum seems to be of special interest for further antimalarial studies.

  16. Design, in silico and in vitro evaluation of curcumin analogues against Plasmodium falciparum.

    Science.gov (United States)

    Dohutia, Chandrajit; Chetia, Dipak; Gogoi, Kabita; Sarma, Kishore

    2017-04-01

    The polyphenolic compound curcumin has been reported for its antimalarial properties in various scientific studies. Plasmodium falciparum ATP6, the parasite orthologue of mammalian sarcoplasmic Ca(2+) ATPase (SERCA) has been identified as a key molecular target of both artemisinin and curcumin. The work was thereby undertaken to study the anti-malarial properties of two different series of curcumin analogues based on their docking interactions with PfATP6 and correlating the results with their anti-malarial activity. The compounds were designed retaining similar functional groups as that of the parent curcumin nucleus while incorporating changes in the carbon chain length, unsaturated groups and the number of ketone groups. The compounds (1E, 4E)-1,5-bis(4-methylphenyl)penta-1,4-dien-3-one (CD-9), (1E, 4E)-1,5-bis(4-methoxyphenyl)penta-1,4-dien-3-one (CD-8) and (E)-1,3-bis(4-hydroxylphenyl)prop-2-en-1-one (CD-1) showed IC50 values of 1.642 μM, 1.764 μM and 2.59 μM in 3D7 strain and 3.039 μM, 7.40 μM and 11.3 μM in RKL-2 strain respectively. Detailed structure-activity relationship studies of the compounds showed that CD-9 and CD-8 had a common hydrophobic interaction with the residue Leu268 of the PfATP6 protein and has been postulated through our study to be the reason for their antimalarial activity as seen after corroborating the results with the in vitro study. The study provided valuable insight about the ligand-protein interaction of the various functional groups of curcumin and its analogues against the PfATP6 protein and their importance in imparting antimalarial action.

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

    DEFF Research Database (Denmark)

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

    2007-01-01

    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...... 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 PfEMP...

  18. Susceptibility of Anopheles campestris-like and Anopheles barbirostris species complexes to Plasmodium falciparum and Plasmodium vivax in Thailand.

    Science.gov (United States)

    Thongsahuan, Sorawat; Baimai, Visut; Junkum, Anuluck; Saeung, Atiporn; Min, Gi-Sik; Joshi, Deepak; Park, Mi-Hyun; Somboon, Pradya; Suwonkerd, Wannapa; Tippawangkosol, Pongsri; Jariyapan, Narissara; Choochote, Wej

    2011-02-01

    Nine colonies of five sibling species members of Anopheles barbirostris complexes were experimentally infected with Plasmodium falciparum and Plasmodium vivax. They were then dissected eight and 14 days after feeding for oocyst and sporozoite rates, respectively, and compared with Anopheles cracens. The results revealed that Anopheles campestris-like Forms E (Chiang Mai) and F (Udon Thani) as well as An. barbirostris species A3 and A4 were non-potential vectors for P. falciparum because 0% oocyst rates were obtained, in comparison to the 86.67-100% oocyst rates recovered from An. cracens. Likewise, An. campestris-like Forms E (Sa Kaeo) and F (Ayuttaya), as well as An. barbirostris species A4, were non-potential vectors for P. vivax because 0% sporozoite rates were obtained, in comparison to the 85.71-92.31% sporozoite rates recovered from An. cracens. An. barbirostris species A1, A2 and A3 were low potential vectors for P. vivax because 9.09%, 6.67% and 11.76% sporozoite rates were obtained, respectively, in comparison to the 85.71-92.31% sporozoite rates recovered from An. cracens. An. campestris-like Forms B and E (Chiang Mai) were high-potential vectors for P. vivax because 66.67% and 64.29% sporozoite rates were obtained, respectively, in comparison to 90% sporozoite rates recovered from An. cracens.

  19. Susceptibility of Anopheles campestris-like and Anopheles barbirostris species complexes to Plasmodium falciparum and Plasmodium vivax in Thailand

    Directory of Open Access Journals (Sweden)

    Sorawat Thongsahuan

    2011-02-01

    Full Text Available Nine colonies of five sibling species members of Anopheles barbirostris complexes were experimentally infected with Plasmodium falciparum and Plasmodium vivax. They were then dissected eight and 14 days after feeding for oocyst and sporozoite rates, respectively, and compared with Anopheles cracens. The results revealed that Anopheles campestris-like Forms E (Chiang Mai and F (Udon Thani as well as An. barbirostris species A3 and A4 were non-potential vectors for P. falciparum because 0% oocyst rates were obtained, in comparison to the 86.67-100% oocyst rates recovered from An. cracens. Likewise, An. campestris-like Forms E (Sa Kaeo and F (Ayuttaya, as well as An. barbirostris species A4, were non-potential vectors for P. vivax because 0% sporozoite rates were obtained, in comparison to the 85.71-92.31% sporozoite rates recovered from An. cracens. An. barbirostris species A1, A2 and A3 were low potential vectors for P. vivax because 9.09%, 6.67% and 11.76% sporozoite rates were obtained, respectively, in comparison to the 85.71-92.31% sporozoite rates recovered from An. cracens. An. campestris-like Forms B and E (Chiang Mai were high-potential vectors for P. vivax because 66.67% and 64.29% sporozoite rates were obtained, respectively, in comparison to 90% sporozoite rates recovered from An. cracens.

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

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    Stéphanie Boström

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

  1. Understanding the biology of the Plasmodium falciparum apicoplast; an excellent target for antimalarial drug development.

    Science.gov (United States)

    Chakraborty, Arnish

    2016-08-01

    Malaria is a life-threatening tropical disease, caused by the intracellular parasite Plasmodium falciparum. The World Health Organization counts malaria as one of the top ten causes of worldwide death. The unavailability of a successful malaria vaccine and the ever-increasing instances of drug resistance in the malaria parasite demand the discovery of new targets within P. falciparum for the development of next generation antimalarials. Fortunately, all apicomplexan parasites, including P. falciparum harbor a relict, non-photosynthetic plastid known as the apicoplast. The apicoplast is a semi-autonomous organelle within P. falciparum containing a 35kb circular genome. Despite a genome of its own, majority of the apicoplast proteins are encoded by the parasite nucleus and imported into the apicoplast. The organelle has been shown to be essential to P. falciparum survival and the loss the apicoplast manifests as a 'delayed death' response in the parasite. The apicoplast has evolved out of cyanobacteria in a complex, two step endosymbiotic event. As a result the architecture and the gene expression machinery of the apicoplast is quite bacteria-like and is susceptible to a wide range of antibiotics such as fosmidomycin, tetracycline, azithromycin, clindamycin and triclosan. The biosynthetic pathways for isoprenoids, fatty acids and heme operate within the malaria apicoplast, making the organelle an excellent target for drug development. The review focuses on the evolution, biology and the essentiality of the apicoplast within the malaria parasite and discusses some of the recent achievements towards the design and discovery of apicoplast targeted antimalarial compounds.

  2. Mitochondrial DNA from the eradicated European Plasmodium vivax and P. falciparum from 70-year-old slides from the Ebro Delta in Spain

    Science.gov (United States)

    Gelabert, Pere; Sandoval-Velasco, Marcela; Olalde, Iñigo; Fregel, Rosa; Rieux, Adrien; Escosa, Raül; Aranda, Carles; Paaijmans, Krijn; Mueller, Ivo; Gilbert, M. Thomas P.; Lalueza-Fox, Carles

    2016-01-01

    Phylogenetic analysis of Plasmodium parasites has indicated that their modern-day distribution is a result of a series of human-mediated dispersals involving transport between Africa, Europe, America, and Asia. A major outstanding question is the phylogenetic affinity of the malaria causing parasites Plasmodium vivax and falciparum in historic southern Europe—where it was endemic until the mid-20th century, after which it was eradicated across the region. Resolving the identity of these parasites will be critical for answering several hypotheses on the malaria dispersal. Recently, a set of slides with blood stains of malaria-affected people from the Ebro Delta (Spain), dated between 1942 and 1944, have been found in a local medical collection. We extracted DNA from three slides, two of them stained with Giemsa (on which Plasmodium parasites could still be seen under the microscope) and another one consisting of dried blood spots. We generated the data using Illumina sequencing after using several strategies aimed at increasing the Plasmodium DNA yield: depletion of the human genomic (g)DNA content through hybridization with human gDNA baits, and capture-enrichment using gDNA derived from P. falciparum. Plasmodium mitochondrial genome sequences were subsequently reconstructed from the resulting data. Phylogenetic analysis of the eradicated European P. vivax mtDNA genome indicates that the European isolate is closely related to the most common present-day American haplotype and likely entered the American continent post-Columbian contact. Furthermore, the European P. falciparum mtDNA indicates a link with current Indian strains that is in agreement with historical accounts. PMID:27671660

  3. Effects of the vascular endothelial growth factor receptor-2 (VEGFR-2) inhibitor SU5416 on in vitro cultures of Plasmodium falciparum

    DEFF Research Database (Denmark)

    Hempel, Casper; Hoyer, Nils; Staalsø, Trine

    2014-01-01

    BACKGROUND: Vascular endothelial growth factor (VEGF) is taken up by parasitized red blood cells during malaria and stimulates intra-erythrocytic growth of Plasmodium falciparum in vitro. The cause and consequence of this uptake is not understood. METHODS: Plasmodium falciparum was cultured in vi...

