ANTIGENIC PROPERTIES 99 



body response from one rabbit to another, it may be desirable 

 to immunize at least three rabbits with the same phage prep- 

 aration. Judged by the neutralization test, antisera prepared 

 against certain phages, such as T2, T3, T4, T6, and T7, usually 

 have very high homologous antibody titers in comparison with 

 antisera against others, such as Tl and T5, which may be rela- 

 tively weak. Such differences do not necessarily reflect corre- 

 sponding differences in antibody concentration, since the rate 

 of neutralization may easily depend on other factors as well. 

 Actually, a very few determinations have been made of the 

 absolute antibody content of antiphage sera. 



The effect of adjuvants on phage antigenicity has been very 

 little studied, probably because most phages are already ex- 

 cellent antigens. Wahl and Lewi (1939) obtained a marked 

 improvement in the antigenicity of a low-titer B. suhtilis phage 

 by adsorption to alumina. Intraperitoneal injection of 3 X 

 10^ particles of unadsorbed phage gave little or no antibody 

 response. Injection of the same amount of absorbed phage re- 

 sulted two weeks later in an antiserum giving 90 per cent in- 

 activation at a dilution of Vsq. The titer increased to V200 in 

 a month. This technique may be useful to workers dealing 

 with low-titer temperate phages. 



Phages retain antigenicity, in some instances without appre- 

 ciable loss, following careful inactivation of their infectivity by 

 heat, formaldehyde, ultraviolet irradiation (Muckenfuss, 1928; 

 Schultz, Quigiey, and Bullock, 1929; Nagano and Takeuti, 

 1951; Pollard and Setlow, 1953; Miller and Goebel, 1954); 

 phenol, photodynamic action of methylene blue (Burnet, 

 Keogh, and Lush, 1 937) ; osmotic shock, and sonic vibration 

 (F. Lanni and Lanni, 1953; Nagano and Oda, 1954). Phage 

 which has been "overneutralized" by homologous antibody is, 

 however, nonantigenic in guinea pigs, even after treatment with 

 papain (Kalmanson and Bronfenbrenner, 1943; Nagano and 

 Takeuti, 1951). 



The antigenicity of premature lysates of a staphylococcal 

 phage has been studied by Rountree (1952); of purified T2 



