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Publications (3)4.2 Total impact

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    ABSTRACT: The HIV-1 CRF01_AE gag gene was modified by codon restriction for Mycobacterium spp. and transformed into BCG; and it was designated as rBCG/codon optimized gagE. This produced 11 fold higher HIV-1 gag protein expression than the recombinant native gene rBCG/HIV-1gagE. In mice, CTL activity could be induced either by a single immunization of the codon optimized construct or by using it as a priming antigen in the prime-boost modality with recombinant Vaccinia virus expressing native HIV-1 gag. Specific secreted cytokine responses were also investigated. Only when rBCG gag was codon optimized did the prime-boost immunization produce significantly enhanced IFN-gamma and IL-2 secretion indicating recognition via CD4+ and CD8+ T cells, and these responses seemed to be codon optimized immunogen dose-responsive. On contrary, the prime-boost vaccination using an equal amount of native rBCG/HIV-1gagE instead, or a single rBCG/codon optimized gagE immunization, had no similar effect on the cytokine secretion. These findings suggest that the use of recombinant codon BCG construct with recombinant Vaccinia virus encoding CRF01_AE gag as the prime-boost HIV vaccine candidate, will induce CD4+ Th1 and CD8+ T cell cytokine secretions in addition to enhancing CD8+ CTL response.
    Immunological Investigations 01/2009; 38(8):762-79. · 1.47 Impact Factor
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    ABSTRACT: 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.
    Molecular and Biochemical Parasitology 03/2000; 105(2):215-22. · 2.73 Impact Factor
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    ABSTRACT: Mitochondria of the human malarial parasite Plasmodium falciparum in sexual blood stages (or gametocytes) had been structurally different from those of asexual blood stages of their life cycle in human host. We report here the existence of mitochondrial heterogeneity based on their characteristics of ultrastructural morphology in the asexual and sexual blood stages of P. falciparum from in vitro continuous cultures. Mitochondria in the sexual stage-parasites were more numerous and contained a greater density of cristae than the organelles in the asexual stage-parasites. It was demonstrated that there were apparent variations in size and appearance of the mitochondria between the male and female parasites of the sexual gametocytic stages. Mitochondrial oxygen consumption of the sexual stage-parasites was relatively low, and it was not different from the asexual blood stage-parasites. However, both stages of the parasites' growth and their oxygen consumption were found to be sensitive to atovaquone, cyanide and 5-fluoroorotate which were inhibitors of mitochondrial electron transport system and pyrimidine bio- synthetic pathway, respectively. Therefore, the role of mitochondrial organelles with different morpho- logical properties in the asexual and sexual stages of parasite's development remains to be elucidated.