Pathogenesis of Avian Influenza H7N1 and H7N7 Viruses in Poultry: Virulence Determinants, Adaptation and Within-Host Infection Dynamics of Low and High Pathogenicity Viruses

禽流感病毒（Avian influenza virus，AIV）属于正粘病毒科（Orthomyxoviridae）中的甲型流感病毒属（Influenza A Virus）。它们含有一个单链核糖核酸（RNA）基因组，由8个基因片段组成，编码至少11种病毒蛋白。根据其表面糖蛋白的抗原性变异，鉴定出16种HA（H1 - H16）和9种NA（N1 - N9）亚型。虽然所有亚型的AIV都会在家禽中引起轻微疾病（如果有的话），但H5和H7亚型的毒力差异很大，从无症状感染到高度致命感染。主要的爆发是由高致病性（HP）亚型引起的，这些亚型是在家养鸟类中传播后从低致病性（LP）祖先进化而来的。AIV的毒力标记是多基因的，其延伸至HA蛋白酶切位点之外。在过去二十年中，欧洲报告了由AIV H7亚型引起的毁灭性疫情。本项目将对部分H7 N1和H7 N7亚型禽流感病毒在不同禽类中的毒力和致病性进行研究。

Avian influenza viruses (AIV) belong to the genus Influenza A Virus in the family Orthomyxoviridae. They contain a single-stranded ribonucleic acid (RNA) genome composed of eight gene segments encoding at least 11 viral proteins. According to the antigenic variation of the surface glycoproteins the hemagglutinin (HA) and neuraminidase (NA), 16 HA (H1 - H16) and 9 NA (N1 – N9) subtypes have been identified. While AIV of all subtypes induce mild illness, if any, in poultry, virulence of H5 and H7 subtypes varies widely ranging from asymptomatic to highly lethal infections. Major outbreaks were caused by highly pathogenic (HP) subtypes which evolved from low pathogenic (LP) ancestors after circulation in domesticated birds. Virulence markers of AIV is multigenic exist which extend beyond the HA proteolytic cleavage site. During the last two decades, devastating outbreaks caused by AIV H7 subtypes have been reported in Europe. In this project, virulence determinates and pathogenesis of some H7N1 and H7N7 will be determined in different poultry species.