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Sample records for plasmodium falciparum pfpmt

  1. Crystal structure of phosphoethanolamine methyltransferase from Plasmodium falciparum in complex with amodiaquine

    SciTech Connect

    Lee, Soon Goo; Alpert, Tara D.; Jez, Joseph M.

    2012-07-17

    Phosphoethanolamine N-methyltransferase (PMT) is essential for phospholipid biogenesis in the malarial parasite Plasmodium falciparum. PfPMT catalyzes the triple methylation of phosphoethanolamine to produce phosphocholine, which is then used for phosphatidylcholine synthesis. Here we describe the 2.0 {angstrom} resolution X-ray crystal structure of PfPMT in complex with amodiaquine. To better characterize inhibition of PfPMT by amodiaquine, we determined the IC{sub 50} values of a series of aminoquinolines using a direct radiochemical assay. Both structural and functional analyses provide a possible approach for the development of new small molecule inhibitors of PfPMT.

  2. Biochemical and genetic analysis of the phosphoethanolamine methyltransferase of the human malaria parasite Plasmodium falciparum.

    PubMed

    Reynolds, Jennifer M; Takebe, Sachiko; Choi, Jae-Yeon; El Bissati, Kamal; Witola, William H; Bobenchik, April M; Hoch, Jeffrey C; Voelker, Dennis R; Mamoun, Choukri Ben

    2008-03-21

    The PfPMT enzyme of Plasmodium falciparum, the agent of severe human malaria, is a member of a large family of known and predicted phosphoethanolamine methyltransferases (PMTs) recently identified in plants, worms, and protozoa. Functional studies in P. falciparum revealed that PfPMT plays a critical role in the synthesis of phosphatidylcholine via a plant-like pathway involving serine decarboxylation and phosphoethanolamine methylation. Despite their important biological functions, PMT structures have not yet been solved, and nothing is known about which amino acids in these enzymes are critical for catalysis and binding to S-adenosyl-methionine and phosphoethanolamine substrates. Here we have performed a mutational analysis of PfPMT focused on 24 residues within and outside the predicted catalytic motif. The ability of PfPMT to complement the choline auxotrophy of a yeast mutant defective in phospholipid methylation enabled us to characterize the activity of the PfPMT mutants. Mutations in residues Asp-61, Gly-83 and Asp-128 dramatically altered PfPMT activity and its complementation of the yeast mutant. Our analyses identify the importance of these residues in PfPMT activity and set the stage for advanced structural understanding of this class of enzymes.

  3. In vivo evidence for the specificity of Plasmodium falciparum phosphoethanolamine methyltransferase and its coupling to the Kennedy pathway.

    PubMed

    Pessi, Gabriella; Choi, Jae-Yeon; Reynolds, Jennifer M; Voelker, Dennis R; Mamoun, Choukri Ben

    2005-04-01

    Unlike humans and yeast, Plasmodium falciparum, the agent of the most severe form of human malaria, utilizes host serine as a precursor for the synthesis of phosphatidylcholine via a plant-like pathway involving phosphoethanolamine methylation. The monopartite phosphoethanolamine methyltransferase, Pfpmt, plays an important role in the biosynthetic pathway of this major phospholipid by providing the precursor phosphocholine via a three-step S-adenosyl-L-methionine-dependent methylation of phosphoethanolamine. In vitro studies showed that Pfpmt has strong specificity for phosphoethanolamine. However, the in vivo substrate (phosphoethanolamine or phosphatidylethanolamine) is not yet known. We used yeast as a surrogate system to express Pfpmt and provide genetic and biochemical evidence demonstrating the specificity of Pfpmt for phosphoethanolamine in vivo. Wild-type yeast cells, which inherently lack phosphoethanolamine methylation, acquire this activity as a result of expression of Pfpmt. The Pfpmt restores the ability of a yeast mutant pem1Deltapem2Delta lacking the phosphatidylethanolamine methyltransferase genes to grow in the absence of choline. Lipid analysis of the Pfpmt-complemented pem1Deltapem2Delta strain demonstrates the synthesis of phosphatidylcholine but not the intermediates of phosphatidylethanolamine transmethylation. Complementation of the pem1Deltapem2Delta mutant relies on specific methylation of phosphoethanolamine but not phosphatidylethanolamine. Interestingly, a mutation in the yeast choline-phosphate cytidylyltransferase gene abrogates the complementation by Pfpmt thus demonstrating that Pfpmt activity is directly coupled to the Kennedy pathway for the de novo synthesis of phosphatidylcholine.

  4. Identification of inhibitors of Plasmodium falciparum phosphoethanolamine methyltransferase using an enzyme-coupled transmethylation assay

    PubMed Central

    2010-01-01

    Background The phosphoethanolamine methyltransferase, PfPMT, of the human malaria parasite Plasmodium falciparum, a member of a newly identified family of phosphoethanolamine methyltransferases (PMT) found solely in some protozoa, nematodes, frogs, and plants, is involved in the synthesis of the major membrane phospholipid, phosphatidylcholine. PMT enzymes catalyze a three-step S-adenosylmethionine-dependent methylation of the nitrogen atom of phosphoethanolamine to form phosphocholine. In P. falciparum, this activity is a limiting step in the pathway of synthesis of phosphatidylcholine from serine and plays an important role in the development, replication and survival of the parasite within human red blood cells. Results We have employed an enzyme-coupled methylation assay to screen for potential inhibitors of PfPMT. In addition to hexadecyltrimethylammonium, previously known to inhibit PfPMT, two compounds dodecyltrimethylammonium and amodiaquine were also found to inhibit PfPMT activity in vitro. Interestingly, PfPMT activity was not inhibited by the amodiaquine analog, chloroquine, or other aminoquinolines, amino alcohols, or histamine methyltransferase inhibitors. Using yeast as a surrogate system we found that unlike wild-type cells, yeast mutants that rely on PfPMT for survival were sensitive to amodiaquine, and their phosphatidylcholine biosynthesis was inhibited by this compound. Furthermore NMR titration studies to characterize the interaction between amoidaquine and PfPMT demonstrated a specific and concentration dependent binding of the compound to the enzyme. Conclusion The identification of amodiaquine as an inhibitor of PfPMT in vitro and in yeast, and the biophysical evidence for the specific interaction of the compound with the enzyme will set the stage for the development of analogs of this drug that specifically inhibit this enzyme and possibly other PMTs. PMID:20085640

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

    PubMed

    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. Plasmodium falciparum malaria.

    PubMed

    Shetty, A K; Steele, R W

    1999-01-01

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

  7. An Alternative Mechanism for the Methylation of Phosphoethanolamine Catalyzed by Plasmodium falciparum Phosphoethanolamine Methyltransferase*♦

    PubMed Central

    Saen-oon, Suwipa; Lee, Soon Goo; Jez, Joseph M.; Guallar, Victor

    2014-01-01

    The phosphobase methylation pathway catalyzed by the phosphoethanolamine methyltransferase in Plasmodium falciparum (PfPMT), the malaria parasite, offers an attractive target for anti-parasitic drug development. PfPMT methylates phosphoethanolamine (pEA) to phosphocholine for use in membrane biogenesis. Quantum mechanics and molecular mechanics (QM/MM) calculations tested the proposed reaction mechanism for methylation of pEA involving the previously identified Tyr-19–His-132 dyad, which indicated an energetically unfavorable mechanism. Instead, the QM/MM calculations suggested an alternative mechanism involving Asp-128. The reaction coordinate involves the stepwise transfer of a proton to Asp-128 via a bridging water molecule followed by a typical Sn2-type methyl transfer from S-adenosylmethionine to pEA. Functional analysis of the D128A, D128E, D128Q, and D128N PfPMT mutants shows a loss of activity with pEA but not with the final substrate of the methylation pathway. X-ray crystal structures of the PfPMT-D128A mutant in complex with S-adenosylhomocysteine and either pEA or phosphocholine reveal how mutation of Asp-128 disrupts a hydrogen bond network in the active site. The combined QM/MM, biochemical, and structural studies identify a key role for Asp-128 in the initial step of the phosphobase methylation pathway in Plasmodium and provide molecular insight on the evolution of multiple activities in the active site of the PMT. PMID:25288796

  8. Structure and Reaction Mechanism of Phosphoethanolamine Methyltransferase from the Malaria Parasite Plasmodium falciparum

    PubMed Central

    Lee, Soon Goo; Kim, Youngchang; Alpert, Tara D.; Nagata, Akina; Jez, Joseph M.

    2012-01-01

    In the malarial parasite Plasmodium falciparum, a multifunctional phosphoethanolamine methyltransferase (PfPMT) catalyzes the methylation of phosphoethanolamine (pEA) to phosphocholine for membrane biogenesis. This pathway is also found in plant and nematodes, but PMT from these organisms use multiple methyltransferase domains for the S-adenosylmethionine (AdoMet) reactions. Because PfPMT is essential for normal growth and survival of Plasmodium and is not found in humans, it is an antiparasitic target. Here we describe the 1.55 Å resolution crystal structure of PfPMT in complex with AdoMet by single-wavelength anomalous dispersion phasing. In addition, 1.19–1.52 Å resolution structures of PfPMT with pEA (substrate), phosphocholine (product), sinefungin (inhibitor), and both pEA and S-adenosylhomocysteine bound were determined. These structures suggest that domain rearrangements occur upon ligand binding and provide insight on active site architecture defining the AdoMet and phosphobase binding sites. Functional characterization of 27 site-directed mutants identifies critical active site residues and suggests that Tyr-19 and His-132 form a catalytic dyad. Kinetic analysis, isothermal titration calorimetry, and protein crystallography of the Y19F and H132A mutants suggest a reaction mechanism for the PMT. Not only are Tyr-19 and His-132 required for phosphobase methylation, but they also form a “catalytic” latch that locks ligands in the active site and orders the site for catalysis. This study provides the first insight on this antiparasitic target enzyme essential for survival of the malaria parasite; however, further studies of the multidomain PMT from plants and nematodes are needed to understand the evolutionary division of metabolic function in the phosphobase pathway of these organisms. PMID:22117061

  9. Isoprenoid Biosynthesis in Plasmodium falciparum

    PubMed Central

    Guggisberg, Ann M.; Amthor, Rachel E.

    2014-01-01

    Malaria kills nearly 1 million people each year, and the protozoan parasite Plasmodium falciparum has become increasingly resistant to current therapies. Isoprenoid synthesis via the methylerythritol phosphate (MEP) pathway represents an attractive target for the development of new antimalarials. The phosphonic acid antibiotic fosmidomycin is a specific inhibitor of isoprenoid synthesis and has been a helpful tool to outline the essential functions of isoprenoid biosynthesis in P. falciparum. Isoprenoids are a large, diverse class of hydrocarbons that function in a variety of essential cellular processes in eukaryotes. In P. falciparum, isoprenoids are used for tRNA isopentenylation and protein prenylation, as well as the synthesis of vitamin E, carotenoids, ubiquinone, and dolichols. Recently, isoprenoid synthesis in P. falciparum has been shown to be regulated by a sugar phosphatase. We outline what is known about isoprenoid function and the regulation of isoprenoid synthesis in P. falciparum, in order to identify valuable directions for future research. PMID:25217461

  10. Tetany with Plasmodium falciparum infection.

    PubMed

    Singh, P S; Singh, Neha

    2012-07-01

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

  11. An alternative mechanism for the methylation of phosphoethanolamine catalyzed by Plasmodium falciparum phosphoethanolamine methyltransferase

    DOE PAGES

    Saen-oon, Suwipa; Lee, Soon Goo; Jez, Joseph M.; ...

    2014-10-06

    Here, the phosphobase methylation pathway catalyzed by the phosphoethanolamine methyltransferase in Plasmodium falciparum (PfPMT), the malaria parasite, offers an attractive target for anti-parasitic drug development. PfPMT methylates phosphoethanolamine (pEA) to phosphocholine for use in membrane biogenesis. Quantum mechanics and molecular mechanics (QM/MM) calculations tested the proposed reaction mechanism for methylation of pEA involving the previously identified Tyr-19–His-132 dyad, which indicated an energetically unfavorable mechanism. Instead, the QM/MM calculations suggested an alternative mechanism involving Asp-128. The reaction coordinate involves the stepwise transfer of a proton to Asp-128 via a bridging water molecule followed by a typical Sn2-type methyl transfer from S-adenosylmethioninemore » to pEA. Functional analysis of the D128A, D128E, D128Q, and D128N PfPMT mutants shows a loss of activity with pEA but not with the final substrate of the methylation pathway. X-ray crystal structures of the PfPMT-D128A mutant in complex with S-adenosylhomocysteine and either pEA or phosphocholine reveal how mutation of Asp-128 disrupts a hydrogen bond network in the active site. The combined QM/MM, biochemical, and structural studies identify a key role for Asp-128 in the initial step of the phosphobase methylation pathway in Plasmodium and provide molecular insight on the evolution of multiple activities in the active site of the PMT.« less

  12. An alternative mechanism for the methylation of phosphoethanolamine catalyzed by Plasmodium falciparum phosphoethanolamine methyltransferase.

    PubMed

    Saen-Oon, Suwipa; Lee, Soon Goo; Jez, Joseph M; Guallar, Victor

    2014-12-05

    The phosphobase methylation pathway catalyzed by the phosphoethanolamine methyltransferase in Plasmodium falciparum (PfPMT), the malaria parasite, offers an attractive target for anti-parasitic drug development. PfPMT methylates phosphoethanolamine (pEA) to phosphocholine for use in membrane biogenesis. Quantum mechanics and molecular mechanics (QM/MM) calculations tested the proposed reaction mechanism for methylation of pEA involving the previously identified Tyr-19-His-132 dyad, which indicated an energetically unfavorable mechanism. Instead, the QM/MM calculations suggested an alternative mechanism involving Asp-128. The reaction coordinate involves the stepwise transfer of a proton to Asp-128 via a bridging water molecule followed by a typical Sn2-type methyl transfer from S-adenosylmethionine to pEA. Functional analysis of the D128A, D128E, D128Q, and D128N PfPMT mutants shows a loss of activity with pEA but not with the final substrate of the methylation pathway. X-ray crystal structures of the PfPMT-D128A mutant in complex with S-adenosylhomocysteine and either pEA or phosphocholine reveal how mutation of Asp-128 disrupts a hydrogen bond network in the active site. The combined QM/MM, biochemical, and structural studies identify a key role for Asp-128 in the initial step of the phosphobase methylation pathway in Plasmodium and provide molecular insight on the evolution of multiple activities in the active site of the PMT. © 2014 by The American Society for Biochemistry and Molecular Biology, Inc.

  13. Structure and reaction mechanism of phosphoethanolamine methyltransferase from the malaria parasite Plasmodium falciparum: an antiparasitic drug target.

    PubMed

    Lee, Soon Goo; Kim, Youngchang; Alpert, Tara D; Nagata, Akina; Jez, Joseph M

    2012-01-06

    In the malarial parasite Plasmodium falciparum, a multifunctional phosphoethanolamine methyltransferase (PfPMT) catalyzes the methylation of phosphoethanolamine (pEA) to phosphocholine for membrane biogenesis. This pathway is also found in plant and nematodes, but PMT from these organisms use multiple methyltransferase domains for the S-adenosylmethionine (AdoMet) reactions. Because PfPMT is essential for normal growth and survival of Plasmodium and is not found in humans, it is an antiparasitic target. Here we describe the 1.55 Å resolution crystal structure of PfPMT in complex with AdoMet by single-wavelength anomalous dispersion phasing. In addition, 1.19-1.52 Å resolution structures of PfPMT with pEA (substrate), phosphocholine (product), sinefungin (inhibitor), and both pEA and S-adenosylhomocysteine bound were determined. These structures suggest that domain rearrangements occur upon ligand binding and provide insight on active site architecture defining the AdoMet and phosphobase binding sites. Functional characterization of 27 site-directed mutants identifies critical active site residues and suggests that Tyr-19 and His-132 form a catalytic dyad. Kinetic analysis, isothermal titration calorimetry, and protein crystallography of the Y19F and H132A mutants suggest a reaction mechanism for the PMT. Not only are Tyr-19 and His-132 required for phosphobase methylation, but they also form a "catalytic" latch that locks ligands in the active site and orders the site for catalysis. This study provides the first insight on this antiparasitic target enzyme essential for survival of the malaria parasite; however, further studies of the multidomain PMT from plants and nematodes are needed to understand the evolutionary division of metabolic function in the phosphobase pathway of these organisms.

  14. Chemical genetics of Plasmodium falciparum

    PubMed Central

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

    2010-01-01

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

  15. Plasmodium falciparum picks (on) EPCR

    PubMed Central

    Mosnier, Laurent O.; Fairhurst, Rick M.

    2014-01-01

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

  16. An alternative mechanism for the methylation of phosphoethanolamine catalyzed by Plasmodium falciparum phosphoethanolamine methyltransferase

    SciTech Connect

    Saen-oon, Suwipa; Lee, Soon Goo; Jez, Joseph M.; Guallar, Victor

    2014-10-06

    Here, the phosphobase methylation pathway catalyzed by the phosphoethanolamine methyltransferase in Plasmodium falciparum (PfPMT), the malaria parasite, offers an attractive target for anti-parasitic drug development. PfPMT methylates phosphoethanolamine (pEA) to phosphocholine for use in membrane biogenesis. Quantum mechanics and molecular mechanics (QM/MM) calculations tested the proposed reaction mechanism for methylation of pEA involving the previously identified Tyr-19–His-132 dyad, which indicated an energetically unfavorable mechanism. Instead, the QM/MM calculations suggested an alternative mechanism involving Asp-128. The reaction coordinate involves the stepwise transfer of a proton to Asp-128 via a bridging water molecule followed by a typical Sn2-type methyl transfer from S-adenosylmethionine to pEA. Functional analysis of the D128A, D128E, D128Q, and D128N PfPMT mutants shows a loss of activity with pEA but not with the final substrate of the methylation pathway. X-ray crystal structures of the PfPMT-D128A mutant in complex with S-adenosylhomocysteine and either pEA or phosphocholine reveal how mutation of Asp-128 disrupts a hydrogen bond network in the active site. The combined QM/MM, biochemical, and structural studies identify a key role for Asp-128 in the initial step of the phosphobase methylation pathway in Plasmodium and provide molecular insight on the evolution of multiple activities in the active site of the PMT.

  17. Parasite Lactate Dehydrogenase for Diagnosis of Plasmodium Falciparum. Phase II.

    DTIC Science & Technology

    1997-04-01

    Diagnosis of Plasmodium Falciparum PRINCIPAL INVESTIGATOR: Robert C. Piper, Ph.D. CONTRACTING ORGANIZATION: Flow, Incorporated Portland, Oregon 97201...Phase 11 (24 Mar 95 - 23 Mar 97) 4. TITLE AND SUBTITLE 5. FUNDING NUMBERS Parasite Lactate Dehydrogenase for Diagnosis of Plasmodium Falciparum DAMD...that infected patients become ill. Four species of Plasmodium infect humans. P. falciparum accounts for -85 % of the world’s malaria. P. falciparum is

  18. Congenital Plasmodium falciparum Malaria in Washington, DC.

    PubMed

    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.

  19. Plasmodium falciparum Malaria, Southern Algeria, 2007

    PubMed Central

    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

  20. Gametocytogenesis : the puberty of Plasmodium falciparum

    PubMed Central

    Talman, Arthur M; Domarle, Olivier; McKenzie, F Ellis; Ariey, Frédéric; Robert, Vincent

    2004-01-01

    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. PMID:15253774

  1. Desferrioxamine suppresses Plasmodium falciparum in Aotus monkeys.

    PubMed

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

    1987-02-01

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

  2. Artemisinins target the SERCA of Plasmodium falciparum.

    PubMed

    Eckstein-Ludwig, U; Webb, R J; Van Goethem, I D A; East, J M; Lee, A G; Kimura, M; O'Neill, P M; Bray, P G; Ward, S A; Krishna, S

    2003-08-21

    Artemisinins are extracted from sweet wormwood (Artemisia annua) and are the most potent antimalarials available, rapidly killing all asexual stages of Plasmodium falciparum. Artemisinins are sesquiterpene lactones widely used to treat multidrug-resistant malaria, a disease that annually claims 1 million lives. Despite extensive clinical and laboratory experience their molecular target is not yet identified. Activated artemisinins form adducts with a variety of biological macromolecules, including haem, translationally controlled tumour protein (TCTP) and other higher-molecular-weight proteins. Here we show that artemisinins, but not quinine or chloroquine, inhibit the SERCA orthologue (PfATP6) of Plasmodium falciparum in Xenopus oocytes with similar potency to thapsigargin (another sesquiterpene lactone and highly specific SERCA inhibitor). As predicted, thapsigargin also antagonizes the parasiticidal activity of artemisinin. Desoxyartemisinin lacks an endoperoxide bridge and is ineffective both as an inhibitor of PfATP6 and as an antimalarial. Chelation of iron by desferrioxamine abrogates the antiparasitic activity of artemisinins and correspondingly attenuates inhibition of PfATP6. Imaging of parasites with BODIPY-thapsigargin labels the cytosolic compartment and is competed by artemisinin. Fluorescent artemisinin labels parasites similarly and irreversibly in an Fe2+-dependent manner. These data provide compelling evidence that artemisinins act by inhibiting PfATP6 outside the food vacuole after activation by iron.

  3. Maurer's clefts, the enigma of Plasmodium falciparum

    PubMed Central

    Mundwiler-Pachlatko, Esther; Beck, Hans-Peter

    2013-01-01

    Plasmodium falciparum, the causative agent of malaria, completely remodels the infected human erythrocyte to acquire nutrients and to evade the immune system. For this process, the parasite exports more than 10% of all its proteins into the host cell cytosol, including the major virulence factor PfEMP1 (P. falciparum erythrocyte surface protein 1). This unusual protein trafficking system involves long-known parasite-derived membranous structures in the host cell cytosol, called Maurer’s clefts. However, the genesis, role, and function of Maurer’s clefts remain elusive. Similarly unclear is how proteins are sorted and how they are transported to and from these structures. Recent years have seen a large increase of knowledge but, as yet, no functional model has been established. In this perspective we review the most important findings and conclude with potential possibilities to shed light into the enigma of Maurer’s clefts. Understanding the mechanism and function of these structures, as well as their involvement in protein export in P. falciparum, might lead to innovative control strategies and might give us a handle with which to help to eliminate this deadly parasite. PMID:24284172

  4. Drug Evaluation in the Plasmodium Falciparum - Aotus Model.

    DTIC Science & Technology

    1992-03-23

    AOTUS MODEL PRINCIPAL INVESTIGATOR: Richard N. Rossan, Ph.D. CONTRACTING ORGANIZATION: PROMED TRADING, S.A. P.O. Box 025426, PTY-051 Miami, Florida...91 - 2/28/92) 4. TITLE AND SUBTITLE S. FUNDING NUMBERS DRUG EVALUATION IN THE PLASMODIUM FALCIPARUM - Contract No. AOTUS MODEL DAMD17-91-C-1072 6C...words) Tne Panamanian Autus - PLasmodium falciparum model was used to evaluate potential antimalaria drugs. Neither protriptylene nor tetrandrine, each

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

    PubMed

    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.

  6. New Strategies for Drug Discovery and Development for Plasmodium Falciparum

    DTIC Science & Technology

    2000-01-01

    research working in concert with one another. The goal of this work is to use a molecular genetic approach both in the identification of new drug targets...analysis of critical genes in the Plasmodium falciparum for their role in drug resistance and as potential new drug targets using both the homologous P. falciparum system and the heterologous yeast system.

  7. The Motor Complex of Plasmodium falciparum

    PubMed Central

    Green, Judith L.; Rees-Channer, Roxanne R.; Howell, Stephen A.; Martin, Stephen R.; Knuepfer, Ellen; Taylor, Helen M.; Grainger, Munira; Holder, Anthony A.

    2008-01-01

    Calcium-dependent protein kinases (CDPKs) of Apicomplexan parasites are crucial for the survival of the parasite throughout its life cycle. CDPK1 is expressed in the asexual blood stages of the parasite, particularly late stage schizonts. We have identified two substrates of Plasmodium falciparum CDPK1: myosin A tail domain-interacting protein (MTIP) and glideosome-associated protein 45 (GAP45), both of which are components of the motor complex that generates the force required by the parasite to actively invade host cells. Indirect immunofluorescence shows that CDPK1 localizes to the periphery of P. falciparum merozoites and is therefore suitably located to act on MTIP and GAP45 at the inner membrane complex. A proportion of both GAP45 and MTIP is phosphorylated in schizonts, and we demonstrate that both proteins can be efficiently phosphorylated by CDPK1 in vitro. A primary phosphorylation of MTIP occurs at serine 47, whereas GAP45 is phosphorylated at two sites, one of which could also be detected in phosphopeptides purified from parasite lysates. Both CDPK1 activity and host cell invasion can be inhibited by the kinase inhibitor K252a, suggesting that CDPK1 is a suitable target for antimalarial drug development. PMID:18768477

  8. An integrated model of Plasmodium falciparum dynamics.

    PubMed

    McKenzie, F Ellis; Bossert, William H

    2005-02-07

    The within-host and between-host dynamics of malaria are linked in myriad ways, but most obviously by gametocytes, the parasite blood forms transmissible from human to mosquito. Gametocyte dynamics depend on those of non-transmissible blood forms, which stimulate immune responses, impeding transmission as well as within-host parasite densities. These dynamics can, in turn, influence antigenic diversity and recombination between genetically distinct parasites. Here, we embed a differential-equation model of parasite-immune system interactions within each of the individual humans represented in a discrete-event model of Plasmodium falciparum transmission, and examine the effects of human population turnover, parasite antigenic diversity, recombination, and gametocyte production on the dynamics of malaria. Our results indicate that the local persistence of P. falciparum increases with turnover in the human population and antigenic diversity in the parasite, particularly in combination, and that antigenic diversity arising from meiotic recombination in the parasite has complex differential effects on the persistence of founder and progeny genotypes. We also find that reductions in the duration of individual human infectivity to mosquitoes, even if universal, produce population-level effects only if near-absolute, and that, in competition, the persistence and prevalence of parasite genotypes with gametocyte production concordant with data exceed those of genotypes with higher gametocyte production. This new, integrated approach provides a framework for investigating relationships between pathogen dynamics within an individual host and pathogen dynamics within interacting host and vector populations.

  9. Activity of selected phytochemicals against Plasmodium falciparum.

    PubMed

    Astelbauer, Florian; Gruber, Maria; Brem, Brigitte; Greger, Harald; Obwaller, Andreas; Wernsdorfer, Gunther; Congpuong, Kanungnit; Wernsdorfer, Walther H; Walochnik, Julia

    2012-08-01

    According to the WHO, in 2008, there were 247 million reported cases of malaria and nearly one million deaths from the disease. Parasite resistance against first-line drugs, including artemisinin and mefloquine, is increasing. In this study the plant-derived compounds aglafolin, rocaglamid, kokusaginine, arborine, arborinine and tuberostemonine were investigated for their anti-plasmodial activity in vitro. Fresh Plasmodium falciparum isolates were taken from patients in the area of Mae Sot, north-western Thailand in 2008 and the inhibition of schizont maturation was determined for the respective compounds. With inhibitory concentrations effecting 50%, 90% and 99% inhibition (IC(50), IC(90) and IC(99)) of 60.95 nM, 854.41 nM and 7351.49 nM, respectively, rocaglamid was the most active of the substances, closely followed by aglafoline with 53.49 nM, 864.55 nM and 8354.20 nM. The activity was significantly below that of artemisinin, but moderately higher than that of quinine. Arborine, arborinine, tuberostemonine and kokusaginine showed only marginal activity against P. falciparum characterized by IC(50) and IC(99) values higher than 350 nM and 180 μM, respectively, and regressions with relatively shallow slopes S>14.38. Analogues of rocaglamid and aglafoline merit further exploration of their anti-plasmodial activity.

  10. Induction of gene amplification in Plasmodium falciparum

    SciTech Connect

    Rogers, P.L.

    1985-01-01

    Human erythrocytic in vitro cultures of Honduras I strain of the malaria parasite Plasmodium falciparum have been stressed stepwise with increasing concentrations of methotrexate (MTX), a folate antagonist. This selection has produced a strain that is 450 times more resistant to the drug than the original culture. Uptake of sublethal doses of radiolabeled MTX by infected red blood cells was 6-36 times greater in the resistant cultures than in the nonresistant controls. DNA isolated from all of the parasites was probed by hybridization with /sup 35/S-labeled DNA derived from a clone of the yeast thymidylate synthetase (TS) gene. This showed 50 to 100 times more increased hybridization of the TS probe to the DNA from the resistant parasites is direct evidence of gene amplification because DHFR and TS are actually one and the same bifunctional enzyme in P. falciparum. Hence, the evidence presented indicates that induced resistance of the malaria parasite to MTX in this case is due to overproduction of DHFR resulting from amplification of the DHFR-TS gene.

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

    PubMed

    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.

  12. Immunoglobulin A nephropathy associated with Plasmodium falciparum malaria.

    PubMed

    Yoo, Dong Eun; Kim, Jeong Ho; Kie, Jeong Hae; Park, Yoonseon; Chang, Tae Ik; Oh, Hyung Jung; Kim, Seung Jun; Yoo, Tae-Hyun; Choi, Kyu Hun; Kang, Shin-Wook; Han, Seung Hyeok

    2012-04-01

    Glomerulonephritis occurs as a rare form of renal manifestation in Plasmodium falciparum malaria. Herein, we report a case of falciparum malaria-associated IgA nephropathy for the first time. A 49-yr old male who had been to East Africa was diagnosed with Plasmodium falciparum malaria. Microhematuria and proteinuria along with acute kidney injury developed during the course of the disease. Kidney biopsy showed mesangial proliferation and IgA deposits with tubulointerstitial inflammation. Laboratory tests after recovery from malaria showed disappearance of urinary abnormalities and normalization of kidney function. Our findings suggest that malaria infection might be associated with IgA nephropathy.

  13. Combating multidrug-resistant Plasmodium falciparum malaria.

    PubMed

    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.

  14. Exploring the folate pathway in Plasmodium falciparum.

    PubMed

    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.

  15. Renal pathology in owl monkeys in Plasmodium falciparum vaccine trials.

    PubMed

    Iseki, M; Broderson, J R; Pirl, K G; Igarashi, I; Collins, W E; Aikawa, M

    1990-08-01

    Renal specimens of 16 owl monkeys (Aotus vociferans) were studied by light microscopy and immunohistochemistry during a vaccine trial with recombinant proteins of the ring-infected erythrocyte surface antigen (RESA) of Plasmodium falciparum. Deposition of IgG, C3, and P. falciparum antigens in the mesangium was demonstrated by the peroxidase anti-peroxidase (PAP) method. A relationship between the severity of parasitemia at the time of death and the presence of nephropathy was not apparent.

  16. Evidence for differences in erythrocyte surface receptors for the malarial parasites, Plasmodium falciparum and Plasmodium knowlesi

    PubMed Central

    1977-01-01

    Human erythrocytes lacking various blood group determinants were susceptible to invasion by Plasmodium falciparum including Duffy- negative erythrocytes that are refractory to invasion by Plasmodium knowlesi. Erythrocytes treated with trypsin or neuraminidase had reduced susceptibility of P. falciparum and normal susceptibility to P. knowlesi. Chymotrypsin treatment (0.1 mg/ml) blocked invasion only by P. knowlesi. The differential effect of enzymatic cleavage of determinats from the erythrocyte surface on invasion by these parasites suggests that P. falciparum and P. knowlesi interact with different determinants on the erythrocyte surface. PMID:327014

  17. Drug Evaluation in the Plasmodium Falciparum - Aotus Model

    DTIC Science & Technology

    1993-03-23

    Rossan, RN, Harper, JS III, Davidson, DE Jr., Escajadillo , A. and Christensen, HA.1985. Comparison of Plasmodium falc1parum infections in Panamanian and...Malaria. Amsterdam. 6. Pollack, S, Rossan, RN, Davidson, DE, Escajadillo , A., 1987. Desferrioxamine suppresses Plasmodium falciparum in Aotus monkeys. Proc...Soc Expt Biol Med. 184:162-164.- 7. Panton, LJ, Rossan, RN, Escajadillo , A, Matsumoto, Y, Lee, AT, Labroo, VM, Kirk, KL, Cohen, LA, Airkawa, M, Howard

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

    PubMed Central

    Azevedo, Mauro F; del Portillo, Hernando A

    2007-01-01

    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. PMID:17313673

  19. Artemisinin-resistant Plasmodium falciparum malaria

    PubMed Central

    Fairhurst, Rick M.; Dondorp, Arjen M.

    2016-01-01

    For more than five decades, Southeast Asia (SEA) has been fertile ground for the emergence of drug-resistant Plasmodium falciparum malaria. After generating parasites resistant to chloroquine, sulfadoxine, pyrimethamine, quinine, and mefloquine, this region has now spawned parasites resistant to artemisinins – the world's most potent antimalarial drugs. In areas where artemisinin resistance is prevalent, artemisinin combination therapies (ACTs) – the first-line treatments for malaria – are failing fast. This worrisome development threatens to make malaria practically untreatable in SEA, and threatens to compromise global endeavors to eliminate this disease. A recent series of clinical, in-vitro, genomics, and transcriptomics studies in SEA have defined in-vivo and in-vitro phenotypes of artemisinin resistance; identified its causal genetic determinant; explored its molecular mechanism; and assessed its clinical impact. Specifically, these studies have established that artemisinin resistance manifests as slow parasite clearance in patients and increased survival of early ring-stage parasites in vitro; is caused by single nucleotide polymorphisms in the parasite's ‘K13’ gene; is associated with an upregulated “unfolded protein response” pathway that may antagonize the pro-oxidant activity of artemisinins; and selects for partner drug resistance that rapidly leads to ACT failures. In SEA, clinical studies are urgently needed to monitor ACT efficacy where K13 mutations are prevalent; test whether new combinations of currently-available drugs cure ACT failures; and advance new antimalarial compounds through preclinical pipelines and into clinical trials. Intensifying these efforts should help to forestall the spread of artemisinin and partner drug resistance from SEA to Sub-Saharan Africa, where the world's malaria transmission, morbidity, and mortality rates are highest. PMID:27337450

  20. Artemisinin-Resistant Plasmodium falciparum Malaria.

    PubMed

    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.

  1. Unique properties of Plasmodium falciparum porphobilinogen deaminase.

    PubMed

    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.

  2. Plasmodium falciparum glutaredoxin-like proteins.

    PubMed

    Deponte, Marcel; Becker, Katja; Rahlfs, Stefan

    2005-01-01

    Glutaredoxin-like proteins form a new subgroup of glutaredoxins with a serine replacing the second cysteine in the CxxC-motif of the active site. Yeast Grx5 is the only glutaredoxin-like protein studied biochemically so far. We identified and cloned three genes encoding glutaredoxin-like proteins from the malaria parasite Plasmodium falciparum (Pf Glp1, Pf Glp2, and Pf Glp3) containing a conserved cysteine in the CGFS-, CKFS-, and CKYS-motif, respectively. Here, we describe biochemical properties of Pf Glp1 and Pf Glp2. Cys 99, the only cysteine residue in Pf Glp1, has a pK(a) value as low as 5.5 and is able to mediate covalent homodimerization. Monomeric and dimeric Pf Glp1 react with GSSG and GSH, respectively. Pf Glp2 is monomeric and both of its cysteine residues can be glutathionylated. Molecular models reveal a thioredoxin fold for the putative C-terminal domain of Pf Glp1, Pf Glp2, and Pf Glp3, as well as conserved residues presumably required for glutathione binding. However, Pf Glp1 and Pf Glp2 neither possess activity in a classical glutaredoxin assay nor display activity as glutathione peroxidase or glutathione S-transferase. Mutation of Ser 102 in the CGFS-motif of Pf Glp1 to cysteine did not generate glutaredoxin activity either. We conclude that, despite their ability to react with glutathione, glutaredoxin-like proteins are a mechanistically and functionally heterogeneous group with only little similarities to canonical glutaredoxins.

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

    PubMed

    Zerka, Agata; Kaczmarek, Radosław; Jaśkiewicz, Ewa

    2015-12-31

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

  4. Primaquine for reducing Plasmodium falciparum transmission.

    PubMed

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

    2012-09-12

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

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

    PubMed Central

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

    2010-01-01

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

  6. Drug Evaluation in the Plasmodium falciparum - Aotus Model

    DTIC Science & Technology

    1984-09-01

    R. N., Harper, J. S. Ill, Davidson D. E. Jr., Escajadillo , A. and Christensen H. A. Comparison of Plasmodium falciparum infec- tions in Panamanian...CONTRACTS R. N. Rossan, Ph. D. D. C. Baerg, Ph. D. J. C. Harper, VMD A. Escajadillo , DVM H. A. Christensen, Ph. D L. Martinez F. Durham G. Ci

  7. New Strategies for Drug Discovery and Development for Plasmodium falciparum

    DTIC Science & Technology

    2001-01-01

    research working in concert with one another. The goal of this work is to use a molecular genetic approach both in the identification of new drug targets and...Plasmodium falciparum for their role in drug resistance and as potential new drug targets, including the analysis of gene expression in response to

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

    PubMed Central

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

    2008-01-01

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

  9. Mitosis in the Human Malaria Parasite Plasmodium falciparum

    PubMed Central

    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

  10. Endemicity response timelines for Plasmodium falciparum elimination.

    PubMed

    Smith, David L; Hay, Simon I

    2009-04-30

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

  11. Minireview: Invasive fungal infection complicating acute Plasmodium falciparum malaria.

    PubMed

    Däbritz, Jan; Schneider, Markward; Just-Nuebling, Gudrun; Groll, Andreas H

    2011-07-01

    Malaria is the most important parasitic infection in people, affecting 5-10% of the world's population with more than two million deaths a year. Whereas invasive bacterial infections are not uncommon during severe Plasmodium falciparum malaria, only a few cases of opportunistic fungal infections have been reported. Here, we present a fatal case of disseminated hyalohyphomycosis associated with acute P. falciparum malaria in a non-immune traveller, review the cases reported in the literature and discuss the theoretical foundations for the increased susceptibility of non-immune individuals with severe P. falciparum malaria to opportunistic fungal infections. Apart from the availability of free iron as sequelae of massive haemolysis, tissue damage, acidosis and measures of advanced life support, patients with complicated P. falciparum malaria also are profoundly immunosuppressed by the organism's interaction with innate and adaptive host immune mechanisms.

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

    PubMed Central

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

    PubMed Central

    MASON, DANIEL P.; McKENZIE, F. ELLIS

    2008-01-01

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

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

    DTIC Science & Technology

    2013-01-02

    molecular markers Artemisinin-based combination therapies (ACTs) are the lead-ing treatment for Plasmodium falciparum malaria (1), and their use with... Plasmodium falciparum malaria . N Engl J Med 361(5):455–467. 8. Noedl H, et al.; Artemisinin Resistance in Cambodia 1 (ARC1) Study Consortium (2008...Genetic loci associated with delayed clearance of Plasmodium falciparum following artemisinin treatment in Southeast Asia Shannon Takala-Harrisona

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

    DTIC Science & Technology

    2007-11-02

    AD Award Number: DAMDl7-01-C-0039 TITLE: Drug and Vaccine Evaluation in the Human Aotus Plasmodium Falciparum Model PRINCIPAL INVESTIGATOR: Nicanor... Human Aotus DAMDI7-01-C-0039 Plasmodium Falciparum Model 6. AUTHOR(S): Nicanor Obaldia, III, D.V.M. 7. PERFORMING ORGANIZATION NAME(S) AND ADDRESS(ES) 8...evaluation of drugs and vaccines in the human malarialAotus lemurinus lemurinus monkey model experimientally infected with Plasmodium falciparum or vivax

  16. Simple Molecular Methods for Early Detection of Chloroquine Drug Resistance in Plasmodium vivax and Plasmodium falciparum.

    PubMed

    Singh, Gurjeet; Singh, Raksha; Urhehar, Anant Dattatraya

    2016-07-01

    Malaria is a human disease of which causes high morbidity and mortality. In Plasmodium falciparum malaria, the resistance to antimalarial drugs, especially chloroquine (CQ) is one of the paramount factors contributing to the global increase in morbidity and mortality, due to malaria. Hence, there is a need for detection of chloroquine drug resistance genes i.e., pfcrt-o (Plasmodium falciparum chloroquine resistance transporter-o) and pfmdr-1 (Plasmodium falciparum multidrug resistance-1) of P. falciparum and pvcrt-o (Plasmodium vivax chloroquine resistance transporter-o) and pvmdr-1 (Plasmodium vivax multidrug resistance-1) of P. vivax by using molecular methods to prevent mortality in malarial cases. To standardize chloroquine drug sensitivity testing by molecular method so as to provide reports of chloroquine within 6-8 hours to physicians for better treatment. This study was conducted over a period of one year from January to December 2014. A Total of 300 blood samples were collected from malaria suspected patient attending MGM Hospital, Kamothe, Navi Mumbai, India. Out of 300 blood samples, 44 were malaria positive as assessed by Thick and Thin blood smear stained, by Leishman's method and examination with light microscope. Chloroquine drug sensitivity testing was performed using WHO III plate method (micro test). Nested PCR was done for detection of pfcrt-o and pfmdr-1 for P. falciparum and pvcrt-o, pvmdr-1 genes for P. vivax. Total 44 samples were included in this study, out of which 22 samples confirmed for Plasmodium falciparum and 22 samples confirmed for Plasmodium vivax. Out of 22 P. falciparum 15 (68.18%) samples were chloroquine resistant. P. vivax showed chloroquine resistance to 5 samples (22.73%) by method similar to WHO III plate method (micro test) and nested PCR. Drug resistance testing by molecular methods is useful for early detection of antimalarial drug resistance. pfmdr-1 along with pfcrt-o can be used as biomarker for chloroquine drug

  17. Replication and maintenance of the Plasmodium falciparum apicoplast genome.

    PubMed

    Milton, Morgan E; Nelson, Scott W

    2016-08-01

    Members of the phylum Apicomplexa are responsible for many devastating diseases including malaria (Plasmodium spp.), toxoplasmosis (Toxoplasma gondii), babesiosis (Babesia bovis), and cyclosporiasis (Cyclospora cayetanensis). Most Apicomplexans contain a unique and essential organelle called the apicoplast. Derived from an ancient chloroplast, the apicoplast replicates and maintains a 35 kilobase (kb) circular genome. Due to its essential nature within the parasite, drugs targeted to proteins involved in DNA replication and repair of the apicoplast should be potent and specific. This review summarizes the current knowledge surrounding the replication and repair of the Plasmodium falciparum apicoplast genome and identifies several putative proteins involved in replication and repair pathways.

  18. Antifolate Agents Against Wild and Mutant Strains of Plasmodium falciparum

    PubMed Central

    Shaikh, M. S.; Rana, J.; Gaikwad, D.; Leartsakulpanich, U.; Ambre, Premlata K.; Pissurlenkar, R. R. S.; Coutinho, E. C.

    2014-01-01

    Plasmodium falciparum dihydrofolate reductase is an important target for antimalarial chemotherapy. The emergence of resistance has significantly reduced the efficacy of the classic antifolate drugs cycloguanil and pyrimethamine. In this paper we report new dihydrofolate reductase inhibitors identified using molecular modelling principles with the goal of designing new antifolate agents active against both wild and tetramutant dihydrofolate reductase strains three series of trimethoprim analogues were designed, synthesised and tested for biological activity. Pyrimethamine and cycloguanil have been reported to loose efficacy because of steric repulsion in the active site pocket produced due to mutation in Plasmodium falciparum dihydrofolate reductase. The synthesised molecules have sufficient flexibility to withstand this steric repulsion to counteract the resistance. The molecules have been synthesised by conventional techniques and fully characterised by spectroscopic methods. The potency of these molecules was evaluated by in vitro enzyme specific assays. Some of the molecules were active in micromolar concentrations and can easily be optimised to improve binding and activity. PMID:24843184

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

    PubMed Central

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

    2012-01-01

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

  20. Plasmodium falciparum Malaria: reduction of endothelial cell apoptosis in vitro.

    PubMed

    Hemmer, Christoph Josef; Lehr, Hans Anton; Westphal, Kathi; Unverricht, Marcus; Kratzius, Manja; Reisinger, Emil Christian

    2005-03-01

    Organ failure in Plasmodium falciparum malaria is associated with neutrophil activation and endothelial damage. This study investigates whether neutrophil-induced endothelial damage involves apoptosis and whether it can be prevented by neutralization of neutrophil secretory products. Endothelial cells from human umbilical veins were coincubated with neutrophils from healthy donors and with sera from eight patients with P. falciparum malaria, three patients with P. vivax malaria, and three healthy controls. Endothelial apoptosis was demonstrated by terminal deoxynucleotidyltransferase-mediated dUTP-biotin nick end labeling (TUNEL) and annexin V staining. The rate of apoptosis of cells was markedly increased after incubation with patient serum compared to that with control serum. Apoptosis was most pronounced after incubation with sera from two patients with fatal cases of P. falciparum malaria, followed by sera of survivors with severe P. falciparum malaria and, finally, by sera of patients with mild P. falciparum and P. vivax malaria. Ascorbic acid, tocopherol, and ulinastatin reduced the apoptosis rate, but gabexate mesilate and pentoxifylline did not. Furthermore, in fatal P. falciparum malaria, apoptotic endothelial cells were identified in renal and pulmonary tissue by TUNEL staining. These findings show that apoptosis caused by neutrophil secretory products plays a major role in endothelial cell damage in malaria. The antioxidants ascorbic acid and tocopherol and the protease inhibitor ulinastatin can reduce malaria-associated endothelial apoptosis in vitro.

