Development of a competitive ELISA for the detection of antibodies against the 3B protein of foot-and-mouth disease virus

Foot-and-mouth disease (FMD) is one of the most highly contagious and economically devastating diseases, that severely constrains the international trade of animals. Vaccination against FMD is a key element in the control of FMD. However, vaccination of susceptible animals raises critical issues, such as the differentiation of infected animals from vaccinated animals. The current study developed a reliable and rapid test to detect antibodies against the conserved, non-structural proteins (NSP) of the FMD virus (FMDV) to distinguish infected animals from vaccinated animals. A monoclonal antibody (mAb) against the FMDV NSP 3B was produced. A competitive enzyme-linked immunosorbent assay (cELISA) for FMDV/NSP antibody detection was developed using a recombinant 3ABC protein as the antigen and the 3B-specific mAb. Sera collected from naïve, FMDV experimentally infected, vaccinated carrier and non-carrier animals were tested using the 3B cELISA. The diagnostic specificity was 99.4% for naïve animals (cattle, porcine and sheep) and 99.7% for vaccinated non-carrier animals. The diagnostic sensitivity was 100% for experimentally inoculated animals and 64% for vaccinated carrier animals. The performance of this 3B cELISA was compared to four commercial ELISA kits using a serum panel established by the World Reference Laboratory for FMD at Pirbright. The diagnostic sensitivity of the 3B cELISA for the panel of FMDV/NSP positive bovine serum was 94%, which was comparable or better than commercially available NSP antibody detection kits. This 3B cELISA is a simple, reliable test to detect antibodies against FMDV non-structural proteins.