Prospects for new vaccines against tuberculosis.

The spectacular failure of the existing bacille Calmette-Guérin (BCG) vaccine in recent tuberculosis-control trials has prompted a search for potential replacements. Imaginative approaches currently under development include the modulation of BCG by the production of auxotrophic mutants or cytokine-secreting recombinants, and the development of subunit vaccines based on the major proteins of Mycobacterium tuberculosis.