为阐明上海地区H9N2亚型禽流感病毒分离株的遗传变异、分子特征和重组模式，选取2002和2006～2014年分离自活禽市场、家禽养殖场和生猪屠宰场的14株H9N2亚型禽流感病毒进行分析。这14株病毒分别来源于鸡、鸭、鸽、野鸡咽喉和泄殖腔样品及猪肺脏样品，用H9亚型荧光反转录－聚合酶链反应(RT－PCR)试剂盒检测后，阳性样品经无特定病原体(SPF)级鸡胚尿囊腔接种并分离病毒，用血凝抑制(HI)实验进一步确定其血凝素(HA)亚型。RT－PCR分别扩增这14株病毒全基因并进行序列测定，分析8个基因片段的遗传发生关系，发现这些分离株主要由F/98亚系、Y280亚系、G1亚系及未知亚系重组而成。根据8个基因片段的组合情况，这14株病毒可分成5个基因型。2002、2006～2008年分离的5株H9N2亚型禽流感病毒代表了4个不同基因型，2009～2014年分离的9株H9N2亚型禽流感病毒属第5种基因型，推测可能与疫苗免疫选择压力有关。因此，在以后工作中加强H9N2亚型禽流感分子流行病学监测是非常必要的。

In order to explore the genetic variation and molecular characteristics of H9N2 subtype avian influenza viruses in Shanghai, fourteen H9N2 subtype avian influenza viruses were isolated from live poultry markets, poultry farms and pig slaughterhouses in 2002 and 2006－2014. These specimens included paired tracheal and cloacal swabs from chickens, ducks, pigeons and domestic wild chickens and lung samples from pigs. They were determined as H9 subtype by real－time reverse transcriptase－polymerase chain reaction (RT－PCR) and then isolated by using 10－day－old specific pathogen free chicken eggs, further identified as H9 subtype by hemagglutination inhibition (HI) test. The eight gene segments of the fourteen virus strains were amplified by RT－PCR and sequenced. Phylogenetic analysis revealed that the isolates were reassortants mainly of A/chicken/Shanghai/F/1998, A/duck/HongKong/Y280/1997, A/quail/ HongKong/G1/1997. Five virus strains isolated from 2002 and 2006－2008 represented four different genotypes. The other nine virus strains isolated in 2008－2014 was different from the above four genotypes. This may be related to the pressure of immune selection by vaccine.