A novel multi-epitope recombinant protein for diagnosis of African swine fever

Abstract Background: African swine fever(ASF) is an acute, severe and highly fatal infectious disease of pigs. The disease spreads rapidly, causing huge economic losses to the pig industry in infected areas. The structural proteins p30 and p54 in African swine fever virus(ASFV) have been verified as diagnostic antigens.Methods: In this study, we constructed a novel multi-epitope fusion antigen gene based on P30 and P54 proteins, induced expression in a prokaryotic expression system and analyzed the reactivity of the recombinant fusion protein. The purified recombinant protein m35 was used as the coating antigen to establish an indirect enzyme-linked immunosorbent assay (ELISA) detection method for ASFV. 116 serum samples and positive sera of other swine diseases were detected by indirect ELISA.Results: Our results indicate that the m35 gene fragment with a length of 558bp was successfully constructed. SDS-PAGE and Western Blotting analysis showed that the protein had a band at 22kDa, proving its good reactogenicity. ROC analysis was performed to validate the assay, the area under the ROC curve is 0.9738 (95% confidence interval, 0.9336 to 1.014), and does not cross-react with other swine diseases.Conclusion: Our results show that its sensitivity and specificity were highly accurate. It is feasible to use this recombinant protein as a diagnostic antigen to distinguish ASFV infection.