Cloning of the full--length genome of H8N4 subtype avian influenza virus strain A/duck/Yangzhou/02/2005 and analysis of the sequences
An H8N4 subtype avian A influenza virus was isolated from the aquatic birds in some live bird markets when we surveyed the ecology of avian influenza in East China for more than four years and identified by specific RT-PCR. The eight full-length genes, including 5'and 3'ends of H8N4 subtype avian influenza virus （A/duck/Yangzhou/02/2005） were amplified by using the universal primers. The amplified segments were cloned into the pGEM-T easy vector, respectively. The results showed that each of the eight gene cDNA fragments contained the whole open reading frame of their own. The NA sequence of Dk/YZ/02/05 was analyzed and the result demonstrated that there had no 20 amino acids missing in 48-68 sites, and no residue lost in NS gene in 263 to 277 sites. The motif of HA cleavage site is P-S-V-E-P-R, which is the characteristics of low pathogenic AIV.