Plasmodium falciparum gametocytogenesis

描述(申请人提供)：疟疾仍然是一个主要的世界卫生问题，每年导致100-200万人死亡。导致疟疾的疟原虫有一个多阶段的生命周期，这有助于它们逃避宿主免疫反应的能力。为了传播疟疾，寄生虫必须经历性分化成成熟的配子体，当蚊子在血餐中摄取这些配子体时，这些配子体可以受精并开始产孢子发育。在寄生虫的生命周期中，从无性复制到有性分化的关键转换的分子基础尚不清楚。我们的假设是，这种转变是由转录因子的激活启动的，转录因子调节影响配子体发生所需基因的表达。一旦确定了调控因素，就可以设计出抑制配子细胞生成的药物，这将阻止疟疾的传播。为了确定相关基因，从3D7株恶性疟原虫中分离出产生配子体(G+)和不产生配子体(G-)的品系。第一个具体目标将是使用全基因组微阵列分析来比较无性向有性转变期间从G+和G-克隆获得的mRNA。这种比较应该确定最早差异表达的基因。具体目标2将是分析参与调节这些基因配子体特异性表达的因素。将测试基因5‘和3’侧翼区驱动阶段特异性报告基因表达的能力，并通过辅以基序分析的启动子作图来确定所需的特定调控区。具体目标3将通过确定G+和G-寄生虫品系之间的遗传差异以及与特定目标2中确定的调节区相互作用的基因来鉴定诱导配子细胞发生所需的基因。配子细胞发生与所发现的遗传差异之间的关系将通过G-线的互补和野生型G+寄生虫的靶向基因干扰来进一步分析。这些信息应该提供新的候选基因，将来可以用来设计控制疟疾传播的新战略。

DESCRIPTION (provided by applicant): Malaria continues to be a major world health problem, killing1-2 million people annually. The Plasmodium parasites that cause malaria have a multistage life cycle, which contributes to their ability to evade host immune responses. For malaria transmission, the parasite must undergo sexual differentiation into mature gametocytes that, when taken up in a blood meal by a mosquito can fertilize and begin sporogonic development. The molecular basis for the critical switch from asexual replication to sexual differentiation in the parasite's life cycle is unknown. Our hypothesis is that this transition is initiated by the activation of transcription factors that regulate the expression of genes required to effect gametocytogenesis. Once the regulatory factors are identified, inhibitors could be designed to block gametocytogenesis, which would prevent malaria transmission. To identify the genes involved, Plasmodium falciparum gametocyte producing (G+) and non-producing (G-) parasite lines were derived from strain 3D7 parasites. The first Specific Aim will be to use whole genome microarray analysis to compare mRNA harvested from the G+ and G- clones during the asexual to sexual transition. This comparison should identify the earliest differentially expressed genes. Specific Aim 2 will be to analyze the factors involved in regulating the gametocyte-specific expression of these genes. The ability of the 5' and 3' flanking regions of the genes to drive stage-specific reporter gene expression will be tested and the specific regulatory regions required will be identified by promoter mapping supplemented with motif analysis. Specific Aim 3 will be to identify the genes required for the induction of gametocytogenesis by determining the genetic differences between the G+ and G- parasite lines, as well as the genes that interact with the regulatory regions identified in Specific Aim 2. The relationship between gametocytogenesis and the genetic differences found will be further analyzed by complementation of the G- line and targeted gene disruption of wild type G+ parasites. This information should provide new gene candidates that could be used in the future to design new strategies to control malaria transmission.