CHAPTER 9 



Radiation and Viruses* 



S. E. LURIA 



Department of Bacteriology, University of Illinois 

 Urbana, Illinois 



Introduction. Effect of radiations on virus infectivity: Ionizing radiations — Ultra- 

 violet radiation — Visible light. Differential effect of radiations on various properties of 

 viruses: Nonlethal effects — Separation of properties of inactive virus particles. Irradiated 

 virus in multiple and mixed infection: Interference phenomena — Reactivation phenomena. 

 Intracellular irradiation of viruses: Irradiation of cells infected with exogenous viruses — 

 Radiation and latent viruses. References. 



1. INTRODUCTION 



To few fields of biology have radiation studies contributed as much as 

 they have to virology. The reasons are to be found in the properties of 

 viruses and in the methodology of virus research. A virus can be defined 

 as a submicroscopic entity capable of self-reproduction after exogenous 

 infection of specific Uving cells (Luria, 1950). According to host, viruses 

 may be classified as animal viruses, plant viruses, and bacterial viruses or 

 bacteriophages. In their extracellular state, virus particles have charac- 

 teristic sizes and chemical compositions, a common feature of which is the 

 presence of protein and of nucleic acid of either the ribose or the deoxy- 

 ribose type. Their small size, nucleoprotein content, and ability to 

 reproduce inside cells make them useful models for the study of repro- 

 duction of genetically specific biological units. At the same time they 

 offer unique opportunities for observation both in the resting, extra- 

 cellular state, in which they can be submitted to a variety of treatments, 

 and in the reproductive, intracellular state, in which they behave as com- 

 ponents of an integrated cellular system. Radiations, because of the 

 discrete nature of their action, are more useful than chemicals in affecting 

 free virus in such a way that, upon reintroduction into a host, the host- 

 virus interaction will be abortive or variously modified; the results are 

 very informative as to the biology of viruses. Moreover, it is possible by 



* This chapter has not been revised since being wyitteji in 1951. Vakiable discussion 

 and bibliography of more recent work are given by Pollard (1953). 



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