A prophylactic hepatitis C virus vaccine: a distant peak still worth climbing

Concerted synergy between viral-specific IgG and CD8 + T cells is critical for clearance of an HCV-related rodent hepacivirus

BACKGROUND AND AIMS

Evidence assessing the role of B cells and their antibodies, or lack thereof, in the spontaneous resolution of acute HCV infection is conflicting. Utilization of a strictly hepatotropic, HCV-related rodent hepacivirus (RHV) model circumvents many of the challenges facing the field in characterizing the immunological correlates of dichotomous infection outcomes. This study seeks to elucidate the importance of B cells in the clearance of acute RHV infection.

APPROACH AND RESULTS

µMT mice were infected i.v. with RHV and found to develop chronic infection for over a year. Wild-type (WT) mice depleted of B cells also exhibited persistent viremia that resolved only upon B cell resurgence. The persistent infection developed by B1-8i and AID cre/cre mice revealed that antigen-specific, class-switched B cells or their antibodies were crucial for viral resolution. Virus-specific CD8 + and CD4 + T cells were characterized in these mice using newly developed major histocompatibility complex class I and II tetramers and ex vivo peptide stimulation. Immunoglobulin G (IgG) was purified from the serum of RHV- or lymphocytic choriomeningitis virus Armstrong-infected mice after viral clearance and passively transferred to AID cre/cre recipients, revealing viral clearance only in αRHV IgG recipients. Further, the transfer of αRHV IgG into B cell-depleted recipients also induced viral resolution. This ability of RHV-specific IgG to induce viral clearance was found to require the concomitant presence of CD8 + T cells.

CONCLUSIONS

Our findings demonstrate a cooperative interdependence between immunoglobulins and the T cell compartment that is required for RHV resolution. Thus, HCV vaccine regimens should aim to simultaneously elicit robust HCV-specific antibody and T cell responses for optimal protective efficacy.

Adenoviruses vectored hepatitis C virus vaccine cocktails induce broadly specific immune responses against multi-genotypic HCV in mice

BACKGROUND

Hepatitis C virus (HCV) vaccines are an urgent need to prevent hepatitis C and its further progression of hepatocellular carcinoma. Since the promising T cell based chimpanzee adenovirus and modified vaccinia virus Ankara vectorial HCV vaccines were failed in clinical phase II trial, the vaccine designs to improve protection efficacy in combination of cellular and humoral immunity have been hypothesized against multi-genotypic HCV.

METHODS

Eight HCV vaccine strains were constructed with two novel adenovirus vectors (Sad23L and Ad49L) encoding E1E2 or NS3-5B proteins of HCV genotype (Gt) 1b and 6a isolates, covering 80 % HCV strains prevalent in south China and south-east Asia. Eight HCV vaccine strains were grouped into Sad23L-based vaccine cocktail-1 and Ad49L-based vaccine cocktail-2 for vaccinating mice, respectively.

RESULTS

The immunogenicity of a single dose of 107-1010 PFU HCV individual vaccines was evaluated in mice, showing weak specific antibody to E1 and E2 protein but a dose-dependent T cell response to E1E2/NS3-5B peptides, which could be significantly enhanced by boosting with an alternative vector vaccine carrying homologous antigen. Prime-boost vaccinations with vaccine cocktail-1 and cocktail-2 induced significantly higher cross-reactive antibody and stronger T cell responses to HCV Gt-1b/6a. The high frequency of intrasplenic and intrahepatic NS31629-1637 CD8+ T cell responses were identified, in which the high proportion of TRM and TEM cells might play an important role against HCV infection in liver.

CONCLUSIONS

Prime-boost regimens with HCV vaccine cocktails elicited the broad cross-reactive antibody and robust T cell responses against multi-genotypic HCV in mice.

Clinical performance of the MAGLUMI Anti-HCV (CLIA) Test for detection of hepatitis C virus antibodies

BACKGROUND

Hepatitis C virus (HCV) infection screening and diagnosis are critical to control the hepatitis C epidemic. Testing for anti-HCV antibodies (Ab) in blood samples is the first step to screen people who have been infected with the virus.

OBJECTIVES

To evaluate the performance of the MAGLUMI Anti-HCV (CLIA) Test for detection of HCV antibodies.

STUDY DESIGN

To assess the diagnostic specificity, serum samples from 5053 unselected donors and 205 blood specimens from hospitalized patients were collected. To evaluate the diagnostic sensitivity, 400 positive HCV Ab samples were collected and 30 seroconversion panels were tested. All samples that met the test criteria were tested with the MAGLUMI Anti-HCV (CLIA) Test according to manufacturer's instruction. Results of the MAGLUMI Anti-HCV (CLIA) Test were compared with the Abbott ARCHITECT anti-HCV reference test.

RESULTS

The specificity of the MAGLUMI Anti-HCV (CLIA) Test was 99.75% and 100.00% in blood donor and hospitalized patient samples, respectively. The sensitivity of the Test in HCV Ab positive samples was 100.00%. Seroconversion sensitivity was comparable between the MAGLUMI Anti-HCV (CLIA) Test and the reference assay.

CONCLUSIONS

The performance of the MAGLUMI Anti-HCV (CLIA) Test makes it suited for HCV infection diagnosis.

Recent Insights into the Role of B Cells in Chronic Hepatitis B and C Infections

Chronic viral hepatitis infections, caused by the hepatitis B or C virus, are a major global health problem causing an estimated one million deaths each year. Immunological studies have classically focused on T cells, while B cells have largely been neglected. Emerging evidence, however, highlights a role for B cells in the immunopathogenesis of chronic hepatitis B and C infections. B cell responses appear to be altered across different clinical phases of chronic HBV infection and across stages of disease in chronic HCV infection. These B cell responses show signs of a more activated state with a simultaneous enrichment of phenotypically exhausted atypical memory B cells. Despite the fact that studies show an activating B cell signature in chronic viral hepatitis infection, antibody responses to HBsAg remain impaired in chronic HBV infection, and glycoprotein E2-specific neutralizing antibody responses remain delayed in the acute phase of HCV infection. At the same time, studies have reported that a subset of HBV- and HCV-specific B cells exhibit an exhausted phenotype. This may, at least in part, explain why antibody responses in chronic HBV and HCV patients are suboptimal. Here, we summarize recent findings and discuss upcoming research questions while looking forward to how new single-cell technologies could provide novel insights into the role of B cells in chronic viral hepatitis infections.

Late hepatitis C virus diagnosis among patients with newly diagnosed hepatocellular carcinoma: a case–control study

Background

New direct-acting antiviral therapies have revolutionized hepatitis C virus (HCV) infection therapy. Nonetheless, once liver cirrhosis is established, the risk of hepatocellular carcinoma (HCC) still exists despite virus eradication. Late HCV diagnosis hinders timely access to HCV treatment. Thus, we determined trends and risk factors associated with late HCV among patients with a diagnosis of HCC in Taiwan.

Methods

We conducted a population-based unmatched case–control study. 2008–2018 Claims data were derived from the Taiwan National Health Insurance Research Database. Individuals with an initial occurrence of liver cancer between 2012 and 2018 were included. The late HCV group were referred as individuals who were diagnosed with HCC within 3 years after HCV diagnosis. The control group were referred as individuals who were diagnosed more than 3 years after the index date. We used multivariable logistic models to explore individual- and provider-level risk factors associated with a late HCV diagnosis.

Results

A decreasing trend was observed in the prevalence of late HCV-related HCC diagnosis between 2012 and 2018 in Taiwan. On an individual level, male, elderly patients, patients with diabetes mellitus (DM), and patients with alcohol-related disease had significantly higher risks of late HCV-related HCC diagnosis. On a provider level, patients who were mainly cared for by male physicians, internists and family medicine physicians had a significantly lower risk of late diagnosis.

Conclusions

Elderly and patients who have DM and alcohol related disease should receive early HCV screening. In addition to comorbidities, physician factors also matter. HCV screening strategies shall take these higher risk patients and physician factors into consideration to avoid missing opportunities for early intervention.

