Growth and survival of nearshore fishes in Lake Michigan

Illinois Department of Natural resources Grant/Contract No: F-138INHS Technical Report Prepared for Illinois Department of Natural resource

Functional analysis of the exported type IV HSP40 Protein PfGECO in <i>Plasmodium falciparum</i> gametocytes

During Plasmodium falciparum infection, host red blood cell (RBC) remodeling is required for the parasite's survival. Such modifications are mediated by the export of parasite proteins into the RBC that alter the architecture of the RBC membrane and enable cytoadherence. It is probable that some exported proteins also play a protective role against the host defense response. This may be of particular importance for the gametocyte stage of the life cycle that is responsible for malaria transmission, since the gametocyte remains in contact with blood as it proceeds through five morphological stages (I to V) during its 12-day maturation. Using microarray analysis, we identified several genes with encoded secretory or export sequences that were differentially expressed during early gametocytogenesis. One of these, PfGECO, encodes a predicted type IV heat shock protein 40 (HSP40) that we show is expressed in gametocyte stages I to IV and is exported to the RBC cytoplasm. HSPs are traditionally induced under stressful conditions to maintain homeostasis, but PfGECO expression was not increased upon heat shock, suggesting an alternate function. Targeted disruption of PfGECO indicated that the gene is not essential for gametocytogenesis in vitro, and quantitative reverse transcriptase PCR (RT-PCR) showed that there was no compensatory expression of the other type IV HSP40 genes. Although P. falciparum HSP40 members are implicated in the trafficking of proteins to the RBC surface, removal of PfGECO did not affect the targeting of other exported gametocyte proteins. This work has expanded the repertoire of known gametocyte-exported proteins to include a type IV HSP40, PfGECO

Inhibition of Plasmodium falciparum Oocyst Production by Membrane-Permeant Cysteine Protease Inhibitor E64d

During asexual intraerythrocytic growth, Plasmodium falciparum utilizes hemoglobin obtained from the host red blood cell (RBC) as a nutrient source. Papain-like cysteine proteases, falcipains 2 and 3, have been reported to be involved in hemoglobin digestion and are targets of current antimalarial drug development efforts. However, their expression during gametocytogenesis, which is required for malaria parasite transmission, has not been studied. Many of the available antimalarials do not inhibit development of sexual stage parasites, and therefore, the persistence of gametocytes after drug treatment allows continued transmission of the disease. In the work reported here, incubation of stage V gametocytes with membrane-permeant cysteine protease inhibitor E64d significantly inhibited oocyst production (80 to 100%). The same conditions inhibited processing of gametocyte-surface antigen Pfs230 during gametogenesis but did not alter the morphology of the food vacuole in gametocytes, inhibit emergence, or block male exflagellation. E64d reduced the level of oocyst production more effectively than that reported previously for falcipain 1-knockout parasites, suggesting that falcipains 2 and 3 may also be involved in malaria parasite transmission. However, in this study only falcipain 3 and not falcipain 2 was found to be expressed in stage V gametocytes. Interestingly, during gametocytogenesis falcipain 3 was transported into the red blood cell and by stage V was localized in vesicles along the RBC surface, consistent with a role during gamete emergence. The ability of a membrane-permeant cysteine protease inhibitor to significantly reduce malaria parasite transmission suggests that future drug design should include evaluation of gametogenesis and sporogonic development

A glycosylphosphatidylinositol anchor signal sequence enhances the immunogenicity of a DNA vaccine encoding Plasmodium falciparum sexual-stage antigen, Pfs230.

Item does not contain fulltextMammalian expression vectors encoding region C of malaria transmission-blocking vaccine candidate Pfs230 (aa 443-1132) with and without a 3' glycosylphosphatidylinositol (GPI) anchor signal sequence were tested for their immunogenicity in mice. The plasmid containing the GPI anchor signal sequence consistently induced higher titers of anti-Pfs230 antibodies using three delivery systems: intramuscular (i.m.), intradermal (i.d.), and gene gun (g.g.). In contrast, the isotype profile elicited varied depending on the delivery system and was not effected by the presence of the GPI anchor sequence. Both gene gun and intradermal administration induced primarily an IgG1 response, while intramuscular injection induced both IgG1 and IgG2a antibodies. Regardless of the mode of delivery, all the plasmids encoding Pfs230 region C primed for a mixed IgG1/IgG2a response to an intraperitoneal (i.p.) injection of E. coli-produced recombinant Pfs230 region C. None of these vaccination strategies were more effective than r230/MBP.C alone in generating malaria transmission-blocking immunity