中文摘要：

为掌握近年来H9亚型禽流感的流行状况和遗传变异规律，从河南、陕西发病养殖场采集病料，用鸡胚接种法分离病毒，并用RT—PCR法对分离出的H9N2 AIV的HA基因进行扩增、克隆、测序及对得到的序列进行同源性和遗传性分析。结果表明：获得了2株HgN2亚型流感病毒，这2株病毒HA基因变异程度不大，核苷酸序列和氨基酸同源性分别为97．1％和97．8％，均属于BJ/1／94分支（Y280小分支）。从分子水平分析，这2株病毒均属于低致病力的H9N2禽源流感病毒。

英文摘要：

This experiment was conducted to evaluate the epidemic regularity and molecular characterization variation of H9 subtype avian influenza in recent years. The epidemic materials were collected from diseased chicken farms in Henan and Shaanxi, the virus was isolated by inoculating chicken em bryos,and the HA gene of the isolates were amplified by RT-PCR and completely sequenced. We obtain two strains of subtype H9N2 influenza viruses, they belonged to BJ/1/94 branch （Y280 subbranch）, and their HA genes had little variation, its nucleotide sequence and amino acid homology were 97.1% and 97.8% respectively. By the molecular level analysis, these two strains of virus were low pathogenic force source of H9N2 avian influenza virus.