Single MHC-I Expression Promotes Virus-Induced Liver Immunopathology

Major histocompatibility complex I (MHC-I) molecules present epitopes on the cellular surface of antigen-presenting cells to prime cytotoxic clusters of differentiation 8 (CD8)⁺ T cells (CTLs), which then identify and eliminate other cells such as virus-infected cells bearing the antigen. Human hepatitis virus cohort studies have previously identified MHC-I molecules as promising predictors of viral clearance. However, the underlying functional significance of these predictions is not fully understood. Here, we show that expression of single MHC-I isomers promotes virus-induced liver immunopathology. Specifically, using the lymphocytic choriomeningitis virus (LCMV) model system, we found MHC-I proteins to be highly up-regulated during infection. Deletion of one of the two MHC-I isomers histocompatibility antigen 2 (H2)-Db or H2-Kb in C57Bl/6 mice resulted in CTL activation recognizing the remaining MHC-I with LCMV epitopes in increased paucity. This increased CTL response resulted in hepatocyte death, increased caspase activation, and severe metabolic changes in liver tissue following infection with LCMV. Moreover, depletion of CTLs abolished LCMV-induced pathology in these mice with resulting viral persistence. In turn, natural killer (NK) cell depletion further increased antiviral CTL immunity and clearance of LCMV even in the presence of a single MHC-I isomer. Conclusion: Our results suggest that uniform MHC-I molecule expression promotes enhanced CTL immunity during viral infection and contributes to increased CTL-mediated liver cell damage that was alleviated by CD8 or NK cell depletion.

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.

Hepatitis C Virus Glycan-Dependent Interactions and the Potential for Novel Preventative Strategies

Chronic hepatitis C virus (HCV) infections continue to be a major contributor to liver disease worldwide. HCV treatment has become highly effective, yet there are still no vaccines or prophylactic strategies available to prevent infection and allow effective management of the global HCV burden. Glycan-dependent interactions are crucial to many aspects of the highly complex HCV entry process, and also modulate immune evasion. This review provides an overview of the roles of viral and cellular glycans in HCV infection and highlights glycan-focused advances in the development of entry inhibitors and vaccines to effectively prevent HCV infection.

From Structural Studies to HCV Vaccine Design

Hepatitis C virus (HCV) is a serious and growing public health problem despite recent developments of antiviral therapeutics. To achieve global elimination of HCV, an effective cross-genotype vaccine is needed. The failure of previous vaccination trials to elicit an effective cross-reactive immune response demands better vaccine antigens to induce a potent cross-neutralizing response to improve vaccine efficacy. HCV E1 and E2 envelope (Env) glycoproteins are the main targets for neutralizing antibodies (nAbs), which aid in HCV clearance and protection. Therefore, a molecular-level understanding of the nAb responses against HCV is imperative for the rational design of cross-genotype vaccine antigens. Here we summarize the recent advances in structural studies of HCV Env and Env-nAb complexes and how they improve our understanding of immune recognition of HCV. We review the structural data defining HCV neutralization epitopes and conformational plasticity of the Env proteins, and the knowledge applicable to rational vaccine design.

EU FP7 research funding for an orphan drug (Orfadin®) and vaccine (Hep C) development: a success and a failure?

BACKGROUND

We considered the extent of the contribution of publicly funded research to the late-stage clinical development of pharmaceuticals and medicinal products, based on the European Commission (EC) FP7 research funding programme. Using two EC FP7-HEALTH case study examples-representing two types of outcomes-we then estimated wider public and charitable research funding contributions.

METHODS

Using the publicly available database of FP7-HEALTH funded projects, we identified awards relating to late-stage clinical development according to the systematic application of inclusion and exclusion criteria, classified them according to product type and clinical indication, and calculated total EC funding amounts. We then identified two case studies representing extreme outcomes: failure to proceed with the product (hepatitis C vaccine) and successful market authorisation (Orfadin® for alkaptonuria). Total public and philanthropic research funding contributions to these products were then estimated using publicly available information on funding.

RESULTS

12.3% (120/977) of all EC FP7-HEALTH awards related to the funding of late-stage clinical research, totalling € 686,871,399. Pharmaceutical products and vaccines together accounted for 84% of these late-stage clinical development research awards and 70% of its funding. The hepatitis C vaccine received total European Community (FP7 and its predecessor, EC Framework VI) funding of €13,183,813; total public and charitable research funding for this product development was estimated at € 77,060,102. The industry sponsor does not consider further development of this product viable; this now represents public risk investment. FP7 funding for the late-stage development of Orfadin® for alkaptonuria was so important that the trials it funded formed the basis for market authorisation, but it is not clear whether the price of the treatment (over €20,000 per patient per year) adequately reflects the substantial public funding contribution.

CONCLUSIONS

Public and charitable research funding plays an essential role, not just in early stage basic research, but also in the late-stage clinical development of products prior to market authorisation. In addition, it provides risk capital for failed products. Within this context, we consider further discussions about a public return on investment and its reflection in pricing policies and decisions justified.

T cell immunity to hepatitis C virus: Lessons for a prophylactic vaccine

There is consensus that HCV-specific T cells play a central role in the outcome (clearance vs. persistence) of acute infection and that they contribute to protection against the establishment of persistence after reinfection. However, these T cells often fail and the virus can persist, largely as a result of T cell exhaustion and the emergence of viral escape mutations. Importantly, HCV cure by direct-acting antivirals does not lead to a complete reversion of T cell exhaustion and thus HCV reinfections can occur. The current lack of detailed knowledge about the immunological determinants of viral clearance, persistence and protective immunity is a major roadblock to the development of a prophylactic T cell vaccine. This minireview highlights the basic concepts of successful T cell immunity, major mechanisms of T cell failure and how our understanding of these concepts can be translated into a prophylactic vaccine.

Polysaccharide-based chromatographic adsorbents for virus purification and viral clearance

Viruses still pose a significant threat to human and animal health worldwide. In the fight against viral infections, high-purity viral stocks are needed for manufacture of safer vaccines. It is also a priority to ensure the viral safety of biopharmaceuticals such as blood products. Chromatography techniques are widely implemented at both academic and industrial levels in the purification of viral particles, whole viruses and virus-like particles to remove viral contaminants from biopharmaceutical products. This paper focuses on polysaccharide adsorbents, particulate resins and membrane adsorbers, used in virus purification/removal chromatography processes. Different chromatographic modes are surveyed, with particular attention to ion exchange and affinity/pseudo-affinity adsorbents among which commercially available agarose-based resins (Sepharose®) and cellulose-based membrane adsorbers (Sartobind®) occupy a dominant position. Mainly built on the development of new ligands coupled to conventional agarose/cellulose matrices, the development perspectives of polysaccharide-based chromatography media in this antiviral area are stressed in the conclusive part.

Tumorigenesis, diagnosis, and therapeutic potential of exosomes in liver cancer

Hepatocellular carcinoma (HCC, also called primary liver cancer) is one of the most fatal cancers in the world. Due to the insidiousness of the onset of HCC and the lack of effective treatment methods, the prognosis of HCC is extremely poor, and the 5-year average survival rate is less than 10%. Exosomes are nano-sized microvesicle and contain various components such as nucleic acids, proteins, and lipids. Exosomes are important carriers for signal transmission or transportation of material from cell to cell or between cells and tissues. In recent years, exosomes have been considered as potential therapeutic targets of HCC. A large number of reports indicate that exosomes play a key role in the establishment of an HCC microenvironment, as well as the development, progression, invasion, metastasis, and even the diagnosis, treatment, and prognosis of HCC. However, the exact molecular mechanisms and roles of exosomes in these processes remain unclear. We believe that elucidation of the regulatory mechanism of HCC-related exosomes and its signaling pathway and analysis of its clinical applications in the diagnosis and treatment of HCC can provide useful clues for future treatment regimens for HCC. This article discusses and summarizes the research progress of HCC-related exosomes and their potential clinical applications.

