In contrast, existing drugs are generally effective only after the bacteria activates. A second significant breakthrough was announced by a research consortium in August. The team, which included Rockefeller's McKinney, discovered an enzyme that is critical to the survival of the bacteria in the granulomas. When the gene for that enzyme is knocked out, the bug can no longer resist the body's immune response. The team is now working with Glaxo-Wellcome to develop drugs that would target this enzyme.
Any commercial drug is still at least seven years away from approval, researchers caution.
Even further out is a possible vaccine. Because the TB bacterium can hide from the immune system, a typical antibody-based vaccine would not work in most people. The NIH is conducting a major effort to develop a TB vaccine, and expects a few candidates to enter early human trials next year. One of these was developed by Corixa Corp. in Seattle. The company identified a group of U.S. doctors who were exposed to TB while working in South America but were able to purge the infection.