Vaccines targeting preS1 domain overcome immune tolerance in hepatitis B virus carrier mice

Mutations in the S gene of hepatitis B virus in three generations of patients with chronic hepatitis B

Failure to neutralize HBsAg and subsequent escape from the host immune system may be caused by HBsAg mutations, particularly in the "a" determinant, which alters the antigenicity of the protein. The purpose of this study was to examine the frequency of S gene mutations in three generations of HBV cases in northeastern Iran. In this study, 90 patients with chronic HBV were assigned to three groups according to the inclusion criteria. The plasma were utilized to extract viral DNA, and the PCR was applied. Direct sequencing and alignment were performed on the S gene, using reference sequence. The results indicated that all HBV genomes were categorized as the genotype D/ayw2. Among 79 point mutations detected, 36.8% were silent, and 56.2% were missense. In the S region, mutations were observed in 88.9% of CHB subjects studied. In the three-generation group, 21.5% of mutations were in the "a" determinant, and 2.6%, 19.5%, and 87.0% of these mutations were observed in antigenic epitopes of CTLs, CD4+, and B cells, respectively. In addition, 56.7% of mutations occurred at Major Hydrophilic Region. S143L and G145R mutations which the most prevalent in the three-generation (36.7%, 20%), and two-generation (42.5%, 20%) groups, related to the failure of HBsAg detection, vaccine, and immunotherapy escape. The findings showed that most of the mutations were concentrated in the B cell epitope. Most CHB cases from the three-generation, especially grandmothers, had HBV S gene mutations and subsequent amino acid mutations, suggesting that these mutations may be critical for pathogenesis and vaccine evasion.

Engineered anti-PDL1 with IFNα targets both immunoinhibitory and activating signals in the liver to break HBV immune tolerance

OBJECTIVE

The purpose of this study is to develop an anti-PDL1-based interferon (IFN) fusion protein to overcome the chronic hepatitis B virus (HBV)-induced immune tolerance, and combine this immunotherapy with a HBV vaccine to achieve the functional cure of chronic hepatitis B (CHB) infection.

DESIGN

We designed an anti-PDL1-IFNα heterodimeric fusion protein, in which one arm was derived from anti-PDL1 antibody and the other arm was IFNα, to allow targeted delivery of IFNα into the liver by anti-PDL1 antibody. The effect of the anti-PDL1-IFNα heterodimer on overcoming hepatitis B surface antigen (HBsAg) vaccine resistance was evaluated in chronic HBV carrier mice.

RESULTS

The anti-PDL1-IFNα heterodimer preferentially targeted the liver and resulted in viral suppression, the PD1/PDL1 immune checkpoint blockade and dendritic cell activation/antigen presentation to activate HBsAg-specific T cells, thus breaking immune tolerance in chronic HBV carrier mice. When an HBsAg vaccine was administered soon after anti-PDL1-IFNα heterodimer treatment, we observed strong anti-HBsAg antibody and HBsAg-specific T cell responses for efficient HBsAg clearance in chronic HBV carrier mice that received the combination treatment but not in those that received either single treatment.

CONCLUSIONS

Targeting the liver with an engineered anti-PDL1-IFNα heterodimer can break HBV-induced immune tolerance to an HBsAg vaccine, offering a promising translatable therapeutic strategy for the functional cure of CHB.

The Multiple Facets and Disorders of B Cell Functions in Hepatitis B Virus Infection

Chronic hepatitis B virus (HBV) infection continues to be a global public health burden. B cells play a pivotal role in mediating HBV clearance and can participate in the development of anti-HBV adaptive immune responses through multiple mechanisms, such as antibody production, antigen presentation, and immune regulation. However, B cell phenotypic and functional disorders are frequently observed during chronic HBV infection, suggesting the necessity of targeting the disordered anti-HBV B cell responses to design and test new immune therapeutic strategies for the treatment of chronic HBV infection. In this review, we provide a comprehensive summary of the multiple roles of B cells in mediating HBV clearance and pathogenesis as well as the latest developments in understanding the immune dysfunction of B cells in chronic HBV infection. Additionally, we discuss novel immune therapeutic strategies that aim to enhance anti-HBV B cell responses for curing chronic HBV infection.

Induction of a strong and long-lasting neutralizing immune response by dPreS1-TLR2 agonist nanovaccine against hepatitis B virus

Hepatitis B virus remains a major medical burden with more than 250 million chronically infected patients worldwide and 900,000 deaths each year, due to the disease progression towards severe complications (cirrhosis, hepatocellular carcinoma). Despite the availability of a prophylactic vaccine, this infection is still pandemic in Western Pacific and African regions, where around 6% of the adult population is infected. Among novel anti-HBV strategies, innovative drug delivery systems, such as nanoparticle platforms to deliver vaccine antigens or therapeutic molecules have been investigated. Here, we developed polylactic acid-based biodegradable nanoparticles as an innovative and efficient vaccine. They are twice functionalized by (i) the entrapment of Pam₃CSK₄, an immunomodulator and ligand to Toll-Like-Receptor 1/2, and by (ii) the adsorption/coating of myristoylated (2-48) derived PreS1 from the HBV surface antigen, identified as the major viral attachment site on hepatocytes. We demonstrate that such formulations mimic HBV virion with an efficient peptide recognition by the immune system, and elicit potent and durable antibody responses in naive mice during at least one year. We also show that the most efficient in vitro viral neutralization was observed with NP-Pam₃CSK₄-dPreS1 sera. The immunogenicity of the derived HBV antigen is modulated by the likely synergistic action of both the dPreS1 coated nanovector and the adjuvant moiety. This formulation represents a promising vaccine alternative to fight HBV infection.

