Luria was born in Torino, Italy, but fled to France in 1936 and then to the United States in 1940 as his leftist, pacifist views were incongruent with the fascist regime of Italian dictator Benito Mussolini. In the US, his work focussed on the genetics of bacteriophages, viruses that infect bacteria. One of his early graduate students was James Watson, who went on to discover the structure of DNA with Francis Crick.
His famous experiment with Max Delbrück in 1943 demonstrated statistically that inheritance in bacteria must follow Darwinian rather than Larmarckian principles and that mutant bacteria occurring randomly can still bestow viral resistance without the virus being present. The idea that natural selection affects bacteria has profound consequences, for example, it explains how bacteria develop antibiotic resistance.