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

Future Prospects, Approaches, and the Government's Role in the Development of a Hepatitis C Virus Vaccine

Developing a safe and effective vaccine against the hepatitis C virus (HCV) remains a top priority for global health. Despite recent advances in antiviral therapies, the high cost and limited accessibility of these treatments impede their widespread application, particularly in resource-limited settings. Therefore, the development of the HCV vaccine remains a necessity. This review article analyzes the current technologies, future prospects, strategies, HCV genomic targets, and the governmental role in HCV vaccine development. We discuss the current epidemiological landscape of HCV infection and the potential of HCV structural and non-structural protein antigens as vaccine targets. In addition, the involvement of government agencies and policymakers in supporting and facilitating the development of HCV vaccines is emphasized. We explore how vaccine development regulatory channels and frameworks affect research goals, funding, and public health policy. The significance of international and public-private partnerships in accelerating the development of an HCV vaccine is examined. Finally, the future directions for developing an HCV vaccine are discussed. In conclusion, the review highlights the urgent need for a preventive vaccine to fight the global HCV disease and the significance of collaborative efforts between scientists, politicians, and public health organizations to reach this important public health goal.

Hepatitis C: Standard of Treatment and What to Do for Global Elimination

Hepatitis C virus infection has a substantial effect on morbidity and mortality worldwide because it is a cause of cirrhosis, hepatocellular carcinoma, liver transplantation, and liver-related death. Direct acting antiviral drugs available today have high efficacy and excellent safety and can be used in all patients with clinically evident chronic liver disease and in groups that demonstrate risk behaviors to reduce the spread of infection. The Global Health Strategy of WHO to eliminate hepatitis infection by 2030 assumes "a 90% reduction in new cases of chronic hepatitis C, a 65% reduction in hepatitis C deaths, and treatment of 80% of eligible people with HCV infections". In this review effective models and strategies for achieving the global elimination of HCV infection are analyzed. The screening strategies must be simple and equally effective in high-risk groups and in the general population; fast and effective models for appropriate diagnosis of liver disease are needed; strategies for direct acting antiviral drug selection must be cost-effective; linkage to care models in populations at risk and in marginalized social classes must be specifically designed and applied; strategies for obtaining an effective vaccine against HCV infection have yet to be developed.

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.

State of the art vaccination strategies as primary prevention to reduce incidence of gastrointestinal cancers

Immunizations have influenced the epidemiology of numerous gastrointestinal cancers. Human papillomavirus (HPV) is a common sexually transmitted infection (STI). Although most infections are transient and asymptomatic, persistent infections with oncogenic strains of HPV can progress to cervical, anal, penile, vaginal, vulvar, and oropharyngeal cancers. The introduction of HPV vaccinations has drastically reduced incidences of HPV-vaccine related infections and HPV related cervical cancers. The vaccine has proven to be safe and effective however, HPV vaccination rates have yet to reach target goals in the U.S. and many countries worldwide have not incorporated the vaccine into national immunization programs. The first successful nationwide vaccination program was employed against hepatitis B virus (HBV) in Taiwan in 1984 and demonstrated a statistically significant decrease in the incidence of hepatocellular carcinoma (HCC) in the 6 to 10 years after implementation of universal HBV vaccinations in infants. Twenty-year follow-up studies have continued to demonstrate statistically significant decreased rates of HBV related HCC among vaccinated populations. Despite the successful decrease in incidence of HBV-related HCC, efforts to create an effective prophylactic vaccination against hepatitis C virus (HCV) to prevent chronic HCV infection and its associated morbidity, including HCV-related HCC, have to date been unsuccessful.

Development of a structural epitope mimic: an idiotypic approach to HCV vaccine design

HCV vaccine development is stymied by the high genetic diversity of the virus and the variability of the envelope glycoproteins. One strategy to overcome this is to identify conserved, functionally important regions—such as the epitopes of broadly neutralizing antibodies (bNAbs)—and use these as a basis for structure-based vaccine design. Here, we report an anti-idiotype approach that has generated an antibody that mimics a highly conserved neutralizing epitope on HCV E2. Crucially, a mutagenesis screen was used to identify the antibody, designated B2.1 A, whose binding characteristics to the bNAb AP33 closely resemble those of the original antigen. Protein crystallography confirmed that B2.1 A is a structural mimic of the AP33 epitope. When used as an immunogen B2.1 A induced antibodies that recognized the same epitope and E2 residues as AP33 and most importantly protected against HCV challenge in a mouse model.

Full-length genome sequencing of RNA viruses-How the approach can enlighten us on hepatitis C and hepatitis E viruses

Among the five main viruses responsible for human hepatitis, hepatitis C virus (HCV) and hepatitis E virus (HEV) are different while sharing similarities. Both viruses can be transmitted by blood or derivatives whereas HEV can also follow environmental or zoonotic routes. These highly variable RNA viruses can cause chronic hepatitis potentially leading to hepatocarcinoma. HCV and HEV can develop new structures and functions under selective pressure to adapt to host immunity, human tissues, treatments or even various animal reservoirs. Elsewhere, with directly acting antiviral treatments, HCV can be eradicated whereas HEV is an emerging pathogen against which specific treatments have to be improved. As a unique molecular tool able to explore viral genomic plasticity, full-length genome (FLG) sequencing has become easier, faster and cheaper. The present review will show how FLG sequencing can explore these RNA viruses with the aim to investigate key genomics data to improve basic knowledge, patients' healthcare and preventive tools.

Analysis of drug-resistance-associated mutations and genetic barriers in hepatitis C virus NS5B sequences in China

The hepatitis C virus (HCV) NS5B protein is an RNA-dependent RNA polymerase that is required for viral genome replication and constitutes the most important target region for drugs being developed as direct-acting antivirals (DAAs) against HCV genotype 1. However, the extreme genetic variability leading to drug resistance mutations and genetic barriers has dramatically compromised the effectiveness of DAA therapy. The purpose of this study was to analyze the genetic variability of NS5B polymerase in HCV patients from different provinces of China to identify the impact of these resistance sites on genetic barriers. We analyzed 3489 NS5B sequences of HCV strains circulating in different regions of China, obtained from the GenBank database, 153 of which were from three cities in Sichuan Province (Yibin, Zigong and Zhangzhou). Sequence alignment was conducted using MEGA 6.0, the genetic information was translated into amino acids, and the percentage of polymorphic amino acid sites was calculated. The Vijver method was used to evaluate the occurrence of genetic barriers in HCV NS5B sequences. Blood samples were collected from 153 HCV patients from Sichuan for NS5B sequence analysis using real-time PCR and the Sanger method. Of the 17 antiviral drug resistance sites summarized from the published literature, nine were found in Chinese NS5B sequences, and C316Y was identified as the dominant mutation. Analysis of genetic barriers revealed that the probability of mutation to a drug-resistance-associated amino acid, in response to selective pressure from antiviral drugs was 100% at site 96 and 99.7% at site 282. Our study is the first to analyze the drug resistance sites and to evaluate genetic barriers in NS5B sequences that could affect the responsiveness of Chinese HCV patients to DAA therapy. The results provide a valuable basis for drug development and introduction of foreign-origin antiviral drugs in China that targeting the HCV NS5B region.

