1株广西鸡H_9亚型禽流感病毒的分离鉴定和HA基因分析

Identification and HA Gene Analysis of H_9 Subtype Avian Influenza Virus Isolated from Broiler from Guangxi

从广西某鸡场的发病鸡群中采样病料,接种10日龄SPF鸡胚后分离得到1株病毒,并命名为GL株,经微量血凝和微量血凝抑制检验为H9亚型禽流感病毒。测序结果分析显示,HA蛋白裂解位点的氨基酸序列为RSSR↓GLF,与低致病性禽流感病毒的基序一致。HA基因分型结果表明,GL株属于4.2.5分支。BLAST结果显示,HA基因序列与BJ0309株相似性最高,达99%。相似性比较结果表明,HA基因、蛋白与近年来国内流行的GX55等4.2.5分支H9亚型禽流感病毒相似性较高,分别为94.1%-98.8%和96.4%-99.3%,而与国内常用疫苗株SS、F、SD696等4.2.3分支H9亚型禽流感病毒相似性较低,分别为88.8%-89.8%和91.2%-92%。由此可见,分离的GL株属于4.2.5分支,与近年来国内流行株类似,并与常用疫苗株存在了一定的差异。

Samples from sick broilers from Guangxi province, were inoculated with 10 day-old chicken embryos. A virus,named GL was isolated. HA and HI tests result showed it was H9 subtype avian influenza virus positive. The result of sequence analysis showed that the amino-acid sequence of the haemagglutinin protein cleavage site was RSSR GLF, a typical sequence of LPAIV strains. Phylogenetic analysis showed that the strain of H9 hypotype AIV belonged to gene clade 4.2.5. The result of BLAST showed that HA gene nucleotides of the isolate were highest identities with B J0309 HgN2 isolate, with 99% identity. And the homology analysis of HA gene nucleotides and protein amino acids showed that the isolate was high identities with the prevalent strains, such as GX55, with 90.90/~97% and 93.4%-99.5%, respectively, but low identities with the common vaccine strains, such as SS, F and SD696, only with 85.8%-88.1% and 88.4%-89.1%, Respectively. As a result, the isolate belonged to gene clade 4.2.5, similar to the prevalent strains, which differed from the common vaccine strains belonged to gene clade 4.2.3.