Differentiation of Brucella abortus and Yersinia enterocolitica serotype 09 infections: use of lymphocyte transformation test.

Cell-mediated immune responses in cattle infected with Brucella abortus Strain 544, cattle infected with Yersinia enterocolitica serotype 09 and non exposed cattle were studied by an in vitro whole-blood lymphocyte stimulation procedure. A soluble Brucella polypeptide containing some lipopolysaccharide prepared from Brucella abortus strain 99 was used as antigen while Concanavalin A was used as mitogen. Results were assayed for (6-3H) thymidine incorporation into deoxyribonucleic acid. All the cattle from which Brucella abortus was recovered developed very high lymphocyte transformation responses while cattle infected with Yersinia enterocolitica 09 and non exposed cattle did not develop high lymphocyte stimulation reactions. The animals infected with Yersinia enterocolitica 09 were strongly positive to the Rose Bengal, serum agglutination, Complement fixation and Coombs' antibovine globulin tests. One lactating cow infected with Yersinia enterocolitica 09 was positive to the Brucella milk ring test. It was concluded that the lymphocyte stimulation assay could be used to differentiate bovine brucellosis from yersiniosis.