2017-2018年北京市乙型流感病毒Victoria系HA的抗原性及基因特性分析

Antigenicity and genetic characterization of HA gene in influenza B/Victoria-lineage virus in Beijing 2017-2018

目的了解北京市2017—2018监测年度乙型流感病毒Victoria系(BV)血凝素(HA)基因的抗原性及基因特征。方法收集北京市17个流感病原学监测实验室经MDCK细胞培养分离得到的BV流感病毒30株,以WHO推荐的BV流感疫苗株为参考毒株进行抗原性分析;另外,提取BV病毒的总核酸作为模板,进行HA片段全长的RT-PCR扩增和HA基因测序及突变分析。结果30株BV流感毒株的抗原性分析结果:23株为低反应株(76.7%),7株为类似株(23.3%);30株BV流感毒株基因特性分析结果:HA基因的遗传进化树分析显示都位于Clade 1A分枝,有8个位点发生氨基酸变异,其中6个变异位点位于抗原决定簇。结论2017—2018年度分离的BV流感病毒HA区域涉及的抗原决定簇的6个位点的变异与抗原性低反应株的比例高有一定的相关性,该结果为流感疫苗的推荐提供了重要的实验室依据。

Objective To understand the antigenicity and genetic characterization of influenza B virus HA gene in B/Victoria-lineage virus(BV)in Beijing during 2017-2018.Methods Thirty BV virus strains isolated from MDCK cell culture by 17 laboratories in Beijing were collected.The antigenicity was analyzed by comparing with the vaccine strain recommended by WHO.The total viral nucleic acid was extracted and HA gene was amplified by RT-PCR and sequenced.The phylogenetic tree was constructed by HA and mutant sites were analyzed.Results Among 30 strains of BV,23 strains(76.7%)were low-reactive strains,other 7 strains(23.3%)were related to the vaccine.The phylogenetic analysis showed that the HA gene of all 30 strains located in Clade 1A branch.In addition,amino acid mutations occurred in 8 sites,and 6 of them located in the antigen determining region.Conclusions There was a correlation between the high proportion of low-reactive antigenicity and 6 aa variation in antigenic determinants involved in HA region of BV influenza virus between 2017-2018,which provides an important laboratory basis for the recommendation of BV influenza vaccine.