  1. In silico comparative genome analysis of malaria parasite Plasmodium falciparum and Plasmodium vivax chromosome 4.

    PubMed

    Taherian Fard, Atefeh; Salman, Amna; Kazemi, Bahram; Bokhari, Habib

    2009-06-01

    Malarial parasite has long been a subject of research for a large community of scientists and has yet to be conquered. One of the main obstacles to effectively control this disease is rapidly evolving genetic structure of Plasmodium parasite itself. In this study, we focused on chromosome 4 of the Plasmodium falciparum and Plasmodium vivax species and carried out comparative studies of genes that are responsible for antigenic variation in respective species. Comparative analysis of genes responsible for antigenic variation (var and vir genes in P. falciparum and P. vivax, respectively) showed significant difference in their respective nucleotide sequence lengths as well as amino acid composition. The possible association of exon's length on pathogenecity of respective Plasmodium species was also investigated, and analysis of gene structure showed that on the whole, exon lengths in P. falciparum are larger compared to P. vivax. Analysis of tandem repeats across the genome has shown that the size of repetitive sequences has a direct effect on chromosomes length, which can also be a potential reason for P. falciparum's greater variability and hence pathogenecity than P. vivax.

  2. Drug Evaluation in the Plasmodium Falciparum - Aotus Model

    DTIC Science & Technology

    1994-03-15

    chloroquine, quinine, and pyrimethamine. Am J Trop Med Hyg 27:703-717. 3. Rossan, RN, Harper, JS III, Davidson, DE Jr., Escajadillo , A. and...primaquine. Presented at XII International Congress for Tropical Medicine and Malaria. Amsterdam. 6, Pollack, S, Rossan, RN, Davidson, DE, Escajadillo , A...1987. Desferrioxamine suppresses Plasmodium falciparum in Aotus monkeys. Proc Soc Expt Biol Med. 184-162-164. 7. Panton, LJ, Rossan, RN, Escajadillo

  3. Plasmodium falciparum genetic crosses in a humanized mouse model

    PubMed Central

    Vaughan, Ashley M.; Pinapati, Richard S.; Cheeseman, Ian H.; Camargo, Nelly; Fishbaugher, Matthew; Checkley, Lisa A.; Nair, Shalini; Hutyra, Carolyn A.; Nosten, François H.; Anderson, Timothy J. C.; Ferdig, Michael T.; Kappe, Stefan H. I.

    2015-01-01

    Genetic crosses of phenotypically distinct strains of the human malaria parasite Plasmodium falciparum are a powerful tool for identifying genes controlling drug resistance and other key phenotypes. Previous studies relied on the isolation of recombinant parasites from splenectomized chimpanzees, a research avenue that is no longer available. Here, we demonstrate that human-liver chimeric mice support recovery of recombinant progeny for the identification of genetic determinants of parasite traits and adaptations. PMID:26030447

  4. Fate of haem iron in the malaria parasite Plasmodium falciparum.

    PubMed Central

    Egan, Timothy J; Combrinck, Jill M; Egan, Joanne; Hearne, Giovanni R; Marques, Helder M; Ntenteni, Skhumbuzo; Sewell, B Trevor; Smith, Peter J; Taylor, Dale; van Schalkwyk, Donelly A; Walden, Jason C

    2002-01-01

    Chemical analysis has shown that Plasmodium falciparum trophozoites contain 61+/-2% of the iron within parasitized erythrocytes, of which 92+/-6% is located within the food vacuole. Of this, 88+/-9% is in the form of haemozoin. (57)Fe-Mössbauer spectroscopy shows that haemozoin is the only detectable iron species in trophozoites. Electron spectroscopic imaging confirms this conclusion. PMID:12033986

  5. Structure of Plasmodium falciparum ADP-ribosylation factor 1

    PubMed Central

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

    2010-01-01

    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 Å resolution and is compared with the structures of mammalian ARF1s. PMID:21045287

  6. Sensitive and specific DNA probe for detection of Plasmodium falciparum.

    PubMed Central

    Enea, V

    1986-01-01

    The isolation and some characteristics of a very sensitive DNA probe for the detection of Plasmodium falciparum are described. The probe is species specific and represents a large, albeit variable, fraction of the genome in all the strains tested. In addition to its immediate practical uses for the detection and quantitation of parasites, the probe defines an interesting family of repeated sequences. Images PMID:3023833

  7. Killing of Plasmodium falciparum in vitro by nitric oxide derivatives.

    PubMed Central

    Rockett, K A; Awburn, M M; Cowden, W B; Clark, I A

    1991-01-01

    We have investigated the in vitro susceptibility of the human malaria parasite Plasmodium falciparum to killing by nitric oxide and related molecules. A saturated solution of nitric oxide did not inhibit parasite growth, but two oxidation products of nitric oxide (nitrite and nitrate ions) were toxic to the parasite in millimolar concentrations. Nitrosothiol derivatives of cysteine and glutathione were found to be about a thousand times more active (50% growth inhibitory concentration, approximately 40 microM) than nitrite. PMID:1879941

  8. Structure of Plasmodium falciparum ADP-ribosylation factor 1

    SciTech Connect

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

    2011-09-26

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

  9. Biochemical and functional characterization of Plasmodium falciparum GTP cyclohydrolase I

    PubMed Central

    2014-01-01

    Background Antifolates are currently in clinical use for malaria preventive therapy and treatment. The drugs kill the parasites by targeting the enzymes in the de novo folate pathway. The use of antifolates has now been limited by the spread of drug-resistant mutations. GTP cyclohydrolase I (GCH1) is the first and the rate-limiting enzyme in the folate pathway. The amplification of the gch1 gene found in certain Plasmodium falciparum isolates can cause antifolate resistance and influence the course of antifolate resistance evolution. These findings showed the importance of P. falciparum GCH1 in drug resistance intervention. However, little is known about P. falciparum GCH1 in terms of kinetic parameters and functional assays, precluding the opportunity to obtain the key information on its catalytic reaction and to eventually develop this enzyme as a drug target. Methods Plasmodium falciparum GCH1 was cloned and expressed in bacteria. Enzymatic activity was determined by the measurement of fluorescent converted neopterin with assay validation by using mutant and GTP analogue. The genetic complementation study was performed in ∆folE bacteria to functionally identify the residues and domains of P. falciparum GCH1 required for its enzymatic activity. Plasmodial GCH1 sequences were aligned and structurally modeled to reveal conserved catalytic residues. Results Kinetic parameters and optimal conditions for enzymatic reactions were determined by the fluorescence-based assay. The inhibitor test against P. falciparum GCH1 is now possible as indicated by the inhibitory effect by 8-oxo-GTP. Genetic complementation was proven to be a convenient method to study the function of P. falciparum GCH1. A series of domain truncations revealed that the conserved core domain of GCH1 is responsible for its enzymatic activity. Homology modelling fits P. falciparum GCH1 into the classic Tunnelling-fold structure with well-conserved catalytic residues at the active site. Conclusions

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

    PubMed

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

    2008-11-01

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

  11. Multiple independent introductions of Plasmodium falciparum in South America

    PubMed Central

    Yalcindag, Erhan; Elguero, Eric; Arnathau, Céline; Durand, Patrick; Akiana, Jean; Anderson, Timothy J.; Aubouy, Agnes; Balloux, François; Besnard, Patrick; Bogreau, Hervé; Carnevale, Pierre; D'Alessandro, Umberto; Fontenille, Didier; Gamboa, Dionicia; Jombart, Thibaut; Le Mire, Jacques; Leroy, Eric; Maestre, Amanda; Mayxay, Mayfong; Ménard, Didier; Musset, Lise; Newton, Paul N.; Nkoghé, Dieudonné; Noya, Oscar; Ollomo, Benjamin; Rogier, Christophe; Veron, Vincent; Wide, Albina; Zakeri, Sedigheh; Carme, Bernard; Legrand, Eric; Chevillon, Christine; Ayala, Francisco J.; Renaud, François; Prugnolle, Franck

    2012-01-01

    The origin of Plasmodium falciparum in South America is controversial. Some studies suggest a recent introduction during the European colonizations and the transatlantic slave trade. Other evidence—archeological and genetic—suggests a much older origin. We collected and analyzed P. falciparum isolates from different regions of the world, encompassing the distribution range of the parasite, including populations from sub-Saharan Africa, the Middle East, Southeast Asia, and South America. Analyses of microsatellite and SNP polymorphisms show that the populations of P. falciparum in South America are subdivided in two main genetic clusters (northern and southern). Phylogenetic analyses, as well as Approximate Bayesian Computation methods suggest independent introductions of the two clusters from African sources. Our estimates of divergence time between the South American populations and their likely sources favor a likely introduction from Africa during the transatlantic slave trade. PMID:22203975

  12. Identification and localization of a Novel Invasin of Plasmodium falciparum.

    PubMed

    Hans, Nidhi; Relan, Udbhav; Dubey, Nneha; Gaur, Deepak; Chauhan, V S

    2015-08-01

    Plasmodium falciparum is the causative organism for the most severe form of malaria among humans. The clinical symptoms are accredited to the asexual stage of parasite life cycle, involving merozoite invasion of erythrocyte, development and re-invasion into the new erythrocyte. Interaction of parasite proteins present on the surface or secreted from apical organelles with the host receptors is indispensable for the invasion process. Identification and elucidation of precise localization and function of these proteins will not only enhance our understanding of this process but will also aid in the progress of development of treatment strategies against malaria. Here we report the identification and localization of a novel protein, PfAEP (P. falciparum Apical Exonemal Protein) (PF3D7_1137200/ PF11_0383) which is conserved across Plasmodium species. Transcription and translation analysis have confirmed its expression in the schizont stage of P. falciparum. Super-resolution microscopy in schizonts and merozoites revealed its localization in the exonemes of P. falciparum.

  13. Carotenoid Biosynthesis in Intraerythrocytic Stages of Plasmodium falciparum*S⃞

    PubMed Central

    Tonhosolo, Renata; D'Alexandri, Fabio L.; de Rosso, Veridiana V.; Gazarini, Marcos L.; Matsumura, Miriam Y.; Peres, Valnice J.; Merino, Emilio F.; Carlton, Jane M.; Wunderlich, Gerhard; Mercadante, Adriana Z.; Kimura, Emília A.; Katzin, Alejandro M.

    2009-01-01

    Carotenoids are widespread lipophilic pigments synthesized by all photosynthetic organisms and some nonphotosynthetic fungi and bacteria. All carotenoids are derived from the C40 isoprenoid precursor geranylgeranyl pyrophosphate, and their chemical and physical properties are associated with light absorption, free radical scavenging, and antioxidant activity. Carotenoids are generally synthesized in well defined subcellular organelles, the plastids, which are also present in the phylum Apicomplexa, which comprises a number of important human parasites, such as Plasmodium and Toxoplasma. Recently, it was demonstrated that Toxoplasma gondii synthesizes abscisic acid. We therefore asked if Plasmodium falciparum is also capable of synthesizing carotenoids. Herein, biochemical findings demonstrated the presence of carotenoid biosynthesis in the intraerythrocytic stages of the apicomplexan parasite P. falciparum. Using metabolic labeling with radioisotopes, in vitro inhibition tests with norflurazon, a specific inhibitor of plant carotenoid biosynthesis, the results showed that intraerythrocytic stages of P. falciparum synthesize carotenoid compounds. A plasmodial enzyme that presented phytoene synthase activity was also identified and characterized. These findings not only contribute to the current understanding of P. falciparum evolution but shed light on a pathway that could serve as a chemotherapeutic target. PMID:19203994

  14. Low-Complexity Regions in Plasmodium falciparum Proteins

    PubMed Central

    Pizzi, Elisabetta; Frontali, Clara

    2001-01-01

    Full-sequence data available for Plasmodium falciparum chromosomes 2 and 3 are exploited to perform a statistical analysis of the long tracts of biased amino acid composition that characterize the vast majority of P. falciparum proteins and to make a comparison with similarly defined tracts from other simple eukaryotes. When the relatively minor subset of prevalently hydrophobic segments is discarded from the set of low-complexity segments identified by current segmentation methods in P. falciparum proteins, a good correspondence is found between prevalently hydrophilic low-complexity segments and the species-specific, rapidly diverging insertions detected by multiple-alignment procedures when sequences of bona fide homologs are available. Amino acid preferences are fairly uniform in the set of hydrophilic low-complexity segments identified in the two P. falciparum chromosomes sequenced, as well as in sequenced genes from Plasmodium berghei, but differ from those observed in Saccharomyces cerevisiae and Dictyostelium discoideum. In the two plasmodial species, amino acid frequencies do not correlate with properties such as hydrophilicity, small volume, or flexibility, which might be expected to characterize residues involved in nonglobular domains but do correlate with A-richness in codons. An effect of phenotypic selection versus neutral drift, however, is suggested by the predominance of asparagine over lysine. PMID:11157785

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

    PubMed

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

    2011-12-19

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

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

    PubMed Central

    2011-01-01

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

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

    PubMed

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

    2013-01-01

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

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

    PubMed Central

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

    2013-01-01

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

  19. Ex Vivo Activity of Endoperoxide Antimalarials, Including Artemisone and Arterolane, against Multidrug-Resistant Plasmodium falciparum Isolates from Cambodia

    DTIC Science & Technology

    2014-10-01

    of artemisinin combination therapies (ACTs) to treat artemisinin-resistant Plasmodium falciparum malaria . We conducted blinded ex vivo activity...Optimizing the HRP-2 in vitro malaria drug susceptibility assay using a reference clone to improve comparisons of Plasmodium falciparum field isolates... malaria SYBR green I fluorescence (MSF) drug sensitivity tests in Plasmodium falciparum refer- ence clones and fresh ex vivo field isolates from

  20. Characterization of Plasmodium falciparum Choline Transporters

    DTIC Science & Technology

    2005-04-01

    interfere specifically with parasite membrane biogenesis inhibit the growth of the parasite in vitro, are non-toxic to human cell lines, impair the...phosphocholine. Collectively, our data supported by the USAMRMC provide a much better understanding of membrane biogenesis in P. falciparum and provide strong...characterize the role of the PJSCT1 (now renamed PfGAT) and PfCTL1 genes of the human malaria pathogen Plasmodiumfalciparum in membrane biogenesis

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

    PubMed

    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.

  2. Plasmodium falciparum accompanied the human expansion out of Africa.

    PubMed

    Tanabe, Kazuyuki; Mita, Toshihiro; Jombart, Thibaut; Eriksson, Anders; Horibe, Shun; Palacpac, Nirianne; Ranford-Cartwright, Lisa; Sawai, Hiromi; Sakihama, Naoko; Ohmae, Hiroshi; Nakamura, Masatoshi; Ferreira, Marcelo U; Escalante, Ananias A; Prugnolle, Franck; Björkman, Anders; Färnert, Anna; Kaneko, Akira; Horii, Toshihiro; Manica, Andrea; Kishino, Hirohisa; Balloux, Francois

    2010-07-27

    Plasmodium falciparum is distributed throughout the tropics and is responsible for an estimated 230 million cases of malaria every year, with a further 1.4 billion people at risk of infection. Little is known about the genetic makeup of P. falciparum populations, despite variation in genetic diversity being a key factor in morbidity, mortality, and the success of malaria control initiatives. Here we analyze a worldwide sample of 519 P. falciparum isolates sequenced for two housekeeping genes (63 single nucleotide polymorphisms from around 5000 nucleotides per isolate). We observe a strong negative correlation between within-population genetic diversity and geographic distance from sub-Saharan Africa (R(2) = 0.95) over Africa, Asia, and Oceania. In contrast, regional variation in transmission intensity seems to have had a negligible impact on the distribution of genetic diversity. The striking geographic patterns of isolation by distance observed in P. falciparum mirror the ones previously documented in humans and point to a joint sub-Saharan African origin between the parasite and its host. Age estimates for the expansion of P. falciparum further support that anatomically modern humans were infected prior to their exit out of Africa and carried the parasite along during their colonization of the world. 2010 Elsevier Ltd. All rights reserved.

  3. A systematic map of genetic variation in Plasmodium falciparum.

    PubMed

    Kidgell, Claire; Volkman, Sarah K; Daily, Johanna; Borevitz, Justin O; Plouffe, David; Zhou, Yingyao; Johnson, Jeffrey R; Le Roch, Karine; Sarr, Ousmane; Ndir, Omar; Mboup, Soulyemane; Batalov, Serge; Wirth, Dyann F; Winzeler, Elizabeth A

    2006-06-01

    Discovering novel genes involved in immune evasion and drug resistance in the human malaria parasite, Plasmodium falciparum, is of critical importance to global health. Such knowledge may assist in the development of new effective vaccines and in the appropriate use of antimalarial drugs. By performing a full-genome scan of allelic variability in 14 field and laboratory strains of P. falciparum, we comprehensively identified approximately 500 genes evolving at higher than neutral rates. The majority of the most variable genes have paralogs within the P. falciparum genome and may be subject to a different evolutionary clock than those without. The group of 211 variable genes without paralogs contains most known immunogens and a few drug targets, consistent with the idea that the human immune system and drug use is driving parasite evolution. We also reveal gene-amplification events including one surrounding pfmdr1, the P. falciparum multidrug-resistance gene, and a previously uncharacterized amplification centered around the P. falciparum GTP cyclohydrolase gene, the first enzyme in the folate biosynthesis pathway. Although GTP cyclohydrolase is not the known target of any current drugs, downstream members of the pathway are targeted by several widely used antimalarials. We speculate that an amplification of the GTP cyclohydrolase enzyme in the folate biosynthesis pathway may increase flux through this pathway and facilitate parasite resistance to antifolate drugs.

  4. Severe Plasmodium falciparum and Plasmodium vivax malaria among adults at Kassala Hospital, eastern Sudan

    PubMed Central

    2013-01-01

    Background There have been few published reports on severe Plasmodium falciparum and Plasmodium vivax malaria among adults in Africa. Methods Clinical pattern/manifestations of severe P. falciparum and P. vivax (according to World Health Organization 2000 criteria) were described in adult patients admitted to Kassala Hospital, eastern Sudan. Results A total of 139 adult patients (80 males, 57.6%) with a mean (SD) age of 37.2 (1.5) years presented with severe P. falciparum (113, 81.3%) or P. vivax (26, 18.7%) malaria. Manifestations among the 139 patients included hypotension (38, 27.3%), cerebral malaria (23, 16.5%), repeated convulsions (18, 13.0%), hypoglycaemia (15, 10.8%), hyperparasitaemia (14, 10.1%), jaundice (14, 10.1%), severe anaemia (10, 7.2%), bleeding (six, 4.3%), renal impairment (one, 0.7%) and more than one criteria (27, 19.4%). While the geometric mean of the parasite count was significantly higher in patients with severe P. vivax than with severe P. falciparum malaria (5,934.2 vs 13,906.6 asexual stage parasitaemia per μL, p = 0.013), the different disease manifestations were not significantly different between patients with P. falciparum or P. vivax malaria. Three patients (2.2%) died due to severe P. falciparum malaria. One had cerebral malaria, the second had renal impairment, jaundice and hypoglycaemia, and the third had repeated convulsions and hypotension. Conclusions Severe malaria due to P. falciparum and P. vivax malaria is an existing entity among adults in eastern Sudan. Patients with severe P. falciparum and P. vivax develop similar disease manifestations. PMID:23634728

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

    PubMed Central

    2012-01-01

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

  6. Antimalarial Benzoxaboroles Target Plasmodium falciparum Leucyl-tRNA Synthetase

    PubMed Central

    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

    2016-01-01

    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 [14C]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. PMID:27270277

  7. The transcriptome of the intraerythrocytic developmental cycle of Plasmodium falciparum.

    PubMed

    Bozdech, Zbynek; Llinás, Manuel; Pulliam, Brian Lee; Wong, Edith D; Zhu, Jingchun; DeRisi, Joseph L

    2003-10-01

    Plasmodium falciparum is the causative agent of the most burdensome form of human malaria, affecting 200-300 million individuals per year worldwide. The recently sequenced genome of P. falciparum revealed over 5,400 genes, of which 60% encode proteins of unknown function. Insights into the biochemical function and regulation of these genes will provide the foundation for future drug and vaccine development efforts toward eradication of this disease. By analyzing the complete asexual intraerythrocytic developmental cycle (IDC) transcriptome of the HB3 strain of P. falciparum, we demonstrate that at least 60% of the genome is transcriptionally active during this stage. Our data demonstrate that this parasite has evolved an extremely specialized mode of transcriptional regulation that produces a continuous cascade of gene expression, beginning with genes corresponding to general cellular processes, such as protein synthesis, and ending with Plasmodium-specific functionalities, such as genes involved in erythrocyte invasion. The data reveal that genes contiguous along the chromosomes are rarely coregulated, while transcription from the plastid genome is highly coregulated and likely polycistronic. Comparative genomic hybridization between HB3 and the reference genome strain (3D7) was used to distinguish between genes not expressed during the IDC and genes not detected because of possible sequence variations. Genomic differences between these strains were found almost exclusively in the highly antigenic subtelomeric regions of chromosomes. The simple cascade of gene regulation that directs the asexual development of P. falciparum is unprecedented in eukaryotic biology. The transcriptome of the IDC resembles a "just-in-time" manufacturing process whereby induction of any given gene occurs once per cycle and only at a time when it is required. These data provide to our knowledge the first comprehensive view of the timing of transcription throughout the intraerythrocytic

  8. The Transcriptome of the Intraerythrocytic Developmental Cycle of Plasmodium falciparum

    PubMed Central

    Pulliam, Brian Lee; Wong, Edith D; Zhu, Jingchun

    2003-01-01

    Plasmodium falciparum is the causative agent of the most burdensome form of human malaria, affecting 200–300 million individuals per year worldwide. The recently sequenced genome of P. falciparum revealed over 5,400 genes, of which 60% encode proteins of unknown function. Insights into the biochemical function and regulation of these genes will provide the foundation for future drug and vaccine development efforts toward eradication of this disease. By analyzing the complete asexual intraerythrocytic developmental cycle (IDC) transcriptome of the HB3 strain of P. falciparum, we demonstrate that at least 60% of the genome is transcriptionally active during this stage. Our data demonstrate that this parasite has evolved an extremely specialized mode of transcriptional regulation that produces a continuous cascade of gene expression, beginning with genes corresponding to general cellular processes, such as protein synthesis, and ending with Plasmodium-specific functionalities, such as genes involved in erythrocyte invasion. The data reveal that genes contiguous along the chromosomes are rarely coregulated, while transcription from the plastid genome is highly coregulated and likely polycistronic. Comparative genomic hybridization between HB3 and the reference genome strain (3D7) was used to distinguish between genes not expressed during the IDC and genes not detected because of possible sequence variations. Genomic differences between these strains were found almost exclusively in the highly antigenic subtelomeric regions of chromosomes. The simple cascade of gene regulation that directs the asexual development of P. falciparum is unprecedented in eukaryotic biology. The transcriptome of the IDC resembles a “just-in-time” manufacturing process whereby induction of any given gene occurs once per cycle and only at a time when it is required. These data provide to our knowledge the first comprehensive view of the timing of transcription throughout the

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

    PubMed

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

    2016-02-10

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

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

    PubMed Central

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

    2016-01-01

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

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

    PubMed

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

    2014-06-01

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

  12. Gene copy number variation throughout the Plasmodium falciparum genome.

    PubMed

    Cheeseman, Ian H; Gomez-Escobar, Natalia; Carret, Celine K; Ivens, Alasdair; Stewart, Lindsay B; Tetteh, Kevin K A; Conway, David J

    2009-08-04

    Gene copy number variation (CNV) is responsible for several important phenotypes of the malaria parasite Plasmodium falciparum, including drug resistance, loss of infected erythrocyte cytoadherence and alteration of receptor usage for erythrocyte invasion. Despite the known effects of CNV, little is known about its extent throughout the genome. We performed a whole-genome survey of CNV genes in P. falciparum using comparative genome hybridisation of a diverse set of 16 laboratory culture-adapted isolates to a custom designed high density Affymetrix GeneChip array. Overall, 186 genes showed hybridisation signals consistent with deletion or amplification in one or more isolate. There is a strong association of CNV with gene length, genomic location, and low orthology to genes in other Plasmodium species. Sub-telomeric regions of all chromosomes are strongly associated with CNV genes independent from members of previously described multigene families. However, approximately 40% of CNV genes were located in more central regions of the chromosomes. Among the previously undescribed CNV genes, several that are of potential phenotypic relevance are identified. CNV represents a major form of genetic variation within the P. falciparum genome; the distribution of gene features indicates the involvement of highly non-random mutational and selective processes. Additional studies should be directed at examining CNV in natural parasite populations to extend conclusions to clinical settings.

  13. Preerythrocytic, live-attenuated Plasmodium falciparum vaccine candidates by design.

    PubMed

    VanBuskirk, Kelley M; O'Neill, Matthew T; De La Vega, Patricia; Maier, Alexander G; Krzych, Urszula; Williams, Jack; Dowler, Megan G; Sacci, John B; Kangwanrangsan, Niwat; Tsuboi, Takafumi; Kneteman, Norman M; Heppner, Donald G; Murdock, Brant A; Mikolajczak, Sebastian A; Aly, Ahmed S I; Cowman, Alan F; Kappe, Stefan H I

    2009-08-04

    Falciparum malaria is initiated when Anopheles mosquitoes transmit the Plasmodium sporozoite stage during a blood meal. Irradiated sporozoites confer sterile protection against subsequent malaria infection in animal models and humans. This level of protection is unmatched by current recombinant malaria vaccines. However, the live-attenuated vaccine approach faces formidable obstacles, including development of accurate, reproducible attenuation techniques. We tested whether Plasmodium falciparum could be attenuated at the early liver stage by genetic engineering. The P. falciparum genetically attenuated parasites (GAPs) harbor individual deletions or simultaneous deletions of the sporozoite-expressed genes P52 and P36. Gene deletions were done by double-cross-over recombination to avoid genetic reversion of the knockout parasites. The gene deletions did not affect parasite replication throughout the erythrocytic cycle, gametocyte production, mosquito infections, and sporozoite production rates. However, the deletions caused parasite developmental arrest during hepatocyte infection. The double-gene deletion line exhibited a more severe intrahepatocytic growth defect compared with the single-gene deletion lines, and it did not persist. This defect was assessed in an in vitro liver-stage growth assay and in a chimeric mouse model harboring human hepatocytes. The strong phenotype of the double knockout GAP justifies its human testing as a whole-organism vaccine candidate using the established sporozoite challenge model. GAPs might provide a safe and reproducible platform to develop an efficacious whole-cell malaria vaccine that prevents infection at the preerythrocytic stage.

  14. Laser-induced inactivation of Plasmodium falciparum

    PubMed Central

    2012-01-01

    Background Haemozoin crystals, produced by Plasmodium during its intra-erythrocytic asexual reproduction cycle, can generate UV light via the laser-induced, non-linear optical process of third harmonic generation (THG). In the current study the feasibility of using haemozoin, constitutively stored in the parasite’s food vacuole, to kill the parasite by irradiation with a near IR laser was evaluated. Methods Cultured Plasmodium parasites at different stages of development were irradiated with a pulsed NIR laser and the viability of parasites at each stage was evaluated from their corresponding growth curves using the continuous culture method. Additional testing for germicidal effects of haemozoin and NIR laser was performed by adding synthetic haemozoin crystals to Escherichia coli in suspension. Cell suspensions were then irradiated with the laser and small aliquots taken and spread on agar plates containing selective agents to determine cell viability (CFU). Results Parasites in the late-trophozoites form as well as trophozoites in early-stage of DNA synthesis were found to be the most sensitive to the treatment with ~4-log reduction in viability after six passes through the laser beam; followed by parasites in ring phase (~2-log reduction). A ~1-log reduction in E. coli viability was obtained following a 60 min irradiation regimen of the bacteria in the presence of 1 μM synthetic haemozoin and a ~2-log reduction in the presence of 10 μM haemozoin. Minimal (≤15%) cell kill was observed in the presence of 10 μM haemin. Conclusions Laser-induced third-harmonic generation by haemozoin can be used to inactivate Plasmodium. This result may have clinical implications for treating severe malaria symptoms by irradiating the patient’s blood through the skin or through dialysis tubing with a NIR laser. PMID:22873646

  15. Plasmodium vivax Populations Are More Genetically Diverse and Less Structured than Sympatric Plasmodium falciparum Populations

    PubMed Central

    Jennison, Charlie; Arnott, Alicia; Tessier, Natacha; Tavul, Livingstone; Koepfli, Cristian; Felger, Ingrid; Siba, Peter M.; Reeder, John C.; Bahlo, Melanie; Mueller, Ivo; Barry, Alyssa E.

    2015-01-01

    Introduction The human malaria parasite, Plasmodium vivax, is proving more difficult to control and eliminate than Plasmodium falciparum in areas of co-transmission. Comparisons of the genetic structure of sympatric parasite populations may provide insight into the mechanisms underlying the resilience of P. vivax and can help guide malaria control programs. Methodology/Principle findings P. vivax isolates representing the parasite populations of four areas on the north coast of Papua New Guinea (PNG) were genotyped using microsatellite markers and compared with previously published microsatellite data from sympatric P. falciparum isolates. The genetic diversity of P. vivax (He = 0.83–0.85) was higher than that of P. falciparum (He = 0.64–0.77) in all four populations. Moderate levels of genetic differentiation were found between P. falciparum populations, even over relatively short distances (less than 50 km), with 21–28% private alleles and clear geospatial genetic clustering. Conversely, very low population differentiation was found between P. vivax catchments, with less than 5% private alleles and no genetic clustering observed. In addition, the effective population size of P. vivax (30353; 13043–69142) was larger than that of P. falciparum (18871; 8109–42986). Conclusions/Significance Despite comparably high prevalence, P. vivax had higher diversity and a panmictic population structure compared to sympatric P. falciparum populations, which were fragmented into subpopulations. The results suggest that in comparison to P. falciparum, P. vivax has had a long-term large effective population size, consistent with more intense and stable transmission, and limited impact of past control and elimination efforts. This underlines suggestions that more intensive and sustained interventions will be needed to control and eventually eliminate P. vivax. This research clearly demonstrates how population genetic analyses can reveal deeper insight into transmission

  16. Plasmodium falciparum Malaria Endemicity in Indonesia in 2010

    PubMed Central

    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

  17. Plasmodium falciparum malaria endemicity in Indonesia in 2010.

    PubMed

    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

    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. 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 (PfPR(2-10)) for endemicity mapping. A Bayesian MBG procedure was used to create a predicted surface of PfPR(2-10) endemicity with uncertainty estimates. Population at risk estimates were derived with reference to a 2010 human population count surface. 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. 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 future strategies against this 2010 baseline

  18. Dissecting the role of glutathione biosynthesis in Plasmodium falciparum

    PubMed Central

    Patzewitz, Eva-Maria; Wong, Eleanor H; Müller, Sylke

    2012-01-01

    Glutathione (γ-glutamylcysteinyl-glycine, GSH) has vital functions as thiol redox buffer and cofactor of antioxidant and detoxification enzymes. Plasmodium falciparum possesses a functional GSH biosynthesis pathway and contains mM concentrations of the tripeptide. It was impossible to delete in P. falciparum the genes encoding γ-glutamylcysteine synthetase (γGCS) or glutathione synthetase (GS), the two enzymes synthesizing GSH, although both gene loci were not refractory to recombination. Our data show that the parasites cannot compensate for the loss of GSH biosynthesis via GSH uptake. This suggests an important if not essential function of GSH biosynthesis pathway for the parasites. Treatment with the irreversible inhibitor of γGCS L-buthionine sulfoximine (BSO) reduced intracellular GSH levels in P. falciparum and was lethal for their intra-erythrocytic development, corroborating the suggestion that GSH biosynthesis is important for parasite survival. Episomal expression of γgcs in P. falciparum increased tolerance to BSO attributable to increased levels of γGCS. Concomitantly expression of glutathione reductase was reduced leading to an increased GSH efflux. Together these data indicate that GSH levels are tightly regulated by a functional GSH biosynthesis and the reduction of GSSG. PMID:22151036

  19. Expression and characterization of the Plasmodium falciparum haemoglobinase falcipain-3.

    PubMed Central

    Sijwali, P S; Shenai, B R; Gut, J; Singh, A; Rosenthal, P J

    2001-01-01

    In the malaria parasite Plasmodium falciparum, erythrocytic trophozoites hydrolyse haemoglobin to provide amino acids for parasite protein synthesis. Cysteine protease inhibitors block parasite haemoglobin hydrolysis and development, indicating that cysteine proteases are required for these processes. Three papain-family cysteine protease sequences have been identified in the P. falciparum genome, but the specific roles of their gene products and other plasmodial proteases in haemoglobin hydrolysis are uncertain. Falcipain-2 was recently identified as a principal trophozoite cysteine protease and potential drug target. The present study characterizes the related P. falciparum cysteine protease falcipain-3. As is the case with falcipain-2, falcipain-3 is expressed by trophozoites and appears to be located within the food vacuole, the site of haemoglobin hydrolysis. Both proteases require a reducing environment and acidic pH for optimal activity, and both prefer peptide substrates with leucine at the P(2) position. The proteases differ, however, in that falcipain-3 undergoes efficient processing to an active form only at acidic pH, is more active and stable at acidic pH, and has much lower specific activity against typical papain-family peptide substrates, but has greater activity against native haemoglobin. Thus falcipain-3 is a second P. falciparum haemoglobinase that is particularly suited for the hydrolysis of native haemoglobin in the acidic food vacuole. The redundancy of cysteine proteases may offer optimized hydrolysis of both native haemoglobin and globin peptides. Consideration of both proteases will be necessary to evaluate cysteine protease inhibitors as antimalarial drugs. PMID:11716777

  20. A genome-wide map of diversity in Plasmodium falciparum.

    PubMed

    Volkman, Sarah K; Sabeti, Pardis C; DeCaprio, David; Neafsey, Daniel E; Schaffner, Stephen F; Milner, Danny A; Daily, Johanna P; Sarr, Ousmane; Ndiaye, Daouda; Ndir, Omar; Mboup, Soulyemane; Duraisingh, Manoj T; Lukens, Amanda; Derr, Alan; Stange-Thomann, Nicole; Waggoner, Skye; Onofrio, Robert; Ziaugra, Liuda; Mauceli, Evan; Gnerre, Sante; Jaffe, David B; Zainoun, Joanne; Wiegand, Roger C; Birren, Bruce W; Hartl, Daniel L; Galagan, James E; Lander, Eric S; Wirth, Dyann F

    2007-01-01

    Genetic variation allows the malaria parasite Plasmodium falciparum to overcome chemotherapeutic agents, vaccines and vector control strategies and remain a leading cause of global morbidity and mortality. Here we describe an initial survey of genetic variation across the P. falciparum genome. We performed extensive sequencing of 16 geographically diverse parasites and identified 46,937 SNPs, demonstrating rich diversity among P. falciparum parasites (pi = 1.16 x 10(-3)) and strong correlation with gene function. We identified multiple regions with signatures of selective sweeps in drug-resistant parasites, including a previously unidentified 160-kb region with extremely low polymorphism in pyrimethamine-resistant parasites. We further characterized 54 worldwide isolates by genotyping SNPs across 20 genomic regions. These data begin to define population structure among African, Asian and American groups and illustrate the degree of linkage disequilibrium, which extends over relatively short distances in African parasites but over longer distances in Asian parasites. We provide an initial map of genetic diversity in P. falciparum and demonstrate its potential utility in identifying genes subject to recent natural selection and in understanding the population genetics of this parasite.

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

    PubMed

    Qidwai, Tabish; Jamal, Farrukh; Khan, Mohd Y; Sharma, Bechan

    2014-01-01

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

  2. Symmetrical peripheral gangrene due to Plasmodium falciparum malaria

    PubMed Central

    Abdali, Nasar; Malik, Azharuddin Mohammed; Kamal, Athar; Ahmad, Mehtab

    2014-01-01

    A 45-year-old man presented with a 4-day history of high-grade fever with rigours and a 2-day history of painful bluish black discolouration of extremities (acrocyanosis). He was haemodynamically stable and all peripheral pulses palpable, but the extremities were cold with gangrene involving bilateral fingers and toes. Mild splenomegaly was present on abdominal examination but rest of the physical examinations were normal. On investigating he was found to have anaemia, thrombocytopaenia with gametocytes of Plasmodium falciparum on peripheral blood smear. His blood was uncoagulable during performance of prothrombin time with a raised D-dimer. Oxygen saturation was normal and the arterial Doppler test showed reduced blood flow to the extremities. A diagnosis of complicated P. falciparum malaria with disseminated intravascular coagulation (DIC) leading to symmetrical peripheral gangrene was performed. Artemisinin combination therapy was started and heparin was given for DIC. A final line of demarcation of gangrene started forming by 12th day. PMID:24862424

  3. The mechanism of resistance to sulfa drugs in Plasmodium falciparum.

    PubMed

    Triglia, Tony; Cowman, Alan F.

    1999-02-01

    The sulfonamide and sulfone (sulfa) group of antimalarials has been used extensively throughout malaria endemic regions of the world to control this important infectious disease of humans. Sulfadoxine is the most extensively used drug of this group of drugs and is usually combined with pyrimethamine (Fansidar), particularly for the control of Plasmodium falciparum, the causative agent of the most lethal form of malaria. Resistance to the sulfadoxine/pyrimethamine combination is widespread. Analysis using molecular, genetic and biochemical approaches has shown that the mechanism of resistance to sulfadoxine involves mutation of dihydropteroate synthase, the enzyme target of this group of drugs. Understanding the mechanism of resistance of P. falciparum to sulfa drugs has allowed detailed analysis of the epidemiology of the spread of drug resistance alleles in the field(1)and, in the future, opens the way to the development of novel antimalarials to this target enzyme. Copyright 1999 Harcourt Publishers Ltd.

  4. A genetic system to study Plasmodium falciparum protein function.

    PubMed

    Birnbaum, Jakob; Flemming, Sven; Reichard, Nick; Soares, Alexandra Blancke; Mesén-Ramírez, Paolo; Jonscher, Ernst; Bergmann, Bärbel; Spielmann, Tobias

    2017-03-13

    Current systems to study essential genes in the human malaria parasite Plasmodium falciparum are often inefficient and time intensive, and they depend on the genetic modification of the target locus, a process hindered by the low frequency of integration of episomal DNA into the genome. Here, we introduce a method, termed selection-linked integration (SLI), to rapidly select for genomic integration. SLI allowed us to functionally analyze targets at the gene and protein levels, thus permitting mislocalization of native proteins, a strategy known as knock sideways, floxing to induce diCre-based excision of genes and knocking in altered gene copies. We demonstrated the power and robustness of this approach by validating it for more than 12 targets, including eight essential ones. We also localized and inducibly inactivated Kelch13, the protein associated with artemisinin resistance. We expect this system to be widely applicable for P. falciparum and other organisms with limited genetic tractability.

  5. Characterization of the 26S proteasome network in Plasmodium falciparum.

    PubMed

    Wang, Lihui; Delahunty, Claire; Fritz-Wolf, Karin; Rahlfs, Stefan; Helena Prieto, Judith; Yates, John R; Becker, Katja

    2015-12-07

    In eukaryotic cells, the ubiquitin-proteasome system as a key regulator of protein quality control is an excellent drug target. We therefore aimed to analyze the 26S proteasome complex in the malaria parasite Plasmodium falciparum, which still threatens almost half of the world's population. First, we established an affinity purification protocol allowing for the isolation of functional 26S proteasome complexes from the parasite. Subunit composition of the proteasome and component stoichiometry were studied and physiologic interacting partners were identified via in situ protein crosslinking. Furthermore, intrinsic ubiquitin receptors of the plasmodial proteasome were determined and their roles in proteasomal substrate recognition were analyzed. Notably, PfUSP14 was characterized as a proteasome-associated deubiquitinase resulting in the concept that targeting proteasomal deubiquitinating activity in P. falciparum may represent a promising antimalarial strategy. The data provide insights into a profound network orchestrated by the plasmodial proteasome and identified novel drug target candidates in the ubiquitin-proteasome system.

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

    PubMed Central

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

    2016-01-01

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

  7. Plasmodium falciparum MLH is schizont stage specific endonuclease.

    PubMed

    Tarique, Mohammed; Satsangi, Akash Tripathi; Ahmad, Moaz; Singh, Shailja; Tuteja, Renu

    2012-02-01

    Malaria is one of the most important infectious diseases in many regions around the world including India. Plasmodium falciparum is the cause of most lethal form of malaria while Plasmodium vivax is the major cause outside Africa. Regardless of considerable efforts over the last many years there is still no commercial vaccine against malaria and the disease is mainly treated using a range of established drugs. With time, the malaria parasite is developing drug resistance to most of the commonly used drugs. This drug resistance might be due to defective mismatch repair in the parasite. Previously we have reported that the P. falciparum genome contains homologues to most of the components of mismatch repair (MMR) complex. In the present study we report the detailed biochemical characterization of one of the main component of MMR complex, MLH, from P. falciparum. Our results show that MLH is an ATPase and it can incise covalently closed circular DNA in the presence of Mn(2+) or Mg(2+) ions. Using the truncated derivatives we show that full length protein MLH is required for all the enzymatic activities. Using immunodepletion assays we further show that the ATPase and endomuclease activities are attributable to PfMLH protein. Using immunofluorescence assay we report that the peak expression of MLH in both 3D7 and Dd2 strains of P. falciparum is mainly in the schizont stages of the intraerythrocytic development, where DNA replication is active. MMR also contributes to the overall fidelity of DNA replication and the peak expression of MLH in the schizont stages suggests that MLH is most likely involved in correcting the mismatches occurring during replication. This study should make a significant contribution in our better understanding of DNA metabolic processes in the parasite.

  8. Chloroquine accumulation by purified plasma membranes from Plasmodium falciparum.

    PubMed

    Elandaloussi, Laurence M; Smith, Peter J

    2006-01-01

    Resistance of Plasmodium falciparum to chloroquine (CQ) has been associated with a decrease in CQ accumulation by parasitized erythrocytes. This study aimed at investigating the role of parasite plasma membranes (PPM) in the mechanism of CQ accumulation. CQ accumulation capabilities of membranes were determined using tritiated CQ. PPM isolated from chloroquine-sensitive parasites were found to accumulate less CQ than those isolated from chloroquine-resistant parasites. However, CQ accumulation was found to be ATP-independent suggesting that this accumulation results from binding rather than transport.

  9. Proteomics of the human malaria parasite Plasmodium falciparum.

    PubMed

    Sims, Paul F G; Hyde, John E

    2006-02-01

    The lethal species of malaria parasite, Plasmodium falciparum, continues to exact a huge toll of mortality and morbidity, particularly in sub-Saharan Africa. Completion of the genome sequence of this organism and advances in proteomics and mass spectrometry have opened up unprecedented opportunities for understanding the complex biology of this parasite and how it responds to drug challenge and other interventions. This review describes recent progress that has been made in applying proteomics technology to this important pathogen and provides a look forward to likely future developments.

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

    PubMed

    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.

  11. Plasmodium falciparum drug resistance in Angola.

    PubMed

    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.

  12. Wanted Plasmodium falciparum, dead or alive

    PubMed Central

    Sow, Fatimata; Nyonda, Mary; Bienvenu, Anne-Lise; Picot, Stephane

    2015-01-01

    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. PMID:28357297

  13. Interaction of an atypical Plasmodium falciparum ETRAMP with human apolipoproteins

    PubMed Central

    Vignali, Marissa; McKinlay, Anastasia; LaCount, Douglas J; Chettier, Rakesh; Bell, Russell; Sahasrabudhe, Sudhir; Hughes, Robert E; Fields, Stanley

    2008-01-01

    Background In order to establish a successful infection in the human host, the malaria parasite Plasmodium falciparum must establish interactions with a variety of human proteins on the surface of different cell types, as well as with proteins inside the host cells. To better understand this aspect of malaria pathogenesis, a study was conducted with the goal of identifying interactions between proteins of the parasite and those of its human host. Methods A modified yeast two-hybrid methodology that preferentially selects protein fragments that can be expressed in yeast was used to conduct high-throughput screens with P. falciparum protein fragments against human liver and cerebellum libraries. The resulting dataset was analyzed to exclude interactions that are not likely to occur in the human host during infection. Results An initial set of 2,200 interactions was curated to remove proteins that are unlikely to play a role in pathogenesis based on their annotation or localization, and proteins that behave promiscuously in the two-hybrid assay, resulting in a final dataset of 456 interactions. A cluster that implicates binding between P. falciparum PFE1590w/ETRAMP5, a putative parasitophorous vacuole membrane protein, and human apolipoproteins ApoA, ApoB and ApoE was selected for further analysis. Different isoforms of ApoE, which are associated with different outcomes of malaria infection, were shown to display differential interactions with PFE1590w. Conclusion A dataset of interactions between proteins of P. falciparum and those of its human host was generated. The preferential interaction of the P. falciparum PFE1590w protein with the human ApoE ε3 and ApoE ε4 isoforms, but not the ApoE ε2 isoform, supports the hypothesis that ApoE genotype affects risk of malaria infection. The dataset contains other interactions of potential relevance to disease that may identify possible vaccine candidates and drug targets. PMID:18937849

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

    PubMed

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

    2015-07-16

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

  15. Production of recombinant proteins from Plasmodium falciparum in Escherichia coli.

    PubMed

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

    2016-02-23

    The production of recombinant proteins is essential for the characterization and functional study of proteins from Plasmodium falciparum. However, the proteins of P. falciparum are among the most challenging to express, and when expression is achieved, the recombinant proteins usually fold incorrectly and lead to the formation of inclusion bodies.  To obtain and purify four recombinant proteins and to use them as antigens to produce polyclonal antibodies. The production efficiency and solubility were evaluated as the proteins were expressed in two genetically modified strains of Escherichia coli to favor the production of heterologous proteins (BL21-CodonPlus (DE3)-RIL and BL21-pG-KJE8).  The four recombinant P. falciparum proteins corresponding to partial sequences of PfMyoA (Myosin A) and PfGAP50 (gliding associated protein 50), and the complete sequences of PfMTIP (myosin tail interacting protein) and PfGAP45 (gliding associated protein 45), were produced as glutathione S-transferase-fusion proteins, purified and used for immunizing mice.  The protein expression was much more efficient in BL21-CodonPlus, the strain that contains tRNAs that are rare in wild-type E. coli, compared to the expression in BL21-pG-KJE8. In spite of the fact that BL21-pG-KJE8 overexpresses chaperones, this strain did not minimize the formation of inclusion bodies.  The use of genetically modified strains of E. coli was essential to achieve high expression levels of the four evaluated P. falciparum proteins and lead to improved solubility of two of them. The approach used here allowed us to obtain and purify four P. falciparum proteins in enough quantity to produce polyclonal antibodies in mice, and a fair amount of two pure and soluble recombinant proteins for future assays.

