IMMUNIZATION WITH BACTERIOPHAGE SUSPENSIONS 537 



Three were injected after 24 days. All 3 resisted, 2 without loss of 

 weight, 1 lost 200 grams. 



Two were tested after 17 days. One resisted, the other died. 



Two were tested after 10 days. Both resisted, one without loss in 

 weight, the other lost 50 grams. 



Thus, of the 7 rabbits inoculated with but 0.12 cc. of bacteriophage 

 suspension, 6 resisted the inoculation of 4 fatal doses of culture. A 

 single one did not have an immunity sufficient to overcome this strong 

 intoxication. 



Sardjito then attempted to ascertain whether the bacteriophage exerts 

 an opsonic action in vivo comparable to that which I had shown to occur 

 in vitro. His results indicated that the subcutaneous inoculation of a 

 suspension of the bacteriophage increased the phagocytic power of the 

 rabbit from 100 to 200 per cent. 



These experiments upon rabbits revealed another fact which is indeed 

 difficult to understand, namely, the injection of the bacteriophage sus- 

 pensions neutrahzed in vivo the dysentery toxin 



When rabbits which had received by subcutaneous injection a surely 

 fatal dose of Shiga bacilli were given 6 hours later, also by the subcutane- 

 ous route, 1 cc. of bacteriophage suspension (one month old) 8 of the 

 11 animals survived. All 6 of the control rabbits died. In a second 

 experiment the bacteriophage was not injected until 16 hours after the 

 injection of Shiga bacilli. Here, 2 of the 6 treated animals lived. All 

 4 of the controls died. 



On the other hand, upon many occasions I have injected simultane- 

 ously the bacteriophage and the bacilli into different regions of the body 

 and I have yet to protect an animal from death in this way. Ap- 

 parently unless the bacteriophage is injected either before or after the 

 infecting injection it is without neutralizing effect. For this fact I can 

 offer no explanation. 



This distinct antitoxic action of suspensions of the bacteriophage 

 which have developed at the expense of B. dysenteriae is in some way 

 related to the phenomenon of antiphylaxis. As was stated when we 

 were considering this phenomenon it seems logical to believe that when a 

 series of injections of bacteriophage cause within the animal the develop- 

 ment of a toxic hypersensitivity it must mean that the suspensions con- 

 tain an antitoxic substance or property. There are other experiments 

 which suggest the same thing. 



Such are the experiments made up to the present time upon the im- 

 munity conferred by the inoculation of suspensions of the bacterio- 

 phage. It is to be hoped that experiments will be made on man, partic- 



