An enzyme-linked immunosorbent assay (ELISA) was used to detect antibodies to Brnce/la abortus in bovine serum. The assay was standardized in terms of antigen coating condition, optimal antigen concen-tration, serum and conjugate dilutions. The most optimal conditions for antigen coating was that Ll'S antigen was diluted to lug/ml with carbonate buffer (pH 9.6) followed by coating at 4°C overnight with 0.1 ml of diluted an.tigen. The gelatin NET solution was most effective in blocking. The negative cutoff point was s.et at 0.40 while serum sample was diluted to 1: 100.
The relative sensitivity and specificity of ELISA to both results of complement fixation test and tube agglutination test were 100% in 22 diagnostic positive sera. The c-0rrelation coefficients of ELISA to these two tests were 0.927 and 0.943.