Characterization of murine monoclonal antibodies specific for the 45/47 kDa antigen complex (APA) of Mycobacterium tuberculosis, M. bovis and BCG.

ABSTRACT

The alanine-proline antigen (APA), representing less than 2% of the released or excreted material during Mycobacterium tuberculosis or bacillus Calmette-Guérin (BCG) growth, is a dominant antigen present during M. tuberculosis infection or BCG immunization. To obtain new tools to dissect the major epitopes of the APA molecules, seven monoclonal antibodies (mAbs) against the purified molecules were developed. Epitope maps of the mAbs were obtained on APA molecules absorbed on plastic surfaces or in solution (BIAcore technology). The mAbs were found to be independent or to be different despite binding to adjacent or overlapping epitopes. In Western blot assays some proteins secreted in culture fluid by M. avium, M. kansasii, M. smegmatis or M. xenopi were also labelled by six of the seven antibodies. Conversely one antibody was specific for the proteins from the M. tuberculosis complex (I10-0,3) demonstrating that the APA molecules have some properties or general conformations that are specific for M. tuberculosis and M. bovis.