New approaches for post-vaccination surveillance of foot-and-mouth disease

Foot-and-mouth disease (FMD) is a contagious and important transboundary disease of cloven-hoofed animals and ruminants. In ruminants, an animal is considered as a foot-and-mouth disease virus (FMDV) carrier if a live FMDV/FMDV RNA is obtained from the oro-pharyngeal fluid (OPF) beyond 28 days after infection. These carrier animals may pose a risk for causing outbreaks in healthy animals. Moreover, it is important to conduct serosurveillance to know the virus circulation. In the present study, an ELISA was developed using field samples to detect FMDV specific secretory IgA antibodies. These samples were also tested for the presence of FMDV RNA using quantitative real-time PCR (qRT-PCR). It was found that more carrier animals were detected by IgA ELISA in comparison to qRT-PCR. Thus, IgA ELISA is an important tool to detect FMD carriers. An ELISA based on detection of antibodies against FMDV 2B non-structural protein (NSP) was also used to confirm the results obtained from screening of 3AB3 NSP ELISA. These two new approaches (IgA ELISA and 2B ELISA) form important tools for detection of carriers and virus circulation, respectively, during FMD eradication program. Keywords: foot-and-mouth disease virus; carriers; IgA; 2B non-structural protein; 3AB3 non-structural protein.