Quantification of Intact 146s Foot-and-mouth Antigen for Vaccine Production by a Double Antibody Sandwich ELBA using Monoclonal Antibodies

A double antibody sandwich (DAS) enzyme-linked immunosorbent assay (ELISA) was developed to quantify 146s antigen of foot-and-mouth disease virus (FMDV) strain Al 0 Holland grown in suspension cultures of surviving bovine tongue epithelium. When virus harvests were incubated with trypsin-which affects VP1 , the most immunogenic structural protein of FMDV-the concentration of 146s antigen as determined by ELISA was reduced by >90%. Therefore, the test detected essentially only those virus particles with intact VPl. When the test was compared with the sucrose density gradient method, concentrations of 146s antigen correlated well (r = 0.87). The rate of variation in both tests was the same. In contrast to the sucrose density gradient method, the DAS-ELISA can simultaneously quantify 146s antigen in many samples, and also indicates when VP1 of 146s particles has disintegrated by the action of proteases.