Phase I clinical study of a personalized peptide vaccination for patients infected with hepatitis C virus (HCV) 1b who failed to respond to interferon-based therapy

Development of therapeutic vaccines for the treatment of diseases

Vaccines are one of the most effective medical interventions to combat newly emerging and re-emerging diseases. Prophylactic vaccines against rabies, measles, etc., have excellent effectiveness in preventing viral infection and associated diseases. However, the host immune response is unable to inhibit virus replication or eradicate established diseases in most infected people. Therapeutic vaccines, expressing specific endogenous or exogenous antigens, mainly induce or boost cell-mediated immunity via provoking cytotoxic T cells or elicit humoral immunity via activating B cells to produce specific antibodies. The ultimate aim of a therapeutic vaccine is to reshape the host immunity for eradicating a disease and establishing lasting memory. Therefore, therapeutic vaccines have been developed for the treatment of some infectious diseases and chronic noncommunicable diseases. Various technological strategies have been implemented for the development of therapeutic vaccines, including molecular-based vaccines (peptide/protein, DNA and mRNA vaccines), vector-based vaccines (bacterial vector vaccines, viral vector vaccines and yeast-based vaccines) and cell-based vaccines (dendritic cell vaccines and genetically modified cell vaccines) as well as combinatorial approaches. This review mainly summarizes therapeutic vaccine-induced immunity and describes the development and status of multiple types of therapeutic vaccines against infectious diseases, such as those caused by HPV, HBV, HIV, HCV, and SARS-CoV-2, and chronic noncommunicable diseases, including cancer, hypertension, Alzheimer's disease, amyotrophic lateral sclerosis, diabetes, and dyslipidemia, that have been evaluated in recent preclinical and clinical studies.

Identification of promising CD8 and CD4 T cell epitopes for peptide vaccine formulation against SARS-CoV-2

The novel virus “severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2)” has been responsible for the worldwide pandemic causing huge devastation and deaths since December 2019. The disease caused by this virus is known as COVID-19. The present study is based on immuno-informatics approach to develop a multi-epitope-loaded peptide vaccine to combat the COVID-19 menace. Here, we have reported the 9-mer CD8 T cell epitopes and 15-mer CD4 T cell epitopes, free from glycosylation sites, belonging to three proteins, viz. surface glycoprotein, membrane glycoprotein and envelope protein of this virus. Immunogenicity, aliphatic amino acid, antigenicity and hydrophilicity scores of the predicted epitopes were estimated. In addition, other physicochemical parameters, namely net charge, Boman index and amino acid contents, were also accounted. Out of all the epitopes, three CD8 T cell epitopes viz. PDPSKPSKR, DPSKPSKRS and QTQTNSPRR and three CD4 T cell epitopes viz. ASYQTQTNSPRRARS, RIGNYKLNTDHSSSS and RYRIGNYKLNTDHSS were found to be efficient targets for raising immunity in human against this virus. With the help of our identified potent epitopes, various pharma industries might initiate efforts to incorporate those epitopes with carrier protein or adjuvant to develop a multi-epitope-loaded peptide vaccine against SARS-CoV-2. The peptide vaccines are usually cost-effective and therefore, could be administered as a preventive measure to combat the spread of this disease. Proper clinical trials must be conducted prior to the use of identified epitopes as vaccine candidates.

Interventions to reduce acute hepatitis C virus in HIV-positive MSM

PURPOSE OF REVIEW

The WHO has set ambitious targets for hepatitis C virus (HCV) elimination by 2030. In this review, we explore the possibility of HCV micro-elimination in HIV-positive (+) MSM, discussing strategies for reducing acute HCV incidence and the likely interventions required to meet these targets.

RECENT FINDINGS

With wider availability of directly acting antivirals (DAAs) in recent years, reductions in acute HCV incidence have been reported in some cohorts of HIV+ MSM. Recent evidence demonstrates that treatment in early infection is well tolerated, cost effective and may reduce the risk of onward transmission. Modelling studies suggest that to reduce incidence, a combination approach including behavioural interventions and access to early treatment, targeting both HIV+ and negative high-risk groups, will be required. HCV vaccine trials have not yet demonstrated efficacy in human studies, however phase one and two studies are ongoing.

SUMMARY

Some progress towards the WHO HCV elimination targets has been reported. Achieving sustained HCV elimination is likely to require a combination approach including early access to DAAs in acute infection and reinfection, validated and reproducible behavioural interventions and an efficacious HCV vaccine.

Review on chemogenomic approaches towards hepatitis C viral targets

Hepatitis C virus (HCV) is the most prevalent viral pathogen that infects more than 185 million people worldwide. HCV infection leads to chronic liver diseases such as liver cirrhosis and hepatocellular carcinoma. Direct-acting antivirals (DAAs) are the recent combination therapy for HCV infection with reduced side effects than prior therapies. Sustained virological response (SVR) acts as a gold standard marker to monitor the success of antiviral treatment. Older treatment therapies attain 50-55% of SVR compared with DAAs which attain around 90-95%. The current review emphasizes the recent chemogenomic updates that have been unfolded through structure-based drug design of HCV drug target proteins (NS3/4A, NS5A, and NS5B) and ligand-based drug design of DAAs in achieving a stable HCV viral treatment strategies.

