HCV Vaccine Research Articles

Bridging the gap: A new tool to down select HCV vaccine candidates.

Bridging the gap: A new tool to down select HCV vaccine candidates.

Recent approaches in clinical trials of hepatitis C virus vaccine, challenges and future directions

Globally HCV infects more than 170 million individuals and is a major risk of hepatocellular carcinoma, liver cirrhosis and transplantation. Recent antiviral therapy has significant side effects and is much expensive. During the early infection with HCV, the asymptomatic characteristics have a remarkable impact which results in unknowingly spreading HCV. Recently there is no effective vaccine available. Data indicate that a considerable proportion of individuals naturally manages HCV infection through immune feedback mechanisms, suggesting that developing an effective vaccine against HCV presents a reasonable challenge. Therefore, to control this deadly virus a prophylactic vaccine is compulsory. Different types of methods are adapted to design an effective HCV vaccine which are under different human clinical trials. The current review discusses the goals of the HCV vaccine, traditional vaccine methods, vaccine approaches and challenges in the development of vaccine design.

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

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

Inactivated genotype 1a, 2a and 3a HCV vaccine candidates induced broadly neutralising antibodies in mice

ObjectiveA prophylactic vaccine is needed to control the HCV epidemic, with genotypes 1–3 causing >80% of worldwide infections. Vaccine development is hampered by HCV heterogeneity, viral escape including protection of...

A pan-genotype hepatitis C virus viral vector vaccine generates T cells and neutralizing antibodies in mice.

A prophylactic vaccine targeting multiple HCV genotypes (gt) is urgently required to meet World Health Organization elimination targets. Neutralizing antibodies (nAbs) and CD4+ and CD8+ T cells are associated with spontaneous clearance of HCV, and each may contribute to protective immunity. However, current vaccine candidates generate either nAbs or T cells targeting genetically variable epitopes and have failed to show efficacy in human trials. We have previously shown that a simian adenovirus vector (ChAdOx1) encoding conserved sequences across gt1-6 (ChAd-Gt1-6), and separately gt-1a E2 protein with variable regions deleted (E2Δ123HMW ), generates pan-genotypic T cells and nAbs, respectively. We now aim to develop a vaccine to generate both viral-specific B- and T-cell responses concurrently. We show that vaccinating with ChAd-Gt1-6 and E2Δ123HMW sequentially in mice generates T-cell and antibody (Ab) responses comparable to either vaccine given alone. We encoded E2Δ123 in ChAdOx1 (ChAd-E2Δ123) and show that this, given with an E2Δ123HMW protein boost, induces greater CD81-E2 inhibitory and HCV-pseudoparticle nAb titers compared to the E2Δ123HMW prime boost. We developed bivalent viral vector vaccines (ChAdOx1 and modified vaccinia Ankara [MVA]) encoding both Gt1-6 and E2Δ123 immunogens (Gt1-6-E2Δ123) generating polyfunctional CD4+ and CD8+ T cells and nAb titers in prime/boost strategies. This approach generated nAb responses comparable to monovalent E2Δ123 ChAd/MVA vaccines and superior to three doses of recombinant E2Δ123HMW protein, while also generating high-magnitude T-cell responses. These data are an important step forward for the development of a pan-genotype HCV vaccine to elicit T cells and nAbs for future assessment in humans.

Neutralization and receptor use of infectious culture-derived rat hepacivirus as a model for HCV.

Lack of tractable immunocompetent animal models amenable to robust experimental challenge impedes vaccine efforts for HCV. Infection with rodent hepacivirus from Rattus norvegicus (RHV-rn1) in rats shares HCV-defining characteristics, including liver tropism, chronicity, and pathology. RHV in vitro cultivation would facilitate genetic studies on particle production, host factor interactions, and evaluation of antibody neutralization guiding HCV vaccine approaches. We report an infectious reverse genetic cell culture system for RHV-rn1 using highly permissive rat hepatoma cells and adaptive mutations in the E2, NS4B, and NS5A viral proteins. Cell culture-derived RHV-rn1 particles (RHVcc) share hallmark biophysical characteristics of HCV and are infectious in mice and rats. Culture adaptive mutations attenuated RHVcc in immunocompetent rats, and the mutations reverted following prolonged infection, but not in severe combined immunodeficiency (SCID) mice, suggesting that adaptive immune pressure is a primary driver of reversion. Accordingly, sera from RHVcc-infected SCID mice or the early acute phase of immunocompetent mice and rats were infectious in culture. We further established an in vitro RHVcc neutralization assay, and observed neutralizing activity of rat sera specifically from the chronic phase of infection. Finally, we found that scavenger receptor class B type I promoted RHV-rn1 entry in vitro and in vivo. The RHV-rn1 infectious cell culture system enables studies of humoral immune responses against hepacivirus infection. Moreover, recapitulation of the entire RHV-rn1 infectious cycle in cell culture will facilitate reverse genetic studies and the exploration of tropism and virus-host interactions.

