5株H9N2亚型禽流感病毒HA、NA基因的序列分析

HA and NA gene sequence analysis of five H9N2 subtype avian influenza viruses

为了从分子生物学角度了解H9N2亚型禽流感病毒(AIV)在广西的遗传变异情况,对5株不同年代的广西H9N2亚型AIV的HA和NA基因进行克隆测序及同源性、遗传进化分析。结果表明,5株分离株均为低致病性AIV(LPAIV),HA、NA基因均属于欧亚谱系中的DK/HK/Y280/97(第I亚群),与我国代表株CK/BJ/1/94HA基因核苷酸、氨基酸同源性为93.5%～95.9%,NA基因核苷酸、氨基酸同源性为93.8%～95.8%。分离株DK/GX/51/05、CK/GX/55/05HA基因第226位氨基酸由谷氨酰胺(Gln)突变为亮氨酸(Leu),具备人类流感病毒的受体特征,而在糖基化位点方面,除了CK/GX/6/00HA基因的第218位发生变异以外,5株分离株HA基因上其余各糖基化位点均未发生变异;分离株DK/GX/51/05、CK/GX/55/05、QA/GX/B1/06NA基因均缺失第63、64、65位3个氨基酸,导致1个糖基化位点缺失,而CK/GX/6/00、WB/GX/A1/06NA基因则未发生缺失。

The present experiment was conducted to study the genetic variation amongst five H9N2 subtype avian influenza viruses in Guangxi,the HA and NA genes of these strains,which were isolated from samples collected in Guangxi during recent years,were amplified,cloned and sequenced.The sequence analysis showed that all five isolates were lower pathogenic avian influenza virus,and their HA and NA genes belonged to the DK/HK/Y280/97（I subgroup） of Eurasian lineage,and had 93.5-95.9% and 93.8-95.8% of nucleotide and animo acid homology to the HA and NA gene of Chinese representative strain CK/BJ/1/94,respectively.The glutamine at 226^th animo acid in HA gene of strains DK/GX/51/05 and CK/GX/55/05 was mutated to leucine,which had receptor characteristics of human influenza virus.While the glycosylation locus in HA genes of five strains had no mutation except for 218^th locus.All NA genes of DK/GX/51/05,CK/GX/55/05 and QA/GX/B1/06 were found to lack 63^th,64^th and 65^th animo acids,which resulted in deletion of one glycosylation locus,while those in CK/GX/6/00 and WB/GX/A1/06 were found to be normal.