Optimized Cationic Lipid-assisted Nanoparticle for Delivering CpG Oligodeoxynucleotides to Treat Hepatitis B Virus Infection

PURPOSE

Hepatitis B virus (HBV) infection is such a global health problem that hundreds of millions of people are HBV carriers. Current anti-viral agents can inhibit HBV replication, but can hardly eradicate HBV. Cytosine-phosphate-guanosine (CpG) oligodeoxynucleotides (ODNs) are an adjuvant that can activate plasmacytoid dendritic cells (pDCs) and conventional dendritic cells (cDCs) to induce therapeutic immunity for HBV eradication. However, efficient delivery of CpG ODNs into pDCs and cDCs remains a challenge. In this study, we constructed a series of cationic lipid-assisted nanoparticles (CLANs) using different cationic lipids to screen an optimal nanoparticle for delivering CpG ODNs into pDCs and cDCs.

METHODS

We constructed different CLAN_CpG using six cationic lipids and analyzed the cellular uptake of different CLAN_CpG by pDCs and cDCs in vitro and in vivo, and further analyzed the efficiency of different CLAN_CpG for activating pDCs and cDCs in both wild type mice and HBV-carrier mice.

RESULTS

We found that CLAN fabricated with 1,2-Dioleoyl-3-trimethylammonium propane (DOTAP) showed the highest efficiency for delivering CpG ODNs into pDCs and cDCs, resulting in strong therapeutic immunity in HBV-carrier mice. By using CLAN_CpG as an immune adjuvant in combination with the injection of recombinant hepatitis B surface antigen (rHBsAg), HBV was successfully eradicated and the chronic liver inflammation in HBV-carrier mice was reduced.

CONCLUSION

We screened an optimized CLAN fabricated with DOTAP for efficient delivery of CpG ODNs to pDCs and cDCs, which can act as a therapeutic vaccine adjuvant for treating HBV infection.

Hepatitis B Therapeutic Vaccine: A Patent Review

Viral hepatitis has long been underrated as a danger to global health. The UN only recently called for worldwide action to tackle viral hepatitis and lessen the disease burden in its "2030 Agenda for Sustainable Development". Hepatitis B virus (HBV), which causes liver cirrhosis and malignancy, is a main cause of death globally. This review analyses innovative HBV therapeutic vaccine candidates for which a patent was filed between January 2010 and March 2022 and presents future improvement techniques for vaccine efficacy. Although there is a preventative vaccine for HBV infection, over 3% of people worldwide have the disease on a long-term basis and can no longer benefit from it. Most people will have chronic HBV infection for the rest of their lives once it has been diagnosed. Moreover, only a small percentage of treated patients experience a functional cure with persistent hepatitis B surface antigen reduction. A significant proportion of deaths are caused by liver cirrhosis and hepatocellular cancer, which are both caused by chronic hepatitis B infection. Hence, there is an urgent need for novel medications due to the inadequacies of the current therapies.

Cholesterol accumulation on dendritic cells reverses chronic hepatitis B virus infection-induced dysfunction

Chronic hepatitis B (CHB) infection remains a serious public health problem worldwide; however, the relationship between cholesterol levels and CHB remains unclear. We isolated peripheral blood mononuclear cells from healthy blood donors and CHB patients to analyze free cholesterol levels, lipid raft formation, and cholesterol metabolism-related pathways. Hepatitis B virus (HBV)-carrier mice were generated and used to confirm changes in cholesterol metabolism and cell-surface lipid raft formation in dendritic cells (DCs) in the context of CHB. Additionally, HBV-carrier mice were immunized with a recombinant HBV vaccine (rHBVvac) combined with lipophilic statins and evaluated for vaccine efficacy against HBV. Serum samples were analyzed for HBsAg, anti-HBs, and alanine aminotransferase levels, and liver samples were evaluated for HBV DNA and RNA and HBcAg. CHB reduced free cholesterol levels and suppressed lipid raft formation on DCs in patients with CHB and HBV-carrier mice, whereas administration of lipophilic statins promoted free cholesterol accumulation and restored lipid rafts on DCs accompanied by an enhanced antigen-presentation ability in vitro and in vivo. Cholesterol accumulation on DCs improved the rHBVvac-mediated elimination of serum HBV DNA and intrahepatic HBV DNA, HBV RNA, and HBcAg and promoted the rHBVvac-mediated generation and polyfunctionality of HBV-specific CD11ahi CD8αlo cells, induction of the development of memory responses against HBV reinfection, and seroconversion from HBsAg to anti-HBs. The results demonstrated the important role of cholesterol levels in DC dysfunction during CHB, suggesting that strategies to increase cholesterol accumulation on DCs might enhance therapeutic vaccine efficacy against HBV and support development toward clinical CHB treatment.

Novel prime-boost immune-based therapy inhibiting both hepatitis B and D virus infections

OBJECTIVE

Chronic HBV/HDV infections are a major cause of liver cancer. Current treatments can only rarely eliminate HBV and HDV. Our previously developed preS1-HDAg immunotherapy could induce neutralising antibodies to HBV in vivo and raise HBV/HDV-specific T-cells. Here, we further investigate if a heterologous prime-boost strategy can circumvent T-cell tolerance and preclude HDV superinfection in vivo.

