Serological cross-reactions between different Brucella species and Yersinia enterocolitica. Immunodiffusion and immunoelectrophoresis.

By immunodiffusion and immunoelectrophoresis tests in agarose serological cross-reactions were demonstrated between Yersinia enterocolitica type IX and Brucella strains from four species (Brucella abortus, Brucella melitensis, Brucella suis and Brucella neotomae). No qualitative differences between these strains in their tendencies to cross-react with Yersinia enterocolitica type IX were observed. Brucella canis and Brucella ovis, which have nonsmooth colonial morphology, gave no demonstrable cross-reaction with Yersinia enterocolitica type IX. The results of absorption tests and qualitative staining reaction of the obtained precipitation lines suggest that the antigenic determinants common to Brucella and Yersinia enterocolitica type IX seemed to be associated with the outer layer and in the lipopolysaccharide complex of the respective bacteria. By immunodiffusion and immunoelectrophoresis it was possible to identify in hyperimmune sera those antibodies that derive from Brucella and Yersinia enterocolitica type IX.