Common enterobacterial antigen in Yersinia enterocolitica.

Production of the common enterobacterial antigen (CA) by strains of Yersinia enterocolitica (Y.e.) serotypes 3 and 9 (Winblad), by strains of 5 different Y.e. serogroups (Wauters) and various other bacteria was examined. Antibody against CA was raised by immunization of rabbits with E. coli O 14. Extract prepared from S. typhimurium was used for the sensitization of sheep erythrocytes with CA. Absorption and haemagglutination inhibition experiments showed that CA could be detected in heat extracts from all Y.e. strains examined, and in that from Yersinia pseudotuberculosis. CA was not detected in extracts from Pasteurella multocida, Francisella tularensis, Brucella abortus, Acinetobacter calcoaceticus or Pseudomonas aeruginosa. Anti-CA antibodies could not be demonstrated in serum from rabbits immunized with Y.e. bacteria, but were demonstrated in serum from rabbits immunized with a CA-containing fraction of the Y.e. extract. The possibility of participation of anti-CA antibody in indirect haemagglutination tests for detection of antibody to Y.e. O antigens is emphasized.