Monoclonal antibodies and characterization of epitopes of smooth Brucella lipopolysaccharides

Four mouse monoclonal antibodies generated against Brucella melitensis 16M, and three generated against B. suis 1330 were analysed. An ELISA (enzyme-linked-immunosorbent assay) with whole cells as antigens was used to determine cross-reactivities with other Gram-negative bacteria. Two antibodies showed cross-reactivity with smooth Brucella strains only. Five antibodies also reacted with Yersinia enterocolitica O:9, but not with other bacteria. Two of these antibodies had significantly higher titres with A greater than M serotype Brucella strains, indicating that these epitopes are related to the antigenic A complex. The antigenic determinants recognized by the monoclonal antibodies showed varying degrees of susceptibility towards oxidation. They were shown by immunoblotting to be located on the polysaccharide moiety of the O-side chain.