VIRAL FUNCTIONS: ORDER AND DISORDER 



Some are able to manufacture the proteins of the phage. In others, 

 the synthesis of one or more of these proteins is impossible, and the 

 genetic material of the phage, so far as is known, is not multiplied. 

 It seems as though the vegetative phase could be characterized 

 by a sequence of events. Each event has to be completed so that 

 the following one can be initiated. And apparently, in the absence 

 of protein synthesis, the chromosome of the defective bacteriophage 



Table VII. Defective Prophages. 



is unable to multiply vegetatively. The autonomous multiplication 

 of the viral genetic material seems to depend on the expression of a 

 certain number of viral functions, perhaps on a sequence of functions. 



In a defective prophage, the capacity to multiply as an autonomous 

 unit may be altered. But the genetic alteration does not affect the 

 ability to multiply as prophage, that is, as an integrated unit. When 

 it is attached to the bacterial chromosome, the genetic material of 

 the defective phage is submitted to the bacterial system of control 

 and multiplies despite its genetic defects that affect only autono- 

 mous multiplication. 



Let us recall that in a normal lysogenic bacterium the expression 

 of the viral functions of the prophage is repressed. The hypothetical 

 repressor prevents also the expression of the functions of superin- 

 fecting homologous bacteriophage. As a consequence, the genetic 

 material is unable to multiply autonomously. 



In a lysogenic strain, the initiation of the vegetative phase and 



[79] 