Hepatitis C Virus Infection and Vaccine Development

In the twenty-seven years since the discovery of hepatitis C virus (HCV) the majority of individuals exposed to HCV establish a persistent infection, which is a leading cause of chronic liver disease, cirrhosis and hepatocellular carcinoma. In developed nations, the cure rates of HCV infection could be over 90% with direct-acting antiviral (DAA) regimens, which has made the great progress in global eradication. However, the cost of these treatments is so expensive that the patients in developing nations, where the disease burden is the most severe, could not afford it, which highly restricted its access. Additionally, the largely asymptomatic nature of infection facilitates continued transmission in risk groups due to limited surveillance. Consequently a protective vaccine and likely emergence of drug-resistant viral variants call for further studies of HCV biology. In the current review, the development and the progress of preventive and therapeutic vaccines against the HCV have been reviewed in the context of peptide vaccines, recombinant protein vaccines, HCV-like particle, DNA vaccines and viral vectors expressing HCV genes.

Global elimination of hepatitis C virus infection: Progresses and the remaining challenges

Today, with the introduction of interferon-free direct-acting antivirals and outstanding progresses in the prevention, diagnosis and treatment of hepatitis C virus (HCV) infection, the elimination of HCV infection seems more achievable. A further challenge is continued transmission of HCV infection in high-risk population specially injecting drug users (IDUs) as the major reservoir of HCV infection. Considering the fact that most of these infections remain undiagnosed, unidentified HCV-infected IDUs are potential sources for the rapid spread of HCV in the community. The continuous increase in the number of IDUs along with the rising prevalence of HCV infection among young IDUs is harbinger of a forthcoming public health dilemma, presenting a serious challenge to control transmission of HCV infection. Even the changes in HCV genotype distribution attributed to injecting drug use confirm this issue. These circumstances create a strong demand for timely diagnosis and proper treatment of HCV-infected patients through risk-based screening to mitigate the risk of HCV transmission in the IDUs community and, consequently, in the society. Meanwhile, raising general awareness of HCV infection, diagnosis and treatment through public education should be the core activity of any harm reduction intervention, as the root cause of failure in control of HCV infection has been lack of awareness among young drug takers. In addition, effective prevention, comprehensive screening programs with a specific focus on high-risk population, accessibility to the new anti-HCV treatment regimens and public education should be considered as the top priorities of any health policy decision to eliminate HCV infection.

Personalized neoantigen vaccines: A new approach to cancer immunotherapy

Neoantigens arise from somatic mutations that differ from wild-type antigens and are specific to each individual patient, which provide tumor specific targets for developing personalized cancer vaccines. Decades of work has increasingly shown the potential of targeting neoantigens to generate effective clinical responses. Current clinical trials using neoantigen targeting cancer vaccines, including in combination with checkpoint blockade monoclonal antibodies, have demonstrated potent T-cell responses against those neoantigens accompanied by antitumor effects in patients. Personalized neoantigen vaccines represent a potential new class of cancer immunotherapy.

Current status and future prospects of peptide-based cancer vaccines

Cancer immunotherapy has attracted attention worldwide owing to the recent development of immune checkpoint inhibitors. However, these therapies have shown limited efficacy, and further advancements are needed before these modalities can progress to widespread use. Immune checkpoint inhibitors are a type of nonspecific cancer immunotherapy, and antitumor effects are only observed when cancer-specific T cells are found within the nonspecifically activated T-cell group. In order to facilitate the development of potent immunotherapies, selective enhancement of cancer-specific T cells is essential. In this report, we discuss current and future perspectives, including the latest clinical trials of cancer-specific immunotherapies, particularly cancer peptide vaccines.

State of the Art, Unresolved Issues, and Future Research Directions in the Fight against Hepatitis C Virus: Perspectives for Screening, Diagnostics of Resistances, and Immunization

Hepatitis C virus (HCV) still represents a major public health threat, with a dramatic burden from both epidemiological and clinical points of view. New generation of direct-acting antiviral agents (DAAs) has been recently introduced in clinical practice promising to cure HCV and to overcome the issues related to the interferon-based therapies. However, the emergence of drug resistance and the suboptimal activity of DAAs therapies against diverse HCV genotypes have been observed, determining treatment failure and hampering an effective control of HCV spread worldwide. Moreover, these treatments remain poorly accessible, particularly in low-income countries. Finally, effective screening strategy is crucial to early identifying and treating all HCV chronically infected patients. For all these reasons, even though new drugs may contribute to impacting HCV spread worldwide a preventive HCV vaccine remains a cornerstone in the road to significantly reduce the HCV spread globally, with the ultimate goal of its eradication. Advances in molecular vaccinology, together with a strong financial, political, and societal support, will enable reaching this fundamental success in the coming years. In this comprehensive review, the state of the art about these major topics in the fight against HCV and the future of research in these fields are discussed.