From the Editor’s Desk...

From the Editor’s Desk...

SEROPREVALENCE OF HEPATITIS-C VIRUS AMONG MAINTENANCE HEMODIALYSIS PATIENTS AT TERTIARY CARE HOSPITAL IN WESTERN RAJASTHAN

Introduction: Hepatitis C virus infection in one of the blood borne infections that patients on maintenance hemodialysis acquire during the course of hemodialysis. The patients on hemodialysis develop viral hepatitis and also there is no vaccine for HCV, therefore it becomes crucial to early diagnose and start anti-viral therapy among these patients. Methods:All patients were tested for anti-HCV antibody by using Merilisa HCV ELISAkit Results: In this study a total of 109 patients were recruited. Out of 109, 64(58.7%) were males and 45(41.3%) were females. Majority of the patients 42(38.5%) were in 41-60 years age group. A total of 35.8% patients were tested positive for anti-HCV antibody by ELISA. Among seropositive patients highest positivity (53.8%) was found among 41-60 years age group. Conclusion: HCV positivity was found to be associated with duration of dialysis. Majority of the HCV positive patients belonged to 41-60 years age group.

Evolutionary modeling reveals enhanced mutational flexibility of HCV subtype 1b compared with 1a

SummaryHepatitis C virus (HCV) is a leading cause of liver-associated disease and liver cancer. Of the major HCV subtypes, patients infected with subtype 1b have been associated with having a higher risk of developing chronic infection and hepatocellular carcinoma. However, underlying reasons for this increased disease severity remain unknown. Here, we provide an evolutionary rationale, based on a comparative study of fitness landscape and in-host evolutionary models of the E2 glycoprotein of HCV subtypes 1a and 1b. Our analysis demonstrates that a higher chronicity rate of 1b may be attributed to lower fitness constraints, enabling 1b viruses to more easily escape antibody responses. More generally, our results suggest that differences in evolutionary constraints between HCV subtypes may be an important factor in mediating distinct disease outcomes. Our analysis also identifies antibodies that appear escape-resistant against both subtypes 1a and 1b, providing directions for designing HCV vaccines having cross-subtype protection.

Hepatitis C virus DNA vaccines: a systematic review

BackgroundVaccination against HCV is an effective measure in reduction of virus-related public health burden and mortality. However, no prophylactic vaccine is available as of yet. DNA-based immunization is a promising modality to generate cellular and humoral immune responses. The objective of this study is to provide a systematic review of HCV DNA vaccines and investigate and discuss the strategies employed to optimize their efficacies.MethodsMEDLINE (PubMed), Web of Science, Scopus, ScienceDirect, and databases in persian language including the Regional Information Centre for Science & Technology (RICeST), the Scientific Information Database and the Iranian Research Institute for Information Science and Technology (IranDoc) were examined to identify studies pertaining to HCV nucleic acid vaccine development from 2000 to 2020.ResultsTwenty-seven articles were included. Studies related to HCV RNA vaccines were yet to be published. A variety of strategies were identified with the potential to optimize HCV DNA vaccines such as incorporating multiple viral proteins and molecular tags such as HBsAg and Immunoglobulin Fc, multi-epitope expression, co-expression plasmid utilization, recombinant subunit immunogens, heterologous prime-boosting, incorporating NS3 mutants in DNA vaccines, utilization of adjuvants, employment of less explored methods such as Gene Electro Transfer, construction of multi- CTL epitopes, utilizing co/post translational modifications and polycistronic genes, among others. The effectiveness of the aforementioned strategies in boosting immune response and improving vaccine potency was assessed.ConclusionsThe recent progress on HCV vaccine development was examined in this systematic review to identify candidates with most promising prophylactic and therapeutic potential.

