Cellular targets of acute and chronic strains of MNV

项目摘要 诺如病毒（NV）是全球急性胃肠炎的主要原因，估计造成2.67亿人感染 感染和20万人死亡。限制NV疾病的努力受到了严重的阻碍， 抗原多样性和新菌株的频繁出现，使疫苗开发变得困难。最近它 已经认识到，NV在无症状个体中引起持续性感染，从而产生了一种 病毒传播和免疫驱动进化的储存库。NVs如何逃避宿主免疫并坚持 健康个体是未知的，并且是本申请的焦点。我们使用了小鼠NV（MNV）系统 研究CD 8 T细胞对急性清除（CW 3）与持续（CR 6）菌株的应答。MNV-CR 6持续存在， 即使在我们引入了增强其CD 8 T细胞免疫原性的突变之后， MNV-CR 6 F-γ）并导致大量MNV特异性CD 8 T细胞。这些MNV特异性CD 8 T细胞 没有内在缺陷并被运输到肠道，对离体肽刺激有反应， 在体内对MNV-CW 3的应答中增殖，但未能阻止慢性MNV-CR 6 F免疫应答的建立。 感染接下来，我们通过用MNV-CW 3初次感染免疫小鼠，并用MNV-CW 3攻击这些小鼠。 CR 6 F双头。免疫小鼠最初控制了MNV-CR 6 F病毒，然而在大多数情况下，病毒复制反弹， 建立了慢性感染。随后的过继转移实验表明，预先存在的MNV- 特异性CD 8 T细胞最初响应于MNV-CR 6 F γ的攻击，然而在72小时内变得 显然不知道病毒正在复制基于这些发现，我们假设慢性菌株 的MNV逃避适应性免疫反应，通过坚持在免疫豁免的细胞和/或 解剖生态位我们将通过使用创新的方法和新的分子工具来测试这一假设， MNV在感染的急性和慢性阶段的细胞靶点。此外，我们还打算 感染的细胞在其局部组织环境中，以了解关键的细胞相互作用， 确定MNV清除率与持久性。这些实验将提供重要的见解， 持久性和免疫逃避在粘膜网站，是一个直接延伸的K资助的研究进行 由申请人出。此外，这些实验将与未来的疫苗设计工作有关。是 预计这一R 03奖将大大促进PI的过渡到独立。

PROJECT SUMMARY Noroviruses (NV) are the leading cause of acute gastroenteritis globally, causing an estimated 267 million infections and 200,000 deaths each year. Efforts to limit NV disease have been hampered by significant antigenic diversity and frequent emergence of novel strains, making vaccine development difficult. Recently it has been appreciated that NVs cause persistent infections in asymptomatic individuals, thereby creating a reservoir for viral dissemination and immune-driven evolution. How NVs evade host immunity and persist in healthy individuals is unknown and is the focus of this application. We have used the mouse NV (MNV) system to study CD8 T cell responses to acutely-cleared (CW3) vs. persisting (CR6) strains. MNV-CR6 persisted after primary infection even after we introduced a mutation that enhanced its CD8 T cell immunogenicity (strain MNV-CR6FY) and resulted in large numbers of MNV-specific CD8 T cells. These MNV-specific CD8 T cells had no intrinsic defects and trafficked to the intestine, responded to ex vivo peptide stimulation, and proliferated in vivo in response to MNV-CW3, yet failed to prevent establishment of chronic MNV-CR6FY infection. Next we immunized mice via primary infection with MNV-CW3 and challenged these mice with MNV- CR6FY. Immune mice initially controlled MNV-CR6FY, however in most cases viral replication rebounded and chronic infection was established. Subsequent adoptive transfer experiments showed that pre-existing MNV- specific CD8 T cells initially respond to challenge with MNV-CR6FY, however within 72 hours become apparently ignorant of ongoing viral replication. Based in these findings we hypothesize that chronic strains of MNV evade adaptive immune responses by persisting in an immunoprivileged cellular and/or anatomic niche. We will test this hypothesis by using innovative methods and novel molecular tools to define the cellular targets of MNV during acute and chronic stages of infection. Furthermore, we intend to image infected cells within their local tissue environment to gain an understanding of key cellular interactions that determine MNV clearance vs. persistence. These experiments will provide important insights into viral persistence and immune evasion at mucosal sites and are a direct extension of the K-funded research carried out by the applicant. Moreover these experiments will be relevant to future vaccine design efforts. It is expected that this R03 award will greatly facilitate the PI's transition to independence.