Clade7.2 H5N1亚型禽流感病毒（Avian influenza virus, AIV）于2006年首次在我国北方地区监测到。2012年我们再次监测到该类型病毒，发现其抗原性发生明显变异。本项目拟开展Clade7.2病毒抗原性变异的分子基础研究，系统分析监测到的Clade7.2 H5N1亚型AIV抗原性变异情况，选择抗原性存在明显差异的一对株AIV，采用经典的禽流感反向遗传操作系统，构建一系列HA基因抗原区域互换和点突变重组病毒，并通过血凝抑制试验、微量中和试验和疫苗攻毒试验进行验证，确定影响AIV抗原性的关键抗原区域和氨基酸位点；与监测到的其他H5N1 AIV 分离株进行比对，验证氨基酸特征的普遍性。项目完成所阐明的决定Clade7.2 AIV抗原性的关键抗原区域或氨基酸位点，为监测H5N1亚型AIV的变异和新疫苗的研制提供重要科学依据。

H5N1 Clade7.2 avian influenza virus(AIV) was firstly isolated in North China in 2006 and reemerged in chickens in North China in 2012 and showed significant antigenic drift. To determine the molecular basis of antigenic drift of H5N1 viruses, the antigenicity of H5N1 viruses (clade 7.2) are systematically analysed to select two model viruses with distinct antigeniciy. A series of ressortant viruses are generated by reverse genetics to illuminate the key epitope and amino acids influencing the virus antigenicity by microneutralization and vaccine challenge test and analyse its influence to the virus antigenic conformation. We verify the universality of the key factor in other clade 7.2 viruses. This study will show regular pattern of the key epitope and amino acid influencing the virus antigenicity to provide more important information for monitoring AIV antigenic drift and new vaccine development in the future.