Hepatitis D virus-specific CD8+ T cells have a memory-like phenotype associated with viral immune escape in patients with chronic hepatitis D virus infection

H Kefalakes, C Koh, J Sidney, G Amanakis, A Sette… - Gastroenterology, 2019 - Elsevier
Gastroenterology, 2019Elsevier
Background & Aim Hepatitis D virus (HDV) superinfection of patients with chronic HBV
infection results in rapid progression to liver cirrhosis. Little is known about HDV-specific T
cells and how they contribute to the antiviral immune response and liver disease
pathogenesis. Methods We isolated peripheral blood mononuclear cells from 28 patients
with chronic HDV and HBV infection, identified HDV-specific CD8+ T-cell epitopes, and
characterized HDV-specific CD8+ T cells. We associated these with HDV sequence …
Background & Aim
Hepatitis D virus (HDV) superinfection of patients with chronic HBV infection results in rapid progression to liver cirrhosis. Little is known about HDV-specific T cells and how they contribute to the antiviral immune response and liver disease pathogenesis.
Methods
We isolated peripheral blood mononuclear cells from 28 patients with chronic HDV and HBV infection, identified HDV-specific CD8+ T-cell epitopes, and characterized HDV-specific CD8+ T cells. We associated these with HDV sequence variations and clinical features of patients.
Results
We identified 6 CD8+ T-cell epitopes; several were restricted by multiple HLA class I alleles. HDV-specific CD8+ T cells were as frequent as HBV-specific CD8+ T cells but were less frequent than T cells with specificity for cytomegalovirus, Epstein–Barr virus, or influenza virus. The ex vivo frequency of activated HDV-specific CD8+ T cells correlated with transaminase activity. CD8+ T-cell production of interferon gamma after stimulation with HDV peptides correlated inversely with HDV titer. HDV-specific CD8+ T cells did not express the terminal differentiation marker CD57, and fewer HDV-specific than Epstein–Barr virus–specific CD8+ T cells were 2B4+CD160+PD1+, a characteristic of exhausted cells. Approximately half of the HDV-specific CD8+ T cells had a memory-like PD1+CD127+TCF1hiT-betlow phenotype, which associated with HDV sequence variants with reduced HLA binding and reduced T-cell activation.
Conclusions
CD8+ T cells isolated from patients with chronic HDV and HBV infection recognize HDV epitopes presented by multiple HLA molecules. The subset of activated HDV-specific CD8+ T cells targets conserved epitopes and likely contributes to disease progression. The subset of memory-like HDV-specific CD8+ T cells is functional but unable to clear HDV because of the presence of escape variants. ClinicalTrials.gov, Numbers: NCT02511431, NCT00023322, NCT01495585, and NCT00001971. GenBank accession, Number: MK333199-333226
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