Incorporation of apolipoprotein E into HBV–HCV subviral envelope particles to improve the hepatitis vaccine strategy

Hepatitis C is a major threat to public health for which an effective treatment is available, but a prophylactic vaccine is still needed to control this disease. We designed a vaccine based on chimeric HBV–HCV envelope proteins forming subviral particles (SVPs) that induce neutralizing antibodies against HCV in vitro. Here, we aimed to increase the neutralizing potential of those antibodies, by using HBV–HCV SVPs bearing apolipoprotein E (apoE). These particles were produced by cultured stable mammalian cell clones, purified and characterized. We found that apoE was able to interact with both chimeric HBV–HCV (E1-S and E2-S) proteins, and with the wild-type HBV S protein. ApoE was also detected on the surface of purified SVPs and improved the folding of HCV envelope proteins, but its presence lowered the incorporation of E2-S protein. Immunization of New Zealand rabbits resulted in similar anti-S responses for all rabbits, whereas anti-E1/-E2 antibody titers varied according to the presence or absence of apoE. Regarding the neutralizing potential of these anti-E1/-E2 antibodies, it was higher in rabbits immunized with apoE-bearing particles. In conclusion, the association of apoE with HCV envelope proteins may be a good strategy for improving HCV vaccines based on viral envelope proteins.

Prediction of Multi-Epitopic Domains of a Putative Oral Vaccine against Hepatitis C Virus

For vaccine development, triggering an immune response is desired. Designing and assessing vaccine candidates for the appropriate immune response is critical for their success. Hepatitis C virus is the major cause of liver disease. Anti HCV vaccines if designed is rational decision to reinforce specific T-cell as a crucial aspect of effective antiviral treatment. This study explored the use of bioinformatics tools by retrieval of twenty (20) HCV proteins which were selected for vaccine design. These were retrieved from UniProt server based on their antigenicity, virulence, subcellular localization, essentiality non-homology and other physical parameters, including, TM helices, and relative molecular mass. BLASTp revealed 80% non-identity with Homo sapiens genes. The Epitopes obtained include: Q3S781_9HEPC52-71, POLG_HCVBK442-461, POLG_HCVJA2-21, POLG_HCVJ177-95, POLG_HCVCO445-464, POLG_HCVR61107-1126, POLG_HCVJP47-66, POLG_HCVTW664-683, POLG_HCVTR446-465, LTOR5_HUMAN23-42, POLG_HCVT5100-119, POLG_HCVJT77-96, HOIL1_HUMAN169-188, POLG_HCVJ4644-663, POLG_HCVJ847-66, TFB2M_HUMAN49-68, RSF1_HUMAN138-157, A8DGK3_9HEPC77-96, A8DHN1_9HEPC54-73, and A8DFL0_9HEPC2-21. An antigenicity score of 0.6004 was obtained with the use of VaxiJen server. The allergenicity prediction showed that the vaccine is not allergenic with the use of AllerTOP v.2.0 and AlgPred servers. The molecular weights and theoretical pI of protein were 45.1 kDa and 10.24 kDa respectively. A potentially suitable vaccine candidate with multivariant regions and immunogenic which could be antagonistic to HCV was designed.

Seroprevalence of Chlamydia trachomatis, herpes simplex 2, Epstein-Barr virus, hepatitis C and associated factors among a cohort of men ages 18-70 years from three countries.

To estimate the seroprevalence of Chlamydia trachomatis (CT), herpes simplex type-2 (HSV2), hepatitis C (HCV), Epstein-Barr virus (EBV) and nine human papilloma virus (HPV) types, and investigated factors associated with the seropositivity among men from three countries (Brazil, Mexico and U.S). Archived serum specimens collected at enrollment for n = 600 men were tested for antibodies against CT, HSV2, HCV, EBV, and 9-valent HPV vaccine types (6/11/16/18/31/33/45/52/58) using multiplex serologic assays. Socio-demographic, lifestyle and sexual behavior data at enrollment were collected through a questionnaire. Overall, 39.3% of the men were seropositive for CT, 25.4% for HSV2, 1.3% for HCV, 97.3% for EBV, 14.0% for at least one of the seven oncogenic HPV (types: 16/18/31/33/45/52/58), and 17.4% for HPV 6/11. In the unadjusted models, age, race, smoking, sexual behavior variables, and seropositivity for high-risk HPV were significantly associated with the seropositivity for CT. In multivariable analyses, self-reported black race, higher numbers of lifetime female/male sexual partners, current smoking, and seropositivity to high-risk HPV were significantly associated with increased odds of CT seropositivity. Odds of HSV2 seroprevalence were elevated among older men and those seropositive for high risk HPV. Exposure to STIs is common among men. Prevention and screening programs should target high-risk groups to reduce the disease burden among men, and to interrupt the disease transmission to sexual partners.

