Foot-and-mouth disease (FMD) is stoutly and undeniably averred to be one of the highly contagious animal viral diseases leading to plenteous economic losses (Porphyre et al., 2018). It is one of the most annihilating infectious diseases victimizing the animal husbandry posing a major impediment to the livelihood security of the poor farming community. Even-toed placental mammals in the order Artiodactyla importantly cattle, pig, sheep and goat are susceptible to the disease. As per All India Report of 20th Livestock Census (2019) conducted by the Ministry of Fisheries, Animal Husbandry & Dairying (FAHD), Indian sub-continent is home to 9.06 million pigs contributing 1.69 % of the total livestock population of 536.76 million. Such pig population remains under a constant threat of FMD. Pigs are well known as ‘powerful aerosol emitters’ (Donaldson et al., 1987) or ‘amplifier hosts’ in FMD epidemiology as one infected pig produces up to 60-fold higher airborne virus per day than that from sheep and cattle (Alexandersen et al., 2003). FMD in pig has cataclysmic impact as illustrated during March 1997 in the Taiwanese pig industry (Donaldson, 1999). It is therefore irrefutable that control of FMD needs a multispecies approach including pig.

Accurate diagnosis of FMD is a critical component of effective control strategies, with the availability of a simple and robust assay being a fundamental pre-requisite for both diagnostic and serological evaluations in animal. Virus neutralization test (VNT) is time-consuming and tedious, while detection of structural antibodies in VNT or ELISA is of no use to diagnose infection-associated antibodies in places where vaccination is practiced on a regular basis. In order to obviate such constraints, different types of FMDV nonstructural protein (NSP)-based ELISAs including competitive, blocking and capture formats have been validated. Antibodies to 3ABC or 3AB polyprotein detected in ELISAs are considered to be the most reliable indicator of FMDV infection (Sorensen et al., 1998; Clavijo et al., 2004). In the current study, we optimized and validated an indirect ELISA (I-ELISA) with recombinant 3AB3 NSP fusion protein (Mohapatra et al., 2011) and evaluated its performance to assess antibodies against 3AB NSP of FMDV in porcine sera.