ABSTRACT
Abstract:One H5N1 subtype avian influenza virus, A/duck/Shandong/009/2008 (Dk/SD/009/08), was isolated from apparently healthy domestic ducks in some live bird market in East China during our epidemiological surveillance. To investigate the genetic composition, Dk/SD/009/08 was subjected to genome sequencing. The amino acid motif of cleavage site was "PLRERRRK-R/GL", which was consistent with the characterization of the HPAIV. According to the newest unified nomenclature system of H5N1, Dk/SD/ 009/08 was classified into Clade 2.3.4. The BLAST results showed that four gene segments (HA, NA, NP and NS) had the highest nucleotide identities with H5N1 subtype AIVs whereas the remaining four (PB2, PB1, PA and M) displayed the closest relationship with H9N2 subtype. Therefore, Dk/SD/009/08 might be a natural reassortant virus. The phylogenetic analysis further indicated that G1-like H9N2 subtype AIVs which was prevalent mainly in quails of Southern China might provide the internal genes for Dk/ SD/009/08.
