THE PBl AND PB1-F2 GENES OF THE INFLUENZA VIRUS A/H5N1 STRAIN (A/CKAaETNAM/HG4/2005) AND ITS COMPARATIVE ANALYSIS WITH THOSE ISOLATED DURING 2004 - 2007 EV THE MEKONG DELTA REGION
Keywords:Avian influenza A/H5N1, nucleotide/amino acids, identity, homology, PBl, PB1
AbstractThe entire PBl gene of an avian influenza isolate collected from a chicken in Hau Giang province (designated as A/CkA^ietnam/HG4/2005) was obtained, completely sequenced, and analyzed for identity/homology with those strains available during 2004 - 2007 in the Mekong Delta region. As results, the entire PBl gene obtained fi:om the A/CkA^ietnam/HG4/2005(H5Nl) strain is 2274 bp, encoding for the PBl polypeptide of 757 amino acids. The 2274 bp is the size of all the avian influenza A/H5N1 strains belonging to the Guangdong sublineage, invariable since the formation ofthe clade 1.0 (1997). PBl has 11 nucleotide and 5 amino acid variations in comparison to those isolated in the Mekong Delta region during 2004 - 2007. The PB1-F2, enclaved in the PBl nucleotide frame from nucleotide 95 to 367, coding 90 amino acids. Asparagin
amino acid (N) at the 66' site in the PB1-F2 is unchanged in all the strains isolated in the Mekong Delta region during 2004 - 2007 so far in this study. The identity ofthe PBl gene of A/Ck/Vietnam/HG4/2005 is 97% for nucleotide at the lowest and 100% at the highest level; the homology is varied 98 - 99%»for amino acid (protein P&l) and 96 - 98% (protein PB1-F2). All 18 sUains isolated in the Mekong Delta region belong to clade 1.0 of the Guangdong sublineage.