PubMed · 5576117
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K O Jensen. 1971-03-31. [Modern tuberculosis control].. https://pubmed.ncbi.nlm.nih.gov/5576117/
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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 (IS6110-2/mpt64+), 1926-31 (IS6110-1/mpt64+), and 1931 or later (IS6110-1/mpt64-) This analysis demonstrates that BCG has undergone genetic changes since 1921, consistent with ongoing in-vitro evolution.
In order to validate two new lots of Mérieux BCG vaccine (Mérieux seed derived from strain 1072), a calibration study was performed to compare their safety and immunogenicity to a full dose of the WHO-reference BCG vaccine (Tokyo strain 172) as well as the WHO-reference vaccine given at 1/10 of its normal concentration, in an open, randomized, four-arm, multicenter study in Senegal. A total of 1041 healthy Senegalese children aged 8-10 years were screened for participation in this study, of whom 548 had a negative Mantoux test and complied with inclusion and exclusion criteria. These children were randomly allocated a single dose of one of the following vaccines: full-dose Mérieux BCG vaccine (lot E0650); full-dose Mérieux BCG vaccine (lot E0624); full-dose WHO-reference vaccine (Tokyo strain 172); or 1/10 dose WHO-reference vaccine. A follow-up examination, including a tuberculin test, was performed 10-12 weeks after BCG vaccination for 465 (85%) children: 236 Mérieux BCG vaccine (117 lot E0650; 119 lot E0624); 115 full-dose WHO; 114 1/10 dose WHO. The percentage of subjects with a positive tuberculin test after vaccination was significantly lower (P < 0.001) in the 1/10 dose group (81.5%) compared to the other three groups (> 96%). The mean induration diameter was significantly smaller in subjects who received the low-dose of WHO vaccine compared to the others, according to analyses considering all subjects vaccinated, as well as only those subjects with a positive tuberculin test after vaccination. More children in the low-dose group did not have a vaccination scar, and the mean diameter of scars was smaller in this group. The rate of tuberculin reactions, the classification of reactions (Palmer and Edwards), and the characteristics of the vaccinal lesion were similar for the Mérieux BCG vaccines and the full-dose WHO-reference vaccine. All vaccines were safe, as evidenced by the absence of adenitis or suppurative adenitis during the course of the study. Results from this trial show that the two lots of Mérieux BCG vaccine behave equally as well as the full-dose WHO-reference BCG vaccine. The WHO-reference vaccine, given at 1/10 of its normal concentration was significantly less immunogenic, according to all parameters evaluated.
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