Prospects for prophylactic and therapeutic vaccines against hepatitis C virus

Bioinformatics analysis of multi-epitope peptide vaccines against Hepatitis C virus: a molecular docking study

BACKGROUND

Hepatitis C Virus (HCV) infection is one of the causal agents of liver disease burden. Six multiple antigenic peptides were synthesized including (P315, P412, and P517) plus (P1771, P2121, and P2941) to induce humoral and cellular responses, respectively against HCV infection.

AIM

This paper aimed to employ computational tools to evaluate the efficacy of each peptide individually and to determine the most effective one for better vaccine development and/or immunotherapy.

METHODS

VaxiJen web and AllerTOP servers were used for antigenicity and allergenicity prediction, respectively. The ToxinPred web server was used to investigate the peptide toxicity. Each peptide was docked with its corresponding receptors.

RESULTS

No peptides were expected to be toxic. P315 and P2941 are predicted to have robust antigenic properties, lowest allergenicity, and minimal sOPEP energies. In turn, P315 (derived from gpE1) formed the highest hydrophobic bonds with the BCR and CD81 receptors that will elicit B cell function. P2941 (derived from NS5B) was shown to strongly bind to both CD4 and CD8 receptors that will elicit T cell function.

CONCLUSION

P315 successfully bound to B cell (BCR and CD81) receptors. Also, P2941 is strongly bound to T cell (CD4 and CD8) receptors.

In the era of rapid mRNA-based vaccines: Why is there no effective hepatitis C virus vaccine yet?

Hepatitis C virus (HCV) is responsible for no less than 71 million people chronically infected and is one of the most frequent indications for liver transplantation worldwide. Despite direct-acting antiviral therapies fuel optimism in controlling HCV infections, there are several obstacles regarding treatment accessibility and reinfection continues to remain a possibility. Indeed, the majority of new HCV infections in developed countries occur in people who inject drugs and are more plausible to get reinfected. To achieve global epidemic control of this virus the development of an effective prophylactic or therapeutic vaccine becomes a must. The coronavirus disease 19 (COVID-19) pandemic led to auspicious vaccine development against severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) virus, which has renewed interest on fighting HCV epidemic with vaccination. The aim of this review is to highlight the current situation of HCV vaccine candidates designed to prevent and/or to reduce HCV infectious cases and their complications. We will emphasize on some of the crossroads encountered during vaccine development against this insidious virus, together with some key aspects of HCV immunology which have, so far, hampered the progress in this area. The main focus will be on nucleic acid-based as well as recombinant viral vector-based vaccine candidates as the most novel vaccine approaches, some of which have been recently and successfully employed for SARS-CoV-2 vaccines. Finally, some ideas will be presented on which methods to explore for the design of live-attenuated vaccines against HCV.

Antiviral therapy for the sexually transmitted viruses: recent updates on vaccine development

INTRODUCTION

The sexually transmitted infections (STIs) caused by viruses including human T cell leukemia virus type-1 (HTLV-1), human immunodeficiency virus-1 (HIV-1), human simplex virus-2 (HSV-2), hepatitis C virus (HCV), hepatitis B virus (HBV), and human papillomavirus (HPV) are major public health issues. These infections can cause cancer or result in long-term health problems. Due to high prevalence of STIs, a safe and effective vaccine is required to overcome these fatal viruses.

AREAS COVERED

This review includes a comprehensive overview of the literatures relevant to vaccine development against the sexually transmitted viruses (STVs) using PubMed and Sciencedirect electronic search engines. Herein, we discuss the efforts directed toward development of effective vaccines using different laboratory animal models including mice, guinea pig or non-human primates in preclinical trials, and human in clinical trials with different phases.

EXPERT OPINION

There is no effective FDA approved vaccine against the sexually transmitted viruses (STVs) except for HBV and HPV as prophylactic vaccines. Many attempts are underway to develop vaccines against these viruses. There are several approaches for improving prophylactic or therapeutic vaccines such as heterologous prime/boost immunization, delivery system, administration route, adjuvants, etc. In this line, further studies can be helpful for understanding the immunobiology of STVs in human. Moreover, development of more relevant animal models is a worthy goal to induce effective immune responses in humans.

Broad Spectrum Peptide Vaccine Design Against Hepatitis C Virus

BACKGROUND

Hepatitis C virus (HCV) infection is a global burden. There is no peptide vaccine found as modality to cure the disease is available due to the weak cellular immune response and the limitation to induce humoral immune response.

METHODS

Five predominated HCV subtypes in Indonesia (1a, 1b, 1c, 3a, and 3k) were aligned and the conserved regions were selected. Twenty alleles of class I MHC including HLA-A, HLA-B, and HLAC types were used to predict the potential epitopes by using NetMHCPan and IEDB. Eight alleles of HLA-DRB1, together with a combination of 3 alleles of HLA-DQA1 and 5 alleles of HLA-DQB1 were utilized for Class II MHC epitopes prediction using NetMHCIIPan and IEDB. LBtope and Ig- Pred were used to predict B cells epitopes. Moreover, proteasome analysis was performed by NetCTL and the stability of the epitopes in HLA was calculated using NetMHCStabPan for Class I. All predicted epitopes were analyzed for its antigenicity, toxicity, and stability. Population coverage, molecular docking and molecular dynamics were performed for several best epitopes.

RESULTS

The results showed that two best epitopes from envelop protein, GHRMAWDMMMNWSP (E1) and PALSTGLIHLHQN (E2) were selected as promising B cell and CD8+ T cell inducers. Other two peptides, LGIGTVLDQAETAG and VLVLNPSVAATLGF, taken from NS3 protein were selected as CD4+ T cell inducer.