DESIGN

A DNA prime-protein boost strategy was evaluated for immunogenicity in mice and rabbits. Its ability to circumvent T-cell tolerance was assessed in immunocompetent hepatitis B surface antigen (HBsAg)-transgenic mice. Neutralisation of HBV and HDV was evaluated both in vitro and in immunodeficient human-liver chimeric mice upon adoptive transfer.

RESULTS

The prime-boost strategy elicits robust HBV/HDV-specific T-cells and preS1-antibodies that can effectively prevent HBV and HDV (co-)infection in vitro and in vivo. In a mouse model representing the chronic HBsAg carrier state, active immunisation primes high levels of preS1-antibodies and HDAg-specific T-cells. Moreover, transfer of vaccine-induced antibodies completely protects HBV-infected human-liver chimeric mice from HDV superinfection.

CONCLUSION

The herein described preS1-HDAg immunotherapy is shown to be immunogenic and vaccine-induced antibodies are highly effective at preventing HBV and HDV (super)infection both in vitro and in vivo. Our vaccine can complement current and future therapies for the control of chronic HBV and HDV infection.

Efficient cellular and humoral immune response and production of virus-neutralizing antibodies by the Hepatitis B Virus S/preS116-42 antigen

Despite the availability of improved antiviral therapies, infection with Hepatitis B virus (HBV) remains a3 significant health issue, as a curable treatment is yet to be discovered. Current HBV vaccines relaying on the efficient expression of the small (S) envelope protein in yeast and the implementation of mass vaccination programs have clearly contributed to containment of the disease. However, the lack of an efficient immune response in up to 10% of vaccinated adults, the controversies regarding the seroprotection persistence in vaccine responders and the emergence of vaccine escape virus mutations urge for the development of better HBV immunogens. Due to the critical role played by the preS1 domain of the large (L) envelope protein in HBV infection and its ability to trigger virus neutralizing antibodies, including this protein in novel vaccine formulations has been considered a promising strategy to overcome the limitations of S only-based vaccines. In this work we aimed to combine relevant L and S epitopes in chimeric antigens, by inserting preS1 sequences within the external antigenic loop of S, followed by production in mammalian cells and detailed analysis of their antigenic and immunogenic properties. Of the newly designed antigens, the S/preS1^16–42 protein assembled in subviral particles (SVP) showed the highest expression and secretion levels, therefore, it was selected for further studies in vivo. Analysis of the immune response induced in mice vaccinated with S/preS1^16–42- and S-SVPs, respectively, demonstrated enhanced immunogenicity of the former and its ability to activate both humoral and cellular immune responses. This combined activation resulted in production of neutralizing antibodies against both wild-type and vaccine-escape HBV variants. Our results validate the design of chimeric HBV antigens and promote the novel S/preS1 protein as a potential vaccine candidate for administration in poor-responders to current HBV vaccines.

Novel therapeutic strategies for Chronic Hepatitis B

The last few years have seen a resurgence of activity in the hepatitis B drug pipeline, with many compounds in various stages of development. This review aims to provide a comprehensive overview of the latest advances in therapeutics for chronic hepatitis B (CHB). We will discuss the broad spectrum of direct-acting antivirals in clinical development, including capsids inhibitors, siRNA, HBsAg and polymerase inhibitors. In addition, host-targeted therapies (HTT) will be extensively reviewed, focusing on the latest progress in immunotherapeutics such as toll-like receptors and RIG-1 agonists, therapeutic vaccines and immune checkpoints modulators. A growing number of HTT in pre-clinical development directly target the key to HBV persistence, namely the covalently closed circular DNA (cccDNA) and hold great promise for HBV cure. This exciting area of HBV research will be highlighted, and molecules such as cyclophilins inhibitors, APOBEC3 deaminases and epigenetic modifiers will be discussed.

Viral Hepatitis - The Road Traveled and the Journey Remaining

Hepatitis is defined as inflammation of the liver and is commonly due to infection with The hepatotropic viruses - hepatitis A, B, C, D and E. Hepatitis carries one of the highest disease burdens globally and has caused significant morbidity and mortality among different patient populations. Clinical presentation varies from asymptomatic or acute flu-like illness to acute liver failure or chronic liver disease, characterized by jaundice, hepatomegaly and ascites among many other signs. Eventually, this can lead to fibrosis (cirrhosis) of the liver parenchyma and carries a risk of development into hepatocellular carcinoma. Hepatitis B and C are most notorious for causing liver cirrhosis; in 2019, an estimated 296 million people worldwide had chronic hepatitis B infection and 58 million are currently estimated to have chronic hepatitis C, with 1.5 million new infections of both hepatitis B and C, occurring annually. With the help of latest serological biomarkers and viral nucleic acid amplification tests, it has become rather simple to efficiently screen, diagnose and monitor patients with hepatitis, and to commence with appropriate antiviral treatment. More importantly, the development of vaccinations against some of these viruses has greatly helped to curb the infection rates. Whilst there has been exceptional progress over the years in the management of viral hepatitis, many hurdles still remain which must be addressed in order to proceed towards a hepatitis-free world. This review will shed light on the origin and discovery of the hepatitis viruses, the global epidemiology and clinical symptoms, diagnostic modalities, currently available treatment options, the importance of prevention, and the journey needed to move forward towards the eradication of its global disease burden.

