THERAPEUTIC IMMUNIZATION IN MAN 517 



testis with cultures has thus far failed to protect rabbits against 

 subsequent inoculation with virulent material, and passive immuniza- 

 tion with sera produced with "culture" pallida has been without 

 effect. 



From all this it appears that the "culture" treponema has.im- 

 munologically no relation to the virulent organism. It has lost its 

 virulence completely, as six and more successive inoculations into 

 rabbit testes have sufficiently demonstrated to us. 



The sera produced by many injections of dead and living culture 

 organisms have no effect whatever on the virulent organisms in vitro, 

 and vaccination with it does not protect against subsequent infection. 



The luetin reac ion is the only method by which the relationship 

 between the two is demonstrable at all, and there too, we have to 

 reckon with what is generally spoken of as the non-specific increased 

 sensitiveness of the syphilitic skin. 



Were it not for the production of lesions with cultures in their 

 early test tube generations by Hoffmann 175 and by Noguchi in a few 

 experiments, one would be almost in doubt as to the identity of the 

 virulent with the culture organisms. 



The reactions in syphilis between the invading microorganism 

 and the invaded subject thus differ in certain fundamental premises 

 from those prevailing in diseases caused by most bacteria. The 

 treponema pallidum is an organism which, unlike many bacteria, is 

 rarely subjected to the necessity of adapting itself to extra-corporeal 

 existence during the interval between its passage from one host to 

 another. It practically always infects directly, being inoculated from 

 one human being to the next and has in consequence developed a very 

 delicate parasitism not unlike that seen in certain trypanosome 

 diseases of rats and that which we ourselves have observed in the 

 well-known spirochete infections of white mice. A considerable 

 percentage of laboratory white mice have been found to harbor 

 actively motile spirochetes, often in considerable numbers in the 

 blood and peritoneal fluid without there being any objective signs of 

 illness in the animals. It is an instance of what has been spoken of 

 by Bail as "infection without disease," and approaches what biolo- 

 gists speak of as symbiosis, except that the host in this case does not 

 benefit in any way by the invasion. Even in the case of the mice, 

 a certain amount of gradual injury, perhaps only metabolic, by the 

 slow removal of nutritive material, is taking place. In syphilis the 

 mutual adaptation may perhaps be less complete, a sufficient accumu- 

 lation of the invaders and especially a mechanical injury of tissue 

 cells, of closing of tissue spaces together with a certain amount of 

 toxic action, leading eventually to pathological changes. 



The virulent treponemata apparently do not arouse true antibody 

 formation in any marked degree. When they have been cultivated 



175 Hoffmann, W. H. Deutsch. med. Wchnschr., 1911, xxxvii, 1546. 



