BCG has always been an appealing candidate for leprosy control due to its demon-
strated efficacy and attractive native porperties such as a high degree of safety in all age groups, persistence in the intracellular environment and good adjuvant properties. Many investigators believe these attributes be improved upon and have successfully expressed foreign genes derived from other human pathogens in BCG. Auxotrophic mutants provide an approach for producing a "crippled" BCG that retains immunogenicity and may prove safer for implementation in immunocompromised individuals.
The question remains then, can BCG be redesigned to better express M. leprae-rele-vant protein antigens resulting in an improved BCG vaccine for leprosy? It is very likely that this area of investigation will be pursued vigorously and should this approach or another yield a potent vaccine for leprosy, an even larger question will be facing us, that is; who will pay for testing the vaccine in humans? Alternative funding sources may be the answer. It seems prudent that groups involved in vaccine research should keep their goals in line with current trends in TB vaccine development. Newly developed TB vaccines should be designed with combined protective efficacy to include leprosy. This will better insure the potential of testing a new vaccine with the sponsorship of tuberculosis funding agencies.
T. Gillis, GW Long Hansen's Disease Center, LA, U.S.A
