1. Introduction The FMD-Ab ELISA is developed to detect the O type antibodies of Porcine Foot and Mouth Disease in porcine serum samples and assess the immunity conditions against FMD in the pig farms. 2. Principle The kit is based on an indirect enzymatic immunoassay.The antigen is coated on plates. When a sample serum contains specific antibodies against virus, they will bind to the antigen on plates. Wash the unbound antibodies and other components. Then add a specific peroxidase conjugate(IgG-HRP). After incubation and washing, add the TMB substrate. A colorimetric reaction will appear, measured by a spectrophotometer.