IDENTIFICATION AND CHARACTERIZATION OF IMMUNODOMINANT ANTIGENS DURINGTHE COURSE OF INFECTION WITH BRUCELLA-OVIS

The seroresponse against Brucella ovis of 8 intrapreputially and 6 int ravenously infected rams and 9 ewes infected through mating was analyz ed by electrophoretic immunoblotting. Additionally, 87 sera from chron ically infected rams that were shedding B. ovis in their semen, 226 se ra from rams belonging to infected flocks, and 324 sera from false-pos itive complement fixation test (CFT) reactors were examined. In all in fected animals, antibody reactivity was predominantly found against 5 B. ovis components of 8-12, 17, 19, 29, and 63 kD, of which the 29-kD antigen was most dominant in the seroresponse. Antibodies to the 29-kD component were present in 93-100% of the infected sheep in each infec ted group, whereas the frequency of antibodies to the 4 other componen ts varied considerably among and within the different groups. No react ivity against the 29-kD antigen was found in the false-positive CFT re actors. By using monoclonal antibodies against known bacterial macromo lecules, the immunodominant antigens were identified as rough lipopoly saccharide (8-12 kD), outer membrane proteins (17, 19, 29 kD), and a h eat-shock protein (63 kD).