Identification of immunoreactive membrane antigens of Brucella ovis by ELISA profiling

Enzyme-linked immunosorbent assay (ELISA) profiling was used to identify the immunoreactive membrane antigens of Brucella ovis. Immunoreactive membrane antigens obtained after detergent extraction of the bacterial membrane complex (inner and outer membranes) were resolved into five peaks (A, B, B1, C and D) by gel permeation chromatography. Aliquots from each of the chromatographed fractions were coupled to 96-well microtitre plates and immunoreactive fractions identified with sera from two rams. Serum from ram 1 which had been vaccinated with a single injection of formalin-killed B ovis emulsified in incomplete Freund's adjuvant identified A and B as the major immunoreactive peaks. Serum from ram 2, which had been successfully infected with B ovis, reacted mainly against peaks A, B1, C and D. This observation facilitated the use of A, B, B1, C and D peak antigens as test reagents to examine the serological response of 12 other rams exposed to B ovis by vaccination or intraconjunctival or intravenous inoculation. Sera from rams which developed productive infections reacted strongly against peaks A, B1, C and D while vaccinated rams had preferential antibody activity against peaks A and B.