Structure-Function Analysis of Mxra8 Interaction with Alphaviruses.

项目总结/摘要 甲病毒是披膜病毒科的蚊子传播的正链包膜RNA病毒， 导致全球性的人类疾病。目前，没有抗病毒药物或许可的疫苗可用于治疗或 预防任何甲病毒感染。我们最近使用了一种基于CRISPR/Cas9的全基因组筛选， 细胞表面分子Mxra 8作为引起关节炎的多种新出现的甲病毒的新型进入受体 和肌肉骨骼疾病，包括基孔肯雅病（CHIKV）、罗斯河病（RRV）、马亚罗病（MAYV）和奥尼扬病（O 'nyong） Nyong（ONNV）病毒。小鼠Mxra 8或人MXRA 8的基因编辑导致甲病毒感染减少 的细胞，并且异位表达导致感染增加。Mxra 8与CHIKV直接结合 颗粒和增强的病毒附着和内化到细胞中。我们假设 不同甲病毒的mxra 8将解释感染、组织靶向和疾病发病机制如何发生。 Diamond、Fremont和Smit实验室之间的这一合作提案的主要目标是 为了定义Mxra 8促进甲病毒进入细胞的精确机制，以获得高- 解析Mxra 8如何接合甲病毒病毒粒子的结构洞察，并确定详细的 Mxra 8在多种致关节炎甲病毒急性和慢性感染中的作用 体内使用新的鼠模型。该提案中的实验将定义甲病毒的基本方面 生物学增强了我们对感染和细胞向性的理解。这些信息可能有助于 开发破坏Mxra 8与甲病毒刺突蛋白相互作用的小分子或生物制剂， 可以形成未来治疗的基础，改善多种新出现的甲病毒的疾病。

Project Summary/ Abstract Alphaviruses are mosquito-transmitted, positive-strand enveloped RNA viruses of the Togaviridae family that cause global disease in humans. At present, no antiviral agents or licensed vaccines exist for the treatment or prevention of any alphavirus infections. We recently used a genome-wide CRISPR/Cas9-based screen to identify the cell surface molecule Mxra8 as a novel entry receptor for multiple emerging alphaviruses that cause arthritis and musculoskeletal disease including chikungunya (CHIKV), Ross River (RRV), Mayaro, (MAYV), and O'nyong nyong (ONNV) viruses. Gene editing of mouse Mxra8 or human MXRA8 resulted in reduced alphavirus infection of cells, and reciprocally, ectopic expression resulted in increased infection. Mxra8 bound directly to CHIKV particles and enhanced virus attachment and internalization into cells. We hypothesize that engagement of Mxra8 by different alphaviruses will explain how infection, tissue targeting, and disease pathogenesis occurs. The primary goals of this collaborative proposal between the Diamond, Fremont, and Smit laboratories are to define the precise mechanism(s) by which Mxra8 facilitates alphavirus entry into cells, to gain high- resolution structural insight as to how Mxra8 engages the alphavirus virion, and to determine the detailed role of Mxra8 in the pathogenesis of acute and chronic infection of multiple arthritogenic alphaviruses in vivo using novel murine models. The experiments in this proposal will define fundamental aspects of alphavirus biology that enhance our understanding of infection and cell tropism. This information may facilitate the development of small molecules or biologicals that disrupt Mxra8 interaction with alphavirus spike proteins, which could form the basis of future therapeutics that ameliorate disease of multiple emerging alphaviruses.