Characterization Of H3Subtype Avian Influenza Virus In China From2009to2013

To understand biological characteristics of the H3subtype avian influenza virus, we sequenced surface genes of60H3subtype AIV during the surveillance which are isolated from China since2009to2013.1analyzed representative strains of them to investigate the antigenicity, pathogenicity and genetic evolutionary relationship, for the comprehensive evaluation of H3subtype AIV on the effect of poultry production and prevention.The results of antigenicity analysis of22H3subtype AIVs revealed that they were roughly divided into4subgroups, and be of significant differences to reflect te antigenic diversity in China. By sequenced surface genes of H3subtype AIV which isolated from different periods and areas, we found that N2/N8are the main subtypes of neuraminidase, with some N1、N3、N6strains together. The result showed that NA genes have complicated origins. The who-genome-sequenced viruses indicated the discrepant origins. Except for NS and NA N8genes, the other genes belonged to Eurasian branch and were highly homologous with other subtypes AIV isolated in China or surrounding regions and countries, such as H1、H2、H4、H5、H6、H7、H9、H10、 H11and so on. Some individual gene segments were homologous with human, swine and equine origins, may be recombination. Genotyping results showed the complex and diversity of this subtype AIV. Eventually, the20whole-genome sequenced viruses were challenged in BALB/c mice to determine the infection and virulence. It was found that6out20viruses did not be of the ability of infection, and it was only limited in the turbinate and/or lung in viruses isolating in the14infected, but nonlethal at all, which suggested that H3subtype viruses did not get the ability to infect the whole body of mammals by now. In addition, we also estimated the pathogenicity and virulence by the infection of8strains on SPF chicken, the results showed that there were obvirous differences in shedding. Some infected chickens were able to shedding through the respiratory only, and some were able to shedding through the respiratory ad gastrointestinal tracts and had the ability to spread among chickens and the virus were restricted replication in trachea, kidney, appendix and lung in the infected chickens.The research systematically illustrate the biological diversity and genetic complex of H3subtype AIV in China, the viruses has complicated origins, significant antigenicity and multiple Genotype, makes it hard to prevent and control in the future. Although it has not yet get the infect the whole body of mammals, it may provide gene segments for HPAIV. The genetic complexity and diversity of viral origin also prompt us that epidemiological surveillance and characterization study has important practical significance.