Research that could have led them in the right direction was done in the 1930’s by Dr. Richard Shope of the Rockefeller University, who on a hunting trip heard a friend describe seeing rabbits with “horns,” which were actually large warts.
Dr. Shope asked his friend to send some of the horns. He then ground them up, filtered them through porcelain that let only tiny virus-size particles through, and injected the filtrate into other rabbits, which grew horns in turn.
“Incidentally, that’s where the jackalope myth comes from,” said Dr. William Bonnez, who was part of the University of Rochester’s vaccine development team. (Jackalopes, jackrabbits with antelope horns, are made by taxidermists and appear on things like postcards from Wyoming. But references to horned rabbits go back centuries, and their condition probably stemmed from papilloma infections.)
Dr. Shopeâ€™s work showed the cause was a virus, but it was not until the 1980â€™s that DNA amplification allowed a German researcher, Dr. Harald zur Hausen, to pin down papilloma as the cause.
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