Towards a better understanding of molecular virus-plant interactions: componenets and intracellular trafficking of viral genome translation/replication complexes

植物病毒是专性的细胞内寄生虫，感染许多主要农作物，每年在世界上造成数十亿美元的损失。马铃薯Y病毒是植物病毒中最大的一类，约占所有已知植物病毒的30%。马铃薯Y病毒包括芜菁花叶病毒(TuMV)、三叶草黄脉病毒(ClYVV)、李痘病毒(PPV)、大豆花叶病毒(SMV)、马铃薯Y病毒(PVY)和烟草蚀刻病毒(TEV)。植物马铃薯Y病毒和其他植物病毒的共同特征之一是它们的基因组相对较小，蛋白质编码能力非常有限。因此，这些病毒病原体必须与宿主细胞相互作用，以招募一系列宿主蛋白(宿主因子)和代谢物来完成它们的生命周期。最近关于病毒-植物相互作用的研究已经确定了几个寄主因素。已经证明，它们中的一些可以被操纵来产生对目标病毒的遗传抗性。因此，更好地了解分子马铃薯Y病毒与寄主的相互作用可能会导致控制植物马铃薯Y病毒和其他植物病毒的新策略。在寻找宿主因子方面，在前一个资助周期中，我们利用基因芯片、酵母双杂交系统和表达序列标签等多种工具筛选出大约4000个宿主因子候选基因。这些候选基因包括编码病毒基因组翻译所需的翻译起始因子的基因，可能参与病毒RNA复制、组装和运输的RNA解旋酶蛋白，以及可能对病毒复制复合体的细胞内运输至关重要的囊泡运输蛋白。这一建议将有助于确定马铃薯Y病毒感染所需的这三个重要基因组中的基因，并进一步确定它们在病毒复制复合体的形成、功能和运输中的作用。因此，这一建议将增进我们对病毒复制机制的了解。预计这项研究中产生的新知识将有助于开发新的抗病毒策略。

Plant viruses are obligate intracellular parasites that infect many major crops and cause yearly losses over multibillion dollars in the world. Potyviruses constitute the largest group of plant viruses, including approximately 30% of all known plant viruses. Some of the most agriculturally important potyviruses include Turnip mosaic virus (TuMV), Clover yellow vein virus (ClYVV), Plum pox virus (PPV), Soybean mosaic virus (SMV), Potato virus Y (PVY), and Tobacco etch virus (TEV). One of the common properties shared by plant potyviruses and other plant viruses is their relatively small genome with a very limited protein-coding capacity. Thus, these viral pathogens must interact with host cells to recruit an array of host proteins (host factors) and metabolites to fulfill their life cycles. Recent studies on virus-plant interactions have identified several host factors. It has been shown that some of them can be manipulated to generate genetic resistance against target viruses. Thus, a better understanding of molecular potyvirus-host interactions may result in new strategies to control plant potyviruses as well as other plant viruses. In search for host factors, in the previous funding cycle, we have screened out approximately 4000 host factor gene candidates using diverse tools such as microarray, yeast two-hybrid system, and expressed sequence tags. These candidate genes include genes coding for translation initiation factors that may be required for viral genome translation, RNA helicase proteins that may participate in viral RNA replication, assembly and transport, and vesicular transport proteins that may be essential for the intracellular trafficking of virus replication complexes. This proposal will enable the identification of genes in these three important gene groups required in potyviral infection, and further characterization of their roles in the formation, function and trafficking of the virus replication complex. Therefore, this proposal will advance our knowledge of the virus replication mechanism. It is anticipated that the new knowledge generated in this study will contribute to the development of novel antiviral strategies.