APPENDIX 461 



Preparation and Use of Antiphage Sera 



Antibodies against viruses have the general property of re- 

 acting with the viruses to form an antibody- virus complex 

 which is noninfectious for the host cell by virtue of the fact that 

 adsorption of virus to host cell is prevented. The virus is not 

 damaged by combination with antibody, as demonstrated by 

 the fact that treatment of the virus-antibody complex with 

 papain will result in destruction of antibody and recovery of 

 infectivity of the virus. 



Example: In a typical experiment (Kalmanson and Bronfenbrenner, 1943), 

 a sample of phage T2 was incubated with antiserum at a final dilution of 1 : 1,000 

 for 1 hr. at 37° C, at which time 90 per cent of the infective particles had been 

 neutralized. The neutralized phage was then diluted 1 :100 in activated pa- 

 pain and incubated at 37° C. Within 20 min. the neutralized phage was 

 completely reactivated. In a control experiment using inactive papain there 

 was no reactivation of phage. The papain solution contained 4 g. of commer- 

 cial papain/liter of saline and was activated just before use by addition of 0.1 

 ml. of 16 per cent cysteine-HCl/5 ml. of papain solution and adjustment of pH 

 to 7.4. 



Antibodies against viruses are extremely useful tools in virus 

 research since they furnish a convenient means for identification 

 of viruses. They permit serologic classification of the viruses 

 into groups in which the antigenic relationships are correlated 

 with morphologic and biologic resemblances (Delbriick, 1 946a) . 

 Since antibodies against phages do not inhibit the infectious 

 process once the virus has become adsorbed to the host cell 

 (Delbriick, 1945b), but do prevent further adsorption of free 

 phage, they enable the investigator to, in eflfect, remove un- 

 adsorbed virus from the scene of action without interfering 

 with the growth of adsorbed virus. 



Immunization of Animals 



The production of a high titer antiserum against a bacterial 

 virus diflfers in no essential respect from procedures for im- 

 munization against bacterial antigens. The important con- 

 siderations are to inject enough antigen to provide an adequate 