CpG-C ODN M362 as an immunoadjuvant for HBV therapeutic vaccine reverses the systemic tolerance against HBV

Chronic Hepatitis B virus (CHB) infection is a global public health problem. Oligodeoxynucleotides (ODNs) containing class C unmethylated cytosine-guanine dinucleotide (CpG-C) motifs may provide potential adjuvants for the immunotherapeutic strategy against CHB, since CpG-C ODNs stimulate both B cell and dendritic cell (DC) activation. However, the efficacy of CpG-C ODN as an anti-HBV vaccine adjuvant remains unclear. In this study, we demonstrated that CpG M362 (CpG-C ODN) as an adjuvant in anti-HBV vaccine (cHBV-vaccine) successfully and safely eliminated the virus in HBV-carrier mice. The cHBV-vaccine enhanced DC maturation both in vivo and in vitro, overcame immune tolerance, and recovered exhausted T cells in HBV-carrier mice. Furthermore, the cHBV-vaccine elicited robust hepatic HBV-specific CD8⁺ and CD4⁺ T cell responses, with increased cellular proliferation and IFN-γ secretion. Additionally, the cHBV-vaccine invoked a long-lasting follicular CXCR5⁺ CD8⁺ T cell response following HBV re-challenge. Taken together, CpG M362 in combination with rHBVvac cleared persistent HBV and achieved long-term virological control, making it a promising candidate for treating CHB.

An Overview of the Current Hepatitis B Treatment Strategies after Liver Transplantation

Currently, liver transplantation (LT) is considered as the only option for the treatment of patients with various causes of liver failure, including patients with chronic hepatitis B virus (HBV) infections. Overall, patients with HBV who undergo LT are at increased risk of hepatitis B infection recurrence. Although the current knowledge regarding the pathophysiology of this infection has been dramatically increased over the past few decades, it is still considered a complex disease process with varying degrees of clinical characteristics and changing patterns over time. There are various treatment strategies for preventing HBV recurrence in the LT setting. Generally, these regimens include oral nucleoside/ nucleotide analogues (NAs), hepatitis B immune globulin (HBIG), and vaccines or the combination of these drugs. The treatment strategy of choice should be based on cost-effectiveness, along with other patients underlying conditions. In this case, studies indicate that potent NAs are more cost-effective than HBIG in most case scenarios. In this article, we aimed to review the general medications used in the prophylaxis of the recurrence of HBV infection after LT.

Immunotherapy and therapeutic vaccines for chronic HBV infection

Chronic hepatitis B virus (HBV) infection is a major global health burden causing severe complications like liver cirrhosis or hepatocellular carcinoma. Curative treatment options are lacking. Therefore, there is an urgent need for new therapeutic options. Immunotherapy with the goal to restore dysfunctional HBV-specific T cell immunity is an interesting new therapeutic strategy. Based on current evidence on dysfunction of the HBV-specific CD8⁺ T cell response in chronic HBV infection, we will review the growing field of immunotherapeutic approaches for treatment of chronic HBV infection. The review will focus on therapies targeting T cells and will cover checkpoint inhibitors, T cell engineering, Toll-like receptor agonists and therapeutic vaccination.

Treatments for HBV: A Glimpse into the Future

The hepatitis B virus is responsible for most of the chronic liver disease and liver cancer worldwide. As actual therapeutic strategies have had little success in eradicating the virus from hepatocytes, and as lifelong treatment is often required, new drugs targeting the various phases of the hepatitis B virus (HBV) lifecycle are currently under investigation. In this review, we provide an overview of potential future treatments for HBV.

Serum PreS1 and HBsAg ratio reflects liver fibrosis and predicts the development of hepatocellular carcinoma in chronic hepatitis B patients

While the preS1 region of the large hepatitis B surface protein plays an essential role in hepatitis B virus (HBV) infection, the effect of preS1 on liver fibrosis and hepatocarcinogenesis in chronic hepatitis B (CHB) patients is not well known. In this study, we measured serum preS1 levels by chemiluminescent immunoassay technology in 690 CHB patients and evaluated the correlation between serum preS1 levels and HBV, liver function markers and liver inflammation, fibrosis assessed by histological findings. Predictive factors for hepatocellular carcinoma (HCC) development in patients who had no previous history of HCC at the time of preS1 level measurement were also analysed. Median hepatitis B surface antigen (HBsAg) and preS1 levels were 3.08 log IU/mL and 98 ng/mL, respectively. PreS1 values were significantly correlated with serum HBsAg (p <0.001), hepatitis B core-related antigen (HBcrAg) (p <0.001) and HBV DNA levels (p <0.01). PreS1 values were also significantly correlated with serum alanine aminotransferase levels (p <0.001) and were significantly higher in patients who had higher grading of liver inflammatory activity (p <0.05). HBsAg level was correlated, but preS1/HBsAg ratio reflected liver fibrosis staging more directly than HBsAg alone. Multivariate analysis identified age ≥53 years (hazard ratio [HR], 18.360 for <53 years; p = 0.021) and preS1/HBsAg ratio ≥0.12 (HR, 6.205 for <0.12; p = 0.040) as significant and independent factors for HCC development in CHB patients. The preS1/HBsAg ratio directly reflects liver fibrosis, and the ratio might be a predictive marker for HCC development in CHB patients.

