Salvador Edward Luria

Luria, Salvador Edward (1912-1991), an Italian-born American biologist, shared the 1969 Nobel Prize in physiology or medicine with German-born American biophysicist Max Delbrück and American biologist Alfred D. Hershey for their work with bacteriophages (viruses that attack bacteria). The work of Luria, Delbrück, and Hershey led other scientists to discover the structure and importance of DNA (deoxyribonucleic acid).

Luria was born Aug. 13, 1912, in Turin, Italy, to David and Ester Sacerdote Luria. In 1929, Luria began studying medicine at the University of Turin. Working with a renowned professor of anatomy and histology, he learned how to culture living cells. He earned his medical degree with summa cum laude honors at Turin in 1935. He then served three years as a medical officer in the Italian army.


As Italy's fascist government allied itself with Germany and led the nation into World War II (1939–1945), Luria, who was of Jewish descent, left Italy to be safe. From 1938 to 1940, he studied medical physics and radiology at the Curie Laboratory of the Institute of Radium in Paris. He developed an interest in bacteriophages and became involved with experiments applying irradiation to bacteriophage particles in an attempt to produce genetic mutations. A genetic mutation is a change in the hereditary material of an organism's cells. Hereditary material consists of genes and chromosomes.

In 1940, Luria went to the United States to accept an appointment as a research assistant at the College of Physicians and Surgeons of Columbia University in New York City. Around 1941, he met Max Delbriick at a meeting of the American Physical Society in Philadelphia. Delbriick later spent a few days in Luria's laboratory in New York, and the two scientists planned a series of experiments. A 1942–1943 Guggenheim Fellowship allowed Luria to work at Princeton University, New Jersey, and at Vanderbilt University, in Nashville, Tennessee, with Delbrück.

From 1943 to 1950, Luria was an instructor, assistant professor, and associate professor of bacteriology at Indiana University in Bloomington. In 1950, he became professor of microbiology at the University of Illinois in Urbana.

In the early 1940's, scientists knew little about the nature of viruses, microscopic organisms that are a major cause of disease. Delbrück, Luria, and Alfred Hershey, who was associated with Washington University School of Medicine, in St. Louis, Missouri, each performed research on bacteriophages, viruses that attack bacteria. The word bacteriophage means bacteria eater. Bacteria have tough cell walls. To penetrate these walls, some bacteriophages have a structure that works like a hypodermic needle. This structure consists of a sphere-shaped head that contains a nucleic acid, and a hollow, rod-shaped tail made of protein. When a bacteriophage enters a bacterium, the tail first penetrates the cell wall. Then the nucleic acid in the head moves through the tail and into the cell.

During 10 years of study together, Luria, Delbrück, and Hershey were instrumental in advancing knowledge about phages. In 1951, Luria showed that when bacteriophages grow, clones of phage mutants arise by random spontaneous mutations. Luria published proof that bacteriophage genes and genes of other viruses, undergo spontaneous mutations in a process similar to that of bacteria.

In 1952, Hershey and his assistant, Martha Chase, investigated what happens when bacteriophages attack. They found that the phages affect the DNA of the bacteria. DNA is the substance that makes up genes, the material in cells that determines the characteristics of an organism. Hershey and Chase proved that when the phage invades a cell, the phage's DNA sheds its protein coating and takes over the genetic mechanism of the bacteria, forcing it to reproduce new viruses instead of new bacteria. This opened the door to numerous discoveries of how more complex organisms reproduce and pass on hereditary characteristics.

Luria had planned to present his paper on spontaneous mutation in bacteriophages at the 1953 meeting of the Society for General Microbiology in Oxford, England. However, due to an American political climate of alarm about possible Communist activity, the government denied Luria a visa for travel. His former student James Dewey Watson read Luria's paper, which contended that the phage protein, rather than its DNA, carried the genetic information.

Luria became professor of microbiology at the Massachusetts Institute of Technology (MIT), in Cambridge, Massachusetts, in 1959. At MIT, he developed a training program for young scientists in bacterial and viral genetics. He also studied the biochemistry of bacterial cell membranes. In 1964, he became professor of biology at MIT. In 1965, he also became a nonresident fellow of the Salk Institute for Biological Studies in San Diego, California. Luria founded and became director of MIT's Center for Cancer Research in 1974.

Luria also earned notoriety for his ideas on several social and political issues. He criticized the development of biological weaponry and what he considered the excessive spending of the United States on its lunar exploration program. He also opposed American involvement in the Vietnam War (1957–1975), which escalated in the 1960's. He spoke against Israel's invasion of Lebanon and the lack of safeguards in the nuclear power industry. He believed that more money needed to be devoted to medical research and housing for disadvantaged people. Luria donated a large portion of his Nobel Prize money to several antiwar groups. As a result of his activism, the U.S. Health, Education, and Welfare Department blacklisted Luria from serving on any of its advisory panels. The blacklist was reportedly ended about 1970.

When the three researchers were awarded the Nobel Prize in physiology or medicine in 1969 for their discoveries concerning the replication mechanism and the genetic structure of viruses, Delbrück was associated with the California Institute of Technology, in Pasadena, California, and Hershey was with the Carnegie Institution, Washington, D.C.

Luria received numerous other awards, and also served as editor or editorial board member of a number of medical and science journals. He wrote many articles for such journals as well as General Virology, first published in 1953, which became a standard textbook. In 1974, he won the National Book Award in the sciences category for Life: The Unfinished Experiment. Luria was also a member of a number of professional societies.

The pioneering work of Luria, Delbrück, and Hershey contributed immensely to the field of medicine, especially in fighting viral diseases. Their work also boosted the field of genetics. In 1953, James Dewey Watson and Francis H. C. Crick identified the structure of the DNA molecule as a spiral form called a double helix. That achievement allowed scientists to understand the hereditary process in chemical terms. In 1969, Jonathan Beckwith and his associates at Harvard University succeeded in isolating a single gene.