Evolutionary characterization of HA1 gene of influenza A H3N2 viruses from 2003 to 2008 in Hebei / 中华疾病控制杂志

ABSTRACT

Objective To understand the genetic characterization of HA1 gene of influenza A H3N2 viruses circulated in recent years in Hebei.Methods Viral RNAs of 25 H3N2 strains were extracted and amplified by Reverse Transcription Polymerase Chain Reaction (RT-PCR).The products of PCR were purified and sequenced,and the sequences were analyzed though biometic software.Results Several amino acid substitutions located in antigenic sites or receptor binding sites were found more in the isolates than the current vaccine virus or the isolates from previous year.Amino acid substitution was found in 3,140,142,144,145,158,159,189,192,193,198,204,225,226 and 227 positions in the isolates during 2003-2008,more amino acid substitutions took place in antigenic determinant A,B and receptor binding site (RBS).New phylogenetic branches appeared continuously during 2003-2008.The H3N2 strains of the same year almost clustered in the same group on the phylogenetic tree.Conclusions Amino acid substitutions continuously occurred in the HA1 genes in influenza A H3N2 viruses isolated in Hebei from 2003 to 2008,it is meaningful to pay close attention to the HA1 variation in order to prevent and control influenza.