Anti-hepatitis C virus T-cell immunity in the context of multiple exposures to the virus

PLoS One. 2015 Jun 24;10(6):e0130420. doi: 10.1371/journal.pone.0130420. eCollection 2015.

Abstract

Characterisation of Hepatitis C virus (HCV)-specific CD8+ T-cell responses in the context of multiple HCV exposures is critical to identify broadly protective immune responses necessary for an effective HCV vaccine against the different HCV genotypes. However, host and viral genetic diversity complicates vaccine development. To compensate for the observed variation in circulating autologous viruses and host molecules that restrict antigen presentation (human leucocyte antigens; HLA), this study used a reverse genomics approach that identified sites of viral adaptation to HLA-restricted T-cell immune pressure to predict genotype-specific HCV CD8+ T-cell targets. Peptides representing these putative HCV CD8+ T-cell targets, and their adapted form, were used in individualised IFN-γ ELISpot assays to screen for HCV-specific T-cell responses in 133 HCV-seropositive subjects with high-risk of multiple HCV exposures. The data obtained from this study i) confirmed that genetic studies of viral evolution is an effective approach to detect novel in vivo HCV T-cell targets, ii) showed that HCV-specific T-cell epitopes can be recognised in their adapted form and would not have been detected using wild-type peptides and iii) showed that HCV-specific T-cell (but not antibody) responses against alternate genotypes in chronic HCV-infected subjects are readily found, implying clearance of previous alternate genotype infection. In summary, HCV adaptation to HLA Class I-restricted T-cell responses plays a central role in anti-HCV immunity and multiple HCV genotype exposure is highly prevalent in at-risk exposure populations, which are important considerations for future vaccine design.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Alleles
  • CD8-Positive T-Lymphocytes / immunology*
  • CD8-Positive T-Lymphocytes / virology
  • Cohort Studies
  • Enzyme-Linked Immunospot Assay
  • Epitopes, T-Lymphocyte / chemistry
  • Female
  • Genomics
  • Genotype
  • HLA Antigens / immunology
  • Hepacivirus*
  • Hepatitis C / immunology*
  • Hepatitis C / virology
  • Hepatitis C, Chronic / immunology*
  • Hepatitis C, Chronic / virology
  • Humans
  • Male
  • Peptides / chemistry

Substances

  • Epitopes, T-Lymphocyte
  • HLA Antigens
  • Peptides

Grants and funding

The work presented in this manuscript was supported by the Haemophilia Foundation of Australia, the McCusker Research Foundation and the Raine Medical Research Foundation. Microsoft Research, Microsoft, Redmond, Washington, USA provided support in the form of salaries for author DH, but did not have any additional role in the study design, data collection and analysis, decision to publish, or preparation of the manuscript. The specific roles of these authors are articulated in the ‘author contributions’ section.