Abstract:
Objective To understand the epidemiological characteristics, evolution and antigenic drift of influenza A (H3N2) virus in Hubei province during 2010-2015. Methods The epidemic peaks were divided by using the positive rate of influenza A (H3N2) virus in Hubei during this period. Positive number, isolation number and phylogenetic trees of the virus were analyzed in every epidemic peaks, then amino acid substitution of antigen was analyzed by using substitution data and homology modeling structures of the HA protein of influenza A (H3N2) clade 3C.2a viruses. Results There were eight epidemic peaks during the variation of influenza A (H3N2) virus in Hubei during 2010-2015. The epidemic peak of influenza A (H3N2) virus would be influenced by epidemics of other influenza viruses. After the seventh epidemic peak, clade 3C.2a virus was most prevalent. Seven amino acid substitutions and their different structures were detected on three major epitopes of HA protein between clade 3C.2a and 3C.3a viruses. There were distinct structure difference in amino acid sites between 159Y-160T (3C.2a virus) and 159S-160K (3C.3a virus). Conclusion Evolution of influenza A (H3N2) virus occurred in Hubei during 2010 - 2015. It is necessary to strengthen the surveillance for the evolution and analysis of clade 3C.2a virus to facilitate the pathogenic and epidemiological study of influenza in Hubei.