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A historical and molecular phylogeny of BCG strains

Authors
Journal
Vaccine
0264-410X
Publisher
Elsevier
Publication Date
Volume
17
Identifiers
DOI: 10.1016/s0264-410x(98)00277-1
Keywords
  • Bcg
  • Tuberculosis
  • Dna-Fingerprinting
Disciplines
  • Biology

Abstract

Abstract Bacillus Calmette-Guérin (BCG) is the name given to a family of vaccines derived in 1921 by the in-vitro attenuation of Mycobacterium bovis. Subsequently, BCG seed lots were distributed globally, and both phenotypic and genotypic differences between strains have been described. As a step to understanding BCG diversity, we have reviewed the English and French historical record on 13 strains and DNA was extracted from these strains for restriction-fragment-length-polymorphism study. The written record suggests “early strains” obtained from the Pasteur Institute between 1924 and 1926 and “later strains” obtained after 1931. Molecular typing resulted in 3 clades, based on variability in IS6110-typing and the presence of mpt64 gene. With two exceptions, these clades correspond with strains obtained in 1924–26 (IS 6110−2 / mpt64+), 1926–31 (IS 6110−1 / mpt64+), and 1931 or later (IS 6110−1 / mpt64-) This analysis demonstrates that BCG has undergone genetic changes since 1921, consistent with ongoing in-vitro evolution.

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