Host Determinants of Human Metapneumovirus Immunity and Pathogenesis

描述（由申请人提供）：人偏肺病毒（hMPV）是最近发现的一种副粘病毒，是下呼吸道感染的主要原因。hMPV在儿童和成人中引起重复感染，在老年患者和有基础疾病的个人中引起严重疾病。hMPV的免疫机制和发病机制尚不清楚，也没有获得许可的疫苗或治疗方法。现有的有限信息表明，hMPV与其他副粘病毒（包括呼吸道合胞病毒）之间存在根本差异。因此，本研究的中心目标是阐明对hMPV的免疫机制，并确定宿主对疾病的免疫反应的贡献。我们提出三个互补的具体目的来阐明hMPV免疫机制和发病机制。在特异性目标1中，抗体在保护和疾病中的作用将被定义。B细胞缺陷小鼠将感染hMPV，并在继发感染后评估病毒生长和肺部病理。被动血清转移实验将确定是否需要抗体进行保护。抗体依赖性细胞毒性在免疫和疾病中的作用将用NK细胞缺陷小鼠来确定。在特异性目标2中，将确定hMPV融合(F)蛋白介导抗再感染保护的能力。用F蛋白免疫小鼠，并用编码不同F蛋白的工程病毒攻击小鼠。免疫和挑战小鼠将评估呼吸疾病和异常免疫反应。这些实验将验证以下假设：hMPV F蛋白疫苗与疾病增强无关，以及hMPV F蛋白能够诱导广泛的保护性免疫。在特异性目标3中，将定义T细胞对hMPV免疫和发病机制的贡献。幼稚T细胞缺陷小鼠将感染hMPV，并评估病毒复制和肺部病理。将T细胞缺陷小鼠接种hMPV，清除感染，并重新挑战以确定T细胞对继发性感染和肺部病理的保护作用。CTL表位疫苗接种和克隆的MHC i类限制性表位特异性CD8+ T细胞系的过继转移将用于确定病毒特异性CD8+ T细胞是否有助于病理。实验结果提出在这个应用程序将揭示宿主免疫可以导致感染和免疫发病机制的解决机制。这些发现将促进对hMPV免疫病理学的认识，指导hMPV疗法和疫苗的开发，并对其他呼吸道病毒具有广泛的适用性。

DESCRIPTION (provided by applicant): Human metapneumovirus (hMPV) is a recently discovered paramyxovirus that is a major cause of lower respiratory tract infection. hMPV causes repeat infections in children and adults and severe disease in older patients and individuals with underlying medical conditions. Mechanisms of hMPV immunity and pathogenesis are poorly understood and there are no licensed vaccines or therapeutics. The limited information available indicates that there are fundamental differences between hMPV and other paramyxoviruses, including respiratory syncytial virus. Accordingly, the central objective of the proposed research is to elucidate mechanisms of immunity to hMPV and define the contribution of host immune responses to disease. We propose three complementary specific aims to elucidate mechanisms of hMPV immunity and pathogenesis. In Specific Aim 1, the role of antibody in protection and disease will be defined. B cell-deficient mice will be infected with hMPV and viral growth and lung pathology assessed following secondary infection. Passive serum transfer experiments will determine whether antibody is required for protection. The role of antibody- dependent cellular cytotoxicity in immunity and disease will be determined using NK cell-deficient mice. In Specific Aim 2, the capacity of hMPV fusion (F) protein to mediate protection against reinfection will be determined. Mice will be immunized with F protein and challenged with engineered viruses encoding divergent F proteins. Immunized and challenged mice will be evaluated for respiratory disease and aberrant immune responses. These experiments will test the hypotheses that hMPV F protein vaccines will not be associated with enhanced disease and that hMPV F protein is capable of inducing broadly protective immunity. In Specific Aim 3, the contribution of T cells to hMPV immunity and pathogenesis will be defined. Naive T cell-deficient mice will be infected with hMPV, and viral replication and lung pathology will be assessed. T-cell-deficient mice will be inoculated with hMPV, allowed to clear infection, and rechallenged to determine the contribution of T cells to protection against secondary infection and lung pathology. CTL epitope vaccination and adoptive transfer of cloned MHC class I-restricted epitope-specific CD8+ T cell lines will be used to determine whether virus-specific CD8+ T cells contribute to pathology. Results of the experiments proposed in this application will reveal mechanisms by which host immunity can lead to both resolution of infection and immunopathogenesis. These findings will advance knowledge of hMPV immunopathology, guide the development of hMPV therapeutics and vaccines, and have broad applicability to other respiratory viruses.