Virus-host interactions in the assembly of positive-strand RNA virus replication complexes

正链RNA病毒是7种病毒中最大的一类，包括许多重要的人类和动物病原体以及绝大多数植物病毒。一些例子包括寨卡病毒、丙型肝炎病毒、口蹄疫病毒和黄瓜花叶病毒。尽管感染非常不同的宿主并引起不同的症状，但这类病毒使用相似的策略复制其基因组RNA。作为一个不可或缺的过程，病毒复制也代表了开发抗病毒策略的一个很好的目标，这些策略应该提供强大的保护并适用于广泛的重要病毒病原体。该项目旨在表征病毒复制蛋白和某些宿主蛋白对病毒复制的贡献，预计将为病毒复制所需的机制以及病毒控制的新方法提供新的见解。该项目还有望为来自代表性不足群体的本科生提供转化植物科学的宝贵经验，并激励他们寻求更多的研究机会，并参加植物科学领域的研究生院。 正链RNA病毒复制的一个高度保守的特征是这些病毒重塑宿主细胞内膜以形成其病毒复制复合物（VRC），这是病毒复制的一个重要步骤。尽管其至关重要，膜重塑的机制，VRC内的脂质微环境，以及这些过程所需的宿主蛋白质知之甚少。该项目旨在通过使用雀麦花叶病毒（BMV）来填补上述知识空白，BMV是用于研究正链RNA病毒共有特征的模型病毒。BMV使外核膜内陷形成球状VRC。研究人员此前曾证明，一组病毒可以促进宿主在病毒复制位点合成磷脂酰胆碱，以支持病毒复制。特别是，BMV复制蛋白1a与VRC相互作用并招募磷脂酰胆碱生物合成酶。通过破坏特异性蛋白质-蛋白质相互作用来阻断酶的募集，以实现病毒抗性而不影响宿主脂质合成。由于宿主细胞内膜的脂质组成是动态的和复杂的，因此已经开发了体外测定来检查BMV复制蛋白1a和类似的病毒复制蛋白如何产生具有限定脂质组成的脂质体的膜内陷。此外，已发现宿主蛋白Erv 14是BMV复制所需的。Erv 14参与BMV VRC组装的机制以及Erv 14可能参与其他植物病毒的复制将被确定。

Positive-strand RNA viruses are the largest among 7 viral classes, including many important human and animal pathogens as well as the great majority of plant viruses. Some examples include Zika virus, hepatitis C virus, foot and mouth disease virus, and cucumber mosaic virus. Despite infecting very different hosts and causing distinct symptoms, viruses in this class use similar strategies to replicate their genomic RNAs. As an indispensable process, viral replication also represents an excellent target for the development of antiviral strategies that should provide strong protection and apply to a wide range of important viral pathogens. This project aims to characterize the contributions of viral replication proteins and certain host proteins to viral replication and is expected to provide new insights on mechanisms required for viral replication as well as novel approaches for virus control. The project is also expected to provide undergraduate students from underrepresented groups with valuable experience in translational plant science and inspire them to seek more research opportunities and attend graduate schools in the field of plant science. A highly conserved feature of positive-strand RNA virus replication is that these viruses remodel host intracellular membranes to form their viral replication complexes (VRCs), an essential step in viral replication. Despite its critical importance, the mechanisms by which membranes are remodeled, the lipid microenvironment within VRCs, and the host proteins required for such processes are poorly understood. This project aims to address aforementioned knowledge gaps by using brome mosaic virus (BMV), a model virus used to study the common features shared by positive-strand RNA viruses. BMV invaginates the outer nuclear membrane to form spherular VRCs. The investigators had previously demonstrated that a group of viruses promote host phosphatidylcholine synthesis at the viral replication sites for supporting viral replication. In particular, BMV replication protein 1a interacts with and recruits an enzyme of phosphatidylcholine biosynthesis to the VRCs. The recruitment of the enzyme will be blocked by disrupting the specific protein-protein interactions to achieve virus resistance without affecting host lipid synthesis. Because the lipid composition of host intracellular membranes is dynamic and complicated, an in vitro assay has been developed to examine how BMV replication protein 1a and similar viral replication proteins generate membrane invaginations of liposomes with defined lipid compositions. In addition, host protein Erv14 has been found to be required for BMV replication. The mechanism whereby Erv14 is involved in BMV VRC assembly and the possible involvement of Erv14 in the replication of other plant viruses will be determined.