2014 - 2015年盐城地区乙型流感病毒Yamagata系HA1基因变异分析

目的 研究盐城市2014 - 2015年流感监测中分离的乙型Yamagata系流感病毒血凝素HA1区的基因特性，揭示HA1基因的变异与流行的关系。方法 将盐城市2014 - 2015年流感监测哨点医院以及流感暴发点采集的流感样病例标本进行核酸、病毒分离检测，选取2014-2015年各5株乙型Yamagata系毒株，采用一步法RT-PCR方法扩增HA1基因，扩增产物经纯化测序，采用相应的生物信息软件进行核苷酸、氨基酸序列比对及基因种系进化特征分析。结果 抽取的10株乙型流感病毒的HA1基因与WHO 推荐的疫苗株B/Wisconsin/1/2010相比，3个位点氨基酸替换具有普遍性，其中N116K位于抗原决定簇；与B/Massachusetts/2/2012相比，11个位点氨基酸替换具有普遍性，4个位点位于抗原决定簇。绘制的种系发生树显示，B/JSYC/1530/2014与B/Massachusetts/2/2012亲缘关系较近，其他9株与B/Wisconsin/1/2010 亲缘关系较近。 结论 2014 - 2015年盐城地区流行的乙型Yamagata系流感病毒的HA1基因特性正逐渐发生变异，这些变异位点的积累很可能会导致流感病毒发生实质性的抗原性的漂移，加强流感病原学监测工作对及时发现新的流感病毒变异株有重要意义。

Characteristics Analysis of HA1 gene of the Yamagata lineage influenza B virus isolated in Yancheng area during 2014 -2015

Objective This study was to analyze the characteristics of the HA1 gene of the Yamagata lineage influenza B virus isolated in the city of Yancheng during 2014-2015. Methods During 2014-2015, the throat swab specimens of patients with influenza-like symptom from sentinel surveillance hospital and outbreak sites were tested using the method of real time RT-PCR for influenza B viruses, which were then isolated using MDCK cells culture method .Ten isolated strains were selected randomly and their HA1 gene sequences were amplified through one step RT-PCR method and the PCR products were then sequenced. The mutations in this gene were analyzed and the evolution trees were generated using bioinformatics software. Results Compared with WHO recommended influenza vaccine strain B/Wisconsin/1/2010 in the Northern Hemisphere from 2014 to 2015, the amino acids at 3 positions were replaced universally. Among them,1 locus(N116K) was located in antigenic determinant. Compared with influenza B vaccine strain B/Massachusetts/2/2012 in the Northern Hemisphere from 2014 to 2015, the amino acid at 11 positions were replaced universally. Among them, 4 loci were located in antigenic determinant. The evolutionary tree showed that the genetic relationship of B/JSYC/1530/2014 was closer with B/Massachusetts/2/2012 , and the genetic relationship of other 9 strainswas closer with B/Wisconsin/1/2010 . Conclusion These results indicated that the hemagglutinin genes of the Yamagata lineage influenza B virus circulating in Yancheng area from 2014 to 2015 changed gradually. The accumulation of these mutations would result in antigenic drift of the Yamagata lineage influenza B virus. The influenza surveillance should be strengthened to find the new mutant of virus in time．