疟疾是由疟原虫引起并经雌性按蚊吸血传播，蚊虫控制是对抗疟疾的重要措施。疟原虫需要在按蚊中肠内完成发育增殖才能传染，此间大量疟原虫被抑制，其中肠道共生细菌在按蚊抗疟上起重要作用，但有关共生菌抗疟的具体分子机理知之甚少，同时我国疟蚊肠道共生菌在按蚊抗疟上的作用和机制还末见报道。前期研究中我们建立了分离肠道共生细菌的新方法，已经从云南采集的中华按蚊分离到一株高效抗疟的肠道共生细菌，本项目在前期研究基础上运用16S测序和分离培养法系统研究不同地区中华按蚊肠道共生菌群结构与多样性，通过体内和体外抗疟测定筛选获得多株高效抗疟共生菌株，综合运用转录组、代谢组和反向遗传学等研究手段，系统揭示不同抗疟共生菌协同按蚊抗疟的分子机制，为发展利用我国按蚊肠道共生菌阻断疟疾传播的新策略提供理论和技术基础。本项目的研究也为其他蚊媒传染病的防控提供新思路，并丰富对媒介昆虫传播疾病的生物学基础及其分子机制的认识。

Malaria is caused by Plasmodium parasites that are transmitted through the bite of infected female anopheline mosquitoes. Therefore, eliminating the mosquitoes or interfering with their ability to support the parasite development will block transmission. Transmission of the malaria parasite requires the completion of a complex developmental cycle in vector mosquitoes, and the most vulnerable stages of Plasmodium development in the vector mosquito occur in the midgut lumen, where an overwhelming majority of ingested parasites are killed. Several studies have shown mosquito’s midgut bacteria have an important role in modulating the mosquito's vectorial capacity by inhibiting the development of Plasmodium, suggesting the promising application of natural gut symbiotic bacteria of the mosquito as a means of preventing malaria transmission. However, the exact mechanisms by which the midgut bacteria prevent malaria transmission have not been elucidated. In addition, little is known about the midgut symbiotic microbiota and their interactions with Plasmodium infection in Anopheles sinensis, the main malaria vector in China. In this project we will use our established new method to isolate symbiotic bacteria, and characterize the composition and structure of symbiotic gut microbiota of field-collected blood-fed A. sinensis in China by using MiSeq sequencing of the 16S rDNA and culture method. We then screen for bacterial strains that strongly inhibit Plasmodium development in the mosquito midgut, and uncover the mechanisms of how these natural bacteria render the mosquito resistance to Plasmodium infection.