Analysis on the HA gene Characteristics of Novel Influenza A(1H1N1) Virus

Objective:To understand the genetic characteristics of novel influenza A(H1N1) viruses circulated in 2009.Methods: 3 pairs of primers were designed to amplify the HA gene of 9 novel influenza A(H1N1) viruses detected in Tianjin.Then PCR products were sequenced,and were spliced together to obtain the complete HA gene.Phylogenetic and characteristic analysis of HA gene were performed.Results: All the HA sequences of 9 novel influenza A(H1N1) viruses were amplified successfully.After splicing,the complete HA gene was 1778bp in length.Phylogenetic tree was constructed using 1702 bp in open reading frame.HA genes of novel influenza A(H1N1) viruses gathered together with classical swine influenza A(H1N1).The high identities(98.8%-99.6%) of HA gene were observed between novel influenza A(H1N1) isolated in Tianjin and WHO recommended vaccine strain A/California/07/2009(H1N1) and China representative strain A/Sichuan/1/2009(H1N1).The amino acid sequences on HA domain protein were similar to A/California/07/2009(H1N1) and A/Sichuan/1/2009(H1N1),but still have 4 and 3,respectively,amino acid sequence differences.Conclusion: HA gene of novel influenza A(H1N1) viruses originated from classical swine influenza viruses.The variation of HA gene in novel influenza A(H1N1) viruses was not so significant,but we still have to surveillance the variation closely.