Genetic Characteristics of HA1 Gene of Influenza A(H3N2) Virus Circulated in Simultaneous 2 Outbreaks in Nanning City

[Objective]To understand the genetic characteristics of influenza A(H3N2) virus circulated in 2 outbreaks in the different area of Nanning at the same time. [Methods]Viral RNA was extracted from the influenza A(H3N2) virus subtype isolated from MDCK,and was sequenced full-length hemagglutinin nucleotide,then the amino acid sequence was deduced.The analysis focused on the genetic characteristics of HA1 Gene. [Results]A total of 5 strains of influenza A(H3N2) virus subtype were isolated.The results of nucleotide and amino acid sequence demonstrated that the similarities of nucleotide and amino acid sequence compared with Northern Hemisphere vaccine strain A/Wisconsin/67/2005(H3)recommended by WHO in 2007 were 98.58%~98.89% and 96.96%~97.87% respectively,the number of alternative were 11~14 and 7~10,which involved 3 major antigenic sites. [Conclusion]The strains of influenza A(H3N2) virus subtype circulated in the 2 outbreaks had antigenic drift and virulence change.The characteristics of strains isolated from different areas were not quite similar,and the strains from 1 outbreak at different time were different in gene.