Peyton Rous discovered the viral etiology of a chicken sarcoma in 1911 through his interest in tumor transplant ability to new hosts by a filtrate. He commented: "The behaviour of thenew growth has been throughout that of a true neoplasm, for which reason the fact of its transmission by means of a cell-free nitrate assumes exceptional importance" (1911).
In 1966 he was awarded a Nobel Prize in Physiology or Medicine for work he carried out on chickens in 1911, that gave the first experimental proof of a virus causing cancer.