Biophysical, biological, and cytochemical features of a virus associated with transplantable hamster tumors

A virus resembling type C murine leukemia viruses, which is associated with transplantable hamster tumors, was partially characterized with respect to certain biological, biophysical, and cytochemical features. As determined by electron microscopy, high concentrations of the virus appeared in the blood plasmas of tumor-bearing hamsters. Hamsters inoculated with virus concentrates did not show gross evidence of disease, and preliminary attempts to infect various hamster cells in tissue culture were unsuccessful. A line of cells from a virus-containing tumor which had been established in tissue culture released large numbers of the virus into the supernatant fluids by budding. The buoyant density peak of virus concentrates in potassium tartrate density gradients was 1.13 g/cm(3) by ultraviolet absorption and electron microscopic analysis. Acridine orange staining and nuclease digestion methods have indicated that the virus is probably a ribonucleic acid virus.