J. BRONFENBRENNER 529 



BACTERIOPHAGE AS A SPECIFIC ANTIGEN 



It has just been suggested that the particles seemingly endowed with the power 

 of initiating transmissible lysis may not represent autonomous "corpuscles" of a para- 

 site, but serve merely as a vehicle on which the active principle is adsorbed. The ac- 

 tive agent itself, however, may still be particulate, i.e., may consist of minute aggre- 

 gates composed of a number of molecules each, and these small aggregates may still 

 possess all the characteristics previously ascribed to larger carrier-particles. These 

 aggregates, though perhaps considerably smaller than 20 n^x in diameter, may still 

 represent, according to the definition of D'Herelle,' "colloidal micellae which differ 

 from other forms of hfe only in their size." That the active agent may not be a crys- 

 talloid is suggested, for instance, by its behavior with respect to solubility. Once 

 dried, the preparations of bacteriophage cannot be brought to the state of initial dis- 

 persion in water. This is particularly true of purified preparations of bacteriophage 

 deprived of all, or nearly all, of the extraneous material.- The colloidal nature of the 

 active agent is further evidenced by the fact that it acts as an antigen and causes 

 the production of specific antibodies when introduced parenterally into experimental 

 animals.' While the antisera thus obtained are capable of neutralizing the activity 

 of the bacteriophage, they usually show simultaneously the presence of agglutinins, 

 opsonins, precipitins, and complement-fixing antibodies for homologous bacteria.^ 

 Moreover, purely antibacterial sera apparently possess the power to inhibit the prog- 

 ress of lysis by homologous bacteriophages.^ In spite of the inference suggested by 

 these findings, it has been possible to establish that the active principle possesses in- 

 dependent (autonomous) antigenic value. Thus, when sera prepared by immuniza- 

 tion with filtrates of lysed cultures are absorbed with homologous bacteria, they no 

 longer react with bacteria and their products, but retain their power to neutralize 

 the bacteriophage unimpaired.'' If the filtrates of lysed cultures are purified by re- 

 moval or digestion of bacterial protein, leaving only the active principle, the anti- 

 sera obtained by immunization with such purified preparations do not react with 

 bacteria, while they do neutralize the phage.' Moreover, in the case of phages capable 

 of acting on several related species of bacteria, the antigenic specificity of the fil- 



' d'Herelle, F.: Ccntralbl.f. Baklcriol., Orig., 96, 385. 1926. 



2 Bronfenbrenner, J.: Proc. Soc. Expcr. Biol, br Med., 24, 372. 1927. 



JBordet, J., and Ciuca, M.: Compt. rend. Soc. de bio!., 84, 278. 1921; Watanabe, T.: Ztsclir. f. 

 Immumtdlsforsch., u. exper. Therap., 37, 106. 1923; Sonnenschein, C: Deutsche med. Wchnschr., 51, 

 1434. 1925; Asheshov, I. N.: Compt. rend. Soc. de bioL, 93, 1327. 1925; 0?umi, S.: Ztschr. f. Im- 

 mimitdtsjorsch. u. exper. Therap., 40, 261. 1924. 



"Bail, O.: Wicn. klin. Wchnschr., 34, 447. 1921; Weiss, E., and Arnold, L.: /. Infect. Dis., 34, 

 317. 1924. 



5 Bail, O.: loc. cit.; Marcuse, K.: Ztschr. f. Ilyg. n. Infektionskraukh., 105, 17. 1925; da Costa 

 Cruz, J.: Compt. rend. Soc. de bioL, 95, 1457. 1926; Hauduroy, P.: ibid., 87, g06. 1922. 



U'on Preisz, H.: loc. cit.; Weiss, E., and Arnold, L.: loc. cit.; da Costa Cruz, J.: loc. cit. 



1 Bordet, J., and Ciuca, M.: Compt. rend. Soc. de bioL, 84, 276. 1921; Arnold, L., and Weiss, E.: 



loc. cit., 37, 411. 1925. 



