Purnell Choppin, whose work was integral to understanding viral mechanics, died on July 3, just one day shy of his 92nd birthday, of prostate cancer. He was a founding member of the American Society for Virology and is best known for his time as president of the Howard Hughes Medical Institute (HHMI), which he shaped into one of the world’s largest scientific philanthropic organizations.

Choppin was born in Baton Rouge, Louisiana, in 1929. He stayed local for his education, graduating from Louisiana State University in 1949 and earning his medical degree there in 1953. The following year, he joined the United States Air Force and served as a medical officer. Bookending his service, he completed an internship and residency at hospitals in St. Louis, Missouri.

Switching from medical practice to research, Choppin joined the Rockefeller University in 1957 as a postdoc. According to the university’s obituary, Choppin used his own throat as a source of the H2N2 influenza virus that winter, a sample that went on to be used widely in research. In 1959, he became a professor at the school and eventually headed up the virology department. While at Rockefeller, he studied how the spike proteins on viruses infect cells and lead to replication.

After many years of discussions about the need for a focused association for researchers who studied viruses, in 1981 Choppin was invited to join the inaugural meeting of what would become the American Society for Virologists. Choppin would later serve as the society’s fourth president, from 1985–1986.

In 1985, Choppin left Rockefeller to become the chief scientific officer and vice president at HHMI. Two years later, he became president of the institute. According to HHMI, when Choppin came in, there were 96 researchers working with an annual budget of $77 million. By the time he retired in 1999, HHMI had grown into one of the largest science philanthropies in the world, with a team of 330 researchers and a $556 million annual budget.

It wasn’t just the numbers that grew, but the number of places where HHMI researchers worked. During Chopin’s tenure, HHMI established labs at more than 70 universities. This allowed the organization to more readily onboard talented scientists who might have been reluctant to relocate to the main facility in Chevy Chase, Maryland.

“It really was very exciting to suddenly have the resources to support the best people we could find, wherever they were,” Choppin told HHMI in 2013. “We don’t have to uproot people. I mean the amount of investment we can make, the fact that we can support people wherever they are . . . that’s unusual.”

After his retirement from HHMI, he joined the board of the Lasker Foundation, an organization that champions public funding for medical research, serving until 2011.

Choppin is survived by his wife of 62 years, Joan, and their daughter Kathleen. A service for him will be held at Arlington National Cemetery.