BCG-induced protection: effects on innate immune memory

Semin Immunol. 2014 Dec;26(6):512-7. doi: 10.1016/j.smim.2014.09.006. Epub 2014 Oct 23.


The Bacille Calmette-Guerin (BCG) vaccine is the only vaccine proved to be effective against tuberculosis and it remains the most commonly used vaccine worldwide. In addition to its effects on mycobacterial diseases, an increasing body of epidemiological evidence accumulated since its introduction in 1921 shows that BCG also exerts beneficial non-specific effects ranging from protection against non-mycobacterial diseases, decreased incidence of allergic diseases, and treatment of certain malignancies. The biological substrate of these effects is mediated partly by heterologous effects on adaptive immunity, but also on the potentiation of innate immune responses through epigenetic mechanisms, a process termed 'trained immunity'. The process of trained immunity may also play a role in the beneficial effects of BCG against tuberculosis and Mycobacterium tuberculosis infection, and this could have important consequences for our quest for improving vaccination strategies.

Keywords: BCG; Innate immune memory; Trained immunity; Tuberculosis.

Publication types

  • Historical Article
  • Research Support, Non-U.S. Gov't
  • Review

MeSH terms

  • Adaptive Immunity
  • BCG Vaccine / administration & dosage
  • BCG Vaccine / chemistry
  • BCG Vaccine / history
  • BCG Vaccine / immunology*
  • Clinical Trials as Topic
  • Epigenesis, Genetic / immunology
  • History, 20th Century
  • History, 21st Century
  • Humans
  • Immunity, Innate / drug effects*
  • Immunologic Memory*
  • Mycobacterium bovis / chemistry
  • Mycobacterium bovis / immunology
  • Mycobacterium tuberculosis / immunology*
  • Tuberculosis, Pulmonary / immunology
  • Tuberculosis, Pulmonary / microbiology
  • Tuberculosis, Pulmonary / prevention & control*
  • Vaccination*


  • BCG Vaccine