Influenza virus host shutoff mechanism

流感病毒宿主关闭机制

• 批准号: 9761968
• 负责人: TORU TAKIMOTO
• 金额: $ 38.5万
• 依托单位: UNIVERSITY OF ROCHESTER
• 依托单位国家: 美国
• 财政年份: 2017
• 资助国家: 美国
• 起止时间: 2017-09-25 至 2022-08-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/9761968
• 关键词: Affect; Antiviral Agents; Attention; Attenuated; Attenuated Live Virus Vaccine; Baculoviruses; Biological Assay; C-terminal; Cell Nucleus; Cells; Cleavage And Polyadenylation Specificity Factor; Cytoplasm; Data; Elements; Eukaryotic Initiation Factors; Foundations; Gene Expression; Growth; Host Defense Mechanism; Human; Immune Evasion; Immune response; In Vitro; Inflammation; Inflammatory; Influenza A Virus, H1N1 Subtype; Influenza A virus; Innate Immune Response; Integration Host Factors; Learning; Location; Lung; Mass Spectrum Analysis; Mediating; Messenger RNA; Molecular; Mutation; Nuclear Export; Open Reading Frames; Outcome; Pathogenicity; Play; Poly(A)-Binding Proteins; Polynucleotide Adenylyltransferase; Protein Analysis; Protein Biosynthesis; Proteins; RNA Polymerase II; Reporting; Research; Ribosomal Frameshifting; Ribosomes; Role; Safety; Site; System; Testing; Transcript; Translating; Translations; Vaccines; Viral; Viral Genes; Viral Proteins; Virus; Virus Diseases; Virus Replication; base; comparative; cytokine; endonuclease; improved; in vivo; influenzavirus; mRNA Precursor; mRNA Transcript Degradation; mouse model; mutant; novel; overexpression; pandemic disease; prevent; protective efficacy; protein expression; recombinant virus; response; vaccine efficacy

Virus infection induces a wide range of host defense mechanisms, such as the innate immune response and inflammation. Some viruses express accessory proteins to induce general shutoff of host protein synthesis, which is considered to be one of the major viral strategies to counteract host antiviral activity and immune response. Influenza A virus is one of these viruses and expresses two proteins NS1 and PA-X to induce host shutoff. PA-X is a novel protein found to be expressed from PA mRNA by ribosomal frameshifting. PA-X is composed of an endonuclease domain of PA with a unique C-terminal region. Recent studies including ours indicate that mRNA degradation is the major strategy for host shutoff. The PA-X is more active in shutoff activity than NS-1, and it contains multiple regions involved in specific mRNA degradation. Characterization of a mutant 2009 pandemic H1N1 virus expressing reduced amount of PA-X indicates that PA-X plays a significant role in antagonizing host innate and acquired immune responses. The mechanism of how PA-X induces shutoff is not known. However, a recent study showed that PA-X selectively degrades host RNA polymerase II transcripts, and that pre- mRNAs under 3’-processing are susceptible for PA-X degradation. We also found that PA-X localizes and degrades mRNAs in both the nucleus and cytoplasm, suggesting that PA-X has multiple strategies to capture and degrade pre-mRNAs and mature mRNAs in cells. This project will reveal the mechanism of how PA-X targets and degrades host pre-mRNA in the nucleus (Aim 1), and mature mRNAs in the cytoplasm (Aim 2). Using viruses having various shutoff activities, we will determine the functional interaction between PA-X and NS1 to unveil how IAV adjusts the level of shutoff to create optimum condition for viral replication. Because the shutoff activity directly affects host immune responses, we will test a hypothesis that efficacy of live attenuated vaccine can be improved by suppressing shutoff activity. Overall, the proposed study will provide a foundation for understanding 1) the mechanism by which influenza viruses modulate host gene expression, 2) the mechanism by which viral gene expression is optimized, and 3) the impact of PA-X on viral pathogenicity and host immune response. Upon completion of these studies, we will learn the unique multiple strategy of PA-X in inducing host shutoff in infected cells, and its impact on viral pathogenicity and immune evasion.

病毒感染诱导宿主广泛的防御机制，如先天免疫， 反应和炎症。一些病毒表达辅助蛋白以诱导宿主的全面关闭 蛋白质合成，这被认为是抵抗宿主抗病毒的主要病毒策略之一 活动和免疫反应。甲型流感病毒是这些病毒之一，表达两种蛋白质 NS 1和PA-X诱导宿主关闭。PA-X是一种新的蛋白质，它是由PA mRNA表达的， 核糖体移码PA-X由PA的核酸内切酶结构域组成，其具有独特的C-末端 地区包括我们在内的最新研究表明，mRNA的降解是宿主的主要策略， 关闭。PA-X比NS-1具有更强的封堵活性，并且它包含多个涉及的区域 在特定的mRNA降解中。表征突变的2009年大流行性H1N1病毒，其表达 PA-X的量减少表明PA-X在拮抗宿主先天性和 获得性免疫反应PA-X如何诱导关闭的机制尚不清楚。但 最近的研究表明，PA-X选择性地降解宿主RNA聚合酶II的转录本， 处于3 '-加工下的mRNA对PA-X降解敏感。我们还发现PA-X定位于 并降解细胞核和细胞质中的mRNA，这表明PA-X具有多种策略 捕获并降解细胞中的前mRNA和成熟mRNA。这个项目将揭示 PA-X如何靶向和降解细胞核中的宿主前mRNA（Aim 1），以及细胞核中的成熟mRNA。 细胞质（Aim 2）。使用具有各种关闭活动的病毒，我们将确定功能 PA-X和NS 1之间的相互作用，揭示了IAV如何调整关闭水平，以创造最佳的 病毒复制的条件。由于关闭活性直接影响宿主的免疫反应，我们 将检验一个假设，即减毒活疫苗的效力可以通过抑制关闭来提高 活动总的来说，拟议的研究将为理解1）机制提供基础， 流感病毒调节宿主基因表达的机制，2）病毒基因 PA-X对病毒致病性和宿主免疫应答的影响。 通过这些研究，我们将了解PA-X诱导宿主的独特多重策略 在感染细胞中的关闭，及其对病毒致病性和免疫逃避的影响。