250 



HEINZ SCHUSTER 



TABLE III 



The Particle Weight and RNA Content of Some Animal Viruses 



Virus 



Particle weight 



RNA content 



(in % of the 



particle 



weight) 



RNA 



'molecular 

 weight"" 



Poliomyelitis 

 Equine encephalitis 

 Mixoviruses 



Influenza type A 



Fowl plague 



Newcastle disease 



6.7 X 10 6 

 50 X 10 6 



280 X 10 6 

 150 X 10 6 

 800 X 10 6 



22-30 

 4.4 



0.7-1.0 



1.8 

 4 



-2 X 10 6 



-2 X 10 6 



-2 X 10 6 



-2 X 10 6 



-32 X 10" 



° Compare footnote in Table I. 



TABLE IV 

 Base Composition of the RNA of Various Animal Viruses" 



Source of nucleic acid 



Bases of nucleic acid 

 (mole % nucleotide) 



Adenine Guanine Cytosine 



Uracil 



Poliomyelitis 

 Influenza A 



PR 8 



MEL 



WSE 



Swine 



CAM 

 Influenza B 



LEE 



MIL 



ROB 



30.4 



25.4 



19.5 



24.7 



° Taken from W. Schafer, in "The Viruses" (F. M. Burnet and W. M. Stanley, eds.), Vol. I, p. 475. Aca- 

 demic Press, New York, 1959. 



Until recently, it was most difficult to prepare sufficient quantities of 

 purified animal viruses. Improvements in methods of cultivation and puri- 

 fication have made it possible to determine the RNA content and base com- 

 position of several animal viruses. The pertinent data are presented in 

 Table IV for polio virus and influenza virus. The RNA of unrelated sero- 

 types, influenza A and B, seems to have different base compositions; B 

 strains have less guanine and more uracil than A strains. It is not clear 

 whether these differences are highly significant and, therefore, Ada 6 com- 