Tumorigenesis, diagnosis, and therapeutic potential of exosomes in liver cancer

Hepatocellular carcinoma (HCC, also called primary liver cancer) is one of the most fatal cancers in the world. Due to the insidiousness of the onset of HCC and the lack of effective treatment methods, the prognosis of HCC is extremely poor, and the 5-year average survival rate is less than 10%. Exosomes are nano-sized microvesicle and contain various components such as nucleic acids, proteins, and lipids. Exosomes are important carriers for signal transmission or transportation of material from cell to cell or between cells and tissues. In recent years, exosomes have been considered as potential therapeutic targets of HCC. A large number of reports indicate that exosomes play a key role in the establishment of an HCC microenvironment, as well as the development, progression, invasion, metastasis, and even the diagnosis, treatment, and prognosis of HCC. However, the exact molecular mechanisms and roles of exosomes in these processes remain unclear. We believe that elucidation of the regulatory mechanism of HCC-related exosomes and its signaling pathway and analysis of its clinical applications in the diagnosis and treatment of HCC can provide useful clues for future treatment regimens for HCC. This article discusses and summarizes the research progress of HCC-related exosomes and their potential clinical applications.

Interferon-Induced Transmembrane Proteins Mediate Viral Evasion in Acute and Chronic Hepatitis C Virus Infection

Although adaptive immune responses against hepatitis C virus (HCV) infection have been studied in great detail, the role of innate immunity in protection against HCV infection and immune evasion is only partially understood. Interferon-induced transmembrane proteins (IFITMs) are innate effector proteins restricting host cell entry of many enveloped viruses, including HCV. However, the clinical impact of IFITMs on HCV immune escape remains to be determined. Here, we show that IFITMs promote viral escape from the neutralizing antibody (nAb) response in clinical cohorts of HCV-infected patients. Using pseudoparticles bearing HCV envelope proteins from acutely infected patients, we show that HCV variants isolated preseroconversion are more sensitive to the antiviral activity of IFITMs than variants from patients isolated during chronic infection postseroconversion. Furthermore, HCV variants escaping nAb responses during liver transplantation exhibited a significantly higher resistance to IFITMs than variants that were eliminated posttransplantation. Gain-of-function and mechanistic studies revealed that IFITMs markedly enhance the antiviral activity of nAbs and suggest a cooperative effect of human monoclonal antibodies and IFITMs for antibody-mediated neutralization driving the selection pressure in viral evasion. Perturbation studies with the IFITM antagonist amphotericin B revealed that modulation of membrane properties by IFITM proteins is responsible for the IFITM-mediated blockade of viral entry and enhancement of antibody-mediated neutralization. Conclusion: Our results indicate IFITM proteins as drivers of viral immune escape and antibody-mediated HCV neutralization in acute and chronic HCV infection. These findings are of clinical relevance for the design of urgently needed HCV B-cell vaccines and might help to increase the efficacy of future vaccine candidates.

Single-Dose Vaccination with a Hepatotropic Adeno-associated Virus Efficiently Localizes T Cell Immunity in the Liver with the Potential To Confer Rapid Protection against Hepatitis C Virus

Hepatitis C virus (HCV) is a significant contributor to the global disease burden, and development of an effective vaccine is required to eliminate HCV infections worldwide. CD4+ and CD8+ T cell immunity correlates with viral clearance in primary HCV infection, and intrahepatic CD8+ tissue-resident memory T (TRM) cells provide lifelong and rapid protection against hepatotropic pathogens. Consequently, we aimed to develop a vaccine to elicit HCV-specific CD4+ and CD8+ T cells, including CD8+ TRM cells, in the liver, given that HCV primarily infects hepatocytes. To achieve this, we vaccinated wild-type BALB/c mice with a highly immunogenic cytolytic DNA vaccine encoding a model HCV (genotype 3a) nonstructural protein (NS5B) and a mutant perforin (pVAX-NS5B-PRF), as well as a recombinant adeno-associated virus (AAV) encoding NS5B (rAAV-NS5B). A novel fluorescent target array (FTA) was used to map immunodominant CD4+ T helper (TH) cell and cytotoxic CD8+ T cell epitopes of NS5B in vivo, which were subsequently used to design a KdNS5B451-459 tetramer and analyze NS5B-specific T cell responses in vaccinated mice in vivo The data showed that intradermal prime/boost vaccination with pVAX-NS5B-PRF was effective in eliciting TH and cytotoxic CD8+ T cell responses and intrahepatic CD8+ TRM cells, but a single intravenous dose of hepatotropic rAAV-NS5B was significantly more effective. As a T-cell-based vaccine against HCV should ideally result in localized T cell responses in the liver, this study describes primary observations in the context of HCV vaccination that can be used to achieve this goal.IMPORTANCE There are currently at least 71 million individuals with chronic HCV worldwide and almost two million new infections annually. Although the advent of direct-acting antivirals (DAAs) offers highly effective therapy, considerable remaining challenges argue against reliance on DAAs for HCV elimination, including high drug cost, poorly developed health infrastructure, low screening rates, and significant reinfection rates. Accordingly, development of an effective vaccine is crucial to HCV elimination. An HCV vaccine that elicits T cell immunity in the liver will be highly protective for the following reasons: (i) T cell responses against nonstructural proteins of the virus are associated with clearance of primary infection, and (ii) long-lived liver-resident T cells alone can protect against malaria infection of hepatocytes. Thus, in this study we exploit promising vaccination platforms to highlight strategies that can be used to evoke highly functional and long-lived T cell responses in the liver for protection against HCV.

Enhancing Hepatitis C virus pseudoparticles infectivity through p7NS2 cellular expression

Hepatitis C pseudoparticles (HCVpp) are used to evaluate HCV cell entry while screening for neutralizing antibodies induced upon vaccination or while screening for new antiviral drugs. In this work we explore the stable production of HCVpp aiming to reduce the variability associated with transient productions. The performance of stably produced HCVpp was assessed by evaluating the influence of Human Serum and the impact of CD81 cellular expression on the infectivity of HCVpp. After evaluating the performance of stably produced HCVpp we studied the effect of co-expressing p7NS2 openreading frame (ORF) on HCVpp infectivity. Our data clearly shows an enhanced infectivity of HCVpp_p7NS2. Even though the exact mechanism was not completely elucidated, the enhanced infectivity of HCVpp_p7NS2 is neither a result of an increase production of virus particles nor a result from increased envelope density. The inhibitory effect of p7 inhibitory molecules such as rimantadine suggests a direct contribution of p7 ion channel for the enhanced infectivity of HCVpp_p7NS2 which is coherent with a pH-dependent cell entry mechanism. In conclusion, we report the establishment of a stable production system of HCVpp with enhanced infectivity through the overexpression of p7NS2 ORF contributing to improve HCV entry assessment assays widely used in antiviral drug discovery and vaccine development.

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.

Toward DNA-Based T-Cell Mediated Vaccines to Target HIV-1 and Hepatitis C Virus: Approaches to Elicit Localized Immunity for Protection

Human immunodeficiency virus (HIV)-1 and hepatitis C virus (HCV) are major contributors to the global disease burden with many experts recognizing the requirement of an effective vaccine to bring a durable end to these viral epidemics. The most promising vaccine candidates that have advanced into pre-clinical models and the clinic to eliminate or provide protection against these chronic viruses are viral vectors [e.g., recombinant cytomegalovirus, Adenovirus, and modified vaccinia Ankara (MVA)]. This raises the question, is there a need to develop DNA vaccines against HIV-1 and HCV? Since the initial study from Wolff and colleagues which showed that DNA represents a vector that can be used to express transgenes durably in vivo, DNA has been regularly evaluated as a vaccine vector albeit with limited success in large animal models and humans. However, several recent studies in Phase I-IIb trials showed that vaccination of patients with recombinant DNA represents a feasible therapeutic intervention to even cure cervical cancer, highlighting the potential of using DNA for human vaccinations. In this review, we will discuss the limitations and the strategies of using DNA as a vector to develop prophylactic T cell-mediated vaccines against HIV-1 and HCV. In particular, we focus on potential strategies exploiting DNA vectors to elicit protective localized CD8⁺ T cell immunity in the liver for HCV and in the cervicovaginal mucosa for HIV-1 as localized immunity will be an important, if not critical component, of an efficacious vaccine against these viral infections.