CONCLUSION

This study suggested the utilization of all four peptides to make a combinational peptide vaccine for in vivo study to prove its ability in inducing secondary response toward HCV.

A Hepatitis C Virus DNA Vaccine Encoding a Secreted, Oligomerized Form of Envelope Proteins Is Highly Immunogenic and Elicits Neutralizing Antibodies in Vaccinated Mice

Hepatitis C virus (HCV) persistently infects approximately 71 million people globally. To prevent infection a vaccine which elicits neutralizing antibodies against the virus envelope proteins (E1/E2) which are required for entry into host cells is desirable. DNA vaccines are cost-effective to manufacture globally and despite recent landmark studies highlighting the therapeutic efficacy of DNA vaccines in humans against cervical cancer, DNA vaccines encoding E1/E2 developed thus far are poorly immunogenic. We now report a novel and highly immunogenic DNA vaccination strategy that incorporates secreted E1 and E2 (sE1 and sE2) into oligomers by fusion with the oligomerization domain of the C4b-binding protein, IMX313P. The FDA approved plasmid, pVax, was used to encode sE1, sE2, or sE1E2 with or without IMX313P, and intradermal prime-boost vaccination studies in BALB/c mice showed that vaccines encoding IMX313P were the most effective in eliciting humoral and cell-mediated immunity against the envelope proteins. Further boosting with recombinant E1E2 proteins but not DNA nor virus-like particles (VLPs) expressing E1E2 increased the immunogenicity of the DNA prime-boost regimen. Nevertheless, the antibodies generated by the homologous DNA prime-boost vaccinations more effectively inhibited the binding of VLPs to target cells and neutralized transduction with HCV pseudoparticles (HCVpp) derived from different genotypes including genotypes 1, 2, 3, 4, 5, and 6. This report provides the first evidence that IMX313P can be used as an adjuvant for E1/E2-based DNA vaccines and represents a translatable approach for the development of a HCV DNA vaccine.

Role of the E2 Hypervariable Region (HVR1) in the Immunogenicity of a Recombinant Hepatitis C Virus Vaccine

Current evidence supports a protective role for virus-neutralizing antibodies in immunity against hepatitis C virus (HCV) infection. Many cross-neutralizing monoclonal antibodies have been identified. These antibodies have been shown to provide protection or to clear infection in animal models. Previous clinical trials have shown that a gpE1/gpE2 vaccine can induce antibodies that neutralize the in vitro infectivity of all the major cell culture-derived HCV (HCVcc) genotypes around the world. However, cross-neutralization appeared to favor certain genotypes, with significant but lower neutralization against others. HCV may employ epitope masking to avoid antibody-mediated neutralization. Hypervariable region 1 (HVR1) at the amino terminus of glycoprotein E2 has been shown to restrict access to many neutralizing antibodies. Consistent with this, other groups have reported that recombinant viruses lacking HVR1 are hypersensitive to neutralization. It has been proposed that gpE1/gpE2 lacking this domain could be a better vaccine antigen to induce broadly neutralizing antibodies. In this study, we examined the immunogenicity of recombinant gpE1/gpE2 lacking HVR1 (ΔHVR1). Our results indicate that wild-type (WT) and ΔHVR1 gpE1/gpE2 antigens induced antibodies targeting many well-characterized cross-genotype-neutralizing epitopes. However, while the WT gpE1/gpE2 vaccine can induce cross-genotype protection against various genotypes of HCVcc and/or HCV-pseudotyped virus (HCVpp), antisera from ΔHVR1 gpE1/gpE2-immunized animals exhibited either reduced homologous neutralization activity compared to that of the WT or heterologous neutralization activity similar to that of the WT. These data suggest that ΔHVR1 gpE1/gpE2 is not a superior vaccine antigen. Based on previously reported chimpanzee protection data using WT gpE1/gpE2 and our current findings, we are preparing a combination vaccine including wild-type recombinant gpE1/gpE2 for clinical testing in the future.

IMPORTANCE An HCV vaccine is an unmet medical need. Current evidence suggests that neutralizing antibodies play an important role in virus clearance, along with cellular immune responses. Previous clinical data showed that gpE1/gpE2 can effectively induce cross-neutralizing antibodies, although they favor certain genotypes. HCV employs HVR1 within gpE2 to evade host immune control. It has been hypothesized that the removal of this domain would improve the production of cross-neutralizing antibodies. In this study, we compared the immunogenicities of WT and ΔHVR1 gpE1/gpE2 antigens as vaccine candidates. Our results indicate that the ΔHVR1 gpE1/gpE2 antigen confers no advantages in the neutralization of HCV compared with the WT antigen. Previously, we showed that this WT antigen remains the only vaccine candidate to protect chimpanzees from chronic infection, contains multiple cross-neutralizing epitopes, and is well tolerated and immunogenic in humans. The current data support the further clinical development of this vaccine antigen component.

