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Spontaneous appearance of cytopathology and rat C‐type virus (WF‐1) in a rat embryo cell line
Author(s) -
Bergs Victor V.,
Pearson Gary,
Chopra Harish C.,
Turner Willie
Publication year - 1972
Publication title -
international journal of cancer
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.475
H-Index - 234
eISSN - 1097-0215
pISSN - 0020-7136
DOI - 10.1002/ijc.2910100122
Subject(s) - virus , biology , cytopathology , embryo , cell culture , extracellular , budding , virology , microbiology and biotechnology , antigen , immunology , cytology , genetics
An established line (WF‐1) of Wistar/Furth rat embryo cells spontaneously developed cytopathology after about 2 years in vitro. The cellular changes appeared within 5–7 days after subculturing of the cultures and consisted of altered rounded and fusiform cells with dark, prominent nuclei. These changes increased after removal of bovine amniotic fluid from the culture nutrient but were not apparent if the cultures were subcultured at 3–4 day intervals. Most of the altered cells were viable, but they failed to multioly under the conditions employed. Electron microscopical examination of the WF‐1 cells revealed numerous extracellular and budding C‐type virus particles. The cells, when inoculated into rats, produced progressively growing fibrosarcomas which also contained C‐type particles. Initially the WF‐1 virus failed to produce visible effects in the REL line of Sprague‐Dawley rat embryo cells. Several months later, upon concentration and banding at 1.16 g/cm 3 in a sucrose gradient, low‐titered infectious virus of about I TCID 50 per 10,000 virus particles was recovered. This produced foci of predominantly viable rounded cells in REL cultures similar to those induced by the C‐type virus (RMTDV or BV‐1) previously isolated from chemically induced rat mammary tumors. Immune BV‐1 serum prevented the WF‐1 virus from producing these cellular effects. Tests for properties characteristic of murine leukemia viruses (gs‐1 antigen, gs‐3 interspecies antigen, and the XC reaction) were negative indicating that the WF‐1 virus was not a mouse virus. These observations suggested that upon prolonged cultivation in vitro the WF‐1 rat embryo cells spontaneously liberated a rat C‐type virus related to the BV‐1. Whether the cell‐altering and partially lethal effects produced by the WF‐1 virus were due to some cytopathic C‐type particles in a generally non‐cytopathic population or reflected the concentration of only one biological type of particles needs further study.