广东地区流感H3N2毒株血凝素基因特征、进化和变异分析

为揭示广东地区2007～2010年甲型H3N2毒株血凝素(HA)基因特征和变异，采用时空抽样方法抽样，检测广东2007～2010年甲型H3N2毒株HA基因核苷酸序列，同时检索全球HA基因序列作为对照，采用Lasergene 7.1和Mega 5.05软件对HA基因核苷酸序列进行比对和分析；并结合流行病学资料，对变异毒株进行进化速度分析；同时进行抗原分析。结果发现，广东2007～2010年H3N2毒株HA基因同义进化(Ks)和错义进化(Ka)速度分别为2.06×1E-3～2.23×1E-3核苷酸/年和1.05×1E-3～1.21×1E-3核苷酸/年，HA1较HA2的错义突变速率要高3.13倍。与疫苗株A/Perth/16/2009的HA基因比较，2009年广东毒株同源性达到98.8%～99.7%、2010年同源性达到98.0%～98.4%。在广东2007～2010年毒株中，HA1五个抗原表位均有氨基酸位点变异，尤其是2010年毒株B区(N160K)和D区(K174R/N)的变异；此外，广东2010年毒株受体结合部位(RBS)还发生K189E/N/Q和T228A置换变异；两个糖基化位点变异影响到抗原性；目前使用的H3N2疫苗株与目前流行毒株的抗原性有差异。广东地区2007～2010年的毒株中，血凝抑制抗体的抗原分析结果有差异。结果提示，目前广东乃至全球甲型H3N2毒株HA1B区和D区均有氨基酸位点变异，RBS的两个位点发生置换，糖基化位点变异影响到表位A区和B区抗原性；与WHO推荐2011年流感H3N2毒株疫苗株比较，目前流行毒株HA基因有抗原位点变异。

Molecular Evolution of Human Influenza H3N2 Virus Hemagglutinin Genes in Guangdong China

The molecular characterization and phylogenetic analysis of hemagglutinin(HA) genes of human influenza H3N2 viruses in Guangdong,China from 2007 to 2010 were studied in this study.By space-time sampling of strains,the HA genes of H3N2 strains from Guangdong were sequenced and searched from Internet,and then the variation and evolution of HA genes were conducted by Lasergene 7.1 and Mega 5.05 and evolutionary rates were analyzed by epidemiological data.The phylogenetic tree was established by alignment of 17 Guangdong strains and 26 global reference strains.Ks rates and Ka rates of HA genes were 2.06×10-3～2.23×10-3 Nt/Year and 1.05×10-3～1.21×10-3 Nt/Year during 2007～2010,while the velocity of HA1 evolution of Ka was 3.13 times than that of HA2 evolution.Compared with HA of vaccine strain A/Perth/16/2009,the genetic homologies of Guangdong strains in 2009 reached to 98.8%～99.7% and of Guangdong strains in 2010 reached to 98.0%～98.4%.There were some amino acid substitutions in five epitope regions of HA1 during 2007～2010,especially in B region(N160K) and D region(K174R/N);the K189E/N/Q and T228A in RBS(receptor-binding site) occurred in 2010 as two glycoproteins sites substituted impacted on the HA1 antigenicity.The antigenicity of epidemic H3N2 strains in 2010 was to some degree different that of the vaccine strain A/ Perth/16/2009.According to that there were variations of B and D epitopes and two sites of RBS and two glycoprotein in Guangdong H3N2 HA1 genes,WHO/CDC should recommend new representative strains during 2011～2012 influenza seasons if H3N2 HA genes further evolve in the near future.