In-vitro and in-vivo models for hepatitis B cure research

PURPOSE OF REVIEW

Antiviral therapy for chronic hepatitis B infection is rarely curative, thus research in HBV cure strategies is a priority. Drug development and testing has been hampered by the lack of robust cell culture systems and small animal models. This review summarizes existing models for HBV cure research and focuses on recent developments since 2017 until today.

RECENT FINDINGS

The field has progressed in the development of cell culture and animal models to study HBV. Although early cell culture systems relied on transfection of HBV genomes in hepatoma cell lines, novel models expressing the entry receptor for HBV are susceptible to infection. Improved culture conditions for primary human hepatocytes, the primary target of HBV, have enabled the screening and validation of novel antivirals. Mouse models grafted with partially humanized livers are suitable for testing viral entry inhibitors or direct acting antivirals, and can be reconstituted with human immune cells to analyze immunotherapies. Other immunocompetent models include mice transduced with HBV genomes or woodchucks infected with their native hepatitis virus.

SUMMARY

Model systems for HBV research have helped lay the groundwork for the development and optimization of antiviral and immune-based therapeutic approaches that are now moving to clinical trials.

Blocking Entry of Hepatitis B and D Viruses to Hepatocytes as a Novel Immunotherapy for Treating Chronic Infections

Background

Chronic hepatitis B and D virus (HBV/HDV) infections can cause cancer. Current HBV therapy using nucleoside analogues (NAs) is life-long and reduces but does not eliminate the risk of cancer. A hallmark of chronic hepatitis B is a dysfunctional HBV-specific T-cell response. We therefore designed an immunotherapy driven by naive healthy T cells specific for the HDV antigen (HDAg) to bypass the need for HBV-specific T cells in order to prime PreS1-specific T cells and PreS1 antibodies blocking HBV entry.

Methods

Ten combinations of PreS1 and/or HDAg sequences were evaluated for induction of PreS1 antibodies and HBV- and HDV-specific T cells in vitro and in vivo. Neutralization of HBV by PreS1-specific murine and rabbit antibodies was evaluated in cell culture, and rabbit anti-PreS1 were tested for neutralization of HBV in mice repopulated with human hepatocytes.

Results

The best vaccine candidate induced T cells to PreS1 and HDAg, and PreS1 antibodies blocking HBV entry in vitro. Importantly, adoptive transfer of PreS1 antibodies prevented, or modulated, HBV infection after a subsequent challenge in humanized mice.

Conclusions

We here describe a novel immunotherapy for chronic HBV/HDV that targets viral entry to complement NAs and coming therapies inhibiting viral maturation.

Identification of novel hepatitis B virus therapeutic vaccine candidates derived from polymerase protein

Hepatitis B virus (HBV) infection is a worldwide health problem with high morbidity and mortality rates. The therapeutic vaccine is a promising method of treatment, and HBV polymerase plays a vital role in viral replication. Therefore, a therapeutic vaccine that binds to HBV DNA polymerase may control HBV infection. We predicted and selected epitopes of polymerase using online databases and analysis software. We then performed molecular docking and peptide binding assays to evaluate the binding energies and affinities between polymerase epitopes and the HLA-A0201 molecule. Finally, we induced T cells from the peripheral blood mononuclear cells (PBMCs) of healthy donors using each epitope and quantified the functions of epitope-specific T cells by IFN-γELISPOT assay, T2 cell cytotoxicity assay, HepG2.2.15 cell cytotoxicity assay and HBV gene expression assays. Four epitopes (RVTGGVFLV, GLLGFAAPF, LLDDEAGPL and YMDDVVLGA) had low binding energy and two epitopes (RVTGGVFLV and GLLGFAAPF) had a high binding affinity. The T cells stimulated by two epitopes (GLLGFAAPF and HLYSHPIIL) had a greater ability to induce immune response and suppress HBV. The HBV DNA polymerase epitopes identified in this study are promising targets for designing an epitope-based therapeutic vaccine against HBV.

The Multiple Functions of B Cells in Chronic HBV Infection

Chronic hepatitis B virus (HBV) infection is one of the main causes of liver diseases, of which the natural history and clinical outcomes are associated with the role of B cells. As humoral immune cells, B cells play a critical role in the process of anti-HBV antibody production. In addition, some studies have also characterized other B cell subsets involved in antigen presentation and regulating the immune response beyond antibody secretion. However, not all B cell subsets play a positive role in the immune response to chronic HBV infection, and various B cell subsets jointly mediate persistent HBV infection, tolerance, and liver damage. Thus, we further sought to elucidate the multiple functions of B cells to gain novel insight into the understanding of chronic hepatitis B (CHB) pathogenesis. We also reviewed the current immunotherapies targeting B cells to explore novel therapeutic interventions for the treatment of chronic HBV infection.

[Immunotherapies for the treatment of chronic hepatitis B virus infections-an overview with a focus on CAR T cells]

Derzeit leiden weltweit mehr als 250 Mio. Menschen an einer chronischen Infektion mit Hepatitis-B-Virus (CHB). Eine chronische Infektion geht mit einem erhöhten Risiko der Entwicklung einer Leberfibrose/-zirrhose und der Entwicklung eines hepatozellulären Karzinoms einher. Derzeit versterben jährlich ca. 0,8–1 Mio. Menschen an den Folgen einer chronischen Infektion. Eine Schwierigkeit bei der Therapie der CHB besteht darin, dass das virale Genom in Form eines Minichroms sehr lange Zeit persistieren kann bzw. dass virale Sequenzen in das Wirtsgenom inserieren können. Chronische Infektionen sind häufig durch funktionale Defekte der zellulären Immunantwort, insbesondere der T‑Zell-Antwort charakterisiert, was einer Eliminierung HBV-infizierter Zellen entgegensteht.

