Renato Dulbecco

Renato Dulbecco, born in 1914, Italian-born American virologist and cowinner of the 1975 Nobel Prize in physiology or medicine, which he shared with American molecular biologist David Baltimore and American virologist Howard M. Temin for discoveries concerning the action of tumor viruses on the genetic structure of the cells they infect.

Dulbecco was born in Catanzaro, Italy, on February 22, 1914. He earned a medical degree in 1936 from the University of Turin, where microbiologist Salvador Luria was a fellow student. From 1936 to 1938 Dulbecco served as a physician in the Italian Army. Although he was discharged in 1938, he was recalled in 1939 to fight in France and also in Russia during World War II (1939-1945). After the war, he was named an assistant professor of embryology at the University of Turin. In 1947 Dulbecco accepted Luria's invitation to come to Indiana University in Bloomington. In 1949 he moved to the California Institute of Technology (Caltech), where he worked with biologist Max Delbrück. Dulbecco was named an associate professor of biology at Caltech in 1952, and a full professor in 1954. When the Salk Institute for Biological Studies was founded in 1963, Dulbecco became one of its first research fellows. In 1972 he joined the Imperial Cancer Research Fund Laboratories in London, England, where he eventually became deputy director. He returned to the Salk Institute in 1977 as a distinguished professor, a position from which he retired in 1992.

In the late 1940s and early 1950s Dulbecco worked with Salvador Luria on the genetics of bacteriophage, a virus that infects bacteria and causes changes in its genetic structure. By the mid-1950s Dulbecco, then working with Max Delbrück, began to study tumor viruses, whose mechanism of action is similar to that of bacteriophage. Like bacteriophage, a ribonucleic acid (RNA) tumor virus imposes its own genetic instructions on the deoxyribonucleic acid (DNA) of the cell it infects. Dulbecco described this process, called cell transformation, in detail. The protein coat of the invading virus carries an enzyme (later identified by Temin and Baltimore as reverse transcriptase) that changes the DNA of the infected cell. This type of virus, called a retrovirus, causes hepatitis, acquired immunodeficiency syndrome (AIDS), and some types of cancer. A retrovirus causes cancer by destroying the regulatory mechanism of the cell. Normal cells can monitor their own growth relative to other cells and halt replication when a cell meets its neighbors. But the retrovirus destroys this mechanism, and runaway growth is the result. Dulbecco also invented the plaque-assay method for determining the amount of virus in a cell culture, a useful technique that hastened the development of the Sabin polio vaccine.