BEHAVIOR OF BACTERIOPHAGE IN DISEASE 485 



7. THE BACTERIOPHAGE IN TYPHUS EXANTHEMATICUS 



Having learned from the above brief discussion of the behavior of the 

 bacteriophage in colon bacUlus infections that under certain circum- 

 stances the bacteriophage may assume a new and distinctive role in the 

 origin of an infectious process, let us now turn to an entirely different 

 disease, typhus fever, where we will discover still another aspect of the 

 complex question of the bacteriophage and bacteriophagy. 



For our knowledge of the behavior of the bacteriophage in this disease 

 Fejgin^oi'^os is largely responsible. She began by isolating a bacterio- 

 phage from an old strain of B. proteus Z19. The virulence of this race 

 she enhanced by repeated passages. In studying the mutant strains 

 of B. proteus which form in secondary cultures* she found that filtrates 

 of these cultures often became turbid because of the development of 

 bacteria identical with the mutant forms previously studied. 



Continuing with the problem, she injected guinea pigs with the clear 

 filtrates and found that animals so inoculated presented the same 

 thermic reactions as did guinea pigs inoculated, either with the blood 

 of patients with typhus exanthematicus, or with virulent materials 

 derived from passage guinea pigs. Such a finding is of extreme interest, 

 but her next observation is still more strange, for she found that guinea 

 pigs injected with these filtrates were thereafter immunized against 

 injections of virulent materials, whether the latter were derived directly 

 from a patient with typhus fever or from passage guinea pigs. Recip- 

 rocally, a guinea pig which had reacted to the typhus material was 

 refractory to the filtrates of the B. proteus Z19 bacteriophage. 



And, as though to add further interest to these results, she found that 

 from guinea pigs bled on the 3rd or 4th days of the febrile period which 

 followed the injection of a filtrate she could isolate from the blood and 

 from the organs (using the egg medium of Besredka under anaerobic 

 conditions) the same mutant forms as she had previously recovered, 

 either from the cultures which developed in the filtrates or from the 

 organs of guinea pigs inoculated with material derived from patients 

 having typhus fever. 



As I stated above, if these studies are confirmed, — and it seems, 

 indeed, that this work of Fejgin was carefully done,^ — they will explain 

 both the etiology of typhus exanthematicus and the relation which 

 exists between the agent of this disease and B. proteus X19. 



* We have considered the studies of Fejgin on the mutant forms in an earlier 

 chapter. 



