Comparison of the enzyme-linked immunosorbent assay with other tests for brucellosis, using sera from experimentally infected heifers.

During an evaluation of H-38 Brucella melitensin vaccine, serum samples were collected from 24 Hereford-Angus heifers (nonvaccinated controls) before exposure and then 11 times between 12 and 102 days after exposure to Brucella abortus strain 2308. Antibody concentrations were determined by the enzyme-linked immunosorbent assay (ELISA) and by standard tube agglutination (STA), 2-mercaptoethanol agglutination (ME), microtitration complement-fixation (MCF), and automated complement-fixation (ACF) tests. The results were compared in terms of concordance, sensitivity, and specificity. Concordance between the ELISA and other tests were 100% (STA), 75.7% (ME), 97.8% (MCF), and 95.2% (ACF). On the 12th day after heifers were exposed, antibodies were detected in 18.2% of the infected heifers by the ELISA and in 11.1% with the STA test, in 0% with the ME test, in 33.3% with the MCF test, and in 44.4% with the ACF test. On the 25th day, ELISA and all serotests (except ME) detected antibodies in all infected heifers. All serum samples from the heifers before exposure were negative.