Immuntherapien zur Heilung der CHB zielen daher darauf ab, die antivirale Funktion der zellulären Immunantwort wiederherzustellen. Im Rahmen dieser Übersicht sollen verschiedene aktuelle Ansätze zur Immuntherapie der CHB beschrieben werden, insbesondere gentechnisch veränderte autologe T‑Zellen als mögliches Werkzeug zur Therapie der CHB. Weiterhin werden die Modulation von Checkpointinhibitoren der Immunantwort, metabolische T‑Zelltherapien und die therapeutische Impfung zur Stimulation der T‑Zellantwort als immuntherapeutische Strategien zur Therapie der chronischen HBV-Infektion zusammenfassend dargestellt.

HBV X protein-based therapeutic vaccine accelerates viral antigen clearance by mobilizing monocyte infiltration into the liver in HBV carrier mice

Background

Hepatitis B virus (HBV) persistently infected about 250 million people worldwide, and a curative treatment remains an unmet medical need. Among many approaches to treat chronic hepatitis B (CHB), therapeutic vaccines have been developed for two decades, but none have yielded promising results in clinical trials. Therefore, dissection of HBV clearance mechanisms during therapeutic vaccination in appropriate models, which could give rise to new curative therapies, is urgently needed. Growing evidence indicates that prolonged and intensive exposure of antigen-specific T cells to viral antigens is a major cause of T cell exhaustion, and decreases anti-HBV immunity efficacy of therapeutic vaccination. HBV X protein (HBx) is expressed at low levels, and the understanding of its immunogenicity and potential in therapeutic CHB vaccines is limited.

Methods

HBV genome sequences from CHB patients were cloned into a pAAV plasmid backbone and transfected into immunocompetent mouse hepatocytes through hydrodynamic injection. Mice carrying > 500 IU/mL serum HBV surface antigen (HBs) for more than 4 weeks were considered HBV carriers mimicking human CHB and received 3 doses of weekly HBx vaccine by subcutaneous immunization. Serum HBV clearance was evaluated by monitoring serum HBs and HBV-DNA titers. Residual HBV in the liver was evaluated by western blotting for HBV core antigen. The splenic antigen-specific T cell response was quantified by a 15-mer overlapping peptide-stimulated interferon-γ enzyme-linked immunospot assay. Blood and hepatic immune cells were quantified by flow cytometric analysis.

Results

Our HBx-based vaccine induced systemic HBx-specific CD4⁺ and CD8⁺ T cell responses in HBV carrier mice and demonstrated significant HBs and HBV-DNA elimination. The protective effect persisted for at least 30 days without additional booster immunization. Different infiltrating myeloid cell subsets, each with distinctive roles during immune-mediated HBV clearance, were found in the liver of vaccinated mice. During vaccine therapy, inflammatory monocyte depletion resulted in sustained HBV clearance inhibition, whereas phagocytic monocyte-derived macrophage and Kupffer cell elimination resulted in only transient inhibition of vaccine-induced HBV clearance.

Conclusions

We report the potential role of HBx as a major immunogen in an HBV therapeutic vaccine and the significance of a liver-infiltrating monocyte subset during hepatic viral clearance.

Dual-targeting nanoparticle vaccine elicits a therapeutic antibody response against chronic hepatitis B

Chronic hepatitis B is caused by prolonged infection with the hepatitis B virus (HBV), which can substantially increase the risk of developing liver disease. Despite the development of preventive vaccines against HBV, a therapeutic vaccine inducing an effective antibody response still remains elusive. The preS1 domain of the large HBV surface protein is the major viral attachment site on hepatocytes and thus offers a therapeutic target; however, its poor immunogenicity limits clinical translation. Here, we design a ferritin nanoparticle vaccine that can deliver preS1 to specific myeloid cells, including SIGNR1⁺ dendritic cells (which activate T follicular helper cells) and lymphatic sinus-associated SIGNR1⁺ macrophages (which can activate B cells). This nanoparticle vaccine induces a high-level and persistent anti-preS1 response that results in efficient viral clearance and partial serological conversion in a chronic HBV mouse model, offering a promising translatable vaccination strategy for the functional cure of chronic hepatitis B.

A potential ex vivo infection model of human induced pluripotent stem cell-3D organoids beyond coronavirus disease 2019

The novel coronavirus disease 2019 (COVID-19) outbreak began in the city of Wuhan, whereupon it rapidly spread throughout China and subsequently across the world. Rapid transmission of COVID-19 has caused wide-spread panic. Many established medications have been used to treat the disease symptoms; however, no specific drugs or vaccines have been developed. Organoids derived from human induced pluripotent stem cells (iPSCs) may serve as suitable infection models for ex vivo mimicking of the viral life cycle and drug screening. Human iPSC-3D organoids, self-organised tissues with multiple cell environments, have a similar structure and function as real human organs; hence, these organoids allow greater viral infection efficiency, mimic the natural host-virus interactions, and are suitable for long-term experimentation. Here, we suggest the use of a functional human iPSC-organoid that could act as a reliable and feasible ex vivo infection model for investigation of the virus. This approach will provide much needed insight into the underlying molecular dynamics of COVID-19 for the development of novel treatment and prevention strategies.