  16. DNA Cloning of Plasmodium falciparum Circumsporozoite Gene: Amino Acid Sequence of Repetitive Epitope

    NASA Astrophysics Data System (ADS)

    Enea, Vincenzo; Ellis, Joan; Zavala, Fidel; Arnot, David E.; Asavanich, Achara; Masuda, Aoi; Quakyi, Isabella; Nussenzweig, Ruth S.

    1984-08-01

    A clone of complementary DNA encoding the circumsporozoite (CS) protein of the human malaria parasite Plasmodium falciparum has been isolated by screening an Escherichia coli complementary DNA library with a monoclonal antibody to the CS protein. The DNA sequence of the complementary DNA insert encodes a four-amino acid sequence: proline-asparagine-alanine-asparagine, tandemly repeated 23 times. The CS β -lactamase fusion protein specifically binds monoclonal antibodies to the CS protein and inhibits the binding of these antibodies to native Plasmodium falciparum CS protein. These findings provide a basis for the development of a vaccine against Plasmodium falciparum malaria.

  17. Alternative Protein Secretion in the Malaria Parasite Plasmodium falciparum

    PubMed Central

    Thavayogarajah, Thuvaraka; Gangopadhyay, Preetish; Rahlfs, Stefan; Becker, Katja; Lingelbach, Klaus; Przyborski, Jude M.; Holder, Anthony A.

    2015-01-01

    Plasmodium falciparum invades human red blood cells, residing in a parasitophorous vacuole (PV), with a parasitophorous vacuole membrane (PVM) separating the PV from the host cell cytoplasm. Here we have investigated the role of N-myristoylation and two other N-terminal motifs, a cysteine potential S-palmitoylation site and a stretch of basic residues, as the driving force for protein targeting to the parasite plasma membrane (PPM) and subsequent translocation across this membrane. Plasmodium falciparum adenylate kinase 2 (Pf AK2) contains these three motifs, and was previously proposed to be targeted beyond the parasite to the PVM, despite the absence of a signal peptide for entry into the classical secretory pathway. Biochemical and microscopy analyses of PfAK2 variants tagged with green fluorescent protein (GFP) showed that these three motifs are involved in targeting the protein to the PPM and translocation across the PPM to the PV. It was shown that the N-terminal 37 amino acids of PfAK2 alone are sufficient to target and translocate GFP across the PPM. As a control we examined the N-myristoylated P. falciparum ADP-ribosylation factor 1 (PfARF1). PfARF1 was found to co-localise with a Golgi marker. To determine whether or not the putative palmitoylation and the cluster of lysine residues from the N-terminus of PfAK2 would modulate the subcellular localization of PfARF1, a chimeric fusion protein containing the N-terminus of PfARF1 and the two additional PfAK2 motifs was analysed. This chimeric protein was targeted to the PPM, but not translocated across the membrane into the PV, indicating that other features of the N-terminus of PfAK2 also play a role in the secretion process. PMID:25909331

  18. The crystal structure of superoxide dismutase from Plasmodium falciparum

    PubMed Central

    Boucher, Ian W; Brzozowski, Andrzej M; Brannigan, James A; Schnick, Claudia; Smith, Derek J; Kyes, Sue A; Wilkinson, Anthony J

    2006-01-01

    Background Superoxide dismutases (SODs) are important enzymes in defence against oxidative stress. In Plasmodium falciparum, they may be expected to have special significance since part of the parasite life cycle is spent in red blood cells where the formation of reactive oxygen species is likely to be promoted by the products of haemoglobin breakdown. Thus, inhibitors of P. falciparum SODs have potential as anti-malarial compounds. As a step towards their development we have determined the crystal structure of the parasite's cytosolic iron superoxide dismutase. Results The cytosolic iron superoxide dismutase from P. falciparum (PfFeSOD) has been overexpressed in E. coli in a catalytically active form. Its crystal structure has been solved by molecular replacement and refined against data extending to 2.5 Å resolution. The structure reveals a two-domain organisation and an iron centre in which the metal is coordinated by three histidines, an aspartate and a solvent molecule. Consistent with ultracentrifugation analysis the enzyme is a dimer in which a hydrogen bonding lattice links the two active centres. Conclusion The tertiary structure of PfFeSOD is very similar to those of a number of other iron-and manganese-dependent superoxide dismutases, moreover the active site residues are conserved suggesting a common mechanism of action. Comparison of the dimer interfaces of PfFeSOD with the human manganese-dependent superoxide dismutase reveals a number of differences, which may underpin the design of parasite-selective superoxide dismutase inhibitors. PMID:17020617

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

    PubMed

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

    PubMed Central

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

    2014-01-01

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

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

    PubMed Central

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

    2008-01-01

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

  2. Plasmodium falciparum phosphoethanolamine methyltransferase is essential for malaria transmission

    PubMed Central

    Bobenchik, April M.; Witola, William H.; Augagneur, Yoann; Nic Lochlainn, Laura; Garg, Aprajita; Pachikara, Niseema; Choi, Jae-Yeon; Zhao, Yang O.; Usmani-Brown, Sahar; Lee, Albert; Adjalley, Sophie H.; Samanta, Swapna; Fidock, David A.; Voelker, Dennis R.; Fikrig, Erol; Ben Mamoun, Choukri

    2013-01-01

    Efficient transmission of Plasmodium species between humans and Anopheles mosquitoes is a major contributor to the global burden of malaria. Gametocytogenesis, the process by which parasites switch from asexual replication within human erythrocytes to produce male and female gametocytes, is a critical step in malaria transmission and Plasmodium genetic diversity. Nothing is known about the pathways that regulate gametocytogenesis and only few of the current drugs that inhibit asexual replication are also capable of inhibiting gametocyte development and blocking malaria transmission. Here we provide genetic and pharmacological evidence indicating that the pathway for synthesis of phosphatidylcholine in Plasmodium falciparum membranes from host serine is essential for parasite gametocytogenesis and malaria transmission. Parasites lacking the phosphoethanolamine N-methyltransferase enzyme, which catalyzes the limiting step in this pathway, are severely altered in gametocyte development, are incapable of producing mature-stage gametocytes, and are not transmitted to mosquitoes. Chemical screening identified 11 inhibitors of phosphoethanolamine N-methyltransferase that block parasite intraerythrocytic asexual replication and gametocyte differentiation in the low micromolar range. Kinetic studies in vitro as well as functional complementation assays and lipid metabolic analyses in vivo on the most promising inhibitor NSC-158011 further demonstrated the specificity of inhibition. These studies set the stage for further optimization of NSC-158011 for development of a class of dual activity antimalarials to block both intraerythrocytic asexual replication and gametocytogenesis. PMID:24145416

  3. The Fragmented Mitochondrial Ribosomal RNAs of Plasmodium falciparum

    PubMed Central

    Feagin, Jean E.; Harrell, Maria Isabel; Lee, Jung C.; Coe, Kevin J.; Sands, Bryan H.; Cannone, Jamie J.; Tami, Germaine; Schnare, Murray N.; Gutell, Robin R.

    2012-01-01

    Background The mitochondrial genome in the human malaria parasite Plasmodium falciparum is most unusual. Over half the genome is composed of the genes for three classic mitochondrial proteins: cytochrome oxidase subunits I and III and apocytochrome b. The remainder encodes numerous small RNAs, ranging in size from 23 to 190 nt. Previous analysis revealed that some of these transcripts have significant sequence identity with highly conserved regions of large and small subunit rRNAs, and can form the expected secondary structures. However, these rRNA fragments are not encoded in linear order; instead, they are intermixed with one another and the protein coding genes, and are coded on both strands of the genome. This unorthodox arrangement hindered the identification of transcripts corresponding to other regions of rRNA that are highly conserved and/or are known to participate directly in protein synthesis. Principal Findings The identification of 14 additional small mitochondrial transcripts from P. falcipaurm and the assignment of 27 small RNAs (12 SSU RNAs totaling 804 nt, 15 LSU RNAs totaling 1233 nt) to specific regions of rRNA are supported by multiple lines of evidence. The regions now represented are highly similar to those of the small but contiguous mitochondrial rRNAs of Caenorhabditis elegans. The P. falciparum rRNA fragments cluster on the interfaces of the two ribosomal subunits in the three-dimensional structure of the ribosome. Significance All of the rRNA fragments are now presumed to have been identified with experimental methods, and nearly all of these have been mapped onto the SSU and LSU rRNAs. Conversely, all regions of the rRNAs that are known to be directly associated with protein synthesis have been identified in the P. falciparum mitochondrial genome and RNA transcripts. The fragmentation of the rRNA in the P. falciparum mitochondrion is the most extreme example of any rRNA fragmentation discovered. PMID:22761677

  4. PLASMODIUM FALCIPARUM Na+/H+ EXCHANGER ACTIVITY AND QUININE RESISTANCE +

    PubMed Central

    Bennett, Tyler N.; Patel, Jigar; Ferdig, Michael T.; Roepe, Paul D.

    2009-01-01

    Mutations in the Plasmodium falciparum pfcrt gene cause resistance to the 4 – amino quinoline chloroquine (CQ) and other antimalarial drugs. Mutations and/or overexpression of a P. falciparum multidrug resistance gene homologue (pfmdr1) may further modify or tailor the degree of quinoline drug resistance. Recently (M.T. Ferdig et al., Molecular Microbiology 52: 985–997 [2004]) QTL analysis further implicated a region of P. falciparum chromosome 13 as a partner (with pfcrt) in conferring resistance to the first quinoline – based antimalarial drug, quinine (QN). Since QN resistance (QNR) and CQR are often (but not always) observed together in parasite strains, since elevated cytosolic pH is frequently (but not always) found in CQR parasites, and since the chr 13 segment linked to QNR prominently harbors a gene encoding what appears to be a P. falciparum Na+/H+ exchanger (PfNHE), we have systematically measured cytosolic pH and PfNHE activity for an extended series of parasite strains used in the QTL analysis. Altered PfNHE activity does not correlate with CQR as previously proposed, but significantly elevated PfNHE activity is found for strains with high levels of QNR, regardless their CQR status. We propose that either an elevated pHcyt or a higher vacuolar pH – to – cytosolic pH gradient contributes to one common route to malarial QNR that is also characterized by recently defined chr 13 – chr 9 pairwise interactions. Based on sequence analysis we propose a model whereby observed polymorphisms in PfNHE may lead to altered Na+/H+ set point regulation in QNR parasites. PMID:17353059

  5. Re-evaluation of microscopy confirmed Plasmodium falciparum and Plasmodium vivax malaria by nested PCR detection in southern Ethiopia.

    PubMed

    Mekonnen, Seleshi Kebede; Aseffa, Abraham; Medhin, Girmay; Berhe, Nega; Velavan, Thirumalaisamy P

    2014-02-06

    With 75% of the Ethiopian population at risk of malaria, accurate diagnosis is crucial for malaria treatment in endemic areas where Plasmodium falciparum and Plasmodium vivax co-exist. The present study evaluated the performance of regular microscopy in accurate identification of Plasmodium spp. in febrile patients visiting health facilities in southern Ethiopia. A cross-sectional study design was employed to recruit study subjects who were microscopically positive for malaria parasites and attending health facilities in southern Ethiopia between August and December 2011. Of the 1,416 febrile patients attending primary health facilities, 314 febrile patients, whose slides were positive for P. falciparum, P. vivax or mixed infections using microscopy, were re-evaluated for their infection status by PCR. Finger-prick blood samples were used for parasite genomic DNA extraction. Phylogenetic analyses were performed to reconstruct the distribution of different Plasmodium spp. across the three geographical areas. Of the 314 patients with a positive thick blood smear, seven patients (2%) were negative for any of the Plasmodium spp. by nested PCR. Among 180 microscopically diagnosed P. falciparum cases, 111 (61.7%) were confirmed by PCR, 44 (24.4%) were confirmed as P. vivax, 18 (10%) had mixed infections with P. falciparum and P. vivax and two (1.1%) were mixed infections with P. falciparum and P. malariae and five (2.8%) were negative for any of the Plasmodium spp. Of 131 microscopically diagnosed P. vivax cases, 110 (84%) were confirmed as P. vivax, 14 (10.7%) were confirmed as P. falciparum, two (1.5%) were P. malariae, three (2.3%) with mixed infections with P. falciparum and P. vivax and two (1.5%) were negative for any of the Plasmodium spp. Plasmodium falciparum and P. vivax mixed infections were observed. Plasmodium malariae was detected as mono and mixed infections in four individuals. False positivity, under-reporting of mixed infections and a significant number

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

    PubMed

    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.

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

    PubMed Central

    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. PMID:27007559

  8. Symmetrical peripheral gangrene: A rare complication of plasmodium falciparum malaria

    PubMed Central

    Rana, Atul; Singh, DP; Kaur, Gurdeep; Verma, SK; Mahur, Hemant

    2015-01-01

    Malaria, the most important of the parasitic diseases of humans, is transmitted in 108 countries containing 3 billion people and causes nearly 1 million deaths each year. With the re-emergence of malaria various life-threatening complications of malaria have been observed. Unarousable coma/cerebral malaria, severe normochromic, normocytic anemia, renal failure, pulmonary edema/adult respiratory distress syndrome, hypoglycemia, hypotension/shock, bleeding/disseminated intravascular coagulation (DIC), hemoglobinuria and jaundice are few of the common complications of severe malaria. Symmetrical peripheral gangrene (SPG) has been reported as a rare complication of malaria. We report a rare and unique case of Plasmodium falciparum malaria complicated by DIC, severe normocytic normochromic anemia, and SPG. PMID:26629458

  9. Haem-activated promiscuous targeting of artemisinin in Plasmodium falciparum

    PubMed Central

    Wang, Jigang; Zhang, Chong-Jing; Chia, Wan Ni; Loh, Cheryl C. Y.; Li, Zhengjun; Lee, Yew Mun; He, Yingke; Yuan, Li-Xia; Lim, Teck Kwang; Liu, Min; Liew, Chin Xia; Lee, Yan Quan; Zhang, Jianbin; Lu, Nianci; Lim, Chwee Teck; Hua, Zi-Chun; Liu, Bin; Shen, Han-Ming; Tan, Kevin S. W.; Lin, Qingsong

    2015-01-01

    The mechanism of action of artemisinin and its derivatives, the most potent of the anti-malarial drugs, is not completely understood. Here we present an unbiased chemical proteomics analysis to directly explore this mechanism in Plasmodium falciparum. We use an alkyne-tagged artemisinin analogue coupled with biotin to identify 124 artemisinin covalent binding protein targets, many of which are involved in the essential biological processes of the parasite. Such a broad targeting spectrum disrupts the biochemical landscape of the parasite and causes its death. Furthermore, using alkyne-tagged artemisinin coupled with a fluorescent dye to monitor protein binding, we show that haem, rather than free ferrous iron, is predominantly responsible for artemisinin activation. The haem derives primarily from the parasite's haem biosynthesis pathway at the early ring stage and from haemoglobin digestion at the latter stages. Our results support a unifying model to explain the action and specificity of artemisinin in parasite killing. PMID:26694030

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

    PubMed Central

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

    2013-01-01

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

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

    PubMed

    Hempel, Casper

    2017-07-01

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

  12. Plasmodium falciparum Rab1A Localizes to Rhoptries in Schizonts

    PubMed Central

    Morse, David; Webster, Wesley; Kalanon, Ming; Langsley, Gordon; McFadden, Geoffrey I.

    2016-01-01

    Over-expression of a GFP-PfRab1A fusion protein in Plasmodium falciparum schizonts produces a punctate pattern of fluorescence typical of rhoptries, secretory organelles involved in host cell invasion. The GFP-positive bodies were purified by a combination of differential and density gradient centrifugation and their protein content determined by MS/MS sequencing. Consistent with the GFP rhoptry-like pattern of transgenic parasites, four of the 19 proteins identified have been previously described to be rhoptry-associated and another four are ER or ER-associated proteins. Confirmation that GFP-PfRab1A decorates rhoptries was obtained by its co-localization with Rap1 and Ron4 in late phase schizonts. We conclude that PfRab1A potentially regulates vesicular traffic from the endoplasmic reticulum to the rhoptries in Apicomplexa parasites. PMID:27348424

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

    PubMed Central

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

    2015-01-01

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

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

    DTIC Science & Technology

    2014-01-01

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

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

    PubMed Central

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

    2007-01-01

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

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

    PubMed

    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.

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

    NASA Astrophysics Data System (ADS)

    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.

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

    PubMed Central

    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

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

    PubMed

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

    2007-10-01

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

  20. Cloning of Plasmodium falciparum by single-cell sorting

    PubMed Central

    Miao, Jun; Li, Xiaolian; Cui, Liwang

    2010-01-01

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

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

    PubMed

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

    2014-01-20

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

  2. Cloning of Plasmodium falciparum by single-cell sorting.

    PubMed

    Miao, Jun; Li, Xiaolian; Cui, Liwang

    2010-10-01

    Malaria parasite cloning is traditionally carried out mainly by using the limiting dilution method, which is laborious, imprecise, and unable to distinguish multiply-infected RBCs. In this study, we used a parasite engineered to express green fluorescent protein (GFP) to evaluate a single-cell sorting method for rapidly cloning Plasmodium falciparum. By dividing a two-dimensional scattergram from a cell sorter into 17 gates, we determined the parameters for isolating singly-infected erythrocytes and sorted them into individual cultures. Pre-gating of the engineered parasites for GFP allowed the isolation of almost 100% GFP-positive clones. Compared with the limiting dilution method, the number of parasite clones obtained by single-cell sorting was much higher. Molecular analyses showed that parasite isolates obtained by single-cell sorting were highly homogenous. This highly efficient single-cell sorting method should prove very useful for cloning both P. falciparum laboratory populations from genetic manipulation experiments and clinical samples. Copyright 2010 Elsevier Inc. All rights reserved.

  3. Current status of the Plasmodium falciparum genome project.

    PubMed

    Dame, J B; Arnot, D E; Bourke, P F; Chakrabarti, D; Christodoulou, Z; Coppel, R L; Cowman, A F; Craig, A G; Fischer, K; Foster, J; Goodman, N; Hinterberg, K; Holder, A A; Holt, D C; Kemp, D J; Lanzer, M; Lim, A; Newbold, C I; Ravetch, J V; Reddy, G R; Rubio, J; Schuster, S M; Su, X Z; Thompson, J K; Werner, E B

    1996-07-01

    The Plasmodium falciparum Genome Project is a collaborative effort by many laboratories that will provide detailed molecular information about the parasite, which may be used for developing practical control measures. Initial goals are to prepare an electronically indexed clone bank containing partially sequenced clones representing up to 80% of the parasite's genes and to prepare an ordered set of overlapping clones spanning each of the parasite's 14 chromosomes. Currently, clones of genomic DNA, prepared as yeast artificial chromosomes, are arranged into contigs covering approximately 70% of the genome of parasite clone 3D7, gene sequence tags are available from more than contigs covering approximately 70% of the genome of parasite clone 3D7, gene sequence tags are available from more than 20% of the parasite's genes, and approximately 5% of the parasite's genes are tentatively identified from similarity searches of entries in the international sequence databases. A total of > 0.5 Mb of P. falciparum sequence tag data is available. The gene sequence tags are presently being used to complete YAC contig assembly and localize the cloned genes to positions on the physical map in preparation for sequencing the genome. Routes of access to project information and services are described.

  4. Sickle Cell Trait Protects Against Plasmodium falciparum Infection

    PubMed Central

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

    2012-01-01

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

  5. Characterisation of exogenous folate transport in Plasmodium falciparum.

    PubMed

    Wang, Ping; Wang, Qi; Sims, Paul F G; Hyde, John E

    2007-07-01

    Folate salvage by Plasmodium falciparum is an important source of key cofactors, but little is known about the underlying mechanism. Using synchronised parasite cultures, we observed that uptake of this dianionic species against the negative-inward electrochemical gradient is highly dependent upon cell-cycle stage, temperature and pH, but not on mono- or divalent metal ions. Energy dependence was tested with different sugars; glucose was necessary for folate import, although fructose was also able to function in this role, unlike sugars that cannot be processed through the glycolytic pathway. Import into both infected erythrocytes and free parasites was strongly inhibited by the anion-channel blockers probenecid and furosemide, which are likely to be acting predominantly on specific folate transporters in both cases. Import was not affected by high concentrations of the antifolate drugs pyrimethamine and sulfadoxine, but was inhibited by the close folate analogue methotrexate. The pH optimum for folate uptake into infected erythrocytes was 6.5-7.0. Dinitrophenol and nigericin, which strongly facilitate the equilibration of H(+) ions across biological membranes and thus abolish or substantially reduce the proton gradient, inhibited folate uptake profoundly. The ATPase inhibitor concanamycin A also greatly reduced folate uptake, further demonstrating a link to ATP-powered proton transport. These data strongly suggest that the principal folate uptake pathway in P. falciparum is specific, highly regulated, dependent upon the proton gradient across the parasite plasma membrane, and is likely to be mediated by one or more proton symporters.

  6. MEIOTIC RECOMBINATION, CROSS-REACTIVITY, AND PERSISTENCE IN PLASMODIUM FALCIPARUM

    PubMed Central

    McKenzie, F. Ellis; Ferreira, Marcelo U.; Baird, J. Kevin; Snounou, Georges; Bossert, William H.

    2008-01-01

    We incorporate a representation of Plasmodium falciparum recombination within a discrete-event model of malaria transmission. We simulate the introduction of a new parasite genotype into a human population in which another genotype has reached equilibrium prevalence and compare the emergence and persistence of the novel recombinant forms under differing cross-reactivity relationships between the genotypes. Cross-reactivity between the parental (initial and introduced) genotypes reduces the frequency of appearance of recombinants within three years of introduction from 100% to 14%, and delays their appearance by more than a year, on average. Cross-reactivity between parental and recombinant genotypes reduces the frequency of appearance to 36% and increases the probability of recombinant extinction following appearance from 0% to 83%. When a recombinant is cross-reactive with its parental types, its probability of extinction is influenced by cross-reactivity between the parental types in the opposite manner; that is, its probability of extinction after appearance decreases. Frequencies of P. falciparum outcrossing are mediated by frequencies of mixed-genotype infections in the host population, which are in turn mediated by the structure of cross-reactivity between parasite genotypes. The three leading hypotheses about how meiosis relates to oocyst production lead to quantitative, but no qualitative, differences in these results. PMID:11525454

  7. Genome sequence of the human malaria parasite Plasmodium falciparum.

    PubMed

    Gardner, Malcolm J; Hall, Neil; Fung, Eula; White, Owen; Berriman, Matthew; Hyman, Richard W; Carlton, Jane M; Pain, Arnab; Nelson, Karen E; Bowman, Sharen; Paulsen, Ian T; James, Keith; Eisen, Jonathan A; Rutherford, Kim; Salzberg, Steven L; Craig, Alister; Kyes, Sue; Chan, Man-Suen; Nene, Vishvanath; Shallom, Shamira J; Suh, Bernard; Peterson, Jeremy; Angiuoli, Sam; Pertea, Mihaela; Allen, Jonathan; Selengut, Jeremy; Haft, Daniel; Mather, Michael W; Vaidya, Akhil B; Martin, David M A; Fairlamb, Alan H; Fraunholz, Martin J; Roos, David S; Ralph, Stuart A; McFadden, Geoffrey I; Cummings, Leda M; Subramanian, G Mani; Mungall, Chris; Venter, J Craig; Carucci, Daniel J; Hoffman, Stephen L; Newbold, Chris; Davis, Ronald W; Fraser, Claire M; Barrell, Bart

    2002-10-03

    The parasite Plasmodium falciparum is responsible for hundreds of millions of cases of malaria, and kills more than one million African children annually. Here we report an analysis of the genome sequence of P. falciparum clone 3D7. The 23-megabase nuclear genome consists of 14 chromosomes, encodes about 5,300 genes, and is the most (A + T)-rich genome sequenced to date. Genes involved in antigenic variation are concentrated in the subtelomeric regions of the chromosomes. Compared to the genomes of free-living eukaryotic microbes, the genome of this intracellular parasite encodes fewer enzymes and transporters, but a large proportion of genes are devoted to immune evasion and host-parasite interactions. Many nuclear-encoded proteins are targeted to the apicoplast, an organelle involved in fatty-acid and isoprenoid metabolism. The genome sequence provides the foundation for future studies of this organism, and is being exploited in the search for new drugs and vaccines to fight malaria.

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

    PubMed Central

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

    2003-01-01

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

  9. In vitro sensitivity of Plasmodium falciparum to artesunate in Thailand.

    PubMed Central

    Wongsrichanalai, C.; Wimonwattrawatee, T.; Sookto, P.; Laoboonchai, A.; Heppner, D. G.; Kyle, D. E.; Wernsdorfer, W. H.

    1999-01-01

    Reported are the in vitro susceptibilities of Plasmodium falciparum to artesunate, mefloquine, quinine and chloroquine of 86 isolates and to dihydroartemisinin of 45 isolates collected from areas of high resistance to mefloquine within Thailand near the borders with Myanmar and Cambodia, and from southern Thailand where P. falciparum is generally still sensitive to mefloquine. All the isolates were highly sensitive to artesunate, but the geometric mean IC50S were higher in isolates from the Thai-Myanmar and Thai-Cambodian borders than in those from southern Thailand. The IC50S for mefloquine and artesunate were strongly correlated (Pearson r = 0.605; n = 86; P < 0.00001). As expected, the in vitro sensitivities to dihydroartemisinin and artesunate were similar and strongly correlated (at IC50, Pearson r = 0.695; n = 45; P < 0.00002). The correlation between the activity of mefloquine and artesunate requires further investigation in order to determine the potential for development of cross-resistance in nature. Our results suggest that combination with mefloquine is not the ideal way of protecting the usefulness of artemisinin and its derivatives. A search for more suitable partner drugs to these compounds and careful regulation of their use are necessary in the interest of ensuring their long therapeutic life span. PMID:10361756

  10. Seasonality of Plasmodium falciparum transmission: a systematic review.

    PubMed

    Reiner, Robert C; Geary, Matthew; Atkinson, Peter M; Smith, David L; Gething, Peter W

    2015-09-15

    Although Plasmodium falciparum transmission frequently exhibits seasonal patterns, the drivers of malaria seasonality are often unclear. Given the massive variation in the landscape upon which transmission acts, intra-annual fluctuations are likely influenced by different factors in different settings. Further, the presence of potentially substantial inter-annual variation can mask seasonal patterns; it may be that a location has "strongly seasonal" transmission and yet no single season ever matches the mean, or synoptic, curve. Accurate accounting of seasonality can inform efficient malaria control and treatment strategies. In spite of the demonstrable importance of accurately capturing the seasonality of malaria, data required to describe these patterns is not universally accessible and as such localized and regional efforts at quantifying malaria seasonality are disjointed and not easily generalized. The purpose of this review was to audit the literature on seasonality of P. falciparum and quantitatively summarize the collective findings. Six search terms were selected to systematically compile a list of papers relevant to the seasonality of P. falciparum transmission, and a questionnaire was developed to catalogue the manuscripts. 152 manuscripts were identified as relating to the seasonality of malaria transmission, deaths due to malaria or the population dynamics of mosquito vectors of malaria. Among these, there were 126 statistical analyses and 31 mechanistic analyses (some manuscripts did both). Identified relationships between temporal patterns in malaria and climatological drivers of malaria varied greatly across the globe, with different drivers appearing important in different locations. Although commonly studied drivers of malaria such as temperature and rainfall were often found to significantly influence transmission, the lags between a weather event and a resulting change in malaria transmission also varied greatly by location. The contradicting

  11. Identification of Novel Plasmodium falciparum Hexokinase Inhibitors with Antiparasitic Activity

    PubMed Central

    Davis, Mindy I.; Patrick, Stephen L.; Blanding, Walker M.; Dwivedi, Varun; Suryadi, Jimmy; Coussens, Nathan P.; Lee, Olivia W.; Shen, Min; Boxer, Matthew B.; Hall, Matthew D.; Sharlow, Elizabeth R.; Drew, Mark E.

    2016-01-01

    Plasmodium falciparum, the deadliest species of malaria parasites, is dependent on glycolysis for the generation of ATP during the pathogenic red blood cell stage. Hexokinase (HK) catalyzes the first step in glycolysis, transferring the γ-phosphoryl group of ATP to glucose to yield glucose-6-phosphate. Here, we describe the validation of a high-throughput assay for screening small-molecule collections to identify inhibitors of the P. falciparum HK (PfHK). The assay, which employed an ADP-Glo reporter system in a 1,536-well-plate format, was robust with a signal-to-background ratio of 3.4 ± 1.2, a coefficient of variation of 6.8% ± 2.9%, and a Z′-factor of 0.75 ± 0.08. Using this assay, we screened 57,654 molecules from multiple small-molecule collections. Confirmed hits were resolved into four clusters on the basis of structural relatedness. Multiple singleton hits were also identified. The most potent inhibitors had 50% inhibitory concentrations as low as ∼1 μM, and several were found to have low-micromolar 50% effective concentrations against asexual intraerythrocytic-stage P. falciparum parasites. These molecules additionally demonstrated limited toxicity against a panel of mammalian cells. The identification of PfHK inhibitors with antiparasitic activity using this validated screening assay is encouraging, as it justifies additional HTS campaigns with more structurally amenable libraries for the identification of potential leads for future therapeutic development. PMID:27458230

  12. Plasmodium falciparum Maf1 Confers Survival upon Amino Acid Starvation

    PubMed Central

    McLean, Kyle Jarrod

    2017-01-01

    ABSTRACT The target of rapamycin complex 1 (TORC1) pathway is a highly conserved signaling pathway across eukaryotes that integrates nutrient and stress signals to regulate the cellular growth rate and the transition into and maintenance of dormancy. The majority of the pathway’s components, including the central TOR kinase, have been lost in the apicomplexan lineage, and it is unknown how these organisms detect and respond to nutrient starvation in its absence. Plasmodium falciparum encodes a putative ortholog of the RNA polymerase (Pol) III repressor Maf1, which has been demonstrated to modulate Pol III transcription in a TOR-dependent manner in a number of organisms. Here, we investigate the role of P. falciparum Maf1 (PfMaf1) in regulating RNA Pol III expression under conditions of nutrient starvation and other stresses. Using a transposon insertion mutant with an altered Maf1 expression profile, we demonstrated that proper Maf1 expression is necessary for survival of the dormancy-like state induced by prolonged amino acid starvation and is needed for full recovery from other stresses that slow or stall the parasite cell cycle. This Maf1 mutant is defective in the downregulation of pre-tRNA synthesis under nutrient-limiting conditions, indicating that the function of Maf1 as a stress-responsive regulator of structural RNA transcription is conserved in P. falciparum. Recent work has demonstrated that parasites carrying artemisinin-resistant K13 alleles display an enhanced ability to recover from drug-induced growth retardation. We show that one such artemisinin-resistant line displays greater regulation of pre-tRNA expression and higher survival upon prolonged amino acid starvation, suggesting that overlapping, PfMaf1-associated pathways may regulate growth recovery from both artemisinin treatment and amino acid starvation. PMID:28351924

  13. Expression and characterisation of plasmepsin I from Plasmodium falciparum.

    PubMed

    Moon, R P; Tyas, L; Certa, U; Rupp, K; Bur, D; Jacquet, C; Matile, H; Loetscher, H; Grueninger-Leitch, F; Kay, J; Dunn, B M; Berry, C; Ridley, R G

    1997-03-01

    Two aspartic proteinases, plasmepsins I and II, are present in the digestive vacuole of the human malarial parasite Plasmodium falciparum and are believed to be essential for parasite degradation of haemoglobin. Here we report the expression and kinetic characterisation of functional recombinant plasmepsin I. In order to generate active plasmepsin I from its precursor, an autocatalytic cleavage site was introduced into the propart of the zymogen by mutation of Lys110P to Val (P indicates a propart residue). Appropriate refolding of the mutated zymogen then permitted pH-dependent autocatalytic processing of the zymogen to the active mature proteinase. A purification scheme was devised that removed aggregated and misfolded protein to yield pure, fully processable, proplasmepsin I. Kinetic constants for two synthetic peptide substrates and four inhibitors were determined for both recombinant plasmepsin I and recombinant plasmepsin II. Plasmepsin I had 5-10-fold lower k(cat)/Km values than plasmepsin II for the peptide substrates, while the aspartic proteinase inhibitors, selected for their ability to inhibit P. falciparum growth, were found to have up to 80-fold lower inhibition constants for plasmepsin I compared to plasmepsin II. The most active plasmepsin I inhibitors were antagonistic to the antimalarial action of chloroquine on cultured parasites. Northern blot analysis of RNA, isolated from specific stages of the erythrocytic cycle of P. falciparum, showed that the proplasmepsin I gene is expressed in the ring stages whereas the proplasmepsin II gene is not transcribed until the later trophozoite stage of parasite growth. The differences in kinetic properties and temporal expression of the two plasmepsins suggest they are not functionally redundant but play distinct roles in the parasite.

  14. Amodiaquine failure associated with erythrocytic glutathione in Plasmodium falciparum malaria

    PubMed Central

    Zuluaga, Lina; Pabón, Adriana; López, Carlos; Ochoa, Aleida; Blair, Silvia

    2007-01-01

    Objective To establish the relationship between production of glutathione and the therapeutic response to amodiaquine (AQ) monotherapy in Plasmodium falciparum non-complicated malaria patients. Methodology Therapeutic response to AQ was evaluated in 32 patients with falciparum malaria in two townships of Antioquia, Colombia, and followed-up for 28 days. For every patient, total glutathione and enzymatic activity (glutathione reductase, GR, and γ-glutamylcysteine synthetase, γ-GCS) were determined in parasitized erythrocytes, non-infected erythrocytes and free parasites, on the starting day (day zero, before ingestion of AQ) and on the day of failure (in case of occurrence). Results There was found an AQ failure of 31.25%. Independent of the therapeutic response, on the starting day and on the day of failure, lower total glutathione concentration and higher GR activities in parasitized erythrocytes were found, compared with non-infected erythrocytes (p < 0.003). In addition, only on the day of failure, γ-GCS activity of parasitized erythrocytes was higher, compared with that of healthy erythrocytes (p = 0.01). Parasitized and non-parasitized erythrocytes in therapeutic failure patients (TF) had higher total glutathione on the starting day compared with those of adequate clinical response (ACR) (p < 0.02). Parasitized erythrocytes of TF patients showed lower total glutathione on the failure day, compared with starting day (p = 0.017). No differences was seen in the GR and γ-GCS activities by compartment, neither between the two therapeutic response groups nor between the two treatment days. Conclusion This study is a first approach to explaining P. falciparum therapeutic failure in humans through differences in glutathione metabolism in TF and ACR patients. These results suggest a role for glutathione in the therapeutic failure to antimalarials. PMID:17451604

  15. Malaria vaccines: identifying Plasmodium falciparum liver-stage targets

    PubMed Central

    Longley, Rhea J.; Hill, Adrian V. S.; Spencer, Alexandra J.

    2015-01-01

    The development of a highly efficacious and durable vaccine for malaria remains a top priority for global health researchers. Despite the huge rise in recognition of malaria as a global health problem and the concurrent rise in funding over the past 10–15 years, malaria continues to remain a widespread burden. The evidence of increasing resistance to anti-malarial drugs and insecticides is a growing concern. Hence, an efficacious and durable preventative vaccine for malaria is urgently needed. Vaccines are one of the most cost-effective tools and have successfully been used in the prevention and control of many diseases, however, the development of a vaccine for the Plasmodium parasite has proved difficult. Given the early success of whole sporozoite mosquito-bite delivered vaccination strategies, we know that a vaccine for malaria is an achievable goal, with sub-unit vaccines holding great promise as they are simple and cheap to both manufacture and deploy. However a major difficulty in development of sub-unit vaccines lies within choosing the appropriate antigenic target from the 5000 or so genes expressed by the parasite. Given the liver-stage of malaria represents a bottle-neck in the parasite’s life cycle, there is widespread agreement that a multi-component sub-unit malaria vaccine should preferably contain a liver-stage target. In this article we review progress in identifying and screening Plasmodium falciparum liver-stage targets for use in a malaria vaccine. PMID:26441899

  16. [Acute renal failure and Plasmodium falciparum malaria: a case report].

    PubMed

    Kissou, S A; Cessouma, R; Barro, M; Traoré, H; Nacro, B

    2012-01-01

    Malaria is an endemic disease caused by one of the several Plasmodium species. Severe malaria is mainly due to Plasmodium falciparum in highly endemic areas. Acute renal failure (ARF) is a criterion of malaria severity as defined by WHO. Often observed in adults, particularly in India and Southeast Asia, this complication remains a rare complication of malaria in children. We report a case of oliguric ARF that occurred in a 7-year-old girl a few days after the onset of fever. The vascular obstruction by parasitized erythrocytes often causing tubular necrosis is the primary mechanism of renal failure. As a possible diagnosis, hemolytic uremic syndrome, renal failure and quartan hemoglobinuric nephropathy are other possible causes of renal failure in malaria. Renal biopsy, which was not performed in our patient, would have been a great help, but was not available. The outcome was favorable with recovery of renal function after 3 weeks of diuretic therapy. This development is not always the rule and the prognosis depends on early diagnosis and treatment options.

  17. Epigenetic Silencing of Plasmodium falciparum Genes Linked to Erythrocyte Invasion

    PubMed Central

    Cortés, Alfred; Carret, Celine; Kaneko, Osamu; Yim Lim, Brian Y. S.; Ivens, Alasdair; Holder, Anthony A

    2007-01-01

    The process of erythrocyte invasion by merozoites of Plasmodium falciparum involves multiple steps, including the formation of a moving junction between parasite and host cell, and it is characterised by the redundancy of many of the receptor–ligand interactions involved. Several parasite proteins that interact with erythrocyte receptors or participate in other steps of invasion are encoded by small subtelomerically located gene families of four to seven members. We report here that members of the eba, rhoph1/clag, acbp, and pfRh multigene families exist in either an active or a silenced state. In the case of two members of the rhoph1/clag family, clag3.1 and clag3.2, expression was mutually exclusive. Silencing was clonally transmitted and occurred in the absence of detectable DNA alterations, suggesting that it is epigenetic. This was demonstrated for eba-140. Our data demonstrate that variant or mutually exclusive expression and epigenetic silencing in Plasmodium are not unique to genes such as var, which encode proteins that are exported to the surface of the erythrocyte, but also occur for genes involved in host cell invasion. Clonal variant expression of invasion-related ligands increases the flexibility of the parasite to adapt to its human host. PMID:17676953

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

    PubMed Central

    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. Complement activation in Ghanaian children with severe Plasmodium falciparum malaria

    PubMed Central

    Helegbe, Gideon K; Goka, Bamenla Q; Kurtzhals, Joergen AL; Addae, Michael M; Ollaga, Edwin; Tetteh, John KA; Dodoo, Daniel; Ofori, Michael F; Obeng-Adjei, George; Hirayama, Kenji; Awandare, Gordon A; Akanmori, Bartholomew D

    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 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 < 0.001). DCT correlated significantly with RD (β = -304, p = 0.006), but multiple regression analysis revealed that, Hb (β = -0.341, p = 0.012) and coma (β = -0.256, p = 0.034) were stronger predictors of RD than DCT (β = 0.228, p = 0.061). DCT was also not associated with IVH, p = 0.19, while spleen size was inversely correlated with Hb (r = -402, p = 0.001). Flow cytometry showed similar mean fluorescent intensity (MFI) values of CD35, CD55 and C3bαβ levels on the surfaces of RBC in patients and asymptomatic controls (AC). However, binding of C3bαβ correlated significantly with CD35 or CD55 (p < 0.001). Conclusion These results suggest that complement activation contributed to anaemia in acute childhood P. falciparum malaria, possibly through induction of erythrophagocytosis and haemolysis. In

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

    PubMed

    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

    2009-03-24

    Efficient allocation of resources to intervene against malaria requires a detailed understanding of the contemporary spatial distribution of malaria risk. It is exactly 40 y since the last global map of malaria endemicity was published. This paper describes the generation of a new world map of Plasmodium falciparum malaria endemicity for the year 2007. A total of 8,938 P. falciparum parasite rate (PfPR) surveys were identified using a variety of exhaustive search strategies. Of these, 7,953 passed strict data fidelity tests for inclusion into a global database of PfPR data, age-standardized to 2-10 y for endemicity mapping. A model-based geostatistical procedure was used to create a continuous surface of malaria endemicity within previously defined stable spatial limits of P. falciparum transmission. These procedures were implemented within a Bayesian statistical framework so that the uncertainty of these predictions could be evaluated robustly. The uncertainty was expressed as the probability of predicting correctly one of three endemicity classes; previously stratified to be an informative guide for malaria control. Population at risk estimates, adjusted for the transmission modifying effects of urbanization in Africa, were then derived with reference to human population surfaces in 2007. Of the 1.38 billion people at risk of stable P. falciparum malaria, 0.69 billion were found in Central and South East Asia (CSE Asia), 0.66 billion in Africa, Yemen, and Saudi Arabia (Africa+), and 0.04 billion in the Americas. All those exposed to stable risk in the Americas were in the lowest endemicity class (PfPR2-10 < or = 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 > or = 40%) areas. High endemicity was widespread in the Africa+ region, where 0

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

    PubMed Central

    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

  2. Origin and evolution of sulfadoxine resistant Plasmodium falciparum.

    PubMed

    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.

  3. Origin and Evolution of Sulfadoxine Resistant Plasmodium falciparum

    PubMed Central

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

    2010-01-01

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

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

    PubMed Central

    2012-01-01

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

  5. Antimalarials increase vesicle pH in Plasmodium falciparum

    PubMed Central

    1985-01-01

    The asexual erythrocytic stage of the malarial parasite ingests and degrades the hemoglobin of its host red cell. To study this process, we labeled the cytoplasm of uninfected red cells with fluorescein-dextran, infected those cells with trophozoite- and schizont-rich cultures of Plasmodium falciparum, and harvested them 110-120 h later in the trophozoite stage. After lysis of the red cell cytoplasm with digitonin, the only fluorescence remaining was in small (0.5-0.9 micron) vesicles similar to the parasite's food vacuole. As measured by spectrofluorimetry, the pH of these vesicles was acid (initial pH 5.2- 5.4), and they responded to MgATP with acidification and to weak bases such as NH4Cl with alkalinization. These three properties are similar to those obtained with human fibroblasts and suggest that the endocytic vesicles of plasmodia are similar to those of mammalian cells. Each of the antimalarials tested (chloroquine, quinine, and mefloquine) as well as NH4Cl inhibited parasite growth at concentrations virtually identical to those that increased parasite vesicle pH. These results suggest two conclusions: (a) The increases in vesicle pH that we have observed in our digitonin-treated parasite preparation occur at similar concentrations of weak bases and antimalarials in cultures of parasitized erythrocytes, and (b) P. falciparum parasites are exquisitely dependent on vesicle pH during their asexual erythrocytic cycle, perhaps for processes analogous to endocytosis and proteolysis in mammalian cells, and that antimalarials and NH4Cl may act by interfering with these events. PMID:3905824

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

    PubMed

    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.

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

    PubMed

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

    2015-04-30

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

  8. Fitness of artemisinin-resistant Plasmodium falciparum in vitro

    PubMed Central

    Hott, Amanda; Tucker, Matthew S.; Casandra, Debora; Sparks, Kansas; Kyle, Dennis E.

