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Synthesis and cleavage processing of oncornavirus proteins during interferon inhibition of virus particle release
Abstract:
The effect of interferon on the rate of synthesis and the cleavage processing of viral proteins in mouse cells, chronically infected with Rauscher murine leukemia virus, has been studied by immunoprecipitation of newly synthesized viral proteins from virus-infected cells pulse-labeled with [35S]methionine. Immuno-precipitated, labeled polypeptides were resolved by polyacrylamide gel electrophoresis in the presence of sodium dodecyl sulfate and then examined by autoradiography. Cleavage processing was studied in the same manner with cells that had been pulse-labeled and then incubated with non-radioactive media for a sufficient time to allow normal cleavage processing to occur. At a concentration that strongly inhibited the release of virus particles, interferon had no effect on the synthesis of proteins carrying antigenic determinants of the major core protein p30 or of the envelope glycoprotein gp69/71. Nor did it affect the post-translational cleavage processing of the precursors to these proteins. Similarly, interferon did not affect labeling or chasing of precursor protein carrying the p15 determinants; labeling of p15 itself could not be studied because it does not contain methionine.
Insights
Interferon treatment did not alter the synthesis or processing of key viral proteins in Rauscher murine leukemia virus-infected mouse cells. This antiviral protein did not impact major core or envelope glycoprotein production or their precursor cleavage.
Area of Science:
- Virology
- Immunology
- Molecular Biology
Background:
- Rauscher murine leukemia virus (RMLV) is a retrovirus that infects mouse cells.
- Interferon is a cytokine known to have antiviral properties.
- Understanding how interferon affects viral protein synthesis and processing is crucial for developing antiviral therapies.
Purpose of the Study:
- To investigate the effect of interferon on the synthesis and cleavage processing of viral proteins in RMLV-infected mouse cells.
- To determine if interferon influences the production of major core protein (p30) and envelope glycoprotein (gp69/71).
Main Methods:
- Cells chronically infected with RMLV were pulse-labeled with [35S]methionine.
- Newly synthesized viral proteins were immunoprecipitated and analyzed by SDS-PAGE and autoradiography.
- Post-translational cleavage processing was assessed by pulse-chase experiments.
Main Results:
- Interferon, at concentrations inhibiting virus release, did not affect the synthesis of p30 or gp69/71 viral proteins.
- Interferon also did not alter the post-translational cleavage processing of precursors for p30 and gp69/71.
- Labeling and chasing of the p15 precursor protein were also unaffected by interferon.
Conclusions:
- Interferon does not inhibit RMLV replication by affecting the synthesis or cleavage processing of major viral structural proteins.
- The antiviral mechanism of interferon in this model likely operates through pathways other than direct inhibition of viral protein synthesis or processing.