  4. Quinine dimers are potent inhibitors of the Plasmodium falciparum chloroquine resistance transporter and are active against quinoline-resistant P. falciparum.

    Science.gov (United States)

    Hrycyna, Christine A; Summers, Robert L; Lehane, Adele M; Pires, Marcos M; Namanja, Hilda; Bohn, Kelsey; Kuriakose, Jerrin; Ferdig, Michael; Henrich, Philipp P; Fidock, David A; Kirk, Kiaran; Chmielewski, Jean; Martin, Rowena E

    2014-03-21

    Chloroquine (CQ) resistance in the human malaria parasite Plasmodium falciparum is primarily conferred by mutations in the "chloroquine resistance transporter" (PfCRT). The resistance-conferring form of PfCRT (PfCRT(CQR)) mediates CQ resistance by effluxing the drug from the parasite's digestive vacuole, the acidic compartment in which CQ exerts its antiplasmodial effect. PfCRT(CQR) can also decrease the parasite's susceptibility to other quinoline drugs, including the current antimalarials quinine and amodiaquine. Here we describe interactions between PfCRT(CQR) and a series of dimeric quinine molecules using a Xenopus laevis oocyte system for the heterologous expression of PfCRT and using an assay that detects the drug-associated efflux of H(+) ions from the digestive vacuole in parasites that harbor different forms of PfCRT. The antiplasmodial activities of dimers 1 and 6 were also examined in vitro (against drug-sensitive and drug-resistant strains of P. falciparum) and in vivo (against drug-sensitive P. berghei). Our data reveal that the quinine dimers are the most potent inhibitors of PfCRT(CQR) reported to date. Furthermore, the lead compounds (1 and 6) were not effluxed by PfCRT(CQR) from the digestive vacuole but instead accumulated to very high levels within this organelle. Both 1 and 6 exhibited in vitro antiplasmodial activities that were inversely correlated with CQ. Moreover, the additional parasiticidal effect exerted by 1 and 6 in the drug-resistant parasites was attributable, at least in part, to their ability to inhibit PfCRT(CQR). This highlights the potential for devising new antimalarial therapies that exploit inherent weaknesses in a key resistance mechanism of P. falciparum.

  5. Mitochondrial genes support a common origin of rodent malaria parasites and Plasmodium falciparum's relatives infecting great apes

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    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

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

    Science.gov (United States)

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

    2017-01-01

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

  7. [Is Plasmodium falciparum, the parasite responsible for tropical malaria, resistant to fansidar?].

    Science.gov (United States)

    Holzer, B; Keller, H; Frossard, E; Stürchler, D

    1980-03-01

    A world-wide increase of malaria infections is observed. Malaria is imported into Switzerland mainly by tourists and recently by refugees from South East Asia. The strains of P. falciparum resistant to treatment are of increasing importance. A patient with P. falciparum infection from Cambodia is reported, who suffered from three episodes of malaria recrudescence within ten weeks, in spite of adequate therapy with quinine and Fansidar. The definition, the significance and the geographical distribution of resistances and the possible cause for a P. falciparum recrudescence are discussed. For the treatment of repeating recrudescence quinine and Fansidar are recommended, followed by a suppressive Fansidar prophylaxy for 4--8 weeks.

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

    OpenAIRE

    Garver, Lindsey S.; Yuemei Dong; George Dimopoulos

    2009-01-01

    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 depl...

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

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    Alvarez Eugenia

    2005-06-01

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

  10. Evaluation of a rapid whole blood immunochromatographic assay for the diagnosis of Plasmodium falciparum and Plasmodium vivax malaria.

    Science.gov (United States)

    Fernando, S D; Karunaweera, N D; Fernando, W P

    2004-03-01

    Microscopic examination of blood smears is the 'gold standard' for malaria diagnosis, but is labour intensive and requires skilled operators. Plasmodium vivax malaria accounts for up to 70% of infections in Sri Lanka. The objective of this study was to determine the effectiveness of an immunochromatographic test which can detect both the species of Plasmodium, P. vivax and P. falciparum, present in Sri Lanka. Prospective study from May 2001 to March 2002. All persons above 5 years of age who presented to the Malaria Research Station, Kataragama or the Anti-malaria Clinic, Kurunegala, with a history of fever were recruited to the study. Thick and thin blood smears were examined for malarial parasites. The rapid diagnostic test (RDT), ICT Malaria P.f/P.v (AMRAD ICT, Australia) was performed simultaneously by an independent investigator. The severity of clinical disease of all patients was evaluated. The study sample comprised 328 individuals of whom 126 (38%) were infected, 102 with P. vivax (31.1%) and 24 with P. falciparum (7.3%). The RDT was found to be highly sensitive (100%) and specific (100%) for the diagnosis of P. falciparum when compared with field microscopy. The sensitivity for the diagnosis of P. vivax malaria was only 70%. When P. vivax parasitaemia was greater than 5000 parasites/microL the RDT was 96.2% sensitive. A significant association was noted between the band intensity on the dipstick and both peripheral blood parasitaemia (p ICT Malaria P.f/P.v test can be used in Sri Lanka in the absence of microscopists.

  11. Sero-epidemiological evaluation of changes in Plasmodium falciparum and Plasmodium vivax transmission patterns over the rainy season in Cambodia

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    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

  12. A Method for Amplicon Deep Sequencing of Drug Resistance Genes in Plasmodium falciparum Clinical Isolates from India.

    Science.gov (United States)

    Rao, Pavitra N; Uplekar, Swapna; Kayal, Sriti; Mallick, Prashant K; Bandyopadhyay, Nabamita; Kale, Sonal; Singh, Om P; Mohanty, Akshaya; Mohanty, Sanjib; Wassmer, Samuel C; Carlton, Jane M

    2016-06-01

    A major challenge to global malaria control and elimination is early detection and containment of emerging drug resistance. Next-generation sequencing (NGS) methods provide the resolution, scalability, and sensitivity required for high-throughput surveillance of molecular markers of drug resistance. We have developed an amplicon sequencing method on the Ion Torrent PGM platform for targeted resequencing of a panel of six Plasmodium falciparum genes implicated in resistance to first-line antimalarial therapy, including artemisinin combination therapy, chloroquine, and sulfadoxine-pyrimethamine. The protocol was optimized using 12 geographically diverse P. falciparum reference strains and successfully applied to multiplexed sequencing of 16 clinical isolates from India. The sequencing results from the reference strains showed 100% concordance with previously reported drug resistance-associated mutations. Single-nucleotide polymorphisms (SNPs) in clinical isolates revealed a number of known resistance-associated mutations and other nonsynonymous mutations that have not been implicated in drug resistance. SNP positions containing multiple allelic variants were used to identify three clinical samples containing mixed genotypes indicative of multiclonal infections. The amplicon sequencing protocol has been designed for the benchtop Ion Torrent PGM platform and can be operated with minimal bioinformatics infrastructure, making it ideal for use in countries that are endemic for the disease to facilitate routine large-scale surveillance of the emergence of drug resistance and to ensure continued success of the malaria treatment policy.

  13. Plasmodium falciparum Protein Microarray Antibody Profiles Correlate With Protection From Symptomatic Malaria in Kenya.

    Science.gov (United States)

    Dent, Arlene E; Nakajima, Rie; Liang, Li; Baum, Elisabeth; Moormann, Ann M; Sumba, Peter Odada; Vulule, John; Babineau, Denise; Randall, Arlo; Davies, D Huw; Felgner, Philip L; Kazura, James W

    2015-11-01

    Immunoglobulin G antibodies (Abs) to Plasmodium falciparum antigens have been associated with naturally acquired immunity to symptomatic malaria. We probed protein microarrays covering 824 unique P. falciparum protein features with plasma from residents of a community in Kenya monitored for 12 weeks for (re)infection and symptomatic malaria after administration of antimalarial drugs. P. falciparum proteins recognized by Abs from 88 children (aged 1-14 years) and 86 adults (aged ≥ 18 years), measured at the beginning of the observation period, were ranked by Ab signal intensity. Abs from immune adults reacted with a total 163 of 824 P. falciparum proteins. Children gradually acquired Abs to the full repertoire of antigens recognized by adults. Abs to some antigens showed high seroconversion rates, reaching maximal levels early in childhood, whereas others did not reach adult levels until adolescence. No correlation between Ab signal intensity and time to (re)infection was observed. In contrast, Ab levels to 106 antigens were significantly higher in children who were protected from symptomatic malaria compared with those who were not. Abs to antigens predictive of protection included P. falciparum erythrocyte membrane protein 1, merozoite surface protein (MSP) 10, MSP2, liver-stage antigen 3, PF70, MSP7, and Plasmodium helical interspersed subtelomeric domain protein. Protein microarrays may be useful in the search for malaria antigens associated with protective immunity. © The Author 2015. 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.

