Simultaneous production of mouse endogenous virus and Rous sarcoma virus by Schmidt-Ruppin virus infected mouse cells

Schmidt-Ruppin Rous sarcoma virus infected chick cells injected into newborn C₃H/f mice gave rise to tumours at the site of inoculation. These tumours were transplantable in adult C₃H/f mice and were able to induce tumours in the wing of adult Leghorn chickens. Tumour cells from the 18th passage in mice were used to establish a cell line in tissue culture (C₃HSR). These cells released C-type virus particles that produced foci and were able to propagate in chick cells. Cloning of the C₃HSR cells demonstrated that the same cell expressed both avian and murine antigens. Mouse cells infected with virus released by C₃HSR cells produced murine leukemia virus-like particles as revealed by the reverse XC syncytial test and by immunofluorescence tests.