Molecular and phylogenetic analysis of haemagglutinin sequences from influenza B isolates in the influenza outbreaks in Hebei Province in 2006

Objective In order to study the characteristics of HA1 gene of influenza B isolated from the influenza outbreak in Hebei Province in 2006,and to elucidate the relationship between the influenza epidemic/outbreak and the variation of HA1 region of the virus.Methods The viruses were isolated and propagated by MDCK.RNAs were extracted and their HA1 genes were amplified by reverse transcription polymerase chain reaction(RT-PCR).The purified PCR products were sequenced.The data obtained were analyzed with the software DNAStar.Results The influenza B viruses isolated from the influenza outbreak in Hebei province during 2006 are Victoria like strain,is different from the B/Shanghai/361/2002,the later is Yamagata-like-virus,but being similar to the epidemic isolates.Comparing to the B/Hong Kong/330/2001 virus,they had an identity of 96.4%～96.8% in nucleotide sequence,and far away from B/Hong Kong/330/2001 in phylogenic tree,6～7 variant amino acids were found locating in determinant sites.Conclusions The antigenic drift in HA1 region of the influenza B viruses isolated from the outbreaks and the influenza surveillance in Hebei Province in 2006 are similar,which is the fundamental cause of the influenza outbreak and form a new variant.