title: Clinical significance of in vitro replication-enhancing mutations of the hepatitis C virus (HCV) replicon in patients with chronic HCV infection.
abstract: BACKGROUND
  Mutations in nonstructural (NS) hepatitis C virus (HCV) proteins enhance replication in HCV-1a/b replicons. The prevalence of such mutations and their clinical significance in vivo are unknown.
  
  
  METHODS
  Parts of HCV NS3 and NS4B-NS5B genes that included 31 in vitro replication-enhancing sites were sequenced for 26 patients with chronic HCV genotype 1 infection.
  
  
  RESULTS
  Five patients showed specific mutations within NS3 at sites enhancing replication in the replicon. Those mutations were associated with a slower decrease in HCV RNA concentration during interferon (IFN)- alpha -based therapy (P = .007). Neither specific nor other mutations within NS3 and NS4B-NS5B were associated with baseline HCV RNA concentrations. Within NS5A, fewer mutations in the major HCV strain (P = .001) and increased quasi-species complexity (P = .02) and diversity (P = .02) correlated with increasing baseline HCV RNA concentrations. In silico analyses of NS3 protein structures suggested that the majority of observed mutations did not lead to major conformational changes.
  
  
  CONCLUSIONS
  Specific mutations leading to enhanced replication in the replicon system were detected in 5 of 26 patients in vivo and were not associated with baseline HCV RNA concentrations but were associated with a slower decrease in HCV RNA concentration during IFN- alpha -based therapy. Quasi-species heterogeneity of NS5A correlated with baseline HCV RNA concentrations.
authors.affiliation: Klinik für Innere Medizin II, Universität des Saarlandes, Homburg/Saar, Germany. christoph.sarrazin@uniklinik-saarland.de
authors.forename: Christoph
authors.initials: C
authors.lastname: Sarrazin
authors.forename: Ulrike
authors.initials: U
authors.lastname: Mihm
authors.forename: Eva
authors.initials: E
authors.lastname: Herrmann
authors.forename: Christoph
authors.initials: C
authors.lastname: Welsch
authors.forename: Mario
authors.initials: M
authors.lastname: Albrecht
authors.forename: Ulrike
authors.initials: U
authors.lastname: Sarrazin
authors.forename: Stella
authors.initials: S
authors.lastname: Traver
authors.forename: Thomas
authors.initials: T
authors.lastname: Lengauer
authors.forename: Stefan
authors.initials: S
authors.lastname: Zeuzem
mesh_terms: D000328:Adult; D000368:Aged; D000595:Amino Acid Sequence; D000998:Antiviral Agents / Q000627:therapeutic use; D005260:Female; D016174:Hepacivirus / Q000235:genetics / Q000502:physiology*; D019698:Hepatitis C, Chronic / Q000188:drug therapy / Q000821:virology*; D006801:Humans; D007371:Interferon-gamma / Q000627:therapeutic use; D008297:Male; D008875:Middle Aged; D008958:Models, Molecular; D008969:Molecular Sequence Data; D009154:Mutation; D012367:RNA, Viral / Q000097:blood; D012093:Replicon; D017422:Sequence Analysis, DNA; D014779:Virus Replication / Q000187:drug effects
chemical_list: D000998:Antiviral Agents; D012367:RNA, Viral; D007371:Interferon-gamma