2017年北京市丰台区6例乙型Victoria系流感病HA1基因特征分析

目的 了解2017年北京市丰台区流感暴发疫情中乙型Victoria系（BV）流感毒株血凝素（HA1）基因特征和变异情况。 方法 对北京市丰台区2017年6起BV流感暴发疫情病例标本中分离得到的6株毒株的HA1基因进行提核酸、扩增和测序，通过DNAStar 7.1、Bioedit v7.0.9、Mega 6.0.6 等生物信息学软件对序列进行分析。结果 6例样本中1号样本与2017年部分日本流行毒株亲缘关系较近(99.6%)；另5例样本与2016年我国厦门、泰国和肯尼亚部分流行毒株的亲缘关系较紧密（99.1%～99.8%）。6例样本与WHO推荐的疫苗株B/Brisbane/60/2008的同源性为98.6%。6例样本共有7个位点发生了变异，其中有5例样本发生了I132V、N144D 和E200D的变异，分别涉及到抗原决定簇A、B、D3个区。结论 北京市丰台区2017年BV系流感株的HA1基因发生了个别位点的变异，但与WHO推荐的疫苗株B/Brisbane/60/2008的匹配度相对较高，继续使用疫苗对BV系病毒引起的流感能起到积极的预防作用。

Analysis of HA1 gene of 6 cases of influenza virus type B victoria lineage in Fengtai District of Beijing in 2017

Objective To understand the characteristics and variation of hemagglutinin (HA1) gene of influenza B virus Victoria lineage in Fengtai District of Beijing in 2017. Methods The HA1 gene of 6 isolated influenza BV outbreak cases were extracted, amplified and sequenced. And sequences were analyzed by bioinformatics software such as DNAStar 7.1, Bioedit v7.0.9, and Mega 6.0.6. Results Among the 6 samples, the 1st sample was closely related (99.6%) to some Japanese epidemic strains in 2017; the other 5 samples were closely related to the 2016 Pandemic strains of Xiamen, Thailand and Kenya(99.1%-99.8%). The homology of 6 samples with the WHO-recommended vaccine strain B/Brisbane/60/2008 was 98.6%. A total of 7 sites were mutated in 6 samples, and there were 5 samples(5/6) had mutations occurred in I132V, N144D, and E200D, which involved the three regions of antigenic determinants A, B, and D, respectively. Conclusion The HA1 gene of BV strains in the Fengtai District of Beijing had been mutated at individual sites, but the matching degree with the WHO-recommended vaccine strain B/Brisbane/60/2008 is relatively high. So continued use of the vaccine against the BV strain can play a positive preventive effect.