Hepatitis C Virus Resistance to Carbohydrate-Binding Agents

Laure Izquierdo,Virginie Morel,Etienne Brochot,Sandrine Castelain,Carole Fournier,Véronique Descamps,Catarina Oliveira,Gilles Duverlie,Jean Dubuisson,Francois Helle,Catherine Francois

doi:10.1371/journal.pone.0149064

Abstract

Carbohydrate binding agents (CBAs), including natural lectins, are more and more considered as broad-spectrum antivirals. These molecules are able to directly inhibit many viruses such as Human Immunodeficiency Virus (HIV), Hepatitis C Virus (HCV), Dengue Virus, Ebola Virus or Severe Acute Respiratory Syndrome Coronavirus through binding to envelope protein N-glycans. In the case of HIV, it has been shown that CBAs select for mutant viruses with N-glycosylation site deletions which are more sensitive to neutralizing antibodies. In this study we aimed at evaluating the HCV resistance to CBAs in vitro. HCV was cultivated in the presence of increasing Galanthus nivalis agglutinin (GNA), Cyanovirin-N, Concanavalin-A or Griffithsin concentrations, during more than eight weeks. At the end of lectin exposure, the genome of the isolated strains was sequenced and several potential resistance mutations in the E1E2 envelope glycoproteins were identified. The effect of these mutations on viral fitness as well as on sensitivity to inhibition by lectins, soluble CD81 or the 3/11 neutralizing antibody was assessed. Surprisingly, none of these mutations, alone or in combination, conferred resistance to CBAs. In contrast, we observed that some mutants were more sensitive to 3/11 or CD81-LEL inhibition. Additionally, several mutations were identified in the Core and the non-structural proteins. Thus, our results suggest that in contrast to HIV, HCV resistance to CBAs is not directly conferred by mutations in the envelope protein genes but could occur through an indirect mechanism involving mutations in other viral proteins. Further investigations are needed to completely elucidate the underlying mechanisms.

Highlights

Hepatitis C virus (HCV) is a small positive single-stranded RNA virus that belongs to the Hepacivirus genus in the Flaviviridae family [1]
Since some of the mutations identified upon lectin exposure affected the N-glycosylation of E2 envelope protein which is known to protect the CD81 binding site from neutralizing antibodies, we investigated the mutant sensitivity to the 3/11 neutralizing monoclonal antibody (MAb) and to a soluble form of the CD81 large extracellular loop (CD81-LEL)
After more than eight weeks of HCV culture in the presence of increasing concentrations of different lectins, we identified several mutations in the genomes of the isolated strains, and evidenced a positive selection on the E1E2 coding region, as a consequence of the V284A, M338V, V392D, A400D, N417S, S449P and L612M non-synonymous mutations

Summary

Introduction

Hepatitis C virus (HCV) is a small positive single-stranded RNA virus that belongs to the Hepacivirus genus in the Flaviviridae family [1]. This enveloped virus infects hepatocytes and causes serious liver diseases in humans. Past treatment of HCV included the use of interferon and ribavirin, a combination that was not very effective and not well tolerated. HCV Resistance to CBAs era started in 2014 thanks to the development of direct-acting antiviral arsenal which enables to achieve a sustained virologic response in more than 90% of treated patients in clinical trials [2]. Some concerns remain such as access to care in low- to middleincome countries or viral resistance that could be encountered in real-life less-compliant populations

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