Abstract：A pair of primers specific to NS gene of H5N1 subtype and H3N2 subtype avian influenza virus isolates from Nanning poultry market between 2004 and 2005 was designed on the basis of the NS gene sequence from GenBank. The cDNA of the NS gene was amplified by RT-PCR and cloned into pMD18-T vector,and nucleotide sequences of the NS gene of the three isolates were 855 bp,834 bp and 837bp in length respectively. The sequence analysis showed that the nucleotide homologies between the two isolates of H5N1 subtype was 95.3 %,however,those between H5N1 subtype and H3N2 subtype were from 94.0% to 94.1%. The NS gene of the H5N1 isolates had 15 nucleotide deletions,which was typical of highly pathogenic H5N1 viruses isolated in various countries from 2000. Comparison with the strains from Guangdong,HongKong,YuNNan,Hunan,Hubei and South Asia indicated that the nucleotide homology were from 70.5 % to 97 %. Phylogenetic analysis showed that three isolates were situated in sublineages A,but they formed different distinct little sublineages,A/ DK/GX/1566/04(H3N2) showed closer relationship with virus islaoted from Guangdong and HongKong from 2001 to 2003. A/ Goose/ GX/ 737/05(H5N1) and A/ Goose/ GX/ 2775/05 (H5N1) had high aligment located in the same lineage together with virus isolated from southeast region of China and some areas of Asia including Korea,Vietnam and Thailand after 2003.
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