The antigens of Mycobacterium tuberculosis, H37Rv, studied by crossed immunoelectrophoresis. Comparison with a reference system for Mycobacterium bovis, BCG.

On the basis of a previously developed reference system for Mycobacterium bovis, BCG, in crossed immunoelectrophoresis (CIE), antigens of Mycobacterium tuberculosis were identified in an analogous system. A majority of the numbered lines in the BCG system were also present and identified in the M. tuberculosis system. The corresponding antigens in the two systems were identified by dual dilution in CIE, and using monospecific antisera and monoclonal antibodies. Some of the antigens were specifically identified by the demonstration of enzyme activity and by means of hydroxyapatite, concanavalin A (Con A), EDTA, and blue-Sepharose. Three antigens (nos 10, 78, and 81), which were found in high concentrations in M. tuberculosis culture fluid, were not identified or were present in low concentrations in BCG culture fluid. The high percentage of corresponding antigens confirms that there is a very close taxonomic relationship between BCG and M. tuberculosis. Corresponding antigens in BCG and M. tuberculosis did not differ in electrophoretic mobility in the antigenic preparations studied.