Effect of the method of preparation of Bacille Calmette-Guérin (BCG) vaccine on the properties of four daughter strains

Samples of Bacille Calmette-Guerin (BCG) vaccines from four collaborating production laboratories, each of which had prepared vaccine from four different daughter strains of BCG, had previously been monitored for changes in colony morphology and the present study was undertaken to determine whether the changes observed were reflected in the patterns of protein secretion and lipid content. In the samples examined there was evidence for a correlation between colony morphology and the presence or absence of mycoside B. As the components of BCG that determine virulence and protective immunity are unknown, care must be taken to ensure constancy of the strains during the manufacture of vaccines.