REGULATION OF INFLUENZA VIRUS INFECTION BY ISG15

描述（由申请人提供）：最近爆发的高致病性流感病毒突出表明需要更好地了解流感病毒与其宿主之间的相互作用。病毒感染触发迅速的抗病毒反应，I型干扰素（IFN）通过上调大量IFN刺激基因（isg）在协调宿主反应中发挥核心作用。一些isg具有直接抗病毒活性，而其他isg通过调节免疫系统影响抗病毒反应。我们最近发现其中一个isg， ISG15，作为IFN诱导的关键抗病毒分子发挥作用。ISG15是一种泛素同源物，受干扰素、toll受体连接和病毒感染的强烈上调。ISG15缺陷小鼠在感染多种病毒（包括甲型和乙型流感病毒）后显示出更高的致死率。然而，ISG15发挥这种抗病毒活性的机制尚不清楚。ISG15结合广泛的细胞内蛋白，靶向许多生物过程。人体ISG15也从细胞中释放出来，作为细胞因子，激活各种免疫细胞。在本提案中，我们将验证ISG15与靶蛋白结合导致呼吸道上皮内病毒复制抑制并允许宿主随后清除病毒的假设。我们将用以下两个目标来检验这一假设。Aim 1的研究将探讨ISG15调控呼吸道上皮内病毒复制的机制。我们还将确定ISG15在这种细胞类型中的表达是否足以控制流感病毒感染。Aim 2的研究将确定ISG15的抗病毒活性是否需要偶联。我们将确定ISG15是否与病毒蛋白结合并调节病毒复制。从这些研究中获得的结果将为新发现的抗病毒分子ISG15的潜在作用机制提供重要见解。ISG15是一种关键的抗病毒分子，对包括甲型和乙型流感病毒在内的几种人类病原体具有活性。本课题拟通过研究其在流感病毒感染过程中的作用及偶联蛋白的需要来探讨其作用机制。这些研究可能为对抗病毒感染提供潜在的新治疗靶点。公共卫生相关性：ISG15是一种关键的抗病毒分子，对包括甲型和乙型流感病毒在内的几种人类病原体具有活性。本课题拟通过研究其在流感病毒感染过程中的作用及偶联蛋白的需要来探讨其作用机制。这些研究可能为对抗病毒感染提供潜在的新治疗靶点。

DESCRIPTION (provided by applicant): Recent outbreaks of highly pathogenic influenza virus have highlighted the need for a better understanding of the interactions between influenza virus and its host. Viral infection triggers a prompt anti-viral response, with type I interferons (IFNs) playing the central role in coordinating the host response through the upregulation of a large number of IFN stimulated genes (ISGs). Several ISGs have direct antiviral activity, while others impact upon the antiviral response by modulating the immune system. We have recently shown that one of these ISGs, ISG15, functions as a critical IFN induced anti-viral molecule. ISG15 is an ubiquitin homolog that is strongly upregulated by IFNs, toll receptor ligation, and viral infection. ISG15 deficient mice display increased lethality following infection with several viruses, including both influenza A and B viruses. Yet the mechanism by which ISG15 exerts this antiviral activity is unknown. ISG15 conjugates to a wide array of intracellular proteins, targeting numerous biological processes. Human ISG15 is also released from cells and functions as a cytokine, activating various immune cells. In this proposal we will test the hypothesis that the conjugation of ISG15 to target proteins results in the inhibition of viral replication within the respiratory epithelium and allows for subsequent clearance of the virus by the host. We will test this hypothesis with the following two aims. The studies in Aim 1 will explore the mechanism by which ISG15 regulates viral replication within the respiratory epithelium. We will also determine if expression of ISG15 within this cell type is sufficient to control influenza virus infection. The studies in Aim 2 will determine if conjugation of ISG15 is required for the antiviral activity of ISG15. We will determine if ISG15 conjugates to viral proteins and regulates viral replication. The results obtained from these studies will provide important insight into a potential mechanism of action for a newly identified antiviral molecule, ISG15. ISG15 functions as a critical antiviral molecule, with activity against several human pathogens, including both influenza A and B viruses. This proposal will explore its mechanism of action during influenza virus infection by investigating its sight of action and requirement for conjugation to target proteins. These studies may provide insight into a potential new therapeutic target in the fight against viral infections. PUBLIC HEALTH RELEVANCE: ISG15 functions as a critical antiviral molecule, with activity against several human pathogens, including both influenza A and B viruses. This proposal will explore its mechanism of action during influenza virus infection by investigating its sight of action and requirement for conjugation to target proteins. These studies may provide insight into a potential new therapeutic target in the fight against viral infections.