System for the Investigation of the Bacteriophage-directed Synthesis of Diphtherial Toxin

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Abstract
Lytic corynebacteriophage βhv64tox+has been characterized, and methods for studying the expression of its tox+gene in nontoxinogenicCorynebacterium diphtheriaestrain C7s(−)tox−described. During one cycle of viral growth there was a 1 million-fold increase in extracellular toxin. Both the conditions of the experiment and the use of purified phage, free from toxin, support the conclusion that all of the toxin was newly formed. This toxin was immunochemically indistinguishable from standard toxin produced by the PW8r(Pdi)tox+strain. Chloramphenicol was found to be an effective agent for synchronizing the initiation of viral growth. Once chloramphenicol was removed, intracellular toxin appeared and continued to increase throughout the latent period. Proflavine, added early in the latent period, blocked phage maturation without similarly affecting yields of toxin. Iron exerted a limited inhibitory effect on final toxin levels attained.