Complete Genome Sequence, Genome Stability and Phylogeny of the Vaccine Strain Mycobacterium bovis BCG SL222 Sofia.

Mycobacterium bovis bacillus Calmette-Guérin (BCG) is the only live attenuated vaccine available against tuberculosis. The first BCG vaccination was done exactly 100 years ago, in 1921. The BCG vaccine strains used worldwide represent a family of daughter sub-strains with distinct genotypic characteristics. BCG SL222 Sofia is a seed lot sub-strain descending from the Russian BCG-I (seed lot 374a) strain and has been used for vaccine production in Bulgaria since 1972. Here, we report the assembled circular genome sequence of Mycobacterium bovis BCG SL222 Sofia and phylogeny analysis with the most closely related BCG sub-strains. The full circular genome of BCG SL222 Sofia had a length of 4,370,706 bp with an average GC content of 65.60%. After 49 years of in vitro evolution in a freeze-dried condition, we identified four SNP mutations as compared to the reference BCG-I (Russia-368) sequence. BCG vaccination is of central importance for the TB elimination programs in many countries. Since 1991, almost 40 million vaccine doses of the BCG SL222 Sofia have been distributed annually through the United Nations Children's Fund (UNICEF) and the Pan American Health Organization (PAHO) to approximately 120 countries. The availability of the complete reference genome sequence for M. bovis BCG SL222 Sofia, a WHO reference reagent for the Russian BCG-I sub-strain, will facilitate the identity assurance of the genomic stability, will contribute to more consistent manufacturing, and has an important value in standardization and differentiation of sub-strains used in vaccine production. We propose to rename the sub-strain BCG SL222 Sofia to BCG-Sofia for practical and common use.

Complete Genome Sequence of Mycobacterium bovis BCG SL222 Sofia, the First WHO Reference Reagent for the M. bovis BCG Vaccine of the Russian BCG-I Substrain.

Mycobacterium bovis BCG SL222 Sofia is a substrain descending from the Russian BCG-I vaccine strain. Here, we report the complete genome sequence of BCG SL222 Sofia, which will facilitate identity assurance and will contribute to more consistent manufacturing, standardization, and differentiation of substrains used in vaccine production.

Quality control and safety assessment of BCG vaccines in the post-genomic era.

A hundred and five years ago, Albert Calmette and Camille Guérin began a daunting task, which is unmatched even today, that led to the most widely used vaccine in human history. Despite a century of scientific advances, BCG (an acronym for Bacillus Calmette-Guérin) remains the only vaccine for prevention of tuberculosis. Due to the fact that the use of BCG vaccines will continue, either as a stand-alone or as a prime vaccine in prime-boost immunization strategies, the World Health Organization (WHO) has underlined the necessity for further work toward better characterization, evaluation and quality control of the BCG vaccine, taking into account recent advances in genetics and molecular biology. The potential benefit of such improved characterization could be addressed to better and easier differentiation between sub-strains used by different manufacturers. It may help to ensure consistency of production in terms of genetic stability and it may also help the clinical evaluation of new antituberculosis vaccines. Last but not least, the state-of-the-art technologies could facilitate the quality control performed by the manufacturers and by National Control Authorities as well.