Integrated shope virus DNA is present and transcribed in the transplantable rabbit tumour Vx-7

To facilitate a molecular analysis of Shope papilloma virus-induced neoplastic cells, we have established a cell line from Vx-7, a transplantable tumour originally induced by the Shope virus. Single phase molecular hybridization and Southern transfer methods were employed to assess copy number and physical state of the DNA, and the extent of transcription. Both tumour and cell line were found to contain multiple copies of the virus genome and these were all integrated into the host cell DNA. Transcripts corresponding to a complexity of approx. 1% of the virus genome were detected at low abundance. These results are discussed relative to our earlier findings with tumours induced directly by virus, and to requirements for maintenance of the Vx-7 tumour over the 30 years that it has been in existence.