Development and optimization of a double antigen sandwich ELISA detecting for Senecavirus A antibodies based on VP2...

Senecavirus A (SVA) is an emerging viral pathogen that threatens the global swine industry significantly. The major clinical symptoms of SVA-infected animals are vesicular lesions, but various diseases can cause the same symptoms, which makes it difficult to distinguish SVA from other vesicular diseases clinically. The absence of an effective and safe vaccine necessitates the development of a simple, specific, and sensitive serological detection method for SVA antibodies. The VP2 protein of SVA, characterized by high immunogenicity and sequence conservatism, is an essential target for serological diagnosis. In this study, a double-antigen sandwich enzyme-linked immunosorbent assay [ELISA (DAgS-ELISA)] based on VP2 protein expressed by Escherichia coli was established for SVA antibody detection. With a cut-off value of 0.237, this assay demonstrated outstanding performance, showing high sensitivity and sharp specificity, which is manifested in the absence of cross-reaction with classical swine fever virus (CSFV), African swine fever virus (ASFV), pseudorabies virus (PRV), and porcine reproductive and respiratory syndrome virus (PRRSV), and foot-and-mouth disease virus (FMDV) serotype A and O. Additionally, the repeatability of the method is remarkable, as shown by the coefficients variation (CV) of both the intra- and inter-assay below 10%. By detecting 166 clinical sera, it was found that the kappa value of the DAgS-ELISA was 0.78 compared with that of the virus neutralization test (VNT), indicating a high level of consistency. In general, this method has high sensitivity, sharp specificity, remarkable repeatability, sound consistency, and low cost, making it a reliable and effective tool for detecting SVA antibodies.IMPORTANCESVA has rapidly become prevalent in many countries, and its outbreaks have threatened the global swine industry significantly. The major clinical symptoms of SVA-infected animals are vesicular lesions that are similar to other vesicular diseases, making it difficult to distinguish SVA. Currently, no commercial vaccines are available for SVA; therefore, effective diagnosis of SVA infection is vital for its prevention and control. In this study, VP2 protein of SVA was expressed by E. coli, and a double-antigen sandwich enzyme-linked immunosorbent assay [ELISA (DAgS-ELISA)] for SVA antibodies detection was successfully established based on the VP2 protein. The DAgS-ELISA has a high sensitivity, sharp specificity, remarkable repeatability, sound consistency, and low cost for detecting SVA antibodies. Therefore, the DAgS-ELISA established in this study may be a reliable and effective tool for detecting SVA antibodies and may be used to strengthen the monitoring and prevention of SVA epidemic in the long run.