Characterization Of H₆ Subtype Avian Influenza Virus In Southern China

Influenza virus exists widely in nature with numerous of subtypes, and high frequency variation characteristics, which can infect all birds and parts of mammals. For understanding fully biological characteristics of the H6 subtype avian influenza virus in southern China from 2008 to 2009, here are 23 representative strains of H6 subtype virus which were analyzed systemically. Firstly,the results of antigenicity analysis showed that they were roughly divided into six antigenic subgroups, and there were significant differences amongst subgroups. Then,the results of genetic evolution analysis indicated that the origin of genes was discrepant. Many strains were reassorted with H5, H7 or H9 and other subtypes viruses from surrounding regions or countries, even shared higher homology of nucleotides with human and swine influenza viruses. It was bound to increase the the biological characteristics diversity of H6 subtype of avian influenza virus in southern regions. Eventually, we estimated the infection and virulence of 6 stains on SPF chickens. It was found that chickens infected by 3 of 6 strains showed seroconvertion.Importantly,one of these(DK/HB/061/08) owned higer replicate ability in respiratory tract, and can infect cohabitated chickens.This findings suggested that partial H6 subtype of avian influenza virus crossed the species barrier increasingly and acquired the ability of infection from waterfowl to terrestrial poulty,and spreaded quickly by horizontal transmission.Through the analysis of all genes sequence in 23 strains and the assessment of pathogenicity on chickens infected with 6 viruses, it was provided theoretic support to understand the genetic evolution and pathogenicity of H6 subtypes avain influenza viruses in the partial regions of China. Based on it, we estimated the influence to poultry production, and understood the influence of recombination and variation to highly pathogenic avian influenza virus, furtherly for prevention and integrated control of avian influenza in China...