2009-2011年广东省甲型H1N1流感病毒血凝素基因的进化特征

Molecular evolution of HA1 in pandemic HIN1 influenza viruses isolated in Guangdong during 2009 to 2011

目的了解2009--2011年广东甲型H1N1流感病毒血凝素基因的HA1进化特征。方法选取广东甲型H1N1流感病毒83株，提取病毒RNA，经RT—PCR反应扩增HA1并测序，测定的序列用生物信息软件分析，与GenBank中相关序列比较，并对推导的编码氨基酸序列进行进化分析。结果2009--2011年广东甲型H1N1流感病毒HAl基因的进化速率是5．2×10^-3，高于人季节性H1N1病毒；变异氨基酸多数位于HA蛋白表面，其中部分位于抗原决定簇；在两例死亡病例分离株HA1的第222位氨基酸发生D222G／D222N变异。结论遗传进化分析表明，甲型H1N1流感病毒发生了一定程度的变异，造成2011年初在广东的再次流行。HA1的第222位氨基酸变异可能与疾病的严重程度有关。

Objective To understand the evolutionary characterization of hemagglutinin （HA） gene of pandemic H1N1 influenza virus in Guangdong during 2009-2011. Methods We selected 83 pan- demic H1N1 strains isolated in Guangdong during 2009-2011. The HA1 genes were sequenced and analyzed comparatively by Bioedit 7.0 and MEGA 4.0. Results The evolutionary rate of HA1 gene of pandemic HI N1 and seasonal H1 N1 viruses was 5.2×10-3 substitutions/site/year, higher than that of seasonal H1N1 viruses. Most amino acid changes in HA1 molecules accumulated on the surface of the molecule and were partly located in antigenic sites. Two fatal infections were detected with a mutation at HA residue 222, in one virus with a change D222G, and in one virus D222N. Conclusion The phylogenetic analysis demon- strates that the influenza epidemic in Guangdong at the beginning of 2011 are due to occurrence of genetic changes of pandemic H1N1 virus. The amino acid change at residue 222 of the HA1 are likely to be associat- ed with severe or even fatal illness.