Persistent hepatitis C viral replication despite priming of functional CD8+ T cells by combined therapy with a vaccine and a direct-acting antiviral

Exhaustion of antiviral CD8(+) T cells contributes to persistence of hepatitis C viral (HCV) infection. This immune response has proved difficult to restore by therapeutic vaccination, even when HCV replication is suppressed using antiviral regimens containing type I interferon. Because immunomodulatory effects of type I interferon may be a factor in poor T-cell priming, we undertook therapeutic vaccination in two chronically infected chimpanzees during treatment with a direct-acting antiviral (DAA) targeting the HCV NS5b polymerase protein. Immunization with genetic vaccines encoding the HCV NS3-NS5b nonstructural proteins during DAA treatment resulted in a multifunctional CD8(+) T-cell response. However, these antiviral CD8(+) T cells did not prevent persistent replication of DAA-resistant HCV variants that emerged during treatment. Most vaccine-induced CD8(+) T cells targeted class I epitopes that were not conserved in the circulating virus. Exhausted intrahepatic CD8(+) T-cell targeting-conserved epitopes did not expand after vaccination, with a notable exception. A sustained, multifunctional CD8(+) T-cell response against at least one intact class I epitope was detected in blood after vaccination. Persistence of HCV was not due to mutational escape of this epitope. Instead, failure to control HCV replication was likely caused by localized exhaustion in the liver, where CD8(+) T-cell expression of the inhibitory receptor programmed cell death 1 increased 25-fold compared with those in circulation.

CONCLUSION

Treatment with a DAA during therapeutic vaccination provided transient control of HCV replication and a multifunctional T-cell response, primarily against nonconserved class I epitopes; exhaustion of liver-infiltrating CD8(+) T cells that target conserved epitopes may not be averted when DAA therapy fails prematurely due to emergence of resistant HCV variants.

Phase II Study of Personalized Peptide Vaccination with Both a Hepatitis C Virus-Derived Peptide and Peptides from Tumor-Associated Antigens for the Treatment of HCV-Positive Advanced Hepatocellular Carcinoma Patients

Objective. To evaluate safety and immune responses of personalized peptide vaccination (PPV) for hepatitis C virus- (HCV-) positive advanced hepatocellular carcinoma (HCC). Patients and Methods. Patients diagnosed with HCV-positive advanced HCC were eligible for this study. A maximum of four HLA-matched peptides were selected based on the preexisting IgG responses specific to 32 different peptides, which consisted of a single HCV-derived peptide at core protein positions 35-44 (C-35) and 31 peptides derived from 15 different tumor-associated antigens (TAAs), followed by subcutaneous administration once per week for 8 weeks. Peptide-specific cytotoxic T lymphocyte (CTL) and IgG responses were measured before and after vaccination. Results. Forty-two patients were enrolled. Grade 3 injection site skin reaction was observed in 2 patients, but no other PPV-related severe adverse events were noted. Peptide-specific CTL responses before vaccination were observed in only 3 of 42 patients, but they became detectable in 23 of 36 patients tested after vaccination. Peptide-specific IgG responses were also boosted in 19 of 36 patients. Peptide-specific IgG1 responses to both C-35 and TAA-derived peptides could be potentially prognostic for overall survival. Conclusion. Further clinical study of PPV would be warranted for HCV-positive advanced HCC, based on the safety and strong immune induction.

Peptide-pulsed dendritic cells induce the hepatitis C viral epitope-specific responses of naïve human T cells

Hepatitis C virus (HCV) is a major cause of liver disease. Spontaneous resolution of infection is associated with broad, MHC class I- (CD8(+)) and class II-restricted (CD4(+)) T cell responses to multiple viral epitopes. Only 20% of patients clear infection spontaneously, however, most develop chronic disease. The response to chemotherapy varies; therapeutic vaccination offers an additional treatment strategy. To date, therapeutic vaccines have demonstrated only limited success in clinical trials. Vector-mediated vaccination with multi-epitope-expressing DNA constructs provides an improved approach. Highly-conserved, HLA-A2-restricted HCV epitopes and HLA-DRB1-restricted immunogenic consensus sequences (ICS, each composed of multiple overlapping and highly conserved epitopes) were predicted using bioinformatics tools and synthesized as peptides. HLA binding activity was determined in competitive binding assays. Immunogenicity and the ability of each peptide to stimulate naïve human T cell recognition and IFN-γ production were assessed in cultures of total PBMCs and in co-cultures composed of peptide-pulsed dendritic cells (DCs) and purified T lymphocytes, cell populations derived from normal blood donors. Essentially all predicted HLA-A2-restricted epitopes and HLA-DRB1-restricted ICS exhibited HLA binding activity and the ability to elicit immune recognition and IFN-γ production by naïve human T cells. The ability of DCs pulsed with these highly-conserved HLA-A2- and -DRB1-restricted peptides to induce naïve human T cell reactivity and IFN-γ production ex vivo demonstrates the potential efficacy of a multi-epitope-based HCV vaccine targeted to dendritic cells.

