282 BACTERIOPHAGES 



4. Abortive Infection 



The term abortive adsorption (Benzer, 1952) or abortive in- 

 fection (Benzer and Jacob, 1953; Gross, 1954a) refers to the 

 tendency of bacteria, infected or held under conditions in which 

 growth of phage is arrested, to lose the capacity to produce phage 

 when transferred to normally favorable conditions. To pre- 

 serve the singularity of the phenomenon one excludes from 

 consideration those conditions, such as high temperature, that 

 destroy bacteria or phage separately. Numerous examples are 

 described by Adams (1954, 1955) and Northrop (1955a) and 

 some have already been referred to in this chapter. We discuss 

 here only a few examples that are at least partly understandable. 



The abortive infection of bacteria by phage T2 in the presence 

 of proflavine has already been described. Since proflavine 

 blocks phage growth without preventing bacterial lysis, the loss 

 of capacity to produce phage is to that extent explained and is 

 not in itself very interesting. 



A difTerent kind of abortive infection is observed when T5 

 adsorbs to bacteria in the absence of calcium (Adams, 1949b). 

 In this case the absence of calcium prevents injection (Luria and 

 Steiner, 1954). Bacteria held in the calcium-free medium 

 gradually lose their capacity to produce phage on subsequent 

 addition of calcium (Adams, 1949b). The infected bacteria 

 undergo cytological changes and are unable to multiply (Chapter 

 XII). These results may be summarized by saying that adsorp- 

 tion of phage under conditions in which injection fails causes 

 damage to the bacterium which may prevent subsequent injec- 

 tion when the conditions are changed or, if injection is not irre- 

 versibly prevented, the capacity to produce phage is nevertheless 

 irreversibly lost. This effect of noninjecting phage recalls the 

 eflfects of T2 ghosts on bacteria (Chapter V) and other types of 

 evidence for cellular damage at the time of infection (Chapter 

 XI). 



In other instances the progressive loss of capacity to produce 

 phage is subject to nutritional control. Bacteria infected with 

 phage in the presence of cyanide may lose productive potential 