    2015-01-01

    Objectives Drug resistance confers a fitness advantage to parasites exposed to frequent drug pressure, yet these mutations also may incur a fitness cost. We assessed fitness advantages and costs of artemisinin resistance in Plasmodium falciparum in vitro to understand how drug resistance will spread and evolve in a competitive environment. Methods Genotyping of SNPs, drug susceptibility assays and copy number determination were used to assess the impact of artemisinin resistance on parasite fitness. An artemisinin-resistant clone (C9) selected in vitro from an isogenic parental clone (D6) was used to conduct competitive growth studies to assess fitness of artemisinin resistance. The resistant and susceptible clones were mixed or grown alone in the presence and absence of drug pressure (dihydroartemisinin or pyrimethamine) to quantify the rate at which artemisinin resistance was gained or lost. Results We experimentally demonstrate for the first time that artemisinin resistance provides a fitness advantage that is selected for with infrequent exposure to drug, but is lost in the absence of exposure to artemisinin drugs. The best correlations with artemisinin resistance were decreased in vitro drug susceptibility to artemisinin derivatives, increased copy number of Pf3D7_1030100 and an SNP in Pf3D7_0307600. An SNP conferring an E208K mutation in the kelch gene (Pf3D7_1343700) was not associated with resistance. Furthermore, we observed second-cycle ring-stage dormancy induced by pyrimethamine, suggesting that dormancy is a fitness trait that provides an advantage for survival from antimalarial drug stress. Conclusions Artemisinin-resistant P. falciparum have a fitness advantage to survive and predominate in the population even in the face of infrequent exposure to artemisinin drugs. PMID:26203183

  9. A Worldwide Map of Plasmodium falciparum K13-Propeller Polymorphisms.

    PubMed

    Ménard, Didier; Khim, Nimol; Beghain, Johann; Adegnika, Ayola A; Shafiul-Alam, Mohammad; Amodu, Olukemi; Rahim-Awab, Ghulam; Barnadas, Céline; Berry, Antoine; Boum, Yap; Bustos, Maria D; Cao, Jun; Chen, Jun-Hu; Collet, Louis; Cui, Liwang; Thakur, Garib-Das; Dieye, Alioune; Djallé, Djibrine; Dorkenoo, Monique A; Eboumbou-Moukoko, Carole E; Espino, Fe-Esperanza-Caridad J; Fandeur, Thierry; Ferreira-da-Cruz, Maria-Fatima; Fola, Abebe A; Fuehrer, Hans-Peter; Hassan, Abdillahi M; Herrera, Socrates; Hongvanthong, Bouasy; Houzé, Sandrine; Ibrahim, Maman L; Jahirul-Karim, Mohammad; Jiang, Lubin; Kano, Shigeyuki; Ali-Khan, Wasif; Khanthavong, Maniphone; Kremsner, Peter G; Lacerda, Marcus; Leang, Rithea; Leelawong, Mindy; Li, Mei; Lin, Khin; Mazarati, Jean-Baptiste; Ménard, Sandie; Morlais, Isabelle; Muhindo-Mavoko, Hypolite; Musset, Lise; Na-Bangchang, Kesara; Nambozi, Michael; Niaré, Karamoko; Noedl, Harald; Ouédraogo, Jean-Bosco; Pillai, Dylan R; Pradines, Bruno; Quang-Phuc, Bui; Ramharter, Michael; Randrianarivelojosia, Milijaona; Sattabongkot, Jetsumon; Sheikh-Omar, Abdiqani; Silué, Kigbafori D; Sirima, Sodiomon B; Sutherland, Colin; Syafruddin, Din; Tahar, Rachida; Tang, Lin-Hua; Touré, Offianan A; Tshibangu-wa-Tshibangu, Patrick; Vigan-Womas, Inès; Warsame, Marian; Wini, Lyndes; Zakeri, Sedigheh; Kim, Saorin; Eam, Rotha; Berne, Laura; Khean, Chanra; Chy, Sophy; Ken, Malen; Loch, Kaknika; Canier, Lydie; Duru, Valentine; Legrand, Eric; Barale, Jean-Christophe; Stokes, Barbara; Straimer, Judith; Witkowski, Benoit; Fidock, David A; Rogier, Christophe; Ringwald, Pascal; Ariey, Frederic; Mercereau-Puijalon, Odile

    2016-06-23

    Recent gains in reducing the global burden of malaria are threatened by the emergence of Plasmodium falciparum resistance to artemisinins. The discovery that mutations in portions of a P. falciparum gene encoding kelch (K13)-propeller domains are the major determinant of resistance has provided opportunities for monitoring such resistance on a global scale. We analyzed the K13-propeller sequence polymorphism in 14,037 samples collected in 59 countries in which malaria is endemic. Most of the samples (84.5%) were obtained from patients who were treated at sentinel sites used for nationwide surveillance of antimalarial resistance. We evaluated the emergence and dissemination of mutations by haplotyping neighboring loci. We identified 108 nonsynonymous K13 mutations, which showed marked geographic disparity in their frequency and distribution. In Asia, 36.5% of the K13 mutations were distributed within two areas--one in Cambodia, Vietnam, and Laos and the other in western Thailand, Myanmar, and China--with no overlap. In Africa, we observed a broad array of rare nonsynonymous mutations that were not associated with delayed parasite clearance. The gene-edited Dd2 transgenic line with the A578S mutation, which expresses the most frequently observed African allele, was found to be susceptible to artemisinin in vitro on a ring-stage survival assay. No evidence of artemisinin resistance was found outside Southeast Asia and China, where resistance-associated K13 mutations were confined. The common African A578S allele was not associated with clinical or in vitro resistance to artemisinin, and many African mutations appear to be neutral. (Funded by Institut Pasteur Paris and others.).

  10. Targeting the gyrase of Plasmodium falciparum with topoisomerase poisons.

    PubMed

    Tang Girdwood, Sonya C; Nenortas, Elizabeth; Shapiro, Theresa A

    2015-06-15

    Drug-resistant malaria poses a major public health problem throughout the world and the need for new antimalarial drugs is growing. The apicoplast, a chloroplast-like organelle essential for malaria parasite survival and with no counterpart in humans, offers an attractive target for selectively toxic new therapies. The apicoplast genome (plDNA) is a 35 kb circular DNA that is served by gyrase, a prokaryotic type II topoisomerase. Gyrase is poisoned by fluoroquinolone antibacterials that stabilize a catalytically inert ternary complex of enzyme, its plDNA substrate, and inhibitor. We used fluoroquinolones to study the gyrase and plDNA of Plasmodium falciparum. New methods for isolating and separating plDNA reveal four topologically different forms and permit a quantitative exam of perturbations that result from gyrase poisoning. In keeping with its role in DNA replication, gyrase is most abundant in late stages of the parasite lifecycle, but several lines of evidence indicate that even in these cells the enzyme is present in relatively low abundance: about 1 enzyme for every two plDNAs or a ratio of 1 gyrase: 70 kb DNA. For a spectrum of quinolones, correlation was generally good between antimalarial activity and gyrase poisoning, the putative molecular mechanism of drug action. However, in P. falciparum there is evidence for off-target toxicity, particularly for ciprofloxacin. These studies highlight the utility of the new methods and of fluoroquinolones as a tool for studying the in situ workings of gyrase and its plDNA substrate. Copyright © 2015 Elsevier Inc. All rights reserved.

  11. Purification and characterization of Plasmodium falciparum succinate dehydrogenase.

    PubMed

    Suraveratum, N; Krungkrai, S R; Leangaramgul, P; Prapunwattana, P; Krungkrai, J

    2000-02-05

    Succinate dehydrogenase (SDH), a Krebs cycle enzyme and complex II of the mitochondrial electron transport system was purified to near homogeneity from the human malarial parasite Plasmodium falciparum cultivated in vitro by FPLC on Mono Q, Mono S and Superose 6 gel filtration columns. The malarial SDH activity was found to be extremely labile. Based on Superose 6 FPLC, sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) and nondenaturing-PAGE analyses, it was demonstrated that the malarial enzyme had an apparent native molecular mass of 90 +/- 8 kDa and contained two major subunits with molecular masses of 55 +/- 6 and 35 +/- 4 kDa (n = 8). The enzymatic reaction required both succinate and coenzyme Q (CoQ) for its maximal catalysis with Km values of 3 and 0.2 microM, and k(cat) values of 0.11 and 0.06 min(-1), respectively. Catalytic efficiency of the malarial SDH for both substrates were found to be relatively low (approximately 600-5000 M(-1) s(-1)). Fumarate, malonate and oxaloacetate were found to inhibit the malarial enzyme with Ki values of 81, 13 and 12 microM, respectively. The malarial enzyme activity was also inhibited by substrate analog of CoQ, 5-hydroxy-2-methyl-1,4-naphthoquinone, with a 50% inhibitory concentration of 5 microM. The quinone had antimalarial activity against the in vitro growth of P. falciparum with a 50% inhibitory concentration of 0.27 microM and was found to completely inhibit oxygen uptake of the parasite at a concentration of 0.88 microM. A known inhibitor of mammalian mitochondrial SDH, 2-thenoyltrifluoroacetone. had no inhibitory effect on both the malarial SDH activity and the oxygen uptake of the parasite at a concentration of 50 microM. Many properties observed in the malarial SDH were found to be different from the host mammalian enzyme.

  12. A Worldwide Map of Plasmodium falciparum K13-Propeller Polymorphisms

    PubMed Central

    Ménard, D.; Khim, N.; Beghain, J.; Adegnika, A.A.; Shafiul-Alam, M.; Amodu, O.; Rahim-Awab, G.; Barnadas, C.; Berry, A.; Boum, Y.; Bustos, M.D.; Cao, J.; Chen, J.-H.; Collet, L.; Cui, L.; Thakur, G.-D.; Dieye, A.; Djallé, D.; Dorkenoo, M.A.; Eboumbou-Moukoko, C.E.; Espino, F.-E.-C.J.; Fandeur, T.; Ferreira-da-Cruz, M.-F.; Fola, A.A.; Fuehrer, H.-P.; Hassan, A.M.; Herrera, S.; Hongvanthong, B.; Houzé, S.; Ibrahim, M.L.; Jahirul-Karim, M.; Jiang, L.; Kano, S.; Ali-Khan, W.; Khanthavong, M.; Kremsner, P.G.; Lacerda, M.; Leang, R.; Leelawong, M.; Li, M.; Lin, K.; Mazarati, J.-B.; Ménard, S.; Morlais, I.; Muhindo-Mavoko, H.; Musset, L.; Na-Bangchang, K.; Nambozi, M.; Niaré, K.; Noedl, H.; Ouédraogo, J.-B.; Pillai, D.R.; Pradines, B.; Quang-Phuc, B.; Ramharter, M.; Randrianarivelojosia, M.; Sattabongkot, J.; Sheikh-Omar, A.; Silué, K.D.; Sirima, S.B.; Sutherland, C.; Syafruddin, D.; Tahar, R.; Tang, L.-H.; Touré, O.A.; Tshibangu-wa-Tshibangu, P.; Vigan-Womas, I.; Warsame, M.; Wini, L.; Zakeri, S.; Kim, S.; Eam, R.; Berne, L.; Khean, C.; Chy, S.; Ken, M.; Loch, K.; Canier, L.; Duru, V.; Legrand, E.; Barale, J.-C.; Stokes, B.; Straimer, J.; Witkowski, B.; Fidock, D.A.; Rogier, C.; Ringwald, P.; Ariey, F.; Mercereau-Puijalon, O.

    2016-01-01

    BACKGROUND Recent gains in reducing the global burden of malaria are threatened by the emergence of Plasmodium falciparum resistance to artemisinins. The discovery that mutations in portions of a P. falciparum gene encoding kelch (K13)–propeller domains are the major determinant of resistance has provided opportunities for monitoring such resistance on a global scale. METHODS We analyzed the K13-propeller sequence polymorphism in 14,037 samples collected in 59 countries in which malaria is endemic. Most of the samples (84.5%) were obtained from patients who were treated at sentinel sites used for nationwide surveillance of antimalarial resistance. We evaluated the emergence and dissemination of mutations by haplotyping neighboring loci. RESULTS We identified 108 nonsynonymous K13 mutations, which showed marked geographic disparity in their frequency and distribution. In Asia, 36.5% of the K13 mutations were distributed within two areas — one in Cambodia, Vietnam, and Laos and the other in western Thailand, Myanmar, and China — with no overlap. In Africa, we observed a broad array of rare nonsynonymous mutations that were not associated with delayed parasite clearance. The gene-edited Dd2 transgenic line with the A578S mutation, which expresses the most frequently observed African allele, was found to be susceptible to artemisinin in vitro on a ring-stage survival assay. CONCLUSIONS No evidence of artemisinin resistance was found outside Southeast Asia and China, where resistance-associated K13 mutations were confined. The common African A578S allele was not associated with clinical or in vitro resistance to artemisinin, and many African mutations appear to be neutral. PMID:27332904

  13. Spatial prediction of Plasmodium falciparum prevalence in Somalia

    PubMed Central

    Noor, Abdisalan M; Clements, Archie CA; Gething, Peter W; Moloney, Grainne; Borle, Mohammed; Shewchuk, Tanya; Hay, Simon I; Snow, Robert W

    2008-01-01

    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 < 5%; areas with ≥ 5% prevalence were predominantly in the south. 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. PMID:18717998

  14. Characterisation of exogenous folate transport in Plasmodium falciparum

    PubMed Central

    Wang, Ping; Wang, Qi; Sims, Paul F.G.; Hyde, John E.

    2007-01-01

    Folate salvage by Plasmodium falciparum is an important source of key cofactors, but little is known about the underlying mechanism. Using synchronised parasite cultures, we observed that uptake of this dianionic species against the negative-inward electrochemical gradient is highly dependent upon cell-cycle stage, temperature and pH, but not on mono- or divalent metal ions. Energy dependence was tested with different sugars; glucose was necessary for folate import, although fructose was also able to function in this role, unlike sugars that cannot be processed through the glycolytic pathway. Import into both infected erythrocytes and free parasites was strongly inhibited by the anion-channel blockers probenecid and furosemide, which are likely to be acting predominantly on specific folate transporters in both cases. Import was not affected by high concentrations of the antifolate drugs pyrimethamine and sulfadoxine, but was inhibited by the close folate analogue methotrexate. The pH optimum for folate uptake into infected erythrocytes was 6.5–7.0. Dinitrophenol and nigericin, which strongly facilitate the equilibration of H+ ions across biological membranes and thus abolish or substantially reduce the proton gradient, inhibited folate uptake profoundly. The ATPase inhibitor concanamycin A also greatly reduced folate uptake, further demonstrating a link to ATP-powered proton transport. These data strongly suggest that the principal folate uptake pathway in P. falciparum is specific, highly regulated, dependent upon the proton gradient across the parasite plasma membrane, and is likely to be mediated by one or more proton symporters. PMID:17509698

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

    PubMed

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

    2017-05-02

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

  16. Spatial prediction of Plasmodium falciparum prevalence in Somalia.

    PubMed

    Noor, Abdisalan M; Clements, Archie C A; Gething, Peter W; Moloney, Grainne; Borle, Mohammed; Shewchuk, Tanya; Hay, Simon I; Snow, Robert W

    2008-08-21

    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. 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. 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 < 5%; areas with > or = 5% prevalence were predominantly in the south. 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.

  17. Calmidazolium evokes high calcium fluctuations in Plasmodium falciparum.

    PubMed

    Budu, Alexandre; Gomes, Mayrim M; Melo, Pollyana M; El Chamy Maluf, Sarah; Bagnaresi, Piero; Azevedo, Mauro F; Carmona, Adriana K; Gazarini, Marcos L

    2016-03-01

    Calcium and calmodulin (CaM) are important players in eukaryote cell signaling. In the present study, by using a knockin approach, we demonstrated the expression and localization of CaM in all erythrocytic stages of Plasmodium falciparum. Under extracellular Ca(2+)-free conditions, calmidazolium (CZ), a potent CaM inhibitor, promoted a transient cytosolic calcium ([Ca(2+)]cyt) increase in isolated trophozoites, indicating that CZ mobilizes intracellular sources of calcium. In the same extracellular Ca(2+)-free conditions, the [Ca(2+)]cyt rise elicited by CZ treatment was ~3.5 fold higher when the endoplasmic reticulum (ER) calcium store was previously depleted ruling out the mobilization of calcium from the ER by CZ. The effects of the Ca(2+)/H(+) ionophore ionomycin (ION) and the Na(+)/H(+) ionophore monensin (MON) suggest that the [Ca(2+)]cyt-increasing effect of CZ is driven by the removal of Ca(2+) from at least one Ca(2+)-CaM-related (CaMR) protein as well as by the mobilization of Ca(2+) from intracellular acidic calcium stores. Moreover, we showed that the mitochondrion participates in the sequestration of the cytosolic Ca(2+) elicited by CZ. Finally, the modulation of membrane Ca(2+) channels by CZ and thapsigargin (THG) was demonstrated. The opened channels were blocked by the unspecific calcium channel blocker Co(2+) but not by 2-APB (capacitative calcium entry inhibitor) or nifedipine (L-type Ca(2+) channel inhibitor). Taken together, the results suggested that one CaMR protein is an important modulator of calcium signaling and homeostasis during the Plasmodium intraerythrocytic cell cycle, working as a relevant intracellular Ca(2+) reservoir in the parasite. Copyright © 2015 Elsevier Inc. All rights reserved.

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

    PubMed

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

    2013-12-17

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

  19. In vitro adaptation of Plasmodium falciparum reveal variations in cultivability.

    PubMed

    White, John; Mascarenhas, Anjali; Pereira, Ligia; Dash, Rashmi; Walke, Jayashri T; Gawas, Pooja; Sharma, Ambika; Manoharan, Suresh Kumar; Guler, Jennifer L; Maki, Jennifer N; Kumar, Ashwani; Mahanta, Jagadish; Valecha, Neena; Dubhashi, Nagesh; Vaz, Marina; Gomes, Edwin; Chery, Laura; Rathod, Pradipsinh K

    2016-01-22

    Culture-adapted Plasmodium falciparum parasites can offer deeper understanding of geographic variations in drug resistance, pathogenesis and immune evasion. To help ground population-based calculations and inferences from culture-adapted parasites, the complete range of parasites from a study area must be well represented in any collection. To this end, standardized adaptation methods and determinants of successful in vitro adaption were sought. Venous blood was collected from 33 P. falciparum-infected individuals at Goa Medical College and Hospital (Bambolim, Goa, India). Culture variables such as whole blood versus washed blood, heat-inactivated plasma versus Albumax, and different starting haematocrit levels were tested on fresh blood samples from patients. In vitro adaptation was considered successful when two four-fold or greater increases in parasitaemia were observed within, at most, 33 days of attempted culture. Subsequently, parasites from the same patients, which were originally cryopreserved following blood draw, were retested for adaptability for 45 days using identical host red blood cells (RBCs) and culture media. At a new endemic area research site, ~65% of tested patient samples, with varied patient history and clinical presentation, were successfully culture-adapted immediately after blood collection. Cultures set up at 1% haematocrit and 0.5% Albumax adapted most rapidly, but no single test condition was uniformly fatal to culture adaptation. Success was not limited by low patient parasitaemia nor by patient age. Some parasites emerged even after significant delays in sample processing and even after initiation of treatment with anti-malarials. When 'day 0' cryopreserved samples were retested in parallel many months later using identical host RBCs and media, speed to adaptation appeared to be an intrinsic property of the parasites collected from individual patients. Culture adaptation of P. falciparum in a field setting is formally shown to be

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

    PubMed

    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

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

    PubMed Central

    Awasthi, Vikky; Verma, Kalpana; Sutton, Patrick; Ali, Syed Zeeshan; Patel, Ankita; G., Sri Lakshmi Priya; Ravishankaran, Sangamithra; Desai, Nisha; Tandel, Nikunj; Choubey, Sandhya; Barla, Punam; Kanagaraj, Deena; Eapen, Alex; Pradhan, Khageswar; Singh, Ranvir; Jain, Aarti; Felgner, Philip L.; Davies, D. Huw; Das, Jyoti

    2017-01-01

    Understanding naturally acquired immune responses to Plasmodium in India is key to improving malaria surveillance and diagnostic tools. Here we describe serological profiling of immune responses at three sites in India by probing protein microarrays consisting of 515 Plasmodium vivax and 500 Plasmodium falciparum proteins with 353 plasma samples. A total of 236 malaria-positive (symptomatic and asymptomatic) plasma samples and 117 malaria-negative samples were collected at three field sites in Raurkela, Nadiad, and Chennai. Indian samples showed significant seroreactivity to 265 P. vivax and 373 P. falciparum antigens, but overall seroreactivity to P. vivax antigens was lower compared to P. falciparum antigens. We identified the most immunogenic antigens of both Plasmodium species that were recognized at all three sites in India, as well as P. falciparum antigens that were associated with asymptomatic malaria. This is the first genome-scale analysis of serological responses to the two major species of malaria parasite in India. The range of immune responses characterized in different endemic settings argues for targeted surveillance approaches tailored to the diverse epidemiology of malaria across the world. PMID:28118367

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

    PubMed

    Uplekar, Swapna; Rao, Pavitra Nagesh; Ramanathapuram, Lalitha; Awasthi, Vikky; Verma, Kalpana; Sutton, Patrick; Ali, Syed Zeeshan; Patel, Ankita; G, Sri Lakshmi Priya; Ravishankaran, Sangamithra; Desai, Nisha; Tandel, Nikunj; Choubey, Sandhya; Barla, Punam; Kanagaraj, Deena; Eapen, Alex; Pradhan, Khageswar; Singh, Ranvir; Jain, Aarti; Felgner, Philip L; Davies, D Huw; Carlton, Jane M; Das, Jyoti

    2017-01-01

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

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

    PubMed

    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.

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

    PubMed Central

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

    2013-01-01

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

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

    PubMed

    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.

  6. Artemisinin-naphthoquine for treating uncomplicated Plasmodium falciparum malaria

    PubMed Central

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

    2015-01-01

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

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

    PubMed

    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.

  8. Chromosome End Repair and Genome Stability in Plasmodium falciparum

    PubMed Central

    Calhoun, Susannah F.; Reed, Jake; Alexander, Noah; Mason, Christopher E.; Deitsch, Kirk W.

    2017-01-01

    ABSTRACT The human malaria parasite Plasmodium falciparum replicates within circulating red blood cells, where it is subjected to conditions that frequently cause DNA damage. The repair of DNA double-stranded breaks (DSBs) is thought to rely almost exclusively on homologous recombination (HR), due to a lack of efficient nonhomologous end joining. However, given that the parasite is haploid during this stage of its life cycle, the mechanisms involved in maintaining genome stability are poorly understood. Of particular interest are the subtelomeric regions of the chromosomes, which contain the majority of the multicopy variant antigen-encoding genes responsible for virulence and disease severity. Here, we show that parasites utilize a competitive balance between de novo telomere addition, also called “telomere healing,” and HR to stabilize chromosome ends. Products of both repair pathways were observed in response to DSBs that occurred spontaneously during routine in vitro culture or resulted from experimentally induced DSBs, demonstrating that both pathways are active in repairing DSBs within subtelomeric regions and that the pathway utilized was determined by the DNA sequences immediately surrounding the break. In combination, these two repair pathways enable parasites to efficiently maintain chromosome stability while also contributing to the generation of genetic diversity. PMID:28790200

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

    NASA Astrophysics Data System (ADS)

    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.

  10. Effects of zinc-desferrioxamine on Plasmodium falciparum in culture.

    PubMed Central

    Chevion, M; Chuang, L; Golenser, J

    1995-01-01

    The zinc-desferrioxamine (Zn-DFO) complex is considered to be more permeative into parasitized erythrocytes than is the metal-free DFO. The former may penetrate the cell and exchange its bound zinc for ferric ions, rendering the iron unavailable for vital parasite functions. The effects of these compounds on the in vitro development of Plasmodium falciparum are compared. The results indicate that Zn-DFO is superior to DFO, especially at concentrations below 20 microM, as shown by decreased levels of hypoxanthine incorporation, lower levels of parasitemia, and interference with the life cycle of the parasite. At low concentrations, DFO even enhanced parasite growth. Such an enhancement was not observed following exposure to Zn-DFO. Experiments in which the compounds were removed from the cultures indicated that parasites treated with Zn-DFO are less likely to recover at a later stage. Since DFO has already been used in humans for the treatment of malaria, its complex with zinc, which is more effective in vitro, should also be examined in vivo. PMID:7486946

  11. In vitro activities of novel catecholate siderophores against Plasmodium falciparum.

    PubMed Central

    Pradines, B; Ramiandrasoa, F; Basco, L K; Bricard, L; Kunesch, G; Le Bras, J

    1996-01-01

    The activities of novel iron chelators, alone and in combination with chloroquine, quinine, or artemether, were evaluated in vitro against susceptible and resistant clones of Plasmodium falciparum with a semimicroassay system. N4-nonyl,N1,N8-bis(2,3-dihydroxybenzoyl) spermidine hydrobromide (compound 7) demonstrated the highest level of activity: 170 nM against a chloroquine-susceptible clone and 1 microM against a chloroquine-resistant clone (50% inhibitory concentrations). Compounds 6, 8, and 10 showed antimalarial activity with 50% inhibitory concentrations of about 1 microM. Compound 7 had no effect on the activities of chloroquine, quinine, and artemether against either clone, and compound 8 did not enhance the schizontocidal action of either chloroquine or quinine against the chloroquine-resistant clone. The incubation of compound 7 with FeCI3 suppressed or decreased the in vitro antimalarial activity of compound 7, while no effect was observed with incubation of compound 7 with CuSO4 and ZnSO4. These results suggest that iron deprivation may be the main mechanism of action of compound 7 against the malarial parasites. Chelator compounds 7 and 8 primarily affected trophozoite stages, probably by influencing the activity of ribonucleotide reductase, and thus inhibiting DNA synthesis. PMID:8878587

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

    PubMed Central

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

    2015-01-01

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

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

    PubMed

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

    2015-10-01

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

  14. The gene encoding topoisomerase II from Plasmodium falciparum.

    PubMed

    Cheesman, S; McAleese, S; Goman, M; Johnson, D; Horrocks, P; Ridley, R G; Kilbey, B J

    1994-07-11

    The gene for topoisomerase II has been isolated from genomic libraries of strain K1 of the human malarial parasite, Plasmodium falciparum. The sequence reveals an open reading frame of 4194 nucleotides which predicts a polypeptide of 1398 amino acids. There are apparently no introns. The sequence is present as a single copy which has an identity of 47.4% and a similarity of 65.4% with its human homologue. Sequences conserved in topoisomerase II from other species are present in Pftopoisomerase II but in addition it has two adjacent asparagine-rich insertions which are unique to it. We have also detected asparagine-rich regions in the gene for PfDNA polymerase alpha. The gene for Pftopoisomerase II has been localised to chromosome 14 and northern analysis reveals a transcript of 5.8 kb. Two independent antisera raised in mice against glutathione-S-transferase fusion proteins containing the amino terminal portion of the malarial protein detect a weak band on western blots at about 160kDa, the expected size of the protein. Use of the same antisera for immunofluorescence analysis suggests that the protein is present at all stages of intraerythrocytic growth of the parasite.

  15. Calcium regulation in the intraerythrocytic malaria parasite Plasmodium falciparum.

    PubMed

    Alleva, L M; Kirk, K

    2001-10-01

    The regulation of intracellular Ca(2+) in the intraerythrocytic form of the human malaria parasite, Plasmodium falciparum, was investigated using parasites 'isolated' from their host cells by saponin-permeabilisation of the erythrocyte membrane. The isolated parasites maintained tight control over their resting cytosolic Ca(2+) concentration which ranged from approximately 100 nM in the absence of extracellular Ca(2+) to approximately 700 nM in the presence of 1 mM extracellular Ca(2+). The parasite has two functionally discrete intracellular Ca(2+) stores. One is an 'endoplasmic reticulum (ER)-like' store, the other an 'acidic store'. The ER-like store was discharged by cyclopiazonic acid (CPA), an inhibitor of sarco/endoplasmic reticulum Ca(2+)-ATPases (SERCAs) of animal and plant cells, but not by thapsigargin (TG), a more specific inhibitor of SERCAs of animal cells. The acidic store was discharged by nigericin and by NH(4)(+). The amount of Ca(2+) in the ER-like store increased with increasing extracellular Ca(2+) concentration, whereas the amount of Ca(2+) in the acidic store did not. Ca(2+) released from the ER-like store by CPA was cleared from the parasite cytosol by uptake into the acidic store (over a range of extracellular Ca(2+) concentrations), consistent with the acidic store serving as a Ca(2+) reservoir within the intracellular parasite.

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

    PubMed Central

    Tatem, Andrew J.; Smith, David L.

    2010-01-01

    Calls for the eradication of malaria require the development of global and regional strategies based on a strong and consistent evidence base. Evidence from the previous global malaria eradication program and more recent transborder control campaigns have shown the importance of accounting for human movement in introducing infections 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 linked by relatively high levels of infection movements. The likely principal sources and destinations of imported cases in each region were also mapped. Results indicate that certain groups of countries, such as those in West Africa and central Asia are much more strongly connected by relatively high levels of population and infection movement than others. In contrast, countries such as Ethiopia and Myanmar display significantly greater isolation in terms of likely infection movements in and out. The mapping here of both communities of countries linked by likely higher levels of infection movement, and “natural” migration boundaries that display reduced movement of people and infections between regions has practical utility. These maps can inform the design of malaria elimination strategies by identifying regional communities of countries afforded protection from recolonization by surrounding regions of reduced migration. For more isolated countries, a nationally focused control or elimination program is likely to stand a better chance of success than those receiving high levels of visitors and migrants from high-transmission regions. PMID:20566870

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

    PubMed

    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.

  18. Synchronous culture of Plasmodium falciparum at high parasitemia levels.

    PubMed

    Radfar, Azar; Méndez, Darío; Moneriz, Carlos; Linares, María; Marín-García, Patricia; Puyet, Antonio; Diez, Amalia; Bautista, José M

    2009-01-01

    This protocol describes a method for preparing cultures of Plasmodium falciparum synchronized at any intraerythrocytic stage. Using this method, around 60% parasitized cells may be obtained. On the basis of Trager and Jensen's original continuous culture method, our approach relies on the use of fresh human blood not older than 2 weeks, a low hematocrit between 0.8 and 1.5%, a starting frozen inoculum of 10% ring-stage parasitemia, human serum replaced with AlbuMAX I and alternating sorbitol and Percoll synchronization methods to shorten the cycle window to 4-6 h and reduce sorbitol toxicity. From our synchronized high parasite density cultures, 3-5 ml of infected red blood cells can be obtained in 1 week, corresponding to 1.2 mg of total parasite protein per ml of harvested culture. On the basis of the variables parasitemia and packed cell volume, we provide an equation to accurately calculate the amount of complete medium required every 24 h corrected for the cycle stage and capacity of the culture flask. Ten days suffice to complete the protocol from a frozen stock of parasites.

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

    PubMed Central

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

    2016-01-01

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

  20. Molecular and structural insight into plasmodium falciparum RIO2 kinase.

    PubMed

    Chouhan, Devendra K; Sharon, Ashoke; Bal, Chandralata

    2013-02-01

    Among approximately 65 kinases of the malarial genome, RIO2 (right open reading frame) kinase belonging to the atypical class of kinase is unique because along with a kinase domain, it has a highly conserved N-terminal winged helix (wHTH) domain. The wHTH domain resembles the wing like domain found in DNA binding proteins and is situated near to the kinase domain. Ligand binding to this domain may reposition the kinase domain leading to inhibition of enzyme function and could be utilized as a novel allosteric site to design inhibitor. In the present study, we have generated a model of RIO2 kinase from Plasmodium falciparum utilizing multiple modeling, simulation approach. A novel putative DNA-binding site is identified for the first time in PfRIO2 kinase to understand the DNA binding events involving wHTH domain and flexible loop. Induced fit DNA docking followed by minimization, molecular dynamics simulation, energetic scoring and binding mode studies are used to reveal the structural basis of PfRIO2-ATP-DNA complex. Ser105 as a potential site of phosphorylation is revealed through the structural studies of ATP binding in PfRIO2. Overall the present study discloses the structural facets of unknown PfRIO2 complex and opens an avenue toward exploration of novel drug target.

  1. Plasmodium falciparum heat shock protein 70 lacks immune modulatory activity.

    PubMed

    Pooe, Ofentse Jacob; Köllisch, Gabriele; Heine, Holger; Shonhai, Addmore

    2017-02-14

    Heat shock protein 70 (Hsp70) family are conserved molecules that constitute a major part of the cell's protein folding machinery. The role of Hsp70s of parasitic origin in host cell immune modulation has remained contentious. This is largely due to the fact that several studies implicating Hsp70 in immune modulation rely on the use of recombinant protein derived from bacteria which is often fraught contamination. Thus, in the current study, we expressed recombinant Plasmodium falciparum Hsp70 (PfHsp70) using in three bacterial expression hosts: E. coli XL1 Blue, E. coli ClearColi BL21 and Brevibacillus choshinensis, respectively. We further investigated the immunostimulatory capability of the protein by assessing cytokine production by murine immune cells cultured in the presence of the protein. Recombinant PfHsp70 obtained from E. coli XL1 Blue expression host induced IL6 and IL8 cytokines. On the other hand, PfHsp70 produced in E. coli ClearColi and B. choshinensis expression systems was associated with no detectable traces of LPS and exhibited no immunomodulatory activity. Our findings suggest that PfHsp70 does not possess immunomodulatory function. Furthermore, our study suggests that E. coli ClearColi and B. choshinensis are versatile for the production of recombinant protein for use in immunomodulatory studies.

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

    PubMed

    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

    2014-01-02

    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.

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

    PubMed Central

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

    2012-01-01

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

  4. Genetic architecture of artemisinin-resistant Plasmodium falciparum

    PubMed Central

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

    2015-01-01

    We report a large multicenter genome-wide association study of Plasmodium falciparum resistance to artemisinin, the frontline antimalarial drug. Across 15 locations in Southeast Asia, we identified at least 20 mutations in kelch13 (PF3D7_1343700) affecting the encoded propeller and BTB/POZ domains, which were associated with a slow parasite clearance rate after treatment with artemisinin derivatives. Nonsynonymous polymorphisms in fd (ferredoxin), arps10 (apicoplast ribosomal protein S10), mdr2 (multidrug resistance protein 2) and crt (chloroquine resistance transporter) also showed strong associations with artemisinin resistance. Analysis of the fine structure of the parasite population showed that the fd, arps10, mdr2 and crt polymorphisms are markers of a genetic background on which kelch13 mutations are particularly likely to arise and that they correlate with the contemporary geographical boundaries and population frequencies of artemisinin resistance. These findings indicate that the risk of new resistance-causing mutations emerging is determined by specific predisposing genetic factors in the underlying parasite population. PMID:25599401

  5. Recombination Hotspots and Population Structure in Plasmodium falciparum

    PubMed Central

    Mu, Jianbing; Duan, Junhui; McGee, Kate M; Joy, Deirdre A; McVean, Gilean A. T

    2005-01-01

    Understanding the influences of population structure, selection, and recombination on polymorphism and linkage disequilibrium (LD) is integral to mapping genes contributing to drug resistance or virulence in Plasmodium falciparum. The parasite's short generation time, coupled with a high cross-over rate, can cause rapid LD break-down. However, observations of low genetic variation have led to suggestions of effective clonality: selfing, population admixture, and selection may preserve LD in populations. Indeed, extensive LD surrounding drug-resistant genes has been observed, indicating that recombination and selection play important roles in shaping recent parasite genome evolution. These studies, however, provide only limited information about haplotype variation at local scales. Here we describe the first (to our knowledge) chromosome-wide SNP haplotype and population recombination maps for a global collection of malaria parasites, including the 3D7 isolate, whose genome has been sequenced previously. The parasites are clustered according to continental origin, but alternative groupings were obtained using SNPs at 37 putative transporter genes that are potentially under selection. Geographic isolation and highly variable multiple infection rates are the major factors affecting haplotype structure. Variation in effective recombination rates is high, both among populations and along the chromosome, with recombination hotspots conserved among populations at chromosome ends. This study supports the feasibility of genome-wide association studies in some parasite populations. PMID:16144426

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

    PubMed

    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.

  7. Plasmodium falciparum dolichol phosphate mannose synthase represents a novel clade

    SciTech Connect

    Shams-Eldin, Hosam Santos de Macedo, Cristiana; Niehus, Sebastian; Dorn, Caroline; Kimmel, Juergen; Azzouz, Nahid; Schwarz, Ralph T.

    2008-06-06

    Dolichol phosphate mannose synthase (DPM) catalyzes the reaction between dolichol phosphate (Dol-P) and guanosine diphosphate mannose (GDP-Man) to form dolichol-phosphate-mannose (Dol-P-Man). This molecule acts as mannose donor for N-glycosylation and glycosylphosphatidylinositol (GPI) biosynthesis. The Plasmodium falciparum DPM1 (Pfdpm1) possesses a single predicted transmembrane region near the N-, but not the C-terminus. Here we show that the cloned Pfdpm1 gene failed to complement a Saccharomyces cerevisiae mutant indicating that the parasite gene does not belong to the baker's yeast group, as was previously assumed. Furthermore, Pfdpm1 was unable to complement a mouse mutant deficient in DPM but efficiently complements the Schizosaccharomyces pombe fission yeast mutant, indicating a difference between fission yeast and mammalian DPM genes. Therefore, we reanalyzed the hydrophobicity scales of all known DPMs and consequently reclassify the DPM clade into six major novel subgroups. Furthermore, we show that Pfdpm1 represents a unique enzyme among these subgroups.

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

    PubMed

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

    2006-03-01

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

  9. Qualitative and semiquantitative polymerase chain reaction to predict Plasmodium falciparum treatment failure.

    PubMed

    Kain, K C; Kyle, D E; Wongsrichanalai, C; Brown, A E; Webster, H K; Vanijanonta, S; Looareesuwan, S

    1994-12-01

    Multidrug-resistant falciparum malaria is increasing in most malaria-endemic areas. Rapid methods for predicting treatment failure would aid management and control of drug-resistant infections. In this study, Plasmodium falciparum DNA clearance was examined by qualitative and semiquantitative polymerase chain reaction (PCR). Thai patients with acute falciparum malaria were prospectively followed by light microscopy and by PCR of P. falciparum DNA eluted from filter paper blood samples. A 206-bp P. falciparum sequence was amplified and detected radiometrically and by high-performance liquid chromatography. Clearance of P. falciparum DNA was significantly delayed in treatment failures compared with that in successfully treated patients (P = .02). Semiquantitative PCR levels did not drop to < 50% of pretreatment levels until day 3 or later in treatment failures compared with day 1 or earlier for successfully treated parasitemia-matched controls (P = .005). These results suggest that qualitative and semiquantitative PCR may be useful as a method for monitoring response to therapy.

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

    PubMed

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

    2014-08-01

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

  11. Artesunate plus pyronaridine for treating uncomplicated Plasmodium falciparum malaria

    PubMed Central

    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

  12. Loop-Mediated Isothermal Amplification and LFD Combination for Detection of Plasmodium falciparum and Plasmodium vivax.

    PubMed

    Kongkasuriyachai, Darin; Yongkiettrakul, Suganya; Kiatpathomchai, Wansika; Arunrut, Narong

    2017-01-01

    Loop-mediated isothermal amplification (LAMP) has been used to detect several pathogens including malaria parasites from field and clinical samples. In this protocol, the malaria LAMP technology is developed to differentiate between Plasmodium falciparum (Pf) and Plasmodium vivax (Pv) species by targeting the dihydrofolate reductase thymidylate synthase (dhfr-ts) gene, a known target for the antifolate class of drugs such as Pyrimethamine. LAMP primer sets are designed and validated for species specific amplification. Additionally, specific probes help improve detection and visualization of the products when combined with lateral flow dipstick-based (LFD) detection. The protocols are further simplified to eliminate tedious sample preparation steps, such that crude lysis prepared simply by diluting few microliter (μL) of blood sample with distilled water is sufficient. The LAMP-LFD malaria dhfr-ts protocols are sensitive and can detect as little as 1 picogram (pg) of PfDNA and 1 nanogram (ng) of PvDNA, or a few microliters of crude lysate from infected blood samples (Yongkiettrakul et al., Parasitol Int 63: 777-784, 2014). These simplified steps not only reduce cost but also increase the potential for large application in the fields and clinical settings.

  13. Artemisinin-naphthoquine for treating uncomplicated Plasmodium falciparum malaria.

    PubMed

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

    2015-02-23

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

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

    PubMed

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

    2007-01-01

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

  15. Cytotoxic T Lymphocytes in Humans Exposed to Plasmodium Falciparum by Immunization or Natural Exposure

    DTIC Science & Technology

    1994-01-01

    Patarapotikul J, Beaudoin RL, Dubeaux C. Tartar A, Mercereau-Puijalon 0, Langsley G (1987) A liver-stage-specific antigen of Plasmodium falciparum...2 ,13 ; PNG4; BRAl G S PNG3 D Q C S GAM3; 3662,, 6,7 Q N 40610; 4191-9; GAM4; 4062 R A GAM5; 4063,9 A D In mice and humans, a peptide including amino...Exposed to Plasmodium falciparum 201 Alonso PL, Lindsay SW, Armstrong JR, Conteh M, Hill AG, David PH, Fegan G (1991) The effect of insecticide-treated

  16. Monitoring PfMDR1 transport in Plasmodium falciparum.

    PubMed

    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.

  17. Monoclonal antibody epitope mapping of Plasmodium falciparum rhoptry proteins.

    PubMed

    Sam-Yellowe, T Y; Ndengele, M M

    1993-02-01

    Plasmodium falciparum rhoptry proteins of the 140/130/110-kDa high molecular weight complex (HMWC) are secreted into the erythrocyte membrane during merozoite invasion. Epitopes of membrane-associated HMWC proteins can be detected using rhoptry-specific antibodies by immunofluorescence assays. Phospholipase treatment of ring-infected intact human erythrocytes, membrane ghosts, and inside-out vesicles results in the release of the HMWC as demonstrated by immunoblotting. We characterized the membrane-associating properties of the 110-kDa protein in more detail. PLA2 from three different sources; bee venom, Naja naja venom, and porcine pancreas, were examined and all were equally effective in releasing the 110-kDa protein. Furthermore, PLA2 activity was inhibited by o-phenanthroline, quinacrine, maleic anhydride, and partially by p-bromophenacyl bromide, indicating that the activity of PLA2 is specific. Using sequential protease and phospholipase digestion experiments to map the immunoreactive and functional epitopes of the 110-kDa protein, a 35-kDa protease-resistant protein associated with mouse and human erythrocyte membranes was identified. Limited proteolysis of the 110-kDa protein and analysis by immunoblotting demonstrated several immunoreactive cleavage products, including a highly protease-resistant peptide fragment of approximately 35-kDa which corresponds to the membrane-associated protein. Epitope mapping of the 130-kDa rhoptry protein resulted in a different pattern of cleavage products. Stage-specific metabolic labeling of P. falciparum with [3H] palmitate and [3H] myristate was performed to determine the lipophilic properties of the HMWC. Results showed the incorporation of label into proteins of approximate molecular weight 200 and 45-kDa, predominantly in the late schizont stage. Interestingly, proteins of 140 and 110/100-kDa, corresponding to [35S] methionine-labeled proteins were labeled with [3H]palmitate in ring-infected erythrocyte membranes

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

    PubMed

    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.

  19. Functional Analysis of Sirtuin Genes in Multiple Plasmodium falciparum Strains

    PubMed Central

    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. PMID:25780929

  20. Accelerated senescence of human erythrocytes cultured with Plasmodium falciparum.

    PubMed

    Omodeo-Salè, Fausta; Motti, Anna; Basilico, Nicoletta; Parapini, Silvia; Olliaro, Piero; Taramelli, Donatella

    2003-07-15

    Red blood cells infected withPlasmodium falciparum(IRBCs) undergo changes primarily in their membrane composition that contribute to malaria pathogenesis. However, all manifestations (eg, anemia) cannot be accounted for by IRBCs alone. Uninfected erythrocytes (URBCs) may play a role, but they have been under-researched. We wanted to document changes in the erythrocyte membrane that could contribute to URBC reduced life span and malaria-associated anemia. Human erythrocytes were cultured withP falciparumand washed at the trophozoite stage. IRBCs and URBCs were separated on Percoll density gradient, thus obtaining erythrocyte fractions of different densities/ages. IRBC- and URBC-purified membranes were analyzed and compared with control normal erythrocytes (NRBCs) of the same age, from the same donor, kept in the same conditions.P falciparumaccelerated aging of both IRBCs and URBCs, causing a significant shift in the cell population toward the denser (old) fraction. Protein, phospholipid, and cholesterol content were reduced in IRBCs and young URBCs. Young and medium uninfected fractions had higher levels of lipid peroxidation and phospholipid saturation (because of the loss of polyunsaturated fatty acids, PUFAs) and lower phosphatidylserine. In IRBCs, thiobarbituric reactive substances (TBARSs) were higher, and PUFAs and phosphatidylserine lower than in NRBCs and URBCs. In comparison, trophozoite membranes had lower phospholipid (particularly sphingomyelin and phosphatidylserine) and cholesterol content and a higher degree of saturation. Parasite-induced peroxidative damage might account for these modifications. In summary, we demonstrated that membrane damage leading to accelerated senescence of both infected and uninfected erythrocytes will likely contribute to malaria anemia.

  1. Prevalence of mutation and phenotypic expression associated with sulfadoxine-pyrimethamine resistance in Plasmodium falciparum and Plasmodium vivax.

    PubMed

    Zakai, Haytham A; Khan, Wajihullah; Asma, Umme

    2013-09-01

    Therapeutic efficacy of sulfadoxine-pyrimethamine (SP), which is commonly used to treat falciparum malaria, was assessed in isolates of Plasmodium falciparum (Welch, 1897) and Plasmodium vivax (Grassi et Feletti, 1890) ofAligarh, Uttar Pradesh, North India and Taif, Saudi Arabia during 2011-2012. Both the species showed mutations in dihydrofolate reductase (DHFR) enzyme as they have common biochemical drug targets. Mutation rate for pfdhfr was higher compared to pvdhfr because the drug was mainly given to treat falciparum malaria. Since both the species coexist, P. vivax was also exposed to SP due to faulty species diagnosis or medication without specific diagnosis. Low level of mutations against SP in P. falciparum of Saudi isolates indicates that the SP combination is still effective for the treatment of falciparum malaria. Since SP is used as first-line of treatment because of high level of resistance against chloroquine (CQ), it may result in spread of higher level of mutations resulting in drug resistance and treatment failure in near future. Therefore, to avoid further higher mutations in the parasite, use of better treatment regimens such as artesunate combination therapy must be introduced against SP combination.

