Objective To understand genetic mutation of influenza virus hemagglutinin (HA) and its antigenic drift in Mentougou District during 2013-2014. Methods The throat swab specimens of influenza-like illness ( ILI) were detected using the method of real time transcription reverse-polymerase chain peaction for influen-za virus nucleic acid at sentinel surveillance hospital in Beijing Mentougou District from 2013 to 2014, and ten isolated strains were selected randomly and their sequences of the HA genes were analyzed by the bioinformatics software merge for homologous alignment and phylogenetic tree of HA gene was constructed. Results Compared with WHO recommended influenza vaccine strain B/Wisconsin/1/2010 in the Northern Hemisphere from 2012 to 2013, 6 amino acid positions were replaced. Compared with influenza B vaccine strain B/Massachusetts/2/2012 in the Northern Hemisphere from 2013 to 2014, 15 amino acid positions was found displaced . The evolutionary tree showed that the genetic relationship of these 10 influenza B viruses with B/Wisconsin/1/2010 was the closer, the difference between these 10 influenza B Viruses and B/Massa-chusetts/2/2012 were larger. Conclusion The influenza B virus isolated in Mentougou District from 2013 to 2014 have changed in genetic character resulting in altered antigenicity of influenza B virus, which indicating that antigenic variation in influenza B virus persists. It was important for discovering the new mutant of virus strain in time to enhance the influenza surveillance.%目的：了解北京市门头沟区2013-2014年乙型流感病毒血凝素（HA）基因突变及其抗原变异情况。方法将北京市门头沟区2013-2014年流感哨点监测医院采集的流感样咽拭子进行核酸、病毒分离检测，随机抽取分离得到的10株乙型流感病毒进行HA基因序列测定，对测序产物进行分析，用MEGA软件进行同源性比对、构建HA基因进化树。结果抽取的10株乙型流感病毒的HA基因与WHO推荐的2012-2013年度北半球流感疫苗株B/Wisconsin/1/2010比对, HA区6个氨基酸位点发生替换；与2013-2014年度北半球流感疫苗株B/Massachusetts/2/2012比对，HA区15个氨基酸位点发生替换。绘制的种系发生树显示，分离到的毒株与B/Wisconsin/1/2010亲缘关系较近，与B/Massachusetts/2/2012差异较大。结论北京市门头沟区乙型流感病毒的HA基因发生变化，导致乙型流感病毒抗原性发生改变，表明抗原变异在乙型流感病毒中持续发生，流感病原学监测工作的开展对及时发现新的流感病毒变异株有重要意义。
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