Prokaryotic Expression of Truncated S1 Protein of Porcine Epidemic Diarrhea Virus and Production of Monoclonal Antibodies to Recombinant Protein

Monoclonal antibodies are known to have several applications in clinical diagnosis and therapy. In the present study, the truncated S1 gene, encoding the exterior of the viral spike protein of porcine epidemic diarrhea virus (PEDV), was subcloned into prokaryotic expression vector pET32a (+) and expressed as a recombinant protein in Escherichia coli BL21(DE3). Female BALB/c mice were immunized with the purified recombinant truncated S1 protein, and three monoclonal antibodies (MAb designated as E3, G8, and G9) against the truncated S1 protein obtained by hydridoma technique. Further characterization demonstrated that the three MAbs (E2, G8, and G9) belong to IgG1 subclass and have different affinities (G9 > G8 > E3). Furthermore, all of the three MAbs reacted with PEDV in the fluorescent antibody assay. Our study suggests that purified truncated S1 protein and the three developed MAbs could be useful in the development of a diagnostic assay for anti-PEDV antibodies and PEDV antigen, respectively.