WITHDRAWN: Immunogenicity and safety of HCV E1E2 peptide vaccine in chronically HCV-infected patients who did not respond to interferon based therapy

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Hepatitis C virus vaccines in the era of new direct-acting antivirals

Hepatitis C virus (HCV) infection is a major global health problem as it has a high propensity for establishing chronicity. Chronic HCV carriers are at risk of developing severe liver disease including fibrosis, cirrhosis and liver cancer. While treatment has considerably improved over the years, therapy is still only partially effective, and is plagued by side effects, which contribute to treatment failure and is expensive to manage. The drug development pipeline contains several compounds that hold promise to achieve the goal of a short and more tolerable therapy, and are also likely to improve treatment response rates. It remains to be seen, however, how potent antiviral drug cocktails will affect the hepatitis C burden worldwide. In resource-poor environments, considerable costs, inadequate infrastructure for medical supervision and distribution may diminish the impact of future therapies. Consequently, development of novel therapeutic and prophylactic strategies is imperative to contain HCV infection globally.

Cellular immunogenicity of a multi-epitope peptide vaccine candidate based on hepatitis C virus NS5A, NS4B and core proteins in HHD-2 mice

To develop a vaccine against hepatitis C virus (HCV), a multi-epitope peptide was synthesized from nonstructural proteins containing HLA-A2 epitopes inducing mainly responses in natural infection. The engineered vaccine candidate, VAL-44, consists of multiple epitopes from the HCV NS5A, NS4B and core proteins. Immunization with the VAL-44 peptide induced higher CTL responses than those by the smaller VL-20 peptide. VAL-44 induced antigen-specific IFN-γ-producing CD4+ T cells and CD8+ T cells. VAL-44 elicited a Th1-biased immune response with secretion of high amounts of IFN-γ and IL-2, compared with VL-20. These results suggest that VAL-44 can elicit strong cellular immune responses. The VAL-44 peptide stimulated IFN-γ production from viral-specific peripheral blood mononuclear cells (PBMCs) of patients infected with HCV. These results suggest that VAL-44 could be developed as a potential HCV multi-epitope peptide vaccine.

Prospects for prophylactic and therapeutic vaccines against hepatitis C virus

Natural cross-protective immunity is induced after spontaneous clearance of primary hepatitis C virus (HCV) infection. Although this suggests that effective prophylactic vaccines against HCV are possible, there are still several areas that require further study. Current data indicate that, at best, vaccine-induced immunity may not completely prevent HCV infection but rather prevent persistence of the virus. However, this may be an acceptable goal, because chronic persistence of the virus is the main cause of pathogenesis and the development of serious liver conditions. Therapeutic vaccine development is also highly challenging; however, strategies have been pursued in combination with current or new treatments in an effort to reduce the costs and adverse effects associated with antiviral therapy. This review summarizes the current state of HCV vaccines and the challenges faced for future development and clinical trial design.

Complete definition of immunological correlates of protection and clearance of hepatitis C virus infection: a relevant pending task for vaccine development

Hepatitis C virus (HCV) infects approximately 3% of global population. This pathogen is one of the main causes of chronic viral hepatitis, cirrhosis, and liver cancer, as well as the principal reason for liver transplant in Western countries. Therapy against HCV infection is effective in only half of treated patients. There is no vaccine available against HCV. Some vaccine candidates have reached the clinical trials but several factors, including the incomplete definition of immunological correlates of protection and treatment-related clearance have slowed down vaccine development. Precisely, the present review discusses the state of the art in the establishment of parameters related with immunity against HCV. Validity and limitations of the information accumulated from chimpanzees and other animal models, analysis of studies in humans infected with HCV, and relevance of aspects like type, strength, duration, and specificity of immune response related to successful outcome are evaluated in detail. Moreover, the immune responses induced in some clinical trials with vaccine candidates resemble the theoretical immunological correlates, raising questions about the validity of those correlates. When all facts are taken together, complete definition of immunological correlates for protection or treatment-related clearance is an urgent priority. A limited or wrong criterion with respect to this relevant matter might cause incorrect vaccine design and selection of immunization strategies or erroneous clinical evaluation.

