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  • 1
    Electronic Resource
    Electronic Resource
    Protective Role of γδ T Lymphocytes during Plasmodium falciparum Infection (2005)
    Oxford, UK : Blackwell Science Inc
    The @journal of eukaryotic microbiology 52 (2005), S. 0 
    Details
    ISSN: 1550-7408
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Human T γδ lymphocytes, bearing Vγ9 Vδ2 chains, constitute a small proportion (1–5%) of the lymphocytes in the blood. These cells recognize nonpeptidic molecules such as phosphoantigens, intermediary metabolites products by microorganisms, including parasites. These antigens are recognized in the absence of molecules CMH. Our previous results have shown that Plasmodium falciparum synthetize phosphoantigen, intermediary products of the Rohmer pathway. These phosphoantigens are able to induce the proliferation of T γδ lymphocytes, producing pro-inflammatory cytokines and providing a parasitotoxic activity against parasitized red blood cells. Also, during the acute phase of infection, these lymphocytes increase both in percentage and numbers. Today, the biological role of T γδ lymphocytes remains poorly understood. Indeed, these lymphocytes are found in primates but there is no equivalent in rodents. We decided to study this population in the infection model Plasmodium falciparum/spleen intact Saimiri scirieus. In this monkey, we found a population of TVγ9 (representing 0.2–1% of total lymphocytes in the peripheral blood) which react with phosphoantigens as do human TVγ9 cells. Activation kinetics of these cells in infected monkeys show an early activation occuring on the 6th day of infection, while the CD4 T activation starts at day 10. Also, we observed an important increase of numbers and percentages of these TVγ9. Their maximal peak coincides with the beginning of parasite clearance. Together, these data associated with parasitotoxic activity in vitro argue for a role of TVγ9 cells in parasitemia control, particulary during primary infection.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1550-7408.2005.05202003_3_13.x
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  • 2
    Electronic Resource
    Electronic Resource
    Revisiting Putative Functional Properties of the Plasmodium falciparum Pf155/RESA Protein Using Genetically Engineered Parasites (2005)
    Oxford, UK : Blackwell Science Inc
    The @journal of eukaryotic microbiology 52 (2005), S. 0 
    Details
    ISSN: 1550-7408
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Pf155/RESA (Ring Infected Erythrocyte Surface Antigen), is a Plasmodium falciparum protein discharged by the dense granules of merozoites during invasion and exported to the inner face of the erythrocyte membrane, where it interacts with spectrin in the young stages. Chromosome 1 subtelomeric deletion, eliminating amongst others the resa gene, may occur during adaptation of parasite isolates to in vitro culture. This is accompanied by erythrocyte membrane modifications of the red blood cell, such as increased adhesion and effect on membrane rigidity. It has been proposed that RESA was likely to contribute to these functional and rheological modifications. To assess this, we have constructed resa knock-out parasites in the FUP/CB strain. This results in negativating the erythrocyte membrane immunofluorescence of glutaraldehyde-fixed red blood cells (EMIF), indicating that RESA is critical for EMIF reactivity of hyperimmune human sera. Phenotypic and functional analysis of resa k.o. parasites indicated that loss of RESA expression neither affects membrane rigidity nor CD36 binding under flow conditions. Furthermore, infection of Saimiri sciureus monkeys showed that resa gene deletion does not account on its own for the greater adaptation and parasite virulence in this model.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1550-7408.2005.05202003_3_9.x
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  • 3
    Electronic Resource
    Electronic Resource
    Plasmodium falciparum: a comparative analysis of the genetic diversity in malaria-mesoendemic areas of Brazil and Madagascar (2000)
    Springer
    Parasitology research 86 (2000), S. 692-698 
    Details
    ISSN: 1432-1955
    Keywords: AbbreviationsMSP-l, MSP-2 Merozoite surface antigens 1 and 2 ; TRAP Thrombospondin-related anonymous protein ; PCR Polymerase chain reaction ; EM Entomologic inoculation rate ; RFLP Restriction-fragment-length polymorphism ; CSP Circumsporozoite protein ; GLURP Glutamine-rich protein ; SDS Sodium dodecyl sulfate ; EDTA Ethylenediaminetetraacetic acid
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract For a better definition of the polymorphic features of Plasmodium falciparum parasite populations, the polymerase chain reaction (PCR) typing technique was used to investigate the genetic diversity and complexity of parasites harbored by acute P. falciparum carriers from three yet unexplored malaria-mesoendemic areas with different transmission levels: two localities in northwestern Brazil (Ariquemes and Porto Velho) and a village in Madagascar (Ankazobe). A total of 89 DNA samples were analyzed by amplification of polymorphic domains from genes encoding merozoite surface antigens 1 and 2 (MSP-1, MSP-2) and thrombospondin-related anonymous protein (TRAP) and by hybridization with allelic-family-specific probes or random-fragment-length polymorphism (RFLP). In all three localities, extensive polymorphism was observed for each marker, but the MSP-2 central repeat was the most diverse one. Similar levels of genetic diversity, allelic frequency, and infection complexity were observed in the two Brazilian localities, although the isolates had been sampled at 2-year intervals, suggesting the stability of the infecting parasite populations presenting in these regions of the Brazilian Amazon. Unexpectedly, although the entomologic inoculation rate was at least 3 times lower in Ankazobe than in the Brazilian areas, Malagasi samples appeared more complex than the Brazilian ones. The implications of these data with regard to parasite population-dynamics studies are discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/PL00008554
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