Safety Profile of a Multi-Antigenic DNA Vaccine Against Hepatitis C Virus

Despite direct acting antivirals (DAAs) curing >95% of individuals infected with hepatitis C (HCV), in order to achieve the World Health Organization HCV Global Elimination Goals by 2030 there are still major challenges that need to be overcome. DAAs alone are unlikely to eliminate HCV in the absence of a vaccine that can limit viral transmission. Consequently, a prophylactic HCV vaccine is necessary to relieve the worldwide burden of HCV disease. DNA vaccines are a promising vaccine platform due to their commercial viability and ability to elicit robust T-cell-mediated immunity (CMI). We have developed a novel cytolytic DNA vaccine that encodes non-structural HCV proteins and a truncated mouse perforin (PRF), which is more immunogenic than the respective canonical DNA vaccine lacking PRF. Initially we assessed the ability of the HCV pNS3-PRF and pNS4/5-PRF DNA vaccines to elicit robust long-term CMI without any adverse side-effects in mice. Interferon-γ (IFN-γ) enzyme-linked immunosorbent spot (ELISpot) assay was used to evaluate CMI against NS3, NS4 and NS5B in a dose-dependent manner. This analysis showed a dose-dependent bell-curve of HCV-specific responses in vaccinated animals. We then thoroughly examined the effects associated with reactogenicity of cytolytic DNA vaccination with the multi-antigenic HCV DNA vaccine (pNS3/4/5B). Hematological, biochemical and histological studies were performed in male Sprague Dawley rats with a relative vaccine dose 10–20-fold higher than the proposed dose in Phase I clinical studies. The vaccine was well tolerated, and no toxicity was observed. Thus, the cytolytic multi-antigenic DNA vaccine is safe and elicits broad memory CMI.

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.

Mononuclear phagocyte system in hepatitis C virus infection

The mononuclear phagocyte system (MPS), which consists of monocytes, dendritic cells (DCs), and macrophages, plays a vital role in the innate immune defense against pathogens. Hepatitis C virus (HCV) is efficient in evading the host immunity, thereby facilitating its development into chronic infection. Chronic HCV infection is the leading cause of end-stage liver diseases, liver cirrhosis, and hepatocellular carcinoma. Acquired immune response was regarded as the key factor to eradicate HCV. However, innate immunity can regulate the acquired immune response. Innate immunity-derived cytokines shape the adaptive immunity by regulating T-cell differentiation, which determines the outcome of acute HCV infection. Inhibition of HCV-specific T-cell responses is one of the most important strategies for immune system evasion. It is meaningful to illustrate the role of innate immune response in HCV infection. With the MPS being the important factor in innate immunity, therefore, understanding the role of the MPS in HCV infection will shed light on the pathophysiology of chronic HCV infection. In this review, we outline the impact of HCV infection on the MPS and cytokine production. We discuss how HCV is detected by the MPS and describe the function and impairment of MPS components in HCV infection.

Defining the interval for monitoring potential adverse events following immunization (AEFIs) after receipt of live viral vectored vaccines

Live viral vectors that express heterologous antigens of the target pathogen are being investigated in the development of novel vaccines against serious infectious agents like HIV and Ebola. As some live recombinant vectored vaccines may be replication-competent, a key challenge is defining the length of time for monitoring potential adverse events following immunization (AEFI) in clinical trials and epidemiologic studies. This time period must be chosen with care and based on considerations of pre-clinical and clinical trials data, biological plausibility and practical feasibility. The available options include: (1) adapting from the current relevant regulatory guidelines; (2) convening a panel of experts to review the evidence from a systematic literature search to narrow down a list of likely potential or known AEFI and establish the optimal risk window(s); and (3) conducting "near real-time" prospective monitoring for unknown clustering's of AEFI in validated large linked vaccine safety databases using Rapid Cycle Analysis for pre-specified adverse events of special interest (AESI) and Treescan to identify previously unsuspected outcomes. The risk window established by any of these options could be used along with (4) establishing a registry of clinically validated pre-specified AESI to include in case-control studies. Depending on the infrastructure, human resources and databases available in different countries, the appropriate option or combination of options can be determined by regulatory agencies and investigators.

Development of a recombinant murine tumour model using hepatoma cells expressing hepatitis C virus nonstructural antigens

Hepatitis C virus (HCV) chronically infects 2%-3% of the world's population, causing liver disease and cancer with prolonged infection. The narrow host range of the virus, being restricted largely to human hepatocytes, has made the development of relevant models to evaluate the efficacy of vaccines a challenge. We have developed a novel approach to accomplish this by generating a murine hepatoma cell line stably expressing nonstructural HCV antigens which can be used in vitro or in vivo to test HCV vaccine efficacies. These HCV-recombinant hepatoma cells formed large solid-mass tumours when implanted into syngeneic mice, allowing us to test candidate HCV vaccines to demonstrate the development of an HCV-specific immune response that limited tumour growth. Using this model, we tested the therapeutic potential of recombinant anti-HCV-specific vaccines based on two fundamentally different attenuated pathogen vaccine systems-attenuated Salmonella and recombinant adenoviral vector based vaccine. While attenuated Salmonella that secreted HCV antigens limited growth of the HCV-recombinant tumours when used in a therapeutic vaccination trial, replication-competent but noninfectious adenovirus expressing nonstructural HCV antigens showed overall greater survival and reduced weight loss compared to non-replicating nondisseminating adenovirus. Our results demonstrate a model with anti-tumour responses to HCV nonstructural (NS) protein antigens and suggest that recombinant vaccine vectors should be explored as a therapeutic strategy for controlling HCV and HCV-associated cancers.

Hepatitis C Virus Infection and Vaccine Development

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

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.

Probing the antigenicity of hepatitis C virus envelope glycoprotein complex by high-throughput mutagenesis

The hepatitis C virus (HCV) envelope glycoproteins E1 and E2 form a non-covalently linked heterodimer on the viral surface that mediates viral entry. E1, E2 and the heterodimer complex E1E2 are candidate vaccine antigens, but are technically challenging to study because of difficulties in producing natively folded proteins by standard protein expression and purification methods. To better comprehend the antigenicity of these proteins, a library of alanine scanning mutants comprising the entirety of E1E2 (555 residues) was created for evaluating the role of each residue in the glycoproteins. The mutant library was probed, by a high-throughput flow cytometry-based assay, for binding with the co-receptor CD81, and a panel of 13 human and mouse monoclonal antibodies (mAbs) that target continuous and discontinuous epitopes of E1, E2, and the E1E2 complex. Together with the recently determined crystal structure of E2 core domain (E2c), we found that several residues in the E2 back layer region indirectly impact binding of CD81 and mAbs that target the conserved neutralizing face of E2. These findings highlight an unexpected role for the E2 back layer in interacting with the E2 front layer for its biological function. We also identified regions of E1 and E2 that likely located at or near the interface of the E1E2 complex, and determined that the E2 back layer also plays an important role in E1E2 complex formation. The conformation-dependent reactivity of CD81 and the antibody panel to the E1E2 mutant library provides a global view of the influence of each amino acid (aa) on E1E2 expression and folding. This information is valuable for guiding protein engineering efforts to enhance the antigenic properties and stability of E1E2 for vaccine antigen development and structural studies.

