Enzyme-linked immunosorbent assay for Brucella ovis specific antibody in ram sera

An enzyme-linked immunosorbent assay (ELISA) for the detection of Brucella ovis specific antibody in ram serum was compared with the currently employed complement fixation test (CFT). Rabbit anti-sheep IgG coupled to horseradish peroxidase was used as the antibody-enzyme conjugate and 2,2'-azino-di[3-ethylbenzthiazolin sulphonate (6)] as the substrate. The ratio of the optical density at 414 nm for positive and negative control sera (P/N ratio) was used to optimise the parameters of the test. Ram serum samples (16,527) were tested using ELISA and CFT (warm and cold) over a one year period. The ELISA was more sensitive and provided a more reliable measure of B ovis specific antibody than did the CFT. Implications of employing ELISA as the sole test in an eradication scheme are discussed.