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Alterations of a mouse mammary tumor virus glycoprotein with interferon treatment
Abstract:
The effects of exogenous mouse interferon on the MJY-alpha mammary tumor cell line chronically infected with mouse mammary tumor virus (MMTV) were examined. Interferon at concentrations of 25 to 2,000 IU/ml in culture medium did not alter the growth rate or morphology of the cell layers. Electron microscopic examination of interferon-treated cells indicated a decrease in the numbers of A-type and budding B-type particles of MMTV. However, the levels of extracellular MMTV virions in the culture supernatants were not significantly reduced. Profiles of MMTV glycoproteins and nonglycosylated polypeptides obtained by sodium dodecyl sulfate-polyacrylamide gel electrophoresis of virions purified from interferon-treated cultures revealed increases in the relative levels of the 60,000-dalton glycoprotein, gp60.
Insights
Mouse interferon treatment reduced MMTV particle production within cells but did not decrease extracellular virions. This suggests interferon affects MMTV replication, altering glycoprotein profiles in purified virions.
Area of Science:
- Virology
- Cell Biology
- Immunology
Background:
- Mouse mammary tumor virus (MMTV) is a retrovirus associated with mammary tumors in mice.
- Interferons are cytokines that modulate immune responses and have antiviral properties.
- MJY-alpha cells provide a model system for studying MMTV infection.
Purpose of the Study:
- To investigate the impact of exogenous mouse interferon on MMTV-infected MJY-alpha cells.
- To determine if interferon affects MMTV replication, particle assembly, or virion composition.
Main Methods:
- Treatment of MMTV-infected MJY-alpha cells with varying concentrations of mouse interferon.
- Assessment of cell growth and morphology.
- Electron microscopy to visualize MMTV particles (A-type and budding B-type).
- Analysis of extracellular virions in culture supernatants.
- Sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) to analyze MMTV virion protein profiles.
Main Results:
- Interferon did not alter the growth rate or morphology of MJY-alpha cells.
- Electron microscopy showed a reduction in intracellular A-type and budding B-type MMTV particles in interferon-treated cells.
- Extracellular MMTV virion levels in culture supernatants were not significantly reduced.
- SDS-PAGE analysis of purified virions revealed an increased relative level of the 60,000-dalton glycoprotein (gp60).
Conclusions:
- Exogenous mouse interferon inhibits intracellular MMTV particle formation in MJY-alpha cells.
- Interferon treatment leads to alterations in the glycoprotein composition of MMTV virions.
- The findings suggest a complex interaction between interferon and MMTV replication, affecting both particle assembly and virion structure.