ABSTRACT
Identification of M. leprae antigens recognized by T-cell is important for specific diagnosis, vaccine development and understanding the basic mechanisms involved in protection against and pathogenesis of leprosy. Screening of an M. leprae recombinant DNA library with antibody probes led to the identification of half a dozen M. leprae antigens recognized by B-cells. When tested for T-cell reactivity, all the antigens recognized by antibodies were shown to have T-cell reactivity. However, among these antigens 18 kDa, 65 kDa and 70 kDa heat shock proteins (hsps) were most frequently recognized by T-cell lines and clones established from healthy donors vaccinated with killed M. leprae. A 24 kDa secreted antigen of M. leprae with T-cell epitope specific for M. leprae and M. tuberculosis complex was identified by direct screening of the recombinant DNA library with T-cell clones. The recombinant T-cell antigens of M. leprae were recognized by memory T-cells of Th1 type in association with multiple HLA-DR molecules. Epitope mapping with synthetic peptides identified M. leprae-specific as well as cross-reactive T-cell epitopes on the 18 kDa, 65 kDa and 70 kDa hsp antigens. In conclusion, our studies suggest that the recombinant antigens of M. leprae could be useful as reagents for specific diagnosis as well as in subunit and recombinant vaccine design against leprosy.