Leptospires colonial variations.

Six of 12 relatively freshly isolated and museum strains representing serovars mozdok, monjakov, kazakhstanica I and patoc were heterogeneous in colonia morphology. Recloned colonial variants of one and the same heterogeneous population did not exhibit any differences in antigenic properties in cross reactions of microagglutination and absorption of agglutinins. Along with it among the clones with various colonial types of the two relatively freshly isolated strains of serovar mozdok distinctions in virulence (LD50) for hamsters were marked. Moreover for the clones one of them differences in the level of renal infection (ID50) and in morphology of the cells (hooked and straight) were found. In a solid Tween-80 albumin medium in populations of two colonial variants (serovars monjakov and kazakhstanica I) colonial mutants appeared without any changes in antigenic properties, virulence and cell morphology with frequency of 10-9-10-8 per one bacterium per one generation.