A NONHEREDITARY, HOST-INDUCED VARIATION OF BACTERIAL VIRUSES

In this article, Luria reported that some bacteria, when infected with phage, would modify the phage in such a way so that it cannot reproduce in that particular bacteria type. However, the variation gives the phage the ability to infect a different bacterial species, in this instance Shigella. This is the first instance of the phenomenon of restriction and modification that would soon after be explained by the discovery of restriction enzymes in bacteria. Luria's work with Human, which described bacterial restriction-modification systems, eventually led to the discovery of restriction enzymes.