水稻条纹病毒突破介体灰飞虱中肠屏障的机制

How to overcome the midgut barriers in vector insect is a critical step for persistent-propagative viruses because it controls transmission process, thus directly influencing virus ecology and disease epidemiology. However, the mechanisms enabling virus overcoming the midgut barriers have been poorly understood. Rice stripe virus (RSV), a member of the genus Tenuivirus, is responsible for significant yield losses in rice production in temperate and subtropical East Asia. RSV is transmitted in a circulative, persistent, propagative manner by the small brown planthopper (Laodelphax striatellus). High densities of this insect can damage cereal crops in the field directly by feeding, but low densities of RSV-infected insects can result in even greater yield losses by transmitting RSV. In this project, we want to investigate the molecular mechanisms of RSV overcoming the midgut barriers its insect vector (L. striatellus). Firstly, we will take advantage of several biological tools to find the roles of Ls-sugar transporter 6 (Ls-ST6) and vesicle-associated membrane protein (Ls-VAMP) in the process of overcoming the midgut barriers for successful transmission. Secondly, the mechanism will be studied using several techniques, including yeast two-hybrid assay, immunofluorescence, RNA interference, crystallization and structure analysis of viral and vector insect proteins. Through comparing the differences of key amino acids in the population of L. striatellus collected from many regions, with the variances in viruliferous percentage and transmission efficiency, we will get the reasons why rice stripe disease intermittent epidemics in China, and then propose the new model for the preestimate and forecast system of rice sripe disease. Our results also lead to propose a new strategy for controlling vector transmission.

持久增殖型植物病毒突破相应介体的中肠传播屏障是决定能否传毒与病害流行的最重要因素。本项目拟以水稻条纹病毒（RSV）及其介体灰飞虱为对象，在筛选获得与病毒互作的灰飞虱中肠蛋白基础上，系统研究RSV突破灰飞虱中肠屏障的分子机理。首先明确灰飞虱糖转运蛋白6和囊泡相关膜蛋白是如何与病毒互作而帮助病毒侵入中肠上皮细胞并扩散到邻近的细胞或血淋巴中，揭示病毒的介体传毒亲和性识别和专化性选择机理；然后研究田间灰飞虱不同种群RSV带毒率和传毒率与编码传毒蛋白的基因序列关系，结合病毒、寄主、介体和环境条件在病害暴发和流行中的关键作用分析，建立基于介体高效传毒分子特征的RSV流行预警体系。通过对RSV突破灰飞虱中肠侵入与扩散屏障机理的解析，为设计通过阻断病毒突破中肠屏障的能力，进而切断病毒在介体内有效循回的新型病害调控策略提供依据；也为在分子、细胞和群体水平上解析植物病毒病害间歇性暴发流行规律奠定理论基础。

持久增殖型植物病毒突破介体中肠传播屏障是决定能否传毒与病害流行的最重要因素。本项目在筛选与水稻条纹病毒（RSV）互作的灰飞虱中肠蛋白基础上，系统研究了RSV突破灰飞虱中肠屏障的分子机理。首先明确了灰飞虱糖转运蛋白6作为一个关键因子介导RSV成功侵染中肠上皮细胞，但是不影响病毒在细胞内的复制，病毒唑可通过抑制糖转运蛋白6的表达，显著降低了灰飞虱的获毒和传播效率。系统研究了飞虱体内的囊泡运输系统SNARE家族蛋白-囊泡相关膜蛋白7（VAMP7）和囊泡运输蛋白1a（Vti1a）在囊泡膜上与病毒粒体结合，使病毒粒体进入囊泡来参与病毒在中肠上皮细胞中的转运与扩散，揭示了植物病毒可以通过劫持囊泡克服介体昆虫中肠释放屏障的关键机制，为阻断病毒病的传播提供候选靶标。发现灰飞虱的细胞自噬能够抑制RSV的增殖，而成功逃脱介体细胞自噬降解作用的RSV病毒粒子能够进行复制，新合成的RSV-CP与介体灰飞虱的Atg3的互作，损害Atg3在自噬体形成过程中发挥功能，减少自噬体产生，防止自身降解进而实现RSV在灰飞虱中的长久生存。明确了不同地理种群灰飞虱的糖转运蛋白6基因序列差异与带毒率和传毒率的关系，以及灰飞虱自身微生物群体对个体发育与传毒的影响，提出了基于介体高效传毒的RSV流行预警体系与新型抗病策略。对灰飞虱传播的水稻重要病毒病害的暴发流行规律做了归纳总结，每年从水稻条纹叶枯病的流行地区调查并测定灰飞虱群体带毒率，所获结果及时提供给当地农业行政管理部门，用于病害的预测预报，有效地指导了水稻病毒病害的预测和防控工作。在PLoS Pathogens和Current Opinion in Virology等刊物上发表15篇学术论文，其中SCI学术论文14篇，中文期刊1篇，授权发明专利1项，参与出版专著1部。受邀6次在国际学术会议进行大会报告，国际培训班授课1次，培养硕博研究生12人。