Host Determinants of Human Metapneumovirus Immunity and Pathogenesis

HMPV是全球儿童下呼吸道感染（LRI）的主要原因，仅次于呼吸道感染。 合胞病毒（RSV）。尽管几乎所有人在儿童时期都感染过HMPV，但对HMPV的免疫力仍然很低。 是不完全的，并且在整个生命中发生再感染。HMPV患者更有可能住院治疗， 基础疾病，如哮喘、慢性阻塞性肺病、HIV或早产。有 没有批准的抗病毒治疗或疫苗。HMPV的宿主或病毒毒力决定因素尚不清楚。 许多先前研究的一个局限性是大多数HMPV研究使用少数实验室适应菌株之一， 对小鼠造成轻微的疾病。我们已经确定了临床分离的HMPV，导致严重和致命的 疾病的小鼠，提供工具来阐明发病机制。初步数据显示， 强毒HMPV有效地诱导I型和III型干扰素（IFN），并且这些细胞因子表现出不一致的 角色IFN对启动和形成适应性免疫应答至关重要，但也可能导致疾病;我们的目标是 定义I型和III型IFN在HMPV中的作用。HMPV抑制I型IFN应答，包括STAT 1 和STAT 2磷酸化，HMPV缺乏副粘病毒V蛋白或 RSV的NS 1/NS 2。已经涉及几种HMPV蛋白，包括G、M2-1、P和SH。公布数据 来自我们小组和其他人的研究表明，SH介导免疫抑制，但机制或特定的SH宿主 蛋白质相互作用是未知的。其他HMPV蛋白对毒力的贡献尚未确定。 我们建议使用体外和体内方法来解决这些知识差距。在目标1中，我们定义 III型IFN（IFN-λ）对HMPV免疫和发病机制的贡献， 敲除小鼠目的2提出确定SH的细胞靶点，定义相互作用域，并发现 HMPV抑制天然免疫的分子机制。我们将使用瞬时转染标记的 突变SH蛋白和具有SH突变的病毒在细胞和小鼠实验中。在目标3中，将使用反向 在实验室中开发的遗传学，用于产生嵌合病毒并鉴定病毒毒力的蛋白质决定因素 使用已建立的小鼠模型。我们的初步数据表明IFN-λ在HMPV免疫中的重要作用， 证实HMPV SH的天然免疫抑制作用，并证明无毒力和毒力的强度 菌株，以确定毒力的病毒决定因素。拟议研究的结果将阐明机制 HMPV发病机制的研究，并为HMPV病毒感染的潜在治疗途径和策略提供了蓝图。 用于疫苗的减毒。这些发现可能与其他呼吸道病毒有关。

HMPV is a major cause of lower respiratory infection (LRI) in children worldwide, second only to respiratory syncytial virus (RSV). Although nearly all people are infected with HMPV during childhood, immunity to HMPV is incomplete and re-infections occur throughout life. Hospitalization with HMPV is more likely in persons with underlying conditions such as asthma, chronic obstructive pulmonary disease, HIV, or prematurity. There are no approved antiviral therapies or vaccines. Host or viral determinants of virulence are not known for HMPV. One limitation of many prior studies is that most HMPV research uses one of a few lab-adapted strains that cause minimal disease in mice. We have identified clinical isolates of HMPV that cause severe and fatal disease in mice, providing tools to elucidate mechanisms of pathogenesis. Our preliminary data show that virulent HMPV potently induces types I and III interferon (IFN), and that these cytokines exhibit discordant roles. IFN is critical to initiate and shape adaptive immune responses but can contribute to disease; we aim to define the contribution of types I and III IFN in HMPV. HMPV inhibits type I IFN responses including STAT1 and STAT2 phosphorylation by an unknown mechanism, and HMPV lacks the paramyxovirus V protein or NS1/NS2 of RSV. Several HMPV proteins have been implicated, including G, M2-1, P, and SH. Published data from our group and others suggest SH mediates immune inhibition but a mechanism or specific SH-host protein interaction is unknown. The contribution of other HMPV proteins to virulence has not been defined. We propose to use in vitro and in vivo approaches to address these knowledge gaps. In Aim 1, we will define the contributions of type III IFN (IFN-λ) to HMPV immunity and pathogenesis using global and conditional knockout mice. Aim 2 proposes to identify the cellular target(s) of SH, define interacting domains, and discover the molecular mechanisms of innate immune inhibition by HMPV. We will use transient transfection of tagged mutant SH proteins and viruses with SH mutations in cell and mouse experiments. In Aim 3, will use reverse genetics developed in the lab to generate chimeric viruses and identify viral protein determinants of virulence using established mouse models. Our preliminary data suggest an important role for IFN-λ in HMPV immunity, confirm innate immune inhibition by HMPV SH, and demonstrate the strength of the avirulent and virulent strains to identify viral determinants of virulence. The results of the proposed research will clarify mechanisms of HMPV pathogenesis and provide a blueprint for potential therapeutic avenues and strategies for viral attenuation for vaccines. The findings are likely to be relevant to other respiratory viruses.