Serological confirmation of Brucella abortus and Yersinia enterocolitica O:9 O-antigens by monoclonal antibodies.

Murine monoclonal antibodies that bind the O-antigens of Yersinia enterocolitica serotype O:9 and Brucella abortus 1119-3 were generated after immunization of BALB/c mice with killed, whole cells. Highly purified lipopolysaccharide preparations from each organism were used to screen for antigen-specific antibodies. Immunization with B. abortus cells induced 56 antigen-specific hybrids, and 10 of the highest antibody-producing clones were selected for further study. Seven of these clones secreted immunoglobulin G, and three secreted immunoglobulin M antibodies. Immunization with Y. enterocolitica cells resulted after fusion in 76 antigen-specific hybrid cell lines; from these, seven immunoglobulin G-secreting clones were selected for study. The serological cross-reactivity of the B. abortus and Y. enterocolitica O-antigens was established by enzyme-linked immunosorbent assay, immunoprecipitation, and agglutination tests with the monoclonal antibodies induced by each bacterium. This serological cross-reactivity is consistent with the structural identity of the two O-antigens established by chemical analysis.