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pH 2 instability of a mutant of mengovirus is related to its interferon sensitivity
E A Bakich1, S J Monahan, E H Simon
1Department of Biochemistry and Biophysics, Texas A & M University, College Station.
Abstract:
The is-1 mutant of mengovirus is 100 times more sensitive to interferon (IFN) than wild type, as measured by a yield reduction assay in the G3 line of mouse L cells, and is also much more readily inactivated at pH 2. Neither isolated nor encapsidated RNA is degraded under these conditions, which suggests that the pH-sensitive region resides on the virus coat. One-third of the viruses selected for resistance to low pH also showed enhanced resistance to IFN. Attempts to isolate IFN resistant strains directly from is-1 stocks were unsuccessful. These results suggest that either a capsid protein or its precursor is an active anti-IFN agent.
Insights
Mengovirus is-1 mutants are highly sensitive to interferon (IFN) and low pH. Resistance to low pH correlated with IFN resistance, suggesting a viral coat protein acts as an anti-IFN agent.
Area of Science:
- Virology
- Immunology
- Molecular Biology
Background:
- Mengovirus is-1 mutant exhibits heightened sensitivity to interferon (IFN) compared to wild-type strains.
- This mutant is also more susceptible to inactivation at low pH (pH 2).
Purpose of the Study:
- To investigate the relationship between low pH sensitivity and IFN sensitivity in mengovirus.
- To identify the viral component responsible for IFN antagonism.
Main Methods:
- Yield reduction assays in mouse L cells to measure IFN sensitivity.
- Low pH inactivation experiments to assess viral stability.
- Selection of low pH-resistant mutants and subsequent IFN sensitivity testing.
Main Results:
- The is-1 mutant was 100-fold more sensitive to IFN than wild-type mengovirus.
- Low pH treatment inactivated the is-1 mutant more readily, with no RNA degradation observed.
- A subset of viruses selected for low pH resistance also displayed enhanced IFN resistance.
- Direct isolation of IFN-resistant strains from is-1 stocks was not achieved.
Conclusions:
- The viral capsid protein or its precursor is implicated as an active anti-IFN agent.
- The pH-sensitive region of the virus is likely located on the viral coat.
- A correlation exists between viral coat stability and IFN resistance.