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Antiviral activity of phosphonoformate on rotavirus transcription and replication
Abstract:
The antiviral effect of foscarnet (PFA) on the replication of rotavirus, a member of the Reoviridae, was studied. The pyrophosphate analogue is an effective inhibitor of several viral polymerases acting on the enzyme pyrophosphate binding site. Replication of rotavirus in MA104 cells using different u.o.i. was inhibited by PFA in a concentration dependent manner, due to the inhibition of both plus- and minus-strand RNA synthesis. The addition of PFA to infected cells was specific for the inhibition of viral replication since uninfected cell incubated at the same PFA concentrations did not exhibit any cytotoxic effect. The 50% inhibitory effect of PFA on in vitro mRNA synthesis was obtained at a concentration of 150 microM. Over 80% of the in vitro minus-strand RNA synthesis was inhibited at a concentration of 320 microM, when PFA was assayed using replicase-enriched cell infected fraction. The results suggest that the effect may be due to an interaction of PFA with the viral polymerase, since this protein catalyses both plus- and minus-strand RNA synthesis. The results of experiments using the temperature-sensitive viral polymerase mutant show that the mutant is less sensitive to PFA, suggesting that this polypeptide is the target for PFA.
Insights
Foscarnet (PFA) effectively inhibits rotavirus replication by targeting the viral polymerase, impacting both RNA synthesis strands. This antiviral action is concentration-dependent and specific, showing no cytotoxicity in uninfected cells.
Area of Science:
- Virology
- Antiviral drug research
Background:
- Rotavirus, a Reoviridae family member, replicates within host cells.
- Viral polymerases are crucial for viral replication and are often targets for antiviral drugs.
- Foscarnet (PFA) is a pyrophosphate analogue known to inhibit viral polymerases.
Purpose of the Study:
- To investigate the antiviral effect of foscarnet (PFA) on rotavirus replication.
- To determine the mechanism of PFA's action against rotavirus.
Main Methods:
- Studied rotavirus replication in MA104 cells with varying multiplicities of infection.
- Assayed PFA's inhibitory effect on in vitro mRNA and minus-strand RNA synthesis.
- Utilized a temperature-sensitive viral polymerase mutant to identify the drug's target.
Main Results:
- PFA inhibited rotavirus replication in a concentration-dependent manner.
- PFA inhibited both plus- and minus-strand RNA synthesis.
- PFA demonstrated specific antiviral activity without causing cytotoxicity in uninfected cells.
- PFA showed significant inhibition of in vitro RNA synthesis, with 50% inhibition at 150 µM for mRNA and over 80% inhibition at 320 µM for minus-strand RNA synthesis.
- A temperature-sensitive viral polymerase mutant exhibited reduced sensitivity to PFA.
Conclusions:
- Foscarnet (PFA) effectively inhibits rotavirus replication.
- The antiviral effect is likely due to PFA's interaction with the viral polymerase.
- The viral polymerase is the probable molecular target of PFA in rotavirus.