Qualitative differences in cellular immunogenicity elicited by hepatitis C virus T-Cell vaccines employing prime-boost regimens

T-cell based vaccines have been considered as attractive candidates for prevention of hepatitis C virus (HCV) infections. In this study we compared the magnitude and phenotypic characteristics of CD8+ T-cells induced by three commonly used viral vectors, Adenovirus-5 (Ad5), Vaccinia virus (VV) and Modified Vaccinia Ankara (MVA) expressing the HCV NS3/4A protein. C57/BL6 mice were primed with DNA expressing NS3/4A and boosted with each of the viral vectors in individual groups of mice. We then tracked the vaccine-induced CD8+ T-cell responses using pentamer binding and cytokine production analysis. Overall, our data indicate that the memory cells induced by Ad5 were inferior to those induced by VV or MVA. We found that Ad5 boosting resulted in rapid expansion and significantly higher frequencies of NS3-specific T-cells compared to VV and MVA boosting. However, the functional profiles, assessed through analysis of the memory cell marker CD127 and the anti-apoptotic molecule Bcl-2 in the blood, spleen, and liver; and measurements of interferon-gamma, tumor necrosis factor-alpha, and interleukin-2 production indicated significantly lower frequencies of long-lived memory T-cells following Ad5 boosting compared to VV and MVA. This same set of analyses suggested that the memory cells induced following boosting with MVA were superior to those induced by both Ad5 and VV. This superiority of the MVA-induced CD8+ T-cells was confirmed following surrogate challenge of mice with a recombinant mouse herpes virus expressing the HCV NS3 protein. Higher levels of NS3-specific CD8+ T-cells displaying the functional markers CD69, Ki67 and Granzyme B were found in the spleens of mice boosted with MVA compared to VV and Ad5, both alone and in combination. These data suggest that MVA may be a more successful viral vector for induction of effective CD8+ T-cell responses against hepatitis C virus.

Hepatitis C virus E2 protein encapsulation into poly d, l-lactic-co-glycolide microspheres could induce mice cytotoxic T-cell response

Hepatitis C virus (HCV) is known to cause hepatitis and hepatocellular carcinoma. E2 envelope glycoprotein of HCV type (HCV-E2) has been reported to bind human host cells and is a major target for developing anti-HCV vaccines. However, the therapeutic vaccine for infected patients still needs further development. The vaccine aims to provide cytotoxic T-cells to eliminate infected cells and hepatocellular carcinoma. Currently, there is no effective HCV therapeutic vaccine because most chronically infected patients rarely generate cytotoxic T-cells, even though they have high levels of neutralizing antibodies. Therefore, the adjuvant must be applied to enhance the efficacy of the therapeutic vaccine. In this study, we constructed HCV1b-E2 recombinant protein, a truncated form of peptide, to combine with an effective vaccine adjuvant and delivery system by using poly d,l-lactic-co-glycolide (PLGA) microspheres. HCV1b-E2 protein was effectively encapsulated into PLGA microspheres (HCV1b-E2-PLGA) as a strategy to deliver an insoluble form of HCV1b-E2 protein. The size and shape of PLGA microspheres were generated properly to carry an insoluble form of viral peptide in vivo. The encapsulated viral protein was slowly and continuously released from PLGA microspheres, which indicated the property of the adjuvant. HCV1b-E2-PLGA can trigger a cell-mediated immune response by inducing an expression of mice CD8⁺ T-cells. Our results demonstrated that HCV1b-E2-PLGA-immunized mice have a significantly increased CD8⁺ T-cell number, whereas HCV1b-E2-immunized mice have a lower number of CD8⁺ T-cells. Moreover, HCV1b-E2-PLGA could induce a specific antibody to viral protein, and the immune cells could secrete IFN-γ, which is a significant cytokine for viral response. Thus, HCV1b-E2-PLGA is shown to have adjuvant property and efficacy in the murine model, which is a good strategy to develop HCV prophylactic and therapeutic vaccines.

The history of hepatitis C virus (HCV): Basic research reveals unique features in phylogeny, evolution and the viral life cycle with new perspectives for epidemic control

The discovery of hepatitis C virus (HCV) in 1989 permitted basic research to unravel critical components of a complex life cycle for this important human pathogen. HCV is a highly divergent group of viruses classified in 7 major genotypes and a great number of subtypes, and circulating in infected individuals as a continuously evolving quasispecies destined to escape host immune responses and applied antivirals. Despite the inability to culture patient viruses directly in the laboratory, efforts to define the infectious genome of HCV resulted in development of experimental recombinant in vivo and in vitro systems, including replicons and infectious cultures in human hepatoma cell lines. And HCV has become a model virus defining new paradigms in virology, immunology and biology. For example, HCV research discovered that a virus could be completely dependent on microRNA for its replication since microRNA-122 is critical for the HCV life cycle. A number of other host molecules critical for HCV entry and replication have been identified. Thus, basic HCV research revealed important molecules for development of host targeting agents (HTA). The identification and characterization of HCV encoded proteins and their functional units contributed to the development of highly effective direct acting antivirals (DAA) against the NS3 protease, NS5A and the NS5B polymerase. In combination, these inhibitors have since 2014 permitted interferon-free therapy with cure rates above 90% among patients with chronic HCV infection; however, viral resistance represents a challenge. Worldwide control of HCV will most likely require the development of a prophylactic vaccine, and numerous candidates have been pursued. Research characterizing features critical for antibody-based virus neutralization and T cell based virus elimination from infected cells is essential for this effort. If the world community promotes an ambitious approach by applying current DAA broadly, continues to develop alternative viral- and host- targeted antivirals to combat resistant variants, and invests in the development of a vaccine, it would be possible to eradicate HCV. This would prevent about 500 thousand deaths annually. However, given the nature of HCV, the millions of new infections annually, a high chronicity rate, and with over 150 million individuals with chronic infection (which are frequently unidentified), this effort remains a major challenge for basic researchers, clinicians and communities.

