贵阳市2012-2015年B型流行性感冒病毒血凝素基因特性分析

目的 了解2012-2015年贵阳市B型流行性感冒（以下简称流感）病毒的变异和流行特点，分析其与WHO推荐的疫苗株和我国的代表株匹配情况。方法 将21份标本进行血凝素基因片段1（haemagglutinin 1，HA1）基因序列测定，通过DNA Star version 7.1等软件对测序产物进行分析。结果 贵阳市B型流感病毒存在BY和BV两种谱系；核苷酸同源性显示，BV系与疫苗株B/Brisbane/60/2008的同源性为97.8%~99.3%；2013-2014年BY系与疫苗株B/Massachusetts/02/2012的同源性为96.2%~96.5%，与既往的疫苗株B/Wisconsin/01/2010同源性为99.0%~99.3%；2015年BY系与疫苗株B/PHUKET/3073/2013同源性为99.2%~99.5%；2012-2015年BV系与我国代表株B/Chongqing-Yuzhong/1384/2010同源性为96.8%~99.0%，BY系与种子疫苗株B/Hubei-Wujiagang/158/2009为98.2%~99.2%。与当年度疫苗株相比，2013-2014年BY系毒株有9个氨基酸位点发生变异，其中A134P位点涉及到抗原决定簇A区，N142K涉及到B区；2015年BY系毒株发生新的L198Q变异，且涉及到D区；BV系氨基酸位点替换多样，但很少涉及到抗原决定簇。结论 2012-2015年贵阳市人群中B型流感病毒在不断地发生改变，除2013-2014年疫苗株与流行株匹配性不佳以外，其余年度的匹配性均较好，能起到保护作用。

Genetic characteristic of haemagglutinin of influenza B virus in Guiyang, 2012-2015

Objective To understand the genetic variation and epidemiological characteristics of influenza B virus in Guiyang, Guizhou province, in 2012-2015, and to evaluate the matching situation of epidemic strains and the influenza vaccine strains recommended by WHO and China. Methods The haemagglutinin segment 1(HA1) nucleotide sequences of 19 strains and 2 positive specimens of influenza B viruses were determined by Sanger dideoxy sequencing, the sequencing products were analyzed by bioinformatics software DNAStar version 7.1. Results Both BY and BV lineage of influenza B viruses were found to co-circulate in Guiyang.Results of homology analysis revealed that there were 97.8%~99.3% homology in nucleotide between BV lineage viruses and vaccine strain B/Brisbane/60/2008. However, vaccine strain B/Massachusetts/02/2012 showed a lower homology (96.2%-96.5%) to BY lineage viruses than previous vaccine strain B/Wisconsin/01/2010 did (99.0%-99.3%). BY lineage viruses had a high homology to vaccine strain B/PHUKET/3073/2013 recommended by WHO in 2015, with homology ranged from 99.2% to 99.5%. During 2012-2015, Chinese representative strain B/Chongqing-Yuzhong/1384/2010 had 96.8%-99.0% homology to BV lineage viruses, meanwhile, another Chinese vaccine seed strain B/Hubei-Wujiagang/158/2009 had 98.2%-99.2% homology. Compared to the current vaccine strain recommended by WHO, amino acid sequence alignment analysis showed there were 9 amino acid mutations in HA1 fragment of BY lineage strains in 2013-2014, the mutation of A134P was related to antigenic determinant site A, N142K was related to site B. There was a new amino acid mutation of L198Q relating to antigenic determinant site D in HA1 fragment of BY lineage strains in 2015. There were different kinds of amino acid mutations in HA1 fragment of BV lineage strains, which were rarely related to antigenic determinant site. Conclusions Genetic characteristic of influenza B virus was constantly changing in Guiyang in 2012-2015. Overall, the predominant circulating influenza B viruses in 2013-2014 in Guiyang could be not provided a good protection by current influenza vaccine, but the rest years of influenza B viruses were matched by current influenza vaccines with a good protective effect.