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.