Therapeutic vaccination against chronic hepatitis C virus infection

Approximately 170 million people worldwide are chronic carriers of Hepatitis C virus (HCV). To date, there is no prophylactic vaccine available against HCV. The standard-of-care therapy for HCV infection involves a combination of pegylated interferon-α and ribavirin. This therapy, which is commonly associated with side effects, has a curative rate varying from 43% (HCV genotype 1) to 80% (HCV genotype 2). In 2011, two direct-acting antiviral agents, telaprevir and boceprevir, were approved by the US Food and drug Administration and are now being used in combination with standard-of-care therapy in selected patients infected with HCV genotype 1. Although both drugs are promising, resulting in a shortening of therapy, these drugs also induce additional side effects and have reduced efficacy in patients who did not respond to standard-of-care previously. An alternative approach would be to treat HCV by stimulating the immune system with a therapeutic vaccine ideally aimed at (i) the eradication of HCV-infected cells and (ii) neutralization of infectious HCV particles. The challenge is to develop therapeutic vaccination strategies that are either at least as effective as antiviral drugs but with lower side effects, or vaccines that, when combined with antiviral drugs, can circumvent long-term use of these drugs thereby reducing their side effects. In this review, we summarize and discuss recent preclinical developments in the area of therapeutic vaccination against chronic HCV infection. Although neutralizing antibodies have been described to exert protective immunity, clinical studies on the induction of neutralizing antibodies in therapeutic settings are limited. Therefore, we will primarily discuss therapeutic vaccines which aim to induce effective cellular immune response against HCV.

Advances in hepatitis C virus vaccines, part two: advances in hepatitis C virus vaccine formulations and modalities

INTRODUCTION

Developing a vaccine against HCV is an important medical and global priority. Unavailability and potential dangers associated with using attenuated HCV viral particles for vaccine preparation have resulted in the use of HCV genes and proteins formulated in novel vaccine modalities.

AREAS COVERED

In part one of this review, advances in basic knowledge for HCV vaccine design were provided. Herein, a detailed and correlated patents (searched by Espacenet) and literatures (searched by Pubmed) review on HCV vaccine formulations and modalities is provided, including: subunit, DNA, epitopic-peptide/polytopic, live vector- and whole yeast-based vaccines. Less-touched areas in vaccine studies such as mucosal, plant-based, and chimeric HBV/HCV vaccines are also discussed. Furthermore, results of preclinical/clinical studies on selected HCV vaccines as well as pros and cons of different strategies are reviewed. Finally, potential strategies for creation and/or improvement of HCV vaccine formulations are discussed.

EXPERT OPINION

Promising outcomes of a few HCV vaccine modalities in phase I/II clinical trials predict the accessibility of at least partially effective vaccines to inhibit or treat the chronic state of HCV infection (specially in combination with standard antiviral therapy). ChronVac-C (plasmid DNA), TG4040 (MVA-based), and GI-5005 (whole yeast-based) might be the most obvious HCV vaccine candidates to be approved in the near future.

Vaccination for hepatitis C virus: closing in on an evasive target

Hepatitis C virus (HCV) infects more than 170 million people globally and is a leading cause of liver cirrhosis, transplantation and hepatocellular carcinoma. Current gold-standard therapy often fails, has significant side effects in many cases and is expensive. No vaccine is currently available. The fact that a significant proportion of infected people spontaneously control HCV infection in the setting of an appropriate immune response suggests that a vaccine for HCV is a realistic goal. A comparative analysis of infected people with distinct clinical outcomes has enabled the characterization of many important innate and adaptive immune processes associated with viral control. It is clear that a successful HCV vaccine will need to exploit and enhance these natural immune defense mechanisms. New HCV vaccine approaches, including peptide, recombinant protein, DNA and vector-based vaccines, have recently reached Phase I/II human clinical trials. Some of these technologies have generated robust antiviral immunity in healthy volunteers and infected patients. The challenge now is to move forward into larger at-risk or infected populations to truly test efficacy.

Hepatitis C therapy: other players in the game

Therapies in addition to the direct-acting antiviral agents (DAA) under evaluation for chronic hepatitis C include host targets such as cyclophilin inhibitors and immunomodulators. Both passive and therapeutic vaccines hold promise for the future. Although the numbers of drug categories and individual agents are increasing, only a handful of the non-DAAs seem to be ready to move on to phase III trials. New interferon agents are in development, and ribavirin variants are still under consideration. The role of the other players in the overall armamentarium against hepatitis C virus is still evolving.

An assessment of the use of chimpanzees in hepatitis C research past, present and future: 1. Validity of the chimpanzee model

The USA is the only significant user of chimpanzees in biomedical research in the world, since many countries have banned or limited the practice due to substantial ethical, economic and scientific concerns. Advocates of chimpanzee use cite hepatitis C research as a major reason for its necessity and continuation, in spite of supporting evidence that is scant and often anecdotal. This paper examines the scientific and ethical issues surrounding chimpanzee hepatitis C research, and concludes that claims of the necessity of chimpanzees in historical and future hepatitis C research are exaggerated and unjustifiable, respectively. The chimpanzee model has several major scientific, ethical, economic and practical caveats. It has made a relatively negligible contribution to knowledge of, and tangible progress against, the hepatitis C virus compared to non-chimpanzee research, and must be considered scientifically redundant, given the array of alternative methods of inquiry now available. The continuation of chimpanzee use in hepatitis C research adversely affects scientific progress, as well as chimpanzees and humans in need of treatment. Unfounded claims of its necessity should not discourage changes in public policy regarding the use of chimpanzees in US laboratories.

