Development and evaluation of diagnostic tests for the serological diagnosis of brucellosis in swine

A competitive enzyme-linked immunosorbent assay (c-ELISA), an indirect ELISA (i-ELISA) and a dissociation-enhanced lanthanide fluorescence immunoassay (DELFIA) were developed to test for antibodies to Brucella suis in pig and wild boar sera. An anti-Brucella-LPS monoclonal antibody (MAb 4B5A) (c-ELISA and DELFIA) and an anti-swine IgG monoclonal antibody (MAb 10C2G5) (i-ELISA) were used for the three assays. The specificity (Sp) and sensitivity (Se) of the assays gave the following results: Se and Sp=100% at a cut-off value of 61.0% (B/B0%) for c-ELISA; Sp=99.1% and Se=100% at a cut-off value of 21.7% (percentage positivity: PP%) for i-ELISA; Sp=91.0% and Se=75% at a cut-off value of 37.0% (B/B0%) for DELFIA. In addition, the performance of a commercial fluorescence polarisation assay (FPA), standardised for bovine sera, was evaluated in swine sera. The specificity and sensitivity obtained were both 100% at a cut-off value of 99.5 (millipolarisation unit values). These results suggest that the combination of c-ELISA, i-ELISA and FPA can be used to improve the serological diagnosis of swine brucellosis.