A vaccine containing bacillus Calmette-Guerin (BCG), an attenuated strain of Mycobacterium bovis, with non-specific immunoadjuvant and immunotherapeutic activities. Although the mechanism of its anti-tumor activity is unclear, immunization with BCG vaccine likely activates a Th1 cytokine response that includes the induction of interferon. Vaccination with BCG vaccine may be immunoprotective against infection with Mycobacterium tuberculosis. or A weakened form of the bacterium Mycobacterium bovis (bacillus Calmette-Guérin) that does not cause disease. BCG is used in a solution to stimulate the immune system in the treatment of bladder cancer and as a vaccine to prevent tuberculosis. Also called bacillus Calmette-Guérin.