Hepatic IFN-Induced Protein with Tetratricopeptide Repeats Regulation of HCV Infection

Interferons (IFNs) suppress viral infection through the induction of >400 interferon-stimulated genes (ISGs). Among ISGs, IFN-induced protein with tetratricopeptide repeats (IFITs) is one of the most potent and well-characterized ISGs. IFIT family consists of 4 cluster genes. It has been suggested that the antiviral action of each IFIT employs distinct mechanisms. In addition, it has been shown that each IFIT exhibits its antiviral properties partially in a pathogen-specific manner. To date, the expression profile of IFITs in the liver, as well as the antiviral potency of the individual IFITs in the regulation of hepatitis C virus (HCV) infection, is not yet fully defined. Our previous study found that the expression of hepatic IFITs is well correlated with the outcome of IFN-based antiviral therapy. This study explored the significance of each IFIT in the suppression of HCV. Our in vitro and in vivo studies with humanized liver chimeric mouse system revealed that IFIT1, 2, and 3/4 play an important role in the suppression of HCV. In addition, our in vitro experiment found that all IFITs possess a comparable anti-HCV potency. Follow-up studies collectively indicated that IFITs suppress HCV likely through 2 distinct mechanisms: (1) inhibition of internal ribosome entry site-dependent viral protein translation initiation complex according to experiments with bicistronic reporter assay as well as confocal microscopic analyses and (2) sequestration of viral genome based on an experiment using replication defective viral genome. In conclusion, our study defined the importance of IFITs in the regulation of HCV and also suggested the multifaceted antiviral actions.

Hepatitis C virus infection could affect the pathogenesis of ischemic heart diseases in northern Japan

AIMS

Previously, our group reported that lymphotropic hepatitis C virus (HCV) could induce various kinds of immune dysfunctions. The immune dysfunctions could cause vascular disease by inducing cryoglobulinemia. It has been reported that ischemic heart diseases might be caused by HCV. However, the infectious rate of HCV in patients with ischemic heart disease has not been clarified in northern Japan. Therefore, we tried to determine the rate of HCV infectivity in patients with ischemic heart disease.

METHODS

The target patients of this study were automatically selected using an electronic medical record system to exclude selection bias. The system identified 16 484 patients with ischemic heart disease who were included in this study. In addition, 12 902 subjects who had received medical checkups were included as the control group.

RESULTS

The positive rate of HCV antibody among the patients with ischemic disease in our hospital was 2.58%, which was significantly higher (P < 0.01) than in the medical checkup patients (0.84%). The positive rate of HCV antibody in the patients with ischemic heart disease in each age group was significantly higher than in the corresponding age groups of the medical checkup patients. The rate of chronic kidney disease in HCV antibody-positive patients treated by percutaneous coronary intervention (PCI) was significantly higher than in HCV antibody-negative patients treated by PCI (P = 0.02).

CONCLUSIONS

Hepatitis C virus infection might be associated with the pathogenesis of ischemic heart disease and HCV antibody positivity might be a risk factor for ischemic heart disease in northern Japan.

Hepatitis C: Is eradication possible?

Hepatitis C has a relevant global impact in terms of morbidity, mortality and economic costs, with more than 70 million people infected worldwide. In the resolution, "Transforming our world: the 2030 Agenda for Sustainable Development" was included as a focus area in the health-related goal with world leaders pledging to "combat" it by 2030. In response, WHO drafted the Global Viral Hepatitis Strategy carrying the ambitious targets to reduce the number of deaths by two-thirds and to increase treatment rates up to 80%. Despite the availability of highly effective therapeutic regimens based on direct-acting antivirals many barriers to HCV eradication still remain. They are related to awareness of the infection, linkage to care, availability of the therapeutic drug regimens and reinfection. Overall, if an effective prophylactic vaccine will not be available, HCV eradication appears difficult to achieve in the future.

Pseudotyping retrovirus like particles vaccine candidates with Hepatitis C virus envelope protein E2 requires the cellular expression of CD81

Hepatitis C virus (HCV) infects 3% of world population being responsible for nearly half a million deaths annually urging the need for a prophylactic vaccine. Retrovirus like particles are commonly used scaffolds for antigens presentation being the core of diverse vaccine candidates. The immunogenicity of host proteins naturally incorporated in retrovirus was hypothesized to impact the performance of retrovirus based vaccines. In this work, the capacity of engineered retrovirus like particles devoided of host protein CD81 to display HCV envelope antigens was compared to non-engineered particles. A persistent inability of CD81 negative VLPs to incorporate HCV E2 protein as a result from the inefficient transport of HCV E2 to the plasma membrane, was observed. This work enabled the identification of a CD81-mediated transport of HCV E2 while stressing the importance of host proteins for the development of recombinant vaccines.

Accelerating the elimination of viral hepatitis: a Lancet Gastroenterology & Hepatology Commission

Viral hepatitis is a major public health threat and a leading cause of death worldwide. Annual mortality from viral hepatitis is similar to that of other major infectious diseases such as HIV and tuberculosis. Highly effective prevention measures and treatments have made the global elimination of viral hepatitis a realistic goal, endorsed by all WHO member states. Ambitious targets call for a global reduction in hepatitis-related mortality of 65% and a 90% reduction in new infections by 2030. This Commission draws together a wide range of expertise to appraise the current global situation and to identify priorities globally, regionally, and nationally needed to accelerate progress. We identify 20 heavily burdened countries that account for over 75% of the global burden of viral hepatitis. Key recommendations include a greater focus on national progress towards elimination with support given, if necessary, through innovative financing measures to ensure elimination programmes are fully funded by 2020. In addition to further measures to improve access to vaccination and treatment, greater attention needs to be paid to access to affordable, high-quality diagnostics if testing is to reach the levels needed to achieve elimination goals. Simplified, decentralised models of care removing requirements for specialised prescribing will be required to reach those in need, together with sustained efforts to tackle stigma and discrimination. We identify key examples of the progress that has already been made in many countries throughout the world, demonstrating that sustained and coordinated efforts can be successful in achieving the WHO elimination goals.

High density Huh7.5 cell hollow fiber bioreactor culture for high-yield production of hepatitis C virus and studies of antivirals

Chronic hepatitis C virus (HCV) infection poses a serious global public health burden. Despite the recent development of effective treatments there is a large unmet need for a prophylactic vaccine. Further, antiviral resistance might compromise treatment efficiency in the future. HCV cell culture systems are typically based on Huh7 and derived hepatoma cell lines cultured in monolayers. However, efficient high cell density culture systems for high-yield HCV production and studies of antivirals are lacking. We established a system based on Huh7.5 cells cultured in a hollow fiber bioreactor in the presence or absence of bovine serum. Using an adapted chimeric genotype 5a virus, we achieved peak HCV infectivity and RNA titers of 7.6 log₁₀ FFU/mL and 10.4 log₁₀ IU/mL, respectively. Bioreactor derived HCV showed high genetic stability, as well as buoyant density, sensitivity to neutralizing antibodies AR3A and AR4A, and dependency on HCV co-receptors CD81 and SR-BI comparable to that of HCV produced in monolayer cell cultures. Using the bioreactor platform, treatment with the NS5A inhibitor daclatasvir resulted in HCV escape mediated by the NS5A resistance substitution Y93H. In conclusion, we established an efficient high cell density HCV culture system with implications for studies of antivirals and vaccine development.

Computational design of hepatitis C virus immunogens from host-pathogen dynamics over empirical viral fitness landscapes

Hepatitis C virus (HCV) afflicts 170 million people and kills 700 000 annually. Vaccination offers the most realistic and cost effective hope of controlling this epidemic, but despite 25 years of research, no vaccine is available. A major obstacle is HCV's extreme genetic variability and rapid mutational escape from immune pressure. Coupling maximum entropy inference with population dynamics simulations, we have employed a computational approach to translate HCV sequence databases into empirical landscapes of viral fitness and simulate the intrahost evolution of the viral quasispecies over these landscapes. We explicitly model the coupled host-pathogen dynamics by combining agent-based models of viral mutation with stochastically-integrated coupled ordinary differential equations for the host immune response. We validate our model in predicting the mutational evolution of the HCV RNA-dependent RNA polymerase (protein NS5B) within seven individuals for whom longitudinal sequencing data is available. We then use our approach to perform exhaustive in silico evaluation of putative immunogen candidates to rationally design tailored vaccines to simultaneously cripple viral fitness and block mutational escape within two selected individuals. By systematically identifying a small number of promising vaccine candidates, our empirical fitness landscapes and host-pathogen dynamics simulator can guide and accelerate experimental vaccine design efforts.

