Virological and immunological determinants of intrahepatic virus-specific CD8+ T-cell failure in chronic hepatitis C virus infection

Abstract

Virus-specific CD8؉ T-cells play an important role in the outcome of acute hepatitis C virus (HCV) infection. In the chronic phase, however, HCV can persist despite the presence of virusspecific T-cell responses. Therefore, we set out to perform a full-breadth analysis of the intrahepatic virus-specific CD8؉ T-cell response, its relation to the peripheral T-cell response, and the overall influence of viral escape and the genetic restriction on intrahepatic CD8؉ T-cell failure. Intrahepatic and peripheral CD8؉ T-cells from 20 chronically HCV infected patients (genotype 1) were comprehensively analyzed using overlapping peptides spanning the entire HCV polyprotein in concert with autologous viral sequences that were obtained for all targeted regions. HCV-specific CD8؉ T-cell responses were detectable in most (90%) chronically HCV-infected patients, and two thirds of these responses targeted novel previously undescribed epitopes. Most of the responses were detectable only in the liver but not in the peripheral blood, indicating accumulation and enrichment at the site of disease. Of note, only approximately half of the responses were associated with viral sequence variations supported by functional analysis as viral escape mutations. Escape mutations were more often associated with HLA-B alleles. Conclusion: Our results show an unexpected high frequency of intrahepatic virus-specific CD8؉ T-cells, a large part of which continue to target the present viral antigens. Thus, our results suggest that factors other than mutational escape contribute to the failure of intrahepatic virus-specific CD8؉ T-cells.

Loss of viral fitness and cross-recognition by CD8+ T cells limit HCV escape from a protective HLA-B27–restricted human immune response

“…Viral escape mutations within the immunodominant HLA-B27-restricted HCV-specific CD8 + T cell epitope NS5B 2841-2849 (ARMILMTHF) occur in the vast majority of patients in clusters ( Figure 1A; clonal sequence data are shown in Supplemental Figure 1; supplemental material available online with this article; doi:10.1172/JCI36587DS1); e.g., viruses analyzed in 11 of 15 patients showed 2 or 3 mutations (6 patients with 2 mutations; 5 patients with 3 mutations), while viruses in only 4 patients showed no or only 1 mutation within the otherwise highly conserved epitope region. This is a striking finding, since T cell escape mutations forced by other HLA alleles typically harbor a single (90% and 81%), less frequently 2 (10% and 17%), and rarely 3 amino acid substitutions (0% and 3%), as has been shown in comprehensive analyses of patients with acute (22)(23)(24)(25)(26)(27) or chronic (24,(28)(29)(30)(31)(32)(33) HCV infection (P < 0.0001; Figure 1B). In addition, escape mutations within the dominant HLA-B27 epitope were observed…”

“…Sequences for HLA-B27 -subjects were taken from the literature: for acute HCV infection, longitudinal sequences or sequences from a known donor and the patient were compared (22)(23)(24)(25)(26)(27), while for chronic HCV infection, patient sequences were compared with genotype/subtype-matched consensus sequences (24,(28)(29)(30)(31)(32)(33). Sequences in HLA-B27 + patients with chronic HCV infection were included from this study ( Figure 1A) and from a previous, independent report (32).…”

Lack of ex vivo peripheral and intrahepatic α‐fetoprotein‐specific CD4+ responses in hepatocellular carcinoma

“…S2) and is in line with previous observations of our group for both, HCV-specific CD4þ and CD8þ T-cell responses. 21,22 Assays were performed on fresh PBMC and for some selected samples on cryopreserved cells.…”

“…The expansion is needed to obtain a sufficient number of intratumoral T cells for analysis, and the same approach has been successfully used in HCV immunobiology. 22,24,25 All nonspecifically expanded PBMC and intratumoral lymphocytes were used fresh.…”

Functional Attributes of Responding T Cells in HCV Infection: The Recent Advances in Engineering Functional Antiviral T Cells

“…In addition, it is noted later on in the chronic phase of infection that most of the T cell responses were detectable only in the liver but not in peripheral blood, indicating T cell accumulation and enrichment at the site of disease. In spite of this, only a small fraction, as low as 0-5 %, of CD8 liver T cells appears to be HCV-specific (mean: 0.4 %) (Neumann-Haefelin et al 2008;Spangenberg et al 2005). Thus, it seems that the majority of CD8…”