Vaccination with pure Mycobacterium leprae proteins inhibits M. leprae multiplication in mouse footpads.

In this study, we evaluated vaccination with a number of purified, as well as recombinant, Mycobacterium leprae proteins for protective efficacy in mice. BALB/c mice were immunized intradermally with various native somatic (purified) or recombinant M. leprae proteins and their synthetic polypeptides emulsified in Freund's incomplete adjuvant. The protective efficacy of these preparations was assessed by enumeration of bacilli in the footpads of mice challenged with viable M. leprae 1 to 2 months following immunization. Protection was afforded by the purified and recombinant 10-kDa M. leprae cytoplasmic heat shock protein, the recombinant cell wall-associated 65-kDa M. leprae heat shock protein, and to a lesser extent, the purified 28-kDa M. leprae cytoplasmic protein (superoxide dismutase). Vaccination with either the purified or recombinant 35-kDa M. leprae cell membrane protein, the synthetic 27-amino-acid N-terminal peptide of the 10-kDa protein, the recombinant 18-kDa M. leprae protein, or the purified 22-kDa cell membrane protein was ineffective. When the interval between immunization and challenge was increased to 6 months, the purified 10-kDa M. leprae protein and the recombinant 65-kDa M. leprae protein lost vaccine efficacy, while a sodium dodecyl sulfate-soluble protein fraction of the M. leprae cell wall (soluble proteins), as had been found previously, continued to protect, suggesting that multiple M. leprae protein epitopes are critical for solid vaccine protection.