Brief Communication: Detection of Mouse Mammary Tumor Virus in Cat Kidney Cells Infected With Purified B Particles From Rill Milk

Summary

A feline kidney cell line (CRFK-F2) was experimentally infected with B particles obtained by isopycnic banding of Rill milk on a Ficoll gradient. Free B particles were found in the culture supernatants 3 months post inoculation. Murine mammary tumor virus (MuMTV) antigen was then detected by membrane immunofluorescence; about 20% of the cells showed this specific antigen on their surfaces a year after infection. Electron microscopy revealed formation of virions in microvilli and accumulation of specific antibodies on their surfaces. Idiogram and zymogram studies confirmed that the cultivated cells were not of mouse origin. Active budding of MuMTV has not been detected in renewed attempts to infect these cells with Rill milk virus or an MuMTV from a BALB/cfC3H tumor celiline.