1 52 BACTERIOPHAGES 



formaldehyde, ethylene oxide, ethanol, periodate, thymol, 

 chloroform, heat, sonic vibration, and osmotic shock, and were 

 then tested for their ability to adsorb phage. In all cases the 

 adsorption of phage T3 is very quickly lost whereas the ability to 

 adsorb T7 is scarcely impaired. The adsorption of T4 is 

 markedly decreased following treatment with heat and ethvlene 

 oxide. Killing of the bacteria with moderate doses of ultra- 

 violet light does not affect the adsorption of any of the phages but 

 heavier doses selectively inactivate the T3 receptors. It is 

 evident that the receptor for T3 is markedly labile to all the 

 agents tested and that these experiments give no clue to the 

 chemical nature of the receptor sites other than to emphasize 

 that the sites for various phages are different. 



Similar experiments on strain B of E. coli were performed by 

 Weidel (1953a). Formaldehyde decreases the activity of the 

 receptors for Tl, T3, T5, and T7 but not for T2, T4, and T6. 

 Periodic, nitrous, and other weak acids destroy the receptors for 

 Tl, T3, T4, T5, and T7 but not for T2. Sodium hydroxide 

 (A^/60) removed the T5 receptor from the bacterial surface with- 

 out affecting the T2 receptor. Weidel notes the unusual stabil- 

 itv of the T2 receptor; "means to destroy it specifically have 

 not yet been found." However, Tolmach and Puck found that 

 T2 receptors are destroyed by CH3OH -}- HCl without inactiva- 

 tion of the Tl receptors. Further work along these lines with 

 more specific chemical reagents may be well worth while. 



If phage particles attach to antigenic substances on the bac- 

 terial surface (Chapter IX), one might expect that bacterial ex- 

 tracts containing soluble antigens should react with the phage 

 particles to interfere with adsorption. Early attempts to test 

 this possibility met with failure because of faulty concepts of the 

 nature of the bacterial antigens. Because in many cases the 

 immunological specificity is due to a polysaccharide hapten, the 

 efforts of immunochemists were devoted to the isolation of the 

 polysaccharides in pure form. When these were tested for 

 phage neutralizing activity they were usually found to be inert 

 (Burnet, 1934b). It was later found that the phage-inactivating 