Preclinical Development and Production of Virus-Like Particles As Vaccine Candidates for Hepatitis C

Hepatitis C Virus (HCV) infects 2% of the world’s population and is the leading cause of liver disease and liver transplantation. It poses a serious and growing worldwide public health problem that will only be partially addressed with the introduction of new antiviral therapies. However, these treatments will not prevent re-infection particularly in high risk populations. The introduction of a HCV vaccine has been predicted, using simulation models in a high risk population, to have a significant effect on reducing the incidence of HCV. A vaccine with 50 to 80% efficacy targeted to high-risk intravenous drug users could dramatically reduce HCV incidence in this population. Virus like particles (VLPs) are composed of viral structural proteins which self-assemble into non-infectious particles that lack genetic material and resemble native viruses. Thus, VLPs represent a safe and highly immunogenic vaccine delivery platform able to induce potent adaptive immune responses. Currently, many VLP-based vaccines have entered clinical trials, while licensed VLP vaccines for hepatitis B virus (HBV) and human papilloma virus (HPV) have been in use for many years. The HCV core, E1 and E2 proteins can self-assemble into immunogenic VLPs while inclusion of HCV antigens into heterogenous (chimeric) VLPs is also a promising approach. These VLPs are produced using different expression systems such as bacterial, yeast, mammalian, plant, or insect cells. Here, this paper will review HCV VLP-based vaccines and their immunogenicity in animal models as well as the different expression systems used in their production.

Epidemiology of viral hepatitis in the Republic of Congo: review

Objective

Considered an endemic zone, Republic of Congo has a high seroprevalence rate of hepatitis B and C virus. To know the extent of hepatitis infection as a public health problem, we reviewed published literature and other sources for reports of these viral infections in the country.

Results

High seroprevalence of HBV and HCV carriage in blood donors were observed in studies confirming Congo’s place in the hyperendemic area of HBV and HCV infection. These prevalence were compared by Chi square test. We compared the prevalence of three studies conducted in 1996, 2015 and 2016. The statistical results were very significant. HBV genotype E was most prevalent. Very few studies were done on pregnant women. Difficulties in the care and management of patients were also noted because of the high cost of often unavailable treatments. Difficulties arise, however, when an attempt was made to implement the National Hepatitis Control Program. Despite studies conducted on hepatitis prevalence, health interventions are still needed to care and manage these patients and the need to implement the national hepatitis control is more pressing in the Congo.

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.

Structure-Based Design of Hepatitis C Virus Vaccines That Elicit Neutralizing Antibody Responses to a Conserved Epitope

Despite recent advances in therapeutic options, hepatitis C virus (HCV) remains a severe global disease burden, and a vaccine can substantially reduce its incidence. Due to its extremely high sequence variability, HCV can readily escape the immune response; thus, an effective vaccine must target conserved, functionally important epitopes. Using the structure of a broadly neutralizing antibody in complex with a conserved linear epitope from the HCV E2 envelope glycoprotein (residues 412 to 423; epitope I), we performed structure-based design of immunogens to induce antibody responses to this epitope. This resulted in epitope-based immunogens based on a cyclic defensin protein, as well as a bivalent immunogen with two copies of the epitope on the E2 surface. We solved the X-ray structure of a cyclic immunogen in complex with the HCV1 antibody and confirmed preservation of the epitope conformation and the HCV1 interface. Mice vaccinated with our designed immunogens produced robust antibody responses to epitope I, and their serum could neutralize HCV. Notably, the cyclic designs induced greater epitope-specific responses and neutralization than the native peptide epitope. Beyond successfully designing several novel HCV immunogens, this study demonstrates the principle that neutralizing anti-HCV antibodies can be induced by epitope-based, engineered vaccines and provides the basis for further efforts in structure-based design of HCV vaccines.IMPORTANCE Hepatitis C virus is a leading cause of liver disease and liver cancer, with approximately 3% of the world's population infected. To combat this virus, an effective vaccine would have distinct advantages over current therapeutic options, yet experimental vaccines have not been successful to date, due in part to the virus's high sequence variability leading to immune escape. In this study, we rationally designed several vaccine immunogens based on the structure of a conserved epitope that is the target of broadly neutralizing antibodies. In vivo results in mice indicated that these antigens elicited epitope-specific neutralizing antibodies, with various degrees of potency and breadth. These promising results suggest that a rational design approach can be used to generate an effective vaccine for this virus.

Why highly effective drugs are not enough: the need for an affordable solution to eliminating HCV

INTRODUCTION

Because of the rapid pace of development of new direct-acting antiviral (DAA) drugs, chronic hepatitis C virus (HCV) infection is now increasingly considered curable. However, the emphasis on DAA therapies disregards key issues related to cost, availability, and antiviral resistance. Areas covered: This perspective provides an overview of current HCV therapies and the development of DAAs, followed by a discussion of the limitations of DAA therapy. A literature search was used to select relevant studies, and a web search for relevant news articles and press releases was conducted. Expert commentary: Despite cure rates exceeding 90%, now is not the time to declare victory against HCV but to reinforce recent progress by addressing the issues of cost and availability as well as by developing strategies to manage antiviral resistance. Future drug development efforts should place greater emphasis on targeting host factors required for HCV replication, for which the barrier to resistance is higher, and effort should continue to develop a vaccine against HCV. Finally, efforts should be made to facilitate large-scale screening in endemic areas to identify and treat patients as early as possible to reduce long-term risks of advanced liver disease and their attendant costs of management.

Prevalence of Hepatitis C virus Genotype 3a in patients with Hodgkin and Non-Hodgkin Lymphoma

BACKGROUND AND OBJECTIVES

Hepatitis C virus (HCV) is a major public health problem worldwide. Replication and persistence of HCV genome have been described in the liver tissue as well as B cells lymphocyte. Several investigations have reported that long-term persistence of HCV in B cells may result in Hodgkin and Non-Hodgkin lymphoma. This study was aimed to determine frequency of HCV RNA in histological tissues obtained from patients suffered from Hodgkin and Non-Hodgkin lymphoma.

MATERIALS AND METHODS

52 formalin-fixed paraffin-embedded tissue blocks including 23 (44.3%) Hodgkin and 29 (55.7%) Non-Hodgkin samples were collected and five micrometer sections were prepared. RNA was extracted and cDNA was synthesized. Two consecutive Nested RT-PCR assays were carried out for detection of HCV 5' UTR and core gene. RT-PCR products were sequenced and aligned to construct HCV phylogenic tree to evaluate the homology of sequences in comparison to the reference sequences retrieved from Genbank.

RESULTS

Overall, 6 Non-Hodgkin (20.6%) and 3 Hodgkin lymphoma (13.04%) samples showed positive PCR results for both 5' UTR and HCV core RNA via nested PCR (P<0.469). Sequencing results revealed that all detected HCV RNA samples belonged to the genotype 3a.

CONCLUSION

Despite low prevalence of HCV infection in Iran, high frequency of HCV RNA genotypes 3a (17.3%) has been found in patients with Hodgkin and Non-Hodgkin lymphoma. To improve treatment regimens, screening of HCV RNA in patients suffered from Hodgkin or Non-Hodgkin lymphoma is recommended which can be done through highly sensitive molecular means before and after immunosuppression status.

