新型甲型H7N9流感病毒血凝素基因进化分析

目的探讨2013年4月流行的新型甲型H7N9禽流感病毒的表面蛋白血凝素(HA)基因的进化,以及氨基酸的变异情况。方法从美国国家生物技术信息中心(NCBI)和全球禽流感基因共享数据库(GISAID)中下载H7N9流感病毒以及有代表性的H7N2、H7N3、H7N7亚型流感病毒的HA基因序列,运用Molecular Evolutionary Genetics Analysis(MEGA)version 5.05软件进行序列分析,用邻接法构建基因进化树;通过氨基酸序列分析HA蛋白受体结合位点、糖基化位点和裂解位点的变化。结果 2013年新型甲型H7N9流感病毒与2011年浙江禽类H7N3流感病毒株(JQ906573.1)的相似性达到95.3%～95.6%;受体结合位点氨基酸发生变异,为Q226L,5个糖基化位点高度保守;HA裂解位点位于aa339和aa340之间,仅有1个碱性氨基酸:R。结论 2013年新型甲型H7N9流感病毒HA基因是由中国禽类H7亚型进化而来,Q226L变异导致的受体结合位点的变化可能是新型流感病毒具有人感染性的原因。

Phylogenetic analysis of hemagglutinin (HA) gene of the novel avian influenza virus A/H7N9

Objective: To analyze the evolutionary resource and amino acid site variation of the new avian influenza virus A/H7N9 in 2013 epidemic. Methods: HA genes sequence of A/H7N9 and H7N2,H7N3,H7N7 subtypes were downloaded from NCBI and GISAID. MEGA4.0 and N-J method were used to construct the phylogenetic trees and gene sequence alignment. Receptor bind sites, glycosylation sites and cleavage sites were analyzed by amino acid sequence alignment. Results: HA genes similarity of new A/H7N9 in 2013 with A/H7N3/Zhejiang (JQ906573.1) in 2011 was more than 95%. There was a variation in 235 amino acid site. Potential glycosylation sites were conserved. Two basic amino acids existed around the HA cleavage site in novel strain. Conclusion: The HA gene of novel strains of H7N9 in 2013 might originate from H7 subtypes carried by avian in China. The variation of amino acid may lead the change in receptor bind sites and host range.