Rous at microscope in laboratory. No location or date given. Francis Peyton Rous (1879-1970) was an American virologist who received his B.A. and M.D. from Johns Hopkins University. In 1911, he observed that a malignant tumor (a sarcoma) growing on a domestic chicken could be transferred to another fowl simply by exposing the healthy bird to a cell-free filtrate. That cancer could be transmitted by a virus (Rous sarcoma virus, a retrovirus), was widely discredited by experts at that time. It was several years before anyone even tried to replicate his prescient results. In 1966, over 50 years after his seminal observation, he was awarded a Nobel Prize in Physiology or Medicine for his work. He died in 1970 at the age of 90.