Hepatitis C virus vaccine candidates inducing protective neutralizing antibodies

INTRODUCTION

With more than 150 million chronically infected people, hepatitis C virus (HCV) remains a substantial global health burden. Direct-acting antivirals have dramatically improved viral cure. However, limited access to therapy, late stage detection of infection and re-infection following cure illustrate the need for a vaccine for global control of infection. Vaccines with induction of neutralizing antibodies (nAbs) have been shown to protect successfully against infections by multiple viruses and are currently developed for HCV. Areas covered: Here we review the progress towards the development of vaccines aiming to confer protection against chronic HCV infection by inducing broadly nAbs. The understanding or viral immune evasion in infected patients, the development of novel model systems and the recent structural characterization of viral envelope glycoprotein E2 has markedly advanced our understanding of the molecular mechanisms of virus neutralization with the concomitant development of several vaccine candidates. Expert commentary: While HCV vaccine development remains challenged by the high viral diversity and immune evasion, marked progress in HCV research has advanced vaccine design. Several vaccine candidates have shown robust induction of nAbs in animal models and humans. Randomized clinical trials are the next step to assess their clinical efficacy for protection against chronic infection.

Protective T Cell and Antibody Immune Responses against Hepatitis C Virus Achieved Using a Biopolyester-Bead-Based Vaccine Delivery System

Hepatitis C virus (HCV) infection is a major worldwide problem. Chronic hepatitis C is recognized as one of the major causes of cirrhosis, hepatocellular carcinoma, and liver failure. Although new, directly acting antiviral therapies are suggested to overcome the low efficacy and adverse effects observed for the current standard of treatment, an effective vaccine would be the only way to certainly eradicate HCV infection. Recently, polyhydroxybutyrate beads produced by engineered Escherichia coli showed efficacy as a vaccine delivery system. Here, an endotoxin-free E. coli strain (ClearColi) was engineered to produce polyhydroxybutyrate beads displaying the core antigen on their surface (Beads-Core) and their immunogenicity was evaluated in BALB/c mice. Immunization with Beads-Core induced gamma interferon (IFN-γ) secretion and a functional T cell immune response against the HCV Core protein. With the aim to target broad T and B cell determinants described for HCV, Beads-Core mixed with HCV E1, E2, and NS3 recombinant proteins was also evaluated in BALB/c mice. Remarkably, only three immunization with Beads-Core+CoE1E2NS3/Alum (a mixture of 0.1 μg Co.120, 16.7 μg E1.340, 16.7 μg E2.680, and 10 μg NS3 adjuvanted in aluminum hydroxide [Alum]) induced a potent antibody response against E1 and E2 and a broad IFN-γ secretion and T cell response against Core and all coadministered antigens. This immunological response mediated protective immunity to viremia as assessed in a viral surrogate challenge model. Overall, it was shown that engineered biopolyester beads displaying foreign antigens are immunogenic and might present a particulate delivery system suitable for vaccination against HCV.

[Way to the peptide vaccine against hepatitis C]

In order to surpass the problem of genetic variability of hepatitis C virus envelope proteins during vaccine development, we used the so-called "reverse vaccinology"approach--"from genome to vaccine". Database of HCV protein sequences was designed, viral genome analysis was performed, and several highly conserved sites were revealed in HCV envelope proteins in the framework of this approach. These sites demonstrated low antigenic activity in full-size proteins and HCV virions: antibodies against these sites were not found in all hepatitis C patients. However, two sites, which contained a wide set of potential T-helper epitope motifs, were revealed among these highly conserved ones. We constructed and prepared by solid-phase peptide synthesis several artificial peptide constructs composed of two linker-connected highly conserved HCV envelope E2 protein sites; one of these sites contained a set of T-helper epitope motifs. Experiments on laboratory animals demonstrated that the developed peptide constructs manifested immunogenicity compared with one of protein molecules and were able to raise antibodies, which specifically bound HCV envelope proteins. We succeeded in obtaining antibodies reactive with HCV from hepatitis C patient plasma upon the immunization with some constructs. An original preparation of a peptide vaccine against hepatitis C is under development on the basis of these peptide constructs.

Antibodies to an interfering epitope in hepatitis C virus E2 can mask vaccine-induced neutralizing activity

Hepatitis C virus (HCV) neutralization occurring at the E2 region 412-426 (EP-I) could be enhanced when antibodies directed specifically to the E2 region 434-446 (EP-II) were removed from serum samples of persistently infected patients and vaccinated chimpanzees, a phenomenon of so-called antibody interference. Here, we show that this type of interference can be observed in individuals after immunization with recombinant E1E2 proteins. One hundred twelve blinded serum samples from a phase I, placebo-controlled, dose escalation trial using recombinant HCV E1E2 with MF59C.1 adjuvant in healthy HCV-negative adults were tested in enzyme-linked immunosorbent assay for binding reactivity to peptides representing the E2 regions 412-426 (EP-I) and 434-446 (EP-II). All samples were subsequently tested for neutralizing activity using cell-culture HCV 1a(H77)/2a chimera, HCV pseudotype particles (HCVpp) H77, and HCVpp HCV-1 after treatment to remove EP-II-specific antibodies or mock treatment with a control peptide. Among the 112 serum samples, we found 22 double positive (EP-I and EP-II), 6 EP-II positive only, 14 EP-I positive only, and 70 double negative. Depleting EP-II antibodies from double-positive serum samples increased 50% inhibitory dose (ID50) neutralizing antibody titers (up to 4.9-fold) in up to 72% of samples (P ≤ 0.0005), contrasting with ID50 neutralization titer increases in 2 of 70 double-negative samples (2.9%; P > 0.5). In addition, EP-I-specific antibody levels in serum samples showed a significant correlation with ID50 neutralization titers when EP-II antibodies were removed (P < 0.0003).

