Production and epitopic characterization of monoclonal antibodies against bovine beta-lactoglobulin

Sixty-nine murine monoclonal antibodies were produced against the bovine beta-lactoglobulin (beta-LG) variant B. Thirty-eight specificity groups of monoclonal antibodies were defined according to the reactivity in indirect or capture ELISA with bovine beta-LG B, for bovine beta-LG B coated at pH ranging from 2.3 to 9.4, and for beta-LG with naturally occurring residue substitutions such as bovine beta-LG variant A and ovine, caprine, porcine, and equine beta-LG. Ten monoclonal antibodies appeared to be monospecific for bovine beta-LG, 58 monoclonal antibodies recognized only ruminants beta-LG, and 1 recognized all species. The specificity of the monoclonal antibodies was also studied with sequenced tryptic peptides of beta-LG variant B. Critical residues involved in the epitopes of nine classes of monoclonal antibodies were characterized. Moreover, 5 monoclonal antibodies were able to discriminate between a fresh solution of beta-LG and a solution that had been stored for greater than or equal to 2 d at 4 degrees C, and 3 monoclonal antibodies distinguished bovine beta-LG that has been purified by gel filtration from that purified by salt fractionation. This array of monoclonal antibodies could be efficient probes for characterizing conformational structures involved in biological properties of beta-LG (e.g., interaction with ligands and hypersensitivity reactions) and for studying conformational changes occurring upon physical treatments such as heat denaturation.