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A Protocol for Analyzing Hepatitis C Virus Replication
Published on: June 26, 2014
Synergistic lethal mutagenesis of hepatitis C virus
Isabel Gallego1,2, María Eugenia Soria1, Josep Gregori2,3,4
1Centro de Biología Molecular "Severo Ochoa" (CSIC-UAM), Consejo Superior de Investigaciones Científicas (CSIC), Campus de Cantoblanco, 28049, Madrid, Spain.
Abstract:
Lethal mutagenesis is an antiviral approach that consists in extinguishing a virus by an excess of mutations acquired during replication in the presence of a mutagenic agent, often a nucleotide analogue. One of its advantages is its broad spectrum nature that renders the strategy potentially effective against emergent RNA viral infections. Here we describe synergistic lethal mutagenesis of hepatitis C virus (HCV) by a combination of favipiravir (T-705) and ribavirin. Synergy has been documented over a broad range of analogue concentrations using the Chou-Talalay method as implemented in the CompuSyn graphics, with average dose reduction index (DRI) above 1 (68.02±101.6 for favipiravir, and 5.83±6.07 for ribavirin), and average combination indices (CI) below 1 (0.52±0.28). Furthermore, analogue concentrations that individually did not extinguish high fitness HCV in ten serial infections, when used in combination they extinguished high fitness HCV in one to two passages. Although both analogues display a preference for G→A and C→U transitions, deep sequencing analysis of mutant spectra indicated a different preference of the two analogues for the mutation sites, thus unveiling a new possible synergy mechanism in lethal mutagenesis. Prospects of synergy among mutagenic nucleotides as a strategy to confront emerging viral infections are discussed.
Insights
This study shows that combining favipiravir and ribavirin creates synergistic lethal mutagenesis, effectively eliminating high-fitness hepatitis C virus (HCV). This antiviral strategy offers a potent approach against emerging RNA viral infections.
Area of Science:
- Virology
- Antiviral drug development
- Molecular biology
Background:
- Lethal mutagenesis is an antiviral strategy using mutagens to induce excessive viral mutations.
- Nucleotide analogues like favipiravir and ribavirin are key mutagens.
- Emergent RNA viral infections necessitate broad-spectrum antiviral approaches.
Purpose of the Study:
- To investigate the synergistic lethal mutagenesis of hepatitis C virus (HCV) using a combination of favipiravir and ribavirin.
- To evaluate the efficacy of this combination therapy in eliminating high-fitness HCV strains.
- To explore potential mechanisms of synergy between favipiravir and ribavirin.
Main Methods:
- Synergistic antiviral activity was assessed using the Chou-Talalay method and CompuSyn software.
- High-fitness HCV strains were subjected to serial infections in the presence of analogue combinations.
- Deep sequencing was employed to analyze viral mutant spectra and identify mutation preferences.
Main Results:
- The combination of favipiravir and ribavirin demonstrated synergistic lethal mutagenesis against HCV, with Combination Index (CI) values below 1.
- Dose reduction indices (DRI) indicated significant reductions in required analogue concentrations for favipiravir and ribavirin.
- Individually ineffective analogue concentrations synergistically eradicated high-fitness HCV within one to two passages.
- Deep sequencing revealed distinct mutation site preferences for favipiravir and ribavirin, suggesting a novel synergy mechanism.
Conclusions:
- Combined favipiravir and ribavirin induce synergistic lethal mutagenesis, offering a potent antiviral strategy against HCV.
- This synergistic approach can rapidly eliminate high-fitness viral strains, highlighting its potential for emergent infections.
- Understanding the differential mutation site preferences may reveal new avenues for optimizing lethal mutagenesis therapies.
