Topological and functional analysis of epitopes on the S(E2) and HE(E3) glycoproteins of bovine enteric coronavirus.

Monoclonal antibodies (Mabs) were selected which reacted with bovine enteric coronavirus S and HE. Mabs to S were used to identify 2 cleavage products of S, S/gp105 and S/gp90. Monoclonals to S/gp105 and HE neutralised the virus; only Mabs to the latter inhibited haemagglutination and acetyl-esterase activity. Topological distribution of epitopes was studied on these 3 glycoproteins by means of competition binding experiments. Two independent epitopes were characterised on HE, 4 on S/gp105, and 2 on S/gp90. Neutralising Mabs defined one major site on both S/gp105 and HE; however a minor neutralisation epitope was also delineated on S/gp105. Functional mapping using neutralisation-resistant mutants confirmed the topological distribution of epitopes on S/gp105.