CONCLUSION

These data show that antibodies to the region 434-446 are induced during immunization of individuals with recombinant E1E2 proteins, and that these antibodies can mask effective neutralizing activity from EP-I-specific antibodies. Elicitation of EP-II-specific antibodies with interfering capacity should be avoided in producing an effective cross-neutralizing vaccine aimed at the HCV envelope proteins.

Agent-Based Model Forecasts Aging of the Population of People Who Inject Drugs in Metropolitan Chicago and Changing Prevalence of Hepatitis C Infections

People who inject drugs (PWID) are at high risk for blood-borne pathogens transmitted during the sharing of contaminated injection equipment, particularly hepatitis C virus (HCV). HCV prevalence is influenced by a complex interplay of drug-use behaviors, social networks, and geography, as well as the availability of interventions, such as needle exchange programs. To adequately address this complexity in HCV epidemic forecasting, we have developed a computational model, the Agent-based Pathogen Kinetics model (APK). APK simulates the PWID population in metropolitan Chicago, including the social interactions that result in HCV infection. We used multiple empirical data sources on Chicago PWID to build a spatial distribution of an in silico PWID population and modeled networks among the PWID by considering the geography of the city and its suburbs. APK was validated against 2012 empirical data (the latest available) and shown to agree with network and epidemiological surveys to within 1%. For the period 2010–2020, APK forecasts a decline in HCV prevalence of 0.8% per year from 44(±2)% to 36(±5)%, although some sub-populations would continue to have relatively high prevalence, including Non-Hispanic Blacks, 48(±5)%. The rate of decline will be lowest in Non-Hispanic Whites and we find, in a reversal of historical trends, that incidence among non-Hispanic Whites would exceed incidence among Non-Hispanic Blacks (0.66 per 100 per years vs 0.17 per 100 person years). APK also forecasts an increase in PWID mean age from 35(±1) to 40(±2) with a corresponding increase from 59(±2)% to 80(±6)% in the proportion of the population >30 years old. Our studies highlight the importance of analyzing subpopulations in disease predictions, the utility of computer simulation for analyzing demographic and health trends among PWID and serve as a tool for guiding intervention and prevention strategies in Chicago, and other major cities.

Mathematical Modeling of Hepatitis C Prevalence Reduction with Antiviral Treatment Scale-Up in Persons Who Inject Drugs in Metropolitan Chicago

BACKGROUND/AIM

New direct-acting antivirals (DAAs) provide an opportunity to combat hepatitis C virus (HCV) infection in persons who inject drugs (PWID). Here we use a mathematical model to predict the impact of a DAA-treatment scale-up on HCV prevalence among PWID and the estimated cost in metropolitan Chicago.

METHODS

To estimate the HCV antibody and HCV-RNA (chronic infection) prevalence among the metropolitan Chicago PWID population, we used empirical data from three large epidemiological studies. Cost of DAAs is assumed $50,000 per person.

RESULTS

Approximately 32,000 PWID reside in metropolitan Chicago with an estimated HCV-RNA prevalence of 47% or 15,040 cases. Approximately 22,000 PWID (69% of the total PWID population) attend harm reduction (HR) programs, such as syringe exchange programs, and have an estimated HCV-RNA prevalence of 30%. There are about 11,000 young PWID (<30 years old) with an estimated HCV-RNA prevalence of 10% (PWID in these two subpopulations overlap). The model suggests that the following treatment scale-up is needed to reduce the baseline HCV-RNA prevalence by one-half over 10 years of treatment [cost per year, min-max in millions]: 35 per 1,000 [$50-$77] in the overall PWID population, 19 per 1,000 [$20-$26] for persons in HR programs, and 5 per 1,000 [$3-$4] for young PWID.

CONCLUSIONS

Treatment scale-up could dramatically reduce the prevalence of chronic HCV infection among PWID in Chicago, who are the main reservoir for on-going HCV transmission. Focusing treatment on PWID attending HR programs and/or young PWID could have a significant impact on HCV prevalence in these subpopulations at an attainable cost.

Approaching rational epitope vaccine design for hepatitis C virus with meta-server and multivalent scaffolding

Development of a prophylactic vaccine against hepatitis C virus (HCV) has been hampered by the extraordinary viral diversity and the poor host immune response. Scaffolding, by grafting an epitope onto a heterologous protein scaffold, offers a possible solution to epitope vaccine design. In this study, we designed and characterized epitope vaccine antigens for the antigenic sites of HCV envelope glycoproteins E1 (residues 314–324) and E2 (residues 412–423), for which neutralizing antibody-bound structures are available. We first combined six structural alignment algorithms in a “scaffolding meta-server” to search for diverse scaffolds that can structurally accommodate the HCV epitopes. For each antigenic site, ten scaffolds were selected for computational design, and the resulting epitope scaffolds were analyzed using structure-scoring functions and molecular dynamics simulation. We experimentally confirmed that three E1 and five E2 epitope scaffolds bound to their respective neutralizing antibodies, but with different kinetics. We then investigated a “multivalent scaffolding” approach by displaying 24 copies of an epitope scaffold on a self-assembling nanoparticle, which markedly increased the avidity of antibody binding. Our study thus demonstrates the utility of a multi-scale scaffolding strategy in epitope vaccine design and provides promising HCV immunogens for further assessment in vivo.

Expression, Purification and Immunogenic Description of a Hepatitis C Virus Recombinant CoreE1E2 Protein Expressed by Yeast Pichia pastoris

Background:

Gradual development of a useful vaccine can be the main point in the control and eradication of Hepatitis C virus (HCV) infection. Hepatitis C Virus envelope glycoproteins are considered as the main HCV vaccine candidate.

