Validation of an r3AB1-FMDV-NSP ELISA to distinguish between cattle infected and vaccinated with foot-and-mouth disease virus.

Foot-and-mouth disease (FMD) is a highly contagious disease of cloven-hoofed livestock which has a drastic economic impact for affected countries. Although FMDV is distributed worldwide, many regional programs have been effective eradicating this agent. In Argentina, as in many other regions of South America, the combination of a systematic vaccination plan, together with an effective detection system capable of differentiating infection from vaccination, has been successful for eradicating this agent from the country. The properties of recombinant 3AB1 FMDV non-structural protein (r3AB1 FMDV-NSP), as a marker for the detection of antibodies to differentiate between cattle infected and vaccinated with FMDV, have been described previously. The goal of the present study was to validate the 3AB1 ELISA using a well characterized serum panel from Argentina (n=559) including eight national and one international reference sera. Overall, the 3AB1 ELISA demonstrated good feasibility, repeatability, reproducibility, analytical sensitivity and specificity, and accuracy. The results from the 3AB1 ELISA when compared with those obtained from the OIE index test (NCPanaftosa screening) showed a similar performance of both tests [diagnostic sensitivity=84% (C.I.=79-88%) and 80% (C.I.=75-85%), respectively; and diagnostic specificity=98.6% (C.I.=97-100%) and 95% (C.I.=91-98%), respectively]. The present work proposes the 3AB1 ELISA as an alternative to imported kits for FMD internal screening and transboundary sero-surveillance.