Advances in Targeting the Innate and Adaptive Immune Systems to Cure Chronic Hepatitis B Virus Infection

“Functional cure” is being pursued as the ultimate endpoint of antiviral treatment in chronic hepatitis B (CHB), which is characterized by loss of HBsAg whether or not anti-HBs antibodies are present. “Functional cure” can be achieved in <10% of CHB patients with currently available therapeutic agents. The dysfunction of specific immune responses to hepatitis B virus (HBV) is considered the major cause of persistent HBV infection. Thus, modulating the host immune system to strengthen specific cellular immune reactions might help eliminate HBV. Strategies are needed to restore/enhance innate immunity and induce HBV-specific adaptive immune responses in a coordinated way. Immune and resident cells express pattern recognition receptors like TLRs and RIG I/MDA5, which play important roles in the induction of innate immunity through sensing of pathogen-associated molecular patterns (PAMPs) and bridging to adaptive immunity for pathogen-specific immune control. TLR/RIG I agonists activate innate immune responses and suppress HBV replication in vitro and in vivo, and are being investigated in clinical trials. On the other hand, HBV-specific immune responses could be induced by therapeutic vaccines, including protein (HBsAg/preS and HBcAg), DNA, and viral vector-based vaccines. More than 50 clinical trials have been performed to assess therapeutic vaccines in CHB treatment, some of which display potential effects. Most recently, using genetic editing technology to generate CAR-T or TCR-T, HBV-specific T cells have been produced to efficiently clear HBV. This review summarizes the progress in basic and clinical research investigating immunomodulatory strategies for curing chronic HBV infection, and critically discusses the rather disappointing results of current clinical trials and future strategies.

Hepatitis B vaccination and immunotherapies: an update

World Health Organization (WHO) estimates that 257 million people were living with chronic hepatitis B virus (HBV) infection. Highest HBV prevalence was found in the WHO Western Pacific Region (6.2%) and in the WHO African Region (6.1%). The HBV vaccine is the best protection against chronic HBV infection and its complications. Globally, routine infant immunization against HBV has increased with an estimated coverage of 84% in 2017. Nevertheless, in many countries further efforts are needed to implement this coverage and ensure national immunization programs for people at major risk for HBV infection. Therapeutic vaccination in chronic HBV infected patients can cause anti-HBV immune responses able to remove and/or cure infected hepatocytes. It shows promising results in murine model and human trials, but these results need to be consolidated by further multicenter clinical studies. In particular, the efficacy of therapeutic vaccine seems to improve by combination therapies.

PreS1 Mutations Alter the Large HBsAg Antigenicity of a Hepatitis B Virus Strain Isolated in Bangladesh

Mutations in the hepatitis B virus (HBV) genome can potentially lead to vaccination failure, diagnostic escape, and disease progression. However, there are no reports on viral gene expression and large hepatitis B surface antigen (HBsAg) antigenicity alterations due to mutations in HBV isolated from a Bangladeshi population. Here, we sequenced the full genome of the HBV isolated from a clinically infected patient in Bangladesh. The open reading frames (ORFs) (P, S, C, and X) of the isolated HBV strain were successfully amplified and cloned into a mammalian expression vector. The HBV isolate was identified as genotype C (sub-genotype C2), serotype adr, and evolutionarily related to strains isolated in Indonesia, Malaysia, and China. Clinically significant mutations, such as preS1 C2964A, reverse transcriptase domain I91L, and small HBsAg N3S, were identified. The viral P, S, C, and X genes were expressed in HEK-293T and HepG2 cells by transient transfection with a native subcellular distribution pattern analyzed by immunofluorescence assay. Western blotting of large HBsAg using preS1 antibody showed no staining, and preS1 ELISA showed a significant reduction in reactivity due to amino acid mutations. This mutated preS1 sequence has been identified in several Asian countries. To our knowledge, this is the first report investigating changes in large HBsAg antigenicity due to preS1 mutations.

Designing a therapeutic hepatitis B vaccine to circumvent immune tolerance

An effective prophylactic hepatitis B virus (HBV) vaccine has long been available but is ineffective for chronic infection. The primary cause of chronic hepatitis B (CHB) and greatest impediment for a therapeutic vaccine is the direct and indirect effects of immune tolerance to HBV antigens. The resulting defective CD4⁺/CD8⁺ T cell response, poor cytokine production, insufficient neutralizing antibody (nAb) and poor response to HBsAg vaccination characterize CHB infection. The objective of this study was to develop virus-like-particles (VLPs) that elicit nAb to prevent viral spread and prime CD4⁺/CD8⁺ T cells to eradicate intracellular HBV. Eight neutralizing B cell epitopes from the envelope PreS1 region were consolidated onto a species-variant of the HBV core protein, the woodchuck hepatitis core antigen (WHcAg). PreS1-specific B cell epitopes were chosen because of preferential expression on HBV virions. Because WHcAg and HBcAg are not crossreactive at the B cell level and only partially cross-reactive at the CD4⁺/CD8⁺ T cell level, CD4⁺ T cells specific for WHcAg-unique T cell sites can provide cognate T-B cell help for anti-PreS1 Ab production that is not curtailed by immune tolerance. Immunization of immune tolerant HBV transgenic (Tg) mice with PreS1-WHc VLPs elicited levels of high titer anti-PreS1 nAbs equivalent to wildtype mice. Passive transfer of PreS1 nAbs into human-liver chimeric mice prevented acute infection and cleared serum HBV from mice previously infected with HBV in a model of CHB. At the T cell level, PreS1-WHc VLPs and hybrid WHcAg/HBcAg DNA immunogens elicited HBcAg-specific CD4⁺ Th and CD8⁺ CTL responses.

