Isolation and Identification of Type A Swine Influenza Virus from Shandong Province and Sequence Analysis of HA Gene
Abstract: 10 influenza viruses were isolated from sicked pigs in different places of Shandong province from autumn of 2002 to spring of 2003. They were all identified as Influenza A virus of H9N2 subtype by National Influenza Research Center. The complete HA gene of one isolate Sw/SD/1/2003 (H9N2) was cloned and sequenced and compared with other H9N2 isolates of avian and swine in GenBank. The results indicated that the isolate Sw/SD/1/2003 (H9N2) was similar to Ck/GX/1999 (H9N2) and Ck/YN/2000 (H9N2 ) in HA gene; Sw/SD/1/2003 might come from an avian influenza H9N2 subtype according to the phylogenetic analysis of HA genes; the amino acid sequence at the HA cleavage site in Sw/SD/1/2003 is R-S-L-R-G, but the sequences of all other H9N2 subtypes of porcine isolates and avian isolates are R-S-S-R-G.