Abstract
Phagolessin A58, an antibiotic substance active against a number of bacterial viruses, was studied for activity against the seven T phages. Only three of the seven phages-T1, T3, and T7-proved to be sensitive to the antibiotic. The antibiotic caused a direct, apparently irreversible inactivation of free phage particles. A study of the properties of the inactivated phage particles showed that the particles retained the ability to kill host cells and to exert mutual exclusion against an unrelated phage after infectivity was lost. There was a progressive loss in these two properties when higher concentrations of antibiotic were used to inactivate the phage. Results with inactivated T3 and T7 revealed that these two properties-the ability to kill host cells and to exclude an unrelated phage-were lost at a different rate. They were, therefore, presumed to be different properties of these particular phage particles. The inactivation of phage by phagolessin A58 was inhibited by desoxyribose nucleic acid and to a lesser extent by ribose nucleic add. Cytosine, thymine, adenine, guanine, and cysteine failed to inhibit the reaction.