Development of an indirect ELISA against Orf virus using two recombinant antigens, partial B2L and F1L

Abstract

Abstract Background Orf is a highly contagious viral disease affecting goats and sheep. It is caused by Orf virus (ORFV) and has caused severe economic losses to the global goat and sheep industry. Therefore, it is particularly important to develop a convenient, rapid and low-cost diagnostic method for ORFV. Methods In this study, an indirect ELISA method for recombinant proteins based on truncated dominant antigenic epitopes of the B2L and F1L genes of ORFV was established. Results The sequences from aa208 to aa378 encoded by the B2L gene and sequences from aa2 to aa182 encoded by the F1L gene were selected by DNASTAR software analysis and intercepted as the major fragments of the ORFV double gene fusion. The method specifically detects anti-ORFV antibodies and does not cross-react with positive sera for other common goat pathogenic bacteria antiserum. ORFV-positive sera were still positive after 1:512 dilution, with an intra-batch coefficient of variation (CV) between 7.1% and 9.5% and an inter-batch CV between 5.0% and 7.6%; 62.55% (152/243) of immunized goat serum samples tested positive, and 14.44% (26/180) of nonimmunized goat serum samples were positive. Conclusion These results show that the B2L-F1L-ELISA antibody assay established in this study has good specificity, sensitivity and reproducibility and provides a technical tool for clinical ORFV serum antibody detection and epidemiological investigation.