Italian-born American biologist who (with Max Delbrück (Delbrück, Max) and Alfred Day Hershey (Hershey, A.D.)) won the Nobel Prize for Physiology or Medicine in 1969 for research on bacteriophages (bacteriophage), viruses that infect bacteria.

Luria graduated from the University of Turin in 1935 and became a radiology specialist. He fled Italy for France in 1938 and went to the United States in 1940 after learning the techniques of phage research at the Pasteur Institute in Paris. Soon after his arrival, he met Delbrück, through whom he became involved with the American Phage Group, an informal scientific organization devoted to solving the problems of viral self-replication. Working with a member of the group in 1942, Luria obtained one of the electron micrographs of phage particles, which confirmed earlier descriptions of them as consisting of a round head and a thin tail.

In 1943 Luria and Delbrück published a paper showing that, contrary to the current view, viruses undergo permanent changes in their hereditary material. That same year he and Delbrück devised the fluctuation test, which provided experimental evidence that phage-resistant bacteria were the result of spontaneous mutations rather than a direct response to changes in the environment. In 1945 Hershey and Luria demonstrated the existence not only of such bacterial mutants (mutation) but also of spontaneous phage mutants.

Luria became Sedgwick professor of biology at the Massachusetts Institute of Technology in 1964. In 1974 he became director of the Center for Cancer Research at MIT. He was an author of a college textbook, General Virology (1953), and a popular text for the general reader, Life: The Unfinished Experiment (1973).