Investigating How ADP-ribosylation Impacts Innate Immunity During Coronavirus Infection

总结 冠状病毒（CoV）已被证明是兽医和医学重要的病原体 自50多年前发现以来，它们是最近两次流行病（SARS-CoV和MERS）的罪魁祸首， CoV）。冠状病毒建立感染和引起疾病的能力取决于它们抑制病毒的能力。 宿主先天免疫反应。在这一领域仍然存在许多问题，例如病毒因子在哪些方面起作用， 体内以防止细胞因子表达，以及除了MDA5之外的RNA传感器是否可以检测CoV RNA。我是 对探索阻断免疫反应的病毒因子以及促进免疫反应的宿主蛋白质感兴趣。 反应和介导的保护免受感染。我发现保守的冠状病毒 大结构域既抑制先天性免疫应答，又促进体内复制， 发病机制此外，我们的小组和其他人已经表明，CoV宏结构域是一种酶， 从蛋白质中去除ADP-核糖。这些研究表明，蛋白质ADP-核糖基化是一种机制， 以促进先天免疫反应。然而，无论是催化ADP的酶- 核糖基化（PARP）或这种修饰的靶标是已知的。本提案的核心目标 是为了确定介导抗病毒ADP-核糖基化的因素，并提高我们对 ADP核糖基化如何影响对抗CoV感染的先天免疫反应。目标1我会 筛选在CoV感染期间影响先天免疫的PARP并确定其定位。在 目的2，系统地确定在细胞内激活的信号通路的传感器和具体步骤， 没有macrodomain。利用这两个目标的结果，我将开始以下过程： 鉴定CoV宏结构域的直接蛋白质靶标。综合起来，这些目标将进一步确定如何 ADP-核糖基化影响先天免疫和CoV发病机制，并将解决如何 大结构域对抗细胞ADP-核糖基化，这在文献中仍然是一个显著的空白。详细 了解ADP-核糖基化和CoV宏结构域之间的相互作用将提供重要的见解 宿主反应的机制以及病毒如何对抗这种反应。

SUMMARY Coronaviruses (CoVs) have proven to be significant pathogens of both veterinary and medical importance since their discovery over 50 years ago and are responsible for two recent epidemics (SARS-CoV and MERS- CoV). The ability of CoVs to establish infection and to cause disease is dependent on their ability to inhibit the host innate immune response. Many questions still remain in this field, such as what viral factors function in vivo to prevent cytokine expression, and whether RNA sensors other than MDA5 can detect CoV RNA. I am interested in exploring both viral factors that block the immune response, as well as host proteins that promote the response and that mediate protection from infection. I have discovered that the conserved CoV macrodomain both suppresses the innate immune response and promotes in vivo replication to facilitate viral pathogenesis. Furthermore, our group and others have shown that the CoV macrodomain is an enzyme that removes ADP-ribose from proteins. These studies indicate that protein ADP-ribosylation is a mechanism used by the host to promote the innate immune response. However, neither the enzymes that catalyze the ADP- ribosylation (PARPs) or the targets of this modification are known. The central objectives in this proposal are to identify the factors that mediate antiviral ADP-ribosylation and enhance our understanding of how ADP-ribosylation impacts the innate immune response to counter CoV infection. In Aim 1 I will screen for the PARP(s) that impacts innate immunity during CoV infection and determine its localization. In Aim 2, I will systematically identify the sensor and specific step of the signaling pathway that is activated in the absence of the macrodomain. Utilizing the results from these two aims, I will then begin the process of identifying the direct protein target of the CoV macrodomain. Taken together, these aims will further define how ADP-ribosylation impacts innate immunity and CoV pathogenesis and will address the mechanism of how macrodomains combat cellular ADP-ribosylation, which remains a significant gap in the literature. A detailed understanding of the interplay between ADP-ribosylation and CoV macrodomains will provide significant insight into mechanisms of the host response and how viruses combat this response.