Study On Genetic Evolution Analysis Of Four Isolates Of Highly Pathogenic Avian Influenza Viruses H5N1 Subtype Isolated From Tiger

In 2004, four H5N1 subtype Avian Influenza viruses (AIV) were isolated from tigers in a zoo of Huabei. The IVPIs of all the four viruses were 3.0, so they were highly pathogenic avian influenza virus (HP AIV). For all eight viral genes of the four H5N1 AIVs, the full coding sequence was amplified with specific primers from the noncoding sequence of each gene segment. Other isolates of H5N1 AIV from 1996 to 2006 were used for sequence alignment. Sequence analysis of the hemagglutinin (HA) genes showed that the four viruses possessed an HA cleavage site sequence identical to other H5N1 subtype HP AIVs. The HA cleavage site sequence of T1 virus showed mutation from R to G at position 3 (at the position 339 of the amino acid sequences). The amino acids at positions 98,133,136,137,153,183,186,190,194,226 and 228 of RBS of all the four viruses were conserved, and the amino acids at position 155 were different. T1 virus was R and the others were G. The amino acid sequences analysis of the NA protein of the four viruses exhibited a 20-amino acid deletion at the stalk region. The amino acid sequences analysis of the NS gene showed that the NS gene of four viruses possessed deletion of the five amino acid residues"AIASS"at the position 80～84 of the NS protein.Phylogenetic sequence analysis of all eight genes showed that the four viruses were H5N1 subtype HP AIV. The four viruses clustered in the same branch, and had very high genetic relationship. The HA gene had the highest identification with the 01GD virus, 04HB virus and 03Kor virus. The Phylogenetic sequence analysis of all eight genes showed the four viruses were recombinant virus.To sum up, the four viruses were H5N1 subtype HPAIV, and had the ability to spread in the mankind, so should be prevented and cured. The four viruses were recombinant virus, so they could be further studied for vaccines.