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.

HCV NS4B targets Scribble for proteasome-mediated degradation to facilitate cell transformation

Hepatitis C virus (HCV) nonstructural protein 4B (NS4B) is a multi-transmembrane protein, but little is known about how NS4B contributes to HCV replication and tumorigenesis. Its C-terminal domain (CTD) has been shown to associate with intracellular membrane, and we have previously shown that NS4B CTD contains a class I PDZ-binding motif (PBM). Here, we demonstrated that NS4B PBM interacts with the PDZ-containing tumor suppressor protein, Scribble, using immunofluorescence and co-immunoprecipitation assays, and this interaction requires at least three contiguous PDZ domains of Scribble. In addition, NS4B PBM specifically induced Scribble degradation by activating the proteasome-ubiquitin pathway. Similar Scribble degradation was also observed in HCV-infected cells, suggesting NS4B could work in the context of HCV. Finally, NS4B PBM mutants showed reduced colony formation capacity compared with its wild-type counterpart, indicating that NS4B PBM plays important roles in NS4B-mediated cell transformation. Altogether, we provide a mechanism by which NS4B induces cell transformation through its PBM, which specifically interacts with the PDZ domains of Scribble and targets Scribble for degradation.

Genetic Barrier to Direct Acting Antivirals in HCV Sequences Deposited in the European Databank

Background & Aims

Development of resistance results from mutations in the viral genome, and the presence of selective drug pressure leads to the emergence of a resistant virus population. The aim of this study was to analyze the impact of genetic variability on the genetic barrier to drug resistance to DAAs.

Methods

The genetic barrier was quantified based on the number and type of nucleotide mutations required to impart resistance, considering full-length HCV NS3, NS5A and NS5B regions segregated by genotype into subtypes 1a, 1b, 2a, 2b and 3a. This study analyzeds 789 NS3 sequences, 708 sequences and 536 NS5B sequences deposited in the European Hepatitis C Virus Database, in the following resistance-associated positions: NS3: F43/I/L/S/V, Q80K/R, R155K/G, A156G/S/T and D168A/C/E/G/H/N/T/V/Y; NS5A: L/M28A/T/V, Q30E/H/R, L31F/I/M/V, H58D or P58S and Y93C/F/H/N/S; NS5B: S282P/R/T, C316H/N/Y, S368T, Y448C/H, S556G/R, D559R.

Results

Variants that require only one transversion in NS3 were found in 4 positions and include F43S, R80K, R155K/G and A156T. The genetic barrier to resistance shows subtypic differences at position 155 of the NS3 gene where a single transition is necessary in subtype 1a. In the NS5A gene, 5 positions where only one nucleotide change can confer resistance were found, such as L31M which requires one transversion in all subtypes, except in 0.28% of 1b sequences; and R30H, generated by a single transition, which was found in 10.25% of the sequences of genotype 1b. Other subtypic differences were observed at position 58, where resistance is less likely in genotype 1a because a transversion is required to create the variant 58S. For the NS5B inhibitors, the genetic barrier at positions conferring resistance was nearly identical in subtypes 1a and 1b, and single transitions or transversions were necessary in 5 positions to generate a drug-resistant variant of HCV. The positions C316Y and S556D required only one transition in all genotypes, Y448H and S556 G/N/R positions required only one transition for up to 98.8% of the sequences analyzed. A single variant in position 448 in genotype 1a is less likely to become the resistance variant 448H because it requires two transversions. Also, in the position 559D a transversion and a transition were necessary to generate the resistance mutant D559H.

Conclusion

Results revealed that in 14 out of 16 positions, conversion to a drug-resistant variant of HCV required only one single nucleotide substitutions threatening direct acting antivirals from all three classes.

Highly-Immunogenic Virally-Vectored T-cell Vaccines Cannot Overcome Subversion of the T-cell Response by HCV during Chronic Infection

An effective therapeutic vaccine for the treatment of chronic hepatitis C virus (HCV) infection, as an adjunct to newly developed directly-acting antivirals (DAA), or for the prevention of reinfection, would significantly reduce the global burden of disease associated with chronic HCV infection. A recombinant chimpanzee adenoviral (ChAd3) vector and a modified vaccinia Ankara (MVA), encoding the non-structural proteins of HCV (NSmut), used in a heterologous prime/boost regimen induced multi-specific, high-magnitude, durable HCV-specific CD4+ and CD8+ T-cell responses in healthy volunteers, and was more immunogenic than a heterologous Ad regimen. We now assess the immunogenicity of this vaccine regimen in HCV infected patients (including patients with a low viral load suppressed with interferon/ribavirin therapy), determine T-cell cross-reactivity to endogenous virus, and compare immunogenicity with that observed previously in both healthy volunteers and in HCV infected patients vaccinated with the heterologous Ad regimen. Vaccination of HCV infected patients with ChAd3-NSmut/MVA-NSmut was well tolerated. Vaccine-induced HCV-specific T-cell responses were detected in 8/12 patients; however, CD4+ T-cell responses were rarely detected, and the overall magnitude of HCV-specific T-cell responses was markedly reduced when compared to vaccinated healthy volunteers. Furthermore, HCV-specific cells had a distinct partially-functional phenotype (lower expression of activation markers, granzyme B, and TNFα production, weaker in vitro proliferation, and higher Tim3 expression, with comparable Tbet and Eomes expression) compared to healthy volunteers. Robust anti-vector T-cells and antibodies were induced, showing that there is no global defect in immunity. The level of viremia at the time of vaccination did not correlate with the magnitude of the vaccine-induced T-cell response. Full-length, next-generation sequencing of the circulating virus demonstrated that T-cells were only induced by vaccination when there was a sequence mismatch between the autologous virus and the vaccine immunogen. However, these T-cells were not cross-reactive with the endogenous viral variant epitopes. Conversely, when there was complete homology between the immunogen and circulating virus at a given epitope T-cells were not induced. T-cell induction following vaccination had no significant impact on HCV viral load. In vitro T-cell culture experiments identified the presence of T-cells at baseline that could be expanded by vaccination; thus, HCV-specific T-cells may have been expanded from pre-existing low-level memory T-cell populations that had been exposed to HCV antigens during natural infection, explaining the partial T-cell dysfunction. In conclusion, vaccination with ChAd3-NSmut and MVA-NSmut prime/boost, a potent vaccine regimen previously optimized in healthy volunteers was unable to reconstitute HCV-specific T-cell immunity in HCV infected patients. This highlights the major challenge of overcoming T-cell exhaustion in the context of persistent antigen exposure.

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.

Hepatitis C-A clinical review

With an estimated prevalence of about 170 million people worldwide, chronic hepatitis C is an important cause of chronic liver disease associated with a substantial risk of cirrhosis and hepatocellular carcinoma. The recent past has borne witness to remarkable advancements in the treatment of chronic hepatitis C with the development of novel, effective, and well tolerated medications that have resulted in paradigm shifts in treatment approaches and may potentially affect the natural history of the disease. We provide a clinical review of current concepts and future developments in the management of chronic hepatitis C to aid in the understanding and individualization of chronic hepatitis C treatment. J. Med. Virol. 88:1844-1855, 2016. © 2016 Wiley Periodicals, Inc.

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.

