控制疟原虫子孢子发育的基因定位及其候选基因的鉴定

Malaria is a global infectious disease that inflicts a heavy health and economical burden on human beings, causing approximately one million deaths annually. Plasmodium parasites have a complex life cycle, involving various developmental stages in the Anopheles mosquito and human hosts. The development of mature infective sporozoites is critical for malaria transmission to humans. However, the molecular basis of oocyst development, sporozoite differentiation and egress of the sporozoites into the mosquito hemocoeal remains largely unknown. Our previous study found that a Plasmodium yoelii strain called BY265G had a defect in producing functional sporozoites after needle-passages in mosquito, whereas another parasite, NSM, could produce normal sporozoites and could complete the whole developmental cycle in mosquito normally. We propose here to perform genetic crosses using BY265G and NSM to map the gene(s) that controls the sporozoite development and infectivity, and to compare the genome sequences of the parents to identify the candidate mutations; if a candidate gene is identified from the mapping and sequence comparison, we'll investigate its functions by using reverse genetic approaches such as allelic exchange or gene knockout. The identification of genes underlying sporozoite development and elucidation of its molecular mechanisms may help design effective strategies to block parasite transmission and will be crucial for disease control and eradication.

疟疾是严重危害人类健康、影响经济发展的全球性寄生虫传染病，按蚊是疟疾传播媒介，疟原虫在按蚊体内能否发育为具感染力的成熟子孢子(Sp)是疟原虫能否传播流行的关键。目前有关疟原虫卵囊发育、Sp分化、以及Sp如何进入蚊体血腔的分子机制了解甚少。我们前期研究工作发现，约氏疟原虫（Plasmodium yoelii）虫株BY265G不能在按蚊体内发育为成熟Sp、并丧失了感染小鼠宿主的能力；而约氏疟原虫NSM为卵囊/Sp发育野生型虫株，其Sp具有正常侵染小鼠的能力。本项目拟通过构建遗传杂交组BY265G×NSM，遗传定位控制Sp发育的潜在基因，并对亲本的DNA序列进行比对以确定基因突变位点；同时使用等位基因位点替换、或基因敲除等反向遗传学技术，对候选基因进行功能性实验验证。鉴定控制Sp发育的候选基因和阐明Sp发育机制，为设计阻断疟原虫传播策略提供新的靶点和思路，乃至对根除疟疾提供重要信息和实验依据。