  2. Host age as a determinant of naturally acquired immunity to Plasmodium falciparum.

    PubMed

    Baird, J K

    1995-03-01

    The usual course of infection by Plasmodium falciparum among adults who lack a history of exposure to endemic malaria is fulminant. The infection in adults living with hyper- to holoendemic malaria is chronic and benign. Naturally acquired immunity to falciparum malaria is the basis of this difference. Confusion surrounds an essential question regarding this process: What is its rate of onset? Opinions vary because of disagreement over the relationships between exposure to infection, antigenic polymorphism and naturally acquired immunity. In this review, Kevin Baird discusses these relationships against a backdrop of host age as a determinant of naturally acquired immunity to falciparum malaria.

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

    PubMed

    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.

  4. Predictors of Plasmodium falciparum Malaria Incidence in Chano Mille, South Ethiopia: A Longitudinal Study

    PubMed Central

    Loha, Eskindir; Lindtjørn, Bernt

    2012-01-01

    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. PMID:22826493

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

    PubMed

    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.

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

    PubMed

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

    2013-05-01

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

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

    PubMed Central

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

    1987-01-01

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

  8. Erythrocyte Lysis and Xenopus laevis Oocyte Rupture by Recombinant Plasmodium falciparum Hemolysin III

    PubMed Central

    Moonah, Shannon; Sanders, Natalie G.; Persichetti, Jason K.

    2014-01-01

    Malaria kills more than 1 million people per year worldwide, with severe malaria anemia accounting for the majority of the deaths. Malaria anemia is multifactorial in etiology, including infected erythrocyte destruction and decrease in erythrocyte production, as well as destruction or clearance of noninfected erythrocytes. We identified a panspecies Plasmodium hemolysin type III related to bacterial hemolysins. The identification of a hemolysin III homologue in Plasmodium suggests a potential role in host erythrocyte lysis. Here, we report the first characterization of Plasmodium falciparum hemolysin III, showing that the soluble recombinant P. falciparum hemolysin III is a pore-forming protein capable of lysing human erythrocytes in a dose-, time-, and temperature-dependent fashion. The recombinant P. falciparum hemolysin III-induced hemolysis was partially inhibited by glibenclamide, a known channel antagonist. Studies with polyethylene glycol molecules of different molecular weights indicated a pore size of approximately 3.2 nm. Heterologous expression of recombinant P. falciparum hemolysin III in Xenopus oocytes demonstrated early hypotonic lysis similar to that of the pore-forming aquaporin control. Live fluorescence microscopy localized transfected recombinant green fluorescent protein (GFP)-tagged P. falciparum hemolysin III to the essential digestive vacuole of the P. falciparum parasite. These transfected trophozoites also possessed a swollen digestive vacuole phenotype. Native Plasmodium hemolysin III in the digestive vacuole may contribute to lysis of the parasitophorous vacuole membrane derived from the host erythrocyte. After merozoite egress from infected erythrocytes, remnant P. falciparum hemolysin III released from digestive vacuoles could potentially contribute to lysis of uninfected erythrocytes to contribute to severe life-threatening anemia. PMID:25148832

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

    PubMed

    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.

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

    PubMed

    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.

  11. Thrombocytopenia in Plasmodium falciparum, Plasmodium vivax and mixed infection malaria: a study from Bikaner (Northwestern India).

    PubMed

    Kochar, Dhanpat Kumar; Das, Ashis; Kochar, Abhishek; Middha, Sheetal; Acharya, Jyoti; Tanwar, Gajanand Singh; Gupta, Anjana; Pakalapati, Deepak; Garg, Shilpi; Saxena, Vishal; Subudhi, Amit Kumar; Boopathi, P A; Sirohi, Parmendra; Kochar, Sanjay Kumar

    2010-01-01

    The occurrence, relation and magnitude of thrombocytopenia in different species of malaria are not clearly defined. This study included 1,064 patients admitted with malaria to study thrombocytopenia (platelet count <150,000 /cumm) in Plasmodium falciparum (Pf) and Plasmodium vivax (Pv) mono infection and mixed infection (Pf + Pv). The species diagnosis was done by peripheral blood film (PBF) and rapid diagnostic test (RDT). Validation by polymerase chain reaction (PCR) was done only in patients with severe thrombocytopenia (platelet count <20,000 /cumm). The breakup of patients was 525 (49.34%) Pf, 460 (43.23%) Pv and 79 (7.42%) mixed malaria (Pf + Pv). Thrombocytopenia was observed in 24.6% (262/1064) patients. The risk was greatest in the mixed infections in comparison to monoinfection individually (43.04% [34/79]; mixed vs Pv monoinfection: Odds Ratio [OR] = 1.675 [95% Confidence Interval (CI) 1.029-2.726], p < 0.0366; mixed vs Pf monoinfection: OR=3.911 [95% CI 2.367-6.463], p < 0.0001). Pv monoinfection (31.09% [143/460]) had greater risk compared to Pf monoinfection (16.19% [85/525]; OR = 2.335 [95% CI 1.722-3.167], p < 0.0001). The occurrence of severe thrombocytopenia was also higher in Pv monoinfection (18.18% [26/143]) in comparison to either Pf monoinfection (10.59% [9/85], OR = 1.877 (95% CI 0.834-4.223)) or mixed infection (11.76% [4/34]; OR = 1.667 (95% CI 0.540-5.142) but this association was statistically not significant. Six patients (3 Pv, 2 Pf and 1 mixed) developed severe epistaxis requiring platelet transfusion. There was no relation between parasite density and platelet count as many patients with severe thrombocytopenia had parasite density similar to patients without thrombocytopenia. We found that the association of thrombocytopenia was statistically more significant with P. vivax monoinfection as compared to P. falciparum.

  12. In vitro response of Plasmodium falciparum to chloroquine and mefloquine in southeast Madagascar.

    PubMed

    Kightlinger, M B; Kightlinger, L K

    1988-01-01

    46 isolates of Plasmodium falciparum collected in the Tolagnaro (Fort Dauphin) area of Southeast Madagascar were assessed with WHO in vitro micro-technique test kits to determine their susceptibility to chloroquine and mefloquine. The results of the tests indicated low grade resistance to chloroquine and satisfactory response to mefloquine.

  13. A non-pharmaceutical form of Artemisia annua is not effective in preventing Plasmodium falciparum malaria.

    PubMed

    Lagarce, Laurence; Lerolle, Nicolas; Asfar, Pierre; Le Govic, Yohann; Lainé-Cessac, Pascale; de Gentile, Ludovic

    2016-05-01

    Non-pharmaceutical forms of Artemisia annua (a Chinese plant containing artemisinin) are used by some travellers who believe these products are safer than anti-malarial drugs. We report two cases of severe Plasmodium falciparum malaria requiring hospitalization in an Intensive Care Unit following prophylaxis with non-pharmaceutical A. annua in French travellers.

  14. Slow Clearance of Plasmodium falciparum in Severe Pediatric Malaria, Uganda, 2011–2013

    PubMed Central

    Hawkes, Michael; Conroy, Andrea L.; Opoka, Robert O.; Namasopo, Sophie; Zhong, Kathleen; Liles, W. Conrad; John, Chandy C.

    2015-01-01

    Plasmodium falciparum resistance to artemisinin derivatives is emerging in Asia. We examined molecular markers of resistance in 78 children in Uganda who had severe malaria and were treated with intravenous artesunate. We observed in the K13-propeller domain, A578S, a low-frequency (3/78), nonsynonymous, single-nucleotide polymorphism associated with prolonged parasite clearance. PMID:26079933

  15. In vitro activities of furoquinoline and acridone alkaloids against Plasmodium falciparum.

    PubMed Central

    Basco, L K; Mitaku, S; Skaltsounis, A L; Ravelomanantsoa, N; Tillequin, F; Koch, M; Le Bras, J

    1994-01-01

    The in vitro activities of furo[2,3b]quinoline and acridone alkaloids against Plasmodium falciparum were evaluated by an isotopic semimicrotest. A pyran ring in the furoquinoline nucleus and 2-O-pyranoglycoside and 2-nitro substituents in the acridone nucleus improved the antimalarial activities of the compounds. These findings provide a clue for further chemical modifications. PMID:8067758

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

    USDA-ARS?s Scientific Manuscript database

    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...

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

    PubMed Central

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

    2017-01-01

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

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

    USDA-ARS?s Scientific Manuscript database

    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...

  19. In vitro activity of the enantiomers of mefloquine, halofantrine and enpiroline against Plasmodium falciparum.

    PubMed

    Basco, L K; Gillotin, C; Gimenez, F; Farinotti, R; Le Bras, J

    1992-05-01

    The in vitro activity of the enantiomers of mefloquine, halofantrine and enpiroline was compared against chloroquine-resistant and -susceptible strains of Plasmodium falciparum using a semi-micro drug susceptibility test. For each strain, the corresponding enantiomers exhibited similar activities. The enantiomers of halofantrine were the most active against both susceptible and resistant strains, followed by the enantiomers of mefloquine and enpiroline.

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

    PubMed Central

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

    1991-01-01

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

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

    PubMed Central

    Sander, Adam F.; Lavstsen, Thomas; Rask, Thomas S.; Lisby, Michael; Salanti, Ali; Fordyce, Sarah L.; Jespersen, Jakob S.; Carter, Richard; Deitsch, Kirk W.; Theander, Thor G.; Pedersen, Anders Gorm; Arnot, David E.

    2014-01-01

    Many bacterial, viral and parasitic pathogens undergo antigenic variation to counter host immune defense mechanisms. In Plasmodium falciparum, the most lethal of human malaria parasites, switching of var gene expression results in alternating expression of the adhesion proteins of the Plasmodium falciparum-erythrocyte membrane protein 1 class on the infected erythrocyte surface. Recombination clearly generates var diversity, but the nature and control of the genetic exchanges involved remain unclear. By experimental and bioinformatic identification of recombination events and genome-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. PMID:24253306

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

    PubMed

    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.

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

    SciTech Connect

    Hazelton, Keith Z.; Ho, Meng-Chaio; Cassera, Maria B.; Clinch, Keith; Crump, Douglas R.; Rosario Jr., Irving; Merino, Emilio F.; Almo, Steve C.; Tyler, Peter C.; Schramm, Vern L.

    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.

  4. Functional Antibodies against VAR2CSA in Nonpregnant Populations from Colombia Exposed to Plasmodium falciparum and Plasmodium vivax

    PubMed Central

    Doritchamou, Justin; Arango, Eliana M.; Cabrera, Ana; Arroyo, Maria Isabel; Kain, Kevin C.; Ndam, Nicaise Tuikue; Maestre, Amanda

    2014-01-01

    In pregnancy, parity-dependent immunity is observed in response to placental infection with Plasmodium falciparum. Antibodies recognize the surface antigen, VAR2CSA, expressed on infected red blood cells and inhibit cytoadherence to the placental tissue. In most settings of malaria endemicity, antibodies against VAR2CSA are predominantly observed in multigravid women and infrequently in men, children, and nulligravid women. However, in Colombia, we detected antibodies against multiple constructs of VAR2CSA among men and children with acute P. falciparum and Plasmodium vivax infection. The majority of men and children (>60%) had high levels of IgGs against three recombinant domains of VAR2CSA: DBL5ε, DBL3X, and ID1-ID2. Surprisingly, these antibodies were observed only in pregnant women, men, and children exposed either to P. falciparum or to P. vivax. Moreover, the anti-VAR2CSA antibodies are of high avidity and efficiently inhibit adherence of infected red blood cells to chondroitin sulfate A in vitro, suggesting that they are specific and functional. These unexpected results suggest that there may be genotypic or phenotypic differences in the parasites of this region or in the host response to either P. falciparum or P. vivax infection outside pregnancy. These findings may hold significant clinical relevance to the pathophysiology and outcome of malaria infections in this region. PMID:24686068

  5. Protection against Plasmodium falciparum malaria by PfSPZ Vaccine

    PubMed Central

    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

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

    PubMed

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

    2015-11-01

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

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

    PubMed

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

    2015-03-18

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

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

    PubMed

    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.

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

    PubMed

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

    2008-09-15

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

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

    PubMed

    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.

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

    PubMed

    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.

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

    PubMed

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

    2016-03-15

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

  13. Pooled Amplicon Deep Sequencing of Candidate Plasmodium falciparum Transmission-Blocking Vaccine Antigens

    PubMed Central

    Juliano, Jonathan J.; Parobek, Christian M.; Brazeau, Nicholas F.; Ngasala, Billy; Randrianarivelojosia, Milijaona; Lon, Chanthap; Mwandagalirwa, Kashamuka; Tshefu, Antoinette; Dhar, Ravi; Das, Bidyut K.; Hoffman, Irving; Martinson, Francis; Mårtensson, Andreas; Saunders, David L.; Kumar, Nirbhay; Meshnick, Steven R.

    2016-01-01

    Polymorphisms within Plasmodium falciparum vaccine candidate antigens have the potential to compromise vaccine efficacy. Understanding the allele frequencies of polymorphisms in critical binding regions of antigens can help in the designing of strain-transcendent vaccines. Here, we adopt a pooled deep-sequencing approach, originally designed to study P. falciparum drug resistance mutations, to study the diversity of two leading transmission-blocking vaccine candidates, Pfs25 and Pfs48/45. We sequenced 329 P. falciparum field isolates from six different geographic regions. Pfs25 showed little diversity, with only one known polymorphism identified in the region associated with binding of transmission-blocking antibodies among our isolates. However, we identified four new mutations among eight non-synonymous mutations within the presumed antibody-binding region of Pfs48/45. Pooled deep sequencing provides a scalable and cost-effective approach for the targeted study of allele frequencies of P. falciparum candidate vaccine antigens. PMID:26503281

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

    PubMed Central

    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

    2011-01-01

    SUMMARY 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 lifecycle 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 novel 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. PMID:21700207

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

    PubMed

    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. Plasmodium falciparum mdr1 mutations and in vivo chloroquine resistance in Indonesia.

    PubMed

    Gómez-Saladín, E; Fryauff, D J; Taylor, W R; Laksana, B S; Susanti, A I; Purnomo; Subianto, B; Richie, T L

    1999-08-01

    Mutations in the Pfmdr1 gene are reported to be associated with chloroquine resistance in some Plasmodium falciparum isolates. A polymerase chain reaction/restriction fragment length polymorphism method was used for the detection of Pfmdr1 mutations in chloroquine-resistant field isolates of P. falciparum collected in Irian Jaya. The frequency of Pfmdr1 mutations was significantly higher in chloroquine-resistant P. falciparum parasites than background frequencies observed in the same location. The 7G8 mutation was identified in some parasites although always in a mixed genotype status. Chloroquine-resistant P. falciparum specimens were characterized using the World Health Organization 28-day criteria, supplemented by demonstrating adequate chloroquine absorption and genetic analysis.

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

    PubMed Central

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

    2016-01-01

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

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

    SciTech Connect

    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.

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

    PubMed

    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.

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

    PubMed Central

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

    2015-01-01

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

  1. Dihydroartemisinin-piperaquine for treating uncomplicated Plasmodium falciparum malaria

    PubMed Central

    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

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

    DTIC Science & Technology

    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. Immune activation during cerebellar dysfunction following Plasmodium falciparum malaria.

    PubMed

    de Silva, H J; Hoang, P; Dalton, H; de Silva, N R; Jewell, D P; Peiris, J B

    1992-01-01

    Evidence for immune activation was investigated in 12 patients with a rare syndrome of self-limiting, delayed onset cerebellar dysfunction following an attack of falciparum malaria which occurred 18-26 d previously. Concentrations of tumour necrosis factor, interleukin 6 and interleukin 2 were all significantly higher in serum samples of patients during cerebellar ataxia than in recovery sera and in the sera of 8 patients who did not develop delayed cerebellar dysfunction following an attack of falciparum malaria. Cytokine concentrations in the cerebrospinal fluid were also significantly higher in ataxic patients than in controls. These findings suggest that immunological mechanisms may play a role in delayed cerebellar dysfunction following falciparum malaria.

  4. The Plasmodium falciparum exportome contains non-canonical PEXEL/HT proteins.

    PubMed

    Schulze, Jana; Kwiatkowski, Marcel; Borner, Janus; Schlüter, Hartmut; Bruchhaus, Iris; Burmester, Thorsten; Spielmann, Tobias; Pick, Christian

    2015-07-01

    The pathogenicity of Plasmodium falciparum is partly due to parasite-induced host cell modifications. These modifications are facilitated by exported P. falciparum proteins, collectively referred to as the exportome. Export of several hundred proteins is mediated by the PEXEL/HT, a protease cleavage site. The PEXEL/HT is usually comprised of five amino acids, of which R at position 1, L at position 3 and E, D or Q at position 5 are conserved and important for export. Non-canonical PEXEL/HTs with K or H at position 1 and/or I at position 3 are presently considered non-functional. Here, we show that non-canonical PEXEL/HT proteins are overrepresented in P. falciparum and other Plasmodium species. Furthermore, we show that non-canonical PEXEL/HTs can be cleaved and can promote export in both a REX3 and a GBP reporter, but not in a KAHRP reporter, indicating that non-canonical PEXEL/HTs are functional in concert with a supportive sequence environment. We then selected P. falciparum proteins with a non-canonical PEXEL/HT and show that some of these proteins are exported and that their export depends on non-canonical PEXEL/HTs. We conclude that PEXEL/HT plasticity is higher than appreciated and that non-canonical PEXEL/HT proteins cannot categorically be excluded from Plasmodium exportome predictions.

  5. Submicroscopic and asymptomatic Plasmodium falciparum and Plasmodium vivax infections are common in western Thailand - molecular and serological evidence.

    PubMed

    Baum, Elisabeth; Sattabongkot, Jetsumon; Sirichaisinthop, Jeeraphat; Kiattibutr, Kirakorn; Davies, D Huw; Jain, Aarti; Lo, Eugenia; Lee, Ming-Chieh; Randall, Arlo Z; Molina, Douglas M; Liang, Xiaowu; Cui, Liwang; Felgner, Philip L; Yan, Guiyun

    2015-02-25

    Malaria is a public health problem in parts of Thailand, where Plasmodium falciparum and Plasmodium vivax are the main causes of infection. In the northwestern border province of Tak parasite prevalence is now estimated to be less than 1% by microscopy. Nonetheless, microscopy is insensitive at low-level parasitaemia. The objective of this study was to assess the current epidemiology of falciparum and vivax malaria in Tak using molecular methods to detect exposure to and infection with parasites; in particular, the prevalence of asymptomatic infections and infections with submicroscopic parasite levels. Three-hundred microlitres of whole blood from finger-prick were collected into capillary tubes from residents of a sentinel village and from patients at a malaria clinic. Pelleted cellular fractions were screened by quantitative PCR to determine parasite prevalence, while plasma was probed on a protein microarray displaying hundreds of P. falciparum and P. vivax proteins to obtain antibody response profiles in those individuals. Of 219 samples from the village, qPCR detected 25 (11.4%) Plasmodium sp. infections, of which 92% were asymptomatic and 100% were submicroscopic. Of 61 samples from the clinic patients, 27 (44.3%) were positive by qPCR, of which 25.9% had submicroscopic parasite levels. Cryptic mixed infections, misdiagnosed as single-species infections by microscopy, were found in 7 (25.9%) malaria patients. All sample donors, parasitaemic and non-parasitaemic alike, had serological evidence of parasite exposure, with 100% seropositivity to at least 54 antigens. Antigens significantly associated with asymptomatic infections were P. falciparum MSP2, DnaJ protein, putative E1E2 ATPase, and three others. These findings suggest that parasite prevalence is higher than currently estimated by local authorities based on the standard light microscopy. As transmission levels drop in Thailand, it may be necessary to employ higher throughput and sensitivity methods for

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

    PubMed Central

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

    2009-01-01

    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. PMID:19279206

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

    PubMed

    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.

  8. The Limits and Intensity of Plasmodium falciparum Transmission: Implications for Malaria Control and Elimination Worldwide

    PubMed Central

    Guerra, Carlos A; Gikandi, Priscilla W; Tatem, Andrew J; Noor, Abdisalan M; Smith, Dave L; Hay, Simon I; Snow, Robert W

    2008-01-01

    Background The efficient allocation of financial resources for malaria control using appropriate combinations of interventions requires accurate information on the geographic distribution of malaria risk. An evidence-based description of the global range of Plasmodium falciparum malaria and its endemicity has not been assembled in almost 40 y. This paper aims to define the global geographic distribution of P. falciparum malaria in 2007 and to provide a preliminary description of its transmission intensity within this range. Methods and Findings The global spatial distribution of P. falciparum malaria was generated using nationally reported case-incidence data, medical intelligence, and biological rules of transmission exclusion, using temperature and aridity limits informed by the bionomics of dominant Anopheles vector species. A total of 4,278 spatially unique cross-sectional survey estimates of P. falciparum parasite rates were assembled. Extractions from a population surface showed that 2.37 billion people lived in areas at any risk of P. falciparum transmission in 2007. Globally, almost 1 billion people lived under unstable, or extremely low, malaria risk. Almost all P. falciparum parasite rates above 50% were reported in Africa in a latitude band consistent with the distribution of Anopheles gambiae s.s. Conditions of low parasite prevalence were also common in Africa, however. Outside of Africa, P. falciparum malaria prevalence is largely hypoendemic (less than 10%), with the median below 5% in the areas surveyed. Conclusions This new map is a plausible representation of the current extent of P. falciparum risk and the most contemporary summary of the population at risk of P. falciparum malaria within these limits. For 1 billion people at risk of unstable malaria transmission, elimination is epidemiologically feasible, and large areas of Africa are more amenable to control than appreciated previously. The release of this information in the public domain will

  9. Potentiation of antimalarial drug action by chlorpheniramine against multidrug-resistant Plasmodium falciparum in vitro.

    PubMed

    Nakornchai, Sunan; Konthiang, Phattanapong

    2006-09-01

    Chlorpheniramine, a histamine H1 receptor antagonist, was assayed for in vitro antimalarial activity against multidrug-resistant Plasmodium falciparum K1 strain and chloroquine-resistant P. falciparum T9/94 clone, by measuring the 3H-hypoxanthine incorporation. Chlorphenirame inhibited P. falciparum K1 and T9/94 growth with IC50 values of 136.0+/-40.2 microM and 102.0+/-22.6 microM respectively. A combination of antimalarial drug and chlorpheniramine was tested against resistant P. falciparum in vitro. Isobologram analysis showed that chlorpheniramine exerts marked synergistic action on chloroquine against P. falciparum K1 and T9/94. Chlorpheniramine also potentiated antimalarial action of mefloquine, quinine or pyronaridine against both of the resistant strains of P. falciparum. However, chlorpheniramine antagonism with artesunate was obtained in both P. falciparum K1 and T9/94. The results in this study indicate that antihistaminic drugs may be promising candidates for potentiating antimalarial drug action against drug resistant malarial parasites.

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

    PubMed Central

    2011-01-01

    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) showed opposite

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

    PubMed

    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. Plasmodium falciparum and Plasmodium vivax infections in the owl monkey (Aotus trivirgatus). I. The courses of untreated infections.

    PubMed

    Schmidt, L H

    1978-07-01

    This study, the first of three designed to determine the feasibility of using owl monkeys infected with human plasmodia in the search for new, more broadly active antimalarial drugs, dealt with the characteristics of untreated infections with eight strains of Plasmodium falciparum and two strains of P. vivax. Such infections, induced by standardized inocula of these strains in 1,733 monkeys, all Aotus trivirgatus griseimembra, were followed from day of inoculation to death of self-cure. The virulence of the various strains differed strikingly. Incidences of fatal reactions, ranging from 24.4--89.4% and 8.1--45.8%, respectively, in infections with strains of P. falciparum and P. vivax, were closely related to the rate at which parasitemia evolved, the height of parasitemia in the primary attack, and/or the time period over which a high parasite level was sustained. Antemortem symptom complexes and gross tissue and organ reactions in infections with P. falciparum varied with survival time, but within that boundary, were the same for infections with all eight strains of this plasmodium. Morbidity in both fatal and self-limited infections with both plasmodial species was related to height of parasitemia; however, at comparable parasite levels, symptoms exhibited in infections with P. vivax were more severe than in infections with P. falciparum. Overall, the characteristics of infections with these plasmodia in owl monkeys were remarkably similar to those of human infections. With respect to biological features, infections with P. falciparum and P. vivax in this simian host appear to have much to offer in the search for new antimalarial drugs.

  13. New compounds hybrids 1h-1,2,3-triazole-quinoline against Plasmodium falciparum.

    PubMed

    Boechat, Núbia; Ferreira, Maria de Lourdes G; Pinheiro, Luiz C S; Jesus, Antônio M L; Leite, Milene M M; Júnior, Carlos C S; Aguiar, Anna C C; de Andrade, Isabel M; Krettli, Antoniana U

    2014-09-01

    Malaria is one of the most prevalent parasitic diseases in the world. The global importance of this disease, current vector control limitations, and the absence of an effective vaccine make the use of therapeutic antimalarial drugs the main strategy to control malaria. Chloroquine is a cost-effective antimalarial drug with a relatively robust safety profile, or therapeutic index. However, chloroquine is no longer used alone to treat patients with Plasmodium falciparum due to the emergence and spread of chloroquine-resistant strains, which have also been reported for Plasmodium vivax. However, the activity of 1,2,3-triazole derivatives against chloroquine-sensitive and chloroquine-resistant strains of P. falciparum has been reported in the literature. To enhance the anti-P. falciparum activity of quinoline derivatives, we synthesized 11 new quinoline-1H-1,2,3-triazole hybrids with different substituents in the 4-positions of the 1H-1,2,3-triazole ring, which were assayed against the W2-chloroquine-resistant P. falciparum clone. Six compounds exhibited activity against the P. falciparum W2 clone, chloroquine-resistant, with IC50 values ranging from 1.4 to 46 μm. None of these compounds was toxic to a normal monkey kidney cell line, thus exhibiting good selectivity indexes, as high 351 for one compound (11).

  14. Plasmodium falciparum proteins involved in cytoadherence of infected erythrocytes to chemokine CX3CL1

    PubMed Central

    Hermand, Patricia; Cicéron, Liliane; Pionneau, Cédric; Vaquero, Catherine; Combadière, Christophe; Deterre, Philippe

    2016-01-01

    Malaria caused by Plasmodium falciparum is associated with cytoadherence of infected red blood cells (iRBC) to endothelial cells. Numerous host molecules have been involved in cytoadherence, including the adhesive chemokine CX3CL1. Most of the identified parasite ligands are from the multigenic and hypervariable Plasmodium falciparum Erythrocyte Membrane Protein 1 (PfEMP1) family which makes them poor targets for the development of a broadly protective vaccine. Using proteomics, we have identified two 25-kDa parasite proteins with adhesive properties for CX3CL1, called CBP for CX3CL1 Binding Proteins. CBPs are coded by single-copy genes with little polymorphic variation and no homology with other P. falciparum gene products. Specific antibodies raised against epitopes from the predicted extracellular domains of each CBP efficiently stain the surface of RBC infected with trophozoites or schizonts, which is a strong indication of CBP expression at the surface of iRBC. These anti-CBP antibodies partially neutralize iRBC adherence to CX3CL1. This adherence is similarly inhibited in the presence of peptides from the CBP extracellular domains, while irrelevant peptides had no such effect. CBP1 and CBP2 are new P. falciparum ligands for the human chemokine CX3CL1. The identification of this non-polymorphic P. falciparum factors provides a new avenue for innovative vaccination approaches. PMID:27653778

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

    PubMed

    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.

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

    PubMed

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

    2007-06-01

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

  17. Identification and Mechanistic Evaluation of Hemozoin-Inhibiting Triarylimidazoles Active against Plasmodium falciparum.

    PubMed

    Wicht, Kathryn J; Combrinck, Jill M; Smith, Peter J; Hunter, Roger; Egan, Timothy J

    2017-02-09

    In a previous study, target based screening was carried out for inhibitors of β-hematin (synthetic hemozoin) formation, and a series of triarylimidazoles were identified as active against Plasmodium falciparum. Here, we report the subsequent synthesis and testing of derivatives with varying substituents on the three phenyl rings for this series. The results indicated that a 2-hydroxy-1,3-dimethoxy substitution pattern on ring A is required for submicromolar parasite activity. In addition, cell-fractionation studies revealed uncommonly large, dose-dependent increases of P. falciparum intracellular exchangeable (free) heme, correlating with decreased parasite survival for β-hematin inhibiting derivatives.

  18. Lactate retards the development of erythrocytic stages of the human malaria parasite Plasmodium falciparum.

    PubMed

    Hikosaka, Kenji; Hirai, Makoto; Komatsuya, Keisuke; Ono, Yasuo; Kita, Kiyoshi

    2015-06-01

    The intraerythrocytic form of the human malaria parasite Plasmodium falciparum relies on glycolysis for its energy requirements. In glycolysis, lactate is an end product. It is therefore known that lactate accumulates in in vitro culture; however, its influence on parasite growth remains unknown. Here we investigated the effect of lactate on the development of P. falciparum during in vitro culture under lactate supplementation in detail. Results revealed that lactate retarded parasite development and reduced the number of merozoites in the schizont stage. These findings suggest that lactate has the potential to affect parasite development.

  19. Steroid Pulse Therapy May Mitigate Prolonged Neurological Manifestations after Eradication of Severe Plasmodium falciparum Parasitemia

    PubMed Central

    Hasegawa, Chihiro; Inagaki, Akiko; Yamada, Gohei; Morita, Koji; Kitamura, Isamu; Ariyoshi, Koya

    2016-01-01

    A 58-year-old Japanese man with a high parasitemia of Plasmodium falciparum, returning from Uganda, was admitted to our hospital since his consciousness level rapidly deteriorated after the initial dose of mefloquine. Despite the parasitemia was cleared by quinine by day 7, the coma remained unchanged and diffuse leukoencephalopathy was detected on magnetic resonance image. Steroid pulse therapy was initiated on day 8. Subsequently, the neurological manifestations improved and he was discharged on day 73 without any sequelae. Pathogenesis of P. falciparum causing cerebral malaria is diverse and complex. If neurological symptoms unusually prolong, steroid may be an effective treatment option. PMID:27853090

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

    PubMed

    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.

  1. Two Cases of Plasmodium falciparum Malaria in the Netherlands without Recent Travel to a Malaria-Endemic Country

    PubMed Central

    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.

    2013-01-01

    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. PMID:23857021

  2. Sex-partitioning of the Plasmodium falciparum Stage V Gametocyte Proteome Provides Insight into falciparum-specific Cell Biology*

    PubMed Central

    Tao, Dingyin; Ubaida-Mohien, Ceereena; Mathias, Derrick K.; King, Jonas G.; Pastrana-Mena, Rebecca; Tripathi, Abhai; Goldowitz, Ilana; Graham, David R.; Moss, Eli; Marti, Matthias; Dinglasan, Rhoel R.

    2014-01-01

    One of the critical gaps in malaria transmission biology and surveillance is our lack of knowledge about Plasmodium falciparum gametocyte biology, especially sexual dimorphic development and how sex ratios that may influence transmission from the human to the mosquito. Dissecting this process has been hampered by the lack of sex-specific protein markers for the circulating, mature stage V gametocytes. The current evidence suggests a high degree of conservation in gametocyte gene complement across Plasmodium, and therefore presumably for sex-specific genes as well. To better our understanding of gametocyte development and subsequent infectiousness to mosquitoes, we undertook a Systematic Subtractive Bioinformatic analysis (filtering) approach to identify sex-specific P. falciparum NF54 protein markers based on a comparison with the Dd2 strain, which is defective in producing males, and with syntenic male and female proteins from the reanalyzed and updated P. berghei (related rodent malaria parasite) gametocyte proteomes. This produced a short list of 174 male- and 258 female-enriched P. falciparum stage V proteins, some of which appear to be under strong diversifying selection, suggesting ongoing adaptation to mosquito vector species. We generated antibodies against three putative female-specific gametocyte stage V proteins in P. falciparum and confirmed either conserved sex-specificity or the lack of cross-species sex-partitioning. Finally, our study provides not only an additional resource for mass spectrometry-derived evidence for gametocyte proteins but also lays down the foundation for rational screening and development of novel sex-partitioned protein biomarkers and transmission-blocking vaccine candidates. PMID:25056935

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

    PubMed Central

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

    2014-01-01

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

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

    PubMed

    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.

  5. Functional Analysis of Plasmodium vivax Dihydrofolate Reductase-Thymidylate Synthase Genes through Stable Transformation of Plasmodium falciparum

    PubMed Central

    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. PMID:22792308

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

    PubMed

    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.

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

    PubMed Central

    2012-01-01

    Background Copper is an essential catalytic co-factor for metabolically important cellular enzymes, such as cytochrome-c oxidase. Eukaryotic cells acquire copper through a copper transport protein and distribute intracellular copper using molecular chaperones. The copper chelator, neocuproine, inhibits Plasmodium falciparum ring-to-trophozoite transition in vitro, indicating a copper requirement for malaria parasite development. How the malaria parasite acquires or secretes copper still remains to be fully elucidated. Methods PlasmoDB was searched for sequences corresponding to candidate P. falciparum copper-requiring proteins. The amino terminal domain of a putative P. falciparum copper transport protein was cloned and expressed as a maltose binding fusion protein. The copper binding ability of this protein was examined. Copper transport protein-specific anti-peptide antibodies were generated in chickens and used to establish native protein localization in P. falciparum parasites by immunofluorescence microscopy. Results Six P. falciparum copper-requiring protein orthologs and a candidate P. falciparum copper transport protein (PF14_0369), containing characteristic copper transport protein features, were identified in PlasmoDB. The recombinant amino terminal domain of the transport protein bound reduced copper in vitro and within Escherichia coli cells during recombinant expression. Immunolocalization studies tracked the copper binding protein translocating from the erythrocyte plasma membrane in early ring stage to a parasite membrane as the parasites developed to schizonts. The protein appears to be a PEXEL-negative membrane protein. Conclusion Plasmodium falciparum parasites express a native protein with copper transporter characteristics that binds copper in vitro. Localization of the protein to the erythrocyte and parasite plasma membranes could provide a mechanism for the delivery of novel anti-malarial compounds. PMID:23190769

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

    PubMed

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

    2017-04-01

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

  9. Molecular cloning and characterisation of the RESA gene, a marker of genetic diversity of Plasmodium falciparum.

    PubMed

    Moyano, Eva M; González, Luis Miguel; Cuevas, Laureano; Perez-Pastrana, Esperanza; Santa-Maria, Ysmael; Benito, Agustín

    2010-07-01

    To identity immunodiagnostic antigen genes, a Plasmodium falciparum (Dd2 clone) expression library was screened using human immune sera. The ring-infected erythrocyte surface antigen (RESA) was isolated: this antigen of the resistant clone presents repeat tandem sequences like the 3D7 clone, albeit in different numbers. RESA has been studied as a marker of genetic diversity, with different sizes being observed in different isolates and clones of Plasmodium falciparum. The native protein was localised in cultures by western-blot and immuno-transmission electron microscopy. The antigenicity of RESA was evaluated by ELISA, using the carboxy-terminal repeat region as antigen. The assay's sensitivity and specificity were 78.2 and 94% respectively.

  10. Evaluation of a rapid and inexpensive dipstick assay for the diagnosis of Plasmodium falciparum malaria.

    PubMed Central

    Mills, C. D.; Burgess, D. C.; Taylor, H. J.; Kain, K. C.

    1999-01-01

    Rapid, accurate and affordable methods are needed for the diagnosis of malaria. Reported here is an evaluation of a new immunochromatographic strip, the PATH Falciparum Malaria IC Strip, which is impregnated with an immobilized IgM monoclonal antibody that binds to the HRP-II antigen of Plasmodium falciparum. In contrast to other commercially available kits marketed for the rapid diagnosis of falciparum malaria, this kit should be affordable in the malaria-endemic world. Using microscopy and polymerase chain reaction (PCR)-based methods as reference standards, we compared two versions of the PATH test for the detection of P. falciparum infection in 200 febrile travellers. As determined by PCR and microscopy, 148 travellers had malaria, 50 of whom (33.8%) were infected with P. falciparum. Compared with PCR, the two versions of the PATH test had initial sensitivities of 90% and 88% and specificities of 97% and 96%, respectively, for the detection of falciparum malaria. When discrepant samples were retested blindly with a modified procedure (increased sample volume and longer washing step) the sensitivity and specificity of both kits improved to 96% and 99%, respectively. The two remaining false negatives occurred in samples with < 100 parasites per microliter of blood. The accuracy, simplicity and predicted low cost may make this test a useful diagnostic tool in malaria-endemic areas. PMID:10444878

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

    PubMed Central

    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

  12. The Spiroindolone KAE609 Does Not Induce Dormant Ring Stages in Plasmodium falciparum Parasites

    PubMed Central

    Van Breda, Karin; Rowcliffe, Kerryn; Diagana, Thierry T.; Edstein, Michael D.

    2016-01-01

    In vitro drug treatment with artemisinin derivatives, such as dihydroartemisinin (DHA), results in a temporary growth arrest (i.e., dormancy) at an early ring stage in Plasmodium falciparum. This response has been proposed to play a role in the recrudescence of P. falciparum infections following monotherapy with artesunate and may contribute to the development of artemisinin resistance in P. falciparum malaria. We demonstrate here that artemether does induce dormant rings, a finding which further supports the class effect of artemisinin derivatives in inducing the temporary growth arrest of P. falciparum parasites. In contrast and similarly to lumefantrine, the novel and fast-acting spiroindolone compound KAE609 does not induce growth arrest at the early ring stage of P. falciparum and prevents the recrudescence of DHA-arrested rings at a low concentration (50 nM). Our findings, together with previous clinical data showing that KAE609 is active against artemisinin-resistant K13 mutant parasites, suggest that KAE609 could be an effective partner drug with a broad range of antimalarials, including artemisinin derivatives, in the treatment of multidrug-resistant P. falciparum malaria. PMID:27297484

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

    DTIC Science & Technology

    2006-01-01

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

  14. Protection of Humans against Malaria by Immunization with Radiation-Attenuated Plasmodium falciparum Sporozoites

    DTIC Science & Technology

    2002-04-15

    departments of the Navy or Army. a Present affiliations: Celera Genomics , Rockville, Maryland (S.L.H.); Pe- diatric Specialty Center, Monroe, Louisiana...Stephen L. Hoffman, Biologics, Celera Genomics , 45 W. Gude Dr., Rockville, MD 20850 (stephen.hoffman@celera.com). Received 1 August 2001; revised 19...Protection of Humans against Malaria by Immunization with Radiation-Attenuated Plasmodium falciparum Sporozoites Stephen L. Hoffman,1,a Lucy M. L

  15. Complement and Antibody-Mediated Enhancement of Erythrocyte Invasion by Plasmodium Falciparum

    DTIC Science & Technology

    2015-09-01

    ABSTRACT Plasmodium falciparum malaria kills hundreds of thousands of people every year. A vaccine that blocks red blood cell (RBC) invasion has been an...TERMS Malaria , complement, red blood cells, antibodies, merozoite, invasion 16. SECURITY CLASSIFICATION OF: 17. LIMITATION OF ABSTRACT 18. NUMBER OF...responsible for most of the nearly 1 million deaths from malaria each year. The invasion of red blood cells (RBCs) by the parasite (merozoites) is an

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

    PubMed

    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.

  17. The Distribution of Circumsporozoite Protein (CS) in Anopheles Stephensi Mosquitoes Infected with Plasmodium Falciparum Malaria

    DTIC Science & Technology

    1990-01-01

    389 in differentiating oocysts, on remnant membranes left on the midgut Roitt IM, BrostoffJ, Male DK (1985): Immunology. St Louis, CV Mosby wall after...Plasmodium falciparum; Anopheles stephensi; Cir- on the mosquito midgut. As oocysts differentiated to ma- cumsporozoite protein; Fuchsin/naphthol AS-BI...and sporogony in the mosquito. During a blood meal, microscopy and an indirect fluorescent antibody test (IFAT). These the mosquito ingests the male

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

    NASA Astrophysics Data System (ADS)

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

    2010-05-01

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

  19. In vitro activity of the enantiomers of mefloquine, halofantrine and enpiroline against Plasmodium falciparum.

    PubMed Central

    Basco, L K; Gillotin, C; Gimenez, F; Farinotti, R; Le Bras, J

    1992-01-01

    The in vitro activity of the enantiomers of mefloquine, halofantrine and enpiroline was compared against chloroquine-resistant and -susceptible strains of Plasmodium falciparum using a semi-micro drug susceptibility test. For each strain, the corresponding enantiomers exhibited similar activities. The enantiomers of halofantrine were the most active against both susceptible and resistant strains, followed by the enantiomers of mefloquine and enpiroline. PMID:1524966

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

    PubMed

    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.

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

    PubMed

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

    1999-02-01

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

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

    PubMed

    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.

  3. Chloroquine and sulphadoxine-pyrimethamine sensitivity of Plasmodium falciparum parasites in a Brazilian endemic area

    PubMed Central

    Gama, Bianca Ervatti; de Oliveira, Natália K Almeida; Zalis, Mariano G; de Souza, José Maria; Santos, Fátima; Daniel-Ribeiro, Cláudio Tadeu; Ferreira-da-Cruz, Maria de Fátima

    2009-01-01

    Background The goal of the present study was the characterization of Plasmodium falciparum genes associated to malaria drug resistance (pfcrt, pfdhfr and pfdhps), in samples from two Brazilian localities. Methods Parasites from 65 P. falciparum samples were genotyped using nested-PCR and direct DNA sequencing. Results Six resistant sulphadoxine-pyrimethamine (SP) pfdhfr genotypes and one haplotype associated to SP sensitivity were detected. For pfcrt gene, SVMNT chloroquine (CQ)-resistant genotype was detected as well as the CVMNK CQ-sensitive haplotype in the same sample from Paragominas, that showed a SP-sensitive genotype. Conclusion This study is the first to document the sensitivity of P. falciparum parasites to CQ and SP in Brazilian field samples. The importance of these findings is discussed. PMID:19602248

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

    PubMed Central

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

    2014-01-01

    Iron deficiency and malaria have similar global distributions, and frequently co-exist in pregnant women and young children. Where both conditions are prevalent, iron supplementation is complicated by observations that iron deficiency anaemia protects against falciparum malaria, and that iron supplements increase susceptibility to clinically significant malaria, but the mechanisms remain obscure. Here, using an in vitro parasite culture system with erythrocytes from iron-deficient and replete human donors, we demonstrate that Plasmodium falciparum infects iron-deficient erythrocytes less efficiently. In addition, owing to merozoite preference for young erythrocytes, iron supplementation of iron-deficient individuals reverses the protective effects of iron deficiency. Our results provide experimental validation of field observations reporting protective effects of iron deficiency and harmful effects of iron administration on human malaria susceptibility. Because recovery from anaemia requires transient reticulocytosis, our findings imply that in malarious regions iron supplementation should be accompanied by effective measures to prevent falciparum malaria. PMID:25059846

  5. A forward genetic screen identifies erythrocyte CD55 as essential for Plasmodium falciparum invasion **

    PubMed Central

    Egan, Elizabeth S.; Jiang, Rays H.Y.; Moechtar, Mischka A.; Barteneva, Natasha S.; Weekes, Michael P.; Nobre, Luis V.; Gygi, Steven P.; Paulo, Joao A.; Frantzreb, Charles; Tani, Yoshihiko; Takahashi, Junko; Watanabe, Seishi; Goldberg, Jonathan; Paul, Aditya S.; Brugnara, Carlo; Root, David E.; Wiegand, Roger C.; Doench, John G.; Duraisingh, Manoj T.

    2015-01-01

    Efforts to identify host determinants for malaria have been hindered by the absence of a nucleus in erythrocytes, precluding genetic manipulation in the cell where the parasite replicates. We used cultured red blood cells derived from hematopoietic stem cells to carry out a forward genetic screen for Plasmodium falciparum host determinants. We found that CD55 is an essential host factor for P. falciparum invasion. CD55-null erythrocytes were refractory to invasion by all isolates of P. falciparum because parasites failed to attach properly to the erythrocyte surface. Thus, CD55 is an attractive target for the development of malaria therapeutics. Hematopoietic stem cell-based forward genetic screens may be valuable for the identification of additional host determinants of malaria pathogenesis. PMID:25954012

  6. Limonene Arrests Parasite Development and Inhibits Isoprenylation of Proteins in Plasmodium falciparum

    PubMed Central

    Moura, Ivan Cruz; Wunderlich, Gerhard; Uhrig, Maria L.; Couto, Alicia S.; Peres, Valnice J.; Katzin, Alejandro M.; Kimura, Emília A.

