HOMEPRODUCTSCOMPANYCONTACTFAQResearchDictionaryPharmaSign Up FREE or Login

Amino Acid Substitutions within HLA-B*27-Restricted T Cell Epitopes Prevent Recognition by Hepatitis Delta Virus-Specific CD8+ T Cells.

Abstract
Virus-specific CD8 T cell response seems to play a significant role in the outcome of hepatitis delta virus (HDV) infection. However, the HDV-specific T cell epitope repertoire and mechanisms of CD8 T cell failure in HDV infection have been poorly characterized. We therefore aimed to characterize HDV-specific CD8 T cell epitopes and the impacts of viral mutations on immune escape. In this study, we predicted peptide epitopes binding the most frequent human leukocyte antigen (HLA) types and assessed their HLA binding capacities. These epitopes were characterized in HDV-infected patients by intracellular gamma interferon (IFN-γ) staining. Sequence analysis of large hepatitis delta antigen (L-HDAg) and HLA typing were performed in 104 patients. The impacts of substitutions within epitopes on the CD8 T cell response were evaluated experimentally and by in silico studies. We identified two HLA-B*27-restricted CD8 T cell epitopes within L-HDAg. These novel epitopes are located in a relatively conserved region of L-HDAg. However, we detected molecular footprints within the epitopes in HLA-B*27-positive patients with chronic HDV infections. The variant peptides were not cross-recognized in HLA-B*27-positive patients with resolved HDV infections, indicating that the substitutions represent viral escape mutations. Molecular modeling of HLA-B*27 complexes with the L-HDAg epitope and its potential viral escape mutations indicated that the structural and electrostatic properties of the bound peptides differ considerably at the T cell receptor interface, which provides a possible molecular explanation for the escape mechanism. This viral escape from the HLA-B*27-restricted CD8 T cell response correlates with a chronic outcome of hepatitis D infection. T cell failure resulting from immune escape may contribute to the high chronicity rate in HDV infection.IMPORTANCE Hepatitis delta virus (HDV) causes severe chronic hepatitis, which affects 20 million people worldwide. Only a small number of patients are able to clear the virus, possibly mediated by a virus-specific T cell response. Here, we performed a systematic screen to define CD8 epitopes and investigated the role of CD8 T cells in the outcome of hepatitis delta and how they fail to eliminate HDV. Overall the number of epitopes identified was very low compared to other hepatotropic viruses. We identified, two HLA-B*27-restricted epitopes in patients with resolved infections. In HLA-B*27-positive patients with chronic HDV infections, however, we detected escape mutations within these identified epitopes that could lead to viral evasion of immune responses. These findings support evidence showing that HLA-B*27 is important for virus-specific CD8 T cell responses, similar to other viral infections. These results have implications for the clinical prognosis of HDV infection and for vaccine development.
AuthorsHadi Karimzadeh, Muthamia M Kiraithe, Anna D Kosinska, Manuel Glaser, Melanie Fiedler, Valerie Oberhardt, Elahe Salimi Alizei, Maike Hofmann, Juk Yee Mok, Melanie Nguyen, Wim J E van Esch, Bettina Budeus, Jan Grabowski, Maria Homs, Antonella Olivero, Hossein Keyvani, Francisco Rodríguez-Frías, David Tabernero, Maria Buti, Andreas Heinold, Seyed Moayed Alavian, Tanja Bauer, Julian Schulze Zur Wiesch, Bijan Raziorrouh, Daniel Hoffmann, Antonina Smedile, Mario Rizzetto, Heiner Wedemeyer, Jörg Timm, Iris Antes, Christoph Neumann-Haefelin, Ulrike Protzer, Michael Roggendorf
JournalJournal of virology (J Virol) Vol. 92 Issue 13 (07 01 2018) ISSN: 1098-5514 [Electronic] United States
PMID29669837 (Publication Type: Journal Article, Research Support, Non-U.S. Gov't)
CopyrightCopyright © 2018 American Society for Microbiology.
Chemical References
  • Epitopes, T-Lymphocyte
  • HLA-B Antigens
  • Hepatitis delta Antigens
  • hepatitis delta virus large antigen
Topics
  • Amino Acid Sequence
  • Amino Acid Substitution
  • CD8-Positive T-Lymphocytes (immunology, metabolism)
  • Epitopes, T-Lymphocyte (immunology, metabolism)
  • HLA-B Antigens (genetics, immunology, metabolism)
  • Hepatitis D (genetics, immunology, virology)
  • Hepatitis Delta Virus (genetics, immunology)
  • Hepatitis delta Antigens (immunology, metabolism)
  • Humans
  • Mutation
  • Sequence Homology

Join CureHunter, for free Research Interface BASIC access!

Take advantage of free CureHunter research engine access to explore the best drug and treatment options for any disease. Find out why thousands of doctors, pharma researchers and patient activists around the world use CureHunter every day.
Realize the full power of the drug-disease research graph!


Choose Username:
Email:
Password:
Verify Password:
Enter Code Shown: