Monoclonal Antibodies to Bovine Coronavirus Glycoproteins E2 and E3: Demonstration of in vivo Virus-neutralizing Activity

Six monoclonal antibodies (MAbs) to bovine coronavirus (BCV, Quebec isolate) E2 and E3 glycoproteins which were found previously to be neutralizing in vitro were examined for virus-neutralizing activity in vivo. Surgically ligated intestinal loops of newborn colostrum-deprived calves were virus-inoculated, mock-infected or inoculated with a mixture of virus and antibody. Of the six BCV-specific MAbs, four were found to be protective against a virulent field isolate of BCV, as indicated by a reduction in villous atrophy. These MAbs were specific to antigenic domain A and antigenic domains A1 and A2 on the E2 and E3 glycoproteins respectively. MAbs to antigenic domains B and C on the E2 and E3 glycoproteins, respectively, were not protective.