2012-2013流感监测年度中国大陆B型流感病毒抗原性及基因特性分析

目的了解2012-2013流感监测年度中国大陆地区B型流感的流行状况,分析B型流感病毒的抗原性和基因变异情况。方法选择2012-2013年我国分离的B型流感病毒,利用标准雪貂抗血清进行抗原性分析。利用Sanger测序法进行病毒基因测序,采用Neighbor-Joining方法进行种系进化分析,通过基因进化树比较国内流行株与疫苗株的差异。结果 2012-2013监测年度内,B型流感病毒占所有流感病毒的9.93%,其中以B型Victoria系流感病毒为主。B型Victoria系流感病毒的抗原性与上一年度WHO推荐的疫苗株B/Brisbane/60/2008(83.5%)以及我国代表株B/Chongqing-Yuzhong/1384/2010(94.7%)的抗原性类似;而B型Yamagata系流感病毒绝大多数为WHO疫苗株B/Wisconsin/01/2010(99.3%)、WHO疫苗种子株B/Hubei-Wujiagang/158/2009(98.0%)的类似株;基因特性分析显示有1株B-Victoria系病毒发生了HA与NA基因分支间的重配,有1株B-Yamagata系病毒B/Sichuan-Gaoxin/1110/2012的NA基因位于Victoria系病毒的NA进化分支,也表明发生了种系间的基因重配。结论 2012-2013流感监测年度我国B型流感病毒活动水平较低,主要以Victoria系为主,而WHO推荐的疫苗组分是B-Yamagata系病毒,可见部分B型流感流行株与疫苗株并不匹配。

Antigenic and genetic characteristics of influenza B virus in the mainland of China, 2012 - 2013

Objective To understand the epidemiological characteristics of influenza B and the antigenic and genetic characteristics of influenza B virus in the mainland of China during 2012 - 2013. Methods The antigenic characteristics of influenza B virus was analyzed with reference ferret anti-sera. The nucleotide sequences of the influenza B viruses were determined by Sanger dideoxy sequencing. The phylogenetic trees were constructed by neighbor-jointing method, the genetic characteristics were determined and compared the circulating influenza B virus with current vaccine strains. Results During 2012 - 2013 influenza season influenza B virus accounted for 9.93% of total influenza viruses detected, the activity of B Victoria lineage virus were stronger than B Yamagata lineage virus. Most B Victoria lineage viruses had close antigenic relation with the vaccine strain B/Brisbane/6012008 （83.5% ） recommended by WHO in previous year and the representative circulating strain B/Chongqing- Yuzhong/1384/2010 （94.7%） in the mainland of China. The majority of B Yamagata lineage viruses had closely antigenic relation with WHO recommended vaccine strain B/Wisconsin/01/2010 （ 99. 3%） and WHO vaccine seed B/Hubei-Wujiagang/158/2009 （ 98. 0% ）; phylogenetic analysis on B Victoria lineage viruses indicated that one strain had intra-clade reassortants between HA and NA gene. One of the B Yamagata lineage viruses, B/Sichuan-Gaoxin/1110/2012, was confirmed to be an intra-lineage reassortant with NA gene from B Victoria lineage. Conclusion The activity of B Victoria lineage virus was stronger than Yamagata lineage virus in the mainland of China during 2012 -2013 influenza season, but only Yamagata lineage virus was included in the WHO recommended trivalent influenza vaccine for this period, which could not provide protection to B Victoria lineage virus infection.