Molecular and Phylogenetic Analysis of Haemagglutinin Sequences From Influenza B Isolates in Hebei Province in 2006

Objective To analyze the characteristics of HA1 gene of influenza B isolated from Hebei Province in 2006, and to 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. The data obtained were analyzed by the software DNAStar. Results The influenza B viruses from Hebei Province in 2006 were Victoria like strain, which were different from the B/Shanghai/361/2002, Yamagata-like-virus. Comparing to the B/Hong Kong/330/2001 virus, they had an identity of 96.5%～97.2% in nucleotide sequence, which were far away from B/Hong Kong/330/2001 in the phylogenic tree, and six variant amino acids were found locating in antigenic determinant sites. Conclusion The influenza B viruses in Hebei Province in 2006 occurred evident antigenic drift in HAI region, which caused the influenza B epidemic and outbreak in Hebei Province during the period of 2006. They are new variants and should be paid close attention.