Chemical Inhibiflon of Viruses 15S 



all cases adequately studied (22, 28, 29), as with bacteria 

 and phages. Development of required precursor materials 

 or of incomplete or immature virus particles in advance of 

 infective particles has not been decisively demonstrated 

 (28, 34), as with phage. Recent studies with influenza 

 virus indicate that when cells are not overloaded by very 

 large inocula, only mature infective particles are produced 

 during reproduction (28). 



Both the rate of reproduction and the amount of virus 

 produced are related to oxidative metabolism of the host 

 tissue, and if this is affected, virus multiplication is dimin- 

 ished correspondingly (3, 16). Apparently, depression of 

 almost any metabolic function of the cell, however 

 achieved, results in a depression in virus reproduction. 

 Although evidence of this kind indicates that the virus re- 

 quires the presence of an actively metabolizing cellular 

 environment, it does not point to any particular biosyn- 

 thetic process as necessary for reproduction. Moreover, 

 such evidence does not prove that the virus is multiplied 

 by the cell. 



If animal virus particles do not enter the cell as intact 

 particles, as is thought to be the case with bacteriophages 

 (25, 26, 31, 40), and only their nucleic acids and genetic 

 machinery are required to set the stage for intracellular 

 reproduction, it is apparent that the process is widely dif- 

 ferent from the multiplication of other microbial species. 

 The indications that the process is different are based on 

 very thin evidence with animal viruses. The evidence most 

 commonly invoked is the apparent disappearance of most 

 of the infective particles shortly after inoculation (21, 24). 

 To explain this phenomenon on a simpler premise, it is 

 necessary to assume merely that the forces which hold an 

 intact virus particle and intracellular components together 

 are considerably greater than those between the free virus 

 and the cell surface. Indications that there are strong forces 

 binding some animal viruses to cell fragments have been 



