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 effective diagnostic methods for swine influenza virus H9N2 subtype, the NS1 gene of swine influenza virus H9N2 subtype was amplified 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 was purified by Ni-NTA and identified by western-blotting. An indirect enzyme-linked immunosorbent assay (ELISA) was used to analyze the antigenicity of the recombinant protein. The recombinant protein of NS1 was about 26 kD. The Western-blotting test showed that the recombinant protein reacted specifically with positive sera. The results of the ELISA test showed that the recombinant protein had good antigenicity.