Objectives:

In this study, the Pichia pastoris expression system was used to express a recombinant HCV CoreE1E2 protein, which consists of Core (269 nt-841nt) E1 (842 nt-1417nt) and E2 (1418 nt-2506nt).

Materials and Methods:

By a codon optimization technique based on the P. pastoris expression system, we could increase the rate of recombinant proteins. Moreover, the purified protein can efficiently induce anti-CoreE1E2 antibodies in rabbits, and also by developing a homemade Enzyme-Linked ELISA kit we can detect antibody of HCV Iranian patients with genotype 1a.

Results:

In our study, the virus-like particle of rCoreE1E2 with 70 nm size, was shown by Electron microscopy and proved the self-assembly in vitro in a yeast expression system.

Conclusions:

These findings of the present study indicate that the recombinant CoreE1E2 glycoprotein is effective in inducing neutralizing antibodies, and is an influential HCV vaccine candidate.

Recombinant adenoviral vector expressing HCV NS4 induces protective immune responses in a mouse model of Vaccinia-HCV virus infection: a dose and route conundrum

Hepatitis C virus (HCV) leads to chronic infection in the majority of infected patients presumably due to failure or inefficiency of the immune responses generated. Both antibody and cellular immune responses have been suggested to be important in viral clearance. Non-replicative adenoviral vectors expressing antigens of interest are considered as attractive vaccine vectors for a number of pathogens. In this study, we sought to evaluate cellular and humoral immune responses against HCV NS4 protein using recombinant adenovirus as a vaccine vector expressing NS4 antigen. We have also measured the effect of antigen doses and routes of immunization on the quality and extent of the immune responses, especially their role in viral load reduction, in a recombinant Vaccinia-HCV (Vac-HCV) infection mouse model. Our results show that an optimum dose of adenovirus vector (2×10(7)pfu/mouse) administered intramuscularly (i.m.) induces high T cell proliferation, granzyme B-expressing CD8(+) T cells, pro-inflammatory cytokines such as IFN-γ, TNF-α, IL-2 and IL-6, and antibody responses that can significantly reduce the Vac-HCV viral load in the ovaries of female C57BL/6 mice. Our results demonstrate that recombinant adenovirus vector can induce both humoral and cellular protective immunity against HCV-NS4 antigen, and that immunity is intricately controlled by route and dose of immunizing vector.

Murine models of hepatitis C: what can we look forward to?

The study of interactions between hepatitis C virus (HCV) with its mammalian host, along with the development of more effective therapeutics and vaccines has been delayed by the lack of a suitable small animal model. HCV readily infects only humans and chimpanzees, which poses logistic, economic and ethical challenges with analyzing HCV infection in vivo. Progress has been made in understanding the determinants that dictate HCV's narrow host range providing a blueprint for constructing a mouse model with inheritable susceptibility to HCV infection. Indeed, genetically humanized mice were generated that support viral uptake, replication and production of infectious virions--albeit at low levels. These efforts are complemented with attempts to select for viral variants that are inherently more capable of replicating in non-human species. In parallel, engraftment of relevant human tissues into improved xenorecipients is being continuously refined. Incorporating advances in stem-cell-biology and tissue engineering may allow the generation of patient-specific humanized mice. Construction of such mouse "avatars" may allow analyzing functionally patient-specific differences with respect to susceptibility to infection, disease progression and responses to treatment. In this review, we discuss the three, before mentioned approaches to overcome current species barriers and generate a small animal model for HCV infection, i.e. genetic modification of mice to increase their susceptibility to the virus; genetic modification of HCV, to increase its pathogenicity for mice; and the introduction of human liver and immune cells into immunodeficient mice, to create "humanized" mice. Although in the foreseeable future there will not be a single model that perfectly mimics the natural course of HCV in humans there is reason for optimism. The spectrum of murine animal models for hepatitis C provides a broad arsenal for analyzing the disease. These models may play an important role by prioritizing vaccine candidates and possibly refining combination anti-viral drug therapies. This article forms part of a symposium in Anti-viral Research on "Hepatitis C: next steps toward global eradication."

Virus infection and human cancer: an overview

It is now estimated that approximately 10 % of worldwide cancers are attributable to viral infection, with the vast majority (>85 %) occurring in the developing world. Oncogenic viruses include various classes of DNA and RNA viruses and induce cancer by a variety of mechanisms. A unifying theme is that cancer develops in a minority of infected individuals and only after chronic infection of many years duration. The viruses associated with the greatest number of cancer cases are the human papillomaviruses (HPVs), which cause cervical cancer and several other epithelial malignancies, and the hepatitis viruses HBV and HCV, which are responsible for the majority of hepatocellular cancer. Other oncoviruses include Epstein-Barr virus (EBV), Kaposi's sarcoma-associated herpes virus (KSHV), human T-cell leukemia virus (HTLV-I), and Merkel cell polyomavirus (MCPyV). Identification of the infectious cause has led to several interventions that may reduce the risk of developing these tumors. These include preventive vaccines against HBV and HPV, HPV-based testing for cervical cancer screening, anti-virals for the treatment of chronic HBV and HCV infection, and screening the blood supply for the presence of HBV and HCV. Successful efforts to identify additional oncogenic viruses in human cancer may lead to further insight into etiology and pathogenesis as well as to new approaches for therapeutic and prophylactic intervention.

