RESUMO
An unusual principle has been observed: when obliged to reproduce in a new medium ill-adapted to their development, mycobacteria abandon their common mode of reproduction--transversal division--and adopt a mode of evolution that puts less of a strain on their vitality: the long evolutive cycle, first described in 1899. In an initial step, the mycobacilli used for seeding purposes undergo auto-bacteriolysis, creating a cyanophilous fundamental substance which is in fact a symplasm due to the ex-bacillary microgranules, a multitude of independent and mobile genes. These genes merge according to a new and simpler arrangement: thus are formed the slender cocci that take the place of the amorphous cyanophilous substance. These cocci, released in the culture, multiply and lengthen into bacilli which merge to form a new amorphous cyanophilous substance. This new amorphous cyanophilous substance, thanks to another rearrangement of its genes, then forms a "crust" which undergoes exfoliation and crumbles into alcohol-acid-fast (a.a.f.) bacilli. Coryneforms and a.a.f. bacilli (mycobacteria) constitute two distinct agents with different and even occasionally opposite pathogenicities, as can be observed in co-cultures of Coryneforms (Hansen's bacillus or bacillus Calmette-Guérin) and tubercle (Koch's) bacillus. In such co-cultures, the tubercle bacilli progressively lose their vitality and virulence while, inversely, the Coryneforms reinforce their pathogenicity. Co-cultures of BCG and lepromin thus constitute an association with a particular property and most likely an auto-vaccinating activity against leprosy which is the subject of on-going research.
