2010-2011年北京市儿童甲型H3N2流感病毒的血凝素基因特征和遗传进化分析

目的了解2010年9月1日～2011年8月31日北京市儿童甲型H3N2流感活动特点,并对病毒血凝素的基因和进化特征进行研究。方法采集哨点医院收集的1 040份儿童流感样病例样本和14份疫情样本,进行MDCK细胞分离病毒。选取26株甲型H3N2流感毒株进行血凝素(HA1)基因的扩增和序列测定。采用生物信息软件进行序列比对和进化分析。结果 2010-2011年流感监测季期间,总共分离64株甲型H3N2毒株,占分离毒株构成的65.31%。病毒HA1基因出现了Ⅰ、Ⅱ两个明显分支,均有S214I氨基酸变异。另外,分支I的毒株序列还均出现P162S、R261Q氨基酸变异;分支II的毒株序列均出现D53N、K62E、Y94H、K144N、T212A、I230V氨基酸变异,涉及A、C两个抗原决定簇,并新增1～2个糖基化位点。结论 2010年9月～2011年2月期间北京市儿童甲型H3N2流感活动活跃,并且其毒株呈现出两个明显不同的进化分支,其中一个分支毒株的血凝素基因特性发生了明显改变。

Molecular characterization of HA1 genes and phylogenetic analysis of H3N2 virus in Beijing children during 2010-2011

Objective To understand the activity of influenza H3N2 in Beijing children during the period from Sep.,2010 to Aug.,2011.Methods A total of 1040 pharyngeal swab specimens from surveillance systems as well as other 14 specimens from two outbreaks were collected and cultured by MDCK cell.HA1 genes of the selected 26 virus strains were amplified and sequenced.Furthermore,sequence alignment and phylogenic analysis were performed using bioinformatics software.Results In this study,a total of 64 H3N2 virus strains were isolated,accounting for 68.1% proportion of total isolated influenza virus strains.HA1 genes of influenza H3N2 viruses showed two genetically divergent clusters.Those of cluster Ⅰ virus strains had P162S、S214I、R261Q amino acid substitutions,while those of cluster Ⅱ contain D53N、K62E、Y94H、K144N、S214I amino acid mutations relating to antigenic site of A or C and had more than one or two glycosylation sites compared with those of vaccine strain of A/Perth/16/2009.Conclusions Seasonal influenza H3N2 viruses were viewed an active circulation from Sep.2010 to Feb.2011 in children and the genes of HA1 of those virus strains showed obviously two genetic divergences of evolution pathway.