2019—2020流感监测年度山东省B-Victoria系流感病毒基因特征

Analysis of genetic characteristics of B-Victoria strains of influenza virus in Shandong Province during the influenza surveillance year from 2019 to 2020

目的了解2019—2020流感监测年度山东省B-Victoria系流感病毒流行规律及基因特征,为B型流感疫苗的接种提供参考依据。方法对2019—2020流感监测年度监测数据进行分析,采用多阶段抽样方法随机抽取B-Victoria系流感病毒毒株进行基因序列的测定,采用Mega X软件的Muscle方法进行多序列比对,用Neighbor-Joining方法进行系统发育分析。结果2019—2020流感监测年度流感病毒以B-Victoria系和H3N2亚型为主;20株流感病毒毒株的基因进化分析表明其与同期疫苗株B/Colorado/06/2017亲缘关系较远却与下一年度疫苗株B/Washington/02/2019关系较近且共同聚集在Clade1A(Δ3)分支上,与同期疫苗株B/Colorado/06/2017相比有13处氨基酸位点改变,其中有5处位于抗原决定簇,其最大变异率为1.91%;糖基化分析显示20株流感病毒毒株全部发生209位糖基化位点增加;20株流感病毒毒株均未发现耐药位点突变。结论2019—2020流感监测年度推荐疫苗保护效果可能不理想,但山东省B-Victoria系流感病毒毒株对神经氨酸酶抑制剂依旧敏感。今后应继续密切关注B-Victoria系流感病毒的流行与基因变异情况,为B型流感病毒疫苗株的推荐及B型流感的防控提供依据。

Objective The study aims to analyze the prevalence and genetic characteristics of the B-Victoria strain of influenza virus in Shandong Province from 2019 to 2020 monitoring year,and providing a reference for the vaccination of influenza B vaccine.Methods The surveillance data of influenza surveillance from 2019 to 2020 were analyzed.B-Victoria strain of influenza were randomly selected by multi-stage sampling method for gene sequence determination,multi sequence alignment was carried out by Muscle method of Mega X software,and phylogenetic analysis was carried out by Neighbor-Joining method.Results The B-Victoria line and H3N2 subtype were the main types from 2019 to 2020 monitoring year.The phylogenetic analysis showed that the 20 strain was far from B/Colorado/06/2017,but close to B/Washington/02/2019 in the next year,and clustered on clade1 A(Δ3)branch.Compared with B/Colorado/06/2017,there were 13 amino acid changes,of which 5 were located in antigenic determinants,with the maximum variation rate of 1.91%.Glycosylation analysis showed that all the 20 strains had an increase of 209 glycosylation sites,and no mutation was found in the 20 isolates.Conclusions The protective effect of the recommended vaccine from 2019 to 2020 may not be ideal,but B-Victoria strain in Shandong Province is still sensitive to neuraminidase inhibitors.We should continue to pay close attention to the prevalence and genetic variation of B-Victoria influenza virus in the future,so as to provide a basis for the recommendation and prevention of influenza B virus vaccine strains in the future.