Exploring NS3/4A, NS5A and NS5B proteins to design conserved subunit multi-epitope vaccine against HCV utilizing immunoinformatics approaches

Hepatitis C virus (HCV) vaccines, designed to augment specific T-cell responses, have been designated as an important aspect of effective antiviral treatment. However, despite the current satisfactory progress of these vaccines, extensive past efforts largely remained unsuccessful in mediating clinically relevant anti-HCV activity in humans. In this study, we used a series of immunoinformatics approaches to propose a multiepitope vaccine against HCV by prioritizing 16 conserved epitopes from three viral proteins (i.e., NS34A, NS5A, and NS5B). The prioritised epitopes were tested for their possible antigenic combinations with each other along with linker AAY using structural modelling and epitope-epitope interactions analysis. An adjuvant (β-defensin) at the N-terminal of the construct was added to enhance the immunogenicity of the vaccine construct. Molecular dynamics (MD) simulation revealed the most stable structure of the proposed vaccine. The designed vaccine is potentially antigenic in nature and can form stable and significant interactions with Toll-like receptor 3 and Toll-like receptor 8. The proposed vaccine was also subjected to an in silico cloning approach, which confirmed its expression efficiency. These analyses suggest that the proposed vaccine can elicit specific immune responses against HCV; however, experimental validation is required to confirm the safety and immunogenicity profile of the proposed vaccine construct.

Analysis of Transmission Routes of Hepatitis C Virus Based on Virus Genotyping in 341 Cases with Different Suspected Initial Infection Time Points in Hunan Province, China

Background

Few investigations have been reported on the changing trends in transmission routes of hepatitis C virus (HCV) and the corresponding HCV genotype (GT) distribution in Hunan province, China.

Material/Methods

HCV GTs, suspected viral transmission routes, and time of initial infections were investigated in 341 HCV-infected patients in 2016.

Results

Genotype 1 (GT1) (72.1%) was the most prevalent HCV GT, followed by GT6 (17.6%), GT3 (7.6%), and GT2 (2.6%). GT4 and GT5 were not found. The predominant HCV transmission routes were blood-related routes (57.5%) and intravenous drug use (IDU) (15.0%); 52.2% of the patients got HCV infection before 1994, 25.6% from 1994 to 1998, and 22.2% after 1998; 93.5% of the infections via blood-related transmission routes were with HCV GT1, 61.5% via IDU or feculent sexual contact were with HCV GT6, and 50.0% via non-healthcare invasive procedures were with HCV GT6. HCV infections via IDU or feculent sexual behavior were more prevalent in young males, while infections via invasive cosmetic procedures occurred more in young females, and both had a shorter time interval from suspected infection to confirmed clinical diagnosis. Multinomial logistic regression confirmed the time points of the initial HCV infections and suspected viral transmission routes were correlated with HCV GT distribution.

Conclusions

HCV GT1 infections via blood-related transmission routes in Hunan province have continually decreased since 1994. However, younger patients infected with HCV, especially with HCV GT6 via IDU, feculent sexual behavior, and non-healthcare invasive procedures, have significantly increased.

Differential virus-specific CD8+ T-cell epitope repertoire in hepatitis C virus genotype 1 versus 4

Virus-specific CD8⁺ T-cell responses play an important role in the outcome of hepatitis C virus (HCV) infection. To date, most HCV-specific CD8⁺ T-cell epitopes have been defined in HCV genotype 1 infection. In contrast, the HCV genotype 4-specific CD8⁺ T-cell response is poorly defined. Here, we analysed whether known HCV-specific CD8⁺ T-cell epitopes are also recognized in HCV genotype 4-infected patients and set out to identify the first HCV genotype 4-specific CD8⁺ T-cell epitopes. We studied patients chronically infected with HCV genotype 1 (n = 20) or 4 (n = 21) using 91 well-described HCV-specific epitope peptides. In addition, we analysed 24 genotype 4-infected patients using 40 epitope candidates predicted using an in silico approach. HCV-specific CD8⁺ T-cell responses targeting previously described epitopes were detectable in the majority of genotype 1-infected patients (11 of 20). In contrast, patients infected with HCV genotype 4 rarely targeted these epitopes (4 of 21; P = .0247). Importantly, we were able to identify eight novel HCV genotype 4-specific CD8⁺ T-cell epitopes. Only one of these epitopes was shared between genotype 1 and genotype 4. These results indicate that there is little overlap between CD8⁺ T-cell repertoires targeting HCV genotype 1 and 4. Prophylactic vaccination studies based on HCV genotype 1 are currently underway. However, in countries with the highest prevalence of HCV infection, such as Egypt, most patients are infected with HCV genotype 4. Thus, prophylactic vaccination strategies need to be adapted to HCV genotype 4 before their application to regions where HCV genotype 4 is endemic.

Reversing immune dysfunction and liver damage after direct-acting antiviral treatment for hepatitis C

The introduction of small molecules targeting viral functions has caused a paradigm shift in hepatitis C virus (HCV) treatment. Administration of these direct-acting antivirals (DAAs) achieves a complete cure in almost all treated patients with short-duration therapy and minimal side effects. Although this is a major improvement over the previous pegylated interferon plus ribavirin (PEG-IFNα/RBV) standard-of-care treatment for HCV, remaining questions address several aspects of the long-term benefits of DAA therapy. Interferon (IFN)-based treatment with successful outcome was associated with substantial reduction in liver disease–related mortality. However, emerging data suggest a complex picture and several confounding factors that influence the effect of both IFN-based and DAA therapies on immune restoration and limiting liver disease progression. We review current knowledge of restoration of innate and HCV-specific immune responses in DAA-mediated viral elimination in chronic HCV infection, and we identify future research directions to achieve long-term benefits in all cured patients and reduce HCV-related liver disease morbidity and mortality.

2017 European guideline for the screening, prevention and initial management of hepatitis B and C infections in sexual health settings

This guideline updates the 2010 European guideline for the management of hepatitis B and C virus infections. It is primarily intended to provide advice on testing, prevention and initial management of viral hepatitis B and C for clinicians working in sexual health clinical settings in European countries. The guideline is in a new question and answer format based on clinical situations, from which population/intervention/comparison/outcome questions were formulated. Updates cover areas such as epidemiology, point-of-care tests for hepatitis B, hepatitis C risk and 'chemsex', and HIV pre-exposure prophylaxis and hepatitis B. We have also included a short paragraph on hepatitis E noting there is no evidence for sexual transmission. The guideline has been prepared in accordance with the Europe protocol for production available at http://www.iusti.org/regions/europe/pdf/2017/ProtocolForProduction2017.pdf.

Innate and Adaptive Immune Responses in Chronic HCV Infection

Hepatitis C virus (HCV) remains a public health problem of global importance, even in the era of potent directly-acting antiviral drugs. In this chapter, I discuss immune responses to acute and chronic HCV infection. The outcome of HCV infection is influenced by viral strategies that limit or delay the initiation of innate antiviral responses. This delay may enable HCV to establish widespread infection long before the host mounts effective T and B cell responses. HCV's genetic agility, resulting from its high rate of replication and its error prone replication mechanism, enables it to evade immune recognition. Adaptive immune responses fail to keep up with changing viral epitopes. Neutralizing antibody epitopes may be hidden by decoy structures, glycans, and lipoproteins. T cell responses fail due to changing epitope sequences and due to exhaustion, a phenomenon that may have evolved to limit immune-mediated pathology. Despite these difficulties, innate and adaptive immune mechanisms do impact HCV replication. Immune-mediated clearance of infection is possible, occurring in 20-50% of people who contract the disease. New developments raise hopes for effective immunological interventions to prevent or treat HCV infection.

