Enzyme Immunoassay Using Mouse Monoclonal Anti‐bovine Antibodies for the Detection of<i>Brucella abortus</i>Antibodies in Cow Milk

Abstract

Individual milk samples and artificially constructed tank milk samples from cows with naturally occurring brucellosis were examined by the enzyme-linked immunosorbent assay (ELISA) using sonicated B. abortus S-99 antigen, and mouse monoclonal anti-bovine IgM, IgA, and IgG1 conjugates. ELISA results were compared with the results of the milk ring test using either 1 ml milk (MRT-1) or 8 ml milk (MRT-8). The ELISA using mouse monoclonal anti-bovine IgG1 conjugate was sensitive and specific. In testing individual milk samples and constructed tank milk samples containing milk with low titers in the MRT-1 the ELISA was superior to the MRT-1, and MRT-8. In testing other milk samples, the ELISA was as sensitive or slightly less sensitive than the MRT-8. From a total of 5,910 milk samples collected from cows free from brucellosis, only 24 (0.4%) samples tested positive in the ELISA. All 500 tank milk samples collected from farms negative for brucellosis tested negative in the ELISA. We concluded that the ELISA is a good substitute for the MRT-1 to detect antibodies against Brucella in milk from individual cows. When tank milk is tested for antibodies against Brucella, however, both the MRT-8 and the ELISA should be used.