Specific enzyme-linked immunosorbent assay for detection of bovine antibody to Brucella abortus.

Six soluble antigens prepared from Brucella abortus were compared with a salt-extractable protein (CSP) antigen in an enzyme-linked immunosorbent assay for the detection of antibody to B. abortus in cattle sera. Of seven preparations tested, antigens from B. abortus soluble antigen (prepared from an autoclaved cell suspension) and CSP were stable on frozen storage. Enzyme-linked immunosorbent assay with CSP antigen under optimal conditions was from 100- to 700-fold more sensitive than the standard agglutination, card, Rivanol precipitation-plate agglutination, and the complement fixation tests in detecting immunoglobulin G antibody. From a practical point of view, however, using the most stringent criteria for determining an "upper negative" value, the enzyme-linked immunosorbent assay with CSP was at least 12-fold more sensitive than the standard agglutination test and any of the other serological tests. Furthermore, the enzyme-linked immunosorbent assay with CSP was specific for antibody to B. abortus.