Pathogenesis, MicroRNA-122 Gene-Regulation, and Protective Immune Responses After Acute Equine Hepacivirus Infection.

Background and AimsEquine hepacivirus (EqHV) is phylogenetically the closest relative of HCV and shares genome organization, hepatotropism, transient or persistent infection outcome, and the ability to cause hepatitis. Thus, EqHV studies are important to understand equine liver disease and further as an outbred surrogate animal model for HCV pathogenesis and protective immune responses. Here, we aimed to characterize the course of EqHV infection and associated protective immune responses.Approach and ResultsSeven horses were experimentally inoculated with EqHV, monitored for 6 months, and rechallenged with the same and, subsequently, a heterologous EqHV. Clearance was the primary outcome (6 of 7) and was associated with subclinical hepatitis characterized by lymphocytic infiltrate and individual hepatocyte necrosis. Seroconversion was delayed and antibody titers waned slowly. Clearance of primary infection conferred nonsterilizing immunity, resulting in shortened duration of viremia after rechallenge. Peripheral blood mononuclear cell responses in horses were minimal, although EqHV‐specific T cells were identified. Additionally, an interferon‐stimulated gene signature was detected in the liver during EqHV infection, similar to acute HCV in humans. EqHV, as HCV, is stimulated by direct binding of the liver‐specific microRNA (miR), miR‐122. Interestingly, we found that EqHV infection sequesters enough miR‐122 to functionally affect gene regulation in the liver. This RNA‐based mechanism thus could have consequences for pathology.ConclusionsEqHV infection in horses typically has an acute resolving course, and the protective immune response lasts for at least a year and broadly attenuates subsequent infections. This could have important implications to achieve the primary goal of an HCV vaccine; to prevent chronicity while accepting acute resolving infection after virus exposure.

To Include or Occlude: Rational Engineering of HCV Vaccines for Humoral Immunity.

Direct-acting antiviral agents have proven highly effective at treating existing hepatitis C infections but despite their availability most countries will not reach the World Health Organization targets for elimination of HCV by 2030. A prophylactic vaccine remains a high priority. Whilst early vaccines focused largely on generating T cell immunity, attention is now aimed at vaccines that generate humoral immunity, either alone or in combination with T cell-based vaccines. High-resolution structures of hepatitis C viral glycoproteins and their interaction with monoclonal antibodies isolated from both cleared and chronically infected people, together with advances in vaccine technologies, provide new avenues for vaccine development.

Complete genome analysis identifies recombinant events and positive selection sites of hepatitis C virus from mainland China during 2010–2019

Identification of new recombinant HCV strains and positive selection sites are crucially important for the formulation of virus intervention measures. However, little is known about the recombinant variant information and positive selection sites of circulating HCV strains in mainland China. In this study, we systematically identified recombinant variants and positive selection sites of HCV in mainland China during the 2010–2019. Phylogenetic analysis results indicated that HCV-6 was one of the dominant genotypes in mainland China during 2010–2019, whereas genotypes 7 and 8 were not detected. Recombinant analysis based on 102 full-length genome sequences of Chinese epidemic strains of HCV identified four intra-genotypic recombinants (strains WYHCV286, GB28, GZ2983, and HCV156) and one inter-genotypic recombinant (strain HH075). Specifically, two breakpoints in the 5′ UTR of two recombinants, the strains HH075 and WYHCV286, are rather unusual and has not been described before. Further, selection pressure analyses revealed five positive selective sites, which were located in the core, E2, and NS5B protein. Notably, positive selective sites in NS5B and core protein may be partially responsible for the drug resistance and immune evasion. To the best of our knowledge, this study firstly reported five specific intertypic and intratypic recombinants of Chinese epidemic strains of HCV, which highlight their significance for anti−HCV treatment and vaccine development.

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.

