Analysis on Characteristics of HA1 Gene of Influenza H3N2 Isolated from Jilin Province during 2007-2008

Objective To analyze the characteristics of HA1 gene of influenza H3N2 isolated from Jilin province during 2007-2008,and elucidate the relationship between the influenza epidemic and the variation of HA1 region of the virus.Methods The viruses were isolated and propagated by MDCK cell.RNAs were extracted and their HA1 genes were amplified by reverse transcription polymerase chain reaction(RT-PCR).The purified PCR products were sequenced.Results ①The pandemic strains of influenza H3N2 isolated in Jilin province 2007-2008 had 98.9%-100% identity of nucleotides.Compared with A/Wisconsin/67/05 vaccine strain recommended by WHO,10-14 amino acid had changed,and there was one more glycosylation site at 122nd site.②The virus isolated in Changchun city in November and December located in two different branches of the phylogenetic tree.③The influenza strains of eight regions formed two clusters in the phylogenetic tree.Conclusion Compared with A/Wisconsin/67/05,The viruses of influenza H3N2 in Jilin province 2007-2008 occur evident antigenic drift in HA1 region,and the influenza pandemic strains have some difference in different times and regions as well.