Mucosal innate immune defense to Rift Valley fever virus

描述（由申请方提供）：本研究将确定粘膜毒力和先天免疫宿主防御气溶胶裂谷热病毒（A类生物防御病原体）的机制。裂谷热病毒（RVFV）被指定为优先病原体，这是基于其在故意释放的情况下对北美公共卫生和农业的严重影响。人类可通过蚊虫叮咬、食物污染或在接触RVFV感染牲畜体液期间吸入气雾剂传播。传播途径是否决定了人类裂谷热的严重程度尚不明确，也不知道在动物流行病中哪种途径最重要。人类裂谷热最常见的表现是一种急性自限性发热性疾病，但也可导致脑炎、视网膜炎和出血热。当出血性疾病发生时，通常在发病第3天开始;这种严重疾病的急性发作表明先天免疫在确定人类裂谷热疾病表现方面发挥重要作用。对保护性免疫至关重要的雾化RVFV感染和粘膜免疫的机制知之甚少。在人类感染中，I型IFN产生的延迟发作与RVFV诱导的临床疾病的更严重形式相关。Toll样受体（TLR）和RNA解旋酶家族的成员是能够检测病毒病原体相关分子模式（PAMP）的种系编码的模式识别受体（PRR）。当被激活时，PRR会刺激I型IFN和其他炎症细胞因子反应，以控制病毒复制和疾病。我们建议定义RVFV毒力和先天性免疫反应在不同的粘膜细胞类型假设是至关重要的主机防御雾化RVFV。因此，我们将开发雾化RVFV感染的体外人和鼠模型，以确定先天PRR在粘膜反应和临床疾病发病机制中的作用。我们假设I型IFN对RVFV感染口腔和肺粘膜的反应是受感染的上皮细胞和局部免疫细胞的先天性PRRs所指导的，并且这种反应的强度和持续时间取决于病毒剂量、粘膜细胞的容许性和免疫细胞迁移。具体而言，我们的目标是定义先天性免疫RVFV感染在人类粘膜和定义的作用，非结构RVFV蛋白NS和NSm的感染和先天性免疫反应，利用雾化减毒RVFV感染的小鼠模型。我们提出了高度相关的研究，以确定先天性免疫受体和参与早期宿主防御裂谷热病毒的途径。裂谷热病毒（RVFV）是布尼亚病毒科的一种白蛉病毒，根据其在故意释放的情况下对北美公共卫生和农业的严重影响，被指定为A类生物防御病原体。人类可通过蚊虫叮咬、食物污染或吸入气雾剂传播。人类裂谷热最常见的表现是一种急性自限性发热性疾病，但也可导致脑炎、视网膜炎和出血热。我们的研究，以确定粘膜先天免疫反应RVFV是新的，相关的，并有可能扩大预防和治疗的选择。此外，我们开发的研究工具，包括小鼠吸入模型，将对通过呼吸道途径传播的病毒的研究具有更广泛的适用性。

DESCRIPTION (provided by applicant): This study will define mucosal virulence and mechanism of innate immune host defense against aerosolized Rift Valley fever virus, a Category A biodefense pathogen. Rift Valley Fever virus (RVFV) is designated a priority pathogen based upon its projected severe impact on public health and agriculture in North America in the event of a deliberate release. Transmission to humans can occur either by mosquito bite, food contamination or aerosol inhalation during exposure to body fluids of RVFV-infected livestock. Whether the transmission route determines the severity of human RVF is not well defined, nor is it known which route is of primary importance during epizootics. Human RVF disease manifests most commonly as an acute self-limiting febrile illness, but can also lead to encephalitis, retinitis, and hemorrhagic fever. When hemorrhagic disease occurs, it usually begins on day 3 of illness; this acute onset of severe disease suggests an important role for innate immunity in defining human RVF disease manifestations. The mechanisms of aerosolized RVFV infection and mucosal immunity that are critical for protective immunity are poorly understood. In human infection, a delayed onset of type I IFN production is associated with the more severe forms of RVFV-induced clinical disease. Members of the Toll-like receptor (TLRs) and RNA helicase families are germ-line encoded pattern-recognition receptors (PRRs) capable of detecting viral pathogen associated molecular patterns (PAMPs). When activated, PRRs stimulate type I IFN and other inflammatory cytokine responses to control viral replication and disease. We propose to define RVFV virulence and innate immune responses in different mucosal cell types hypothesized to be critical for host defense against aerosolized RVFV. Therefore, we will develop in vitro human and murine models of aerosolized RVFV infection to define the role of innate PRRs in mucosal responses and clinical disease pathogenesis. We hypothesize that type I IFN responses to RVFV infection in the oral and pulmonary mucosa is directed by innate PRRs of infected epithelial cells and localized immune cells, and that the intensity and duration of this response is dependent on viral dose, mucosal cell permissiveness and immune cell migration. Specifically, we aim to define innate immunity to RVFV infection in human mucosa and to define the role of nonstructural RVFV proteins NSs and NSm in infection and the innate immune response utilizing a murine model of aerosolized attenuated RVFV infection. We proposed highly relevant studies to define the innate immune receptors and pathways involved in early host defense against Rift Valley fever Virus. Rift Valley Fever virus (RVFV), a Phlebovirus in the Bunyaviridae family, is designated a Category A biodefense pathogen based upon its projected severe impact on public health and agriculture in North America in the event of a deliberate release. Transmission to humans can occur either by mosquito bite, food contamination or aerosol inhalation. Human RVF disease manifests most commonly as an acute self-limiting febrile illness, but can also lead to encephalitis, retinitis, and hemorrhagic fever. Our studies to define mucosal innate immune responses to RVFV are novel, relevant and have potential to expand prevention and treatment options. Additionally, the research tools that we develop, including a murine inhalation model will have wider applicability to the study of viruses transmitted via a respiratory route.