| To understand biological characteristics of the H6subtype avian influenza virus in recent years in China,from2008to2009, here are18representative strains of H6subtype virus isolated during the epidemiological survillence which were sequenced fully, genetic evolution analysis, genetic homology comparison, antigenicity analysis and genome analysis. Eventually, we estimated the pathogenicity and virulence by the infection of8stains on SPF chickens and BALB/c mice.The results of the genome analysis showed that all of the gene sequences contain complete gene sequence of ORF; Non-continuous were found in HA cleavage site amino acid sequence of multiple basic amino acids with a low Pathogenic influenza typical characteristics of the virus, and no deletion in the stalk region of NA. Then, the results of genetic evolution analysis indicated that the origin of genes was comprehensive. Many strains shared high similarity with H5, H7and other subtypes viruses from surrounding regions or countries, and minority strains not only located in the same evolution branch with other subtypes such as H1、H2、H3、H4、H13、H15but also shared higher homology of nucleotides with human and swine influenza viruses. the results of antigenicity analysis showed that they were roughly divided into seven antigenic subgroups, and there were significant differences amongst subgroups. From the result of pathogenicity experiment it was found that chickens infected by5of8strains showed seroconvertion. and one of these(DK/HB/471/10) owned higer titers in respiratory tract. But there were7of8strains can replicate efficiently in the lung of BALB/c mice, and only3(DK/HN/393/09、GS/GD/256/09and DK/HN/315/10) of7can be detected in turbinate, but the body weight change in the14days post-infection were barely obvious.Come to a conclusion that AIVs of H6subtype have wide spread rearrangement between different subtypes, and some virus strains have acquired the ability to infect poultry even BALB/c mice in the evolutionary process. |
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