The exon sequences of NSgene of H9N2influenza virus isolated from Henan were obtained by cloning and sequencing to study the evolution of NS gene of H9N2subtype influenza virus in Henan.By comparing the NSgene sequence with those of previously reported strains,sequence homology analysis showed that NS gene of H9N2influenza virus isolated from Henan belong to one group represented by F98from Shanghai.The evolution relation of H9N2influenza virus isolated from Henan was determined by evolution analysis in the...