唐山市甲型H1N1流感病毒血凝素基因序列分析

目的 分析2010—2016年唐山市甲型H1N1流感病毒血凝素(hemagglutinin,HA)基因序列进化特征.方法 选取唐山市3家哨点医院流感样病例分离到的24株甲型H1N1病毒,通过RT-PCR和测序方法获得HA基因的全长序列,运用分子生物学软件和统计学软件对序列进行拼接、比对和分析.结果 同源进化分析显示,24株甲型H1N1流感病毒HA基因与疫苗株A/California/7/2009的核苷酸和氨基酸的同源性分别为97.0%~99.0%和97.0%~98.5%.进化分析显示,2010—2016年唐山地区流行的甲型H1N1流感病毒属于1、7、6三个基因分支,其中6分支毒株分为6C、6B、6B.1和6B.2亚支.氨基酸位点分析显示,不同毒株与疫苗株比较存在8~16处氨基酸位点改变,其中7个变异涉及3个抗原表位:H138Q/Y和S203T突变位于Ca区,N125S、K153E、S162N、K163T/Q突变位于Sa区,S185T突变位于Sb区同时也位于受体结合部位;2015—2016流行季6B.1分支毒株抗原位点S162N突变增加了新的潜在糖基化位点.结论 与疫苗株比较,随着时间推移唐山地区甲型H1N1流感病毒发生了抗原漂变,未来仍应关注6B分支流行株的变化.

Sequence analysis of Hemagglutinin of influenza A(H1N1)pdm09 viruses in Tangshan

Objective To analyze the evolutionary characteristics' of hemagglutinin (HA) gene of pandemic influenza A (H1N1) pdm09 virus isolated from Tangshan city during influenza seasons druing 2010-2016. Methods A total of 24 influenza A(H1N1)pdm09 virus strains isolated from patients with influenza-like illness (ILI) in 3 sentinel hospitals in Tangshan were selected, and the full-length sequences of HA gene were obtained. The bioinformatical and statistical softwares were applied to align and to analyze all the sequences. Results Compared with the vaccine strain A/California/7/2009, the HA genes of 24 A (H1N1) pdm09 strains showed 97.0%-99.0% nucleotide identity and 97.0%-98.5% amino acid sequence identity. Phylogenetic analysis showed all the 24 A (H1N1) pdm09 strains fell into HA genetic clades 1, 7, 6C, 6B, 6B1, and 6B.2, respectively. Amino acid analysis of the isolates revealed the presence of 8-16 changes in HA gene compared to the vaccine strain, seven of which occurred in three antigenic sites: H138Q/Y and S203T in Ca; N125S, K153E, S162N and K163T/Q in Sa; and S185T in Sb. The S162N substitution, specific to subclade 6B.1, generated a new potential N-glycosylation motif within the Sa antigenic site. Conclusions Compared to vaccine strain, the genetic drift of the Tangshan influenza A(H1N1) pdm09 viruses in Tangshan occurred as time went on, we should pay attention to the changes of epidemic strains in 6B branch.