Development of a competitive chemiluminescence immunoassay using a monoclonal antibody recognizing 3B of foot-and-mouth disease virus for the rapid detection of antibodies induced by FMDV infection

Background Foot-and-mouth disease (FMD) is a devastating animal disease. Anti-non-structural protein (NSP) antibody detection is very important for confirming suspected cases, evaluating the prevalence of infection, certifying animals for trade and controlling the disease. Methods In this study, a competitive chemiluminescence immunoassay (3B-cCLIA) was developed for the rapid detection of antibodies against NSPs in different species of livestock animals using the monoclonal antibody (mAb) 9E2 as a competitive antibody that recognizes NSP 3B. Results The cut-off value (50%), diagnostic sensitivity (Dsn) (97.20%, 95.71%, and 96.15%) and diagnostic specificity (Dsp) (99.51%, 99.43%, and 98.36) of the assay were estimated by testing a panel of known-background sera from swine, cattle and sheep, respectively. The accuracy rate of the 3B-cCLIA was further validated and subsequently compared with that of two commercial diagnostic kits. The early diagnostic results showed that antibodies recognizing NSPs developed later (approximately 1–2 days) than antibodies recognizing structural proteins. Furthermore, anti-NSP antibody presence in animals vaccinated multiple times (false positives), especially cattle and sheep, was confirmed, and the false-positive rate increased with the number of vaccinations. Conclusions These results indicate that the 3B-cCLIA is suitable for the rapid detection of antibodies against FMDV NSP 3B in a wide range of species.