Mechanism of IFIT-Mediated Antiviral Effects

 描述(申请人提供)：病毒感染会引起先天免疫和I型干扰素反应的激活，从而限制病毒的复制和传播。西尼罗河病毒(West Nile Virus，WNV)是一种新出现的蚊媒病原体，可引起多种脊椎动物的致死性脑炎。在大多数情况下，激活细胞内和细胞外的固有免疫反应可以控制病毒复制，防止脑炎和死亡。要了解西尼罗河病毒感染被先天免疫反应抑制的机制，需要了解感染诱导的先天免疫蛋白的抗病毒功能。在这项提案中，我们将表征一个进化保守的蛋白质家族的抗病毒作用，该家族被称为带有四肽重复序列的干扰素诱导蛋白(IFIT)。由于5‘端存在非典型的RNA修饰，iFit蛋白在先天免疫反应中被早期诱导并高水平表达，并已被证明识别病毒RNA为非我；然而，这种识别发生的机制以及单个IFIT蛋白在识别病毒RNA中的作用尚未确定。在这里，我们将使用基于生化和细胞培养的分析来确定IFIT蛋白与病毒RNA结合的能力，并确定RNA结合和识别如何抑制病毒复制。我们还将使用缺乏所有三个iFit基因的小鼠模型来评估IFIT抗病毒活性的组织和细胞类型特异性效应。我们假设IFIT蛋白的不同组合将不同地影响病毒复制，并且IFIT蛋白将显示特定于组织和细胞类型的优势。这项研究的结果可能支持使用来自多个家庭的对IFIT抗病毒活性高度敏感的病毒作为新型疫苗，并为开发使病毒对IFIT抗病毒作用敏感的新型抗病毒药物提供途径 IFit蛋白质。

 DESCRIPTION (provided by applicant): Viral infection induces the activation of the innate immune and Type I interferon responses, which act to restrict viral replication and spread. West Nile virus (WNV) is an emerging mosquito-borne pathogen that can cause fatal encephalitis in multiple vertebrate animal species. In the majority of cases, activation of the cell-intrinsic and cell-extrinsic innate immune responses controls viral replication and prevents encephalitis and death. Understanding the mechanisms by which WNV infection is inhibited by the innate immune response requires an understanding of the antiviral functions of innate immune proteins induced by infection. In this proposal, we will characterize the antiviral action of an evolutionarly conserved family of proteins termed interferon-induced protein with tetratricopeptide repeats (IFIT). IFIT proteins are induced early and to high levels during an innate immune response and have been shown to recognize viral RNA as non-self due to the presence of atypical RNA modifications at the 5' end; however, the mechanism by which this recognition occurs and the role of individual IFIT proteins in recognizing viral RNA has yet to be determined. Here, we will use biochemical and cell-culture based assays to determine the ability of IFIT proteins to bind viral RNA and determine how RNA binding and recognition inhibits viral replication. We also will use a mouse model lacking all three Ifit genes to assess tissue- and cell-type-specific effects of IFIT antiviral activity. We hypothesize that different combinations of IFIT proteins will differentially affect viral replication and that IFIT proteins will show a tissue- and cell type-specific dominance. The results of this study may support the use of viruses from multiple families that are highly susceptible to IFIT antiviral activity as novel vaccines and provide an avenue for development of novel antiviral agents that sensitize viruses to the antiviral effects of IFIT proteins.