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Abstract The eight full-length genes of H9N2 subtype avian influenza virus A／Chicken／Zhejiang／HJ／2007(H9N2) were amplified by reverse transcription-polymerase chain reaction (RT-PCR),and then cloned to pMD18-T vector and sequenced. The sequenced result revealed that the hemagglutinin（HA）gene’s deduced amino acid sequence at the cleavage site of the HA protein was -PSKSSR*G-, which was match to the characteristic of low pathogentic avian influenza（LPAI）, which belong to the A/Quail/Hong Kong/G1/97 (H9N2) sublineage, not the same as most of the viruses belong to the A/Chicken/Beijing/1/94 (H9N2) sublineage.The neuraminidase (NA) gene had deletions at 63, 64 and 65 amino acids, which derived from the A/Chicken/Beijing/1/94(H9N2)[A/Duck/HongKong/Y280/97(H9N2)]sublineage.The nucleoprotein （NP） was similar with some H5N1 subtype influenza viruses which also isolated in Zhejiang Province, they all had near phylogenetic relationship. The matrix （M）protein was at one sublineage with A/Hong Kong/1073/99(H9N2) and A/Hong Kong/1074/99(H9N2), those two viruses infected two children in Hong Kong at 1999. The nonstructural （NS） protein was at one sublineage with H9N2 subtype swine influenza viruses isolated during the past few years, at one sublineage with A/Swine/Hong Kong/9/98(H9N2). However, the polymerase protein: the PB1 gene had 15 nucleotides（caatccgactttact）deletions from 33 to 47, which was first report had deletion 5 amino acids from four to eight in ORF. The PA gene and the PB1gene had familiar phylogenetic, which were near to the H5N1 subtype influenza viruses. But the PB2 gene didn’t show any immediate ancestor with the different avian influenza viruses used in the paper. Therefore, A／Chicken／Zhejiang／HJ／2007(H9N2) is product of natural reassortment from different influenza viruses sublineages.
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Received: 12 November 2008
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