Papillomaviruses were first identified in the early 20th century, when it was shown that skin
warts, or
papillomas, could be transmitted between individuals by a filterable infectious agent. In 1935
Francis Peyton Rous, who had previously demonstrated the existence of a cancer-causing
sarcoma virus in chickens, went on to show that a papillomavirus could cause skin cancer in infected rabbits. This was the first demonstration that a virus could cause cancer in mammals.
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