新城疫病毒（NDV）野毒株发生遗传变异可增强毒力并扩大宿主范围。前期研究发现基因III型毒力增强株，其HN基因所介导的免疫器官损伤是鸡致死的关键机制。但HN发挥该功能潜在的宿主机制还不清楚。本研究旨在探索病毒感染时与HN互作的宿主蛋白及靶细胞和靶分子，并阐明致病机理的生物学意义。研究内容包括：1)测定病毒亲和力、促融合和NA活性；2)体内感染外周血单个核细胞（PBMC），流式细胞术（FCM）分析细胞动态变化和细胞因子转录水平；3)口鼻或静脉接种途径感染鸡，分析PBMC细胞表型、细胞因子转录，免疫器官中自噬的产生与病毒复制、细胞因子转录水平；4)利用LC-MS/MS全面筛选与HN互作的宿主蛋白，IPA进行生物信息学分析，用Co-IP、GST-pull down和激光共聚焦技术对互作验证；5)对病毒激活宿主细胞、互作的宿主蛋白生物学学意义进行分析，研究将为NDV致病差异机制提供理论依据。

Field strains of Newcastle Disease virus (NDV), which undergo genetic mutation on viral genes, often increase the virulence and extend its host range. Therefore, it is crucial to explore the molecular basis and host mechanism for increased virulence of NDV. Our previous study demonstrated that velogenic genotype III NDV HN-mediated immune damage in chicken by intravenous inoculation (i.v.) contribute to the high mortality in SPF chickens. However, it is unclear which host factor contribute to HN-mediated the increased virulence of NDV. In this study, to further understand the pathogenesis of NDV HN genen, we will identify target cells and cytokine, and host protein interacted with HN. The following experiments will be performed. First, we will test binding affinity, fusion promotion and NA activity of HN protein of model virus. Second, we will explore the mechanisms of the cell activation and cytokines secretion of peripheral blood mononuclear cell (PBMC) in vitro separated from SPF chicken using flow cytometry and RRT-PCR. Third, we explore the mechanisms of the cell activation, cytokines secretion, autophagy and viral replication in PBMC separated from SPF chicken infected with NDV i.v or oro-nasal. Fourth, cellular proteins interacting with HN will be identified by LC-MS/MS and analyzed by bioinformatics software, and the interaction of the cellular protein and HN proteins will be confirmed by GST-pull down, co-immunoprecipitation and confocal microscopy assays. It will be carried out to identify the molecular mechanism of activation in targeted cells and factors, and biological significance of crucial mutation in HN on the increased virulence. This study may provide evidence of molecular mechanisms of different pathogenesis of NDV.