H9N2亚型禽流感病毒基因组全长序列测定和各基因的遗传分析

用RTPCR技术及cDNA末端快速扩增法获得禽流感病毒分离株A/Chicken/Shanghai/F/98（H9N2）代表基因组全长的8个基因片段。基因组序列比较及遗传进化分析结果表明，Chicken/Shanghai/F/98的8个基因均不属于Quail/Hong Kong/G1/97亚系，与香港禽流感事件没有直接关系。它与Chicken/Beijing/1/94的HA、NA、M、NS基因同源率分别为96.7%、96.4%、97.5%和98.0%，这4个基因属于Chicken/Beijing/1/94亚系，其中，NA基因与Duck/Hong Kong/Y280/97的同源率为97.4%，而且它们均在205位后缺失9个核苷酸。而PB2、PB1、PA和NP基因与已知的3个亚系关系较远，分别在相应的进化树上另成分支。因此，Chicken/Shanghai/F/98是两个以上不同基因亚系间发生自然重排的产物。

Genetic Characterization of the Entire Genome of an H9N2 Avian Influenza Virus A/Chicken/Shanghai/F/98

Eight full-length genes of an H9N2 subtype avian influenza virus A/Chicken/Shanghai/F/98(H9N2), were amplified by RT-PCR and rapid amplification of cDNA ends (RACE) and sequenced. The results of phylogenetic analysis showed that A/Chicken/Shanghai/F/98 was entirely different from Quail/Hong Kong/G1/97 which was directly related to human infection with avian influenza virus in Hong Kong, whereas its HA, NA, M and NS genes belonged to A/Chicken/Beijing/1/94-like sublineage with the nucleotide homology of 96.7%, 96.4%, 97.5% and 98.0% respectively. The homology of NA gene between A/Chicken/Shanghai/F/98 and A/Duck/Hong Kong/Y280/97 was 97.4% and they both lost 9 nucleotides between nt 205 to 206. However, the PB2, PB1, PA, NP genes did not show any close relationship with those of the three known sublineages and the later three didn't share immediate ancestors with available isolates whose sequences had been reported. Therefore, A/Chicken/Shanghai/F/98 is a product of natural reassortment between H9N2 avian influenza viruses from different sublineages.