COMPARISON OF POLYCLONAL, MONOCLONAL AND PROTEIN-G PEROXIDASE CONJUGATES IN AN ENZYME-LINKED-IMMUNOSORBENT-ASSAY FOR THE DIAGNOSIS OF BRUCELLA-OVIS IN SHEEP

The sensitivities of three commercial peroxidase conjugates (polyclona l anti-sheep IgG, recombinant protein G and a monoclonal anti-ruminant IgG(1)) in an enzyme-linked immunosorbent assay for Brucella ovis wer e evaluated. The monoclonal and protein G conjugates reduced, but did not totally remove, the characteristic background reactivity observed with the sera from brucella-free sheep. The protein G conjugate provid ed the best sensitivity, similar to that obtained with the classical g el diffusion test. Both tests were highly specific when testing sera f rom brucella-free animals but detected as positive a large proportion of sera from both Brucella melitensis-infected and B melitensis Rev I- vaccinated sheep.