  14. A systematic classification of Plasmodium falciparum P-loop NTPases: structural and functional correlation

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    Chauhan Virander S

    2009-04-01

    Full Text Available Abstract Background The P-loop NTPases constitute one of the largest groups of globular protein domains that play highly diverse functional roles in most of the organisms. Even with the availability of nearly 300 different Hidden Markov Models representing the P-loop NTPase superfamily, not many P-loop NTPases are known in Plasmodium falciparum. A number of characteristic attributes of the genome have resulted into the lack of knowledge about this functionally diverse, but important class of proteins. Method In the study, protein sequences with characteristic motifs of NTPase domain (Walker A and Walker B are computationally extracted from the P. falciparum database. A detailed secondary structure analysis, functional classification, phylogenetic and orthology studies of the NTPase domain of repertoire of 97 P. falciparum P-loop NTPases is carried out. Results Based upon distinct sequence features and secondary structure profile of the P-loop domain of obtained sequences, a cladistic classification is also conceded: nucleotide kinases and GTPases, ABC and SMC family, SF1/2 helicases, AAA+ and AAA protein families. Attempts are made to identify any ortholog(s for each of these proteins in other Plasmodium sp. as well as its vertebrate host, Homo sapiens. A number of P. falciparum P-loop NTPases that have no homologue in the host, as well as those annotated as hypothetical proteins and lack any characteristic functional domain are identified. Conclusion The study suggests a strong correlation between sequence and secondary structure profile of P-loop domains and functional roles of these proteins and thus provides an opportunity to speculate the role of many hypothetical proteins. The study provides a methodical framework for the characterization of biologically diverse NTPases in the P. falciparum genome. The efforts made in the analysis are first of its kind; and the results augment to explore the functional role of many of these proteins from

  15. An impossible journey? The development of Plasmodium falciparum NF54 in Culex quinquefasciatus.

    Science.gov (United States)

    Knöckel, Julia; Molina-Cruz, Alvaro; Fischer, Elizabeth; Muratova, Olga; Haile, Ashley; Barillas-Mury, Carolina; Miller, Louis H

    2013-01-01

    Although Anopheles mosquitoes are the vectors for human Plasmodium spp., there are also other mosquito species-among them culicines (Culex spp., Aedes spp.)-present in malaria-endemic areas. Culicine mosquitoes transmit arboviruses and filarial worms to humans and are vectors for avian Plasmodium spp., but have never been observed to transmit human Plasmodium spp. When ingested by a culicine mosquito, parasites could either face an environment that does not allow development due to biologic incompatibility or be actively killed by the mosquito's immune system. In the latter case, the molecular mechanism of killing must be sufficiently powerful that Plasmodium is not able to overcome it. To investigate how human malaria parasites develop in culicine mosquitoes, we infected Culex quinquefasciatus with Plasmodium falciparum NF54 and monitored development of parasites in the blood bolus and midgut epithelium at different time points. Our results reveal that ookinetes develop in the midgut lumen of C. quinquefasciatus in slightly lower numbers than in Anopheles gambiae G3. After 30 hours, parasites have invaded the midgut and can be observed on the basal side of the midgut epithelium by confocal and transmission electron microscopy. Very few of the parasites in C. quinquefasciatus are alive, most of them are lysed. Eight days after the mosquito's blood meal, no oocysts can be found in C. quinquefasciatus. Our results suggest that the mosquito immune system could be involved in parasite killing early in development after ookinetes have crossed the midgut epithelium and come in contact with the mosquito hemolymph.

  16. Biochemical and structural characterization of the apicoplast dihydrolipoamide dehydrogenase of Plasmodium falciparum.

    Science.gov (United States)

    Laine, Larissa M; Biddau, Marco; Byron, Olwyn; Müller, Sylke

    2015-01-14

    PDC (pyruvate dehydrogenase complex) is a multi-enzyme complex comprising an E1 (pyruvate decarboxylase), an E2 (dihydrolipomide acetyltransferase) and an E3 (dihydrolipoamide dehydrogenase). PDC catalyses the decarboxylation of pyruvate and forms acetyl-CoA and NADH. In the human malaria parasite Plasmodium falciparum, the single PDC is located exclusively in the apicoplast. Plasmodium PDC is essential for parasite survival in the mosquito vector and for late liver stage development in the human host, suggesting its suitability as a target for intervention strategies against malaria. Here, PfaE3 (P. falciparum apicoplast E3) was recombinantly expressed and characterized. Biochemical parameters were comparable with those determined for E3 from other organisms. A homology model for PfaE3 reveals an extra anti-parallel β-strand at the position where human E3BP (E3-binding protein) interacts with E3; a parasite-specific feature that may be exploitable for drug discovery against PDC. To assess the biological role of Pfae3, it was deleted from P. falciparum and although the mutants are viable, they displayed a highly synchronous growth phenotype during intra-erythrocytic development. The mutants also showed changes in the expression of some mitochondrial and antioxidant proteins suggesting that deletion of Pfae3 impacts on the parasite's metabolic function with downstream effects on the parasite's redox homoeostasis and cell cycle.

  17. 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.

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

    Directory of Open Access Journals (Sweden)

    Zborowski Maciej

    2008-04-01

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

  19. Susceptibility of Anopheles gambiae and Anopheles stephensi to tropical isolates of Plasmodium falciparum

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    Ranford-Cartwright Lisa C

    2007-10-01

    Full Text Available Abstract Background The susceptibility of anopheline mosquito species to Plasmodium infection is known to be variable with some mosquitoes more permissive to infection than others. Little work, however, has been carried out investigating the susceptibility of major malaria vectors to geographically diverse tropical isolates of Plasmodium falciparum aside from examining the possibility of infection extending its range from tropical regions into more temperate zones. Methods This study investigates the susceptibility of two major tropical mosquito hosts (Anopheles gambiae and Anopheles stephensi to P. falciparum isolates of different tropical geographical origins. Cultured parasite isolates were fed via membrane feeders simultaneously to both mosquito species and the resulting mosquito infections were compared. Results Infection prevalence was variable with African parasites equally successful in both mosquito species, Thai parasites significantly more successful in An. stephensi, and PNG parasites largely unsuccessful in both species. Conclusion Infection success of P. falciparum was variable according to geographical origin of both the parasite and the mosquito. Data presented raise the possibility that local adaptation of tropical parasites and mosquitoes has a role to play in limiting gene flow between allopatric parasite populations.

  20. 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

  1. A novel flow cytometric hemozoin detection assay for real-time sensitivity testing of Plasmodium falciparum.

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    Maria Rebelo

    Full Text Available Resistance of Plasmodium falciparum to almost all antimalarial drugs, including the first-line treatment with artemisinins, has been described, representing an obvious threat to malaria control. In vitro antimalarial sensitivity testing is crucial to detect and monitor drug resistance. Current assays have been successfully used to detect drug effects on parasites. However, they have some limitations, such as the use of radioactive or expensive reagents or long incubation times. Here we describe a novel assay to detect antimalarial drug effects, based on flow cytometric detection of hemozoin (Hz, which is rapid and does not require any additional reagents. Hz is an optimal parasite maturation indicator since its amount increases as the parasite matures. Due to its physical property of birefringence, Hz depolarizes light, hence it can be detected using optical methods such as flow cytometry. A common flow cytometer was adapted to detect light depolarization caused by Hz. Synchronized in vitro cultures of P. falciparum were incubated for 48 hours with several antimalarial drugs. Analysis of depolarizing events, corresponding to parasitized red blood cells containing Hz, allowed the detection of parasite maturation. Moreover, chloroquine resistance and the inhibitory effect of all antimalarial drugs tested, except for pyrimethamine, could be determined as early as 18 to 24 hours of incubation. At 24 hours incubation, 50% inhibitory concentrations (IC50 were comparable to previously reported values. These results indicate that the reagent-free, real-time Hz detection assay could become a novel assay for the detection of drug effects on Plasmodium falciparum.

