Studies on a transplantable murine rhabdomyosarcoma.

Well-differentiated rhabdomyosarcomas developed in 8 of 10 BALB/c mice inoculated with cell-free extracts of two lesions arising in bats previously inoculated with the Moloney strain of murine sarcoma virus. The tumors could be transplanted in BALB/c mice and other strains of mice compatible at the H-2 locus. A tumorigenic clonal cell culture line (R2) was established from a transplanted tumor. Ultrastructural studies of the primary and transplanted tumors and R2 cells revealed thick and thin myofilaments characteristic of myoblasts. These cells contained numerous cisternal type-A virus-like particles, but no type-C particles were found. Attempts to recover, rescue, or chemically induce transforming or nontransforming viruses from transplantable tumors and the R2 cell line were unsuccessful. The tumor cells lacked the murine type-C virus gs antigen. Hybridization data confirmed the apparent lack of viral RNA in the tumor cells.