360 S. GAED AND O, MAAL0E 



1. General Aspects 407 



2. Oxygen 408 



3. Hydrogen Peroxide 409 



4. Halogens 410 



E. Alkylating Agents 411 



F. Organic Solvents 412 



G. Enzymes 414 



H. IMiscellaneous Agents 417 



References 418 



I. Introduction 



There is only a small step from the subject of the preceding chapter to 

 that of the present. Each new method by which the biological activities of 

 a virus can be registered widens the area open to experimentation; usually, 

 the first and simplest experiments to be carried out are concerned with 

 the stability of the virus. We want to know under what environmental condi- 

 tions the activities we register are preserved and how we can interfere with 

 or destroy them in a controlled manner. Such questions are of obvious interest 

 from theoretical as well as practical viewpoints. 



A great variety of treatments and agents are known to inactivate viruses 

 and, during inactivation, the individual biological activities of the virus tend 

 to disappear one after the other. We shall restrict the treatment of this mani- 

 fold phenomenon in two ways: in the first place, emphasis will be on the most 

 important and, generally, the most sensitive property of the virus particle, 

 its infectivity. We shall therefore leave out studies of noninfective, virus-like 

 particles, and treat inactivation of such virus manifestations as interference 

 or hemaggultination in less detail. Second, we propose to deal exclusively 

 with free virus particles and not consider the effects of inactivating, or 

 inhibiting agents on virus cell complexes. 



Even with these restrictions our subject matter is large and heterogeneous. 

 The other obvious subdivision, according to the physical, physicochemical, 

 or chemical nature of the inactivating treatment, or agent, that has been 

 adopted is not altogether satisfactory. In some cases it would have been more 

 natural to treat inactivation for the sake of obtaining sterility separately 

 from those experiments in which the process of inactivation is studied in 

 order to gain information about the structure of the virus particles themselves. 

 In other cases, the presentation might have been based on the mechanism by 

 which inactivation is thought to occur. However, neither of these alternative 

 classifications is practicable. The first, because many agents are important 

 from practical as well as theoretical viewpoints. The second, because, very 

 often, the structural changes involved in inactivation are poorly understood. 



Two special types of inactivation: neutralization by antibodies, and block- 



