Comparison of thermostable macromolecular antigens from leprosy-associated bacteria

Three types of bacteria are associated with leprosy: Mycobacterium leprae, leprosy-derived corynebacteria (LDC), and armadillo-derived mycobacteria (ADM). The immunological relationships between these three types of bacteria and Mycobacterium bovis BCG, used as a reference, were determined by cross-immunoelectrophoresis. When compared with the reference, cross-reactions were observed with a variable number of antigens: 2 in the case of strain LDC 15, 4 with M. leprae, and from 1 to 10 in the case of the ADM, depending on their subgroup. Next, thermostable macromolecular antigens (TMAs), the major cross-reactive antigens of leprosy-associated bacteria, were compared by anti-TMA antibody ELISA tests. The LDC TMAs displayed high cross-reactivity between the subgroups and lower cross-reactivity with the TMAs of M. bovis BCG. Evidence for the presence of a species-specific moiety in TMA of the different LDC was obtained by using depleted anti-TMA antisera. Western blot analysis revealed the presence of many proteins in the TMAs of LDC and M. bovis BCG, some of them being species-specific and other cross-reactive.