title: Barrier-Independent, Fitness-Associated Differences in Sofosbuvir Efficacy against Hepatitis C Virus.
abstract: Sofosbuvir displays a high phenotypic barrier to resistance, and it is a component of several combination therapies for hepatitis C virus (HCV) infections. HCV fitness can be a determinant of decreased sensitivity to direct-acting antiviral agents such as telaprevir or daclatasvir, but fitness-dependent decreased drug sensitivity has not been established for drugs with a high phenotypic barrier to resistance. Low- and high-fitness HCV populations and biological clones derived from them were used to infect Huh-7.5 hepatoma cells. Sofosbuvir efficacy was analyzed by measuring virus progeny production during several passages and by selection of possible sofosbuvir resistance mutations determined by sequencing the NS5B-coding region of the resulting populations. Sofosbuvir exhibited reduced efficacy against high-fitness HCV populations, without the acquisition of sofosbuvir-specific resistance mutations. A reduced sofosbuvir efficacy, similar to that observed with the parental populations, was seen for high-fitness individual biological clones. In independently derived high-fitness HCV populations or clones passaged in the presence of sofosbuvir, M289L was selected as the only substitution in the viral polymerase NS5B. In no case was the sofosbuvir-specific resistance substitution S282T observed. High HCV fitness can lead to decreased sensitivity to sofosbuvir, without the acquisition of specific sofosbuvir resistance mutations. Thus, fitness-dependent drug sensitivity can operate with HCV inhibitors that display a high barrier to resistance. This mechanism may underlie treatment failures not associated with selection of sofosbuvir-specific resistance mutations, linked to in vivo fitness of pretreatment viral populations.
authors.affiliation: Centro de Biología Molecular Severo Ochoa (CSIC-UAM), Consejo Superior de Investigaciones Científicas, Campus de Cantoblanco, Madrid, Spain Centro de Investigación Biomédica en Red de Enfermedades Hepáticas y Digestivas, Barcelona, Spain.
authors.forename: Isabel
authors.initials: I
authors.lastname: Gallego
authors.affiliation: Centro de Biología Molecular Severo Ochoa (CSIC-UAM), Consejo Superior de Investigaciones Científicas, Campus de Cantoblanco, Madrid, Spain.
authors.forename: Julie
authors.initials: J
authors.lastname: Sheldon
authors.affiliation: Centro de Biología Molecular Severo Ochoa (CSIC-UAM), Consejo Superior de Investigaciones Científicas, Campus de Cantoblanco, Madrid, Spain.
authors.forename: Elena
authors.initials: E
authors.lastname: Moreno
authors.affiliation: Centro de Investigación Biomédica en Red de Enfermedades Hepáticas y Digestivas, Barcelona, Spain Liver Unit, Internal Medicine, Laboratory of Malalties Hepàtiques, Vall d'Hebron Institut de Recerca-Hospital Universitari Vall d'Hebron, Universitat Autònoma de Barcelona, Barcelona, Spain Roche Diagnostics, S.L., Sant Cugat del Vallés, Spain.
authors.forename: Josep
authors.initials: J
authors.lastname: Gregori
authors.affiliation: Centro de Investigación Biomédica en Red de Enfermedades Hepáticas y Digestivas, Barcelona, Spain Liver Unit, Internal Medicine, Laboratory of Malalties Hepàtiques, Vall d'Hebron Institut de Recerca-Hospital Universitari Vall d'Hebron, Universitat Autònoma de Barcelona, Barcelona, Spain Universitat Autónoma de Barcelona, Barcelona, Spain.
authors.forename: Josep
authors.initials: J
authors.lastname: Quer
authors.affiliation: Centro de Investigación Biomédica en Red de Enfermedades Hepáticas y Digestivas, Barcelona, Spain Liver Unit, Internal Medicine, Laboratory of Malalties Hepàtiques, Vall d'Hebron Institut de Recerca-Hospital Universitari Vall d'Hebron, Universitat Autònoma de Barcelona, Barcelona, Spain Universitat Autónoma de Barcelona, Barcelona, Spain.
authors.forename: Juan Ignacio
authors.initials: JI
authors.lastname: Esteban
authors.affiliation: Center for the Study of Hepatitis C, Laboratory of Virology and Infectious Disease, The Rockefeller University, New York, New York, USA.
authors.forename: Charles M
authors.initials: CM
authors.lastname: Rice
authors.affiliation: Centro de Biología Molecular Severo Ochoa (CSIC-UAM), Consejo Superior de Investigaciones Científicas, Campus de Cantoblanco, Madrid, Spain Centro de Investigación Biomédica en Red de Enfermedades Hepáticas y Digestivas, Barcelona, Spain.
authors.forename: Esteban
authors.initials: E
authors.lastname: Domingo
authors.affiliation: Centro de Biología Molecular Severo Ochoa (CSIC-UAM), Consejo Superior de Investigaciones Científicas, Campus de Cantoblanco, Madrid, Spain Centro de Investigación Biomédica en Red de Enfermedades Hepáticas y Digestivas, Barcelona, Spain Liver Unit, Internal Medicine, Laboratory of Malalties Hepàtiques, Vall d'Hebron Institut de Recerca-Hospital Universitari Vall d'Hebron, Universitat Autònoma de Barcelona, Barcelona, Spain cperales@cbm.csic.es.
authors.forename: Celia
authors.initials: C
authors.lastname: Perales
mesh_terms: D000998:Antiviral Agents / Q000494:pharmacology*; D045744:Cell Line, Tumor; D002999:Clone Cells; D024882:Drug Resistance, Viral / Q000235:genetics*; D015870:Gene Expression; D056084:Genetic Fitness; D005838:Genotype; D016174:Hepacivirus / Q000187:drug effects* / Q000235:genetics / Q000254:growth & development; D022781:Hepatocytes / Q000187:drug effects / Q000821:virology; D006801:Humans; D008826:Microbial Sensitivity Tests; D009154:Mutation; D009842:Oligopeptides / Q000494:pharmacology; D000069474:Sofosbuvir / Q000494:pharmacology*; D017361:Viral Nonstructural Proteins / Q000235:genetics*; D012324:RNA-Dependent RNA Polymerase
chemical_list: D000998:Antiviral Agents; D009842:Oligopeptides; D000069474:Sofosbuvir; D017361:Viral Nonstructural Proteins; C486464:telaprevir; C087036:NS-5 protein, hepatitis C virus; D012324:RNA-Dependent RNA Polymerase