In order to obtain the CSFV E^rns protein for the application in ELISA,the gene sequence of the E^rns protein was optimized according to the codon bias of Spodoptera frugiperda cells.Firstly,the gene was inserted into the recombinant vector pFastBacl-gp67,which contains the gp67 signal peptide sequence.Secondly,the resulting plasmid pFastBacl-gp67-E^rns was transformed into the DH10Bac competent cells to get the recombinant bacmid through blue-white screening.Thirdly,the recombinant Bacmid-E^rns was transfected into the sf21 cells to generate the recombinant baculovirus.Finally,the sf21 cells were infected with the recombinant baculovirus.At three days post infection, culture supernatant was collected.The E^rns protein was purified by nickel-affinity chromatography.The expression level and purity of the protein were identified using SDS-PAGE and Western blot analysis.The glycosylation pattern of the purified Erns protein was analyzed using PNGase F.And the indirect ELISA was carried out to analyze the antigenicity of the protein.Consequently,the recombinant pFastBacl-gp67-E^rns plasmid was generated.And the Bacmid-E^rns was obtained using blue-white screening.The recombinant baculovirus was used for large-scale expression of E^rns.The secretory expression of Erns was achieved using signal peptide.It was shown that the purified E^rns was of high purity.And the Erns was glycosylated properly.The purified E^rns protein could be specifically recognized by the CSFV positive serum,indicating that the purified protein was of high activity.