Recombinant infectious bursal disease virus carrying hepatitis C virus epitopes

The delivery of foreign epitopes by a replicating nonpathogenic avian infectious bursal disease virus (IBDV) was explored. The aim of the study was to identify regions in the IBDV genome that are amenable to the introduction of a sequence encoding a foreign peptide. By using a cDNA-based reverse genetics system, insertions or substitutions of sequences encoding epitope tags (FLAG, c-Myc, or hepatitis C virus epitopes) were engineered in the open reading frames of a nonstructural protein (VP5) and the capsid protein (VP2). Attempts were also made to generate recombinant IBDV that displayed foreign epitopes in the exposed loops (P(BC) and P(HI)) of the VP2 trimer. We successfully recovered recombinant IBDVs expressing c-Myc and two different virus-neutralizing epitopes of human hepatitis C virus (HCV) envelope glycoprotein E in the VP5 region. Western blot analyses with anti-c-Myc and anti-HCV antibodies provided positive identification of both the c-Myc and HCV epitopes that were fused to the N terminus of VP5. Genetic analysis showed that the recombinants carrying the c-Myc/HCV epitopes maintained the foreign gene sequences and were stable after several passages in Vero and 293T cells. This is the first report describing efficient expression of foreign peptides from a replication-competent IBDV and demonstrates the potential of this virus as a vector.

A phase I clinical trial of dendritic cell immunotherapy in HCV-infected individuals

BACKGROUND & AIMS

HCV patients who fail conventional interferon-based therapy have limited treatment options. Dendritic cells are central to the priming and development of antigen-specific CD4(+) and CD8(+) T cell immunity, necessary to elicit effective viral clearance. The aim of the study was to investigate the safety and efficacy of vaccination with autologous dendritic cells loaded with HCV-specific cytotoxic T cell epitopes.

METHODS

We examined the potential of autologous monocyte-derived dendritic cells (MoDC), presenting HCV-specific HLA A2.1-restricted cytotoxic T cell epitopes, to influence the course of infection in six patients who failed conventional therapy. Dendritic cells were loaded and activated ex vivo with lipopeptides. In this phase 1 dose escalation study, all patients received a standard dose of cells by the intradermal route while sequential patients received an increased dose by the intravenous route.

RESULTS

No patient showed a severe adverse reaction although all experienced transient minor side effects. HCV-specific CD8(+) T cell responses were enumerated in PBMC by ELIspot for interferon-gamma. Patients generated de novo responses, not only to peptides presented by the cellular vaccine but also to additional viral epitopes not represented in the lipopeptides, suggestive of epitope spreading. Despite this, no increases in ALT levels were observed. However, the responses were not sustained and failed to influence the viral load, the anti-HCV core antibody response and the level of circulating cytokines.

CONCLUSIONS

Immunotherapy using autologous MoDC pulsed with lipopeptides was safe, but was unable to generate sustained responses or alter the outcome of the infection. Alternative dosing regimens or vaccination routes may need to be considered to achieve therapeutic benefit.

Evaluation of a new oil adjuvant for use in peptide-based cancer vaccination

Vaccine therapies are increasingly being used for the treatment of various diseases, and the antigen molecules themselves are being expanded from whole microorganisms to fine molecules such as peptides. Accordingly, there is a need for new adjuvants to support these new applications. In this paper, we used pharmaceutical grade mineral oil and sorbitan monooleate to develop a new oil adjuvant formula, NH(2) , and investigated its effects on peptide vaccination at both the pre-clinical and clinical levels. The adjuvant effect of NH(2) on peptide-induced cellular immunity in mice was superior to that of Montanide ISA51VG, a commercially available incomplete Freund's adjuvant for clinical use, although no significant difference was observed between the two adjuvants on peptide-induced humoral immunity. The adjuvant effects of NH(2) were also confirmed in a Phase-I clinical trial of peptide vaccines for patients with advanced cancers. These results suggest that NH(2) is a suitable adjuvant for peptide vaccination, particularly for cancer vaccines (Phase-I clinical trial of pan-HLA type personalized peptide vaccine for advanced cancer patients, UMIN clinical trial registry number: UMIN 000000619).

A new insight into hepatitis C vaccine development

Chronic hepatitis C virus (HCV) infection remains a serious burden to public health worldwide. Currently, HCV-infected patients could undergo antiviral therapy by giving pegylated IFN-α with ribavirin. However, this therapy is only effective in around 50% of patients with HCV genotype 1, which accounts for more than 70% of all HCV infection, and it is not well tolerated for most patients. Moreover, there is no vaccine available. The efforts on identifying protective immunity against HCV have progressed recently. Neutralizing antibodies and robust T cell responses including both CD4⁺ and CD8⁺ have been shown to be related to the clearance of HCV, which have shed lights on the potential success of HCV vaccines. There are many vaccines developed and tested before entering clinical trials. Here, we would first discuss strategies of viral immune evasion and correlates of protective host immunity and finally review some prospective vaccine approaches against chronic HCV infection.