  2. Role of plasmepsin V in export of diverse protein families from the Plasmodium falciparum exportome.

    Science.gov (United States)

    Boddey, Justin A; Carvalho, Teresa G; Hodder, Anthony N; Sargeant, Tobias J; Sleebs, Brad E; Marapana, Danushka; Lopaticki, Sash; Nebl, Thomas; Cowman, Alan F

    2013-05-01

    Plasmodium falciparum exports several hundred effector proteins that remodel the host erythrocyte and enable parasites to acquire nutrients, sequester in the circulation and evade immune responses. The majority of exported proteins contain the Plasmodium export element (PEXEL; RxLxE/Q/D) in their N-terminus, which is proteolytically cleaved in the parasite endoplasmic reticulum by Plasmepsin V, and is necessary for export. Several exported proteins lack a PEXEL or contain noncanonical motifs. Here, we assessed whether Plasmepsin V could process the N-termini of diverse protein families in P. falciparum. We show that Plasmepsin V cleaves N-terminal sequences from RIFIN, STEVOR and RESA multigene families, the latter of which contain a relaxed PEXEL (RxLxxE). However, Plasmepsin V does not cleave the N-terminal sequence of the major exported virulence factor erythrocyte membrane protein 1 (PfEMP1) or the PEXEL-negative exported proteins SBP-1 or REX-2. We probed the substrate specificity of Plasmepsin V and determined that lysine at the PEXEL P3 position, which is present in PfEMP1 and other putatively exported proteins, blocks Plasmepsin V activity. Furthermore, isoleucine at position P1 also blocked Plasmepsin V activity. The specificity of Plasmepsin V is therefore exquisitely confined and we have used this novel information to redefine the predicted P. falciparum PEXEL exportome.

  3. Plasmodium falciparum Adhesins Play an Essential Role in Signalling and Activation of Invasion into Human Erythrocytes.

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    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.

  4. Effect of Farnesyltransferase Inhibitor R115777 on Mitochondria of Plasmodium falciparum.

    Science.gov (United States)

    Ha, Young Ran; Hwang, Bae-Geun; Hong, Yeonchul; Yang, Hye-Won; Lee, Sang Joon

    2015-08-01

    The parasite Plasmodium falciparum causes severe malaria and is the most dangerous to humans. However, it exhibits resistance to their drugs. Farnesyltransferase has been identified in pathogenic protozoa of the genera Plasmodium and the target of farnesyltransferase includes Ras family. Therefore, the inhibition of farnesyltransferase has been suggested as a new strategy for the treatment of malaria. However, the exact functional mechanism of this agent is still unknown. In addition, the effect of farnesyltransferase inhibitor (FTIs) on mitochondrial level of malaria parasites is not fully understood. In this study, therefore, the effect of a FTI R115777 on the function of mitochondria of P. falciparum was investigated experimentally. As a result, FTI R115777 was found to suppress the infection rate of malaria parasites under in vitro condition. It also reduces the copy number of mtDNA-encoded cytochrome c oxidase III. In addition, the mitochondrial membrane potential (ΔΨm) and the green fluorescence intensity of MitoTracker were decreased by FTI R115777. Chloroquine and atovaquone were measured by the mtDNA copy number as mitochondrial non-specific or specific inhibitor, respectively. Chloroquine did not affect the copy number of mtDNA-encoded cytochrome c oxidase III, while atovaquone induced to change the mtDNA copy number. These results suggest that FTI R115777 has strong influence on the mitochondrial function of P. falciparum. It may have therapeutic potential for malaria by targeting the mitochondria of parasites.

  5. An FtsH protease is recruited to the mitochondrion of Plasmodium falciparum.

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    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.

  6. Malaria risk factor assessment using active and passive surveillance data from Aceh Besar, Indonesia, a low endemic, malaria elimination setting with Plasmodium knowlesi, Plasmodium vivax, and Plasmodium falciparum.

    Science.gov (United States)

    Herdiana, Herdiana; Cotter, Chris; Coutrier, Farah N; Zarlinda, Iska; Zelman, Brittany W; Tirta, Yusrifar Kharisma; Greenhouse, Bryan; Gosling, Roly D; Baker, Peter; Whittaker, Maxine; Hsiang, Michelle S

    2016-09-13

    As malaria transmission declines, it becomes more geographically focused and more likely due to asymptomatic and non-falciparum infections. To inform malaria elimination planning in the context of this changing epidemiology, local assessments on the risk factors for malaria infection are necessary, yet challenging due to the low number of malaria cases. A population-based, cross-sectional study was performed using passive and active surveillance data collected in Aceh Besar District, Indonesia from 2014 to 2015. Malaria infection was defined as symptomatic polymerase chain reaction (PCR)-confirmed infection in index cases reported from health facilities, and asymptomatic or symptomatic PCR-confirmed infection identified in reactive case detection (RACD). Potential risk factors for any infection, species-specific infection, or secondary-case detection in RACD were assessed through questionnaires and evaluated for associations. Nineteen Plasmodium knowlesi, 12 Plasmodium vivax and six Plasmodium falciparum cases were identified passively, and 1495 community members screened in RACD, of which six secondary cases were detected (one P. knowlesi, three P. vivax, and two P. falciparum, with four being asymptomatic). Compared to non-infected subjects screened in RACD, cases identified through passive or active surveillance were more likely to be male (AOR 12.5, 95 % CI 3.0-52.1), adult (AOR 14.0, 95 % CI 2.2-89.6 for age 16-45 years compared to malaria infection in index and RACD identified cases was associated with forest exposure, particularly overnights in the forest for work. In low-transmission settings, utilization of data available through routine passive and active surveillance can support efforts to target individuals at high risk.

  7. Malarial parasite diversity in chimpanzees: the value of comparative approaches to ascertain the evolution of Plasmodium falciparum antigens.

    Science.gov (United States)

    Pacheco, M Andreína; Cranfield, Michael; Cameron, Kenneth; Escalante, Ananias A

    2013-09-17

    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. 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. 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. Msp2 and var2CSA, however, show extended

  8. 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

  9. DNA repair mechanisms and their biological roles in the malaria parasite Plasmodium falciparum.

    Science.gov (United States)

    Lee, Andrew H; Symington, Lorraine S; Fidock, David A

    2014-09-01

    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.

  10. Plasmodium falciparum MAEBL is a unique member of the ebl family.

    Science.gov (United States)

    Blair, Peter L; Kappe, Stefan H I; Maciel, Jorge E; Balu, Bharath; Adams, John H

    2002-06-01

    Malaria is one of the deadliest human diseases and efforts to control it have been difficult due to the protozoan parasites' complex biology. Malaria merozoite invasion of erythrocytes is an essential part of blood-stage infections. The invasion process is mediated by numerous parasite molecules, such as EBA-175, a member of the ebl family of erythrocyte binding proteins. We have identified maebl, an ebl paralogue, in Plasmodium falciparum and found it highly conserved with its orthologues in P. yoelii and P. berghei, but distinct from other Plasmodium ebl. Importantly, the putative MAEBL ligand domains are highly conserved and are similar to AMA-1, but not the consensus DBL ligand domains present in all other ebl. In mature merozoites, MAEBL localized with rhoptry proteins (RhopH2, RAP-1), including surface localization with RhopH2, but not microneme proteins (EBA-175, BAEBL). MAEBL appears as proteolytically processed fragments in P. falciparum parasites. The amino cysteine-rich ligand domains were present primarily in culture supernatants, while the carboxyl cysteine-rich domain adjacent to the transmembrane domain was preferentially isolated from Triton X-100 extracted fractions. These data indicate that the primary structure of maebl is highly conserved among Plasmodium species, while its characteristics demonstrate a function unique among the ebl proteins.

  11. Plasmodium falciparum-infected erythrocyte knob density is linked to the PfEMP1 variant expressed

    DEFF Research Database (Denmark)

    Subramani, Ramesh; Quadt, Katharina; Jeppesen, Anine Engholm

    2015-01-01

    regardless of the PfEMP1 expressed. Our study documents for the first time that knob density is related to the PfEMP1 variant expressed. This may reflect topological requirements to ensure optimal adhesive properties of the IEs. IMPORTANCE: Infections with Plasmodium falciparum malaria parasites are still...... responsible for many deaths, especially among children and pregnant women. New interventions are needed to reduce severe illness and deaths caused by this malaria parasite. Thus, a better understanding of the mechanisms behind the pathogenesis is essential. A main reason why Plasmodium falciparum malaria......UNLABELLED: Members of the clonally variant Plasmodium falciparum erythrocyte membrane protein 1 (PfEMP1) family mediate adhesion of infected erythrocytes (IEs) to vascular receptors. PfEMP1 expression is normally confined to nanoscale knob protrusions on the IE surface membrane. To investigate...

