Abstract
Mycobacterium bovis BCG vaccine strains were compared with Mycobacterium tuberculosis by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. A 25-kDa protein observed in the BCG strains was absent in M. tuberculosis. Rabbit antibodies specific to the 25-kDa protein uniquely identified this protein in BCG strains but not in M. tuberculosis. It is suggested that the 25-kDa protein and polyclonal antibodies directed against this antigen can be exploited to distinguish BCG strains from M. tuberculosis.