VMRD’s test for foot-and-mouth disease virus (FMDV) is a competitive enzyme-linked immunosorbent assay (cELISA) that detects antibodies against the FMDV non-structural polyprotein 3ABC through inhibition of specific monoclonal antibody binding to a highly immunogenic yet highly conserved epitope within the target protein. The plastic wells of the assay plate are coated with recombinant 3ABC antigen, and the presence of horseradish peroxidase (HRP)-labeled 3B-specific monoclonal antibody is detected by the addition of enzyme substrate and quantified by subsequent color product development. Strong color development indicates little or no inhibition of monoclonal antibody binding and therefore the absence of anti-FMDV antibody in sample sera. 

Weak color development occurs when binding of the monoclonal antibody to the antigen on the plate is blocked by FMDV-specific antibodies present in the sample sera. This test distinguishes between infected and vaccinated animals as a DIVA assay because 3ABC is only induced in the presence of replicating virus and is not included in purified vaccines. Additionally, this assay has been shown to detect antibodies to all 7 FMDV serotypes (A, O, C, Asia 1, SAT 1, SAT 2, and SAT 3). The cELISA format enhances specificity while offering the flexibility of multispecies use, and is currently USDA-licensed for bovine, porcine, and ovine sera. 

When outside investigators compared this kit to previously available commercialized tests for FMDV, the VMRD cELISA performed better in almost every aspect, including enhanced sensitivity and specificity for both bovine and porcine samples. A particular advantage of this kit is the rapid run time of 140 minutes, which is greatly improved from other products that require overnight processing. It is also a select agent-free assay, which allows the assay to be manufactured and used in FMD-free regions without high-level biosecurity precautions.