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

    DEFF Research Database (Denmark)

    Subramani, Ramesh; Quadt, Katharina; Jeppesen, Anine Engholm;

    2015-01-01

    UNLABELLED: Members of the clonally variant Plasmodium falciparum erythrocyte membrane protein 1 (PfEMP1) family mediate adhesion of infected erythrocytes (IEs) to vascular receptors. PfEMP1 expression is normally confined to nanoscale knob protrusions on the IE surface membrane. To investigate...... regardless of the PfEMP1 expressed. Our study documents for the first time that knob density is related to the PfEMP1 variant expressed. This may reflect topological requirements to ensure optimal adhesive properties of the IEs. IMPORTANCE: Infections with Plasmodium falciparum malaria parasites are still...... responsible for many deaths, especially among children and pregnant women. New interventions are needed to reduce severe illness and deaths caused by this malaria parasite. Thus, a better understanding of the mechanisms behind the pathogenesis is essential. A main reason why Plasmodium falciparum malaria...

  13. Determination of PCT on admission is a useful tool for the assessment of disease severity in travelers with imported Plasmodium falciparum malaria.

    Science.gov (United States)

    Righi, Elda; Merelli, Maria; Arzese, Alessandra; Siega, Paola Della; Scarparo, Claudio; Bassetti, Matteo

    2016-03-01

    Procalcitonin (PCT) and C-reactive protein (CRP) may be useful to predict complicated forms of malaria. A total of 30 consecutive travelers diagnosed with Plasmodium falciparum malaria over a two-year period were included in the study. Patients with complicated Plasmodium falciparum malaria showed higher levels of parasitemia (P = 0.0001), PCT (P = 0.0018), CRP (P = 0.0005), bilirubinemia (P = 0.004), and a lower platelet count (PPlasmodium falciparum malaria.

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

    Science.gov (United States)

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

    2013-02-01

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

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

    Science.gov (United States)

    Kone, Aminatou; van de Vegte-Bolmer, Marga; Siebelink-Stoter, Rianne; van Gemert, Geert-Jan; Dara, Antoine; Niangaly, Hamidou; Luty, Adrian; Doumbo, Ogobara K; Sauerwein, Robert; Djimde, Abdoulaye A

    2010-08-15

    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 SP treated individuals. However, using a direct feeding assay in Mali, we showed that gametocytes present in peripheral venous blood post-SP treatment had reduced infectivity for Anopheles gambiae sensu stricto (ss) mosquitoes. We investigated the potential mechanisms involved in the dhfr and dhps quintuple mutant NF-135 and the single dhps 437 mutant NF-54. Concentrations of sulfadoxine (S) and pyrimethamine (P) equivalent to the serum levels of the respective drugs on day 3 (S=61 microg/ml, P=154.7 ng/ml) day 7 (S=33.8 microg/ml, P=66.6 ng/ml) and day 14 (S=14.2 microg/ml, P=15.7 ng/ml) post-SP treatment were used to study the effect on gametocytogenesis, gametocyte maturation and infectivity to Anopheles stephensi mosquitoes fed through an artificial membrane. The drugs readily induced gametocytogenesis in the mutant NF-135 strain but effectively killed the wild-type NF-54. However, both drugs impaired gametocyte maturation yielding odd-shaped non-exflagellating mature gametocytes. The concomitant ingestion of both S and P together with gametocytemic blood-meal significantly reduced the prevalence of oocyst positivity as well as oocyst density when compared to controls (Pmosquito survival by up to 65% (Pmosquito survival. Copyright 2010. Published by Elsevier Ltd.

  16. In vitro antiplasmodial activity of Clathria vulpina sponge associated bacteria against Plasmodium falciparum

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    Samuel Jacob Inbaneson

    2012-08-01

    Full Text Available Objective: To identify the possible antiplasmodial drugs from bacteria associated with marine sponge Clathria vulpina (C. vulpina. Methods: The C. vulpina samples were collected from Thondi coast and subjected to enumeration and isolation of associated bacteria. Filtered and sterilized extracts (100, 50, 25, 12.5, 6.25 and 3.125 毺 g/mL from bacterial isolates were screened for antiplasmodial activity against Plasmodium falciparum. Potential extracts were also screened for biochemical constituents. Results: Thirty one bacterial isolates were isolated from twelve sponge samples collected from Thondi coast and screened for antiplasmodial assay. The count of bacterial strains were maximum in November 2007 (19暳 104 CFU/g and the average count was maximum during the monsoon season (110暳 103 CFU/g. The antiplasmodial activity of isolate THB15 was highly comparable (IC50 = 20.73 毺 g/mL with the positive control chloroquine (IC50 = 19.59 毺 g/mL and 21 bacterial isolates showed IC 50 value of more than 100 毺 g/mL. Statistical analysis reveals that, significant in vitro antiplasmodial activity (P<0.05 was observed between the concentrations and time of exposure. The chemical injury to erythrocytes showed no morphological changes in erythrocytes by the ethyl acetate extract of bacterial isolates after 48 h of incubation. The in vitro antiplasmodial activity might be due to the presence of sugars and alkaloids in the ethyl acetate extracts of bacterial isolates. Conclusions: The ethyl acetate extract of THB15 possesses lead compounds for the development of antiplasmodial drugs.

  17. Quantitative trait loci mapping reveals candidate pathways regulating cell cycle duration in Plasmodium falciparum

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    Siwo Geoffrey

    2010-10-01

    Full Text Available Abstract Background Elevated parasite biomass in the human red blood cells can lead to increased malaria morbidity. The genes and mechanisms regulating growth and development of Plasmodium falciparum through its erythrocytic cycle are not well understood. We previously showed that strains HB3 and Dd2 diverge in their proliferation rates, and here use quantitative trait loci mapping in 34 progeny from a cross between these parent clones along with integrative bioinformatics to identify genetic loci and candidate genes that control divergences in cell cycle duration. Results Genetic mapping of cell cycle duration revealed a four-locus genetic model, including a major genetic effect on chromosome 12, which accounts for 75% of the inherited phenotype variation. These QTL span 165 genes, the majority of which have no predicted function based on homology. We present a method to systematically prioritize candidate genes using the extensive sequence and transcriptional information available for the parent lines. Putative functions were assigned to the prioritized genes based on protein interaction networks and expression eQTL from our earlier study. DNA metabolism or antigenic variation functional categories were enriched among our prioritized candidate genes. Genes were then analyzed to determine if they interact with cyclins or other proteins known to be involved in the regulation of cell cycle. Conclusions We show that the divergent proliferation rate between a drug resistant and drug sensitive parent clone is under genetic regulation and is segregating as a complex trait in 34 progeny. We map a major locus along with additional secondary effects, and use the wealth of genome data to identify key candidate genes. Of particular interest are a nucleosome assembly protein (PFL0185c, a Zinc finger transcription factor (PFL0465c both on chromosome 12 and a ribosomal protein L7Ae-related on chromosome 4 (PFD0960c.

  18. Proteomic analysis revealed alterations of the Plasmodium falciparum metabolism following salicylhydroxamic acid exposure

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    Torrentino-Madamet M

    2011-09-01

    Full Text Available Marylin Torrentino-Madamet1, Lionel Almeras2, Christelle Travaillé1, Véronique Sinou1, Matthieu Pophillat3, Maya Belghazi4, Patrick Fourquet3, Yves Jammes5, Daniel Parzy11UMR-MD3, Université de la Méditerranée, Antenne IRBA de Marseille (IMTSSA, Le Pharo, 2Unité de Recherche en Biologie et Epidémiologie Parasitaires, Antenne IRBA de Marseille (IMTSSA, Le Pharo, 3Centre d'Immunologie de Marseille Luminy, Institut National de la Santé et de la Recherche Médicale, Centre National de la Recherche Scientifique, Université de la Méditerranée, 4Centre d'Analyse Protéomique de Marseille, Institut Fédératif de Recherche Jean Roche, Faculté de Médecine Nord, 5UMR-MD2, Physiologie et Physiopathologie en Conditions d'Oxygénations Extrêmes, Institut Fédératif de Recherche Jean Roche, Faculté de Médecine Nord, Marseille, FranceObjectives: Although human respiratory metabolism is characterized by the mitochondrial electron transport chain, some organisms present a “branched respiratory chain.” This branched pathway includes both a classical and an alternative respiratory chain. The latter involves an alternative oxidase. Though the Plasmodium falciparum alternative oxidase is not yet identified, a specific inhibitor of this enzyme, salicylhydroxamic acid (SHAM, showed a drug effect on P. falciparum respiratory function using oxygen consumption measurements. The present study aimed to highlight the metabolic pathways that are affected in P. falciparum following SHAM exposure.Design: A proteomic approach was used to analyze the P. falciparum proteome and determine the metabolic pathways altered following SHAM treatment. To evaluate the SHAM effect on parasite growth, the phenotypic alterations of P. falciparum after SHAM or/and hyperoxia exposure were observed.Results: After SHAM exposure, 26 proteins were significantly deregulated using a fluorescent two dimensional-differential gel electrophoresis. Among these deregulated proteins