Immunization with a DNA vaccine candidate in chronic hepatitis C patients is safe, well tolerated and does not impair immune response induction after anti-hepatitis B vaccination

BACKGROUND

In the present study, we evaluated the safety of CIGB-230, a novel vaccine candidate based on the mixture of a plasmid for DNA immunization, expressing hepatitis C virus (HCV) structural antigens, with a recombinant HCV Core protein.

METHODS

Fifteen HCV chronically-infected volunteers with detectable levels of HCV RNA genotype 1b, who were nonresponders to previous treatment with interferon plus ribavirin, were intramuscularly injected with CIGB-230 on weeks 0, 4, 8, 12, 16 and 20. Individuals were also immunized at weeks 28, 32 and 36 with a recombinant vaccine against hepatitis B. Adverse events were recorded and analyzed. Blood samples were taken every 4 weeks up to month 12 for hematological, biochemical, virological and immunological analysis.

RESULTS

All patients completed the treatment with CIGB-230. Adverse events were only slight (83.6%) or moderate (16.4%). No significant differences in hematological and biochemical parameters, including serum aminotransferases, were detected between the baseline and post-treatment state. Induction of a CD4+ T lymphocyte response against a particular region in HCV E1, spanning amino acids 230-312 in HCV polyprotein, was detected in 42.8% of patients during treatment with CIGB-230. The ability of T cells to proliferate in response to mitogenic stimulation was not weakened. Most individuals (78.6%) were seroprotected after anti-hepatitis B vaccination and 42.8% were hyper-responders (antibody titers > 100 UI/ml). No anti-mitochondrial, anti-nuclear and anti-extractable nuclear antigen antibodies were generated during immunization with CIGB-230.

CONCLUSIONS

Vaccination with CIGB-230 in HCV chronically-infected individuals was safe, well tolerated and did not impair the ability to respond to non-HCV antigens.

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.

Prophylactic and Therapeutic Vaccination against Hepatitis C Virus (HCV): Developments and Future Perspectives

Studies in patients and chimpanzees that spontaneously clear Hepatitis C Virus (HCV) have demonstrated that natural immunity to the virus is induced during primary infections and that this immunity can be cross protective. These discoveries led to optimism regarding prophylactic HCV vaccines and a number of studies in the chimpanzee model have been performed, all of which resulted in modified infections after challenge but did not always prevent persistence of the virus. Therapeutic vaccine strategies have also been pursued in an effort to reduce the costs and side effects associated with anti-viral drug treatment. This review summarizes the studies performed thus far in both patients and chimpanzees for prophylactic and therapeutic vaccination, assesses the progress made and future perspectives.

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.

Enhancement of the expression of HCV core gene does not enhance core-specific immune response in DNA immunization: advantages of the heterologous DNA prime, protein boost immunization regimen

BACKGROUND

Hepatitis C core protein is an attractive target for HCV vaccine aimed to exterminate HCV infected cells. However, although highly immunogenic in natural infection, core appears to have low immunogenicity in experimental settings. We aimed to design an HCV vaccine prototype based on core, and devise immunization regimens that would lead to potent anti-core immune responses which circumvent the immunogenicity limitations earlier observed.

METHODS

Plasmids encoding core with no translation initiation signal (pCMVcore); with Kozak sequence (pCMVcoreKozak); and with HCV IRES (pCMVcoreIRES) were designed and expressed in a variety of eukaryotic cells. Polyproteins corresponding to HCV 1b amino acids (aa) 1-98 and 1-173 were expressed in E. coli. C57BL/6 mice were immunized with four 25-microg doses of pCMVcoreKozak, or pCMV (I). BALB/c mice were immunized with 100 microg of either pCMVcore, or pCMVcoreKozak, or pCMVcoreIRES, or empty pCMV (II). Lastly, BALB/c mice were immunized with 20 microg of core aa 1-98 in prime and boost, or with 100 microg of pCMVcoreKozak in prime and 20 microg of core aa 1-98 in boost (III). Antibody response, [3H]-T-incorporation, and cytokine secretion by core/core peptide-stimulated splenocytes were assessed after each immunization.

