Sheep were immunized with killed Salmonella enterica serotype Urbana cells and their sera were tested in various serological tests for antibody to Brucella sp., Yersinia enterocolitica O:9 and Escherichia coli O:157
H:7. Of the eight sheep, all gave a positive agglutination reaction in the
brucellosis buffered
antigen plate agglutination test (BPAT), seven gave positive
brucellosis standard tube agglutination test (TAT) and
complement fixation test (CFT) results and four gave slightly positive reactions in a competitive
enzyme immunoassay (CELISA). Seven sera were negative in an indirect
enzyme immunoassay (IELISA-SLPS) using B. abortus smooth
lipopolysaccharide (SLPS)
antigen and all were negative in a fluorescence polarization assay (FPA-OPS) using B. abortus O-
polysaccharide antigen. Two sheep gave a slight positive reaction in an IELISA using Brucella rough
lipopolysaccharide antigen (IELISA-RLPS) and four sheep were slightly positive in an FPA using Brucella LPS core
antigen (FPA-CORE). All sheep had high antibody responses to S. enterica serotype Urbana, Y. and E. coli O:157 and 7 were positive for antibody to Y. enterocolitica O:9 when tested by IELISA. The sheep were negative when tested in the FPA using OPS from Y. enterocolitica O:9 but all were strongly positive in the FPA using OPS from E. coli O:157 while seven sheep had titers to S. enterica serotype Urbana. The impact on diagnostic serology for
brucellosis is discussed.