Comparative evaluation of bionote FMD NSP Ab and PrioCHECK® FMDV NS Ab ELISA kits for detection of foot-and-mouth disease virus non-structural proteins antibodies in SAT serotypes

Abstract Foot-and-mouth disease (FMD) is a highly contagious viral disease associated with serious economic challenges. Effective serological diagnostics are essential for managing the disease properly. Detection of antibodies against non-structural proteins (NSPs) of the FMD virus (FMDV) differentiates between infected and vaccinated animals. This study evaluated the comparative performance of the commercially established PrioCHECK ® FMDV NS Ab ELISA, used as the reference assay, and the newer Bionote NSP Ab ELISA for the detection of FMDV NSP antibodies in cattle exposed to Southern African Territories (SAT) serotypes. A total of 401 serum samples from the Agricultural Research Council, Transboundary Animal Diseases (ARC-TAD) biobank were tested using both assays. Linear regression analysis demonstrated a significant relationship between the percentage inhibition values generated by the two assays. A moderate, positive correlation ( r = 0.69, 95% CI: 0.61–0.74, p < 0.001) was observed between the two assays. Of the samples tested, 257 (64.09%) tested negative on both ELISAs, 94 (23.44%) tested positive on both, and 50 (12.46%) showed discrepant results. Among these, 38 were positive on Bionote FMD NSP Ab ELISA but negative on PrioCHECK ® FMDV NS Ab ELISA, while 12 were positive on PrioCHECK ® but negative on Bionote (χ 2 = 12.5, p = 0.0004). Using the PrioCHECK ® FMDV NS Ab ELISA as the reference assay, the Bionote FMD NSP Ab ELISA demonstrated a sensitivity of 88.7% (95% CI: 81.1–94.0) and specificity of 87.1% (95% CI: 82.8–90.7). Receiver operating characteristic (ROC) analysis identified an optimal Bionote cut-off value of 51.825%, corresponding to a maximum Youden’s index of 0.776. Cohen’s kappa coefficient for the ELISAs was calculated to be 0.7, indicating substantial agreement between the ELISAs. The findings demonstrate that the Bionote FMD NSP Ab ELISA performs comparably to the PrioCHECK ® FMDV NS Ab ELISA and may serve as a useful complementary assay for FMD surveillance programmes. The availability of an additional NSP ELISA may also support testing continuity during periods of reagent shortages or supply-chain disruptions.