BCG Vaccine

Introduction

Fig. 1. Image of a dendritic cell after ingesting a small amount of the BCG vaccine. Image: Institute for Animal Health http://www.bbsrc.ac.uk/news/health/2012/120126-pr-how-to-make-better-vaccines.aspx

Bacille Calmette Guerin (BCG) is the most common vaccine administered to combat tuberculosis disease in the world. (1) The vaccine contains a weakened live strain of Mycobacterium bovis, which is present in cows and shares a common ancestor with the human tubercule bacillus Mycobacterium tuberculosis (2). Similar to other vaccines, BCG creates the formation of antibodies from the harmless strain of Myobacterium bovis to help prevent tuberculosis, and the vaccine usually leaves a skin lesion or a scar (1). The efficacy of BCG vaccine varies from 0-80% depending on age, the type of BCG vaccine, and the population (1). Although BCG remains as the primary vaccine against tuberculosis, it has only produced variable amounts of success. Many factors, including recent findings that distinct BCG strains have very different biochemical characteristics due to mutations, have further complicated the issue (1). Researchers are currently searching for a more effective way to treat tuberculosis disease, but none has been found to date (1).

Origin

The origin of the Bacile Calmette Guerin virus began when Albert Calmette and Camille Guerin started working on Mycobacterium bovis in 1908. After the stain was attenuated 230 times over thirteen years, BCG was used as a vaccine to treat tuberculosis (1). The strain went through many unknown genetic changes as it became less virulent in animals. After the original success of the vaccine, it was distributed all around the world. However, as the vaccine underwent distribution, the newly distributed strains underwent distinct genetic changes (1). BCG strains continued to change as individual countries altered the strain to fit their own needs (3). Currently, there are seven strands that are administered throughout the world, but they differ in gene sequences and protein production (3).

References

1. 2. 3. 4. 5. 6. 7.

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Image of a dendritic cell after ingesting a small amount of the BCG vaccine. Image: Institute for Animal Health http://www.bbsrc.ac.uk/news/health/2012/120126-pr-how-to-make-better-vaccines.aspx

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Edited by Scott Treiman, student of Joan Slonczewski for BIOL 116 Information in Living Systems, 2013, Kenyon College.