ANTIGENIC PROPERTIES 105 



1951b) and of staphylococcal phage 3A (Rountree, 1952) dis- 

 appeared during the early stages of infection. Both workers 

 observed that newly synthesized complement-fixing antigens 

 appeared and increased intracellularly a few minutes before 

 mature virus. Miller and Goebel (1954) injected lysogenic 

 cells of B. megalerium into rabbits and failed to demonstrate the 

 production of phage-specific, complement-fixing, or neutralizing 

 antibodies. Since nucleic acids have not, in general, been 

 found antigenic, this negative result, which extended an earlier 

 failure by F. Lanni (cited by LwofF, 1953), accords with the 

 current conception that prophage consists of DNA. Fodor 

 and Adams (1955) used complement fixation in analyzing the 

 antigenic relationship of T5, the related phage PB, and T5 

 X PB hybrids. Details of a photometric complement titration 

 are given by Lanni (1954). 



6. Specific Aggregation 



Schlesinger (1933a) observed the aggregation of phage WLL 

 particles by antiphage serum using the dark field microscope. 

 Burnet (1933c) demonstrated that phage CI 6 gave a visible 

 precipitate when mixed with antiserum. Photographs of the 

 aggregated phage particles, taken by Barnard with the ultra- 

 violet microscope, are included in Burnet's paper. A visible 

 precipitate was formed when antiserum was mixed with phage 

 CI 6 at all concentrations above about 2X10^ particles per ml. 

 For smaller virus particles a considerably higher concentration 

 is needed to give a visible precipitate, since the amount of 

 precipitate formed is dependent on the total mass of antigen 

 added. The relationship between the size of an antigenic 

 particle and the concentration of particles needed to give a 

 visible precipitate has been discussed by Merrill (1936). This 

 author also discussed the relationships between particle size 

 and the minimal concentration required for complement fixation 

 and for the stimulation of antibody production. These relation- 

 ships should be of considerable value to virologists. Ignorance 

 of them has been responsible for much wasted eflfort. 