Glycan Shielding and Modulation of Hepatitis C Virus Neutralizing Antibodies

Hepatitis C virus (HCV) envelope glycoprotein heterodimer, E1E2, plays an essential role in virus entry and assembly. Furthermore, due to their exposure at the surface of the virion, these proteins are the major targets of anti-HCV neutralizing antibodies. Their ectodomain are heavily glycosylated with up to 5 sites on E1 and up to 11 sites on E2 modified by N-linked glycans. Thus, one-third of the molecular mass of E1E2 heterodimer corresponds to glycans. Despite the high sequence variability of E1 and E2, N-glycosylation sites of these proteins are generally conserved among the seven major HCV genotypes. N-glycans have been shown to be involved in E1E2 folding and modulate different functions of the envelope glycoproteins. Indeed, site-directed mutagenesis studies have shown that specific glycans are needed for virion assembly and infectivity. They can notably affect envelope protein entry functions by modulating their affinity for HCV receptors and their fusion activity. Importantly, glycans have also been shown to play a key role in immune evasion by masking antigenic sites targeted by neutralizing antibodies. It is well known that the high mutational rate of HCV polymerase facilitates the appearance of neutralization resistant mutants, and occurrence of mutations leading to glycan shifting is one of the mechanisms used by this virus to escape host humoral immune response. As a consequence of the importance of the glycan shield for HCV immune evasion, the deletion of N-glycans also leads to an increase in E1E2 immunogenicity and can induce a more potent antibody response against HCV.

Recombinant Flag-tagged E1E2 glycoproteins from three hepatitis C virus genotypes are biologically functional and elicit cross-reactive neutralizing antibodies in mice

Hepatitis C virus (HCV) is a globally disseminated human pathogen for which no vaccine is currently available. HCV is highly diverse genetically and can be classified into 7 genotypes and multiple sub-types. Due to this antigenic variation, the induction of cross-reactive and at the same time neutralizing antibodies is a challenge in vaccine production. Here we report the analysis of immunogenicity of recombinant HCV envelope glycoproteins from genotypes 1a, 1b and 2a, with a Flag tag inserted in the hypervariable region 1 of E2. This modification did not affect protein expression or conformation or its capacity to bind the crucial virus entry factor, CD81. Importantly, in immunogenicity studies on mice, the purified E2-Flag mutants elicited high-titer, cross-reactive antibodies that were able to neutralize HCV infectious particles from two genotypes tested (1a and 2a). These findings indicate that E1E2-Flag envelope glycoproteins could be important immunogen candidates for vaccine aiming to induce broad HCV-neutralizing responses.

Induction of Genotype Cross-Reactive, Hepatitis C Virus-Specific, Cell-Mediated Immunity in DNA-Vaccinated Mice

A universal hepatitis C virus (HCV) vaccine should elicit multiantigenic, multigenotypic responses, which are more likely to protect against challenge with the range of genotypes and subtypes circulating in the community. A vaccine cocktail and vaccines encoding consensus HCV sequences are attractive approaches to achieve this goal. Consequently, in a series of mouse vaccination studies, we compared the immunogenicity of a DNA vaccine encoding a consensus HCV nonstructural 5B (NS5B) protein to that of a cocktail of DNA plasmids encoding the genotype 1b (Gt1b) and Gt3a NS5B proteins. To complement this study, we assessed responses to a multiantigenic cocktail regimen by comparing a DNA vaccine cocktail encoding Gt1b and Gt3a NS3, NS4, and NS5B proteins to a single-genotype NS3/4/5B DNA vaccine. To thoroughly evaluate in vivo cytotoxic T lymphocyte (CTL) and T helper (Th) cell responses against Gt1b and Gt3a HCV peptide-pulsed target cells, we exploited a novel fluorescent-target array (FTA). FTA and enzyme-linked immunosorbent spot (ELISpot) analyses collectively indicated that the cocktail regimens elicited higher responses to Gt1b and Gt3a NS5B proteins than those with the consensus vaccine, while the multiantigenic DNA cocktail significantly increased the responses to NS3 and NS5B compared to those elicited by the single-genotype vaccines. Thus, a DNA cocktail vaccination regimen is more effective than a consensus vaccine or a monovalent vaccine at increasing the breadth of multigenotypic T cell responses, which has implications for the development of vaccines for communities where multiple HCV genotypes circulate.IMPORTANCE Despite the development of highly effective direct-acting antivirals (DAA), infections with hepatitis C virus (HCV) continue, particularly in countries where the supply of DAA is limited. Furthermore, patients who eliminate the virus as a result of DAA therapy can still be reinfected. Thus, a vaccine for HCV is urgently required, but the heterogeneity of HCV strains makes the development of a universal vaccine difficult. To address this, we developed a novel cytolytic DNA vaccine which elicits robust cell-mediated immunity (CMI) to the nonstructural (NS) proteins in vaccinated animals. We compared the immune responses against genotypes 1 and 3 that were elicited by a consensus DNA vaccine or a DNA vaccine cocktail and showed that the cocktail induced higher levels of CMI to the NS proteins of both genotypes. This study suggests that a universal HCV vaccine can most readily be achieved by use of a DNA vaccine cocktail.

Identification of T cell and B cell epitopes against Indian HCV-genotype-3a for vaccine development- An in silico analysis

Hepatitis C virus (HCV) infects almost 150 million people and is a leading cause of liver disease worldwide. It has been classified into seven genotypes; the most common genotype affecting Indian population is genotype 3 (60-70%). Currently there is no vaccine for any genotype of HCV. In order to develop peptide based vaccine against HCV, it is important to identify the conservancy in the circulating genotypes, along with the Human Leucocyte Antigen (HLA) alleles in the target population. The present study aims to identify conserved CD4 and CD8 T cells and B cell epitopes against Indian HCV-genotype-3a using an in silico analysis. In the present study, 28 promiscuous CD4 T cell epitopes and some CD8 epitopes were identified. The NS4 region was predicted to be the most antigenic with maximum number of conserved and promiscuous CD4 T cell epitopes and CD8 T cell epitopes having strong and intermediate affinity towards a number of HLA alleles prevalent in Indian population. Additionally, some linear B cell epitopes were also identified, which could generate neutralizing antibodies. In order to ascertain the binding pattern of the identified epitopes with HLA alleles, molecular docking analysis was carried out. The authors suggest further experimental validation to investigate the immunogenicity of the identified epitopes.

A protein coevolution method uncovers critical features of the Hepatitis C Virus fusion mechanism

Amino-acid coevolution can be referred to mutational compensatory patterns preserving the function of a protein. Viral envelope glycoproteins, which mediate entry of enveloped viruses into their host cells, are shaped by coevolution signals that confer to viruses the plasticity to evade neutralizing antibodies without altering viral entry mechanisms. The functions and structures of the two envelope glycoproteins of the Hepatitis C Virus (HCV), E1 and E2, are poorly described. Especially, how these two proteins mediate the HCV fusion process between the viral and the cell membrane remains elusive. Here, as a proof of concept, we aimed to take advantage of an original coevolution method recently developed to shed light on the HCV fusion mechanism. When first applied to the well-characterized Dengue Virus (DENV) envelope glycoproteins, coevolution analysis was able to predict important structural features and rearrangements of these viral protein complexes. When applied to HCV E1E2, computational coevolution analysis predicted that E1 and E2 refold interdependently during fusion through rearrangements of the E2 Back Layer (BL). Consistently, a soluble BL-derived polypeptide inhibited HCV infection of hepatoma cell lines, primary human hepatocytes and humanized liver mice. We showed that this polypeptide specifically inhibited HCV fusogenic rearrangements, hence supporting the critical role of this domain during HCV fusion. By combining coevolution analysis and in vitro assays, we also uncovered functionally-significant coevolving signals between E1 and E2 BL/Stem regions that govern HCV fusion, demonstrating the accuracy of our coevolution predictions. Altogether, our work shed light on important structural features of the HCV fusion mechanism and contributes to advance our functional understanding of this process. This study also provides an important proof of concept that coevolution can be employed to explore viral protein mediated-processes, and can guide the development of innovative translational strategies against challenging human-tropic viruses.

