2009年新型甲型H1N1流感病毒聚合酶编码基因进化分析

目的:探讨2009年新型甲型流感病毒(A/H1N1)聚合酶PA、PB1和PB2编码基因的进化规律。方法:从NCBI流感病毒基因数据库下载2009年新型甲型H1N1流行株的PA、PB1和PB2聚合酶编码基因序列以及人、猪和禽流感病毒相应的参考序列,采用Molecular Evolutionary Genetics Analysis version 4.0（MEGA4.0）软件比对和修剪此次流行株的代表序列及所有参考株序列并构建系统树,再比对和修剪此次流行株的代表序列及人A/H1N1病毒各年代(1918~2008年)参考序列并构建系统树,同时比对此次流行株的代表序列及人A/H1N1各年代(1918~2008年)参考序列编码PB2蛋白的氨基酸序列。结果:不同地区分离的2009年新型甲型H1N1流感病毒的聚合酶PA、PB1和PB2编码基因均具有高度同源性,并聚集在一个独特的进化支上,与猪流感病毒对应基因接近。三者均与2005年美国爱荷华州分离的人A/H1N1病毒基因(A/Iowa/CEID23/2005/H1N1)具有高度的相似性。2009年新型甲型H1N1流感病毒、2005年美国爱荷华州流行的H1N1 (DQ889682)病毒PB2蛋白第627位氨基酸与禽类流感病毒相同,均为谷氨酸,而与其他人A/H1N1 (1918~2008年)病毒的赖氨酸不同。结论:2009年新型甲型H1N1流感病毒聚合酶基因可能来源于2005年美国爱荷华州分离的人A/H1N1病毒,禽流感病毒可能参与了聚合酶基因的重排过程。

Evolutionary characteristics of polymerase PA,PB1,and PB2 genes of novel influenza virus A/H1N1 in 2009 pandemic

Objective: To elucidate evolutionary characteristics of polymerase PA, PB1 and PB2 genes of the novel H1N1 influenza A virus (A/H1N1). Methods: The sequences of PA, PB1 and PB2 genes of the novel H1N1 strains, and the reference sequences of human, swine, and avian influenza viruses isolated from different years and different locations were retrieved from GenBank. MEGA 4.0 computer software was employed to align and blunt nucleotide sequences, construct phylogenetic tree, deduce and align protein sequences. Results: The phylogenetic analyses of the polymerase genes revealed that novel H1N1 viruses had a high homology and clustered in a unique new clade, and close to swine H1N1 viruses. The PA, PB1 and PB2 genes of the novel H1N1 viruses had a high similarity with the corresponding sequences of a human H1N1 strain isolated in Iowa State of USA (A/Iowa/CEID23/2005/H1N1). Alignments of the deduced protein sequences showed that the 627th amino acid of PB2 of the novel H1N1 strains and A/Iowa/CEID23/2005/H1N1 was glutamic acid (Glu), which was identical to avian influenza virus, while this amino acid point in the reference sequences of the other human A/H1N1 strains isolated from 1918 to 2008 was lysine acid (Lys). Conclusion: the polymerase sequence analysis revealed indistinguishable nucleotide sequences and phylogenetic clustering, indicating the same source of infection. The human H1N1 strains isolated in 2005 in America (A/Iowa/CEID23/2005/H1N1) is likely to be a mediator during evolutionary process of this novel H1N1 virus. The Lys-to-Glu transition at the 627th site of PB2 indicated that novel H1N1 strains might partially re-assort with the gene of avian influenza.