192 THE PHYSICS OF VIRUSES 



(i). They are always nucleoprotein. 



{2) . They are roughly 25 % nucleic acid and 75 % protein, with 

 wide variations possible. 



iS). They attach electrostatically to the host in the case of 

 bacterial viruses. Co-factors may be needed. 



{If). They enzymatically confirm their entry into the bac- 

 terium. 



(5). Not all the protein enters, the sulfur-containing part re- 

 mains outside. 



(6). Bacterial metabolism is rapidly shifted to viral metabo- 

 lism after entry. 



(7). The timetable for T-1 is such that 300 new units are 

 formed in 13 min. 



{8). About 1,000 surface specific antigens exist.^ 



{9). Polypeptide absorbed ultraviolet light is less effective in 

 causing virus inactivation. Nucleic-acid absorbed light has the 

 maximal effect. 



{10). Damage by heat, ultraviolet light, and X-ray or deu- 

 teron bombardment can lengthen the latent period. 



{11). Multiple infection by ultraviolet inactivated virus par- 

 ticles can cause reconstitution and growth of virus. 



{12). Ultraviolet inactivated virus becomes reactivated to 

 some extent by visible light while in the bacterium. 



{13). About 50 units are responsible for shortening the latent 

 period. 



{IJi). Genetically complete virus particles are formed and 

 multiply by something akin to division. 



{15). Genetically complete virus particles can exchange ge- 

 netic units very rapidly among several particles. 



{16). Mutants which recombine have the same serological 

 behavior. 



{17). No cross reaction between phage antisera and bacterial 

 antisera exists. 



Description of Present Knowledge of Virus 

 Multiplication 



Putting together a story from the summary just given we can 

 see it as follows. The virus is a completely inert, "physical" 