  19. In vivo efficacy of artemether-lumefantrine against uncomplicated Plasmodium falciparum malaria in Central Ethiopia

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    Jima Daddi

    2011-07-01

    Full Text Available Abstract Background In vivo efficacy assessments of the first-line treatments for Plasmodium falciparum malaria are essential for ensuring effective case management. In Ethiopia, artemether-lumefantrine (AL has been the first-line treatment for uncomplicated P. falciparum malaria since 2004. Methods Between October and November 2009, we conducted a 42-day, single arm, open label study of AL for P. falciparum in individuals >6 months of age at two sites in Oromia State, Ethiopia. Eligible patients who had documented P. falciparum mono-infection were enrolled and followed according to the standard 2009 World Health Organization in vivo drug efficacy monitoring protocol. The primary and secondary endpoints were PCR uncorrected and corrected cure rates, as measured by adequate clinical and parasitological response on days 28 and 42, respectively. Results Of 4426 patients tested, 120 with confirmed falciparum malaria were enrolled and treated with AL. Follow-up was completed for 112 patients at day 28 and 104 patients at day 42. There was one late parasitological failure, which was classified as undetermined after genotyping. Uncorrected cure rates at both day 28 and 42 for the per protocol analysis were 99.1% (95% CI 95.1-100.0; corrected cure rates at both day 28 and 42 were 100.0%. Uncorrected cure rates at day 28 and 42 for the intention to treat analysis were 93.3% (95% CI 87.2-97.1 and 86.6% (95% CI 79.1-92.1, respectively, while the corrected cure rates at day 28 and 42 were 94.1% (95% CI 88.2-97.6 and 87.3% (95% CI 79.9-92.7, respectively. Using survival analysis, the unadjusted cure rate was 99.1% and 100.0% adjusted by genotyping for day 28 and 42, respectively. Eight P. falciparum patients (6.7% presented with Plasmodium vivax infection during follow-up and were excluded from the per protocol analysis. Only one patient had persistent parasitaemia at day 3. No serious adverse events were reported, with cough and nausea/vomiting being the

  20. In vitro evaluation of verapamil and other modulating agents in Brazilian chloroquine-resistant Plasmodium falciparum isolates Avaliação in vitro do verapamil e de outros agentes moduladores em isolados de Plasmodium falciparum resistentes à cloroquina

    Directory of Open Access Journals (Sweden)

    Carla M.S. Menezes

    2003-01-01

    Full Text Available Verapamil, was assayed to record its modulating effect upon Brazilian Plasmodium falciparum isolates resistant to chloroquine. Other cardiovascular drugs known to be modulating agents in resistant malaria and/or multidrug-resistant neoplasias, including nifedipine, nitrendipine, diltiazem and propranolol, were also evaluated. Concentrations similar to those for cardiovascular therapy were used in the in vitro microtechnique for antimalarial drug susceptibility. Intrinsic antiplasmodial activity was observed from the lowest concentrations without a significant modulating action. Other reported modulating agents, such as the antipsychotic drug trifluoperazine and the antidepressants desipramine and imipramine, demonstrated similar responses under the same experimental conditions. Results suggest a much higher susceptibility of Brazilian strains, as well as an indifferent behaviour in relation to modulating agents.Verapamil foi ensaiado quanto ao efeito modulador em isolados brasileiros de Plasmodium falciparum resistentes à cloroquina. Outros agentes cardiovasculares, considerados como moduladores da resistência em malária e/ou em neoplasias multiresistentes a fármacos, como nifedipino, nitrendipino, diltiazem e propranolol foram ensaiados quanto ao mesmo efeito. Concentrações semelhantes às da terapia cardiovascular foram empregadas no ensaio de microtécnica de sensibilidade para fármacos antimaláricos. Atividade antiplasmódica intrínsica foi observada desde as menores concentrações, sem, entretanto, ocorrência de modulação significativa da resistência. Sob as mesmas condições experimentais, respostas semelhantes foram observadas para outros agentes moduladores conhecidos como o antipsicótico trifluoperazina e os antidepressivos desipramina e imipramina. Em conjunto, estes resultados sugerem alta sensibilidade e comportamento indiferente de cepas brasileiras ao efeito de agentes moduladores da resistência.

  1. 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.

  2. The ferredoxin-NADP+ reductase/ferredoxin electron transfer system of Plasmodium falciparum.

    Science.gov (United States)

    Balconi, Emanuela; Pennati, Andrea; Crobu, Danila; Pandini, Vittorio; Cerutti, Raffaele; Zanetti, Giuliana; Aliverti, Alessandro

    2009-07-01

    In the apicoplast of apicomplexan parasites, plastidic-type ferredoxin and ferredoxin-NADP(+) reductase (FNR) form a short electron transport chain that provides reducing power for the synthesis of isoprenoid precursors. These proteins are attractive targets for the development of novel drugs against diseases such as malaria, toxoplasmosis, and coccidiosis. We have obtained ferredoxin and FNR of both Toxoplasma gondii and Plasmodium falciparum in recombinant form, and recently we solved the crystal structure of the P. falciparum reductase. Here we report on the functional properties of the latter enzyme, which differ markedly from those of homologous FNRs. In the physiological reaction, P. falciparum FNR displays a k(cat) five-fold lower than those usually determined for plastidic-type FNRs. By rapid kinetics, we found that hydride transfer between NADPH and protein-bound FAD is slower in the P. falciparum enzyme. The redox properties of the enzyme were determined, and showed that the FAD semiquinone species is highly destabilized. We propose that these two features, i.e. slow hydride transfer and unstable FAD semiquinone, are responsible for the poor catalytic efficiency of the P. falciparum enzyme. Another unprecedented feature of the malarial parasite FNR is its ability to yield, under oxidizing conditions, an inactive dimeric form stabilized by an intermolecular disulfide bond. Here we show that the monomerdimer interconversion can be controlled by oxidizing and reducing agents that are possibly present within the apicoplast, such as H(2)O(2), glutathione, and lipoate. This finding suggests that modulation of the quaternary structure of P. falciparum FNR might represent a regulatory mechanism, although this needs to be verified in vivo.

  3. Biosynthesis of GDP-fucose and Other Sugar Nucleotides in the Blood Stages of Plasmodium falciparum*

    Science.gov (United States)

    Sanz, Sílvia; Bandini, Giulia; Ospina, Diego; Bernabeu, Maria; Mariño, Karina; Fernández-Becerra, Carmen; Izquierdo, Luis

    2013-01-01

    Carbohydrate structures play important roles in many biological processes, including cell adhesion, cell-cell communication, and host-pathogen interactions. Sugar nucleotides are activated forms of sugars used by the cell as donors for most glycosylation reactions. Using a liquid chromatography-tandem mass spectrometry-based method, we identified and quantified the pools of UDP-glucose, UDP-galactose, UDP-N-acetylglucosamine, GDP-mannose, and GDP-fucose in Plasmodium falciparum intraerythrocytic life stages. We assembled these data with the in silico functional reconstruction of the parasite metabolic pathways obtained from the P. falciparum annotated genome, exposing new active biosynthetic routes crucial for further glycosylation reactions. Fucose is a sugar present in glycoconjugates often associated with recognition and adhesion events. Thus, the GDP-fucose precursor is essential in a wide variety of organisms. P. falciparum presents homologues of GDP-mannose 4,6-dehydratase and GDP-l-fucose synthase enzymes that are active in vitro, indicating that most GDP-fucose is formed by a de novo pathway that involves the bioconversion of GDP-mannose. Homologues for enzymes involved in a fucose salvage pathway are apparently absent in the P. falciparum genome. This is in agreement with in vivo metabolic labeling experiments showing that fucose is not significantly incorporated by the parasite. Fluorescence microscopy of epitope-tagged versions of P. falciparum GDP-mannose 4,6-dehydratase and GDP-l-fucose synthase expressed in transgenic 3D7 parasites shows that these enzymes localize in the cytoplasm of P. falciparum during the intraerythrocytic developmental cycle. Although the function of fucose in the parasite is not known, the presence of GDP-fucose suggests that the metabolite may be used for further fucosylation reactions. PMID:23615908

  4. Biosynthesis of GDP-fucose and other sugar nucleotides in the blood stages of Plasmodium falciparum.

    Science.gov (United States)

    Sanz, Sílvia; Bandini, Giulia; Ospina, Diego; Bernabeu, Maria; Mariño, Karina; Fernández-Becerra, Carmen; Izquierdo, Luis