    2001-01-01

    Isoprenylation is an essential protein modification in eukaryotic cells. Herein, we report that in Plasmodium falciparum, a number of proteins were labeled upon incubation of intraerythrocytic forms with either [3H]farnesyl pyrophosphate or [3H]geranylgeranyl pyrophosphate. By thin-layer chromatography, we showed that attached isoprenoids are partially modified to dolichol and other, uncharacterized, residues, confirming active isoprenoid metabolism in this parasite. Incubation of blood-stage P. falciparum treated with the isoprenylation inhibitor limonene significantly decreased the parasites' progression from the ring stage to the trophozoite stage and at 1.22 mM, 50% of the parasites died after the first cycle. Using Ras- and Rap-specific monoclonal antibodies, putative Rap and Ras proteins of P. falciparum were immunoprecipitated. Upon treatment with 0.5 mM limonene, isoprenylation of these proteins was significantly decreased, possibly explaining the observed arrest of parasite development. PMID:11502528

  7. In Vitro Inhibition of Plasmodium falciparum Rosette Formation by Curdlan Sulfate▿

    PubMed Central

    Kyriacou, Helen M.; Steen, Katie E.; Raza, Ahmed; Arman, Monica; Warimwe, George; Bull, Peter C.; Havlik, Ivan; Rowe, J. Alexandra

    2007-01-01

    Spontaneous binding of infected erythrocytes to uninfected erythrocytes to form rosettes is a property of some strains of Plasmodium falciparum that is linked to severe complications of malaria. Curdlan sulfate (CRDS) is a sulfated glycoconjugate compound that is chemically similar to known rosette-inhibiting drugs such as heparin. CRDS has previously been shown to have antimalarial activity in vitro and is safe for clinical use. Here we show that CRDS at therapeutic levels (10 to 100 μg/ml) significantly reduces rosette formation in vitro in seven P. falciparum laboratory strains and in a group of 18 African clinical isolates. The strong ability to inhibit rosetting suggests that CRDS has the potential to reduce the severe complications and mortality rates from P. falciparum malaria among African children. Our data support further clinical trials of CRDS. PMID:17283200

  8. Estimating the parasitaemia of Plasmodium falciparum: experience from a national EQA scheme

    PubMed Central

    2013-01-01

    Background To examine performance of the identification and estimation of percentage parasitaemia of Plasmodium falciparum in stained blood films distributed in the UK National External Quality Assessment Scheme (UKNEQAS) Blood Parasitology Scheme. Methods Analysis of performance for the diagnosis and estimation of the percentage parasitaemia of P. falciparum in Giemsa-stained thin blood films was made over a 15-year period to look for trends in performance. Results An average of 25% of participants failed to estimate the percentage parasitaemia, 17% overestimated and 8% underestimated, whilst 5% misidentified the malaria species present. Conclusions Although the results achieved by participants for other blood parasites have shown an overall improvement, the level of performance for estimation of the parasitaemia of P. falciparum remains unchanged over 15 years. Possible reasons include incorrect calculation, not examining the correct part of the film and not examining an adequate number of microscope fields. PMID:24261625

  9. Mutation in pfmdr1 gene in chloroquine-resistant Plasmodium falciparum isolates, Southeast Iran.

    PubMed

    Jalousian, Fatemeh; Dalimi, Abdolhossein; Samiee, Siamak Mirab; Ghaffarifar, Fatemeh; Soleymanloo, Faramarz; Naghizadeh, Ramin

    2008-11-01

    The main objective of the present study was to detect point mutations at positions 86, 184, 1034, 1042, and 1246 of the Plasmodium falciparum multidrug resistance gene (pfmdr1) in blood samples collected from malaria patients in Chabahar, a harbor city located in Southeast Iran. Twenty-six blood samples from patients infected with P. falciparum, who had a chloroquine (CQ) response failure, were collected pre-treatment. Following treatment with CQ, drug susceptibility was assessed using an in vivo test. Molecular detection of single nucleotide polymorphisms (SNPs) was carried out using the LightCycler hybridization probe assay. The pfmdr1 N86Y mutation was found in six isolates (23.1%). Mutations at the four other positions were not observed in any isolates. The present study showed no mutation at codon positions 184, 1034, 1042, and 1246 of pfmdr1 in any of the Iranian P. falciparum isolates; thus these alleles cannot serve as markers for CQ resistance in Iran.

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

    NASA Technical Reports Server (NTRS)

    Li, Tao; Glushakova, Svetlana; Zimmerberg, Joshua

    2003-01-01

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

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

    NASA Astrophysics Data System (ADS)

    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.

  12. Uric Acid Is a Mediator of the Plasmodium falciparum-Induced Inflammatory Response

    PubMed Central

    Orengo, Jamie Marie; Leliwa-Sytek, Aleksandra; Evans, James E.; Evans, Barbara; van de Hoef, Diana; Nyako, Marian; Day, Karen; Rodriguez, Ana

    2009-01-01

    Background Malaria triggers a high inflammatory response in the host that mediates most of the associated pathologies and contributes to death. The identification of pro-inflammatory molecules derived from Plasmodium is essential to understand the mechanisms of pathogenesis and to develop targeted interventions. Uric acid derived from hypoxanthine accumulated in infected erythrocytes has been recently proposed as a mediator of inflammation in rodent malaria. Methods and Findings We found that human erythrocytes infected with Plasmodium falciparum gradually accumulate hypoxanthine in their late stages of development. To analyze the role of hypoxanthine-derived uric acid induced by P. falciparum on the inflammatory cytokine response from human blood mononuclear cells, cultures were treated with allopurinol, to inhibit uric acid formation from hypoxanthine, or with uricase, to degrade uric acid. Both treatments significantly reduce the secretion of TNF, IL-6, IL-1β and IL-10 from human cells. Conclusions and Significance Uric acid is a major contributor of the inflammatory response triggered by P. falciparum in human peripheral blood mononuclear cells. Since the inflammatory reaction induced by P. falciparum is considered a major cause of malaria pathogenesis, identifying the mechanisms used by the parasite to induce the host inflammatory response is essential to develop urgently needed therapies against this disease. PMID:19381275

  13. Ca2+ monitoring in Plasmodium falciparum using the yellow cameleon-Nano biosensor

    PubMed Central

    Pandey, Kishor; Ferreira, Pedro E.; Ishikawa, Takeshi; Nagai, Takeharu; Kaneko, Osamu; Yahata, Kazuhide

    2016-01-01

    Calcium (Ca2+)-mediated signaling is a conserved mechanism in eukaryotes, including the human malaria parasite, Plasmodium falciparum. Due to its small size (<10 μm) measurement of intracellular Ca2+ in Plasmodium is technically challenging, and thus Ca2+ regulation in this human pathogen is not well understood. Here we analyze Ca2+ homeostasis via a new approach using transgenic P. falciparum expressing the Ca2+ sensor yellow cameleon (YC)-Nano. We found that cytosolic Ca2+ concentration is maintained at low levels only during the intraerythrocytic trophozoite stage (30 nM), and is increased in the other blood stages (>300 nM). We determined that the mammalian SERCA inhibitor thapsigargin and antimalarial dihydroartemisinin did not perturb SERCA activity. The change of the cytosolic Ca2+ level in P. falciparum was additionally detectable by flow cytometry. Thus, we propose that the developed YC-Nano-based system is useful to study Ca2+ signaling in P. falciparum and is applicable for drug screening. PMID:27006284

  14. Population genetic analysis of Plasmodium falciparum parasites using a customized Illumina GoldenGate genotyping assay.

    PubMed

    Campino, Susana; Auburn, Sarah; Kivinen, Katja; Zongo, Issaka; Ouedraogo, Jean-Bosco; Mangano, Valentina; Djimde, Abdoulaye; Doumbo, Ogobara K; Kiara, Steven M; Nzila, Alexis; Borrmann, Steffen; Marsh, Kevin; Michon, Pascal; Mueller, Ivo; Siba, Peter; Jiang, Hongying; Su, Xin-Zhuan; Amaratunga, Chanaki; Socheat, Duong; Fairhurst, Rick M; Imwong, Mallika; Anderson, Timothy; Nosten, François; White, Nicholas J; Gwilliam, Rhian; Deloukas, Panos; MacInnis, Bronwyn; Newbold, Christopher I; Rockett, Kirk; Clark, Taane G; Kwiatkowski, Dominic P

    2011-01-01

    The diversity in the Plasmodium falciparum genome can be used to explore parasite population dynamics, with practical applications to malaria control. The ability to identify the geographic origin and trace the migratory patterns of parasites with clinically important phenotypes such as drug resistance is particularly relevant. With increasing single-nucleotide polymorphism (SNP) discovery from ongoing Plasmodium genome sequencing projects, a demand for high SNP and sample throughput genotyping platforms for large-scale population genetic studies is required. Low parasitaemias and multiple clone infections present a number of challenges to genotyping P. falciparum. We addressed some of these issues using a custom 384-SNP Illumina GoldenGate assay on P. falciparum DNA from laboratory clones (long-term cultured adapted parasite clones), short-term cultured parasite isolates and clinical (non-cultured isolates) samples from East and West Africa, Southeast Asia and Oceania. Eighty percent of the SNPs (n = 306) produced reliable genotype calls on samples containing as little as 2 ng of total genomic DNA and on whole genome amplified DNA. Analysis of artificial mixtures of laboratory clones demonstrated high genotype calling specificity and moderate sensitivity to call minor frequency alleles. Clear resolution of geographically distinct populations was demonstrated using Principal Components Analysis (PCA), and global patterns of population genetic diversity were consistent with previous reports. These results validate the utility of the platform in performing population genetic studies of P. falciparum.

  15. Comparative Genomics of Transcriptional Control in the Human Malaria Parasite Plasmodium falciparum

    PubMed Central

    Coulson, Richard M.R.; Hall, Neil; Ouzounis, Christos A.

    2004-01-01

    The life cycle of the parasite Plasmodium falciparum, responsible for the most deadly form of human malaria, requires specialized protein expression for survival in the mammalian host and insect vector. To identify components of processes controlling gene expression during its life cycle, the malarial genome—along with seven crown eukaryote group genomes—was queried with a reference set of transcription-associated proteins (TAPs). Following clustering on the basis of sequence similarity of the TAPs with their homologs, and together with hidden Markov model profile searches, 156 P. falciparum TAPs were identified. This represents about a third of the number of TAPs usually found in the genome of a free-living eukaryote. Furthermore, the P. falciparum genome appears to contain a low number of sequences, which are highly conserved and abundant within the kingdoms of free-living eukaryotes, that contribute to gene-specific transcriptional regulation. However, in comparison with these other eukaryotic genomes, the CCCH-type zinc finger (common in proteins modulating mRNA decay and translation rates) was found to be the most abundant in the P. falciparum genome. This observation, together with the paucity of malarial transcriptional regulators identified, suggests Plasmodium protein levels are primarily determined by posttranscriptional mechanisms. PMID:15256513

  16. Population dynamics of genetically diverse Plasmodium falciparum lineages: community-based prospective study in rural Amazonia

    PubMed Central

    ORJUELA-SÁNCHEZ, P.; SILVA-NUNES, M. DA; DA SILVA, N. S.; SCOPEL, K.K.G.; GONÇALVES, R. M.; MALAFRONTE, R. S.; FERREIRA, M. U.

    2010-01-01

    SUMMARY Temporal changes in the prevalence of antigenic variants in Plasmodium falciparum populations have been interpreted as evidence of immune-mediated frequency-dependent selection, but evolutively neutral processes may generate similar patterns of serotype replacement. Over 4 years, we investigated the population dynamics of P. falciparum polymorphisms at the community level by using 11 putatively neutral microsatellite markers. Plasmodium falciparum populations were less diverse than sympatric P. vivax isolates, with less multiple-clone infections, lower number of alleles per locus and lower virtual heterozygosity, but both species showed significant multilocus linkage disequilibrium. Evolutively neutral P. falciparum polymorphisms showed a high turnover rate, with few lineages persisting for several months in the population. Similar results had previously been obtained, in the same community, for sympatric P. vivax isolates. In contrast, the prevalence of the 2 dimorphic types of a major antigen, MSP-2, remained remarkably stable throughout the study period. We suggest that the relatively fast turnover of parasite lineages represents the typical population dynamics of neutral polymorphisms in small populations, with clear implications for the detection of frequency-dependent selection of polymorphisms. PMID:19631016

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

    PubMed

    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.

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

    PubMed Central

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

    2013-01-01

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

  19. Plasmodium falciparum CRK4 directs continuous rounds of DNA replication during schizogony.

    PubMed

    Ganter, Markus; Goldberg, Jonathan M; Dvorin, Jeffrey D; Paulo, Joao A; King, Jonas G; Tripathi, Abhai K; Paul, Aditya S; Yang, Jing; Coppens, Isabelle; Jiang, Rays H Y; Elsworth, Brendan; Baker, David A; Dinglasan, Rhoel R; Gygi, Steven P; Duraisingh, Manoj T

    2017-02-17

    Plasmodium parasites, the causative agents of malaria, have evolved a unique cell division cycle in the clinically relevant asexual blood stage of infection(1). DNA replication commences approximately halfway through the intracellular development following invasion and parasite growth. The schizont stage is associated with multiple rounds of DNA replication and nuclear division without cytokinesis, resulting in a multinucleated cell. Nuclei divide asynchronously through schizogony, with only the final round of DNA replication and segregation being synchronous and coordinated with daughter cell assembly(2,3). However, the control mechanisms for this divergent mode of replication are unknown. Here, we show that the Plasmodium-specific kinase PfCRK4 is a key cell-cycle regulator that orchestrates multiple rounds of DNA replication throughout schizogony in Plasmodium falciparum. PfCRK4 depletion led to a complete block in nuclear division and profoundly inhibited DNA replication. Quantitative phosphoproteomic profiling identified a set of PfCRK4-regulated phosphoproteins with greatest functional similarity to CDK2 substrates, particularly proteins involved in the origin of replication firing. PfCRK4 was required for initial and subsequent rounds of DNA replication during schizogony and, in addition, was essential for development in the mosquito vector. Our results identified an essential S-phase promoting factor of the unconventional P. falciparum cell cycle. PfCRK4 is required for both a prolonged period of the intraerythrocytic stage of Plasmodium infection, as well as for transmission, revealing a broad window for PfCRK4-targeted chemotherapeutics.

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

    PubMed

    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

  1. Functional analysis of Plasmodium falciparum merozoite antigens: implications for erythrocyte invasion and vaccine development.

    PubMed Central

    Cowman, Alan F; Baldi, Deborah L; Duraisingh, Manoj; Healer, Julie; Mills, Kerry E; O'Donnell, Rebecca A; Thompson, Jennifer; Triglia, Tony; Wickham, Mark E; Crabb, Brendan S

    2002-01-01

    Malaria is a major human health problem and is responsible for over 2 million deaths per year. It is caused by a number of species of the genus Plasmodium, and Plasmodium falciparum is the causative agent of the most lethal form. Consequently, the development of a vaccine against this parasite is a priority. There are a number of stages of the parasite life cycle that are being targeted for the development of vaccines. Important candidate antigens include proteins on the surface of the asexual merozoite stage, the form that invades the host erythrocyte. The development of methods to manipulate the genome of Plasmodium species has enabled the construction of gain-of-function and loss-of-function mutants and provided new strategies to analyse the role of parasite proteins. This has provided new information on the role of merozoite antigens in erythrocyte invasion and also allows new approaches to address their potential as vaccine candidates. PMID:11839179

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

    PubMed

    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.

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

    PubMed

    Zerihun, Tewodros; Degarege, Abraham; Erko, Berhanu

    2011-08-01

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

  4. Greater Endothelial Activation, Weibel-Palade Body Release and Host Inflammatory Response to Plasmodium vivax, compared with Plasmodium falciparum: A Prospective Study in Papua, Indonesia

    PubMed Central

    Yeo, Tsin W.; Lampah, Daniel A.; Tjitra, Emiliana; Piera, Kim; Gitawati, Retno; Kenangalem, Enny; Price, Ric N.; Anstey, Nicholas M.

    2015-01-01

    Pathogenic mechanisms underlying vivax malaria are poorly understood, with few studies comparing endothelial and inflammatory responses with falciparum malaria. In adults with uncomplicated vivax or falciparum malaria, we compared plasma measurements of endothelial Weibel-Palade body release (angiopoietin-2) and activation (ICAM-1, E-selectin), as well as selected cytokines. Despite a lower median parasite count, angiopoietin-2 concentrations were higher in patients with vivax malaria, compared with falciparum malaria. Per peripheral parasite, median plasma angiopoietin-2, ICAM-1, E-selectin, interleukin-6, and interleukin-10 concentrations were higher in patients with malaria due to Plasmodium vivax. P. vivax induces greater endothelial Weibel-Palade body release and activation and greater host inflammatory responses, compared with Plasmodium falciparum. PMID:20497057

  5. Drug Evaluation in the Plasmodium Falciparum-Aotus Model

    DTIC Science & Technology

    1996-03-01

    liver and erythrocytic stages of P. falciparum. If successful, it will establish for the first time that DNA vaccines can protect non- human primates, a...of the Institute of Laboratory Resources, National Research Council (NIH Publication No. 86-23, Revised 1985). For the protection of human subjects...essential that new drugs be evaluated in the preclinical Aotus model for their potential usefulness against human infections. Initially, antimalarial

  6. Drug Evaluation in the Plasmodium Falciparum-Aotus Model

    DTIC Science & Technology

    1996-03-01

    with. drug resistant P. falciparum, chloroquine resist ance-l R) was reversed by chlorpromazine and prochlorperazine. Both water-insoluble and soluble...Animals of the Institute of Laboratory Resources, National Research Council (NIH Publication No. 86-23, Revised 1985) For the protection of human sub...new drugs be evaluated in the preclinical Aotus model for their potential usefulness against human infections. Initially, antimalarial drug studies

  7. Pathogenicity Determinants of the Human Malaria Parasite Plasmodium falciparum Have Ancient Origins

    PubMed Central

    Brazier, Andrew J.; Avril, Marion; Bernabeu, Maria; Benjamin, Maxwell

    2017-01-01

    ABSTRACT Plasmodium falciparum, the most deadly of the human malaria parasites, is a member of the Laverania subgenus that also infects African Great Apes. The virulence of P. falciparum is related to cytoadhesion of infected erythrocytes in microvasculature, but the origin of dangerous parasite adhesion traits is poorly understood. To investigate the evolutionary history of the P. falciparum cytoadhesion pathogenicity determinant, we studied adhesion domains from the chimpanzee malaria parasite P. reichenowi. We demonstrate that the P. reichenowi var gene repertoire encodes cysteine-rich interdomain region (CIDR) domains which bind human CD36 and endothelial protein C receptor (EPCR) with the same levels of affinity and at binding sites similar to those bound by P. falciparum. Moreover, P. reichenowi domains interfere with the protective function of the activated protein C-EPCR pathway on endothelial cells, a presumptive virulence trait in humans. These findings provide evidence for ancient evolutionary origins of two key cytoadhesion properties of P. falciparum that contribute to human infection and pathogenicity. IMPORTANCE Cytoadhesion of P. falciparum-infected erythrocytes in the microcirculation is a major virulence determinant. P. falciparum is descended from a subgenus of parasites that also infect chimpanzees and gorillas and exhibits strict host species specificity. Despite their high genetic similarity to P. falciparum, it is unknown whether ape parasites encode adhesion properties similar to those of P. falciparum or are as virulent in their natural hosts. Consequently, it has been unclear when virulent adhesion traits arose in P. falciparum and how long they have been present in the parasite population. It is also unknown whether cytoadhesive interactions pose a barrier to cross-species transmission. We show that parasite domains from the chimpanzee malaria parasite P. reichenowi bind human receptors with specificity similar to that of P. falciparum

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

    PubMed

    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.

  9. Adherence of infected erythrocytes to venular endothelium selects for antigenic variants of Plasmodium falciparum.

    PubMed

    Biggs, B A; Anders, R F; Dillon, H E; Davern, K M; Martin, M; Petersen, C; Brown, G V

    1992-09-15

    Erythrocytes (E) infected with asexual forms of malaria parasites exhibit surface antigenic variation. In Plasmodium falciparum infections, the variant Ag is the P. falciparum E membrane protein 1 (PfEMP1). This molecule may also mediate the adherence of infected E to host venular endothelium. We show here that parasite lines selected for increased adherence to endothelial cells have undergone antigenic variation. Three adherent lines selected from the same P. falciparum clone reacted with the same agglutinating antiserum that failed to agglutinate the parental clone. Immunoprecipitation experiments with the agglutinating anti-serum demonstrated that the selected lines expressed cross-reactive forms of PfEMP1 that were of higher m.w. and antigenically distinct from PfEMP1 of the parental clone. When one of the adherent lines was cloned in the absence of selection, a range of variant antigenic types emerged with differing cytoadherence phenotypes. These findings show that selection for cytoadherence in vitro favors the emergence of antigenic variants of P. falciparum and suggest that the requirement for cytoadherence in vivo may restrict the range of antigenic variants of P. falciparum in natural infections.

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

    PubMed Central

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

    2012-01-01

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

  11. Evolution of genetic polymorphisms of Plasmodium falciparum merozoite surface protein (PfMSP) in Thailand.

    PubMed

    Kuesap, Jiraporn; Chaijaroenkul, Wanna; Ketprathum, Kanchanok; Tattiyapong, Puntanat; Na-Bangchang, Kesara

    2014-02-01

    Plasmodium falciparum malaria is a major public health problem in Thailand due to the emergence of multidrug resistance. The understanding of genetic diversity of malaria parasites is essential for developing effective drugs and vaccines. The genetic diversity of the merozoite surface protein-1 (PfMSP-1) and merozoite surface protein-2 (PfMSP-2) genes was investigated in a total of 145 P. falciparum isolates collected from Mae Sot District, Tak Province, Thailand during 3 different periods (1997-1999, 2005-2007, and 2009-2010). Analysis of genetic polymorphisms was performed to track the evolution of genetic change of P. falciparum using PCR. Both individual genes and their combination patterns showed marked genetic diversity during the 3 study periods. The results strongly support that P. falciparum isolates in Thailand are markedly diverse and patterns changed with time. These 2 polymorphic genes could be used as molecular markers to detect multiple clone infections and differentiate recrudescence from reinfection in P. falciparum isolates in Thailand.

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

    PubMed

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

    2005-04-01

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

  13. Variation in use of erythrocyte invasion pathways by Plasmodium falciparum mediates evasion of human inhibitory antibodies

    PubMed Central

    Persson, Kristina E.M.; McCallum, Fiona J.; Reiling, Linda; Lister, Nicole A.; Stubbs, Janine; Cowman, Alan F.; Marsh, Kevin; Beeson, James G.

    2007-01-01

    Antibodies that inhibit Plasmodium falciparum invasion of erythrocytes are believed to be an important component of immunity against malaria. During blood-stage infection, P. falciparum can use different pathways for erythrocyte invasion by varying the expression and/or utilization of members of 2 invasion ligand families: the erythrocyte-binding antigens (EBAs) and reticulocyte-binding homologs (PfRhs). Invasion pathways can be broadly classified into 2 groups based on the use of sialic acid (SA) on the erythrocyte surface by parasite ligands. We found that inhibitory antibodies are acquired by malaria-exposed Kenyan children and adults against ligands of SA-dependent and SA-independent invasion pathways, and the ability of antibodies to inhibit erythrocyte invasion depended on the pathway used by P. falciparum isolates. Differential inhibition of P. falciparum lines that varied in their use of specific EBA and PfRh proteins pointed to these ligand families as major targets of inhibitory antibodies. Antibodies against recombinant EBA and PfRh proteins were acquired in an age-associated manner, and inhibitory antibodies against EBA175 appeared prominent among some individuals. These findings suggest that variation in invasion phenotype might have evolved as a mechanism that facilitates immune evasion by P. falciparum and that a broad inhibitory response against multiple ligands may be required for effective immunity. PMID:18064303

  14. Branch point identification and sequence requirements for intron splicing in Plasmodium falciparum.

    PubMed

    Zhang, Xiaohong; Tolzmann, Caitlin A; Melcher, Martin; Haas, Brian J; Gardner, Malcolm J; Smith, Joseph D; Feagin, Jean E

    2011-11-01

    Splicing of mRNA is an ancient and evolutionarily conserved process in eukaryotic organisms, but intron-exon structures vary. Plasmodium falciparum has an extreme AT nucleotide bias (>80%), providing a unique opportunity to investigate how evolutionary forces have acted on intron structures. In this study, we developed an in vivo luciferase reporter splicing assay and employed it in combination with lariat isolation and sequencing to characterize 5' and 3' splicing requirements and experimentally determine the intron branch point in P. falciparum. This analysis indicates that P. falciparum mRNAs have canonical 5' and 3' splice sites. However, the 5' consensus motif is weakly conserved and tolerates nucleotide substitution, including the fifth nucleotide in the intron, which is more typically a G nucleotide in most eukaryotes. In comparison, the 3' splice site has a strong eukaryotic consensus sequence and adjacent polypyrimidine tract. In four different P. falciparum pre-mRNAs, multiple branch points per intron were detected, with some at U instead of the typical A residue. A weak branch point consensus was detected among 18 identified branch points. This analysis indicates that P. falciparum retains many consensus eukaryotic splice site features, despite having an extreme codon bias, and possesses flexibility in branch point nucleophilic attack.

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

    PubMed Central

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

    2012-01-01

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

  16. Global proteomic analysis of prenylated proteins in Plasmodium falciparum using an alkyne-modified isoprenoid analogue

    PubMed Central

    Suazo, Kiall F.; Schaber, Chad; Palsuledesai, Charuta C.; Odom John, Audrey R.; Distefano, Mark D.

    2016-01-01

    Severe malaria due to Plasmodium falciparum infection remains a serious threat to health worldwide and new therapeutic targets are highly desirable. Small molecule inhibitors of prenyl transferases, enzymes that catalyze the post-translational isoprenyl modifications of proteins, exhibit potent antimalarial activity. The antimalarial actions of prenyltransferase inhibitors indicate that protein prenylation is required for malaria parasite development. In this study, we used a chemical biology strategy to experimentally characterize the entire complement of prenylated proteins in the human malaria parasite. In contrast to the expansive mammalian and fungal prenylomes, we find that P. falciparum possesses a restricted set of prenylated proteins. The prenylome of P. falciparum is dominated by Rab GTPases, in addition to a small number of prenylated proteins that also appear to function primarily in membrane trafficking. Overall, we found robust experimental evidence for a total of only thirteen prenylated proteins in P. falciparum, with suggestive evidence for an additional two probable prenyltransferase substrates. Our work contributes to an increasingly complete picture of essential, post-translational hydrophobic modifications in blood-stage P. falciparum. PMID:27924931

  17. Global proteomic analysis of prenylated proteins in Plasmodium falciparum using an alkyne-modified isoprenoid analogue.

    PubMed

    Suazo, Kiall F; Schaber, Chad; Palsuledesai, Charuta C; Odom John, Audrey R; Distefano, Mark D

    2016-12-07

    Severe malaria due to Plasmodium falciparum infection remains a serious threat to health worldwide and new therapeutic targets are highly desirable. Small molecule inhibitors of prenyl transferases, enzymes that catalyze the post-translational isoprenyl modifications of proteins, exhibit potent antimalarial activity. The antimalarial actions of prenyltransferase inhibitors indicate that protein prenylation is required for malaria parasite development. In this study, we used a chemical biology strategy to experimentally characterize the entire complement of prenylated proteins in the human malaria parasite. In contrast to the expansive mammalian and fungal prenylomes, we find that P. falciparum possesses a restricted set of prenylated proteins. The prenylome of P. falciparum is dominated by Rab GTPases, in addition to a small number of prenylated proteins that also appear to function primarily in membrane trafficking. Overall, we found robust experimental evidence for a total of only thirteen prenylated proteins in P. falciparum, with suggestive evidence for an additional two probable prenyltransferase substrates. Our work contributes to an increasingly complete picture of essential, post-translational hydrophobic modifications in blood-stage P. falciparum.

  18. Mitochondrial genes support a common origin of rodent malaria parasites and Plasmodium falciparum's relatives infecting great apes.

    PubMed

    Blanquart, Samuel; Gascuel, Olivier

    2011-03-15

    Plasmodium falciparum is responsible for the most acute form of human malaria. Most recent studies demonstrate that it belongs to a monophyletic lineage specialized in the infection of great ape hosts. Several other Plasmodium species cause human malaria. They all belong to another distinct lineage of parasites which infect a wider range of primate species. All known mammalian malaria parasites appear to be monophyletic. Their clade includes the two previous distinct lineages of parasites of primates and great apes, one lineage of rodent parasites, and presumably Hepatocystis species. Plasmodium falciparum and great ape parasites are commonly thought to be the sister-group of all other mammal-infecting malaria parasites. However, some studies supported contradictory origins and found parasites of great apes to be closer to those of rodents, or to those of other primates. To distinguish between these mutually exclusive hypotheses on the origin of Plasmodium falciparum and its great ape infecting relatives, we performed a comprehensive phylogenetic analysis based on a data set of three mitochondrial genes from 33 to 84 malaria parasites. We showed that malarial mitochondrial genes have evolved slowly and are compositionally homogeneous. We estimated their phylogenetic relationships using Bayesian and maximum-likelihood methods. Inferred trees were checked for their robustness to the (i) site selection, (ii) assumptions of various probabilistic models, and (iii) taxon sampling. Our results robustly support a common ancestry of rodent parasites and Plasmodium falciparum's relatives infecting great apes. Our results refute the most common view of the origin of great ape malaria parasites, and instead demonstrate the robustness of a less well-established phylogenetic hypothesis, under which Plasmodium falciparum and its relatives infecting great apes are closely related to rodent parasites. This study sheds light on the evolutionary history of Plasmodium falciparum, a

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

    PubMed Central

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

    2017-01-01

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

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

    PubMed

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

    2017-01-01

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

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

    PubMed Central

    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 < 51.3 μmol/L) (10 cases); and patients who died due to accidents, whose liver histology was normal (the control group) (10 cases). The histopathology of the liver tissue was studied by routine histology method. Caspase-3 and nuclear factor kappa B (NF-κB) p65 expressions were determined using immunohistochemistry. Results The severity of liver histopathology, occurrence of apoptosis and NF-κB p65 activation in P. 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

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

    PubMed Central

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

    2005-01-01

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

  3. Evaluation of a rapid whole blood immunochromatographic assay for the diagnosis of Plasmodium falciparum and Plasmodium vivax malaria.

    PubMed

    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 < 0.001) and clinical severity of disease with P. vivax (p = 0.011). The ICT Malaria P.f/P.v test can be used in Sri Lanka in the absence of microscopists.

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

    PubMed

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

    2006-02-01

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

  5. A systematic classification of Plasmodium falciparum P-loop NTPases: structural and functional correlation

    PubMed Central

    Gangwar, Deepti; Kalita, Mridul K; Gupta, Dinesh; Chauhan, Virander S; Mohmmed, Asif

    2009-01-01

    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 the parasite that could

  6. Positive selection underlies the species-specific binding of Plasmodium falciparum RH5 to human basigin.

    PubMed

    Forni, Diego; Pontremoli, Chiara; Cagliani, Rachele; Pozzoli, Uberto; Clerici, Mario; Sironi, Manuela

    2015-09-01

    Plasmodium falciparum, the causative agent of the deadliest form of malaria, is a member of the Laverania subgenus, which includes ape-infecting parasites. P. falciparum is thought to have originated in gorillas, although infection is now restricted to humans. Laverania parasites display remarkable host-specificity, which is partially mediated by the interaction between parasite ligands and host receptors. We analyse the evolution of BSG (basigin) and GYPA (glycophorin A) in primates/hominins, as well as of their Plasmodium-encoded ligands, PfRH5 and PfEBA175. We show that, in primates, positive selection targeted two sites in BSG (F27 and H102), both involved in PfRH5 binding. A population genetics-phylogenetics approach detected the strongest selection for the gorilla lineage: one of the positively selected sites (K191) is a major determinant of PfRH5 binding affinity. Analysis of RH5 genes indicated episodic selection on the P. falciparum branch; the positively selected W447 site is known to stabilize the interaction with human basigin. Conversely, we detect no selection in the receptor-binding region of EBA175 in the P. falciparum lineage. Its host receptor, GYPA, shows evidence of positive selection in all hominid lineages; selected codons include glycosylation sites that modulate PfEBA175 binding affinity. Data herein provide an evolutionary explanation for species-specific binding of the PfRH5-BSG ligand-receptor pair and support the hypothesis that positive selection at these genes drove the host shift leading to the emergence of P. falciparum as a human pathogen. © 2015 John Wiley & Sons Ltd.

  7. PFE0565w, a Plasmodium falciparum Protein Expressed in Salivary Gland Sporozoites

    PubMed Central

    Schlarman, Maggie S.; Roberts, Renee N.; Kariuki, Michael M.; LaCrue, Alexis N.; Ou, Ruguang; Beerntsen, Brenda T.

    2012-01-01

    Because malaria is still a significant problem worldwide, additional control methods need to be developed. The Plasmodium sporozoite is a good target for control measures because it displays dual infectivity for both mosquito and vertebrate host tissues. The Plasmodium falciparum gene, PFE0565w, was chosen as a candidate for study based on data from PlasmoDB, the Plasmodium database, indicating that it is expressed both at the transcriptional and protein levels in sporozoites, likely encodes a putative surface protein, and may have a potential role in the invasion of host tissues. Additional sequence analysis shows that the PFE0565w protein has orthologs in other Plasmodium species, but none outside of the genus Plasmodium. PFE0565w expresses transcript during both the sporozoite and erythrocytic stages of the parasite life cycle, where an alternative transcript was discovered during the erythrocytic stages. Data show that transcript is not present during axenic exoerythrocytic stages. Despite transcript being present in several life cycle stages, the PFE0565w protein is present only during the salivary gland sporozoite stage. Because the PFE0565w protein is present in salivary gland sporozoites, it could be a novel candidate for a pre-erythrocytic stage vaccine. PMID:22665598

  8. An impossible journey? The development of Plasmodium falciparum NF54 in Culex quinquefasciatus.

    PubMed

    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.

  9. Identification and molecular characterization of an Alba-family protein from human malaria parasite Plasmodium falciparum

    PubMed Central

    Goyal, Manish; Alam, Athar; Iqbal, Mohd Shameel; Dey, Sumanta; Bindu, Samik; Pal, Chinmay; Banerjee, Anindyajit; Chakrabarti, Saikat; Bandyopadhyay, Uday

    2012-01-01

    We have investigated the DNA-binding nature as well as the function of a putative Alba (Acetylation lowers binding affinity) family protein (PfAlba3) from Plasmodium falciparum. PfAlba3 possesses DNA-binding property like Alba family proteins. PfAlba3 binds to DNA sequence non-specifically at the minor groove and acetylation lowers its DNA-binding affinity. The protein is ubiquitously expressed in all the erythrocytic stages of P. falciparum and it exists predominantly in the acetylated form. PfAlba3 inhibits transcription in vitro by binding to DNA. Plasmodium falciparum Sir2 (PfSir2A), a nuclear localized deacetylase interacts with PfAlba3 and deacetylates the lysine residue of N-terminal peptide of PfAlba3 specific for DNA binding. PfAlba3 is localized with PfSir2A in the periphery of the nucleus. Fluorescence in situ hybridization studies revealed the presence of PfAlba3 in the telomeric and subtelomeric regions. ChIP and ChIP ReChIP analyses further confirmed that PfAlba3 binds to the telomeric and subtelomeric regions as well as to var gene promoter. PMID:22006844

  10. Role of plasmepsin V in export of diverse protein families from the Plasmodium falciparum exportome.

    PubMed

    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.

  11. An FtsH protease is recruited to the mitochondrion of Plasmodium falciparum.

    PubMed

    Tanveer, Aiman; Allen, Stacey M; Jackson, Katherine E; Charan, Manish; Ralph, Stuart A; Habib, Saman

    2013-01-01

    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.

  12. The malarial parasite Plasmodium falciparum imports the human protein peroxiredoxin 2 for peroxide detoxification

    PubMed Central

    Koncarevic, Sasa; Rohrbach, Petra; Deponte, Marcel; Krohne, Georg; Prieto, Judith Helena; Yates, John; Rahlfs, Stefan; Becker, Katja

    2009-01-01

    Coevolution of the malarial parasite and its human host has resulted in a complex network of interactions contributing to the homeodynamics of the host-parasite unit. As a rapidly growing and multiplying organism, Plasmodium falciparum depends on an adequate antioxidant defense system that is efficient despite the absence of genuine catalase and glutathione peroxidase. Using different experimental approaches, we demonstrate that P. falciparum imports the human redox-active protein peroxiredoxin 2 (hPrx-2, hTPx1) into its cytosol. As shown by confocal microscopy and immunogold electron microscopy, hPrx-2 is also present in the Maurer's clefts, organelles that are described as being involved in parasite protein export. Enzyme kinetic analyses prove that hPrx-2 accepts Plasmodium cytosolic thioredoxin 1 as a reducing substrate. hPrx-2 accounts for roughly 50% of thioredoxin peroxidase activity in parasite extracts, thus indicating a functional role of hPrx-2 as an enzymatic scavenger of peroxides in the parasite. Under chloroquine treatment, a drug promoting oxidative stress, the abundance of hPrx-2 in the parasite increases significantly. P. falciparum has adapted to adopt the hPrx-2, thereby using the host protein for its own purposes. PMID:19666612

  13. The Potential of β Carbolin Alkaloids to Hinder Growth and Reverse Chloroquine Resistance in Plasmodium falciparum

    PubMed Central

    IBRAHEEM, Zaid O; ABDUL MAJID, Roslaini; MOHD NOOR, Sabariah; MOHD SIDEK, Hasidah; BASIR, Rusliza

    2015-01-01

    Background: Nowadays, scourge of malaria as a fatalistic disease has increased due to emergence of drug resistance and tolerance among different strains of Plasmodium falciparum. Emergence of chloroquine (CQ) resistance has worsened the calamity as CQ is still considered the most efficient, safe and cost effective drug among other antimalarials. This urged the scientists to search for other alternatives or sensitizers that may be able to augment CQ action and reverse its resistance. Method: Three β-carbolin derivatives, namely, harmalin, harmol and harmalol were tested for their anti-plasmodial and CQ resistance reversal effects against P. falciparum 3D7 and K1. SYBRE Green-1 based drug sensitivity assay and isobologram analysis were used to screen the mentioned effects respectively. Results: All of them showed moderate anti-plasmodium effect and harmalin was the most effective as compared to the others in reversing CQ resistance and tolerance. Conclusion: The mentioned phytochemicals are not ideal to be used as conventional antimalarials and only harmalin can be suggested to reverse CQ resistance in P. falciparum K1. PMID:26811724

  14. Plasmodium falciparum centromeres display a unique epigenetic makeup and cluster prior to and during schizogony.

    PubMed

    Hoeijmakers, Wieteke A M; Flueck, Christian; Françoijs, Kees-Jan; Smits, Arne H; Wetzel, Johanna; Volz, Jennifer C; Cowman, Alan F; Voss, Till; Stunnenberg, Hendrik G; Bártfai, Richárd

    2012-09-01

    Centromeres are essential for the faithful transmission of chromosomes to the next generation, therefore being essential in all eukaryotic organisms. The centromeres of Plasmodium falciparum, the causative agent of the most severe form of malaria, have been broadly mapped on most chromosomes, but their epigenetic composition remained undefined. Here, we reveal that the centromeric histone variant PfCENH3 occupies a 4-4.5 kb region on each P. falciparum chromosome, which is devoid of pericentric heterochromatin but harbours another histone variant, PfH2A.Z. These CENH3 covered regions pinpoint the exact position of the centromere on all chromosomes and revealed that all centromeric regions have similar size and sequence composition. Immunofluorescence assay of PfCENH3 strongly suggests that P. falciparum centromeres cluster to a single nuclear location prior to and during mitosis and cytokinesis but dissociate soon after invasion. In summary, we reveal a dynamic association of Plasmodium centromeres, which bear a unique epigenetic signature and conform to a strict structure. These findings suggest that DNA-associated and epigenetic elements play an important role in centromere establishment in this important human pathogen. © 2012 Blackwell Publishing Ltd.

  15. Biochemical and structural characterization of the apicoplast dihydrolipoamide dehydrogenase of Plasmodium falciparum

    PubMed Central

    Laine, Larissa M.; Biddau, Marco; Byron, Olwyn; Müller, Sylke

    2014-01-01

    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. PMID:25387830

  16. Plasmodium falciparum responds to amino acid starvation by entering into a hibernatory state.

    PubMed

    Babbitt, Shalon E; Altenhofen, Lindsey; Cobbold, Simon A; Istvan, Eva S; Fennell, Clare; Doerig, Christian; Llinás, Manuel; Goldberg, Daniel E

    2012-11-20

    The human malaria parasite Plasmodium falciparum is auxotrophic for most amino acids. Its amino acid needs are met largely through the degradation of host erythrocyte hemoglobin; however the parasite must acquire isoleucine exogenously, because this amino acid is not present in adult human hemoglobin. We report that when isoleucine is withdrawn from the culture medium of intraerythrocytic P. falciparum, the parasite slows its metabolism and progresses through its developmental cycle at a reduced rate. Isoleucine-starved parasites remain viable for 72 h and resume rapid growth upon resupplementation. Protein degradation during starvation is important for maintenance of this hibernatory state. Microarray analysis of starved parasites revealed a 60% decrease in the rate of progression through the normal transcriptional program but no other apparent stress response. Plasmodium parasites do not possess a TOR nutrient-sensing pathway and have only a rudimentary amino acid starvation-sensing eukaryotic initiation factor 2α (eIF2α) stress response. Isoleucine deprivation results in GCN2-mediated phosphorylation of eIF2α, but kinase-knockout clones still are able to hibernate and recover, indicating that this pathway does not directly promote survival during isoleucine starvation. We conclude that P. falciparum, in the absence of canonical eukaryotic nutrient stress-response pathways, can cope with an inconsistent bloodstream amino acid supply by hibernating and waiting for more nutrient to be provided.

  17. Characterisation of the Plasmodium falciparum Hsp70-Hsp90 organising protein (PfHop).

    PubMed

    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. Baseline in vitro efficacy of ACT component drugs on Plasmodium falciparum clinical isolates from Mali.

    PubMed

    Kaddouri, Halima; Djimdé, Abdoulaye; Dama, Souleymane; Kodio, Aly; Tekete, Mamadou; Hubert, Véronique; Koné, Aminatou; Maiga, Hamma; Yattara, Oumar; Fofana, Bakary; Sidibe, Bakary; Sangaré, Cheick P O; Doumbo, Ogobara; Le Bras, Jacques

    2008-06-01

    In vitro susceptibility to antimalarial drugs of Malian Plasmodium falciparum isolates collected between 2004 and 2006 was studied. Susceptibility to chloroquine and to three artemisinin-based combination therapy (ACT) component drugs was assessed as a first, to our knowledge, in vitro susceptibility study in Mali. Overall 96 Malian isolates (51 from around Bamako and 45 collected from French travellers returning from Mali) were cultivated in a CO(2) incubator. Fifty percent inhibitory concentrations (IC(50)s) were measured by either hypoxanthine incorporation or Plasmodium lactate dehydrogenase (pLDH) ELISA. Although the two sets of data were generated with different methods, the global IC(50) distributions showed parallel trends. A good concordance of resistance phenotype with pfcrt 76T mutant genotype was found within the sets of clinical isolates tested. We confirm a high prevalence of P. falciparum in vitro resistance to chloroquine in Mali (60-69%). While some isolates showed IC(50)s close to the cut-off for resistance to monodesethylamodiaquine, no decreased susceptibility to dihydroartemisinin or lumefantrine was detected. This study provides baseline data for P. falciparum in vitro susceptibility to ACT component drugs in Mali.

  19. Vectored antibody gene delivery protects against Plasmodium falciparum sporozoite challenge in mice.

    PubMed

    Deal, Cailin; Balazs, Alejandro B; Espinosa, Diego A; Zavala, Fidel; Baltimore, David; Ketner, Gary

    2014-08-26

    Malaria caused by Plasmodium falciparum kills nearly one million children each year and imposes crippling economic burdens on families and nations worldwide. No licensed vaccine exists, but infection can be prevented by antibodies against the circumsporozoite protein (CSP), the major surface protein of sporozoites, the form of the parasite injected by mosquitoes. We have used vectored immunoprophylaxis (VIP), an adeno-associated virus-based technology, to introduce preformed antibody genes encoding anti-P. falciparum CSP mAb into mice. VIP vector-transduced mice exhibited long-lived mAb expression at up to 1,200 µg/mL in serum, and up to 70% were protected from both i.v. and mosquito bite challenge with transgenic Plasmodium berghei rodent sporozoites that incorporate the P. falciparum target of the mAb in their CSP. Serum antibody levels and protection from mosquito bite challenge were dependent on the dose of the VIP vector. All individual mice expressing CSP-specific mAb 2A10 at 1 mg/mL or more were completely protected, suggesting that in this model system, exceeding that threshold results in consistent sterile protection. Our results demonstrate the potential of VIP as a path toward the elusive goal of immunization against malaria.

  20. Characterization of a Plasmodium falciparum erythrocyte-binding protein paralogous to EBA-175

    PubMed Central

    Mayer, D. C. Ghislaine; Kaneko, Osamu; Hudson-Taylor, Diana E.; Reid, Marion E.; Miller, Louis H.

    2001-01-01

    A member of a Plasmodium receptor family for erythrocyte invasion was identified on chromosome 13 from the Plasmodium falciparum genome sequence of the Sanger Centre (Cambridge, U.K.). The protein (named BAEBL) has homology to EBA-175, a P. falciparum receptor that binds specifically to sialic acid and the peptide backbone of glycophorin A on erythrocytes. Both EBA-175 and BAEBL localize to the micronemes, organelles at the invasive ends of the parasites that contain other members of the family. Like EBA-175, the erythrocyte receptor for BAEBL is destroyed by neuraminidase and trypsin, indicating that the erythrocyte receptor is a sialoglycoprotein. Its specificity, however, differs from that of EBA-175 in that BAEBL can bind to erythrocytes that lack glycophorin A, the receptor for EBA-175. It has reduced binding to erythrocytes with the Gerbich mutation found in another erythrocyte, sialoglycoprotein (glycophorin C/D). The interest in BAEBL's reduced binding to Gerbich erythrocytes derives from the high frequency of the Gerbich phenotype in some regions of Papua New Guinea where P. falciparum is hyperendemic. PMID:11309486

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

    PubMed Central

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

    2008-01-01

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

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

    PubMed

    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.

