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 leukaemia virus-like particles as revealed by the reverse XC syncytial test and by immunofluorescence tests.