Several virus-mediated molecular processes remain poorly described, which dampen the development of potent anti-viral therapies. Hence, new experimental strategies need to be undertaken to improve and accelerate our understanding of these processes. Here, as a proof of concept, we employ amino-acid coevolution as a tool to gain insights into the structural rearrangements of Hepatitis C Virus (HCV) envelope glycoproteins E1 and E2 during virus fusion with the cell membrane, and provide a basis for the inhibition of this process. Our coevolution analysis predicted that a specific domain of E2, the Back Layer (BL) is involved into significant conformational changes with E1 during the fusion of the HCV membrane with the cellular membrane. Consistently, a recombinant, soluble form of the BL was able to inhibit E1E2 fusogenic rearrangements and HCV infection. Moreover, predicted coevolution networks involving E1 and BL residues, as well as E1 and BL-adjacent residues, were found to modulate virus fusion. Our data shows that coevolution analysis is a powerful and underused approach that can provide significant insights into the functions and structural rearrangements of viral proteins. Importantly, this approach can also provide structural and molecular basis for the design of effective anti-viral drugs, and opens new perspectives to rapidly identify effective antiviral strategies against emerging and re-emerging viral pathogens.

Induction of humoural and cellular immunity by immunisation with HCV particle vaccine in a non-human primate model

OBJECTIVE

Although HCV is a major cause of chronic liver disease worldwide, there is currently no prophylactic vaccine for this virus. Thus, the development of an HCV vaccine that can induce both humoural and cellular immunity is urgently needed. To create an effective HCV vaccine, we evaluated neutralising antibody induction and cellular immune responses following the immunisation of a non-human primate model with cell culture-generated HCV (HCVcc).

DESIGN

To accomplish this, 10 common marmosets were immunised with purified, inactivated HCVcc in combination with two different adjuvants: the classically used aluminum hydroxide (Alum) and the recently established adjuvant: CpG oligodeoxynucleotide (ODN) wrapped by schizophyllan (K3-SPG).

RESULTS

The coadministration of HCVcc with K3-SPG efficiently induced immune responses against HCV, as demonstrated by the production of antibodies with specific neutralising activity against chimaeric HCVcc with structural proteins from multiple HCV genotypes (1a, 1b, 2a and 3a). The induction of cellular immunity was also demonstrated by the production of interferon-γ mRNA in spleen cells following stimulation with the HCV core protein. These changes were not observed following immunisation with HCVcc/Alum preparation. No vaccination-related abnormalities were detected in any of the immunised animals.

CONCLUSIONS

The current preclinical study demonstrated that a vaccine included both HCVcc and K3-SPG induced humoural and cellular immunity in marmosets. Vaccination with this combination resulted in the production of antibodies exhibiting cross-neutralising activity against multiple HCV genotypes. Based on these findings, the vaccine created in this study represents a promising, potent and safe prophylactic option against HCV.

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.

Knowledge, attitude and behaviour regarding hepatitis C virus infection amongst Brazilian dental students

AIM

Dental health professionals, including dental students, are at high risk of exposure to infection with the hepatitis C virus (HCV) through occupational percutaneous injuries and eye exposure. Further, fear of HCV infection is associated with discriminatory attitudes. The current study aimed to evaluate the knowledge about HCV infection amongst dental students and their attitudes towards patients infected with HCV.

METHODS

A cross-sectional survey was conducted amongst 340 Brazilian dental students from two public universities using an instrument containing information regarding demographic characteristics, knowledge of HCV and attitudes towards patients with HCV infection. Descriptive statistics, Fisher's exact test, Student's t-tests, Mann-Whitney U-test and multiple logistic regression (MLR) were carried out (P < 0.05 was considered significant).

RESULTS

Response rate was 90% (n = 306), and more than half (54%, n = 165) of participants had high knowledge level (above the mean); 97.7% (n = 299) demonstrated positive attitudes. MLR showed that high knowledge of dental students regarding HCV was substantially influenced by advancement in year of study (last year; P < 0.001) and type of university (federal; P = 0.049). Positive attitude towards HCV-infected patients was mainly influenced by age (P = 0.004) and male gender (P = 0.022).

CONCLUSIONS

These results demonstrated a satisfactory knowledge about HCV infection amongst dental students, but some gaps were observed, suggesting the importance of continuous education about HCV in this population to prevent HCV infection as well as discrimination and prejudice towards patients with hepatitis C.

Immunogenicity of an influenza virus-vectored vaccine carrying the hepatitis C virus protein epitopes in mice

Hepatitis C virus (HCV) has a devastating impact on human health, and infections can progress into liver fibrosis, cirrhosis, and hepatocellular carcinoma. There is no effective HCV vaccine. In this study, we rescued a recombinant PR8 influenza viral vector, called rgFLU-HCV_CE1E2, carrying the core and envelope glycoprotein (C/E1/E2) epitopes of HCV inserted into the influenza nonstructural protein 1 gene. The morphological characteristics of rgFLU-HCV_CE1E2 and the expression of the C/E1/E2 epitopes of HCV were examined. rgFLU-HCV_CE1E2 replicated in various cell lines, including MDCK, A549, and Huh7.5 cells. More importantly, in BALB/c mice immunized intranasally twice at a 21-day interval with 10⁴, 10⁵, or 10⁶ TCID₅₀ rgFLU-HCV_CE1E2, the viral vector induced a robust antibody response to influenza and HCV and potent IFN-γ and IL-4 secretion in response to HCV antigens in a dose-dependent manner. The rgFLU-HCV_CE1E2 virus also stimulated IFN-γ production by virus-specific peripheral blood mononuclear cells in patients with chronic HCV infection. The study demonstrated that rgFLU-HCV_CE1E2 carrying HCV antigens is immunogenic in vivo and has potential for the development of a HCV vaccine.

Extracellular Interactions between Hepatitis C Virus and Secreted Apolipoprotein E

Interactions between hepatitis C virus (HCV) and lipoproteins in humans play an important role in the efficient establishment of chronic infection. Apolipoprotein E (ApoE) on the HCV envelope mediates virus attachment to host cells as well as immune evasion. This interaction is thought to occur in hepatocytes, as ApoE plays dual functions in HCV assembly and maturation as well as cell attachment. In the present study, we found that secreted ApoE (sApoE) can also bind to viral particles via its C-terminal domain after HCV is released from the cell. Furthermore, the binding affinity of interactions between the sApoE N terminus and cell surface receptors affected HCV infectivity in a dose-dependent manner. The extracellular binding of sApoE to HCV is dependent on HCV envelope proteins, and recombinant HCV envelope proteins are also able to bind to sApoE. These results suggest that extracellular interactions between HCV and sApoE may potentially complicate vaccine development and studies of viral pathogenesis.IMPORTANCE End-stage liver disease caused by chronic HCV infection remains a clinical challenge, and there is an urgent need for a prophylactic method of controlling HCV infection. Because host immunity against HCV is poorly understood, additional investigations of host-virus interactions in the context of HCV are important. HCV is primarily transmitted through blood, which is rich in lipoproteins. Therefore, it is of interest to further determine how HCV interacts with lipoproteins in human blood. In this study, we found that secreted ApoE (sApoE), an exchangeable component found in lipoproteins, participates in extracellular interactions with HCV virions. More significantly, different variants of sApoE differentially affect HCV infection efficiency in a dose-dependent manner. These findings provide greater insight into HCV infection and host immunity and could help propel the development of new strategies for preventing HCV infection.

Extracellular lipid-free apolipoprotein E inhibits HCV replication and induces ABCG1-dependent cholesterol efflux

OBJECTIVE

The HCV life cycle and the lipid metabolism are inextricably intertwined. In the blood, HCV virions are associated with lipoproteins, forming lipoviroparticles (LVPs), which are the most infectious form of the virus. Apolipoprotein E (apoE), a key LVP component, plays an essential role in HCV entry, assembly and egress. ApoE is also a cell host factor involved in lipoprotein homeostasis. Although the majority of apoE is associated with lipoproteins, a lipid-free (LF) form exists in blood. However, the role of LF-apoE in both lipid metabolism and HCV life cycle is poorly understood.

DESIGN

In this study, using the cell culture-derived HCV model system in human hepatoma Huh7.5.1 cells and primary human hepatocytes (PHH), we investigated the effect of LF-apoE on the early steps of HCV life cycle and on the lipid metabolism of hepatic cells.

