不同年份2.3.4.4分支H5亚型禽流感病毒HA基因的序列分析

Sequence analysis of hemagglutinin gene of H5 subtype avian influenza virus of clade 2.3.4.4 in different years

H5亚型禽流感2.3.4.4分支病毒作为我国优势流行毒株已流行多年,流行毒株是否会因变异而导致免疫失败引起关注。本研究对2014-2017年流行毒株进行测序,比较分析了其抗原位点的变异情况,结果发现2017年的流行毒株已发生较大的变异,形成了一个独立的分支,与其之前的毒株HA核苷酸序列的差异达4.4%-5.4%。其最大特征是HA蛋白的142位E(按A/Goose/Guangdong/1/96毒株排序)发生缺失,导致该处增加了1个糖基化位点;同时受体结合位点的口袋右缘发生L145S的变异,而这一位点的变异在2016年的毒株就已产生;2017的毒株另有12个aa发生了较为一致的变异。故推测当前毒株的抗原性已发生了较大变化。但238位(H3排序226位)匀为Q,保持禽源毒株的特征。就当前而言需改用Re-11或rFJ56株疫苗才能起到好的效果。

The H5 subtype of avian influenza virus of clade 2.3.4.4 has been prevalent for several years in china.Whether the epidemic strain will cause immune failure due to mutation has aroused concern.In this study,the epidemic strains from 2014 to 2017 were sequenced,and the variation of their antigenic sites was compared and analyzed.The results showed that the epidemic strains in 2017 had changed greatly,forming an independent branch.The difference between the nucleotide sequence of the previous strains in HA is 4.4%-5.4%.The main variation is in the 142 E HA protein(sorted by A/Goose/Guangdong/1/96 strain)deletion,lead to one glycosylation sites were added to the site;at the same time the receptor binding sites of mutation L145 S occurred on the right edge of the pocket,and2016 strains variation had been produced.In addition,2017 of the strains have 12 aa variations.Therefore,it is speculated that the antigenicity of the current strains has changed greatly.But the 238 aa(H3 order 226)was Q and kept the characteristics of the avian influenza virus.Currently,Re-11 or rFJ56 vaccines need to be switched to achieve good results.