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Effect of human fibroblast interferon on uncoating and release of murine leukaemia virus in NIH/3T3 mouse cells
Abstract:
The effect of human fibroblast interferon (IFN), a heterologous IFN, on the uncoating of murine leukaemia virus (MLV) was investigated in exogenously infected NIH/3T3 mouse cells. Virus uncoating was determined by following the disappearance of the penetrating virus particles from the cytoplasm of the infected cells. Intracellular virus particles were estimated by sedimenting them at high speed from the cytoplasmic fraction of the infected cells and assaying their reverse transcriptase activity. In untreated control cells, uncoating started immediately after penetration, but in cells treated with human IFN, uncoating was delayed for 2 to 3 h. This delay led to prolongation of the infectious cycle, with delayed release of progeny virus. The delay in release did not result from inhibition by IFN of the process of release, since in NIH/3T3 cells chronically infected with MLV, treatment with IFN had no effect on virus release.
Insights
Human fibroblast interferon (IFN) delays murine leukemia virus (MLV) uncoating in mouse cells. This delay prolongs the viral infectious cycle but does not affect progeny virus release.
Area of Science:
- Virology
- Immunology
- Cell Biology
Background:
- Interferons (IFNs) are crucial antiviral proteins.
- Heterologous IFNs can modulate viral replication cycles.
- Understanding viral uncoating is key to antiviral strategies.
Purpose of the Study:
- To investigate the effect of human fibroblast interferon (IFN) on murine leukemia virus (MLV) uncoating.
- To determine if IFN influences the kinetics of viral uncoating and subsequent replication steps.
Main Methods:
- Exogenous infection of NIH/3T3 mouse cells with MLV.
- Monitoring virus uncoating by tracking penetrating virus particles in the cytoplasm.
- Quantifying intracellular MLV via reverse transcriptase activity assay.
Main Results:
- Virus uncoating initiated immediately post-penetration in control cells.
- Human IFN treatment delayed MLV uncoating by 2-3 hours.
- Delayed uncoating resulted in a prolonged infectious cycle and delayed progeny virus release.
Conclusions:
- Human fibroblast interferon (IFN) significantly delays murine leukemia virus (MLV) uncoating.
- The delay in uncoating, not release, impacts the viral infectious cycle.
- IFN's antiviral mechanism involves modulating early viral events like uncoating.
