Inactivation of bacteriophage after irradiation.

Abstract

Viruses exposed to ionizing radiations or to ultra-violet light have been found by numerous experimenters to survive in accordance with a “one-hit” or “monotopic” (Gray, 1951) type of action, the survival curves being of exponential form (cf. Lea, 1946). The effects of irradiating bacteriophage S13 have been studied by various workers (Lea and Salaman, 1946; Wollman and Lacassagne, 1940), and in all cases experimental results accorded with the hypothesis that inactivation could result from the occurrence of a single ionization within the phage particle. In these experiments the conditions were such that only the ionizations occurring within the phage particles were effective. In very dilute phage suspensions, on the other hand, freed as far as possible from extraneous organic material, most of the effect of irradiation is due to ionizations taking place in the suspending medium, the phage reacting with the decomposition products of the irradiated water. If this reaction were of a simple one-hit nature, su...