Mycobacterium bovis BCG Tokyo 172

Mycobacterium bovis is a major cause of tuberculosis in a range of animal species and man. It was also the progenitor of the M.bovis bacillus Calmette-Guerin (BCG) strain used as a vaccine against tuberculosis. BCG was derived by serial passages on slices of potato imbibed with glycerol for 13 years. Once the strain was proven to no longer be virulent it was disseminated and different laboratories continued this passaging. Different centers have different stocks of BCG, which have continued to change with time, accumulating insertion, deletion and single nucleotide polymorphisms.
This strain, Tokyo 172-1, is used for the production of BCG vaccine in Japan. It is an early derived strain subjected to low passage number, which has been suggested to make a better vaccine (PubMed:17372194). There are 18 regions of difference (more than 20 bp), 20 insertion or deletion mutations of less than 20 bp, and 68 SNPs between the two BCG substrains