Peyton Rous

In 1911, Peyton Rous discovered that a filterable agent—later named the Rous sarcoma virus (RSV)—could transmit cancerous tumors when transferred from a sick chicken to a healthy one. This was the first demonstration that a virus could cause cancer, a concept so far ahead of its time that it was largely dismissed for decades.

Rous's 1911 finding was met with deep skepticism because the idea that cancer could be caused by an infectious, filterable agent contradicted the prevailing understanding of tumors. It was only after the discovery of more cancer-causing viruses (oncogenic viruses) in the 1950s and 1960s—and the later identification of viral oncogenes—that the significance of Rous's work was fully appreciated, and he was awarded the Nobel Prize at the age of 87.

The Rous sarcoma virus carries a gene called v-src (viral src), which is responsible for its ability to transform infected cells into cancer cells. Later research showed that v-src originated from a normal cellular gene (c-src) that the virus had picked up—key evidence that normal cells contain genes that, when altered, can cause cancer, a foundational concept in modern oncology.

Rous spent essentially his entire career at the Rockefeller Institute for Medical Research (now Rockefeller University) in New York City. He made his chicken tumor virus discovery there in 1911, working with a Plymouth Rock hen that had been brought to the institute with a large tumor.