  3. Plasmodium falciparum-Derived Uric Acid Precipitates Induce Maturation of Dendritic Cells

    PubMed Central

    van de Hoef, Diana L.; Coppens, Isabelle; Holowka, Thomas; Ben Mamoun, Choukri; Branch, OraLee; Rodriguez, Ana

    2013-01-01

    Malaria is characterized by cyclical fevers and high levels of inflammation, and while an early inflammatory response contributes to parasite clearance, excessive and persistent inflammation can lead to severe forms of the disease. Here, we show that Plasmodium falciparum-infected erythrocytes contain uric acid precipitates in the cytoplasm of the parasitophorous vacuole, which are released when erythrocytes rupture. Uric acid precipitates are highly inflammatory molecules that are considered a danger signal for innate immunity and are the causative agent in gout. We determined that P. falciparum-derived uric acid precipitates induce maturation of human dendritic cells, increasing the expression of cell surface co-stimulatory molecules such as CD80 and CD86, while decreasing human leukocyte antigen-DR expression. In accordance with this, uric acid accounts for a significant proportion of the total stimulatory activity induced by parasite-infected erythrocytes. Moreover, the identification of uric acid precipitates in P. falciparum- and P. vivax-infected erythrocytes obtained directly from malaria patients underscores the in vivo and clinical relevance of our findings. Altogether, our data implicate uric acid precipitates as a potentially important contributor to the innate immune response to Plasmodium infection and may provide a novel target for adjunct therapies. PMID:23405174

  4. Malarial parasite diversity in chimpanzees: the value of comparative approaches to ascertain the evolution of Plasmodium falciparum antigens

    PubMed Central

    2013-01-01

    Background Plasmodium falciparum shares its most recent common ancestor with parasites found in African apes; these species constitute the so-called Laverania clade. In this investigation, the evolutionary history of Plasmodium lineages found in chimpanzees (Pan troglodytes) was explored. Methods Here, the remainders of 74 blood samples collected as part of the chimpanzees’ routine health examinations were studied. For all positive samples with parasite lineages belonging to the Laverania clade, the complete mitochondrial genome (mtDNA), the gene encoding dihydrofolate reductase-thymidylate synthase (dhfr-ts), the chloroquine resistance transporter (Pfcrt), the circumsporozoite protein (csp), merozoite surface protein 2 (msp2), and the DBL-1 domain from var2CSA were amplified, cloned, and sequenced. Other Plasmodium species were included in the mtDNA, dhfr-ts, and csp analyses. Phylogenetic and evolutionary genetic analyses were performed, including molecular clock analyses on the mtDNA. Results/Conclusions Nine chimpanzees were malaria positive (12.2%); four of those infections were identified as P. falciparum, two as a Plasmodium reichenowi-like parasite or Plasmodium sp., one as Plasmodium gaboni, and two as Plasmodium malariae. All P. falciparum isolates were resistant to chloroquine indicating that the chimpanzees acquired such infections from humans in recent times. Such findings, however, are not sufficient for implicating chimpanzees as an animal reservoir for P. falciparum. Timing estimates support that the Laverania clade has co-existed with hominids for a long-period of time. The proposed species P. gaboni, Plasmodium billbrayi, and Plasmodium billcollinsi are monophyletic groups supporting that they are indeed different species. An expanded CSP phylogeny is presented, including all the Laverania species and other malarial parasites. Contrasting with other Plasmodium, the Laverania csp exhibits great conservation at the central tandem repeat region

  5. Malarial parasite diversity in chimpanzees: the value of comparative approaches to ascertain the evolution of Plasmodium falciparum antigens.

    PubMed

    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

  6. Plasmodium falciparum MAEBL is a unique member of the ebl family.

    PubMed

    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.

  7. Single tryptophan of disordered loop from Plasmodium falciparum purine nucleoside phosphorylase: involvement in catalysis and microenvironment.

    PubMed

    Suthar, Manish Kumar; Verma, Anita; Doharey, Pawan Kumar; Singh, Shiv Vardan; Saxena, Jitendra Kumar

    2013-06-01

    Among various tropical diseases, malaria is a major life-threatening disease caused by Plasmodium parasite. Plasmodium falciparum is responsible for the deadliest form of malaria, so-called cerebral malaria. Purine nucleoside phosphorylase from P. falciparum is a homohexamer containing single tryptophan residue per subunit that accepts inosine and guanosine but not adenosine for its activity. This enzyme has been exploited as drug target against malaria disease. It is important to draw together significant knowledge about inherent properties of this enzyme which will be helpful in better understanding of this drug target. The enzyme shows disorder to order transition during catalysis. The single tryptophan residue residing in conserved region of transition loop is present in purine nucleoside phosphorylases throughout the Plasmodium genus. This active site loop motif is conserved among nucleoside phosphorylases from apicomplexan parasites. Modification of tryptophan residue by N-bromosuccinamide resulted in complete loss of activity showing its importance in catalysis. Inosine was not able to protect enzyme against N-bromosuccinamide modification. Extrinsic fluorescence studies revealed that tryptophan might not be involved in substrate binding. The tryptophan residue localised in electronegative environment showed collisional and static quenching in the presence of quenchers of different polarities.

  8. DNA repair mechanisms and their biological roles in the malaria parasite Plasmodium falciparum.

    PubMed

    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.

  9. Functional genomic technologies applied to the control of the human malaria parasite, Plasmodium falciparum.

    PubMed

    Carucci, D J

    2001-05-01

    Infection with any of the four species of Plasmodium single cell parasites that infects humans causes the clinical disease, malaria. Of these, it is Plasmodium falciparum that is responsible for the majority of the 1.5-2.3 million deaths due to this disease each year. Worldwide there are between 300-500 million cases of malaria annually. To date there is no licensed vaccine and resistance to most of the available drugs used to prevent and/or treat malaria is spreading. There is therefore an urgent need to develop new and effective drugs and vaccines against this devastating parasite. We have outlined a strategy using a combination of DNA-based vaccines and the data derived from the soon-to-be completed P. falciparum genome and the genomes of other species of Plasmodium to develop new vaccines against malaria. Much of the technology that we are developing for vaccine target identification is directly applicable to the identification of potential targets for drug discovery. The publicly available genome sequence data also provides a means for researchers whose focus may not be primarily malaria to leverage their research on cancer, yeast biology and other research areas to the biological problems of malaria.

  10. DNA Repair Mechanisms and Their Biological Roles in the Malaria Parasite Plasmodium falciparum

    PubMed Central

    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

  11. In vivo responses to antimalarials by Plasmodium falciparum and Plasmodium vivax from isolated Gag Island off northwest Irian Jaya, Indonesia.

    PubMed

    Fryauff, D J; Sumawinata, I; Purnomo; Richie, T L; Tjitra, E; Bangs, M J; Kadir, A; Ingkokusumo, G

    1999-04-01

    There is renewed interest in the rich nickel and cobalt deposits of Pulau Gag, an isolated but malarious island off the northwest coast of Irian Jaya. In preparation for an expanded workforce, an environmental assessment of malaria risk was made, focusing upon malaria prevalence in the small indigenous population, and the in vivo sensitivity of Plasmodium falciparum and P. vivax to chloroquine (CQ) and sulfadoxine/pyrimethamine (S/P), the respective first- and second-line drugs for uncomplicated malaria in Indonesia. During April-June 1997, mildly symptomatic or asymptomatic malaria infections were found in 24% of 456 native residents. Infections by P. falciparum accounted for 60% of the cases. Respective day 28 cure rates for CQ (10 mg base/kg on days 0 and 1; 5 mg/kg on day 2) in children and adults were 14% and 55% (P < 0.005). Type RII and RIII resistance characterized only 5% of the CQ failures. Re-treatment of 36 P. falciparum CQ treatment failures with S/P (25 mg/kg and 1.25 mg/kg, respectively) demonstrated rapid clearance and complete sensitivity during the 28-day follow-up period. More than 97% of the P. vivax malaria cases treated with CQ cleared parasitemia within 48 hr. Three cases of P. vivax malaria recurred between days 21 and 28, but against low drug levels in the blood. The low frequency of RII and RIII P. falciparum resistance to CQ, the complete sensitivity of this species to S/P, and the absence of CQ resistance by P. vivax are in contrast to in vivo and in vitro test results from sites on mainland Irian Jaya.

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

    PubMed

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

    2013-02-01

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

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

    PubMed Central

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

    2013-01-01

    We describe here the results of antimalarial therapeutic efficacy studies conducted in Cambodia from 2008 to 2010. A total of 15 studies in four sentinel sites were conducted using dihydroartemisinin-piperaquine (DP) for the treatment of Plasmodium falciparum infection and chloroquine (CQ) and DP for the treatment of P. vivax infection. All studies were performed according to the standard World Health Organization protocol for the assessment of antimalarial treatment efficacy. Among the studies of DP for the treatment of P. falciparum, an increase in treatment failure was observed in the western provinces. In 2010, the PCR-corrected treatment failure rates for DP on day 42 were 25% (95% confidence interval [CI] = 10 to 51%) in Pailin and 10.7% (95% CI = 4 to 23%) in Pursat, while the therapeutic efficacy of DP remained high (100%) in Ratanakiri and Preah Vihear provinces, located in northern and eastern Cambodia. For the studies of P. vivax, the day 28 uncorrected treatment failure rate among patients treated with CQ ranged from 4.4 to 17.4%; DP remained 100% effective in all sites. Further study is required to investigate suspected P. falciparum resistance to piperaquine in western Cambodia; the results of in vitro and molecular studies were not found to support the therapeutic efficacy findings. The emergence of artemisinin resistance in this region has likely put additional pressure on piperaquine. Although DP appears to be an appropriate new first-line treatment for P. vivax in Cambodia, alternative treatments are urgently needed for P. falciparum-infected patients in western Cambodia. PMID:23208711

  14. The ferredoxin-NADP+ reductase/ferredoxin electron transfer system of Plasmodium falciparum.

    PubMed

    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.

  15. Biosynthesis of GDP-fucose and Other Sugar Nucleotides in the Blood Stages of Plasmodium falciparum*

    PubMed Central

    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

  16. Genetic diversity of the merozoite surface protein-3 gene in Plasmodium falciparum populations in Thailand.

    PubMed

    Pattaradilokrat, Sittiporn; Sawaswong, Vorthon; Simpalipan, Phumin; Kaewthamasorn, Morakot; Siripoon, Napaporn; Harnyuttanakorn, Pongchai

    2016-10-21

    An effective malaria vaccine is an urgently needed tool to fight against human malaria, the most deadly parasitic disease of humans. One promising candidate is the merozoite surface protein-3 (MSP-3) of Plasmodium falciparum. This antigenic protein, encoded by the merozoite surface protein (msp-3) gene, is polymorphic and classified according to size into the two allelic types of K1 and 3D7. A recent study revealed that both the K1 and 3D7 alleles co-circulated within P. falciparum populations in Thailand, but the extent of the sequence diversity and variation within each allelic type remains largely unknown. The msp-3 gene was sequenced from 59 P. falciparum samples collected from five endemic areas (Mae Hong Son, Kanchanaburi, Ranong, Trat and Ubon Ratchathani) in Thailand and analysed for nucleotide sequence diversity, haplotype diversity and deduced amino acid sequence diversity. The gene was also subject to population genetic analysis (F st ) and neutrality tests (Tajima's D, Fu and Li D* and Fu and Li' F* tests) to determine any signature of selection. The sequence analyses revealed eight unique DNA haplotypes and seven amino acid sequence variants, with a haplotype and nucleotide diversity of 0.828 and 0.049, respectively. Neutrality tests indicated that the polymorphism detected in the alanine heptad repeat region of MSP-3 was maintained by positive diversifying selection, suggesting its role as a potential target of protective immune responses and supporting its role as a vaccine candidate. Comparison of MSP-3 variants among parasite populations in Thailand, India and Nigeria also inferred a close genetic relationship between P. falciparum populations in Asia. This study revealed the extent of the msp-3 gene diversity in P. falciparum in Thailand, providing the fundamental basis for the better design of future blood stage malaria vaccines against P. falciparum.

  17. Increasing Plasmodium falciparum malaria in southwest London: a 25 year observational study

    PubMed Central

    Williams, J; Chitre, M; Sharland, M

    2002-01-01

    Aims: To identify changes in the presenting number and species of imported malaria in children in southwest London. Methods: A prospective single observer study over 25 years (1975–99) of all cases of paediatric malaria seen at St George's Hospital. Results: A confirmed diagnosis was made in 249 children (56% boys; 44% girls; median age 8.0 years). Of these, 53% were UK residents and 44% were children travelling to the UK. A significant increase was noted in the number of cases over the 25 years (1975–79: mean 4.8 cases/year; 1990–99: mean 13.7 cases/year). Over the 25 years Plasmodium falciparum was seen in 77%, P vivax in 14%, P ovale in 6%, and P malariae in 3% of cases. P falciparum had increased in frequency (1975–79: P falciparum 50%, P vivax 50%; 1990–99: P falciparum 82%, P vivax 6%), associated with an increase in the proportion of children acquiring their infection in sub-Saharan Africa. Median time between arrival in the UK to the onset of fever was: P falciparum, 5 days; P ovale, 25 days; P malariae, 37 days; and P vivax, 62 days. Median time interval between the onset of fever to commencement of treatment was 4 days. This had not improved over the 25 year period. Only 41% of UK resident children presenting to hospital had taken prophylaxis and the overall number of symptomatic children taking no prophylaxis was increasing. Conclusion: Imported childhood P falciparum malaria is increasing in southwest London associated with increasing travel from sub-Saharan Africa. Over the 25 year period there has been no improvement in chemoprophylaxis rates or time to diagnosis. PMID:12023177

  18. Temporal Association of Acute Hepatitis A and Plasmodium falciparum Malaria in Children

    PubMed Central

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

    2011-01-01

    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. PMID:21754982

  19. Assessing functional annotation transfers with inter-species conserved coexpression: application to Plasmodium falciparum

    PubMed Central

    2010-01-01

    Background Plasmodium falciparum is the main causative agent of malaria. Of the 5 484 predicted genes of P. falciparum, about 57% do not have sufficient sequence similarity to characterized genes in other species to warrant functional assignments. Non-homology methods are thus needed to obtain functional clues for these uncharacterized genes. Gene expression data have been widely used in the recent years to help functional annotation in an intra-species way via the so-called Guilt By Association (GBA) principle. Results We propose a new method that uses gene expression data to assess inter-species annotation transfers. Our approach starts from a set of likely orthologs between a reference species (here S. cerevisiae and D. melanogaster) and a query species (P. falciparum). It aims at identifying clusters of coexpressed genes in the query species whose coexpression has been conserved in the reference species. These conserved clusters of coexpressed genes are then used to assess annotation transfers between genes with low sequence similarity, enabling reliable transfers of annotations from the reference to the query species. The approach was used with transcriptomic data sets of P. falciparum, S. cerevisiae and D. melanogaster, and enabled us to propose with high confidence new/refined annotations for several dozens hypothetical/putative P. falciparum genes. Notably, we revised the annotation of genes involved in ribosomal proteins and ribosome biogenesis and assembly, thus highlighting several potential drug targets. Conclusions Our approach uses both sequence similarity and gene expression data to help inter-species gene annotation transfers. Experiments show that this strategy improves the accuracy achieved when using solely sequence similarity and outperforms the accuracy of the GBA approach. In addition, our experiments with P. falciparum show that it can infer a function for numerous hypothetical genes. PMID:20078859

  20. Biosynthesis of GDP-fucose and other sugar nucleotides in the blood stages of Plasmodium falciparum.

    PubMed

    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.

  1. Cellular Effects of Curcumin on Plasmodium falciparum Include Disruption of Microtubules

    PubMed Central

    Chakrabarti, Rimi; Rawat, Parkash S.; Cooke, Brian M.; Coppel, Ross L.; Patankar, Swati

    2013-01-01

    Curcumin has been widely investigated for its myriad cellular effects resulting in reduced proliferation of various eukaryotic cells including cancer cells and the human malaria parasite Plasmodium falciparum. Studies with human cancer cell lines HT-29, Caco-2, and MCF-7 suggest that curcumin can bind to tubulin and induce alterations in microtubule structure. Based on this finding, we investigated whether curcumin has any effect on P. falciparum microtubules, considering that mammalian and parasite tubulin are 83% identical. IC50 of curcumin was found to be 5 µM as compared to 20 µM reported before. Immunofluorescence images of parasites treated with 5 or 20 µM curcumin showed a concentration-dependent effect on parasite microtubules resulting in diffuse staining contrasting with the discrete hemispindles and subpellicular microtubules observed in untreated parasites. The effect on P. falciparum microtubules was evident only in the second cycle for both concentrations tested. This diffuse pattern of tubulin fluorescence in curcumin treated parasites was similar to the effect of a microtubule destabilizing drug vinblastine on P. falciparum. Molecular docking predicted the binding site of curcumin at the interface of alpha and beta tubulin, similar to another destabilizing drug colchicine. Data from predicted drug binding is supported by results from drug combination assays showing antagonistic interactions between curcumin and colchicine, sharing a similar binding site, and additive/synergistic interactions of curcumin with paclitaxel and vinblastine, having different binding sites. This evidence suggests that cellular effects of curcumin are at least, in part, due to its perturbing effect on P. falciparum microtubules. The action of curcumin, both direct and indirect, on P. falciparum microtubules is discussed. PMID:23505424

  2. Cellular effects of curcumin on Plasmodium falciparum include disruption of microtubules.

    PubMed

    Chakrabarti, Rimi; Rawat, Parkash S; Cooke, Brian M; Coppel, Ross L; Patankar, Swati

    2013-01-01

    Curcumin has been widely investigated for its myriad cellular effects resulting in reduced proliferation of various eukaryotic cells including cancer cells and the human malaria parasite Plasmodium falciparum. Studies with human cancer cell lines HT-29, Caco-2, and MCF-7 suggest that curcumin can bind to tubulin and induce alterations in microtubule structure. Based on this finding, we investigated whether curcumin has any effect on P. falciparum microtubules, considering that mammalian and parasite tubulin are 83% identical. IC50 of curcumin was found to be 5 µM as compared to 20 µM reported before. Immunofluorescence images of parasites treated with 5 or 20 µM curcumin showed a concentration-dependent effect on parasite microtubules resulting in diffuse staining contrasting with the discrete hemispindles and subpellicular microtubules observed in untreated parasites. The effect on P. falciparum microtubules was evident only in the second cycle for both concentrations tested. This diffuse pattern of tubulin fluorescence in curcumin treated parasites was similar to the effect of a microtubule destabilizing drug vinblastine on P. falciparum. Molecular docking predicted the binding site of curcumin at the interface of alpha and beta tubulin, similar to another destabilizing drug colchicine. Data from predicted drug binding is supported by results from drug combination assays showing antagonistic interactions between curcumin and colchicine, sharing a similar binding site, and additive/synergistic interactions of curcumin with paclitaxel and vinblastine, having different binding sites. This evidence suggests that cellular effects of curcumin are at least, in part, due to its perturbing effect on P. falciparum microtubules. The action of curcumin, both direct and indirect, on P. falciparum microtubules is discussed.

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

    PubMed Central

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

    1998-01-01

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

  4. The therapeutic efficacy of sulfadoxine/pyrimethamine against Plasmodium falciparum in Yemen.

    PubMed

    Al-Kabsi, Abdulgodos M; Al-Shamahy, Hassan A; Al-Harazy, Abdulilah Hussein; Harmal, Nabil S

    2009-01-01

    The aim of this study was to determine the sensitivities of Plasmodium falciparum clinical isolates to sulfadoxine/pyrimethamine (SP) using in vivo and in vitro methods. In vivo and Mark III in-vitro test techniques according to World Health Organization protocols of antimalarial drug tests were used to determine the SP susceptibility of the P. falciparum isolates from 100 malaria patients of both sexes between the ages of 3.5 and 45 years and living in Tihamah, Yemen. The study was conducted between 19 March and 12 May 2005. In vivo: no therapeutic failure occurred; the clinical outcome matched the parasitological response and all patients were parasite free by day 3 and remained so on days 7, 14 and 28. In vitro: all the P. falciparum isolates developed to schizonts in zero-drug-concentration wells, but were inhibited in 40 nmol/l of SP; the mean effective concentration (EC(99)) was 67.17 nmol/l. Our findings showed that the SP combination is still effective for the treatment of uncomplicated P. falciparum malaria in Yemen. It is recommended that further studies be carried out to address the importance of dihydropteroate synthetase/dihydrofolate reductase mutations as predictive markers of sulfadoxine/pyrimethamine resistance in Yemen. Copyright 2008 S. Karger AG, Basel.

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

    PubMed Central

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

    1998-01-01

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

  6. Expression of cleaved caspase-3 in renal tubular cells in Plasmodium falciparum malaria patients.

    PubMed

    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.

  7. Hemoglobinopathic Erythrocytes Affect the Intraerythrocytic Multiplication of Plasmodium falciparum In Vitro

    PubMed Central

    Glushakova, Svetlana; Balaban, Amanda; McQueen, Philip G.; Coutinho, Rosane; Miller, Jeffery L.; Nossal, Ralph; Fairhurst, Rick M.; Zimmerberg, Joshua

    2014-01-01

    Background. The mechanisms by which α-thalassemia and sickle cell traits confer protection from severe Plasmodium falciparum malaria are not yet fully elucidated. We hypothesized that hemoglobinopathic erythrocytes reduce the intraerythrocytic multiplication of P. falciparum, potentially delaying the development of life-threatening parasite densities until parasite clearing immunity is achieved. Methods. We developed a novel in vitro assay to quantify the number of merozoites released from an individual schizont, termed the “intraerythrocytic multiplication factor” (IMF). Results. P. falciparum (3D7 line) schizonts produce variable numbers of merozoites in all erythrocyte types tested, with median IMFs of 27, 27, 29, 23, and 23 in control, HbAS, HbSS, and α- and β-thalassemia trait erythrocytes, respectively. IMF correlated strongly (r2 = 0.97; P < .001) with mean corpuscular hemoglobin concentration, and varied significantly with mean corpuscular volume and hemoglobin content. Reduction of IMFs in thalassemia trait erythrocytes was confirmed using clinical parasite isolates with different IMFs. Mathematical modeling of the effect of IMF on malaria progression indicates that the lower IMF in thalassemia trait erythrocytes limits parasite density and anemia severity over the first 2 weeks of parasite replication. Conclusions. P. falciparum IMF, a parasite heritable virulence trait, correlates with erythrocyte indices and is reduced in thalassemia trait erythrocytes. Parasite IMF should be examined in other low-indices erythrocytes. PMID:24688070

  8. Plasmodium falciparum Mating Patterns and Mosquito Infectivity of Natural Isolates of Gametocytes

    PubMed Central

    Morlais, Isabelle; Nsango, Sandrine E.; Toussile, Wilson; Abate, Luc; Annan, Zeinab; Tchioffo, Majoline T.; Cohuet, Anna; Awono-Ambene, Parfait H.; Fontenille, Didier; Rousset, François; Berry, Antoine

    2015-01-01

    Plasmodium falciparum infections in malaria endemic areas often harbor multiple clones of parasites. However, the transmission success of the different genotypes within the mosquito vector has remained elusive so far. The genetic diversity of malaria parasites was measured by using microsatellite markers in gametocyte isolates from 125 asymptomatic carriers. For a subset of 49 carriers, the dynamics of co-infecting genotypes was followed until their development within salivary glands. Also, individual oocysts from midguts infected with blood from 9 donors were genotyped to assess mating patterns. Multiplicity of infection (MOI) was high both in gametocyte isolates and sporozoite populations, reaching up to 10 genotypes. Gametocyte isolates with multiple genotypes gave rise to lower infection prevalence and intensity. Fluctuations of genotype number occurred during the development within the mosquito and sub-patent genotypes, not detected in gametocyte isolates, were identified in the vector salivary glands. The inbreeding coefficient Fis was positively correlated to the oocyst loads, suggesting that P. falciparum parasites use different reproductive strategies according to the genotypes present in the gametocyte isolate. The number of parasite clones within an infection affects the transmission success and the mosquito has an important role in maintaining P. falciparum genetic diversity. Our results emphasize the crucial importance of discriminating between the different genotypes within an infection when studying the A. gambiae natural resistance to P. falciparum, and the need to monitor parasite diversity in areas where malaria control interventions are implemented. PMID:25875840

  9. Immunogenicity and in vitro Protective Efficacy of a Recombinant Multistage Plasmodium falciparum Candidate Vaccine

    NASA Astrophysics Data System (ADS)

    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.

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

    PubMed Central

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

    2006-01-01

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

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

    PubMed

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

    2006-03-01

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

  12. Interrogating a Hexokinase-Selected Small-Molecule Library for Inhibitors of Plasmodium falciparum Hexokinase

    PubMed Central

    Harris, Michael T.; Walker, Dawn M.; Drew, Mark E.; Mitchell, William G.; Dao, Kevin; Schroeder, Chad E.; Flaherty, Daniel P.; Weiner, Warren S.; Golden, Jennifer E.

    2013-01-01

    Parasites in the genus Plasmodium cause disease throughout the tropic and subtropical regions of the world. P. falciparum, one of the deadliest species of the parasite, relies on glycolysis for the generation of ATP while it inhabits the mammalian red blood cell. The first step in glycolysis is catalyzed by hexokinase (HK). While the 55.3-kDa P. falciparum HK (PfHK) shares several biochemical characteristics with mammalian HKs, including being inhibited by its products, it has limited amino acid identity (∼26%) to the human HKs, suggesting that enzyme-specific therapeutics could be generated. To that end, interrogation of a selected small-molecule library of HK inhibitors has identified a class of PfHK inhibitors, isobenzothiazolinones, some of which have 50% inhibitory concentrations (IC50s) of <1 μM. Inhibition was reversible by dilution but not by treatment with a reducing agent, suggesting that the basis for enzyme inactivation was not covalent association with the inhibitor. Lastly, six of these compounds and the related molecule ebselen inhibited P. falciparum growth in vitro (50% effective concentration [EC50] of ≥0.6 and <6.8 μM). These findings suggest that the chemotypes identified here could represent leads for future development of therapeutics against P. falciparum. PMID:23716053

  13. Complete Plasmodium falciparum liver-stage development in liver-chimeric mice

    PubMed Central

    Vaughan, Ashley M.; Mikolajczak, Sebastian A.; Wilson, Elizabeth M.; Grompe, Markus; Kaushansky, Alexis; Camargo, Nelly; Bial, John; Ploss, Alexander; Kappe, Stefan H.I.

    2012-01-01

    Plasmodium falciparum, which causes the most lethal form of human malaria, replicates in the host liver during the initial stage of infection. However, in vivo malaria liver-stage (LS) studies in humans are virtually impossible, and in vitro models of LS development do not reconstitute relevant parasite growth conditions. To overcome these obstacles, we have adopted a robust mouse model for the study of P. falciparum LS in vivo: the immunocompromised and fumarylacetoacetate hydrolase–deficient mouse (Fah–/–, Rag2–/–, Il2rg–/–, termed the FRG mouse) engrafted with human hepatocytes (FRG huHep). FRG huHep mice supported vigorous, quantifiable P. falciparum LS development that culminated in complete maturation of LS at approximately 7 days after infection, providing a relevant model for LS development in humans. The infections allowed observations of previously unknown expression of proteins in LS, including P. falciparum translocon of exported proteins 150 (PTEX150) and exported protein-2 (EXP-2), components of a known parasite protein export machinery. LS schizonts exhibited exoerythrocytic merozoite formation and merosome release. Furthermore, FRG mice backcrossed to the NOD background and repopulated with huHeps and human red blood cells supported reproducible transition from LS infection to blood-stage infection. Thus, these mice constitute reliable models to study human LS directly in vivo and demonstrate utility for studies of LS–to–blood-stage transition of a human malaria parasite. PMID:22996664

  14. A densely overlapping gene fragmentation approach improves yeast two-hybrid screens for Plasmodium falciparum proteins.

    PubMed

    Brown, Hakeenah F; Wang, Ling; Khadka, Sudip; Fields, Stanley; LaCount, Douglas J

    2011-01-01

    Use of the yeast two-hybrid assay to study Plasmodium falciparum protein-protein interactions is limited by poor expression of P. falciparum genes in yeast and lack of easily implemented assays to confirm the results. We report here two methods to create gene fragments - random fragmentation by partial DNAse I digestion and generation of densely overlapping fragments by PCR - that enable most portions of P. falciparum genes to be expressed and screened in the yeast two-hybrid assay. The PCR-based method is less technically challenging and facilitates fine-scale mapping of protein interaction domains. Both approaches revealed a putative interaction between PfMyb2 (PF10_0327) and PFC0365w. We developed new plasmids to express the proteins in wheat germ extracts and confirmed the interaction in both the split-luciferase assay and in co-purification experiments with glutathione-S-transferase and HA-tagged proteins. The combination of improved yeast two-hybrid screening approaches and convenient systems to validate interactions enhances the utility of yeast two-hybrid assays for P. falciparum.

  15. Resistance of Plasmodium falciparum malaria to chloroquine is widespread in eastern Afghanistan.

    PubMed

    Rab, M A; Freeman, T W; Durrani, N; de Poerck, D; Rowland, M W

    2001-01-01

    After two decades of war and conflict in Afghanistan, the public-health system is in disarray and malaria has re-emerged as a major disease, with Plasmodium falciparum malaria becoming increasingly common. The limited healthcare services that are available are mainly delivered by non-governmental organizations in collaboration with the Ministry of Health. Although chloroquine (CQ) remains the official first-line treatment against P. falciparum malaria, there is little information on the severity or distribution of resistance to this drug in Afghanistan. In-vivo surveys, co-ordinated by the Malaria Reference Centre in Jalalabad, were therefore performed to determine the frequency and grades of CQ resistance in the three eastern provinces of Kunar, Nangarhar and Laghman. Of the 142 cases enrolled in the study, only 47 (33%) were sensitive. Most of the cases (55%) showed RI resistance but RII/RIII resistance was not uncommon (11%). The prevalence of resistance appeared similar in children and adults, in males and females, and in each of the three provinces investigated. Gametocyte carriage post-treatment was elevated in the resistant cases. As in neighbouring Pakistan, the resurgence of P. falciparum in Afghanistan is probably associated with the transmission and spread of chloroquine-resistant strains. The first-line therapy used against P. falciparum malaria must be changed in order to reverse this trend.

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

    PubMed Central

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

    2016-01-01

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

  17. Global response of Plasmodium falciparum to hyperoxia: a combined transcriptomic and proteomic approach

    PubMed Central

    2011-01-01

    Background Over its life cycle, the Plasmodium falciparum parasite is exposed to different environmental conditions, particularly to variations in O2 pressure. For example, the parasite circulates in human venous blood at 5% O2 pressure and in arterial blood, particularly in the lungs, at 13% O2 pressure. Moreover, the parasite is exposed to 21% O2 levels in the salivary glands of mosquitoes. Methods To study the metabolic adaptation of P. falciparum to different oxygen pressures during the intraerythrocytic cycle, a combined approach using transcriptomic and proteomic techniques was undertaken. Results Even though hyperoxia lengthens the parasitic cycle, significant transcriptional changes were detected in hyperoxic conditions in the late-ring stage. Using PS 6.0™ software (Ariadne Genomics) for microarray analysis, this study demonstrate up-expression of genes involved in antioxidant systems and down-expression of genes involved in the digestive vacuole metabolism and the glycolysis in favour of mitochondrial respiration. Proteomic analysis revealed increased levels of heat shock proteins, and decreased levels of glycolytic enzymes. Some of this regulation reflected post-transcriptional modifications during the hyperoxia response. Conclusions These results seem to indicate that hyperoxia activates antioxidant defence systems in parasites to preserve the integrity of its cellular structures. Moreover, environmental constraints seem to induce an energetic metabolism adaptation of P. falciparum. This study provides a better understanding of the adaptive capabilities of P. falciparum to environmental changes and may lead to the development of novel therapeutic targets. PMID:21223545

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

    PubMed

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

    2006-10-01

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

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

    PubMed Central

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

    2006-01-01

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

  20. The hydration state of human red blood cells and their susceptibility to invasion by Plasmodium falciparum.

    PubMed

    Tiffert, Teresa; Lew, Virgilio L; Ginsburg, Hagai; Krugliak, Miriam; Croisille, Laure; Mohandas, Narla

    2005-06-15

    In most inherited red blood cell (RBC) disorders with high gene frequencies in malaria-endemic regions, the distribution of RBC hydration states is much wider than normal. The relationship between the hydration state of circulating RBCs and protection against severe falciparum malaria remains unexplored. The present investigation was prompted by a casual observation suggesting that falciparum merozoites were unable to invade isotonically dehydrated normal RBCs. We designed an experimental model to induce uniform and stable isotonic volume changes in RBC populations from healthy donors by increasing or decreasing their KCl contents through a reversible K(+) permeabilization pulse. Swollen and mildly dehydrated RBCs were able to sustain Plasmodium falciparum cultures with similar efficiency to untreated RBCs. However, parasite invasion and growth were progressively reduced in dehydrated RBCs. In a parallel study, P falciparum invasion was investigated in density-fractionated RBCs from healthy subjects and from individuals with inherited RBC abnormalities affecting primarily hemoglobin (Hb) or the RBC membrane (thalassemias, hereditary ovalocytosis, xerocytosis, Hb CC, and Hb CS). Invasion was invariably reduced in the dense cell fractions in all conditions. These results suggest that the presence of dense RBCs is a protective factor, additional to any other protection mechanism prevailing in each of the different pathologies.

  1. The hydration state of human red blood cells and their susceptibility to invasion by Plasmodium falciparum

    PubMed Central

    Tiffert, Teresa; Lew, Virgilio L.; Ginsburg, Hagai; Krugliak, Miriam; Croisille, Laure; Mohandas, Narla

    2005-01-01

    In most inherited red blood cell (RBC) disorders with high gene frequencies in malaria-endemic regions, the distribution of RBC hydration states is much wider than normal. The relationship between the hydration state of circulating RBCs and protection against severe falciparum malaria remains unexplored. The present investigation was prompted by a casual observation suggesting that falciparum merozoites were unable to invade isotonically dehydrated normal RBCs. We designed an experimental model to induce uniform and stable isotonic volume changes in RBC populations from healthy donors by increasing or decreasing their KCl contents through a reversible K+ permeabilization pulse. Swollen and mildly dehydrated RBCs were able to sustain Plasmodium falciparum cultures with similar efficiency to untreated RBCs. However, parasite invasion and growth were progressively reduced in dehydrated RBCs. In a parallel study, P falciparum invasion was investigated in density-fractionated RBCs from healthy subjects and from individuals with inherited RBC abnormalities affecting primarily hemoglobin (Hb) or the RBC membrane (thalassemias, hereditary ovalocytosis, xerocytosis, Hb CC, and Hb CS). Invasion was invariably reduced in the dense cell fractions in all conditions. These results suggest that the presence of dense RBCs is a protective factor, additional to any other protection mechanism prevailing in each of the different pathologies. (Blood. 2005; 105:4853-4860) PMID:15728121

  2. Efficacy of monthly tafenoquine for prophylaxis of Plasmodium vivax and multidrug-resistant P. falciparum malaria.

    PubMed

    Walsh, Douglas S; Eamsila, Chirapa; Sasiprapha, Theerayuth; Sangkharomya, Suebpong; Khaewsathien, Pradith; Supakalin, Panpaka; Tang, Douglas B; Jarasrumgsichol, Phongsak; Cherdchu, Chainarong; Edstein, Michael D; Rieckmann, Karl H; Brewer, Thomas G

    2004-10-15

    We assessed monthly doses of tafenoquine for preventing Plasmodium vivax and multidrug-resistant P. falciparum malaria. In a randomized, double-blind, placebo-controlled study, 205 Thai soldiers received either a loading dose of tafenoquine 400 mg (base) daily for 3 days, followed by single monthly 400-mg doses (n = 104), or placebo (n = 101), for up to 5 consecutive months. In volunteers completing follow-up (96 tafenoquine and 91 placebo recipients), there were 22 P. vivax, 8 P. falciparum, and 1 mixed infection. All infections except 1 P. vivax occurred in placebo recipients, giving tafenoquine a protective efficacy of 97% for all malaria (95% confidence interval [CI], 82%-99%), 96% for P. vivax malaria (95% CI, 76%-99%), and 100% for P. falciparum malaria (95% CI, 60%-100%). Monthly tafenoquine was safe, well tolerated, and highly effective in preventing P. vivax and multidrug-resistant P. falciparum malaria in Thai soldiers during 6 months of prophylaxis. Copyright 2004 Infectious Diseases Society of America

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

    PubMed

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

    1986-09-04

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

  4. Survey of in vivo sensitivity to chloroquine by Plasmodium falciparum and P. vivax in Lombok, Indonesia.

    PubMed

    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.

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

    PubMed

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

    2006-08-01

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

  6. [Resistance of Plasmodium falciparum to 3 antimalarials in Turbo (Antioquia, Colombia), 1998].

    PubMed

    Blair, S; Lacharme, L L; Fonseca, J C; Tobón, A

    2001-01-01

    In 1998 we determined in vivo and in vitro the frequency and the degree of resistance of Plasmodium falciparum to the three antimalarials (chloroquine, amodiaquine, and sulfadoxine/pyrimethamine) most utilized in the municipality of Turbo (in the area of Urabá, Antioquia, Colombia), in a sample representative of the population with malaria. We carried out clinical and parasitological analyses over a 14-day period using the standard test recommended by the World Health Organization. In vivo, P. falciparum showed resistance to chloroquine, amodiaquine, and sulfadoxine/pyrimethamine, with a frequency of 97%, 7%, and 13%, respectively. In vitro, the corresponding figures were 21%, 23%, and 9%, respectively. For chloroquine the level of agreement between the in vivo and in vitro results was 23%.

  7. Blood Stage Plasmodium falciparum Exhibits Biological Responses to Direct Current Electric Fields

    PubMed Central

    Coronado, Lorena M.; Montealegre, Stephania; Chaverra, Zumara; Mojica, Luis; Espinosa, Carlos; Almanza, Alejandro; Correa, Ricardo; Stoute, José A.; Gittens, Rolando A.

    2016-01-01

    The development of resistance to insecticides by the vector of malaria and the increasingly faster appearance of resistance to antimalarial drugs by the parasite can dangerously hamper efforts to control and eradicate the disease. Alternative ways to treat this disease are urgently needed. Here we evaluate the in vitro effect of direct current (DC) capacitive coupling electrical stimulation on the biology and viability of Plasmodium falciparum. We designed a system that exposes infected erythrocytes to different capacitively coupled electric fields in order to evaluate their effect on P. falciparum. The effect on growth of the parasite, replication of DNA, mitochondrial membrane potential and level of reactive oxygen species after exposure to electric fields demonstrate that the parasite is biologically able to respond to stimuli from DC electric fields involving calcium signaling pathways. PMID:27537497

  8. Complement Activation Correlates With Disease Severity and Contributes to Cytokine Responses in Plasmodium falciparum Malaria.

    PubMed

    Berg, Aase; Otterdal, Kari; Patel, Sam; Gonca, Miguel; David, Catarina; Dalen, Ingvild; Nymo, Stig; Nilsson, Margareta; Nordling, Sofia; Magnusson, Peetra U; Ueland, Thor; Prato, Mauro; Giribaldi, Giuliana; Mollnes, Tom Eirik; Aukrust, Pål; Langeland, Nina; Nilsson, Per H

    2015-12-01

    The impact of complement activation and its possible relation to cytokine responses during malaria pathology was investigated in plasma samples from patients with confirmed Plasmodium falciparum malaria and in human whole-blood specimens stimulated with malaria-relevant agents ex vivo. Complement was significantly activated in the malaria cohort, compared with healthy controls, and was positively correlated with disease severity and with certain cytokines, in particular interleukin 8 (IL-8)/CXCL8. This was confirmed in ex vivo-stimulated blood specimens, in which complement inhibition significantly reduced IL-8/CXCL8 release. P. falciparum malaria is associated with systemic complement activation and complement-dependent release of inflammatory cytokines, of which IL-8/CXCL8 is particularly prominent. © 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.

  9. TRALI Syndrome During the Treatment of a Plasmodium falciparum Malaria Case.

    PubMed

    Çaşkurlu, Hülya; Nurmuhammedov, Rahman; Htway, Zarni

    2016-12-01

    Malaria, which is one of the three most important infectious diseases globally, is endemic in many areas of the world. Plasmodium falciparum is not endemic to Turkey but can be seen after travel to epidemic countries. Transfusion-related acute lung injury (TRALI) syndrome is a rare disease, which may develop following the transfusion of all types of blood products, including plasma. Here we describe a case of TRALI syndrome in a 29-year-old male, who presented with fever after 15 days of returning from a business trip to Burkina Faso. It developed immediately after the infusion of fresh frozen plasma during the treatment of P. falciparum malaria. The patient's condition improved on respiratory support treatment in the intensive care unit for 48 hours without the need of mechanical ventilation. This case indicated that TRALI syndrome has to be considered in the differential diagnosis as an emerging acute lung disease during the treatment of malaria.

  10. Prevalence of multiple drug-resistant Plasmodium falciparum malaria cases in Northeast India.

    PubMed

    Sharma, Jitendra; Khan, Siraj Ahmed; Soni, Monika; Dutta, Prafulla

    2017-01-01

    Two numbers of Plasmodium falciparum field isolates from Gossingpara, Runikhata area in Chirang district of Assam had shown multiple mutations in Pfcrt-dhfr-dhps gene (up to seven mutations: One mutation in Pfcrt gene, three mutations in Pfdhfr gene and three mutations in Pfdhps gene). Similarly, two cases in Bat camp, Miao area under Changlang district of Arunachal Pradesh had shown a total of eight mutations, of which one mutation in Pfcrt gene, three mutations in Pfdhfr gene, three mutations in Pfdhps gene and one mutation in PfATPase6 gene. One case in 3 Miles, Miao area of Changlang district has shown mutations in Pfcrt(one mutation), Pfdhfr(four mutations) and Pfdhps(three mutations) gene. These results indicated that there is an existence of multiple mutant P. falciparum malaria cases in northeastern region of India.

  11. Genetic Investigation of Tricarboxylic Acid Metabolism During the Plasmodium falciparum Lifecycle

    PubMed Central

    Ke, Hangjun; Lewis, Ian A.; Morrisey, Joanne M.; McLean, Kyle J.; Ganesan, Suresh M.; Painter, Heather J.; Mather, Michael W.; Jacobs-Lorena, Marcelo; Llinás, Manuel; Vaidya, Akhil B.

    2015-01-01

    SUMMARY New antimalarial drugs are urgently needed to control drug resistant forms of the malaria parasite, Plasmodium falciparum. Mitochondrial electron transport is the target of both existing and new antimalarials. Herein, we describe 11 genetic knockout (KO) lines that delete six of the eight mitochondrial tricarboxylic acid (TCA) cycle enzymes. Although all TCA KOs grew normally in asexual blood stages, these metabolic deficiencies halted lifecycle progression in later stages. Specifically, aconitase KO parasites arrested as late gametocytes, whereas α-ketoglutarate dehydrogenase deficient parasites failed to develop oocysts in the mosquitoes. Mass spectrometry analysis of 13C isotope-labeled TCA mutant parasites showed that P. falciparum has significant flexibility in TCA metabolism. This flexibility manifested itself through changes in pathway fluxes and through altered exchange of substrates between cytosolic and mitochondrial pools. Our findings suggest that mitochondrial metabolic plasticity is essential for parasite development. PMID:25843709

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

    PubMed

    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. K13-Propeller Polymorphisms in Plasmodium falciparum Parasites From Sub-Saharan Africa

    PubMed Central

    Kamau, Edwin; Campino, Susana; Amenga-Etego, Lucas; Drury, Eleanor; Ishengoma, Deus; Johnson, Kimberly; Mumba, Dieudonne; Kekre, Mihir; Yavo, William; Mead, Daniel; Bouyou-Akotet, Marielle; Apinjoh, Tobias; Golassa, Lemu; Randrianarivelojosia, Milijaona; Andagalu, Ben; Maiga-Ascofare, Oumou; Amambua-Ngwa, Alfred; Tindana, Paulina; Ghansah, Anita; MacInnis, Bronwyn; Kwiatkowski, Dominic; Djimde, Abdoulaye A.

    2015-01-01

    Mutations in the Plasmodium falciparum K13-propeller domain have recently been shown to be important determinants of artemisinin resistance in Southeast Asia. This study investigated the prevalence of K13-propeller polymorphisms across sub-Saharan Africa. A total of 1212 P. falciparum samples collected from 12 countries were sequenced. None of the K13-propeller mutations previously reported in Southeast Asia were found, but 22 unique mutations were detected, of which 7 were nonsynonymous. Allele frequencies ranged between 1% and 3%. Three mutations were observed in >1 country, and the A578S was present in parasites from 5 countries. This study provides the baseline prevalence of K13-propeller mutations in sub-Saharan Africa. PMID:25367300

  14. Analysis of the genetic diversity of the Plasmodium falciparum multidrug resistance gene 5' upstream region.

    PubMed

    Myrick, Alissa; Sarr, Ousmane; Dieng, Therese; Ndir, Omar; Mboup, Souleymane; Wirth, Dyann F

    2005-02-01

    Recent findings indicating a low level of polymorphism in the Plasmodium falciparum genome have led to the hypothesis that existent polymorphisms are likely to have functional significance. We tested this hypothesis by developing a map of the polymorphism in the P. falciparum multidrug resistance 1 (pfmdr1) gene 5' upstream region and assaying its correlation with drug resistance in a sample of field isolates from Dakar, Senegal. A comparison of six geographically diverse laboratory strains showed that the 1.94-kb 5'-untranslated region is highly monomorphic, with a total of four unique single nucleotide polymorphisms (SNPs) being identified. All of the mutations were localized to a 462-basepair region proximal to the transcription start point. Analysis of this region in field isolates shows the prevalence of one SNP throughout the entire population of parasites, irrespective of drug resistance status. The SNP frequency of the pfmdr1 upstream region is lower than that found in the noncoding region of other genes.

