江苏省2013至2015年人H7N9流感病毒的分子特征

Molecular characteristics of human influenza A(H7N9) virus in Jiangsu province from 2013 to 2015

目的探讨江苏省2013至2015年人源H7N9禽流感病毒的分子特征。方法从全球禽流感共享数据库（GISAID）中下载江苏省2013至2015年上传的人感染H7N9禽流感病毒株（37株）和禽源性H7N9病毒株（7株）的全基因序列,用MEGA6.0软件分析人感染H7N9禽流感病毒HA、NA、M及PB2等基因的分子遗传特征、关键氨基酸位点的改变情况,并构建HA和NA的系统进化树。结果江苏省内人源和禽源H7N9禽流感毒株与参考株相比较,HA蛋白的差异均较小,其同源性分别为97.2%～100%和98.2%～100%;NA蛋白之间的差异也较小,其同源性分别为99.8%～100%和99.9%～100%;人源与禽源H7N9病毒HA或NA之间的同源性分别为98.5%～100%和99.8%～100%。人源和禽源H7N9毒株的HA蛋白均发生G186V和D225G变异,44株发生Q226L变异,4株出现A134V变异,但HA的裂解位点均未发生改变。2013年1株NA蛋白出现R294K耐药位点的变异。PB2蛋白分析显示：所有毒株均发现L89V变异,其中人源H7N9毒株中,26株发现E627K变异,5株发现D701N变异。所有毒株的M2蛋白均发生S31N变异。结论江苏省2013-2015年人感染H7N9流感病毒与禽源性H7N9毒株的氨基酸序列高度同源,关键氨基酸位点的变异与人感染该病毒密切相关,应加强人源和禽源H7N9病毒的分子监测。

Objective To explore the molecular characteristics of human and avian influenza A（ H7N9） virus from 2013 to 2015 in Jiangsu province. Methods The whole gene sequences of influenza A（ H7N9） virus strains originated from Jiangsu province between2013 and 2015 were obtained by global sharing of avian influenza database（ the Global Initiative on Sharing Avian Influenza Data,GISAID）,including human（ 37 strains） and avian-borne H7N9 strains（ 7 strains）. The MEGA6. 0 software was used to analyze the molecular characteristics and the key positions of amino acids of HA,NA,M and PB2 genes from influenza A（ H7N9） virus,and the phylogenetic trees of HA and NA were also established by this software. Results Compared with reference strains of influenza A（ H7N9） virus,a little difference was observed in the homology of HA protein of human or avian-borne influenza A（ H7N9） virus strains,and the homologies of human and avian-borne H7N9 virus were 97. 2% to 100% and 98. 2% to 100%,respectively. The homologies of NA protein were 99. 8% to 100% and 99. 9% to 100%,respectively. The homologies of HA were 98. 5% to 100%,and NA were 99. 8% to 100% between human and avian-borne H7N9 virus,respectively. The analysis of amino acids variation indicated that many key positions of HA protein in human and avian H7N9 virus mutated,such as G186 V and D225 G mutation in 47 strains,Q226 L mutation in 44 strains,A134 V mutation in 4 strains. However,no change of cleavage site in the sequences was found. There was only one strain with R294 K mutation of NA protein in 2013. Many variations of PB2 protein were observed,such as L89 V mutation in all strains,E627 K mutation in 26 strains and D701 N in 5 strains from human. The S31 N mutation of M2 protein was found in all strains. Conclusion The high homology between human and avian influenza A（ H7N9） virus was demonstrated in Jiangsu province from 2013 to 2015,and the key sites of amino acid mutations may associate with human H7N9 virus infection. The surveillance for the molecular characteristics of human and avian-borne H7N9 virus should be strengthened.