Foot and mouth disease (FMD), an infection caused by the food and mouth disease virus (FMDV) is amongst the most contagious trans-boundary viral disease of cloven-hoofed ungulates. The disease has a broader geographical distribution with diverse host species including in domesticated livestock (cattle, pigs, goats and sheep), and susceptible wild artiodactyl with African Buffalo (Syncerus caffer) serving as the reservoir host or persistent carrier for SAT serotypes in Southern African regions.(Paton et al., 2018; Longjam et al., 2011; Wekesa et al., 2015). Outbreak of this infectious virus may results with devastation economic impacts due to the highly expenditures required for disease control, eradication and imposition of strict measures on movement on both domestic and international meat, meat products and livestock trading markets (Knight-Jones and Rushton, 2013).
Besides zooning, the use of vaccines is one of the most feasible and practical method to prevent, control and eradicate potential outbreaks of the FMD (Paton et al., 2009; Depa et al., 2012). The FMDV circulate within seven serotypes: O, A, C, Asia1, South African Territories (SAT1, 2 and 3) and specific serotype can be identified both genetically and serologically. The positive sensed single stranded RNA of the FMD has greater genetic variability, which resulted in the existence of diverse antigenic subtypes within different serotypes (Mittal et al., 2005; Paton et al., 2005). Because vaccination against one serotype of FMDV) does not confers immunity against others serotypes or subtypes of one serotypes (Feng et al., 2016; Paton et al., 2005). The immunogenicity of the current used inactivated whole virus vaccine of the FMDV depend on the wholeness of the most active component of the vaccine, the 146S particle which is the intact virion (Crowther et al., 1995). To date, the most recommended standard testing method to quantify 146S antigen particles is through sucrose density gradient centrifugation (SDG) (Barteling and Meloen, 1974). Even though the SDG can yield good antigen quantification, the test is mostly dependable on the operator, requires expensive instrumentation to run, it quantify only one sample every 5-7 minutes, it is very labour intensive and the detecting instrument cannot be automated. It cannot indicates whether the immunogenic epitopes on VP1 protein of 146S and intact and not degraded by proteases or trypsin effects. (Doel and Mowat, 1985; Van Maanen and Terpstra, 1990).
The use Double antibody sandwich-enzyme-linked immunosorbent assay (DAS-ELISA) in detecting the 146S antigen provide greater sensitivity and specificity. DAS-ELISA testing is highly rapid, robust, repeatable and timesaving. This tells allows the quantification of a larger number of sample in relatively fewer times. Most importantly DAS-ELISA is able to determine the integrity of the epitopes on VP1 essential for vaccine potency (Van Maanen and Terpstra, 1990; Feng et al., 2016)