Evolutionary characteristics of polymerase PA, PB1, and PB2 genes of novel influenza virus A/H1N1 in 2009 pandemic / 第二军医大学学报

ABSTRACT

Objective: To elucidate the evolutionary characteristics of polymerase PA, PB1, and PB2 genes of the novel influenza virus A/H1N1 in 2009 pandemic. Methods: The sequences of the PA, PB1, and PB2 genes of the novel H1N1 strains in 2009 pandemic, and the reference sequences of human, swine, and avian influenza viruses isolated during different years at different locations were retrieved from NCBI. Molecular Evolutionary Genetics Analysis version 4.0 (MEGA4.0) software was employed to align and blunt nucleotide sequences, construct phylogenetic tree, deduce and align PB2 protein sequences, and the results were compared between the novel A/H1N1 and each of the reference strains. Results: The sequences of the PA, PB1, and PB2 genes of 2009 novel A/H1N1 strains isolated from different locations shared a high homology and clustered in a unique new clade, and were close to the swine influenza 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 in 2005 (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 were glutamic acid (Glu), which was the same as that in the avian influenza virus in Iowa State of USA in 2005 (DQ889682), and was different from those of the reference sequences of human A/H1N1 strains isolated from 1918 to 2008, which were lysine (Lys). Conclusion: The 2009 novel A/H1N1 virus might be originated from the human A/H1N1 strains isolated in 2005 in Iowa State of America (A/Iowa/CEID23/2005/H1N1), and the polymerase gene of the novel H1N1 virus might re-assort with avian A influenza virus.