The cDNA of HA gene of H9N2 avian influenza isolate was amplified,cloned and then sequenced.The result of its sequence analysis shows that cDNA of HA gene is composed of(1 683 bp) nucleotides,encoding for 560 amino acids.The sequence of the amino acids is R-S-S-R,typical of lowly pathogenic avian influenza.There are 7 potential glycosylation sites in the influenza virus isolate,the amino acids of the receptor-binding site are YWTNVLY,the amino acids of the left edge of receptor-binding site are NGQQG,and th...