宜春市2011年-2013年乙型流感病毒HA1基因特性分析

Analysis of HA1 genetic characterizations of influenza B viruses isolated in Yichun from 2011 to 2013

目的了解宜春市2011年-2013年分离的B型流感病毒株HA1基因变异情况。方法核酸提取采用逆转录-聚合酶链反应（RT-PCR）扩增病毒基因后进行核苷酸序列测定,用DNAStar510、Bio Edit（Version510）、Mega3.1生物软件对测序结果进行分析处理。结果 Victoria系11株,Yamagata系7株进行HA1基因测序,与当年WHO对北半球推荐的疫苗株进行比对,2011年、2012年、2013年氨基酸同源性分别为99.1%、99.4%-99.6%、99.4%-99.6%;氨基酸替换数分别为3个、3个、4.5个,其中2012年1处、2013年2处变异位于抗原决定簇;种系进化树上,分成Victoria系和Yamagata系两大分支,各年份同系分离株与疫苗推荐株均在同一分枝上,亲缘性较近;HA1基因序列二硫键未发生变异;糖基化位点仅2013年两毒株分别在533-535、546-548发生了变异。结论 2011年-2013年宜春市B型流感HA1基因虽然有氨基酸替换,但还没有出现实质性的转变,且与疫苗代表株同源性极高,均达到99.1%以上,因此疫苗仍具有较好的保护作用。

Objective To understand the HA1 genetic variation characterizations of influenza B viruses isolated in Yichun from2011 to 2013. Methods RNA was extracted from influenza B viruses,then their HA1 genes were amplified by reverse transcription polymerase chain reaction（ RT- PCR）. The PCR products were sequenced and the data obtained were analyzed with the software DNAStar 5. 0,Bio Edit（ Version 510） and Mage 3. 1. The amino acid sequences was deduced,then gene conversion levels were assessed. Results HA1 gene was sequenced in 11 strains of Victoria strain and 7 strains of Yamagata strain.The amino acids sequences of HA1 region of 18 strains compared with vaccine strain recommended by WHO. Compared with the vaccine strain recommended by WHO in the northern hemisphere,the amino acid homology was 99. 1%,99. 4%- 99. 6%,99. 4%- 99. 6% in 2011,2013 and 2012,respectively; the number of amino acid substitutions were 3,3,4. 5,in which one mutation in 2012 and two mutations in 2013 located in the antigenic determinant; The phylogenetic tree was divided into two branches of Victoria and Yamagata system. Each year syngeneic isolated strains and vaccine recommended strains were in the same branch with close affinity. There was no variation on disulfide bond of HA1 gene,and there was only 2 strains of 2013 have variation on the glycosylation site from 533 to 535 and 546 to 548. Conclusion Although there was substitutions of amino acid on HA1 regions of influenza B viruses in Yichun from 2011 to 2013,there was no substantial transformation,and the homology with vaccine representative strain all reached 99. 1%,so vaccine still had protective effect.