Forward stepwise logistic regression approach for determinants of hepatitis B & C among Hiv/Aids patients

Hepatitis-related liver diseases are a leading cause of mortality and morbidity among people with HIV/ AIDS taking highly active antiretroviral therapy due to shared transmission routes. An estimated 2–4 million HIV-infected persons have chronic HBV co-infection, and 4–5 million have HCV co-infection worldwide and 14,000 new infections each day. The purpose of this study was to determine the prevalence and associated factors of HBV and HCV co-infection in HIV-positive patients. A cross-sectional study was conducted among 235 HIV/ AIDS patients seeking medical care at special clinics of two public hospitals in Lahore, Pakistan, from February 2018 to May 2018. A structured questionnaire was used to collect information on socio-demographic and clinical characteristics of HIV/ AIDS patients after obtaining their written informed consent. Chi-square, Fisher's exact, and two independent sample t-tests as appropriate were used to find the association between risk factors and HBV, HCV co-infection with HIV. Further, a forward stepwise logistic regression model was used to evaluate the predictors of HBV and HCV co-infection with HIV. P-value < 0.05 was regarded as significant. Of 235 HIV-positive patients, 9% were co-infected with HBV, 41 were HCV co-infected, and 6% had HBV-HCV triple infection. The highest prevalence of HBV (55%), HCV co-infection (70%), and HBV-HCV triple infection (85%) were observed in intravenous drug users followed by heterosexual routes. Male, hypertensive, alcohol consumers, and smokers were statistically significantly associated with HBV co-infection $(P-value < 0.05)$. The factors include being male, never married, having $< 1$ year of HIV diagnosis, having $< 200$ CD4 counts (cell/mm3), presence of physical disability, having been infected through sexual routes, injecting drug user, alcohol consumer, and smoker were statistically significantly associated with HCV co-infection $(P-value < 0.05)$. Whereas the factors; heterosexual transmission, intravenous drug use, alcohol use, smoking, and presence of physical disability were statistically significantly associated with HBV, HCV triple infection $(P < 0.05)$. The adjusted odds ratio obtained by fitted logistic regression model showed that HIV transmission routes (both hetero and homo) and never married had lesser odds of HCV co-infection whereas the person with HIV transmission through intravenous drug use, who smoke and aged more than 30 years, had greater odds of HCV co-infection. Co-infection with hepatitis B and C virus is common among this studied sample of HIV-infected patients. The study's finding reaffirms the need for routine baseline screening for this marker and as there is more chance of co-infection with these hepatitis viruses due to enhanced immunodeficiency by HIV and shared routes of transmission. It highlights the need for timely initiation of HAART. Furthermore, those found to be negative should be immunized with HBV and HCV vaccines to improve.

Hepatitis C reference viruses highlight potent antibody responses and diverse viral functional interactions with neutralising antibodies

ObjectiveNeutralising antibodies are key effectors of infection-induced and vaccine-induced immunity. Quantification of antibodies’ breadth and potency is critical for understanding the mechanisms of protection and for prioritisation of vaccines. Here,...

Structure-Based Design of Hepatitis C Virus E2 Glycoprotein Improves Serum Binding and Cross-Neutralization.

An effective vaccine for hepatitis C virus (HCV) is a major unmet need, and it requires an antigen that elicits immune responses to key conserved epitopes. Based on structures of antibodies targeting HCV envelope glycoprotein E2, we designed immunogens to modulate the structure and dynamics of E2 and favor induction of broadly neutralizing antibodies (bNAbs) in the context of a vaccine. These designs include a point mutation in a key conserved antigenic site to stabilize its conformation, as well as redesigns of an immunogenic region to add a new N-glycosylation site and mask it from antibody binding. Designs were experimentally characterized for binding to a panel of human monoclonal antibodies (HMAbs) and the coreceptor CD81 to confirm preservation of epitope structure and preferred antigenicity profile. Selected E2 designs were tested for immunogenicity in mice, with and without hypervariable region 1, which is an immunogenic region associated with viral escape. One of these designs showed improvement in polyclonal immune serum binding to HCV pseudoparticles and neutralization of isolates associated with antibody resistance. These results indicate that antigen optimization through structure-based design of the envelope glycoproteins is a promising route to an effective vaccine for HCV.IMPORTANCE Hepatitis C virus infects approximately 1% of the world's population, and no vaccine is currently available. Due to the high variability of HCV and its ability to actively escape the immune response, a goal of HCV vaccine design is to induce neutralizing antibodies that target conserved epitopes. Here, we performed structure-based design of several epitopes of the HCV E2 envelope glycoprotein to engineer its antigenic properties. Designs were tested in vitro and in vivo, demonstrating alteration of the E2 antigenic profile in several cases, and one design led to improvement of cross-neutralization of heterologous viruses. This represents a proof of concept that rational engineering of HCV envelope glycoproteins can be used to modulate E2 antigenicity and optimize a vaccine for this challenging viral target.