Antibody Reactive to a Hepatitis C Virus (HCV)-Derived Peptide Capable of Inducing HLA-A2 Restricted Cytotoxic T Lymphocytes Is Detectable in a Majority of HCV-Infected Individuals without HLA-A2 Restriction

New Epitope Peptides Derived from Hepatitis C Virus (HCV) 2a Which Have the Capacity to Induce Cytotoxic T Lymphocytes in HLA-A2+HCV-Infected Patients

Because cytotoxic T lymphocytes (CTLs) play an important role in the specific immunotherapy of hepatitis C virus (HCV) infection, a series of CTL epitopes has been defined from HCV genotype 1a or 1b protein. Here, we attempted to identify HCV2a-derived epitopes that are capable of inducing HLA-A2-restricted and peptide-specific CTLs. Peripheral blood mononuclear cells (PBMCs) of HLA-A2+ HCV2ainfected patients or healthy donors were stimulated in vitro with each of the HCV2a-derived peptides, which were prepared based on the HLA-A2-binding motif, and their peptide-specific and HLA-A2-restricted cytotoxicities were examined. The HCV2a 432-441, HCV2a 716-724, and HCV2a 2251-2260 peptides were found to efficiently induce peptide-specific CTLs from the PBMCs of HLA-A2+ HCV2ainfected patients. Cytotoxicity was mainly mediated by CD8+ T cells in a HLA class I-restricted manner. These results indicate that the HCV2a 432-441, HCV2a 716-724, and HCV2a 2251-2260 peptides might be applicable for peptide-based immunotherapy of HLA-A2+ HCV2a-infected patients.

Phase I clinical study of a peptide vaccination for hepatitis C virus-infected patients with different human leukocyte antigen-class I-A alleles

Hepatitis C virus (HCV) infection has a high risk of liver cirrhosis and hepatocellular carcinoma at later stages. We recently identified a peptide derived from the HCV core protein capable of inducing both cellular and humoral responses to nearly all HCV-positive patients in Japan with different human leukocyte antigen (HLA)-class I-A alleles. To assess the safety and immune responses to this novel peptide, we conducted a phase I dose-escalation study of the vaccination for 26 HCV-positive patients who were either non-responders to the interferon-based therapy (n = 23) or refused it (n = 3). The regimen was well tolerated, with no severe vaccine-related toxicity. Twenty-five and 22 patients completed the first and second cycle vaccination (6 and 12 vaccine injections), respectively. After a series of six vaccine injections, peptide-specific CTL activity was augmented in peripheral blood mononuclear cells from 15 of 25 patient samples, with an expected optimal dose of 1 mg peptide. After 12 vaccine injections, peptide-specific IgG production was augmented in plasma from the majority of patients (15 of 22 patients) tested, but not in a dose-dependent fashion. There were two HCV RNA responders with >1 log declines. Among patients whose pre-vaccination levels of alanine aminotransferase and alpha feto-protein exceeded the normal ranges, a <30% decrease was found in 7 of 24 and three of six patients, respectively. Because of its tolerability and higher rate of immune boosting, this protocol is recommended for a phase II study to investigate its clinical efficacy.

A peptide derived from hepatitis C virus (HCV) core protein inducing cellular responses in patients with HCV with various HLA class IA alleles

C35-44 peptide is a well known HLA-A2-restricted CTL epitope originating from hepatitis C virus (HCV) core protein. It was reported that the majority of HCV positive patients had significant levels of serum IgG specific to this peptide. This study addressed whether C35-44 peptide could induce CTL activity restricted to various HLA class IA alleles or could not. This peptide demonstrated binding activity to HLA-A*2402, -A*2601, -A*3101, and -A*3303 molecules, but not to HLA-A*1101 by means of stabilization assay. This peptide also induced CTL activity restricted to each of them, except HLA-A11(+) peripheral blood mononuclear cells from HCV 1b(+) patients by means of (51)Cr-release assay. With regard to HLA-A2 subtypes, this peptide demonstrated binding activity to HLA-A*0201 and -A*0206, but not to -A*0207 molecules. Furthermore, this peptide induced CTL activity from both the patients and healthy donors with all the HLA class IA molecules mentioned above by means of interferon-gamma production assay. These results may provide new insights for the development of a novel peptide vaccine against HCV compatible with various HLA class IA types.

Recent advances in cancer vaccines: an overview

The field of cancer vaccines is currently in an active state of clinical investigations. Human papilloma virus vaccine has been approved as a prophylactic cancer vaccine, while Oncophage (heat shock protein-peptide complex) was recently approved in Russia for a certain stage of kidney cancer, although to date none has been approved in Japan or the USA. We reviewed recent clinical trials of several different types of cancer vaccines, mainly by using PubMed from 2005 to 2008. There have been slow but substantial advances in peptide vaccines and dendritic cell-based vaccines with regard to both clinical responses and immunological markers. A personalized approach to boost immune responses, addition of chemotherapy to overcome robust cancers and changing of endpoints from tumor reduction to overall survival seem to be the three key elements for the development of therapeutic cancer vaccines.

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 hepatitis C virus (HCV) is pivotal for vaccine development. We previously reported that the majority of patients infected with HCV have significant levels of IgG specific to an HCV-derived peptide at positions 35-44 of core protein (C35-44), a major epitope recognized by cellular immunity. This study addresses whether or not the other subclasses of immunoglobulins to this peptide exist. As a result, IgE, but not IgM or IgA, specific to this peptide is consistently detectable in the majority of patients with HCV infection, regardless of the different HLA types and disease conditions. These results provide additional information on this immunogenic peptide with new insights that contribute to a better understanding of host responses to HCV.

