Salvador Luria

(1912 - 1991)

Salvador Edward Luria was born on August 13, 1912, in Torino, Italy. In 1935, Luria received his M.D. from the University of Torino. He fled to France in 1936 to escape from the fascist government of Benito Mussolini. From 1938 to 1940, he became a Research Fellow at the Institute of Radium in Paris. He later immigrated to the United States in 1940, to escape Nazi persecution.

After fleeing Europe, Luria was a Research Assistant in Surgical Bacteriology at Columbia University. From 1943 to 1950, he worked at Indiana University. In 1950, Luria was appointed by the University of Illinois as Professor of Microbiology.

A decade later, Luria moved to MIT, where he remained until retirement; from 1959-1964 he was the Professor of Microbiology; in 1964, he became the Sedgwick Professor of Biology; in 1970, he was appointed Institute Professor at the Department of Biology.

In the U.S., his work focused on the genetics of bacteriophages, viruses that infect bacteria. 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.

In January 1947, he became a naturalized citizen of the United States. Along with Max Delbrück and Alfred Hershey, Luria was awarded the 1969 Nobel Prize in Medicine. He was also a member of the National Academy of Sciences, American Academy of Arts and Sciences, American Society of Microbiology (President, 1967-1968).

Luria died in Lexington, Massachusetts on February 6, 1991.

The following press release from the Royal Swedish Academy of Sciences describes Luria’s work:

Around 1940, Delbrück, Hershey and Luria became interested in bacteriophage, a type of virus that infects bacteria, rather than ordinary cells. They were trying to find a living system as simple as possible, on which to study with hope of success, fundamental life processes, first of all self-replication. Bacteriophage soon revealed itself to be an object of choice for such research. They worked out rigorous quantitative methods and this turned bacteriophage research into an exact science. They synchronized virus multiplication and were thus able to follow in detail the various phases in the process. They studied what happened in single cells and analyzed their results with advanced statistical methods. They made a series of fundamental discoveries, of which the following will be mentioned.

As a result of infection, both virus and cell undergo drastic changes. The so-called cell-virus-complex behaves as an essentially new system. The chemical activities of the cell are reprogrammed. The virus loses its individuality and enters an "eclipse" or "dark" phase, during which it can no longer be identified as a particle. The metabolic activities which it releases can lead in a matter of minutes to the formation of hundreds of new virus particles.

The virus particle consists principally of nucleic acid surrounded by a protein shell. At infection the nucleic acid is injected by a simple but extremely efficient mechanism into the cell, while the protein shell remains outside. The role of nucleic acid as the carrier of the genetic information of the virus was thus demonstrated. The discovery of numerous genetic variants of the virus showed that the latter contained more than a single gene. Soon after genetic recombination was discovered to take place: two virus particles simultaneously infecting the same cell can exchange parts of their strings of genes and give origin to hybrid forms. This phenomenon made possible a detailed analysis of the genetic structure of the virus. Thanks to the short reproduction time of the virus and the large number of progeny virus obtained, bacteriophage work, in a matter of hours, can yield information that with other virus material might require months or years.

The work of Delbrück, Hershey and Luria has had a great impact on biology in general. Bacteriophages have served and continue to serve as models for the more complicated and less approachable systems represented by animal and human cells. Delbrück, Hershey and Luria have set the solid foundations on which modern molecular biology rests. Without their contributions the explosive development of this field would have been hardly possible. From the medical point of view, the discoveries for which the award is now given first of all imply a deeper insight into the nature of viruses and of virus diseases. Indirectly they also bring about an increased understanding of the mechanism of inheritance and of those mechanisms that control the development growth and function of tissues and organs. Over the years our debt of gratitude to the three leading figures of bacteriophage research has continually increased.

Sources: Wikipedia; Nobel Prize Biography; nobelprize.org