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Protein synthesis and membrane integrity in interferon-treated HeLa cells infected with encephalomyocarditis virus
Abstract:
The survival of interferon (IFN)-treated cells after encephalomyocarditis (EMC) virus infection depends on both the concentration of interferon and the multiplicity of infection (m.o.i.) used. The cell survived EMC infection if a high IFN/m.o.i. ratio was used in the experiment, whereas cell death took place at low IFN/m.o.i. ratios, even if IFN is also present during infection. Analysis by polyacrylamide gel electrophoresis of the proteins synthesized in IFN-treated cells subsequently infected with EMC indicated that no virus proteins were detected at either low or high multiplicities of infection. However, at low m.o.i. the cell survived and continued synthesizing cellular proteins exclusively, whereas at high m.o.i. a drastic shut-off of host protein synthesis took place. Virus which had been inactivated by u.v. irradiation was unable to cause the shut-off of host protein synthesis, either in control or in IFN-treated cells. This result suggests that some virus gene expression occurs in cells treated with IFN, although no virus protein synthesis was detected. The synthesis of virus RNA was also strongly inhibited after treated of cells with IFN. The integrity of the cell membrane in control and in IFN-treated cells was studied by analysing the 86Rb+ ion leakage, the thymidine pool, the chronic uptake and the entry of the translation inhibitor hygromycin B, to which cells are impermeable, at different times after EMC infection. The results obtained indicate that the early membrane leakiness observed after virus infection is not prevented by IFN treatment. However, the development of late leakiness to 86Rb+ ions, thymidine and hygromycin B was not observed in IFN-treated cells.
Insights
Interferon (IFN) treatment protects cells from encephalomyocarditis virus (EMC) infection, but survival depends on the IFN to virus ratio. High ratios prevent host shutoff and late membrane damage, ensuring cell survival.
Area of Science:
- Virology
- Cell Biology
- Immunology
Background:
- Interferon (IFN) is crucial for antiviral defense.
- Encephalomyocarditis virus (EMC) infection can lead to cell death.
- The interplay between IFN, EMC infection, and cell survival is complex.
Purpose of the Study:
- To investigate how interferon concentration and multiplicity of infection (m.o.i.) affect cell survival after EMC virus infection.
- To analyze the impact of IFN and EMC on host and viral protein synthesis.
- To assess the integrity of cell membranes in IFN-treated cells during EMC infection.
Main Methods:
- Cells were treated with varying concentrations of interferon (IFN) and infected with encephalomyocarditis virus (EMC) at different multiplicities of infection (m.o.i.).
- Protein synthesis was analyzed using polyacrylamide gel electrophoresis.
- Cell membrane integrity was assessed by measuring 86Rb+ ion leakage, thymidine pool, and hygromycin B uptake.
Main Results:
- Cell survival after EMC infection was dependent on a high IFN/m.o.i. ratio.
- No viral proteins were detected, but high m.o.i. led to host protein synthesis shut-off in untreated cells.
- IFN treatment prevented late-stage membrane leakiness, although early leakiness persisted.
Conclusions:
- A high IFN/m.o.i. ratio is critical for cell survival during EMC infection.
- IFN treatment inhibits viral RNA synthesis and prevents host shut-off and late membrane damage, suggesting partial viral gene expression.
- IFN confers protection by maintaining cell membrane integrity against late-stage viral damage.