Cloning, Prokaryotic Expression, and Antigenicity Analysis of NS1 Gene of H9N2 Swine Influenza Virus

To obtain the NS1 gene of swine influenza virus H9N2 subtype expressed efficiently in E. coli, to develope the effectivediagnostic methods for swine influenza virus H9N2 subtype, the NS1 gene of swine influenza virus H9N2 subtype wasamplified by reverse transcriptase polymerase chain reaction (RT-PCR) and cloned into a prokaryotic expression vector,pET-28a(+), and overexpressed in E. coli BL21-DE3 after induction with 5 mmol L-1 lactose. The recombinant protein waspurified by Ni-NTA and identified by western-blotting. An indirect enzyme-linked immunosorbent assay (ELISA) wasused to analyze the antigenicity of the recombinant protein. The recombinant protein of NS1 was about 26 kD. TheWestern-blotting test showed that the recombinant protein reacted specifically with positive sera. The results of theELISA test showed that the recombinant protein had good antigenicity.