Isolation of revertants from antigenic variants of leptospiras.

The revertants were isolated from the antigenic variants of Leptospira interrogans serovar copenhageni Shibaura by plating the variants on the solid medium containing the homologous immune serum, and by noting the growth of small colonies. The revertants which produced the small colonies were antigenically identical with the parents. The variants which retained their antigenicity for 2 to 3 years produced only a small number of revertants. On the other hand, the variants which phenotypically changed to the parent during the same period of maintenance produced many revertants. The revertant-clones and the variant-clones showed a similar generation time. No revertant was isolated from the variants of hebdomadis Hebdomadis.