Serological cross-reactions between Brucella abortus and Yersinia enterocolitica 0:9.

Yersinia enterocolitica (Ye) 0:9 is an organism of great significance in veterinary medicine largely as a result of its cross-reaction with Brucella abortus (Ba). Boty Ye 0:9 and Ba possess somatic antigens in common; as a result of which animals exposed to Ye 0:9 have an immune response which is distinguishable only with difficulty from that induced by Ba. Cattle were exposed to Ye 0:9 by the oral or intramammary routes. Oral exposure failed to generate significant serologic response. In contrast, intramammary inoculation produced a marked response. Serum antibodies provoked in this manner reacted strongly with Ba. The anti-Brucella response provoked by inoculation of Yersinia was sufficient to render milk and serum Brucella-seropositive as measured by the standard milk ring and serum agglutination tests. While both Ba and Ye 0:9 have 9 antigens in common, they differ significantly with respect to motility. Thus Ba is always non motile while Ye is motile when grown at room temperature. The presence of Yersinia H agglutinins in serum were shown to be evidence of previous exposure to Ye. The H agglutinins were not generated by Brucella infection. A rapid H agglutination test was shown to provide this differentiation without interference from cross-reacting O antigens. Results of Ba O and Ye O and OH antigens used in the agglutination test were found useful to differentiate antibodies against Ba from those induced by Ye 0:9 in cattle sera. The existence of enterobacterial common antigen (ECA) in Ye and its absence in Ba were utilized in an attempt to provide a method to distinguish Brucella infections from those with cross-reacting Yersinia.(ABSTRACT TRUNCATED AT 250 WORDS)