Alteration of Pasteurella pestis Bacteriophage Following Successive Transfer on Pasteurella pseudotuberculosis and on Shigellae

Abstract

P. pestis bacteriophage lysed 31 of 40 strains of P. pseudotuberculosis. After repeated transfer on one of these (Spokane strain), it also lysed the remaining 9 strains. It was then transferred on Shigella dysenteriae and reverted to its original activity; i.e., it again failed to lyse the 9 strains of P. pseudotuberculosis resistant to the original phage. Activity for all strains was restored by transferring it again on the Spokane strain. Transfer of phage able to lyse all strains on S. paradysenteriae, S. sonnei, and S. ambigua caused no reversion to the original selective activity for only 31 strains. Plaques did not change in size.