In a career spanning seven decades, Dr. Dulbecco was a medical officer in the Italian army during World War II and then served with anti-German partisan forces. Focusing on scientific research after the war, he contributed to seminal advances in virology that culminated in his Nobel Prize.

One of Dr. Dulbecco’s most celebrated post-Nobel contributions was a paper he wrote for the journal Science in 1986 that advocated the complete sequencing of the human genome.

It was a bold idea at a time when many scientists were content to look at the specific genes related to their subfields. But Dr. Dulbecco foresaw the need to unravel the human genome as a prerequisite to understanding the nature of cancer.

His paper was credited with helping spark the federally funded Human Genome Project, which began in 1990 under his former colleague, James Watson, and was completed in 2003.

As a young scientist at the California Institute of Technology, Dr. Dulbecco set the groundwork for his later research by developing the innovative “plaque technique” to see viruses in action at the cellular level.

The technique allowed researchers to look at a culture sample and count the plaques, or clear spots, showing where the viruses had killed the host cells. This work — done in collaboration with biologist Marguerite Vogt — was widely credited with helping transform animal virology from a descriptive to a quantitative science.

In trying to understand the forces by which viruses infect cells and then propagate, Dr. Dulbecco built on seminal work in the early 20th century by Peyton Rous and other top scientists.

Starting at Caltech and later at the Salk Institute, Dr. Dulbecco worked with mouse cells to investigate the methods by which tumor viruses invade normal cells and seize control of their genetic structure.

His studies on mice explored two key phases of the virus’s life cycle. He showed how the genetic material of the polyoma virus can make more copies of itself and ultimately kill the cell or, more treacherously, become a stable part of that cell and cause it to proliferate, ultimately forming a tumor.

Tony Hunter, a molecular and cell biologist who now directs the Salk Institute Cancer Center, said Dr. Dulbecco made significant discoveries in the early days of tumor virology.

Previously, Hunter said, scientists viewed the interaction of a tumor virus and cell like a “hit-and-run” accident in which the effect was clear but the causes were not.

Dr. Dulbecco’s research “provided genetic evidence that the virus became part of the genome in the cancer cell,” Hunter said.