  15. Inhibition of an Erythrocyte Tyrosine Kinase with Imatinib Prevents Plasmodium falciparum Egress and Terminates Parasitemia

    PubMed Central

    Kesely, Kristina R.; Pantaleo, Antonella; Turrini, Francesco M.; Olupot-Olupot, Peter

    2016-01-01

    With half of the world’s population at risk for malaria infection and with drug resistance on the rise, the search for mutation-resistant therapies has intensified. We report here a therapy for Plasmodium falciparum malaria that acts by inhibiting the phosphorylation of erythrocyte membrane band 3 by an erythrocyte tyrosine kinase. Because tyrosine phosphorylation of band 3 causes a destabilization of the erythrocyte membrane required for parasite egress, inhibition of the erythrocyte tyrosine kinase leads to parasite entrapment and termination of the infection. Moreover, because one of the kinase inhibitors to demonstrate antimalarial activity is imatinib, i.e. an FDA-approved drug authorized for use in children, translation of the therapy into the clinic will be facilitated. At a time when drug resistant strains of P. falciparum are emerging, a strategy that targets a host enzyme that cannot be mutated by the parasite should constitute a therapeutic mechanism that will retard evolution of resistance. PMID:27768734

  16. The mechanism of erythrocyte invasion by the malarial parasite, Plasmodium falciparum.

    PubMed

    Farrow, Rachel E; Green, Judith; Katsimitsoulia, Zoe; Taylor, William R; Holder, Anthony A; Molloy, Justin E

    2011-12-01

    Plasmodium falciparum is the most virulent causative agent of malaria in man accounting for 80% of all malarial infections and 90% of the one million annual deaths attributed to malaria. P. falciparum is a unicellular, Apicomplexan parasite, that spends part of its lifecycle in the mosquito and part in man and it has evolved a special form of motility that enables it to burrow into animal cells, a process termed "host cell invasion". The acute, life threatening, phase of malarial infection arises when the merozoite form of the parasite undergoes multiple cycles of red blood cell invasion and rapid proliferation. Here, we discuss the molecular machinery that enables malarial parasites to invade red blood cells and we focus particularly on the ATP-driven acto-myosin motor that powers invasion.

  17. Jacaranone-derived glucosidic esters from Jacaranda glabra and their activity against Plasmodium falciparum.

    PubMed

    Gachet, M Salomé; Kunert, Olaf; Kaiser, Marcel; Brun, Reto; Muñoz, Ricardo A; Bauer, Rudolf; Schühly, Wolfgang

    2010-04-23

    In a survey of plants from Ecuador with antiprotozoal activity, Jacaranda glabra was found to show promising activity against the Plasmodium falciparum K1 strain. Subsequently, activity-guided isolation of the dichloromethane extract from the leaves of J. glabra afforded four new phenylethanoid glucosides containing jacaranone-type moieties (1-4), named jacaglabrosides A-D. Their chemical structures were identified using NMR spectroscopy and MS techniques. The compounds were found to be active in vitro against the P. falciparum K1 strain (IC(50) 1, 1.02; 2, 0.56; 3, 0.56; and 4, 0.55 microg/mL) and generally possessed a low cytotoxicity toward L-6 cells, with the exception of compound 1 (IC(50) 1, 8.3; 2, >90; 3, 87; and 4, 85 microg/mL).

  18. A Method for Rapid Genetic Integration into Plasmodium falciparum Utilizing Mycobacteriophage Bxb1 Integrase

    PubMed Central

    Adjalley, Sophie H.; Lee, Marcus C.S.; Fidock, David A.

    2011-01-01

    Genetic manipulation of the human malaria parasite Plasmodium falciparum has presented substantial challenges for research efforts aimed at better understanding the complex biology of this highly virulent organism. The development of methods to perform gene disruption, allelic replacement or transgene expression has provided important insights into the function of parasite genes. However, genomic integration studies have been hindered by low transfection and recombination efficiencies, and are complicated by the propensity of this parasite to maintain episomal replicating plasmids. We have developed a fast and efficient site-specific system of integrative recombination into the P. falciparum genome, which is catalyzed by the mycobacteriophage Bxb1 serine integrase. This system has the advantage of providing greater genetic and phenotypic homogeneity within transgenic lines as compared to earlier methods based on episomal replication of plasmids. Herein, we present this methodology. PMID:20676977

  19. Plasmodium falciparum: assessment of in vitro growth by (/sup 3/H)hypoxanthine incorporation

    SciTech Connect

    Chulay, J.D.; Haynes, J.D.; Diggs, C.L.

    1983-02-01

    To evaluate rapidly Plasmodium falciparum growth in Vitro, (/sup 3/H)hypoxanthine was added to parasite microcultures and radioisotope incorporation was measured. When culture parameters were carefully controlled, (/sup 3/H)hypoxanthine incorporation was proportional to the number of parasitized erythrocytes present. Factors affecting (/sup 3/H)hypoxanthine incorporation included initial parasitemia, duration of culture, duration of radioisotope pulse, parasite stage, concentration of uninfected erythrocytes, the use of serum or plasma to supplement growth, and the concentration of a variety of purines in the culture medium. The method described can be used to measure inhibition of P. falciparum growth by immune serum and has previously been used to study antimalarial drug activity in vitro.

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

    PubMed Central

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

    2005-01-01

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

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

    PubMed Central

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

    2013-01-01

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

  2. Plasmodium falciparum kelch 13: a potential molecular marker for tackling artemisinin-resistant malaria parasites.

    PubMed

    Mita, Toshihiro; Tachibana, Shin-Ichiro; Hashimoto, Muneaki; Hirai, Makoto

    2016-01-01

    Although artemisinin combination therapies have been deployed as a first-line treatment for uncomplicated malaria in almost all endemic countries, artemisinin-resistant parasites have emerged and have gradually spread across the Greater Mekong subregions. There is growing concern that the resistant parasites may migrate to or emerge indigenously in sub-Saharan Africa, which might provoke a global increase in malaria-associated morbidity and mortality. Therefore, development of molecular markers that enable identification of artemisinin resistance with high sensitivity is urgently required to combat this issue. In 2014, a potential artemisinin-resistance responsible gene, Plasmodium falciparum kelch13, was discovered. Here, we review the genetic features of P. falciparum kelch13 and discuss its related resistant mechanisms and potential as a molecular marker.

  3. Surveillance of artemisinin resistance in Plasmodium falciparum in India using the kelch13 molecular marker.

    PubMed

    Mishra, Neelima; Prajapati, Surendra Kumar; Kaitholia, Kamlesh; Bharti, Ram Suresh; Srivastava, Bina; Phookan, Sobhan; Anvikar, Anupkumar R; Dev, Vas; Sonal, Gagan Singh; Dhariwal, Akshay Chandra; White, Nicholas J; Valecha, Neena

    2015-05-01

    Malaria treatment in Southeast Asia is threatened with the emergence of artemisinin-resistant Plasmodium falciparum. Genome association studies have strongly linked a locus on P. falciparum chromosome 13 to artemisinin resistance, and recently, mutations in the kelch13 propeller region (Pfk-13) were strongly linked to resistance. To date, this information has not been shown in Indian samples. Pfk-13 mutations were assessed in samples from efficacy studies of artemisinin combination treatments in India. Samples were PCR amplified and sequenced from codon 427 to 727. Out of 384 samples, nonsynonymous mutations in the propeller region were found in four patients from the northeastern states, but their presence did not correlate with ACT treatment failures. This is the first report of Pfk-13 point mutations from India. Further phenotyping and genotyping studies are required to assess the status of artemisinin resistance in this region.

  4. [In vitro cultivation of fields isolates of Plasmodium falciparum in Mali].

    PubMed

    Djimde, A A; Kirkman, L; Kassambara, L; Diallo, M; Plowe, C V; Wellems, T E; Doumbo, O K

    2007-02-01

    Malaria immunology, molecular biology and pathogenicity studies often require the adaptation of Plasmodium falciparum field isolates to continuous in vitro cultivation. For this purpose we have established propagation protocols of asexual erythrocytic stages of P. falciparum samples from malaria patients or asymptomatic carriers in Mali. The parasites were grown in standard culture medium supplemented by human serum and in a culture medium without human serum but supplemented by AlbuMax 1. The candle jar environment and tissue culture flasks gassed with 5% CO2, 5% O2 and 90% N2 obtained from a portable gas mixer were used. Protocols for parasite cultivation in a resource-poor setting were developed. These protocols were successfully applied to fresh isolates in Mali as well as to blood samples frozen in liquid nitrogen and shipped to a laboratory in U.S.A.

  5. Blood Stage Plasmodium falciparum Exhibits Biological Responses to Direct Current Electric Fields.

    PubMed

    Coronado, Lorena M; Montealegre, Stephania; Chaverra, Zumara; Mojica, Luis; Espinosa, Carlos; Almanza, Alejandro; Correa, Ricardo; Stoute, José A; Gittens, Rolando A; Spadafora, Carmenza

    2016-01-01

    The development of resistance to insecticides by the vector of malaria and the increasingly faster appearance of resistance to antimalarial drugs by the parasite can dangerously hamper efforts to control and eradicate the disease. Alternative ways to treat this disease are urgently needed. Here we evaluate the in vitro effect of direct current (DC) capacitive coupling electrical stimulation on the biology and viability of Plasmodium falciparum. We designed a system that exposes infected erythrocytes to different capacitively coupled electric fields in order to evaluate their effect on P. falciparum. The effect on growth of the parasite, replication of DNA, mitochondrial membrane potential and level of reactive oxygen species after exposure to electric fields demonstrate that the parasite is biologically able to respond to stimuli from DC electric fields involving calcium signaling pathways.

  6. Comparative testing of monoclonal antibodies against Plasmodium falciparum sporozoites for ELISA development*

    PubMed Central

    Wirtz, R. A.; Zavala, F.; Charoenvit, Y.; Campbell, G. H.; Burkot, T. R.; Schneider, I.; Esser, K. M.; Beaudoin, R. L.; Andre, R. G.

    1987-01-01

    Ten monoclonal antibodies developed against Plasmodium falciparum sporozoites at four institutions were evaluated for use in an enzyme-linked immunosorbent assay (ELISA). Four of the antibodies were eliminated because of their low sensitivity or requirement for high concentrations of capture antibody, while an additional four were rejected because they exhibited cross-reactivity with P. berghei sporozoites. Of the two remaining monoclonal antibodies, that designated 2A10 had the highest sensitivity, a requirement for lower concentrations of capture antibody, and had been tested successfully against sporozoites from a wider range of geographical areas than the others. Use of this monoclonal antibody in a standardized ELISA method gave a test ten times more sensitive than previously reported for P. falciparum sporozoites and its detection limit was less than 100 sporozoites per mosquito. PMID:3555879

  7. NF135.C10: A New Plasmodium falciparum Clone for Controlled Human Malaria Infections

    PubMed Central

    Teirlinck, Anne C.; Roestenberg, Meta; van de Vegte-Bolmer, Marga; Scholzen, Anja; Heinrichs, Moniek J. L.; Siebelink-Stoter, Rianne; Graumans, Wouter; van Gemert, Geert-Jan; Teelen, Karina; Vos, Martijn W.; Nganou-Makamdop, Krystelle; Borrmann, Steffen; Rozier, Yolanda P. A.; Erkens, Marianne A. A.; Luty, Adrian J. F.; Hermsen, Cornelus C.; Sim, B. Kim Lee; van Lieshout, Lisette; Hoffman, Stephen L.; Visser, Leo G.; Sauerwein, Robert W.

    2013-01-01

    We established a new field clone of Plasmodium falciparum for use in controlled human malaria infections and vaccine studies to complement the current small portfolio of P. falciparum strains, primarily based on NF54. The Cambodian clone NF135.C10 consistently produced gametocytes and generated substantial numbers of sporozoites in Anopheles mosquitoes and diverged from NF54 parasites by genetic markers. In a controlled human malaria infection trial, 3 of 5 volunteers challenged by mosquitoes infected with NF135.C10 and 4 of 5 challenged with NF54 developed parasitemia as detected with microscopy. The 2 strains induced similar clinical signs and symptoms as well as cellular immunological responses. Clinical Trials Registration NCT01002833. PMID:23186785

  8. Inhibition of an Erythrocyte Tyrosine Kinase with Imatinib Prevents Plasmodium falciparum Egress and Terminates Parasitemia.

    PubMed

    Kesely, Kristina R; Pantaleo, Antonella; Turrini, Francesco M; Olupot-Olupot, Peter; Low, Philip S

    2016-01-01

    With half of the world's population at risk for malaria infection and with drug resistance on the rise, the search for mutation-resistant therapies has intensified. We report here a therapy for Plasmodium falciparum malaria that acts by inhibiting the phosphorylation of erythrocyte membrane band 3 by an erythrocyte tyrosine kinase. Because tyrosine phosphorylation of band 3 causes a destabilization of the erythrocyte membrane required for parasite egress, inhibition of the erythrocyte tyrosine kinase leads to parasite entrapment and termination of the infection. Moreover, because one of the kinase inhibitors to demonstrate antimalarial activity is imatinib, i.e. an FDA-approved drug authorized for use in children, translation of the therapy into the clinic will be facilitated. At a time when drug resistant strains of P. falciparum are emerging, a strategy that targets a host enzyme that cannot be mutated by the parasite should constitute a therapeutic mechanism that will retard evolution of resistance.

  9. In silico screening for Plasmodium falciparum enoyl-ACP reductase inhibitors

    NASA Astrophysics Data System (ADS)

    Lindert, Steffen; Tallorin, Lorillee; Nguyen, Quynh G.; Burkart, Michael D.; McCammon, J. Andrew

    2015-01-01

    The need for novel therapeutics against Plasmodium falciparum is urgent due to recent emergence of multi-drug resistant malaria parasites. Since fatty acids are essential for both the liver and blood stages of the malarial parasite, targeting fatty acid biosynthesis is a promising strategy for combatting P. falciparum. We present a combined computational and experimental study to identify novel inhibitors of enoyl-acyl carrier protein reductase ( PfENR) in the fatty acid biosynthesis pathway. A small-molecule database from ChemBridge was docked into three distinct PfENR crystal structures that provide multiple receptor conformations. Two different docking algorithms were used to generate a consensus score in order to rank possible small molecule hits. Our studies led to the identification of five low-micromolar pyrimidine dione inhibitors of PfENR.

  10. Plasmodium falciparum: induction of resistance to mefloquine in cloned strains by continuous drug exposure in vitro.

    PubMed

    Oduola, A M; Milhous, W K; Weatherly, N F; Bowdre, J H; Desjardins, R E

    1988-12-01

    A genetically homogeneous population of Plasmodium falciparum prepared by a single erythrocyte micromanipulation technique was used to produce lines of P. falciparum resistant to mefloquine hydrochloride in vitro. Parasites were maintained in a culture medium containing gradually increased concentrations of mefloquine hydrochloride (CMP-mef) starting with 2 ng/ml. One of the mefloquine-resistant culture lines (W2-mef) was obtained after 96 weeks of continuous culture in CMP-mef, the last 4 weeks in medium containing 40 ng/ml of mefloquine hydrochloride. The W2-mef was four to six times more resistant to mefloquine than was the parent clone W2. Means of multiple determinations of 50% inhibitory concentrations (IC-50) of mefloquine hydrochloride against W2-mef and clone W2 were 20.39 +/- 5.08 ng/ml and 4.50 +/- 1.94 ng/ml, respectively.

  11. A genomic glimpse of aminoacyl-tRNA synthetases in malaria parasite Plasmodium falciparum

    PubMed Central

    2009-01-01

    Background Plasmodium parasites are causative agents of malaria which affects >500 million people and claims ~2 million lives annually. The completion of Plasmodium genome sequencing and availability of PlasmoDB database has provided a platform for systematic study of parasite genome. Aminoacyl-tRNA synthetases (aaRSs) are pivotal enzymes for protein translation and other vital cellular processes. We report an extensive analysis of the Plasmodium falciparum genome to identify and classify aaRSs in this organism. Results Using various computational and bioinformatics tools, we have identified 37 aaRSs in P. falciparum. Our key observations are: (i) fraction of proteome dedicated to aaRSs in P. falciparum is very high compared to many other organisms; (ii) 23 out of 37 Pf-aaRS sequences contain signal peptides possibly directing them to different cellular organelles; (iii) expression profiles of Pf-aaRSs vary considerably at various life cycle stages of the parasite; (iv) several PfaaRSs posses very unusual domain architectures; (v) phylogenetic analyses reveal evolutionary relatedness of several parasite aaRSs to bacterial and plants aaRSs; (vi) three dimensional structural modelling has provided insights which could be exploited in inhibitor discovery against parasite aaRSs. Conclusion We have identified 37 Pf-aaRSs based on our bioinformatics analysis. Our data reveal several unique attributes in this protein family. We have annotated all 37 Pf-aaRSs based on predicted localization, phylogenetics, domain architectures and their overall protein expression profiles. The sets of distinct features elaborated in this work will provide a platform for experimental dissection of this family of enzymes, possibly for the discovery of novel drugs against malaria. PMID:20042123

  12. Genome-wide identification of novel intergenic enhancer-like elements: implications in the regulation of transcription in Plasmodium falciparum.

    PubMed

    Ubhe, Suyog; Rawat, Mukul; Verma, Srikant; Anamika, Krishanpal; Karmodiya, Krishanpal

    2017-08-23

    The molecular mechanisms of transcriptional regulation are poorly understood in Plasmodium falciparum. In addition, most of the genes in Plasmodium falciparum are transcriptionally poised and only a handful of cis-regulatory elements are known to operate in transcriptional regulation. Here, we employed an epigenetic signature based approach to identify significance of previously uncharacterised intergenic regions enriched with histone modification marks leading to discovery of enhancer-like elements. We found that enhancer-like elements are significantly enriched with H3K4me1, generate unique non-coding bi-directional RNAs and majority of them can function as cis-regulators. Furthermore, functional enhancer reporter assay demonstrates that the enhancer-like elements regulate transcription of target genes in Plasmodium falciparum. Our study also suggests that the Plasmodium genome segregates functionally related genes into discrete housekeeping and pathogenicity/virulence clusters, presumably for robust transcriptional control of virulence/pathogenicity genes. This report contributes to the understanding of parasite regulatory genomics by identification of enhancer-like elements, defining their epigenetic and transcriptional features and provides a resource of functional cis-regulatory elements that may give insights into the virulence/pathogenicity of Plasmodium falciparum.

  13. Homopolymer tract organization in the human malarial parasite Plasmodium falciparum and related Apicomplexan parasites.

    PubMed

    Russell, Karen; Cheng, Chia-Ho; Bizzaro, Jeffrey W; Ponts, Nadia; Emes, Richard D; Le Roch, Karine; Marx, Kenneth A; Horrocks, Paul

    2014-10-03

    Homopolymeric tracts, particularly poly dA.dT, are enriched within the intergenic sequences of eukaryotic genomes where they appear to act as intrinsic regulators of nucleosome positioning. A previous study of the incomplete genome of the human malarial parasite Plasmodium falciparum reports a higher than expected enrichment of poly dA.dT tracts, far above that anticipated even in this highly AT rich genome. Here we report an analysis of the relative frequency, length and spatial arrangement of homopolymer tracts for the complete P. falciparum genome, extending this analysis to twelve additional genomes of Apicomplexan parasites important to human and animal health. In addition, using nucleosome-positioning data available for P. falciparum, we explore the correlation of poly dA.dT tracts with nucleosome-positioning data over key expression landmarks within intergenic regions. We describe three apparent lineage-specific patterns of homopolymeric tract organization within the intergenic regions of these Apicomplexan parasites. Moreover, a striking pattern of enrichment of overly long poly dA.dT tracts in the intergenic regions of Plasmodium spp. uniquely extends into protein coding sequences. There is a conserved spatial arrangement of poly dA.dT immediately flanking open reading frames and over predicted core promoter sites. These key landmarks are all relatively depleted in nucleosomes in P. falciparum, as would be expected for poly dA.dT acting as nucleosome exclusion sequences. Previous comparative studies of homopolymer tract organization emphasize evolutionary diversity; this is the first report of such an analysis within a single phylum. Our data provide insights into the evolution of homopolymeric tracts and the selective pressures at play in their maintenance and expansion.

  14. A replicating adenovirus capsid display recombinant elicits antibodies against Plasmodium falciparum sporozoites in Aotus nancymaae monkeys.

    PubMed

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

    2015-01-01

    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 antibodies in mice. Human adenoviruses do not replicate in mice. Therefore, to examine immunogenicity in a system in which, as in humans, the recombinant replicates, we constructed a similar recombinant in an adenovirus mutant that replicates in monkey cells and immunized four Aotus nancymaae monkeys. The recombinant replicated in the monkeys after intratracheal instillation, the first demonstration of replication of human adenoviruses in New World monkeys. Immunization elicited antibodies both to the Plasmodium epitope and the Ad5 vector. Antibodies from all four monkeys recognized CSP on intact parasites, and plasma from one monkey neutralized sporozoites in vitro and conferred partial protection against P. falciparum sporozoite infection after passive transfer to mice. Prior enteric inoculation of two animals with antigenically wild-type adenovirus primed a response to the subsequent intratracheal inoculation, suggesting a route to optimizing performance. A vaccine is not yet available against P. falciparum, which induces the deadliest form of malaria and kills approximately one million children each year. The live capsid display recombinant described here may constitute an early step in a critically needed novel approach to malaria immunization.

  15. Plasmodium falciparum Malaria: Band 3 as a Possible Receptor during Invasion of Human Erythrocytes

    NASA Astrophysics Data System (ADS)

    Okoye, Vincent C. N.; Bennett, Vann

    1985-01-01

    Human erythrocyte band 3, a major membrane-spanning protein, was purified and incorporated into liposomes. These liposomes, at nanomolar concentrations of protein, inhibited invasion of human erythrocytes in vitro by the malaria parasite Plasmodium falciparum. Liposomes containing human band 3 were ten times more effective in inhibiting invasion than those with pig band 3 and six times more effective than liposomes containing human erythrocyte glycophorin. Liposomes alone or liposomes containing erythrocyte glycolipids did not inhibit invasion. These results suggest that band 3 participates in the invasion process in a step involving a specific, high-affinity interaction between band 3 and some component of the parasite.

  16. Plasmodium falciparum--malaria in pregnant African immigrants often goes unrecognized.

    PubMed

    Kantele, Anu; Siikamäki, Heli; Hannila-Handelberg, Tuula; Laitinen, Kalevi; Rombo, Lars

    2012-12-01

    We report four cases of asymptomatic Plasmodium falciparum malaria in pregnant African women. They had immigrated to Finland 3 to 13 months earlier. The disease was revealed only by anemia. The diagnosis relied on blood smear which showed a parasitemia <0.2% in three cases. Medical personnel should be informed about the possibility of afebrile forms of malaria in pregnant women even months after immigration. Very low levels of parasitemia may call for a more sensitive diagnostic approach such as polymerase chain reaction. © 2012 International Society of Travel Medicine.

  17. Synthesis of small nuclear ribonucleoprotein particles by the malarial parasite Plasmodium falciparum.

    PubMed Central

    Francoeur, A M; Gritzmacher, C A; Peebles, C L; Reese, R T; Tan, E M

    1985-01-01

    Sera from patients with autoimmune diseases have been used to identify small nuclear ribonucleoprotein particles (snRNPs) present in higher eukaryotic cells and also in dinoflagellates. Previously these sera have not detected crossreactive snRNP protein antigens of other lower eukaryotes such as yeast, Tetrahymena, or Dictyostelium. We report that anti-Sm, anti-U1-RNP, and anti-La/SS-B human antisera react with specific snRNP protein antigens synthesized by the protozoan Plasmodium falciparum, the human malarial parasite. These results suggest that the structure and antigenicity (and thus probably the function) of snRNPs have been widely conserved in eukaryote evolution. Images PMID:2582421

  18. Integrative omics analysis. A study based on Plasmodium falciparum mRNA and protein data

    PubMed Central

    2014-01-01

    Background Technological improvements have shifted the focus from data generation to data analysis. The availability of large amounts of data from transcriptomics, protemics and metabolomics experiments raise new questions concerning suitable integrative analysis methods. We compare three integrative analysis techniques (co-inertia analysis, generalized singular value decomposition and integrative biclustering) by applying them to gene and protein abundance data from the six life cycle stages of Plasmodium falciparum. Co-inertia analysis is an analysis method used to visualize and explore gene and protein data. The generalized singular value decomposition has shown its potential in the analysis of two transcriptome data sets. Integrative Biclustering applies biclustering to gene and protein data. Results Using CIA, we visualize the six life cycle stages of Plasmodium falciparum, as well as GO terms in a 2D plane and interpret the spatial configuration. With GSVD, we decompose the transcriptomic and proteomic data sets into matrices with biologically meaningful interpretations and explore the processes captured by the data sets. IBC identifies groups of genes, proteins, GO Terms and life cycle stages of Plasmodium falciparum. We show method-specific results as well as a network view of the life cycle stages based on the results common to all three methods. Additionally, by combining the results of the three methods, we create a three-fold validated network of life cycle stage specific GO terms: Sporozoites are associated with transcription and transport; merozoites with entry into host cell as well as biosynthetic and metabolic processes; rings with oxidation-reduction processes; trophozoites with glycolysis and energy production; schizonts with antigenic variation and immune response; gametocyctes with DNA packaging and mitochondrial transport. Furthermore, the network connectivity underlines the separation of the intraerythrocytic cycle from the gametocyte and

  19. Changes in repeat number, sequence, and reading frame in S-antigen genes of Plasmodium falciparum.

    PubMed Central

    Saint, R B; Coppel, R L; Cowman, A F; Brown, G V; Shi, P T; Barzaga, N; Kemp, D J; Anders, R F

    1987-01-01

    The S antigens from different isolates of Plasmodium falciparum exhibit extensive size, charge, and serological diversity. We show here that the S-antigen genes behave as multiple alleles of a single locus. The size heterogeneity results from different numbers, lengths, and/or sequences of tandem repeat units encoded within the S-antigen genes. Two genes studied here encode antigenically different S antigens but nevertheless have closely related tandem repeat sequences. We show that antigenic differences can arise because repeats are translated in different reading frames. Images PMID:3313007

  20. Transport of lactate and pyruvate in the intraerythrocytic malaria parasite, Plasmodium falciparum.

    PubMed Central

    Elliott, J L; Saliba, K J; Kirk, K

    2001-01-01

    The mature, intraerythrocytic form of the human malaria parasite, Plasmodium falciparum, is reliant on glycolysis for its energetic requirements. It produces large quantities of lactic acid, which have to be removed from the parasite's cytosol to maintain the cell's integrity and metabolic viability. Here we show that the monocarboxylates lactate and pyruvate are both transported across the parasite's plasma membrane via a H(+)/monocarboxylate symport process that is saturable and inhibited by the bioflavonoid phloretin. The results provide direct evidence for the presence at the parasite surface of a H(+)-coupled monocarboxylate transporter with features in common with members of the MCT (monocarboxylate transporter) family of higher eukaryotes. PMID:11311136

  1. A flow cytometry-based assay for measuring invasion of red blood cells by Plasmodium falciparum.

    PubMed

    Bei, Amy K; Desimone, Tiffany M; Badiane, Aida S; Ahouidi, Ambroise D; Dieye, Tandakha; Ndiaye, Daouda; Sarr, Ousmane; Ndir, Omar; Mboup, Souleymane; Duraisingh, Manoj T

    2010-04-01

    Variability in the ability of the malaria parasite Plasmodium falciparum to invade human erythrocytes is postulated to be an important determinant of disease severity. Both the parasite multiplication rate and erythrocyte selectivity are important parameters that underlie such variable invasion. We have established a flow cytometry-based method for simultaneously calculating both the parasitemia and the number of multiply-infected erythrocytes. Staining with the DNA-specific dye SYBR Green I allows quantitation of parasite invasion at the ring stage of parasite development. We discuss in vitro and in vivo applications and limitations of this method in relation to the study of parasite invasion.

  2. Antimalarial Effect of 3-Methoxy-1,2-Dioxetanes on the Erythrocytic Cycle of Plasmodium falciparum.

    PubMed

    Lopes, Nicolas S; Yoshitake, Ariane M; Silva, Adriana F; Oliveira, Vani X; Silva, Leandro S; Pinheiro, Ana A S; Ciscato, Luiz Francisco M L

    2015-12-01

    The antimalarial activity of peroxides most likely originates from their interaction with iron(II) species located inside the malaria parasite, which forms destructive radical species through a Fenton-like mechanism. This article reports the first evaluation of the in vitro antimalarial activity of three peroxides of the class 1,2-dioxetanes against Plasmodium falciparum; the results reveal that the studied 3-methoxy-1,2-dioxetanes display significant antimalarial activity, at a similar level as artemisinin and also that their reactivity toward iron(II) correlate linearly with their antimalarial activity. © 2015 John Wiley & Sons A/S.

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

    PubMed Central

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

    2014-01-01

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

  4. A four-year surveillance program for detection of Plasmodium falciparum chloroquine resistance in Honduras.

    PubMed

    Fontecha, Gustavo A; Sanchez, Ana L; Mendoza, Meisy; Banegas, Engels; Mejía-Torres, Rosa E

    2014-07-01

    Countries could use the monitoring of drug resistance in malaria parasites as an effective early warning system to develop the timely response mechanisms that are required to avert the further spread of malaria. Drug resistance surveillance is essential in areas where no drug resistance has been reported, especially if neighbouring countries have previously reported resistance. Here, we present the results of a four-year surveillance program based on the sequencing of the pfcrt gene of Plasmodium falciparum populations from endemic areas of Honduras. All isolates were susceptible to chloroquine, as revealed by the pfcrt "CVMNK" genotype in codons 72-76.

  5. Interconvertible geometric isomers of Plasmodium falciparum dihydroorotate dehydrogenase inhibitors exhibit multiple binding modes.

    PubMed

    McConkey, Glenn A; Bedingfield, Paul T P; Burrell, David R; Chambers, Nicholas C; Cunningham, Fraser; Prior, Timothy J; Fishwick, Colin W G; Boa, Andrew N

    2017-08-15

    Two new tricyclic β-aminoacrylate derivatives (2e and 3e) have been found to be inhibitors of Plasmodium falciparum dihydroorotate dehydrogenase (PfDHODH) with Ki 0.037 and 0.15μM respectively. (1)H and (13)C NMR spectroscopic data show that these compounds undergo ready cis-trans isomerisation at room temperature in polar solvents. In silico docking studies indicate that for both molecules there is neither conformation nor double bond configuration which bind preferentially to PfDHODH. This flexibility is favourable for inhibitors of this channel that require extensive positioning to reach their binding site. Copyright © 2017 Elsevier Ltd. All rights reserved.

  6. K13-Propeller Polymorphisms in Plasmodium falciparum Isolates from Patients in Mayotte in 2013 and 2014

    PubMed Central

    Torrentino-Madamet, Marylin; Collet, Louis; Lepère, Jean François; Benoit, Nicolas; Amalvict, Rémy; Ménard, Didier

    2015-01-01

    Plasmodium falciparum isolates were collected from 29 malaria patients treated with artemether-lumefantrine in Mayotte in 2013 and 2014. Twenty-four cases (83%) consisted of imported malaria. Seventeen percent of the isolates presented mutations in one of the six K13-propeller blades (N490H, F495L, N554H/K, and E596G). A total of 23.8% of the isolates from the Union of Comoros showed K13-propeller polymorphisms. Three of the 18 isolates (16.7%) from Grande Comore showed polymorphisms (N490H, N554K, and E596G). PMID:26416865

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

    PubMed

    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.

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

    NASA Astrophysics Data System (ADS)

    Sharma, S. K.

    2012-12-01

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

  9. Absolute stability and Hopf bifurcation in a Plasmodium falciparum malaria model incorporating discrete immune response delay.

    PubMed

    Ncube, Israel

    2013-05-01

    We consider the absolute stability of the disease-free equilibrium of an intra-host Plasmodium falciparum malarial model allowing for antigenic variation within a single species. Antigenic variation can be viewed as an adaptation of the parasite to evade host defence [2]. The model was recently developed in [3-6]. The host's immune response is compartmentalised into reactions to major and minor epitopes. The immune response mounted by the human host is delayed, where, for simplicity, the delay is assumed to be discrete. We investigate the resulting characteristic equation, with a view to establishing absolute stability criteria and computing the Hopf bifurcation of the disease-free equilibrium.

  10. Computational insights into the suicide inhibition of Plasmodium falciparum Fk506-binding protein 35.

    PubMed

    MacDonald, Corey A; Boyd, Russell J

    2015-08-15

    Malaria is a parasite affecting millions of people worldwide. With the risk of malarial resistance reaching catastrophic levels, novel methods into the inhibition of this disease need to be prioritized. The exploitation of active site differences between parasitic and human peptidyl-prolyl cis/trans isomerases can be used for suicide inhibition, effectively poisoning the parasite without affecting the patient. This method of inhibition was explored using Plasmodium falciparum and Homo sapiens Fk506-binding proteins as templates for quantum mechanics/molecular mechanics calculations. Modification of the natural substrate has shown suicide inhibition is a valid approach for novel anti-malarials with little risk for parasitic resistance.

  11. Targeting Plasmodium falciparum protein kinases with adenosine analogue-oligoarginine conjugates.

    PubMed

    Lavogina, Darja; Budu, Alexandre; Enkvist, Erki; Hopp, Christine S; Baker, David A; Langsley, Gordon; Garcia, Celia R S; Uri, Asko

    2014-03-01

    During the last decade, a vast number of inhibitors, ligands and fluorescent probes have evolved for mammalian protein kinases; however, the suitability of these compounds for studies of evolutionarily divergent eukaryotes has mostly been left beyond the scope of research. Here, we examined whether adenosine analogue-oligoarginine conjugates that had been extensively characterized as efficient inhibitors of the human protein kinases are applicable for targeting Plasmodium protein kinases. We demonstrated that ARCs were not only able to bind to and inhibit a representative member of Plasmodium falciparum kinome (cGMP-dependent protein kinase) in biochemical assay, but also affected the general phosphorylation levels in parasites released from the infected red blood cells upon saponin treatment. These findings urge advantaging of already existing biochemical tools, whose initially generic, but intrinsically "tunable" selectivity profiles could be used for dissection of signaling pathways outside the initially defined group of biological targets. Copyright © 2014 Elsevier Inc. All rights reserved.

  12. Molecular surveillance of mutations in the cytochrome b gene of Plasmodium falciparum in Gabon and Ethiopia

    PubMed Central

    Gebru, Tamirat; Hailu, Asrat; Kremsner, Peter G; Kun, Jürgen FJ; Grobusch, Martin P

    2006-01-01

    Background Atovaquone is part of the antimalarial drug combination atovaquone-proguanil (Malarone®) and inhibits the cytochrome bc1 complex of the electron transport chain in Plasmodium spp. Molecular modelling showed that amino acid mutations are clustered around a putative atovaquone-binding site resulting in a reduced binding affinity of atovaquone for plasmodial cytochrome b, thus resulting in drug resistance. Methods The prevalence of cytochrome b point mutations possibly conferring atovaquone resistance in Plasmodium falciparum isolates in atovaquone treatment-naïve patient cohorts from Lambaréné, Gabon and from South Western Ethiopia was assessed. Results Four/40 (10%) mutant types (four different single polymorphisms, one leading to an amino acid change from M to I in a single case) in Gabonese isolates, but all 141/141 isolates were wild type in Ethiopia were found. Conclusion In the absence of drug pressure, spontaneous and possibly resistance-conferring mutations are rare. PMID:17118179

  13. Rapid detection of Plasmodium falciparum with isothermal recombinase polymerase amplification and lateral flow analysis

    PubMed Central

    2014-01-01

    Background Nucleic acid amplification is the most sensitive and specific method to detect Plasmodium falciparum. However the polymerase chain reaction remains laboratory-based and has to be conducted by trained personnel. Furthermore, the power dependency for the thermocycling process and the costly equipment necessary for the read-out are difficult to cover in resource-limited settings. This study aims to develop and evaluate a combination of isothermal nucleic acid amplification and simple lateral flow dipstick detection of the malaria parasite for point-of-care testing. Methods A specific fragment of the 18S rRNA gene of P. falciparum was amplified in 10 min at a constant 38°C using the isothermal recombinase polymerase amplification (RPA) method. With a unique probe system added to the reaction solution, the amplification product can be visualized on a simple lateral flow strip without further labelling. The combination of these methods was tested for sensitivity and specificity with various Plasmodium and other protozoa/bacterial strains, as well as with human DNA. Additional investigations were conducted to analyse the temperature optimum, reaction speed and robustness of this assay. Results The lateral flow RPA (LF-RPA) assay exhibited a high sensitivity and specificity. Experiments confirmed a detection limit as low as 100 fg of genomic P. falciparum DNA, corresponding to a sensitivity of approximately four parasites per reaction. All investigated P. falciparum strains (n = 77) were positively tested while all of the total 11 non-Plasmodium samples, showed a negative test result. The enzymatic reaction can be conducted under a broad range of conditions from 30-45°C with high inhibitory concentration of known PCR inhibitors. A time to result of 15 min from start of the reaction to read-out was determined. Conclusions Combining the isothermal RPA and the lateral flow detection is an approach to improve molecular diagnostic for P. falciparum in

  14. Rapid detection of Plasmodium falciparum with isothermal recombinase polymerase amplification and lateral flow analysis.

    PubMed

    Kersting, Sebastian; Rausch, Valentina; Bier, Frank Fabian; von Nickisch-Rosenegk, Markus

    2014-03-15

    Nucleic acid amplification is the most sensitive and specific method to detect Plasmodium falciparum. However the polymerase chain reaction remains laboratory-based and has to be conducted by trained personnel. Furthermore, the power dependency for the thermocycling process and the costly equipment necessary for the read-out are difficult to cover in resource-limited settings. This study aims to develop and evaluate a combination of isothermal nucleic acid amplification and simple lateral flow dipstick detection of the malaria parasite for point-of-care testing. A specific fragment of the 18S rRNA gene of P. falciparum was amplified in 10 min at a constant 38°C using the isothermal recombinase polymerase amplification (RPA) method. With a unique probe system added to the reaction solution, the amplification product can be visualized on a simple lateral flow strip without further labelling. The combination of these methods was tested for sensitivity and specificity with various Plasmodium and other protozoa/bacterial strains, as well as with human DNA. Additional investigations were conducted to analyse the temperature optimum, reaction speed and robustness of this assay. The lateral flow RPA (LF-RPA) assay exhibited a high sensitivity and specificity. Experiments confirmed a detection limit as low as 100 fg of genomic P. falciparum DNA, corresponding to a sensitivity of approximately four parasites per reaction. All investigated P. falciparum strains (n=77) were positively tested while all of the total 11 non-Plasmodium samples, showed a negative test result. The enzymatic reaction can be conducted under a broad range of conditions from 30-45°C with high inhibitory concentration of known PCR inhibitors. A time to result of 15 min from start of the reaction to read-out was determined. Combining the isothermal RPA and the lateral flow detection is an approach to improve molecular diagnostic for P. falciparum in resource-limited settings. The system requires none or

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

    PubMed Central

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

    2015-01-01

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

  16. Widespread occurrence of lysine methylation in Plasmodium falciparum proteins at asexual blood stages

    PubMed Central

    Kaur, Inderjeet; Zeeshan, Mohammad; Saini, Ekta; Kaushik, Abhinav; Mohmmed, Asif; Gupta, Dinesh; Malhotra, Pawan

    2016-01-01

    Post-transcriptional and post-translational modifications play a major role in Plasmodium life cycle regulation. Lysine methylation of histone proteins is well documented in several organisms, however in recent years lysine methylation of proteins outside histone code is emerging out as an important post-translational modification (PTM). In the present study we have performed global analysis of lysine methylation of proteins in asexual blood stages of Plasmodium falciparum development. We immunoprecipitated stage specific Plasmodium lysates using anti-methyl lysine specific antibodies that immunostained the asexual blood stage parasites. Using liquid chromatography and tandem mass spectrometry analysis, 570 lysine methylated proteins at three different blood stages were identified. Analysis of the peptide sequences identified 605 methylated sites within 422 proteins. Functional classification of the methylated proteins revealed that the proteins are mainly involved in nucleotide metabolic processes, chromatin organization, transport, homeostatic processes and protein folding. The motif analysis of the methylated lysine peptides reveals novel motifs. Many of the identified lysine methylated proteins are also interacting partners/substrates of PfSET domain proteins as revealed by STRING database analysis. Our findings suggest that the protein methylation at lysine residues is widespread in Plasmodium and plays an important regulatory role in diverse set of the parasite pathways. PMID:27762281

  17. Decreasing pfmdr1 Copy Number Suggests that Plasmodium falciparum in Western Cambodia Is Regaining In Vitro Susceptibility to Mefloquine

    PubMed Central

    Lim, Pharath; Dek, Dalin; Try, Vorleak; Sreng, Sokunthea; Suon, Seila

    2015-01-01

    Dihydroartemisinin-piperaquine is the current frontline artemisinin combination therapy (ACT) for Plasmodium falciparum malaria in Cambodia but is now failing in several western provinces. To investigate artesunate plus mefloquine (AS+MQ) as a replacement ACT, we measured the prevalence of multiple pfmdr1 copies—a molecular marker for MQ resistance—in 844 P. falciparum clinical isolates collected in 2008 to 2013. The pfmdr1 copy number is decreasing in Western Cambodia, suggesting that P. falciparum is regaining in vitro susceptibility to MQ. PMID:25712365

  18. New quinoline derivatives demonstrate a promising antimalarial activity against Plasmodium falciparum in vitro and Plasmodium berghei in vivo.

    PubMed

    Soares, Roberta Reis; da Silva, José Marcio Fernandes; Carlos, Bianca Cecheto; da Fonseca, Camila Campos; de Souza, Laila Salomé Araújo; Lopes, Fernanda Valério; de Paula Dias, Rafael Mafra; Moreira, Paulo Otávio Lourenço; Abramo, Clarice; Viana, Gustavo Henrique Ribeiro; de Pila Varotti, Fernando; da Silva, Adilson David; Scopel, Kézia Katiani Gorza

    2015-06-01

    Malaria continues to be an important public health problem in the world. Nowadays, the widespread parasite resistance to many drugs used in antimalarial therapy has made the effective treatment of cases and control of the disease a constant challenge. Therefore, the discovery of new molecules with good antimalarial activity and tolerance to human use can be really important in the further treatment of the disease. In this study we have investigated the antiplasmodial activity of 10 synthetic compounds derived from quinoline, five of them combined to sulfonamide and five to the hydrazine or hydrazide group. The compounds were evaluated according to their cytotoxicity against HepG2 and HeLa cell lines, their antimalarial activity against CQ-sensitive and CQ-resistant Plasmodium falciparum strains and, finally, their schizonticide blood action in mice infected with Plasmodium berghei NK65. The compounds exhibited no cytotoxic action in HepG2 and HeLa cell lines when tested up to a concentration of 100 μg/mL. In addition, the hydrazine or hydrazide derivative compounds were less cytotoxic against cell lines and more active against CQ-sensitive and CQ-resistant P. falciparum strains, showing high SI (>1000 when SI was calculated using the CC50 from the 3D7 strain as reference). When tested in vivo, the hydrazine derivative 1f compound showed activity against the development of blood parasites similar to that observed with CQ, the reference drug. Interestingly, the 1f compound demonstrated the best LipE value (4.84) among all those tested in vivo. Considering the in vitro and in vivo activities of the compounds studied here and the LipE values, we believe the 1f compound to be the most promising molecule for further studies in antimalarial chemotherapy. Copyright © 2015 Elsevier Ltd. All rights reserved.

  19. Influence of host iron status on Plasmodium falciparum infection

    PubMed Central

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

    2014-01-01

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

  20. The spectrum of retinopathy in adults with Plasmodium falciparum malaria.

    PubMed

    Maude, Richard J; Beare, Nicholas A V; Abu Sayeed, Abdullah; Chang, Christina C; Charunwatthana, Prakaykaew; Faiz, M Abul; Hossain, Amir; Yunus, Emran Bin; Hoque, M Gofranul; Hasan, Mahtab Uddin; White, Nicholas J; Day, Nicholas P J; Dondorp, Arjen M

    2009-07-01

    A specific retinopathy has been described in African children with cerebral malaria, but in adults this has not been extensively studied. Since the structure and function of the retinal vasculature greatly resembles the cerebral vasculature, study of retinal changes can reveal insights into the pathophysiology of cerebral malaria. A detailed observational study of malarial retinopathy in Bangladeshi adults was performed using high-definition portable retinal photography. Retinopathy was present in 17/27 adults (63%) with severe malaria and 14/20 adults (70%) with cerebral malaria. Moderate or severe retinopathy was more frequent in cerebral malaria (11/20, 55%) than in uncomplicated malaria (3/15, 20%; P=0.039), bacterial sepsis (0/5, 0%; P=0.038) or healthy controls (0/18, 0%; P<0.001). The spectrum of malarial retinopathy was similar to that previously described in African children, but no vessel discolouration was observed. The severity of retinal whitening correlated with admission venous plasma lactate (P=0.046), suggesting that retinal ischaemia represents systemic ischaemia. In conclusion, retinal changes related to microvascular obstruction were common in adults with severe falciparum malaria and correlated with disease severity and coma, suggesting that a compromised microcirculation has important pathophysiological significance in severe and cerebral malaria. Portable retinal photography has potential as a valuable tool to study malarial retinopathy.