title: Analysis of CD8+ T-cell-mediated inhibition of hepatitis C virus replication using a novel immunological model.
abstract: OBJECTIVE
  Virus-specific CD8+ T cells are required for the control of hepatitis C virus (HCV) infection. We investigated the extent to which different effector functions of CD8+ T cells contribute to the inhibition of viral replication.
  
  
  METHODS
  We developed a novel immunologic model by stably transducing the HLA-A2 gene into the replicon system, matching the epitope sequence of the replicon to the sequence targeted by an HCV-specific CD8+ T-cell clone. Luciferase activity was then measured to quantitate HCV RNA replication.
  
  
  RESULTS
  HCV-specific CD8+ T cells strongly inhibited viral replication, through cytolytic and noncytolytic mechanisms, in a dose-dependent manner. HCV replication was almost completely inhibited at an effector-to-target ratio of 1:1 with significant cytotoxicity; however, >95% viral inhibition occurred at ratios as low as 1:100. Importantly, no cytotoxicity was observed at low effector-to-target ratios, indicating a dominant effect of noncytolytic effector functions that was confirmed by Transwell experiments. Neutralization experiments revealed that interferon gamma mediates the noncytolytic inhibition.
  
  
  CONCLUSIONS
  Only a very few HCV-specific CD8+ T cells are required to inhibit HCV replication; inhibition occurs primarily by noncytolytic effector functions.
authors.affiliation: Department of Medicine II, University Hospital Freiburg, and Faculty of Biology, Spemann Graduate School of Biology and Medicine, Albert Ludwigs University, Freiburg, Germany.
authors.forename: Juandy
authors.initials: J
authors.lastname: Jo
authors.forename: Ulrike
authors.initials: U
authors.lastname: Aichele
authors.forename: Nadine
authors.initials: N
authors.lastname: Kersting
authors.forename: Rahel
authors.initials: R
authors.lastname: Klein
authors.forename: Peter
authors.initials: P
authors.lastname: Aichele
authors.forename: Emmanuel
authors.initials: E
authors.lastname: Bisse
authors.forename: Andrew K
authors.initials: AK
authors.lastname: Sewell
authors.forename: Hubert E
authors.initials: HE
authors.lastname: Blum
authors.forename: Ralf
authors.initials: R
authors.lastname: Bartenschlager
authors.forename: Volker
authors.initials: V
authors.lastname: Lohmann
authors.forename: Robert
authors.initials: R
authors.lastname: Thimme
mesh_terms: D018414:CD8-Positive T-Lymphocytes / Q000378:metabolism / Q000502:physiology* / Q000821:virology*; D006528:Carcinoma, Hepatocellular / Q000378:metabolism / Q000473:pathology; D045744:Cell Line, Tumor; D018984:Epitopes, T-Lymphocyte / Q000235:genetics; D015789:HLA-A2 Antigen / Q000235:genetics / Q000378:metabolism; D016174:Hepacivirus / Q000502:physiology*; D006526:Hepatitis C / Q000276:immunology / Q000378:metabolism; D006801:Humans; D007371:Interferon-gamma / Q000378:metabolism; D008113:Liver Neoplasms / Q000378:metabolism / Q000473:pathology; D018448:Models, Immunological; D012093:Replicon / Q000235:genetics; D014161:Transduction, Genetic; D017361:Viral Nonstructural Proteins / Q000235:genetics; D014779:Virus Replication / Q000502:physiology*; D012324:RNA-Dependent RNA Polymerase
chemical_list: D018984:Epitopes, T-Lymphocyte; D015789:HLA-A2 Antigen; D007371:Interferon-gamma; D017361:Viral Nonstructural Proteins; C087036:NS-5 protein, hepatitis C virus; D012324:RNA-Dependent RNA Polymerase