A new papillomavirus associated with alimentary cancer in cattle

Abstract

A high incidence area of carcinoma of the alimentary tract of cattle has been reported^1–4. The carcinomas are preceded by papillomas which may transform to malignancy. A papillomavirus was isolated from these warts and was shown to occur as a widespread infection of cattle in the UK². In the high cancer area there is a marked increase in the overall incidence of this infection, an increase in the number of papillomas per animal and an increase in the number of specific sites of infection as compared with cattle from adjacent areas where cancers are not found. The papillomas are found in young animals but carcinomas do not develop until the cows are over 7yr old. There is strong circumstantial evidence¹ that the factor associated with the increased multiplicity of papillomas and the subsequent malignant transformation is the ingestion of bracken fern. This plant is known to possess radiomimetic, mutagenic and carcinogenic activity. Preliminary experimental evidence supports the circumstantial data and we also have preliminary evidence of the presence of viral genome sequences, without production of virus, in the cells of carcinomas. In addition to the alimentary papillomas of the type described above, three more major patterns of bovine papillomatosis are found in the UK⁵ — cutaneous fibropapillomatosis, papillomatosis of the skin of the udder and teats, and papilloma of the penis. We have extracted papillomaviruses from all the above tumours, and our results, published in a preliminary form elsewhere⁵, indicate that the different lesions are caused by different papillomaviruses. Here we report the partial characterization of the virus involved in alimentary tract tumours and its differentiation from other bovine papillomaviruses. The system seems to present a dis-sectable model for investigating the mechanistic relationship between the viral infection and the ingestion of an environmental ‘carcinogen’.