Identification of CTL epitopes in hepatitis C virus by a genome-wide computational scanning and a rational design of peptide vaccine

Abstract

Developing a peptide-based vaccine for the highly variable hepatitis C virus (HCV) remains a challenging task. Variant viruses not only escape antigen presentation but also persist in a patient as quasi-species. Such variants are often antagonistic to the responding T cell repertoire. To overcome these problems, we herein propose a cocktail vaccine consisting of a few epitope peptides, which make it possible to outpace the emergence of variant viruses. To design such a vaccine, we developed a way to identify HLA-A*2402-binding peptides efficiently by means of the computational scanning of the whole genome of the pathogen. Most of the predicted peptides exhibited strong binding to the HLA-A*2402 molecule, while also inducing CD8 T cell responses from the patients' peripheral blood mononuclear cells (PBMCs). Peptide-induced T cells were capable of lysing HCV-expressing HepG2 cells which process antigens endogenously. The amount of HCV core antigen in the patients' livers suggested that the lytic activity of the peptide-induced T cells was clearly in a range suitable for therapeutic use. If T cells were activated under optimal conditions by high density peptides, then they tended to be relatively tolerant of single amino acid variations for cytolysis. Finally, an analysis of the viral population isolated in Japan suggested no obvious changes due to immune evasion in the viral genome even in a host population highly biased toward HLA-A*2402.

Induction of Cell-Mediated Immune Responses in Mice by DNA Vaccines That Express Hepatitis C Virus NS3 Mutants Lacking Serine Protease and NTPase/RNA Helicase Activities

“…4). All but H57A mutation of NS3 examined in this study are located outside the human CD4 and CD8 epitopes reported so far, with the H57A mutation being located at the C-terminal edge of an epitope [7], [8], [9], [11]. Therefore, these findings suggest that a single mutation in the protease and NTPase/RNA helicase domains would not interfere with immunogenicity of NS3 as a whole in mice and human.…”

“…NS3 is known to carry a variety of CD4 + and CD8 + T cell epitopes to induce strong HCV-specific T cell responses, which are correlated with viral clearance and resolution of acute HCV infection [7], [8], [9], [10], [11]. Also, the HCV core protein is known to carry a variety of CD4 + and CD8 + epitopes [7], [8], [9], [12], [13], [14]. From the antigenic point of view, therefore, NS3 and the core protein would be attractive candidates to be used for therapeutic vaccines that elicit T cell-mediated immune responses against HCV.…”

Bolstering the Number and Function of HSV-1–Specific CD8+ Effector Memory T Cells and Tissue-Resident Memory T Cells in Latently Infected Trigeminal Ganglia Reduces Recurrent Ocular Herpes Infection and Disease

“…Cutting-edge technologies and screening strategies have been developed recently to mine genomic sequence information for state-of-the-art rational vaccine design (40). However, the large size of the HSV-1 genome and the low frequency of HSV-specific CD8 + T cells have hampered genome-wide identification of protective HSV-1 CD8 + T cell epitopes and characterization of the full repertoire of CD8 + T cells that are associated with the “natural protective immunity" seen in ASYMP individuals.…”

“…Betts and colleagues have described the CD107 a/b assay as an alternative cytotoxicity assay that is able to address some of the shortcomings of the 51 Cr release assay. The intracellular assay to detect IFN-γ and CD107 a/b in response to in vitro peptide stimulations was performed as described (40, 42) with a few modifications. On the day of the assay, 1×10 6 PBMCs were stimulated in vitro with peptide pools (10µg/ml/peptide) at 37°C for additional 6 hrs in a 96-well plate with BD Golgi Stop (BD Biosciences), 10 µl of CD107 a FITC and CD107 b FITC.…”

Detection of IgE Antibody Specific to a Hepatitis C Virus–Derived Peptide Being Recognized by Cellular Immunity in Patients with HCV Infection

“…The determination of immunogenic peptides of HCV is pivotal for vaccine development, a long-awaited treatment modality. Thus, extensive studies were carried out in the past decade to find immunogenic HCV peptides capable of inducing immune responses (2,9,10,14,(15)(16)(17)(18)(19). As a result, an HCV-derived peptide at positions 35-44 of core protein (C35-44) was determined to be highly immunogenic because of its ability to induce cytotoxic T lymphocytes in HLA-A2-positive HCV-positive patients (2,15,16).…”