植物病毒的经卵传播至介体昆虫后代的分子机制是学科的热点和难点科学问题。水稻矮缩病毒（RDV）主要由介体黑尾叶蝉以持久增殖型方式传播的，并能经卵传播到介体后代。前期研究表明RDV是从介体叶蝉卵巢下端的上皮鞘侵入卵母细胞的，其在经卵传播过程中可直接附着在初生细菌类共生菌（Sulcia和Nasuia）外周，表明RDV可能是借用了古老的叶蝉体内共生菌的入卵通道，从而较为轻易地突破昆虫经卵传播屏障。本项目拟利用细胞生物学、蛋白互作、抗体中和作用和抗生素或溶菌酶抑制共生菌生长等手段，研究RDV经卵传播的途径，鉴定与RDV外壳蛋白（P2或P8）直接互作的共生菌外膜蛋白，解析共生菌介导RDV入卵的分子机制；同时，研究RDV经卵传播过程中形成的昆虫—共生菌—病毒三者间的互作关系。研究结果将揭示病毒的经卵传播新机制，为探索更为接近自然条件下的虫传病毒病致灾机制和利用共生菌设计高效、可持续的病害控制策略提供理论

The molecular mechanisms of transovarial transmission of plant viruses in their insect vectors are the hot and difficult spot of study. Rice dwarf virus (RDV) is transmitted by the green rice leafhopper Nephotettix cincticeps in a persistent-propagative manner and is transovarially transmitted. Our previous studies find that Rice dwarf virus (RDV) first enters the epithelial plug at the posterior end of the insect female’s ovariole, then invades the oocyte. Furthermore, the RDV particles are found on the membrane surface of two kinds of primary bacterial symbionts (Sulcia and Nasuia) in the ovariole. Thus, RDV may directly exploit the ancient entering oocyte pathway of symbionts in leafhoppers, allowing the virus to easily overcome the transovarial transmission barrier. In this project, we will use the methods including cell biology, protein interaction, antibody neutralization and inhibition of symbionts growth by the treatment of antibiotics or lysozyme, to investigate the transovarial transmission route of RDV in leafhopper, to identify the outer membrane proteins of bacterial symbionts (Sulcia and Nasuia) which could directly interact with the outer capsid proteins of RDV (P2 or P8) , and to elucidate the molecular mechanisms underling the symbiont-mediated transovarial transmission of RDV in leafhoppers. We also will study the relationships among the insect, symbionts and virus during the transovarial transmission of RDV. The results will reveal a new mechanism of transovarial transmission of a virus in its insect vector, and will provide the theoretical basis for explaining how the insect-transmitted viral diseases become serious under natural conditions, and for designing how to efficiently and persistently control them by the use of insect symbionts.