RESULTS

A dose-dependent decrease in HCV replication was observed when Huh7.5.1 cells and PHH were treated with increasing amounts of LF-apoE. We showed that LF-apoE acts on HCV replication independently of previously described apoE receptors. We observed that LF-apoE induced a marked hepatic cholesterol efflux via the ATP-binding cassette subfamily G member 1 (ABCG1) protein that in turn inhibits HCV replication. LF-apoE also increases both apolipoprotein AI and high-density lipoprotein production.

CONCLUSIONS

Our findings highlight a new mechanism in lipid metabolism regulation and interaction of the lipid metabolism with the HCV life cycle, which may be important for viral pathogenesis and might also be explored for antiviral therapy.

Immune protection against reinfection with nonprimate hepacivirus

Hepatitis C virus (HCV) displays a restricted host species tropism and only humans and chimpanzees are susceptible to infection. A robust immunocompetent animal model is still lacking, hampering mechanistic analysis of virus pathogenesis, immune control, and prophylactic vaccine development. The closest homolog of HCV is the equine nonprimate hepacivirus (NPHV), which shares similar features with HCV and thus represents an animal model to study hepacivirus infections in their natural hosts. We aimed to dissect equine immune responses after experimental NPHV infection and conducted challenge experiments to investigate immune protection against secondary NPHV infections. Horses were i.v. injected with NPHV containing plasma. Flow cytometric analysis was used to monitor immune cell frequencies and activation status. All infected horses became viremic after 1 or 2 wk and viremia could be detected in two horses for several weeks followed by a delayed seroconversion and viral clearance. Histopathological examinations of liver biopsies revealed mild, periportally accentuated infiltrations of lymphocytes, macrophages, and plasma cells with some horses displaying subclinical signs of hepatitis. Following viral challenge, an activation of equine immune responses was observed. Importantly, after a primary NPHV infection, horses were protected against rechallenge with the homologous as well as a distinct isolate with only minute amounts of circulating virus being detectable.

Hepatitis C virus infection

Hepatitis C virus (HCV) is a hepatotropic RNA virus that causes progressive liver damage, which might result in liver cirrhosis and hepatocellular carcinoma. Globally, between 64 and 103 million people are chronically infected. Major risk factors for this blood-borne virus infection are unsafe injection drug use and unsterile medical procedures (iatrogenic infections) in countries with high HCV prevalence. Diagnostic procedures include serum HCV antibody testing, HCV RNA measurement, viral genotype and subtype determination and, lately, assessment of resistance-associated substitutions. Various direct-acting antiviral agents (DAAs) have become available, which target three proteins involved in crucial steps of the HCV life cycle: the NS3/4A protease, the NS5A protein and the RNA-dependent RNA polymerase NS5B protein. Combination of two or three of these DAAs can cure (defined as a sustained virological response 12 weeks after treatment) HCV infection in >90% of patients, including populations that have been difficult to treat in the past. As long as a prophylactic vaccine is not available, the HCV pandemic has to be controlled by treatment-as-prevention strategies, effective screening programmes and global access to treatment.

Visualizing the Essential Role of Complete Virion Assembly Machinery in Efficient Hepatitis C Virus Cell-to-Cell Transmission by a Viral Infection-Activated Split-Intein-Mediated Reporter System

Hepatitis C virus (HCV) infects 2 to 3% of the world population and is a leading cause of liver diseases such as fibrosis, cirrhosis, and hepatocellular carcinoma. Many aspects of HCV study, ranging from molecular virology and antiviral drug development to drug resistance profiling, were supported by straightforward assays of HCV replication and infection. Among these assays, the HCV-dependent fluorescence relocalization (HDFR) system allowed live-cell visualization of infection without modifying the viral genome, but this strategy required careful recognition of the fluorescence relocalization pattern for its high fluorescence background in the cytoplasm. In this study, to achieve background-free visualization of HCV infection, a viral infection-activated split-intein-mediated reporter system (VISI) was devised. Uninfected Huh7.5.1-VISI cells show no background signal, while HCV infection specifically illuminates the nuclei of infected Huh7.5.1-VISI cells with either green fluorescent protein (GFP) or mCherry. Combining VISI-GFP and VISI-mCherry systems, we revisited HCV cell-to-cell transmission with clear-cut distinction of donor and recipient cells in a live-cell manner. Independently of virion assembly, exosomes have been reported to transfer HCV subgenomic RNA to initiate replication in uninfected cells, which suggested an assembly-free pathway. However, our data demonstrated that HCV structural genes and the p7 gene were essential for not only cell-free infectivity but also cell-to-cell transmission. Additionally, depletion of apolipoprotein E (ApoE) from donor cells but not from recipient cells significantly reduced HCV cell-to-cell transmission efficiency. In summary, we developed a background-free cell-based reporter system for convenient live-cell visualization of HCV infection, and our data indicate that complete HCV virion assembly machinery is essential for both cell-free and cell-to-cell transmission.

IMPORTANCE

Hepatitis C virus (HCV) infects hepatocytes via two pathways: cell-free infection and cell-to-cell transmission. Structural modules of the HCV genome are required for production of infectious cell-free virions; however, the role of specific genes within the structural module in cell-to-cell transmission is not clearly defined. Our data demonstrate that deletion of core, E1E2, and p7 genes individually results in no HCV cell-to-cell transmission and that ApoE knockdown from donor cells causes less-efficient cell-to-cell transmission. Thus, this work indicates that the complete HCV assembly machinery is required for HCV cell-to-cell transmission. At last, this work presents an optimized viral infection-activated split-intein-mediated reporter system for easy live-cell monitoring of HCV infection.

Inactivation of HCV and HIV by microwave: a novel approach for prevention of virus transmission among people who inject drugs

Hepatitis C virus (HCV) and human immunodeficiency virus (HIV-1) transmissions among people who inject drugs (PWID) continue to pose a challenging global health problem. Here, we aimed to analyse a universally applicable inactivation procedure, namely microwave irradiation, as a safe and effective method to reduce the risk of viral transmission. The exposure of HCV from different genotypes to microwave irradiation resulted in a significant reduction of viral infectivity. Furthermore, microwave irradiation reduced viral infectivity of HIV-1 and of HCV/HIV-1 suspensions indicating that this inactivation may be effective at preventing co-infections. To translate microwave irradiation as prevention method to used drug preparation equipment, we could further show that HCV as well as HIV-1 infectivity could be abrogated in syringes and filters. This study demonstrates the power of microwave irradiation for the reduction of viral transmission and establishment of this safety strategy could help reduce the transmission of blood-borne viruses.

Reinventing HCV Treatment: Past and Future Perspectives

This review paper summarizes the epidemiology of hepatitis C virus (HCV) and chronic HCV infection, including HCV virology and treatment regimens. Specifically, we focus on the evolution of past, current, and future HCV treatment options, the reasons for treatment failure, and the impact of resistance-associated variants on treatment success.

Hepatitis C genotype distribution in patient and blood donor samples in South Africa for the period 2008-2012

There are limited molecular epidemiological studies of hepatitis C at a national level in South Africa. The introduction of newer treatment modalities for hepatitis C requires knowledge of the genotypes as these may have different prognostic and therapeutic implications. This retrospective study describes genotype distributions of patients attending specialist clinics and a blood donor group studied during the period 2008-2012 in South Africa. Residual samples from diagnostic viral load testing from specialist clinics in South Africa (n=941) and from the South African National Blood Service (n=294) were analysed quantitatively by real-time PCR and genotyped using the Versant line probe assay or sequencing. Genotype 1 was predominant in blood donors (34%), whilst genotype 5a was prevalent in patients (36%). In the blood donor group, genotype 4 was detected for the first time. Genotype 2 was rare in the patient group and not detected in blood donors. Genotype 1 was the predominant genotype in the younger age groups (less than 30 years), whereas genotype 5a was found at higher proportions in the older age groups for both the patient and blood donor groups, comprising more than 60% of genotypes in those older than 50 years. Genotypes 1 and 5 were at highest proportions across all provinces compared to other genotypes. In blood donors, genotype 1 was predominant among Caucasians (43%) and genotype 5a among Blacks (54%). Such information is required for planning the impact on the health sector with regard to newly emerging therapies for hepatitis C and burden of disease.