Genetic characteristics of HA gene of influenza A(H3N2)virus in Chaoyang district of Beijing from 2007 to 2019
Objective To explore the genetic variation of the HA gene of influenza A(H3N2)virus in Chaoyang district of Beijing,so as to provide basic data for the evaluation of the vaccine efficacy.Methods The sequences of recommended influenza vaccine strains and representative strains by World Health Organization from 2007 to 2019 were downloaded from the Global Initiative on Sharing All Influenza Data(GISAID),and were used for the phylogenetic analysis,amino acid variation analysis and the evaluation of vaccine efficacy.with the HA gene sequence of influenza A(H3N2)virus strains in the present study.Results Most influenza A(H3N2)virus strains in and before 2015 belonged to 3C.3a branch,and strains in 3C.2a branch started to be dominant from 2016.In 2017,the dominant strains were in 3C.2a2 sub-family and evolved to 3C.2a3.In 2019 the dominant strains returned to 3C.3al sub-family.In 2009,2013 and 2015,there existed co-circulation of strains in 3C.2 and 3C.3 branches.There were 54 amino acid variation sites in the epitopes A to D in HA gene.Amino acid mutations occurred in the 130 loop region,190 helix region and 220-ring region.The deletion/addition/conversion of glycosylation sites occurred every year,mostly in the HA1 region.The vaccine efficacy was predicted to be 5％-47％(PepitopeMax:0-0.2105).Conclusions The evolution of HA gene of of influenza A(H3N2)virus in Chaoyang district of Beijing from 2007 to 2019 showed diversity and complexity with possible antigen drift.The matching of epidemic strains with recommended vaccine strains were poor in some years,suggesting the necessarity of continuous surveillance the HA gene variation of influenza A(H3N2)virus.
Influenza A H3N2 virusSurface glycoprotein geneHemagglutininAmino acid variationVaccine efficacy
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