Bacillus Calmette-Guérin (live attenuated Mycobacterium bovis) (BCG)

Bacillus Calmette-Guérin (BCG) is a live attenuated strain of Mycobacterium bovis, originally developed by repeated subculture to reduce virulence[7]. It is the only vaccine approved worldwide for the prevention of tuberculosis, particularly severe forms such as infant meningitis and miliary TB[3][5]. BCG is also used as a first-line immunotherapeutic agent for non-muscle invasive bladder cancer, where it is instilled intravesically to activate local immune responses and reduce tumor recurrence[3][5]. BCG's protective efficacy in tuberculosis varies among substrains - resulting from historical genetic differences - and it can trigger robust innate and adaptive immune responses[1][4]. Intradermal or mucosal administration leads to local infection and immunological activation, mainly through recognition by antigen-presenting cells and stimulation of T-cell mediated immunity[4]. BCG is also exploited as a recombinant bacterial vector for novel vaccine development targeting other infectious or neoplastic diseases[3][2]. The main safety challenges include potential for disseminated infection in immunosuppressed individuals and variable efficacy depending on substrain and dosing[1][5]. The correct canonical target is the vaccine organism itself (Bacillus Calmette-Guérin), not a molecular target such as an enzyme, receptor, or transporter. If structured data is desired for drug targets at the molecular level, BCG should not be classified alongside genes/proteins but as a live attenuated vaccine organism.

Other names

Bacillus Calmette-GuérinBCGAttenuated Mycobacterium bovisMycobacterium bovis BCG

Induces strong cell-mediated immunity, predominantly T helper 1 (Th1) type response. Activation of innate immunity (macrophages, dendritic cells, monocytes via pattern recognition receptors like TLR2, TLR4, TLR9). Promotes production of cytokines (IL-2, IFN-γ, TNF-α, IL-12). Direct local immune activation and stimulation of antitumor responses in the bladder wall.