BACTERIOPHAGE AS AN ANTIGEN 391 



pure, obtained by the selective isolation method previously de- 

 scribed. These are the conclusions to which I have arrived. 



1. The antigenic value of different races of the bacteriophage is 

 extremely variable. This agrees fully with all who have worked on the 

 subject. 



2. The neutralizing action of an antiserum is by no means limited 

 to the race of the bacteriophage which served for the immunization of 

 the animal. In this point my results agree with those of Otto, Munter 

 and Winkler. 



3. An antiserum shows a specificity of virulence and not of race. A 

 serum derived from an animal immunized with suspensions of a bac- 

 teriophage developed at the expense of one bacterium inactivates the 

 virulence for this bacterium, and leaves, in general but not always, the 

 other virulences unimpaired. Otto, as well as Wolff, reached a similar 

 conclusion. 



TABLE 49 



I have further observed that an antiserum for the Shiga, Flexner, 

 or Hiss bacteriophage neutralizes the virulence for Shiga, Flexner, or 

 Hiss bacilh of almost all other races of the bacteriophage. For the 

 antibacteriophagic sera for the CoH-bacteriophage and the Typhoid- 

 bacteriophage the specificity of virulence is much less uniform, al- 

 though an action upon other races may be observed. 



5. THE BACTERIOPHAGE ANTIGEN 



With Eliava I reported^'^^ some experiments from which it appeared 

 that all races of the bacteriophage must contain a common antigenic 

 principle. As a matter of fact, any antibacteriophagic serum what- 

 ever — one prepared, for example, by injections of a Shiga-bacteriophage 

 —contains a sensitizer which causes the fixation of alexin in the pres- 

 ence of a suspension of bacteriophage of any race whatsoever, such as 

 a Plague-bacteriophage.* 



* Detailed protocols of these experiments have been presented in The Bac- 

 teriophage, Its Role in Immunity. It is unnecessary to repeat them here, for 

 reasons which are obvious. 