Designing and Development of a DNA Vaccine Based On Structural Proteins of Hepatitis C Virus

BACKGROUND

Hepatitis C virus (HCV) infection is one of the most prevalent infectious diseases responsible for high morbidity and mortality worldwide. Therefore, designing new and effective therapeutics is of great importance. The aim of the current study was to construct a DNA vaccine containing structural proteins of HCV and evaluation of its expression in a eukaryotic system.

METHODS

Structural proteins of HCV (core, E1, and E2) were isolated and amplified from JFH strain of HCV genotype 2a using PCR method. The PCR product was cloned into pCDNA3.1 (+) vector and finally were confirmed by restriction enzyme analysis and sequencing methods. The eukaryotic expression of the vector was confirmed by RT-PCR.

RESULTS

A recombinant vector containing 2241bp fragment of HCV structural genes was constructed. The desired plasmid was sequenced and corresponded to 100% identity with the submitted sequences in GenBank. RT-PCR results indicated that the recombinant plasmid could be expressed efficiently in the eukaryotic expression system.

CONCLUSION

Successful cloning of structural viral genes in pCDNA3.1 (+) vector and their expression in the eukaryotic expression system facilitates the development of new DNA vaccines against HCV. A DNA vaccine encoding core-E1-E2 antigens was designed. The desired expression vector can be used for further attempts in the development of vaccines.

Cellular immune response to hepatitis-C-virus in subjects without viremia or seroconversion: is it important?

Hepatitis C Virus (HCV) causes chronic infection and represents a global health burden. To date, there is no licensed vaccine for HCV. The high viral replication rate and the existence of several HCV genotypes and quasispecies hamper the development of an effective universal vaccine. In this regard, the current HCV vaccine candidates show genotype-specific protection or narrow cross reactivity against other genotypes. Importantly, HCV spontaneous clearance occurs in 15-50 % of infected subjects, indicating that natural resistance to chronic infection exists. This phenomenon was demonstrated among humans and chimpanzees and continues to motivate researchers attempting to develop an effective HCV vaccine. However, what constitutes a protective immune response or correlate of protection against HCV infection is still vague. Additionally, the mechanisms behind successful HCV clearance suggest the coordination of several arms of the immune system, with cell-mediated immunity (CMI) playing a crucial role in this process. By contrast, although neutralizing antibodies have been identified, they are isolate-specific and poorly correlate with viral clearance. Antigen-specific CD4 T cells, instead, correlate with transient decline in HCV viremia and long-lasting control of the infection. Unfortunately, HCV has been very successful in evading host immune mechanisms, leading to complications such as liver fibrosis, cirrhosis and hepatocellular carcinoma. Interestingly, CMI to HCV antigens were shown among exposed individuals without viremia or seroconversion, suggesting the clearance of prior HCV infection(s). These individuals include family members living with HCV-infected subjects, healthcare workers, IV drug users, and sexual contacts. The correlates of protection could be closely monitored among these individuals. This review provides a summary of HCV-specific immune responses in general and of CMI in particular in these cohorts. The importance of these CMI responses are discussed.

Knowledge, risk perception, and behavioral intention about hepatitis C, among university students

INTRODUCTION

Hepatitis C virus (HCV) infection is a major complex public health problem. Different resources have proved that healthcare workers more than the general population are at a risk of infection. Therefore, medical field students, due to the future occupational hazards, are included in the risk group.

AIM

The purpose of the study was to evaluate the level of knowledge, public and individual risk perception, and behavioral intention about HCV, among medical sciences students of the Isfahan University of Medical Sciences.

SETTINGS AND DESIGN

This is a descriptive-analytical study that was conducted among 457 students of the Medical Sciences in the Isfahan University of Medical Sciences.

MATERIALS AND METHODS

The data was collected using a questionnaire. Sampling was done randomly.

STATISTICAL ANALYSIS USED

The data was analyzed using the SPSS18 software and statistical tests of Pearson, Spearman, T- test, and the analysis of variance (ANOVA); P < 0.05 was considered significant.

RESULTS

Four hundred and fifty-seven students (41.8% male and 58.2% female) in 29 fields of study (six categories) participated in this research. The mean age was 21.55 ± 2.6 years. The mean and standard deviations of the students' knowledge was 3.71 ± 2.9 (out of 8), and the behavioral intention to accruing information and performance of preventive actions related to HCV was 11.52 ± 3.16 (out of 20). Public risk perception was 20.1 ± 3.5 (out of 30); and personal risk perception was 6.96 ± 1.8 (out of 10). The ANOVA test showed that public perception of the risk among students of different academic fields was different (F = 1.52, P < 0.05).

CONCLUSIONS

According to the low knowledge of students of Medical Sciences in the Isfahan University of Medical Sciences about HCV, it was recommended that the University Policymakers design an educational intervention about it, in order to minimize the chances of being infected.

Update on hepatitis C: Direct-acting antivirals

Hepatitis C virus (HCV) was discovered 26 years ago. For decades, interferon-based therapy has been the mainstay of treatment for HCV. Recently, several direct-acting antivirals (DAAs) have been approved for treatment of HCV-infected patients and to help combat the virus. These drugs have revolutionized the management of HCV as all-oral regimens with favorable side effect profiles and superior rates of sustained virological response. Emerging real-world data are demonstrating results comparable to registration trials for DAA agents. Suddenly, the potential for eradicating HCV is on the horizon.

Empirical fitness models for hepatitis C virus immunogen design

Hepatitis C virus (HCV) afflicts 170 million people worldwide, 2%-3% of the global population, and kills 350 000 each year. Prophylactic vaccination offers the most realistic and cost effective hope of controlling this epidemic in the developing world where expensive drug therapies are not available. Despite 20 years of research, the high mutability of the virus and lack of knowledge of what constitutes effective immune responses have impeded development of an effective vaccine. Coupling data mining of sequence databases with spin glass models from statistical physics, we have developed a computational approach to translate clinical sequence databases into empirical fitness landscapes quantifying the replicative capacity of the virus as a function of its amino acid sequence. These landscapes explicitly connect viral genotype to phenotypic fitness, and reveal vulnerable immunological targets within the viral proteome that can be exploited to rationally design vaccine immunogens. We have recovered the empirical fitness landscape for the HCV RNA-dependent RNA polymerase (protein NS5B) responsible for viral genome replication, and validated the predictions of our model by demonstrating excellent accord with experimental measurements and clinical observations. We have used our landscapes to perform exhaustive in silico screening of 16.8 million T-cell immunogen candidates to identify 86 optimal formulations. By reducing the search space of immunogen candidates by over five orders of magnitude, our approach can offer valuable savings in time, expense, and labor for experimental vaccine development and accelerate the search for a HCV vaccine.

ABBREVIATIONS

HCV-hepatitis C virus, HLA-human leukocyte antigen, CTL-cytotoxic T lymphocyte, NS5B-nonstructural protein 5B, MSA-multiple sequence alignment, PEG-IFN-pegylated interferon.

