Shope papilloma virus

Density-gradient separations of cytoplasmic fractions from liver have been carried out to study the distribution of activity of several enzymes (Thomson, 1959). Ribosomes and polysomes have been fractionated to elucidate the mechanisms of protein synthesis (Watson, 1964), Various viruses have been studied with the density-gradient technique polio virus (Levintow and Darnell, 1960), Rous sarcoma virus (Crawford, 1960), Shope papilloma virus (Williams et ai, 1960), and adenoviruses (Allison et ai, 1960). Density-gradient fractionation has been particularly useful for separation of DNA molecules from various species of bacteria (Rolfe and Meselson, 1959) and from animal cells (Kit, 1961), Other types of molecules, e.g., antibodies, lipoproteins, and rheumatoid factor have been isolated by density-gradient methods [see Charlwood (1966) for examples]. 

Ito, Y. and C.A. Evans. 1961. Induction of tumors in domestic rabbits with nucleic acid preparations from partially purified Shope papilloma virus and from extracts of the papilloma of domestic and cottontail rabbits. J. Exper. Med. 114 485-500. 

The first virus linked to tumor production was discovered in 1908 by Ellerman and Bang. Their finding was followed in 1911 by the better known discovery by Peyton Rous of a virus that produces sarcomas in chickens (now known as Rous sarcoma virus, or RSV). Later (1932) Shope showed that a papilloma virus produced cutaneous tumors in rabbits, and Lucke (1934) showed that adenoviruses produced renal adenocarcinoma in the frog. These and other discoveries made in the 1940s and 1950s indicated that exposure to certain viruses could result in tumor production. However, viral oncogenes had not yet been identified, and skeptics... 

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