    2013-06-07

    Carbohydrate structures play important roles in many biological processes, including cell adhesion, cell-cell communication, and host-pathogen interactions. Sugar nucleotides are activated forms of sugars used by the cell as donors for most glycosylation reactions. Using a liquid chromatography-tandem mass spectrometry-based method, we identified and quantified the pools of UDP-glucose, UDP-galactose, UDP-N-acetylglucosamine, GDP-mannose, and GDP-fucose in Plasmodium falciparum intraerythrocytic life stages. We assembled these data with the in silico functional reconstruction of the parasite metabolic pathways obtained from the P. falciparum annotated genome, exposing new active biosynthetic routes crucial for further glycosylation reactions. Fucose is a sugar present in glycoconjugates often associated with recognition and adhesion events. Thus, the GDP-fucose precursor is essential in a wide variety of organisms. P. falciparum presents homologues of GDP-mannose 4,6-dehydratase and GDP-L-fucose synthase enzymes that are active in vitro, indicating that most GDP-fucose is formed by a de novo pathway that involves the bioconversion of GDP-mannose. Homologues for enzymes involved in a fucose salvage pathway are apparently absent in the P. falciparum genome. This is in agreement with in vivo metabolic labeling experiments showing that fucose is not significantly incorporated by the parasite. Fluorescence microscopy of epitope-tagged versions of P. falciparum GDP-mannose 4,6-dehydratase and GDP-L-fucose synthase expressed in transgenic 3D7 parasites shows that these enzymes localize in the cytoplasm of P. falciparum during the intraerythrocytic developmental cycle. Although the function of fucose in the parasite is not known, the presence of GDP-fucose suggests that the metabolite may be used for further fucosylation reactions.

  5. Influence of age and previous diet of Anopheles gambiae on the infectivity of natural Plasmodium falciparum gametocytes from human volunteers

    OpenAIRE

    Okech, Bernard A.; Louis C Gouagna; Kabiru, Ephantus W; Beier, John C.; Yan, Guiyun; Githure, John I

    2004-01-01

    The effect of age and dietary factors of Anopheles gambiae (Diptera: Culicidae) on the infectivity of natural Plasmodium falciparum parasites was studied. Mosquitoes of various ages (1–3, 4–7 and 8–11 day old) and those fed blood (either single or double meals) and sugar meals were experimentally co-infected with P. falciparum gametocytes obtained from different naturally infected human volunteers. On day 7, midguts were examined for oocyst infection to determine whether mosquito age or diets...

  6. Perturbation and proinflammatory type activation of Vd1+ gamma delta T cells in African children with Plasmodium falciparum malaria

    DEFF Research Database (Denmark)

    Hviid, L; Kurtzhals, J A; Adabayeri, V

    2001-01-01

    of Plasmodium falciparum malaria in Ghanaian children and they can constitute 30 to 50% of all T cells shortly after initiation of antimalarial chemotherapy. The bulk of the gamma delta T cells involved in this perturbation expressed V delta 1 and had a highly activated phenotype. Analysis of the T...... of the expanded V delta 1(+) T-cell population in this group of semi-immune P. falciparum malaria patients....

  7. The Phosphoproteomes of Plasmodium falciparum and Toxoplasma gondii reveal unusual adaptations within and beyond the parasites’ boundaries

    OpenAIRE

    Treeck, Moritz; Sanders, John L.; Elias, Joshua E.; John C Boothroyd

    2011-01-01

    Plasmodium falciparum and Toxoplasma gondii are obligate intracellular apicomplexan parasites that rapidly invade and extensively modify host cells. Protein phosphorylation is one mechanism by which these parasites can control such processes. Here we present a phosphoproteome analysis of peptides enriched from schizont stage P. falciparum and T. gondii tachyzoites that are either “intracellular” or purified away from host material. Using liquid chromatography and tandem mass-spectrometry we i...

  8. Schistosoma haematobium and Plasmodium falciparum co-infection with protection against Plasmodium falciparum ma-laria in Nigerian children

    Institute of Scientific and Technical Information of China (English)

    Nmorsi OPG; Isaac C; Ukwandu NCD; Ekundayo AO; Ekozien MI

    2009-01-01

    Objective:Malaria remains the single leading killer of children in sub -Sahara Africa and Schistosomiasis is considered to be second to malaria in global importance.Co -infection of malaria and urinary schistosomiasis has been reported to exacerbate disease morbidity such as anaemia.In different part of the globe,the co -in-fection between malaria and schistosomiasis provides some protections on the infected persons.The protective effect of this co -infection elucidated immunologically using cytokines is lacking in our locality.Methods:U-rine and blood samples obtained from the 160 volunteers were subjected to standard parasitological techniques for diagnosis of urinary schistosomiasis and malaria respectively.Blood samples collected from these volunteers comprising 80 children with schistosomiasis and malaria and the 80 children who had malaria only were subjec-ted to cytokines concentration determination using commercial standard enzyme linked immunosorbent assay kits (Abcam,UK).Results:Eighty participants with co -infection had a mean malarial parasitaemia of 662 ±201.1 μL while the 80 participants with only P.falciparum malaria had a mean malarial parasiteamia of 5943 ±3270.7μL.Also the volunteers had mean haemoglobin of 11.2 g/dL for co -infected individuals and 5.7 g/dL for participants with single infection of malaria.The serum cytokine levels of the children with S. haematobium and P.falciparum and only P.falciparum infection are as follows;interleukin -4 (16.6 pg/mL versus 5.2 pg/mL),IL -5 (501.3 pg/mL versus 357.5 pg/mL);IL -8 (2 550 pg/mL versus 309 pg/mL),IL -10 (273 pg/mL versus 290 pg/mL),TNF -α(25 pg/mL versus 290 pg/mL)and IFN -γ(21.9 pg/mL versus 2.5 pg/mL).The TNF -α/IL -10 ratio is 7 for the children with co -infection while those with only P.falciparum malaria infection had a TNF -α/IL -10 ratio of 0.9.Conclusion:We con-clude that the elevated IL -4,IL -5,IL -8 and IFN -γconcentration induced by schistosomiasis altered the Th1 /Th 2

  9. 5-Aminopyrazole-4-carboxamide analogues are selective inhibitors of Plasmodium falciparum microgametocyte exflagellation and potential malaria transmission blocking agents.

    Science.gov (United States)

    Huang, Wenlin; Hulverson, Matthew A; Zhang, Zhongsheng; Choi, Ryan; Hart, Kevin J; Kennedy, Mark; Vidadala, Rama Subba Rao; Maly, Dustin J; Van Voorhis, Wesley C; Lindner, Scott E; Fan, Erkang; Ojo, Kayode K

    2016-11-15

    Plasmodium falciparum calcium-dependent protein kinase 4 (PfCDPK4) is essential for the exflagellation of male gametocytes. Inhibition of PfCDPK4 is an effective way of blocking the transmission of malaria by mosquitoes. A series of 5-aminopyrazole-4-carboxamide analogues are demonstrated to be potent inhibitors of PfCDPK4. The compounds are also able to block exflagellation of Plasmodium falciparum male gametocytes without observable toxicity to mammalian cells. Copyright © 2016 Elsevier Ltd. All rights reserved.

  10. Plasmodium falciparum spermidine synthase inhibition results in unique perturbation-specific effects observed on transcript, protein and metabolite levels

    CSIR Research Space (South Africa)

    Becker, JVW

    2010-01-01

    Full Text Available :235 http://www.biomedcentral.com/1471-2164/11/235 Open AccessR E S E A R C H A R T I C L E Research articlePlasmodium falciparum spermidine synthase inhibition results in unique perturbation-specific effects observed on transcript, protein... and metabolite levels John VW Becker†1, Linda Mtwisha†1, Bridget G Crampton1, Stoyan Stoychev1, Anna C van Brummelen1, Shaun Reeksting2, Abraham I Louw2, Lyn-Marie Birkholtz2 and Dalu T Mancama*1 Abstract Background: Plasmodium falciparum, the causative agent...

  11. Role of Calcium Signaling in the Transcriptional Regulation of the Apicoplast Genome of Plasmodium falciparum

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    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.

  12. Mechanisms of protective immunity against asexual blood stages of Plasmodium falciparum in the experimental host Saimiri

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    J. Gysin

    1992-01-01

    Full Text Available In the Saimiri monkey, an experimental host for human malaria, acquired protection against Plasmodium falciparum blood stages depends on the IgG antibody populations developed. In vivo protective anti-falciparum activity of IgG antibodies is correlated with the in vivo opsonizing activity promoting phagocytosis of parasited red bloood cells. In contrast, non protective antibodies inhibit this mechanism by competing at the target level. A similar phenomenon can be and human infection. Anti-cytoadherent and anti-rosette antibodies developed by Saimiri and humans prevent the development of physiopathological events like cerebral malaria which can also occur in this experimental host. Furthermore, transfer to protective human anti-falciparum IgG antibodies into infected Saimiri monkeys exerts an anti parasite activity as efficient as that observed when it is transfered into acute falciparum malaria patients, making the Saimiri an even more attractive host. Studies on the role of immunocompetent cells in the protective immune reponse are still in their infancy, however the existance of a restricted polymorphism of MHC II class molecules in the Saimiri confers additional theoretical and practical importance to this model.

