Early diagnosis of Johne's disease in the American bison by monoclonal antibodies directed against antigen 85.

ABSTRACT

Several monoclonal antibodies derived from hybridomas from mice that had been immunized with recombinant Mycobacterium bovis antigen 85 (Ag85) were tested for reactivity against antigen 85 (Ag85) from M. bovis and against sera from 100 bison inoculated with M. paratuberculosis and from 100 control bison from a disease-free herd. Monoclonal antibodies mAb85.1, mAb85.44.1, mAb85.44.9, and mAb85.96 reacted against three or four 30-33-kDa bands of the Ag85 complex of M. bovis. Importantly, these mAbs also reacted with bands of similar molecular weight in the sera of bison inoculated with M. paratuberculosis. Additionally, when sera from 198 bison in four herds were reacted against mAb85.1 and mAb85.96, 26 bison reacted positively for the presence of Ag85 by either mAb or by both. These preliminary results indicate that monoclonal antibodies may eventually lead to a reliable diagnostic test for the early detection of M. paratuberculosis infections in ruminants as well as to a means for identifying contaminated dairy products.