Mapping the phylogeny and lineage history of geographically distinct BCG vaccine strains. BCG vaccine strains

The Bacillus Calmette–Guérin (BCG) vaccine against tuberculosis (TB) has been in use for 100 years and it still currently the only widely available vaccine against TB. Since it was developed, BCG has been disseminated to different laboratories around the world, where differing culture methods and storage have developed genetically distinct strains over time. Differing vaccine efficacy of BCG around the world is well documented and it has been hypothesised that these genetic differences contribute to this variation, although the picture is complex. Here we utilised a historic archive of BCG vaccine strains to address this hypothesis.