RESULTS

Plasmids differed in core-expression capacity: mouse fibroblasts transfected with pCMVcore, pCMVcoreIRES and pCMVcoreKozak expressed 0.22 +/- 0.18, 0.83 +/- 0.5, and 13 +/- 5 ng core per cell, respectively. Single immunization with highly expressing pCMVcoreKozak induced specific IFN-gamma and IL-2, and weak antibody response. Single immunization with plasmids directing low levels of core expression induced similar levels of cytokines, strong T-cell proliferation (pCMVcoreIRES), and antibodies in titer 103(pCMVcore). Boosting with pCMVcoreKozak induced low antibody response, core-specific T-cell proliferation and IFN-gamma secretion that subsided after the 3rd plasmid injection. The latter also led to a decrease in specific IL-2 secretion. The best was the heterologous pCMVcoreKozak prime/protein boost regiment that generated mixed Th1/Th2-cellular response with core-specific antibodies in titer >or= 3 x 10(3).

CONCLUSION

Thus, administration of highly expressed HCV core gene, as one large dose or repeated injections of smaller doses, may suppress core-specific immune response. Instead, the latter is induced by a heterologous DNA prime/protein boost regiment that circumvents the negative effects of intracellular core expression.

Immune-based therapy for chronic hepatitis C

Chronic, persistent HCV infection is a public health issue. It often progresses to life-threatening complications, including liver cirrhosis and hepatocellular carcinoma. The current standard therapy is a combination of pegylated IFN-alpha and ribavirin. This therapy results in a sustained virologic response in only 50% of patients infected with HCV genotype 1 and is often accompanied with substantial side-effects. Therefore, it is imperative to develop novel therapies with higher efficacy and less substantial side-effects. Impaired immune responses to HCV are key features of chronic HCV infection; thus, intervention strategies typically involve boosting the immune responses against HCV. These immune-based therapies for chronic HCV infection include therapeutic vaccines, antagonists of T cell inhibitory factors, anti-HCV neutralizing antibodies, cytokines, and agonists for TLRs. Currently, various types of immune-based therapies are under development that might be used as a monotherapy or in combination with other antiviral drugs for the treatment of chronic HCV infection.

Development of hepatitis C virus vaccines: challenges and progress

Development of an effective vaccine against the hepatitis C virus (HCV) has long been defined as a difficult challenge due to the considerable variability of this RNA virus and the observation that convalescent humans and chimpanzees could be re-infected after re-exposure. On the other hand, progress in the understanding of antiviral immune responses in patients with viral clearance has elucidated key mechanisms playing a role in the control of viral infection. Studies investigating prophylactic vaccine approaches in chimpanzees have confirmed that the induction and maintenance of strong helper and cytotoxic T-cell immune responses against multiple viral epitopes is necessary for protection against viral clearance and chronic infection. A multispecific B-cell response, resulting in rapid induction of cross-neutralizing antibodies may assist cellular responses. Therapeutic vaccine formulations currently being evaluated in clinical trials are facing the fact that the immune system of chronic carriers is impaired and needs the restoration of T-cell functions to enhance their efficacy.

HLA and infectious diseases

Following their discovery in the early 1970s, classical human leukocyte antigen (HLA) loci have been the prototypical candidates for genetic susceptibility to infectious disease. Indeed, the original hypothesis for the extreme variability observed at HLA loci (H-2 in mice) was the major selective pressure from infectious diseases. Now that both the human genome and the molecular basis of innate and acquired immunity are understood in greater detail, do the classical HLA loci still stand out as major genes that determine susceptibility to infectious disease? This review looks afresh at the evidence supporting a role for classical HLA loci in susceptibility to infectious disease, examines the limitations of data reported to date, and discusses current advances in methodology and technology that will potentially lead to greater understanding of their role in infectious diseases in the future.

Immunogenicity of CIGB-230, a therapeutic DNA vaccine preparation, in HCV-chronically infected individuals in a Phase I clinical trial

Hepatitis C virus (HCV) is a worldwide health problem. No vaccine is available against this pathogen and therapeutic treatments currently in use are of limited efficacy. In the present study, the immunogenicity of the therapeutic vaccine candidate CIGB-230, based on the mixture of pIDKE2, a plasmid expressing HCV structural antigens, with a recombinant HCV core protein, Co.120, was evaluated. CIGB-230 was administered by intramuscular injection on weeks 0, 4, 8, 12, 16 and 20 to 15 HCV-chronically infected individuals, non-responders to previous treatment with interferon (IFN) plus ribavirin. Interestingly, following the final immunization, neutralizing antibody responses against heterologous viral pseudoparticles were modified in eight individuals, including six de novo responders. In addition, 73% of vaccinees exhibited specific T cell proliferative response and T cell IFN-gamma secretory response 24 weeks after primary immunization with CIGB-230. Furthermore, 33.3% of individuals developed de novo cellular immune response against HCV core and the number of patients (46.7% at the end of treatment) with cellular immune response against more than one HCV structural antigen increased during vaccination (P = 0.046). In addition, despite persistent detection of HCV RNA, more than 40% percent of vaccinated individuals improved or stabilized liver histology, particularly reducing fibrosis, which correlated with cellular immune response against more than one HCV antigen (P = 0.0053). In conclusion, CIGB-230 is a promising candidate for effective therapeutic interventions based on its ability for enhancing the immune response in HCV chronically infected individuals.

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.