Abstract
The virogenic sarcoma RSL was induced in inbred Lewis rats by the Schmidt‐Ruppin variant of Rous virus (SR‐RSV).
Heterotransplantation of RSL cells to newborn C57BL/10Sn mice gave rise to mouse sarcomas in approximately 10% of the recipients. The properties of one of these mouse sarcomas, designated as RSM, were compared with those of the original rat tumour line RSL.
It was found that (1) RSL cells did not contain detectable amounts of infectious chicken, rat or mouse sarcoma virus. However, in contact with permissive chicken fibroblasts the RSL cells produced malignant conversion of avian cells accompanied by the formation of infectious RSV. RSL cells carried a tumour‐associated transplantation antigen (TATA) of Rous sarcomas, a group‐specific (gs) antigen of avian leukoviruses and a membrane antigen (MA), characteristic of Rous sarcomas, detectable by indirect immunofluorescence and cross‐reacting with MA of mouse Rous sarcomas. The MA characteristic of tumours induced by mouse leukoviruses was not detected in the membrane of RSL cells.
(2) RSM cells did not contain detectable amounts of oncogenic avian, mouse or rat viruses in an infectious form. Neither contact of these cells with permissive chicken c/o fibroblasts nor heterotransplantation of RSM tumours to chickens led to malignant conversion of avian cells. Gs antigen of avian leukoviruses was not detectable in RSM cells. However, TATA and MA characteristic of Rous sarcomas were present. Neither MA nor TATA induced by mouse leukoviruses was detected in RSM cells.
The results obtained indicate that the non‐infectious RSV genome present in rat virogenic cells is able to induce tumours in a further mammalian species.