The structural HCV genes delivered by MPG cell penetrating peptide are directed to enhance immune responses in mice model

One of the significant problems in vaccination projects is the lack of an effective vaccine against hepatitis C virus (HCV). The goal of the current study is to evaluate and compare two DNA constructs encoding HCV core and coreE1E2 genes alone or complexed with MPG peptide as a delivery system for stimulation of antibody responses and IFN-γ secretion in Balb/c mice model. Indeed, MPG cell penetrating peptide was used to improve DNA immunization in mice. Our results demonstrated that MPG forms stable non-covalent nanoparticles with pcDNA-core and pcDNA-coreE1E2 at an N/P ratio of 10:1. The in vitro transfection efficiency of core or coreE1E2 DNA using MPG and TurboFect delivery systems was confirmed by western blot analysis. The results indicated the expression of the full-length core (∼21 kDa), and coreE1E2 (∼83 kDa) proteins using an anti-His monoclonal antibody. In addition, the expression of HCV core and coreE1E2 proteins was performed in bacteria and the purified recombinant proteins were injected to mice with Montanide 720 adjuvant. Our data showed that the immunized mice with HCV core and coreE1E2 proteins generated the mixture of sera IgG1 and IgG2a isotypes considerably higher than other groups. Furthermore, DNA constructs encoding core and coreE1E2 complexed with MPG could significantly induce IFN-γ secretion in lower concentrations than the naked core and coreE1E2 DNAs. Taken together, the DNA formulations as well as protein regimens used in this study triggered high-level IFN-γ production in mice, an important feature for the development of Th1 immune responses.

Heterologous Expression of Hepatitis C Virus Core Protein in Oil Seeds of Brassica napus L

Background:

Hepatitis c virus (HCV), prevalent among 3% of the world population, is a major worldwide public health concern and an effective vaccination could help to overcome this problem. Plant seeds as low-cost vaccine expression platforms are highly desirable to produce antigens.

Objectives:

The present study was aimed at investigating the possible expression of recombinant HCV core protein, as a leading HCV vaccine candidate, in canola (Brassica napus) plant seeds in order to be used as an effective immunogen for vaccine researches.

Materials and Methods:

A codon-optimized gene harboring the Kozak sequence, 6 × His-tag, HCVcp (1 - 122 residues) and KDEL (Lys-Asp-Glu-Leu) peptide in tandem was designed and expressed under the control of the seed specific promoter, fatty acid elongase 1 (FAE1), to accumulate the recombinant protein in canola (B. napus L.) seeds. Transgenic lines were screened and the presence of the transgene was confirmed in the T0 plants by polymerase chain reaction (PCR). The quantity and quality of the HCV core protein (HCVcp) in transgenic seeds were evaluated by enzyme-linked immunosorbent assay (ELISA) and western blot, respectively.

Results:

Western blot analysis using anti-His antibody confirmed the presence of a 15 kDa protein in the seeds of T1 transgenic lines. The amount of antigenic protein accumulated in the seeds of these transgenic lines was up to 0.05% of the total soluble protein (TSP).

Conclusions:

The canola oilseeds could provide a useful expression system to produce HCV core protein as a vaccine candidate.

Design and expression of fusion protein consists of HBsAg and Polyepitope of HCV as an HCV potential vaccine

BACKGROUND

Hepatitis C virus (HCV) infection is a serious public health threat worldwide. Cellular immune responses, especially cytotoxic T-lymphocytes (CTLs), play a critical role in immune response toward the HCV clearance. Since polytope vaccines have the ability to stimulate the cellular immunity, a recombinant fusion protein was developed in this study.

MATERIALS AND METHODS

The designed fusion protein is composed of hepatitis B surface antigen (HBsAg), as an immunocarrier, fused to an HCV polytope sequence. The polytope containing five immunogenic epitopes of HCV was designed to induce specific CTL responses. The construct was cloned into the pET-28a, and its expression was investigated in BL21 (DE3), BL21 pLysS, BL21 pLysE, and BL21 AI Escherichia coli strains using 12% gel sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Finally, the identity of expressed fusion protein was confirmed by Western blotting using anti-His monoclonal antibody and affinity chromatography was applied to purify the expressed protein.

RESULTS

The accuracy of the construct was confirmed by restriction map analysis and sequencing. The transformation of the construct into the BL21 (DE3), pLysS, and pLysE E. coli strains did not lead to any expression. The fusion protein was found to be toxic for E. coli DE3. By applying two steps inhibition, the fusion protein was successfully expressed in BL21 (AI) E. coli strain.

CONCLUSION

The HBsAg-polytope fusion protein expressed in this study can be further evaluated for its immunogenicity in animal models.

Geographic distribution of HCV genotypes in Libya and analysis of risk factors involved in their transmission

Background

Hepatitis C virus (HCV) genotypes have been shown to be differently distributed between distinct geographical areas. Libya is a large country has the longest coast in the Mediterranean basin. Information regarding hepatitis C genotypes and subtypes circulating in Libya are not well known. The objectives of this study were to determine the frequency of various HCV genotypes cross Libya and the demographic and attributable risk factors associated with HCV transmission among Libyan population.

Methods

A cross-sectional study was carried out on patients with recently confirmed HCV infection. A total of 3,227 serum samples enrolled at 19 collection center cross Libya. 1,756 belonged to Tripoli region, 452 to West region 355 to North region, 181 South regions and 483 East region. The samples were tested by type specific genotyping assay and correlated with demographic and potential risk factors within the studied populations.

Results

A total of 20 discrete genotypes and subtypes were identified among the Libyan population ranging from 11.5 to 0.3 % cross the country. Genotype 1 was the most frequent among all regions (19.7–40.5 %), reaching the highest value in Tripoli region, followed by genotype 4 which was more prevalent in the South (49.3 %) and West (40.0 %) regions. Genotype 3, was higher in Tripoli (21.3 %) and East (15.9 %) regions while genotype 2, common in North (23.6 %) and South (22.5 %) regions. However, we found evidence that there is a changing relative prevalence of HCV genotypes in relation to age, gender and the mode of transmission which is reflected in the predominance of certain genotypes among Libyan population.

Conclusions

Different HCV genotypes were isolated form Libyan population including newly emerged ones. The prevalence of the genotypes varied by geographic region and influenced by demographic and risk factors. Knowing the frequency and distribution of the genotypes would provide key information on understanding the spread of HCV in Libya and this could be greatly reflected on national plans and future strategies for infection prevention.

Identification and retrospective validation of T-cell epitopes in the hepatitis C virus genotype 4 proteome: an accelerated approach toward epitope-driven vaccine development

With over 150 million people chronically infected worldwide and millions more infected annually, hepatitis C continues to pose a burden on the global healthcare system. The standard therapy of hepatitis C remains expensive, with severe associated side effects and inconsistent cure rates. Vaccine development against the hepatitis C virus has been hampered by practical and biological challenges posed by viral evasion mechanisms. Despite these challenges, HCV vaccine research has presented a number of candidate vaccines that progressed to phase II trials. However, those efforts focused mainly on HCV genotypes 1 and 2 as vaccine targets and barely enough attention was given to genotype 4, the variant most prevalent in the Middle East and central Africa. We describe herein the in silico identification of highly conserved and immunogenic T-cell epitopes from the HCV genotype 4 proteome, using the iVAX immunoinformatics toolkit, as targets for an epitope-driven vaccine. We also describe a fast and inexpensive approach for results validation using the empirical data on the Immune Epitope Database (IEDB) as a reference. Our analysis identified 90 HLA class I epitopes of which 20 were found to be novel and 19 more had their binding predictions retrospectively validated; empirical data for the remaining 51 epitopes was insufficient to validate their binding predictions. Our analysis also identified 14 HLA class II epitopes, of which 8 had most of their binding predictions validated. Further investigation is required regarding the efficacy of the identified epitopes as vaccine targets in populations where HCV genotype 4 is most prevalent.

