In 1933 Shope described an infectious papilloma of wild cattontail rabbits. Shope rabbit papilloma is a virus-induced epidermal neopIasm indigenous to western cottontail rabbits and readily transmissible to domestic rabbits by inocuiation with an cell-free extract of wild cottontail papilloma. Shope papilloma induced in the domestic rabbits may spoataneously, remain benign, or progress to carcinoma. Kidd et al. (1936) noted that the regression is not correlated with the titer of virus neutralizing antibody. The possibility that papilloma regression is brought about by a mechanism anaIogous to that operating in allograft rejection was suggested by kidd et al. (1938) with the view of the histological resemblance between papilloma regression and rejection of allografted tissue. That regression is mediated by an immune mechanism is strongly indicated by the findings of Evans et al.(1962) that the proportion of rabbits showing regression is substantially increased by vaccination of rabbits with their own papilloma tissue or with papilloma tissue from another rabbits. McMichael (1967) demonstrated that suppression of regression was achieved by use of large doses of corticosteroid. The effect of 5-fluorouracil on human warts was mentioned as being effective by Goldman et al. (1963). In Korea resinous extract from Paulownia coreana has long been used empirically in the treatment of human warts. In this investigation effects of dexamethasone administration on the development and the spontaneous regression of Shope papillomas in domestic rabbits were studied. At the same time, observations were made to evaluate the comparative effectiveness of topical application of 5% 5-fluorouracil ointment and resinous extract from Paulownia coreana on Shope papilloma in the domestic rabbit. The results are summarized as follows: l. Administration of dexamethasone significantly reduced the spontaneous regression of Shope papillomas in domestic rabbits by 12 weeks after virus inoculation. 2. Topical application of 5% 5-fluorouracil ointment on Shope papillomas cured the tumors by 4 weeks of drug application. However, similar treament with resinous extract from Paulownia coreana was without any demonstrable effects. 3. Marked losses of body weights became manifest in dexamethasone treated rabbits. 4. Reinoculation of Shope papilloma virus into 2 rabbits whose papillomas had regressed 3 months ago failed to produce papillomas.
Allografts ; Antibodies, Neutralizing ; Body Weight ; Cottontail rabbit papillomavirus ; Dexamethasone* ; Fluorouracil ; Humans ; Korea ; Papilloma* ; Rabbits ; Tumor Virus Infections ; Vaccination ; Warts