Quantification of intact 146S foot-and-mouth disease antigen for vaccine production by a double antibody sandwich ELISA using monoclonal antibodies

Abstract

A double antibody sandwich (DAS) enzyme-linked immunosorbent assay (ELISA) was developed to quantify 146S antigen of foot-and-mouth disease virus (FMDV) strain A10 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 VP1. 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.