Monoclonal antibody based competitive 3AB non-structural protein ELISA for detection of foot-and-mouth disease virus infection.

Foot and mouth disease (FMD) is one of the most infectious viral diseases of cloven-footed animals which cause devastating global economic losses. FMD virus (FMDV) specific non-structural protein (NSP) antibodies are indicative of a current or past infection with any of the seven FMDV serotypes(O, A, C, Asia1, SAT1, SAT2, SAT3). In the present study, a monoclonal antibody (MAb) was developed against recombinant FMDV NSP 3AB3 (r3AB3) via hybridoma system and applied in a competitive enzyme linked immunosorbent assay (cELISA) for NSP antibody detection. The newly generated MAb #FMDV3AB-2E4 was identified as an IgG1 isotype that specifically binds to NSP 3B. A cELISA termed FMDV3AB-2E4 cELISA was developed using r3AB3 as the antigen and the MAb. Percent inhibition (PI) cut-off of the cELISA was determined by receiver operating characteristics curve analysis of 202 known FMDV-positive and 730 negative serum samples from multiple species (cattle, buffalo sheep, goat, pig and deer). At the selected cut-off value of 45 PI the cELISA exhibited diagnostic sensitivity (DSn) of 95.54% and diagnostic specificity (DSp) of 98.36% at 95% confidence interval. Compared to commercial PrioCHECK FMD NS test the DSn was 93.54% and DSp was 97.46% for bovine and caprine sera (n = 446) obtained from naïve, FMDV-infected and vaccinated animals. Concordance rate of new cELISA and extensively used in-house r3AB3 indirect ELISA was 96.61% for test results of 3016 cattle sera collected across multi-locations in India. The species independent NSP antibody test developed would be a useful tool in FMD control efforts in India and other countries.