VIRAL FUNCTIONS: ORDER AND DISORDER 



possesses and perpetuates the potentiality of producing bacterio- 

 phage particles in the absence of infection. When this potentiality 

 is not expressed, the bacterium grows and divides. When it is 

 expressed, it dies. The bacteria that perpetuate the possibility 

 of producing bacteriophage in the absence of infection are called 

 lysoge7iic. 



The prophage. A given bacterial species can be infected by a 

 number of different strains of temperate bacteriophages, let us say 

 A or B, which might differ by a number of properties such as host 

 range, immunological specificity, size, shape, etc. A given bacterium 

 infected and lysogenized by a temperate bacteriophage A will 

 perpetuate the potentiality to produce bacteriophage A. When 

 infected with B, it will perpetuate the potentiality to produce B. 

 The lysogenic bacterium multiplies a specific structure: the prophage 

 (etymologically, "before the phage"). 



A number of experimental data have led to three essential con- 

 clusions (Figure 28). 



CDnon-lysogenic b ( [ 



Productive 

 infectio 



>*/ — i 



:'c^ 



^g^ 



CHD 



Vegetative 



phase [^~:cc:<-J 



>{Em^ 



Figure 28. Diagrammatic Representation of Lysogeny (after Lwoff, 

 1953). 



[69] 



