MOLECULAR DISSECTION OF P. FALCIPARUM SEXUAL DEVELOPMENT

疟疾寄生虫每年造成3亿至5亿人感染，200万至300万人死亡。 疟疾在脊椎动物宿主之间的传播涉及按蚊媒介中的专性发育周期。 性行为对于疟疾的传播是绝对必要的。 恶性疟原虫性别分化和发育的分子机制仍不清楚。 在最初的承诺性周期后，疟原虫配子体经历似乎是一个多步骤的生长和发育过程，可能涉及几个基因产物。 这项建议的目标是调查的功能参与的两种蛋白质（Pfg 27和Pfs 16），大量表达早期配子体。 我们最近通过同源重组破坏了Pfg 27基因，导致转化的寄生虫失去了性表型。 这些研究首次表明，Pfg 27，一种在I期和II期配子体中表达的蛋白质，对配子体发育至关重要。Pfs 16基因的破坏将进一步阐明恶性疟原虫的性分化过程。 对稳定转化的寄生虫的研究也将提供一个机会来评估转录控制机制、启动子的性阶段特异性和被破坏基因的互补作用。免疫化学和分子（酵母双杂交）方法的组合将被用来研究涉及Pfg 27和Pfs 16和其他细胞蛋白质的蛋白质-蛋白质相互作用。 这些研究可能会发现新的蛋白质作为相互作用的功能伙伴，从而推进我们的理解Pfg 27和Pfs 16的性分化和发展的传播能力的寄生虫的生物学作用。 因此，拟议的研究将提供一种新的分子遗传学方法来剖析恶性疟原虫性发育的机制。 这些信息可能会导致免疫和/或化疗武器的合理开发，以预防恶性疟原虫疟疾的传播。

Malaria parasites are responsible for 300-500 million infections and 2-3 million deaths annually. Transmission of malaria between vertebrate hosts involves an obligate sexual developmental cycle in the anopheline mosquito vector. The sexual stages are absolutely essential for malaria transmission. The molecular mechanisms underlying sexual differentiation and development in Plasmodium falciparum remain largely unknown. After the initial commitment to the sexual cycle, Plasmodium gametocytes undergo what appears to be a multi-step growth and development process, possibly involving several gene products. The goal of this proposal is to investigate the functional involvement of two proteins (Pfg27 and Pfs16), abundantly expressed early during gametocytogenesis. We have recently disrupted the gene for Pfg27 by homologous recombination, resulting in the loss of sexual phenotype in the transformed parasites. These studies for the first time have shown that Pfg27, a protein expressed in stage I and II gametocytes is critical for gametocyte development. Studies on Pfs16 disruption will further elucidate sexual differentiation process in P. falciparum. Investigations on stably transformed parasites will also offer an opportunity to evaluate transcriptional control mechanisms, sexual stage- specificity of promoters and complementation of disrupted genes. A combination of immunochemical and molecular (yeast-two-hybrid) approaches will be employed to investigate protein-protein interactions involving Pfg27 and Pfs16 and other cellular proteins. These studies could possibly identify novel proteins as interacting functional partners, thus advancing our understanding of the biological roles of Pfg27 and Pfs16 in the sexual differentiation and development of transmission competent parasites. The proposed studies will thus offer a novel molecular genetic approach to dissect mechanisms underlying sexual development in P. falciparum. Such information could lead to rational development of immunological and/or chemotherapeutic arsenal to prevent transmission of P. falciparum malaria.