  13. Immunogenicity and in vitro Protective Efficacy of a Recombinant Multistage Plasmodium falciparum Candidate Vaccine

    Science.gov (United States)

    Shi, Ya Ping; Hasnain, Seyed E.; Sacci, John B.; Holloway, Brian P.; Fujioka, Hisashi; Kumar, Nirbhay; Wohlhueter, Robert; Hoffman, Stephen L.; Collins, William E.; Lal, Altaf A.

    1999-02-01

    Compared with a single-stage antigen-based vaccine, a multistage and multivalent Plasmodium falciparum vaccine would be more efficacious by inducing "multiple layers" of immunity. We have constructed a synthetic gene that encodes for 12 B cell, 6 T cell proliferative, and 3 cytotoxic T lymphocyte epitopes derived from 9 stage-specific P. falciparum antigens corresponding to the sporozoite, liver, erythrocytic asexual, and sexual stages. The gene was expressed in the baculovirus system, and a 41-kDa antigen, termed CDC/NIIMALVAC-1, was purified. Immunization in rabbits with the purified protein in the presence of different adjuvants generated antibody responses that recognized vaccine antigen, linear peptides contained in the vaccine, and all stages of P. falciparum. In vitro assays of protection revealed that the vaccine-elicited antibodies strongly inhibited sporozoite invasion of hepatoma cells and growth of blood-stage parasites in the presence of monocytes. These observations demonstrate that a multicomponent, multistage malaria vaccine can induce immune responses that inhibit parasite development at multiple stages. The rationale and approach used in the development of a multicomponent P. falciparum vaccine will be useful in the development of a multispecies human malaria vaccine and vaccines against other infectious diseases.

  14. Expression of cleaved caspase-3 in renal tubular cells in Plasmodium falciparum malaria patients.

    Science.gov (United States)

    Wichapoon, Benjamas; Punsawad, Chuchard; Viriyavejakul, Parnpen

    2017-01-01

    In Plasmodium falciparum malaria, the clinical manifestation of acute kidney injury (AKI) is commonly associated with acute tubular necrosis (ATN) in the kidney tissues. Renal tubular cells often exhibit various degrees of cloudy swelling, cell degeneration, and frank necrosis. To study individual cell death, this study evaluates the degree of renal tubular necrosis in association with apoptosis in malarial kidneys. Kidney tissues from P. falciparum malaria with AKI (10 cases), and without AKI (10 cases) were evaluated for tubular pathology. Normal kidney tissues from 10 cases served as controls. Tubular necrosis was assessed quantitatively in kidney tissues infected with P. falciparum malaria, based on histopathological evaluation. In addition, the occurrence of apoptosis was investigated using cleaved caspase-3 marker. Correlation between tubular necrosis and apoptosis was analyzed. Tubular necrosis was found to be highest in P. falciparum malaria patients with AKI (36.44% ± 3.21), compared to non-AKI (15.88% ± 1.63) and control groups (2.58% ± 0.39) (all p < 0.001). In the AKI group, the distal tubules showed a significantly higher degree of tubular necrosis than the proximal tubules (p = 0.021) and collecting tubules (p = 0.033). Tubular necrosis was significantly correlated with the level of serum creatinine (r = 0.596, p = 0.006), and the occurrence of apoptosis (r = 0.681, p = 0.001). In malarial AKI, the process of apoptosis occurs in ATN. © 2016 Asian Pacific Society of Nephrology.

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

    Science.gov (United States)

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

    2006-10-01

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

  16. 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.

  17. In-vitro antimalarial activity of azithromycin against chloroquine sensitive and chloroquine resistant Plasmodium falciparum.

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    Biswas S

    2001-10-01

    Full Text Available BAKGROUND: The spread of drug resistance in Plasmodium falciparum has made the situation essential to look into new effective therapeutic agents like antibiotics. Azithromycin is a potential, chemotherapeutic agent which possesses antimalarial activity and favourable pharmacokinetic properties. It is an azalide microbiocide derived semi-synthetically from macrolide erythromycin. Like other antibiotics, the azalide azithromycin has ability to inhibit protein synthesis on 70S ribosomes. SETTINGS: Experimental study. SUBJECTS AND METHODS: The parasiticidal profile was studied in five chloroquine sensitive and five chloroquine resistant P. falciparum isolates obtained from various places of India. The antimalarial activity was evaluated in P. falciparum schizont maturation by short term culture for 24 hours and by exposing the parasites to the drug for 96 hours. Parasites synchronized at ring stage were put for culture with various concentrations of azithromycin dihydrate (0.01-40 micro/ml. RESULTS: At highest concentration (40 micro/ml, parasite growth was inhibited totally in all 10 isolates. Antimalarial activity at 96 hours was greater than at 24 hours in both chloroquine sensitive and resistant parasites, which may indicate that the inhibition of parasite growth may occur at clinically achievable concentration of the drug when parasites were exposed for several asexual cycles. CONCLUSION: Azithromycin shows a potential for eventual use alone or in combination in the treatment of chloroquine sensitive and resistant P. falciparum malaria.

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

    Science.gov (United States)

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

    2006-03-01

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

  19. Insights into the pyrimidine biosynthetic pathway of human malaria parasite Plasmodium falciparum as chemotherapeutic target.

    Science.gov (United States)

    Krungkrai, Sudaratana R; Krungkrai, Jerapan

    2016-06-01

    Malaria is a major cause of morbidity and mortality in humans. Artemisinins remain as the first-line treatment for Plasmodium falciparum (P. falciparum) malaria although drug resistance has already emerged and spread in Southeast Asia. Thus, to fight this disease, there is an urgent need to develop new antimalarial drugs for malaria chemotherapy. Unlike human host cells, P. falciparum cannot salvage preformed pyrimidine bases or nucleosides from the extracellular environment and relies solely on nucleotides synthesized through the de novo biosynthetic pathway. This review presents significant progress on understanding the de novo pyrimidine pathway and the functional enzymes in the human parasite P. falciparum. Current knowledge in genomics and metabolomics are described, particularly focusing on the parasite purine and pyrimidine nucleotide metabolism. These include gene annotation, characterization and molecular mechanism of the enzymes that are different from the human host pathway. Recent elucidation of the three-dimensional crystal structures and the catalytic reactions of three enzymes: dihydroorotate dehydrogenase, orotate phosphoribosyltransferase, and orotidine 5'-monophosphate decarboxylase, as well as their inhibitors are reviewed in the context of their therapeutic potential against malaria.

  20. Survey of in vivo sensitivity to chloroquine by Plasmodium falciparum and P. vivax in Lombok, Indonesia.

    Science.gov (United States)

    Fryauff, D J; Baird, J K; Candradikusuma, D; Masbar, S; Sutamihardja, M A; Leksana, B; Tuti, S; Marwoto, H; Richie, T; Romzan, A

    1997-02-01

    A malariometric survey was conducted in 14 villages of Sekotong district, in Lombok, Indonesia during October 1994. Point prevalence of malaria ranged from 0% to 15% in the surveyed villages, averaging 6% overall, and Plasmodium falciparum accounted for 63% of the infections. Forty-nine patients with uncomplicated malaria and parasite counts ranging from 40 to 10,800 asexual forms/microliter were enrolled in a 28-day in vivo test of chloroquine sensitivity. All subjects received a supervised therapeutic regimen of chloroquine (25 mg base/kg over a 48-hr period) and parasitemia and symptoms were closely monitored for 28 days. Asexual parasites were eliminated within four days in the 29 P. falciparum and 20 P. vivax study patients enrolled. The cumulative incidence of therapeutic failure (recurrent symptomatic parasitemia) among P. falciparum cases at days 7, 14, and 28 was 7%, 10%, and 14% (4 of 29), respectively. However in all four cases, parasitemias recurred against chloroquine blood levels below the minimally effective concentration (MEC) of 200 ng/ml and do not confirm chloroquine resistance. All 20 P. vivax parasitemias were sensitive to chloroquine and the blood remained clear, with the exception of one case in which an asymptomatic parasitemia appeared on day 28. Parasitemias by P. falciparum and P. vivax that were observed before supervised therapy, but in the presence of whole blood chloroquine above normally suppressive MEC levels, suggest resistance to suppressive or prophylactic regimens of chloroquine.