Studies of Hamster-Specific Oncogenic Virus Derived from Hamster Tumors Induced by Kirsten Murine Sarcoma Virus

Hamster tumors induced by the Kirsten strain of murine sarcoma virus (Ki-MSV) were found to contain a virus antigenically distinct from Ki-MSV. The virus had a restricted host-range and was infectious only for the hamster species but not for the mouse species from which the Ki-MSV was originally derived. The hamster-specific virus produced foci of cell transformation in hamster embryo fibroblasts and progressively growing sarcomas in newborn hamsters. One established tissue culture line of in vitro transformed hamster embryo cells (Line SLH) was found to release the hamster-specific focus-forming and sarcomagenic virus. These independent observations confirm and extend the recent observations of other investigators on the presence of such hamster-specific viruses in hamster tumors induced by various strains of murine sarcoma virus.