Renato Dulbecco

Renato Dulbecco was an Italian-American virologist who developed the plaque assay, a quantitative technique for measuring the concentration of infectious animal viruses by counting the small clear zones, or plaques, that individual virus particles produce as they kill and spread through a layer of cultured cells. Adapting a method previously used for bacteriophage to animal viruses in the early 1950s, Dulbecco plaque assay gave virology a precise, reproducible way to measure virus concentration that had been lacking, and it became a standard technique across the field. Dulbecco went on to study how certain tumor viruses, later called oncoviruses, cause cancer by inserting their own genetic material into the chromosomes of the host cell, permanently altering the cell genetic program and driving it toward uncontrolled growth. He shared the 1975 Nobel Prize in Physiology or Medicine with two of his own former trainees, Howard Temin and David Baltimore, whose discovery of the enzyme reverse transcriptase built directly on techniques and questions Dulbecco had established in his own laboratory. He studied medicine at the University of Turin under Giuseppe Levi, later worked at Indiana University, the California Institute of Technology, the Salk Institute and the Imperial Cancer Research Fund in London, helped launch the Human Genome Project in 1986, and continued research on cancer stem cells until 2011.