Hepatitis C virus: an overview for dental health care providers

BACKGROUND

and Overview. Changes in the science of hepatitis C virus (HCV) infection and transmission in a private dental practice provide an opportunity to update dental health care providers about this pathogen. The authors' aims in this review were to create awareness of health care- associated transmission of hepatitis C and provide an update on the changes in testing and treatment. The authors include data from population-based epidemiologic surveys, clinical practice guidelines, surveillance reports and practice protocols.

RESULTS

In the United States, the elevated prevalence of chronic HCV infection among baby boomers-people born during the period from 1945 through 1965-led the Centers for Disease Control and Prevention to release new national screening guidelines. The authors summarize information about the natural history and epidemiology of hepatitis C and describe the new guidelines and novel treatment options. In addition, the authors provide an overview of how outbreaks of health care-associated HCV are detected and prevented. Practical Implications. Because dental health care professionals likely will treat people with current infection, education in the current science of HCV infection is useful.

Emerging concepts in immunity to hepatitis C virus infection

Since the discovery of hepatitis C virus (HCV) by molecular cloning almost a quarter of a century ago, unprecedented at the time because the virus had never been grown in cell culture or detected serologically, there have been impressive strides in many facets of our understanding of the natural history of the disease, the viral life cycle, the pathogenesis, and antiviral therapy. It is apparent that the virus has developed multiple strategies to evade immune surveillance and eradication. This Review covers what we currently understand of the temporal and spatial immunological changes within the human innate and adaptive host immune responses that ultimately determine the outcomes of HCV infection.

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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Recombinant Nonstructural 3 Protein, rNS3, of Hepatitis C Virus Along With Recombinant GP96 Induce IL-12, TNFα and α5integrin Expression in Antigen Presenting Cells

BACKGROUND

Hepatitis C virus (HCV) infection is the main cause of chronic liver disease and to date there has been no vaccine development to prevent this infection. Among non-structural HCV proteins, NS3 protein is an excellent goal for a therapeutic vaccine, due to its large size and less variation in conserved regions. The immunogenic properties of heat shock proteins (HSPs) for instance GP96 have prompted investigations into their function as strong adjuvant to improve innate and adaptive immunity.

OBJECTIVES

The aim of this study was to examine additive effects of recombinant GP96 (rGP96) fragments accompanied by rNS3 on expression levels of α5integrin and pro-inflammatory cytokines, IL-12 and TNFα, in Antigen Presenting Cells (APCs).

MATERIALS AND METHODS

Recombinant viral proteins (rNS3 and rRGD-NS3), N-terminal and C-terminal fragments of GP96 were produced and purified from E. coli in order to treat the cells; mouse spleen Dendritic Cells (DCs) and THP-1 macrophages.

RESULTS

Our results showed that rNT-GP96 alone significantly increases the expression level of IL-12, TNFα and α5integrin in THP-1 macrophages and DCs, while IL-12 and TNFα expression levels were unaffected by either rNS3 or rRGD-NS3. Interestingly, the co-addition of these recombinant proteins with rNT-GP96 increased IL-12, TNFα and α5integrin expression. Pearson Correlation showed a direct association between α5integrin with IL-12 and TNF-α expression.

CONCLUSIONS

we have highlighted the role of rNS3 plus rNT-GP96 mediated by α5integrin in producing IL-12 and TNFα. It can be suggested that rNT-GP96 could enhance immunity characteristic of rNS3 protein via production of pro-inflammatory cytokines.

Cell-cell contact-mediated hepatitis C virus (HCV) transfer, productive infection, and replication and their requirement for HCV receptors

Hepatitis C virus (HCV) infection is believed to begin with interactions between cell-free HCV and cell receptors that include CD81, scavenger receptor B1 (SR-B1), claudin-1 (CLDN1), and occludin (OCLN). In this study, we have demonstrated that HCV spreading from infected hepatocytes to uninfected hepatocytes leads to the transfer of HCV and the formation of infection foci and is cell density dependent. This cell-cell contact-mediated (CCCM) HCV transfer occurs readily and requires all these known HCV receptors and an intact actin cytoskeleton. With a fluorescently labeled replication-competent HCV system, the CCCM transfer process was further dissected by live-cell imaging into four steps: donor cell-target cell contact, formation of viral puncta-target cell conjugation, transfer of viral puncta, and posttransfer. Importantly, the CCCM HCV transfer leads to productive infection of target cells. Taken together, these results show that CCCM HCV transfer constitutes an important and effective route for HCV infection and dissemination. These findings will aid in the development of new and novel strategies for preventing and treating HCV infection.

A hepatitis C virus (HCV) vaccine comprising envelope glycoproteins gpE1/gpE2 derived from a single isolate elicits broad cross-genotype neutralizing antibodies in humans

Although a cure for HCV is on the near horizon, emerging drug cocktails will be expensive, associated with side-effects and resistance making a global vaccine an urgent priority given the estimated high incidence of infection around the world. Due to the highly heterogeneous nature of HCV, an effective HCV vaccine which could elicit broadly cross-neutralizing antibodies has represented a major challenge. In this study, we tested for the presence of cross-neutralizing antibodies in human volunteers who were immunized with recombinant glycoproteins gpE1/gpE2 derived from a single HCV strain (HCV1 of genotype 1a). Cross neutralization was tested in Huh-7.5 human hepatoma cell cultures using infectious recombinant HCV (HCVcc) expressing structural proteins of heterologous HCV strains from all known major genotypes, 1–7. Vaccination induced significant neutralizing antibodies against heterologous HCV genotype 1a virus which represents the most common genotype in North America. Of the 16 vaccinees tested, 3 were selected on the basis of strong 1a virus neutralization for testing of broad cross-neutralizing responses. At least 1 vaccinee was shown to elicit broad cross-neutralization against all HCV genotypes. Although observed in only a minority of vaccinees, our results prove the key concept that a vaccine derived from a single strain of HCV can elicit broad cross-neutralizing antibodies against all known major genotypes of HCV and provide considerable encouragement for the further development of a human vaccine against this common, global pathogen.

