Phyletic evolution and molecular variation of influenza B viruses in Shenzhen, 2009

Objective To study the phyletic evolution and molecular variation of influenza B viruses in Shenzhen in 2009. Methods The time distributions of the isolates influenza B viruses were analyzed. The phyletic evolution and molecular variation analysis of their HA1 genes were conducted by MEGA program. Results The time distributions of isolates of influenza B viruses indicated that the viruses circulated from January to October in 2009, which peaked during March-May. The virus in clade D of Victoria lineage was predominant. Compared with the viruses of influenza vaccines for 2008 - 2009 season, partial mutations of antigenic determinants in HA1 were detected in Victoria and Yamagata lineages. Conclusion The results indicated that the long time circulation of influenza B viruses was found in Shenzhen in 2009. The partial mutations detected in two lineages didnt resulted in the emerging of new circulating virus strains