Hepatitis C

Hepatitis C virus (HCV) infection is a major health problem worldwide. The effects of chronic infection include cirrhosis, end-stage liver disease, and hepatocellular carcinoma. As a result of shared routes of transmission, co-infection with HIV is a substantial problem, and individuals infected with both viruses have poorer outcomes than do peers infected with one virus. No effective vaccine exists, although persistent HCV infection is potentially curable. The standard of care has been subcutaneous interferon alfa and oral ribavirin for 24-72 weeks. This treatment results in a sustained virological response in around 50% of individuals, and is complicated by clinically significant adverse events. In the past 10 years, advances in HCV cell culture have enabled an improved understanding of HCV virology, which has led to development of many new direct-acting antiviral drugs that target key components of virus replication. These direct-acting drugs allow for simplified and shortened treatments for HCV that can be given as oral regimens with increased tolerability and efficacy than interferon and ribavirin. Remaining obstacles include access to appropriate care and treatment, and development of a vaccine.

Clinical testing of a dendritic cell targeted therapeutic vaccine in patients with chronic hepatitis C virus infection

The lack of antiviral cellular immune responses in patients with chronic hepatitis C virus (HCV) infection suggests that T-cell vaccines may provide therapeutic benefit. Due to the central role that dendritic cells (DC) play in the activation of T-cell responses, our aim was to carry out a therapeutic vaccination clinical trial in HCV patients using DC. Five patients with chronic HCV infection were vaccinated with three doses of 5 × 10⁶ or 10⁷ autologous DC transduced with a recombinant adenovirus encoding NS3 using the adapter protein CFh40L, which facilitates DC transduction and maturation. No significant adverse effects were recorded after vaccination. Treatment caused no changes in serum liver enzymes nor in viral load. Vaccination induced weak but consistent expansion of T-cell responses against NS3 and adenoviral antigens. Patients’ DC, as opposed to murine DC or DC from healthy subjects, secreted high IL-10 levels after transduction, inducing the activation of IL-10–producing T cells. IL-10 blockade during vaccine preparation restored its ability to stimulate anti-NS3 Th1 responses. Thus, vaccination with adenovirus-transduced DC is safe and induces weak antiviral immune responses. IL-10 associated with vaccine preparation may be partly responsible for these effects, suggesting that future vaccines should consider concomitant inhibition of this cytokine.

Co-expression analysis of differentially expressed genes in hepatitis C virus-induced hepatocellular carcinoma

The aim of the current study was to investigate the molecular mechanisms underlying hepatitis C virus (HCV)-induced hepatocellular carcinoma (HCC) using the expression profiles of HCV-infected Huh7 cells at different time points. The differentially expressed genes (DEGs) were identified with the Samr package in R software once the data were normalized. Functional and pathway enrichment analysis of the identified DEGs was also performed. Subsequently, MCODE in Cytoscape software was applied to conduct module analysis of the constructed co-expression networks. A total of 1,100 DEGs were identified between the HCV-infected and control samples at 12, 18, 24 and 48 h post-infection. DEGs at 24 and 48 h were involved in the same signaling pathways and biological processes, including sterol biosynthetic processes and tRNA amino-acylation. There were 22 time series genes which were clustered into 3 expression patterns, and the demarcation point of the 2 expression patterns that 401 overlapping DEGs at 24 and 48 h clustered into was 24 h post-infection. tRNA synthesis-related biological processes emerged at 24 and 48 h. Replication and assembly of HCV in HCV-infected Huh7 cells occurred mainly at 24 h post-infection. In view of this, the screened time series genes have the potential to become candidate target molecules for monitoring, diagnosing and treating HCV-induced HCC.

Targeting regulatory T cells to improve vaccine immunogenicity in early life

Human newborns and infants are bombarded with multiple pathogens on leaving the sterile intra-uterine environment, and yet have suboptimal innate immunity and limited immunological memory, thus leading to increased susceptibility to infections in early life. They are thus the target age group for a host of vaccines against common bacterial and viral pathogens. They are also the target group for many vaccines in development, including those against tuberculosis (TB), malaria, and HIV infection. However, neonatal and infant responses too many vaccines are suboptimal, and in the case of the polysaccharide vaccines, it has been necessary to develop the alternative conjugated formulations in order to induce immunity in early life. Immunoregulatory factors are an intrinsic component of natural immunity necessary to dampen or control immune responses, with the caveat that they may also decrease immunity to infections or lead to chronic infection. This review explores the key immunoregulatory factors at play in early life, with a particular emphasis on regulatory T cells (Tregs). It goes on to explore the role that Tregs play in limiting vaccine immunogenicity, and describes animal and human studies in which Tregs have been depleted in order to enhance vaccine responses. A deeper understanding of the role that Tregs play in limiting or controlling vaccine-induced immunity would provide strategies to improve vaccine immunogenicity in this critical age group. New adjuvants and drugs are being developed that can transiently suppress Treg function, and their use as part of human vaccination strategies against infections is becoming a real prospect for the future.

Assessing the feasibility of hepatitis C virus vaccine trials: results from the Hepatitis C Incidence and Transmission Study-community (HITS-c) vaccine preparedness study

Efficacy trials of preventive hepatitis C virus (HCV) vaccine candidates raise challenging scientific and ethical issues. Based on data from the first 3 years of a community-based prospective observational study - the Hepatitis C Incidence and Transmission Study-community (HITS-c) - this paper examines the feasibility of conducting trials of candidate HCV vaccines with people who inject drugs (PWID) in Sydney, Australia. Of the 166 PWID confirmed HCV antibody negative and eligible for enrolment, 156 (94%) completed baseline procedures. Retention was high, with 89% of participants retained at 48 weeks and 76% of participants completing at least 75% of study visits within 2 weeks of schedule. The rate of primary HCV infection was 7.9/100 py (95% CI 4.9, 12.7). Of the 17 incident cases, 16 completed at least one follow-up assessment and 12 (75%) had evidence of chronic viraemia with progression to chronic HCV infection estimated to be 6/100 py. Power calculations suggest a chronic HCV infection rate of at least 12/100 py (primary HCV infection rate 16/100 py) will be required for stand-alone trials of highly efficacious candidates designed to prevent chronic infection. However, elevated primary HCV infection was observed among participants not receiving opioid substitution therapy who reported heroin as the main drug injected (26.9/100 py, 95% CI 14.5, 50.0) and those who reported unstable housing (23.5/100 py, 95% CI 7.6, 72.8), daily or more frequent injecting (22.7/100 py, 95% CI 12.2, 42.2) and receptive syringe sharing (23.6/100 py, 95% CI 9.8, 56.7) in the 6 months prior to baseline. These data suggest that it is possible to recruit and retain at-risk PWID who adhere to study protocols and that modification of eligibility criteria may identify populations with sufficiently high HCV incidence. Results support the feasibility of large multi-centre HCV vaccine trials, including in the Australian setting.