Hepatitis C virus vaccines--progress and perspectives

Approximately 170 million individuals, representing 3% of the global population, are infected with hepatitis C virus (HCV). Whereas strategies for antiviral therapies have markedly improved resulting in clinical licensing of direct-acting antivirals, the development of vaccines has been hampered by the high genetic variability of the virus as well as by the lack of suitable animal models for proof-of-concept studies. Nevertheless, there are several promising vaccine candidates in preclinical and clinical development. After a brief summary of the molecular virology and immunology relevant to vaccine development, this review explains the model systems used for preclinical vaccine development, and highlights examples for most recently developed HCV vaccine candidates.

Prospects for prophylactic hepatitis C vaccines based on virus-like particles

Given the global prevalence and long-term complications of chronic hepatitis C virus (HCV) infection, HCV constitutes one of the greatest challenges to human health of this decade. Considerable efforts have focused on the development of new effective treatments, but about three to four million individuals become infected each year, adding to the world reservoir of HCV infection. The development of a prophylactic vaccine against hepatitis C virus has thus become an important medical priority. Only a few vaccine candidates have progressed to the clinical phase, and published data on both the efficacy and safety of these vaccines are limited, due to many scientific, logistic and bioethic challenges. Fortunately, new innovative vaccine formulations, modes of vaccination and delivery technologies have been developed in recent years. Several preclinical trials of virus-like particle (VLP)-based vaccination strategies are currently underway and have already generated very promising results. In this commentary, we consider the current state of prophylactic HCV vaccines, the hurdles to be overcome in the future and the various VLP-based vaccination approaches currently being developed.

Mouse models for liver cancer

Hepatocellular carcinoma (HCC), the most common form of primary liver cancer is the third leading cause of cancer-related cell death in human and the fifth in women worldwide. The incidence of HCC is increasing despite progress in identifying risk factors, understanding disease etiology and developing anti-viral strategies. Therapeutic options are limited and survival after diagnosis is poor. Therefore, better preventive, diagnostic and therapeutic tools are urgently needed, in particular given the increased contribution from systemic metabolic disease to HCC incidence worldwide. In the last three decades, technological advances have facilitated the generation of genetically engineered mouse models (GEMMs) to mimic the alterations frequently observed in human cancers or to conduct intervention studies and assess the relevance of candidate gene networks in tumor establishment, progression and maintenance. Because these studies allow molecular and cellular manipulations impossible to perform in patients, GEMMs have improved our understanding of this complex disease and represent a source of great potential for mechanism-based therapy development. In this review, we provide an overview of the current state of HCC modeling in the mouse, highlighting successes, current challenges and future opportunities.

Host-targeting agents for prevention and treatment of chronic hepatitis C - perspectives and challenges

Hepatitis C virus (HCV) infection is a major cause of chronic liver disease and hepatocellular carcinoma worldwide. Furthermore, HCV-induced liver disease is a major indication of liver transplantation. In the past years, direct-acting antivirals (DAAs) targeting HCV enzymes have been developed. DAAs increase the virologic response to anti-HCV therapy but may lead to selection of drug-resistant variants and treatment failure. To date, strategies to prevent HCV infection are still lacking and antiviral therapy in immunocompromised patients, patients with advanced liver disease and HIV/HCV-co-infection remains limited. Alternative or complementary approaches addressing the limitations of current antiviral therapies are to boost the host's innate immunity or interfere with host factors required for pathogenesis. Host-targeting agents (HTAs) provide an interesting perspective for novel antiviral strategies against viral hepatitis since they have (i) a high genetic barrier to resistance, (ii) a pan-genotypic antiviral activity, and (iii) complementary mechanisms of action to DAAs and might therefore act in a synergistic manner with current standard of care or DAAs in clinical development. This review highlights HTAs against HCV infection that have potential as novel antivirals and are in preclinical or clinical development.

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.

Viral hepatitis: global goals for vaccination

In countries where hepatitis A is highly endemic, exposure to hepatitis A virus (HAV) is almost universal before the age of 10 years, and large-scale immunization efforts are not required. In contrast, in areas of intermediate endemicity or in transition from high to intermediate endemicity, where transmission occurs primarily from person to person in the general community (often with periodic outbreaks), control of hepatitis A may be achieved through widespread vaccination programmes. Hepatitis B virus (HBV) is one of the world's most widespread infectious agents and the cause of millions of infections each year. Between 500,000 and 700,000 people die each year from chronic infection-related cirrhosis, hepatocellular carcinoma (HCC) or from acute hepatitis B. Hepatitis B vaccine provides protection against infection and its complications including liver cirrhosis and HCC. It is therefore, the first vaccine against a cancer, the first vaccine protecting from a sexually transmitted infection, and the first vaccine against a chronic disease ever licensed. Control and significant reduction in incidence of new HBV infections as well as hepatocellular carcinoma has repeatedly been reported in countries in East Asia (i.e. Taiwan) and Africa (i.e. The Gambia). Two experimental vaccines against hepatitis E have been developed; one of them has been recently licensed but is not yet widely available. Attempts to develop a hepatitis C vaccine were so far unsuccessful.