Comparison of TRACK XI fluorometric immunoassay system with other serologic tests for detection of serum antibody to Brucella abortus in cattle.

The TRACK XI system (TRACK) is a commercially available fluorometric immunoassay system that has been adapted for the detection of antibodies to several antigens in various animal species. Serum antibodies to Brucella abortus were detected by TRACK and compared with those obtained from two primary binding assays (a fluorometric immunoassay [FIAX] and an enzyme-linked immunosorbent assay) and three standard serological tests (complement fixation, Rivanol precipitation, and CARD tests). A total of 298 serum samples were tested by each serological test. Of these serum samples, 134 were negative controls, 43 were from cattle 1 month after vaccination with B. abortus 19, and 121 were from cattle 10 to 12 weeks after a midgestational, intraconjunctival challenge with B. abortus 2308. The results of this study indicated that TRACK is both reproducible and accurate. The results compared favorably with those of other serological methods. TRACK is more rapid than either the enzyme-linked immunosorbent assay or FIAX system. TRACK was the most sensitive (96.3%) test, with a specificity of 100%.