Dendritic cell-mediated, DNA-based vaccination against hepatitis C induces the multi-epitope-specific response of humanized, HLA transgenic mice

Hepatitis C virus (HCV) is the etiologic agent of chronic liver disease, hepatitis C. Spontaneous resolution of viral infection is associated with vigorous HLA class I- and class II-restricted T cell responses to multiple viral epitopes. Unfortunately, only 20% of patients clear infection spontaneously, most develop chronic disease and require therapy. The response to chemotherapy varies, however; therapeutic vaccination offers an additional treatment strategy. To date, therapeutic vaccines have demonstrated only limited success. Vector-mediated vaccination with multi-epitope-expressing DNA constructs alone or in combination with chemotherapy offers an additional treatment approach. Gene sequences encoding validated HLA-A2- and HLA-DRB1-restricted epitopes were synthesized and cloned into an expression vector. Dendritic cells (DCs) derived from humanized, HLA-A2/DRB1 transgenic (donor) mice were transfected with these multi-epitope-expressing DNA constructs. Recipient HLA-A2/DRB1 mice were vaccinated s.c. with transfected DCs; control mice received non-transfected DCs. Peptide-specific IFN-γ production by splenic T cells obtained at 5 weeks post-immunization was quantified by ELISpot assay; additionally, the production of IL-4, IL-10 and TNF-α were quantified by cytokine bead array. Splenocytes derived from vaccinated HLA-A2/DRB1 transgenic mice exhibited peptide-specific cytokine production to the vast majority of the vaccine-encoded HLA class I- and class II-restricted T cell epitopes. A multi-epitope-based HCV vaccine that targets DCs offers an effective approach to inducing a broad immune response and viral clearance in chronic, HCV-infected patients.

Global fold and backbone dynamics of the hepatitis C virus E2 glycoprotein transmembrane domain determined by NMR

E1 and E2 are two hepatitis C viral envelope glycoproteins that assemble into a heterodimer that is essential for membrane fusion and penetration into the target cell. Both extracellular and transmembrane (TM) glycoprotein domains contribute to this interaction, but study of TM-TM interactions has been limited because synthesis and structural characterization of these highly hydrophobic segments present significant challenges. In this NMR study, by successful expression and purification of the E2 transmembrane domain as a fusion construct we have determined the global fold and characterized backbone motions for this peptide incorporated in phospholipid micelles. Backbone resonance frequencies, relaxation rates and solvent exposure measurements concur in showing this domain to adopt a helical conformation, with two helical segments spanning residues 717-726 and 732-746 connected by an unstructured linker containing the charged residues D728 and R730 involved in E1 binding. Although this linker exhibits increased local motions on the ps timescale, the dominating contribution to its relaxation is the global tumbling motion with an estimated correlation time of 12.3ns. The positioning of the helix-linker-helix architecture within the mixed micelle was established by paramagnetic NMR spectroscopy and phospholipid-peptide cross relaxation measurements. These indicate that while the helices traverse the hydrophobic interior of the micelle, the linker lies closer to the micelle perimeter to accommodate its charged residues. These results lay the groundwork for structure determination of the E1/E2 complex and a molecular understanding of glycoprotein heterodimerization.

Modulation of hepatitis C virus core DNA vaccine immune responses by co-immunization with CC-chemokine ligand 20 (CCL20) gene as immunoadjuvant

Plasmid DNA vaccination is a promising vaccine platform for prevention and treatment of infectious disease. Enhancement of the DNA vaccine potency by co-inoculation of immunoadjuvant has been shown to be an effective strategy. Modulation of dendritic cells and T-cells locomotion and trafficking to prime an immune response is mediated by distinct chemokines. The recent study was designed to elucidate the adjuvant activity of plasmid expressing CC-chemokine ligand 20 (pCCL20) in co-inoculation with hepatitis C virus (HCV) core DNA vaccine immunization. pCCL20 was constructed and evaluated for its functional expression. Sub-cutaneous inoculation of pCCL20 with HCV core DNA vaccine was performed via electroporation in BALB/c mice on day 0 and 14 and a HCV core protein booster was applied on day 28. On week after final immunization, both humoral and cell-mediated immune responses were assessed by indirect ELISA for core specific antibodies, lymphocyte proliferation, cytokine ELISA/ELISpot and cytotoxic Grenzyme B (GrzB) release assays. Mice were co-immunized with pCCL20 developed higher levels of core specific IFN-γ/IL-4 ratio and IL-2 release, IFN-γ producing cells, lymphocyte proliferation and cytotoxic Grenzyme B release in both draining lymph nodes and spleen cells of immunized mice. The core-specific serum total IgG and IgG2a/IgG1 ratio were significantly higher when the pCCL20 was co-inoculated. These results suggest the potential of CCL20 chemokine as vaccine adjuvant to enhance Th1 mediated cellular and humoral immune responses in HCV core DNA immunization.

Statistical linkage analysis of substitutions in patient-derived sequences of genotype 1a hepatitis C virus nonstructural protein 3 exposes targets for immunogen design

Chronic hepatitis C virus (HCV) infection is one of the leading causes of liver failure and liver cancer, affecting around 3% of the world's population. The extreme sequence variability of the virus resulting from error-prone replication has thwarted the discovery of a universal prophylactic vaccine. It is known that vigorous and multispecific cellular immune responses, involving both helper CD4(+) and cytotoxic CD8(+) T cells, are associated with the spontaneous clearance of acute HCV infection. Escape mutations in viral epitopes can, however, abrogate protective T-cell responses, leading to viral persistence and associated pathologies. Despite the propensity of the virus to mutate, there might still exist substitutions that incur a fitness cost. In this paper, we identify groups of coevolving residues within HCV nonstructural protein 3 (NS3) by analyzing diverse sequences of this protein using ideas from random matrix theory and associated methods. Our analyses indicate that one of these groups comprises a large percentage of residues for which HCV appears to resist multiple simultaneous substitutions. Targeting multiple residues in this group through vaccine-induced immune responses should either lead to viral recognition or elicit escape substitutions that compromise viral fitness. Our predictions are supported by published clinical data, which suggested that immune genotypes associated with spontaneous clearance of HCV preferentially recognized and targeted this vulnerable group of residues. Moreover, mapping the sites of this group onto the available protein structure provided insight into its functional significance. An epitope-based immunogen is proposed as an alternative to the NS3 epitopes in the peptide-based vaccine IC41.

IMPORTANCE

Despite much experimental work on HCV, a thorough statistical study of the HCV sequences for the purpose of immunogen design was missing in the literature. Such a study is vital to identify epistatic couplings among residues that can provide useful insights for designing a potent vaccine. In this work, ideas from random matrix theory were applied to characterize the statistics of substitutions within the diverse publicly available sequences of the genotype 1a HCV NS3 protein, leading to a group of sites for which HCV appears to resist simultaneous substitutions possibly due to deleterious effect on viral fitness. Our analysis leads to completely novel immunogen designs for HCV. In addition, the NS3 epitopes used in the recently proposed peptide-based vaccine IC41 were analyzed in the context of our framework. Our analysis predicts that alternative NS3 epitopes may be worth exploring as they might be more efficacious.