A new epitope peptide derived from hepatitis C virus 1b possessing the capacity to induce cytotoxic T-lymphocytes in HCV1b-infected patients with HLA-A11, -A31, and -A33

BACKGROUND

Hepatitis C virus (HCV) frequently causes chronic hepatitis, cirrhosis, and hepatocellular carcinoma after long-term persistent infection. Among various genotypes of HCV, HCV1b is resistant to standard interferon therapy, and thus the development of new treatment modality is needed.

RESULTS

To provide a scientific basis for specific immunotherapy for HCV1b, we investigated HCV1b-derived epitope peptides recognized by human leukocyte antigen (HLA)-A11, -A31, or -A33-restricted cytotoxic T-lymphocytes (CTLs), and report here three novel vaccine candidate peptides selected by both antibody screening and CTL-inducing capacity from among 46 peptides of conserved regions of HCV1b sequences with binding motifs to HLA-A11, -A31, and -A33. Significant levels of IgG reactive to each of the three peptides were detected in the plasma of more than 50% of the HCV1b(+) patients. One peptide at positions 30-39 of the core protein induced peptide-specific CTLs from peripheral blood mononuclear cells (PBMCs) of HLA-A11(+), -A31(+), and -A33(+) patients. The other two peptides at positions 35-43 of the core protein and at positions 918-926 of the non-structural protein 2 also induced peptide-specific CTLs from the PBMCs of HLA-A11(+) and -A33(+) patients.

CONCLUSION

Therefore, the peptide at positions 30-39 of the core protein could be an appropriate target molecule of specific immunotherapy for all HLA-A11(+), -A31(+), and -A33(+) patients with HCV1b-related diseases.

Cancerogenic effect of different fragments of the hepatitis C virus core protein

The hepatitis C virus core protein plays an extremely important role in the hepatocarcinogenesis of hepatitis C virus. Little, however, is known about the oncogenic potency of fragments. Thus, the purpose of the present study is to investigate the cancerogenic effects of the different core protein fragments. Two series of recombinant plasmids containing hepatitis C virus core gene fragments encoding the different-length core protein were constructed using plasmid enhanced green fluorescent protein (pEGFP)-C1 and pcDNA3.1(+), respectively. Human hepatocyte L02 cells transiently transfected with pEGFP-C1-based plasmids were subjected to confocal laser scanning microscopy analysis to determine the localization of the different core protein fragments. The stably transfected L02 cells with the pcDNA3.1(+)-based core protein plasmids were used to investigate the ultrastructural effects of the core protein and the tumorigenicity of L02 cells expressing core protein fragments in athymic nude mice. The full-length core protein and Core130-191 were completely localized in the cytoplasm, while Core1-59 existed exclusively in the nucleus. On the other hand, Core50-140 and Core1-140 were observed in both the nucleus and the cytoplasm. Ultrastructural changes of L02 cells expressing the full-length core protein were comprehensive and included, for example, irregular nuclear, increased nuclear/cytoplasmic ratio and mitochondria swelling. The slight changes were observed in the cells expressing Core50-140 and Core130-191, whereas the ultrastructure of the cells expressing Core1-59 remained normal. All the L02 cells stably expressing different fragments of the core protein, with the exception of the C-terminal truncated fragment Core1-59, could induce the occurrence of tumor in the nude mice. The N-terminal fragment of the core protein, Core1-59, was not oncogenic, while the intermediate and posterior segments of the hepatitis C virus core protein had the cancerogenic potency. In view of the existence of many important immunogenic epitopes in it, the core protein anterior segment might be a safer candidate for the development of hepatitis C virus vaccine.

Identification of new immunogenic peptides in conserved regions of hepatitis C virus (HCV) 1b with the potentiality to generate cytotoxic T lymphocytes in HCV1b(+) HLA-A24(+) patients

AIM

Hepatitis C virus (HCV) 1b is resistant to standard interferon therapy and has a high risk of developing into hepatocellular carcinoma at the late stage of infection. Therefore, new therapeutic modalities for HCV1b infection must be developed. One approach would be active specific immunotherapy with highly immunogenic HCV1b peptides.

METHODS

HCV1b-derived 44 synthetic peptides were selected based on their binding scores to HLA-A24. Peptide-specific IgG were measured by ELISA. Peptide-specific cytotoxic T-lymphocytes (CTLs) were induced in vitro by repeated peptide-stimulation.

RESULTS

We identified three novel candidate peptides of HCV1b proteins containing HLA-A24 binding motifs. Each of them had the ability to induce HLA-A24-restricted and peptide-specific CTL activity, and IgGs specific to each of them were detected in the plasma of HCV1b patients. Among these three peptides, a peptide NS5A 2132-2142 was recognized by both cellular and humoral immunities in the majority of blood samples of patients tested. More importantly, the peptide-stimulated peripheral blood mononuclear cells (PBMCs) showed cytotoxicity against cells cotransfected with NS5A and HLA-A2402 genes in an HLA-restricted manner. This is an additional report to our previous study.

CONCLUSION

These findings may provide a new insight into the development of a peptide-based specific immunotherapy for HCV1b-infected patients.

Serum levels of IgG to the peptide of HCV1b core at positions 35-44 correlated with persistent infection, while levels of IgG to the peptide of NS5A at positions 2132-2140 correlated with better prognosis in HCV-infected patients

We previously reported that two IgG Abs to the hepatitis C virus (HCV), anti-core 35-44 (C35) and anti-NS5A 2132-2140 (NS5A2132), existed in the sera of the majority of patients with HCV infection. This study investigated if measuring the two Abs would facilitate the prediction of a patient's prognosis. The serum levels of anti-C35 were found to correlate with persistent infection, while those of anti-NS5A2132 correlated with a better prognosis in HCV-infected patients. These results suggest that sequential measurement of the two Abs together may provide new information for the prediction of prognosis.