Analysis of CD8+ T-cell-mediated inhibition of hepatitis C virus replication using a novel immunological model

Gastroenterology. 2009 Apr;136(4):1391-401. doi: 10.1053/j.gastro.2008.12.034. Epub 2008 Dec 13.

Abstract

Background & aims: 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.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • CD8-Positive T-Lymphocytes / metabolism
  • CD8-Positive T-Lymphocytes / physiology*
  • CD8-Positive T-Lymphocytes / virology*
  • Carcinoma, Hepatocellular / metabolism
  • Carcinoma, Hepatocellular / pathology
  • Cell Line, Tumor
  • Epitopes, T-Lymphocyte / genetics
  • HLA-A2 Antigen / genetics
  • HLA-A2 Antigen / metabolism
  • Hepacivirus / physiology*
  • Hepatitis C / immunology
  • Hepatitis C / metabolism
  • Humans
  • Interferon-gamma / metabolism
  • Liver Neoplasms / metabolism
  • Liver Neoplasms / pathology
  • Models, Immunological*
  • Replicon / genetics
  • Transduction, Genetic
  • Viral Nonstructural Proteins / genetics
  • Virus Replication / physiology*

Substances

  • Epitopes, T-Lymphocyte
  • HLA-A2 Antigen
  • NS-5 protein, hepatitis C virus
  • Viral Nonstructural Proteins
  • Interferon-gamma