发生于云南的烟草丛顶病是一类特殊的病害，由烟草丛顶病毒（TBTV）、烟草扭脉病毒（TVDV）、烟草丛顶病毒卫星RNA（TBTV-satRNA）及烟草扭脉病毒相关RNA（TVDVaRNA）等病原物复合侵染引起。该病害在自然情况下主要通过烟蚜传播，TVDV在烟蚜传播中起着非常重要的作用。鉴于烟草丛顶病病原物的特殊性及烟蚜传播对病害发生流行的重要性，本项目拟在前期工作基础上，通过构建烟草丛顶病主要病原物侵染性克隆及其可能与烟蚜传毒相关基因的缺失突变体，分析各主要病原物在烟蚜传播中的相互关系及作用；并利用免疫荧光标记技术与RNAi技术，解读TVDV在烟蚜体内的侵染循回过程，鉴定TVDV编码的与烟蚜传毒相关的关键因子，探讨TVDV的CP及其通读蛋白在烟蚜传播TBTV中的作用，分析TVDV CP对TBTV基因组RNA的异源包裹作用，揭示TVDV协助TBTV进行烟蚜传播的作用机理。

Tobacco bushy top disease occurred in Yunnan is a severe disease caused by mixed infection of Tobacco bushy top virus (TBTV), Tobacco vein distorting virus (TVDV), the satellite RNA of TBTV (TBTV-satRNA) and TVDV associated RNA (TVDVaRNA) . The disease is mainly transmitted by Myzus persicae in nature, and TVDV plays an important role in the aphid transmission. In consideration of the specific characteristics of the complex agents and the importance about aphid transmission in the disease occurrence and epidemic, this proposal aims to reveal the mechanism of TVDV assisting TBTV in the process of aphid transmission on the base of the previous related progresses on tobacco bushy top disease. This proposal also wants to discribe the relationship and interaction of different causal agent in Myzus persicae transmission through construction of the infectious clones and deletion mutants possibly related to aphid transmission of the complex agents. To show the infection and circulation route of TVDV in Myzus persicae and identify the key aphid transmission-related proteins encoded by TVDV using immunofluorescent labeling and RNA interference (RNAi) techniques. To discuss the roles about TVDV coat protein (CP) and readthrough (RT) protein in Myzus persicae transmission and demonstrate the encapsidation of TVDV CP for TBTV genomic RNA, and therefore reveal the mechanism about TVDV acting as an assistant virus of TBTV for Myzus persicae transmission. The results obtained will provide the foundation for the further study about the interaction between related viruses and aphid, and finally reveal the aphid transmission mechanism of tobacco bushy top disease agent complex.