Genetic analysis of the nonstructural gene (NS1) of H9N2 avian influenza viruses isolated in China
Li, J-Li.; Chen, E-Lin.; Li, H-Ping.; Hao, C-Li.; Bi, D-Ren.; Wang, Z-Lin.
Bing du Xue Bao 24(3): 220-226
2008
ISSN/ISBN: 1000-8721 PMID: 18683560 Document Number: 619992
The nonstructural genes (NS1) of nine H9N2 subtype avian influenza viruses isolated from diseased chickens on different farms during1998-2005 were amplified by RT-PCR and completely sequenced. The nucleotide and deduced amino acid sequences of NS1 genes of these isolates were compared. The results showed that NS1 genes of all H9N2 isolates contained 654 bp and encoded 217 amino acids. The homologies of the nucleotide and deduced amino seguences of the isolates were 95.4%-99.8% and 93.6%-100%, respectively. Comparison of the amino acid sequences of NS1 proteins of these isolates with other H9N2 viruses demonstrated that NS1 proteins of the nine strains had a deletion of 13 amino acid residues at the carboxyl terminus, which may be the molecule mark of the isolates in mainland China. Phylogenetic analysis revealed that the NS1 genes of these isolates fell into the same lineage and belonged to allele A. Eight out of nine isolates belonged to the CK/SH/F/98-like lineage whileonly Ck/HN/A3/98 strain belonged to the Ck/HK/Y280/97-like linease. All the isolates were derived from Ck/BJ/1/94 strain which was the first isolate is mainland China in 1994. The results indicated that H9N2 subtype AIV appeared differentiation following the passage of time and the viruses belonging to Ck/SH/F/98-like acquired an epidemic spread advantage in chicken population in mainland China.