Genome Properties And Phylogenetics Of AIV H2N2 And H3N8 Subtype Strains From Mallards

Avian influenza(AI) rapidly infects poultry and causes multiorgan systemic disease, that is caused by influenza A virus. It leads to high rate of morbidity and mortality and led much economical losses when it breaks out in various countries. Avian influenza viruses (AIV) are widely distributed on wild birds, the particularly natural reservoirs of avian influenza virus are wild waterfowls, which play an important role in spreading. The sequencing and biological characteristics analysis for a H2N2 AIV [A/Mallard/SanJiang/137/2006(H2N2)] and a H3N8 AIV [A/mallard/SanJiang/359/2007(H3N8)] isolated from Sanjiang natural Reserve in this study.In this report, the isolate A/Mallard/SanJiang/137/2006(H2N2) and A/mallard/SanJiang/359/2007(H3N8) were propagated in specific pathogen free(SPF) chicken embryo. Primers were designed and synthesized according to the relevant nucleotide sequences in GenBank, which were used of amplifying the full-length genes. Reverse transcription-polymerase chain reaction (RT-PCR) was used to amplify the full-length cDNAs of the AIVs. Thereinto, PB1 and PB2 genes were all divided into two fragments to amplified. The nucleotide sequences and their deduced amino acid sequences were compared and analyzed for the homology and phylogenetic relationships between the isolated strains A/Mallard/SanJiang/137/2006(H2N2)& A/mallard/SanJiang/359/2007(H3N8) and some other isolated strains of H2N2&H3N8 subtype by the Lasergene Sequence Analysis Paekage. The panorama phylogenetic trees of H2 and H3 genes of AIV and the phylogenetic trees of the other genes were drawn. Sequence analysis results showed that all of the eight segments of the two AIVs contained completed open-reading-frames and5'-3'-untranslated regions. Analysis of the results of homology comparison and phylogenetic relationships indiacted that isolate A/Mallard/SanJiang/137/2006(H2N2) & A/mallard/SanJiang/359/2007(H3N8) can be classified into Eurasian lineage. This presumes that the migratory birds play a role in the characteristic property of the viruses isolated Sanjiang.Beeause there were no or few about the H2N2 and H3N8 subtype AIV to be isolated from wild waterfowls to report in China, the results of molecular clone and analysis of the entire genes of the isolated strains A/Mallard/SanJiang/137/2006(H2N2) & A/mallard/SanJiang/359/2007(H3N8) will have great value for the researches of avian influenza, especially for the researches of perpetuation status of AIV among wild waterfowls and the researehes of molecular epidemiology of avian influenza.