Poly I:C-based rHBVvac therapeutic vaccine eliminates HBV via generation of HBV-specific CD8+ effector memory T cells

OBJECTIVE

Chronic hepatitis B (CHB) virus infection is a global health problem. Finding a cure for CHB remains a challenging task.

DESIGN

In this study, poly I:C was employed as an adjuvant for HBV therapeutic vaccine (referred to as pHBV-vaccine) and the feasibility and efficiency of pHBV-vaccine in CHB treatment were evaluated in HBV-carrier mice.

RESULTS

We found that pHBV-vaccine decreased HBsAg and HBV DNA efficiently and safely in HBV-carrier mice. Further investigation showed that pHBV-vaccine promoted maturation and antigen presentation ability of dendritic cells in vivo and in vitro. This vaccine successfully restored the exhaustion of antigen-specific CD8⁺ T cells and partly broke the immune tolerance established in HBV-carrier mice. pHBV-vaccine also enhanced the proliferation and polyfunctionality of HBV-specific CD11a^hi CD8α^lo cells. Importantly, we observed that T cell activation molecule KLRG1 was only expressed on HBV specific CD11a^hi CD8α^lo cells. Furthermore, pHBV-vaccine reduced the expression of Eomes and increased the serum IL-12 levels, which in turn promoted the generation of effector memory short-lived effector cells (SLECs) to exhibit a critical role in HBV clearance. SLECs induced by pHBV-vaccine might play a crucial role in protecting from HBV reinfection.

CONCLUSIONS

Findings from this study provide a new basis for the development of therapeutic pHBV-vaccine, which might be a potential candidate for clinical CHB therapy.

Interferon alpha treatment leads to a high rate of hepatitis B surface antigen seroconversion in Chinese children with chronic hepatitis B

Chronic hepatitis B virus (HBV) infection (CHB) in children remains a public health challenge despite significant success in programme is established to prevent mother-to-child transmission. In particular, CHB in Chinese children are mostly acquired through vertical transmission, which differs from the common infection route reported in other countries and regions. This situation has resulted in a high endemic prevalence of CHB in Chinese adults. Thus, successful treatment of children with CHB will prevent the development of advanced liver diseases in late adulthood. However, there is still no consensus on the clinical guideline to treat paediatric CHB. In this study, we evaluated the potential of interferon alpha (IFNa) treatment for Chinese children with CHB. A total of 41 patients with CHB aged 3-17 years were enrolled in this retrospective study: 21 patients were treated with pegylated (PEG)-IFNa and 20 patients without treatment served as the control group. The rates of HBV DNA suppression, hepatitis B e antigen (HBeAg) clearance and hepatitis B surface antigen (HBsAg) clearance were significantly higher in the PEG-IFNa treatment group than in the control group (P < 0.05 at 48 weeks). Unexpectedly, PEG-IFNa treatment achieved a high rate of HBsAb production, far exceeding the clinical outcome in documented PEG-IFNa-treated CHB adults. Further analysis revealed that younger children (3-6 years old) were more responsive to PEG-IFNa treatment with respect to achieving a protective level of HBsAb in a short treatment cycle than adolescents (10-17 years old). Overall, these results indicate that the immune system of children might have a preserved PEG-IFNa-mediated mechanism to completely control HBV, which can help to design new strategies to treat CHB patients.

Heterologous prime-boost immunization with vesiculovirus-based vectors expressing HBV Core antigen induces CD8+ T cell responses in naïve and persistently infected mice and protects from challenge

Chronic hepatitis B virus (HBV) infections cause more than 800,000 deaths per year and currently approved treatments do not cure the disease. Because a hallmark of acute infection resolution is the presence of functional CD8⁺ T cells to the virus, activation of the immune system with therapeutic vaccines represents a potential approach for treating chronic hepatitis B. In this study, we evaluated the immunogenicity and efficacy of two attenuated vesiculovirus-based platforms expressing HBV Core antigen, the highly attenuated vesicular stomatitis virus (VSV) N4CT1 and a unique vaccine platform [virus-like vesicles (VLV)] that is based on a Semliki Forest virus replicon expressing the VSV glycoprotein. We found that heterologous prime-boost immunization with VLV and N4CT1 induced Core-specific CD8⁺ T cell responses in naïve mice. When immunized mice were later challenged with AAV-HBV, functional Core-specific CD8⁺ T cells were present in the liver, and mice were protected from establishment of persistent infection. In contrast, when mice with pre-established persistent HBV replication received prime-boost immunization, functional Core-specific CD8⁺ T cells were found in the spleen but not in the liver. These results highlight the importance of investigating the therapeutic value of different HBV antigens alone and in combination using preclinical animal models, and understanding the correlation between anti-HBV efficacy in these models with human infection.

Current and emerging therapies to combat persistent intracellular pathogens

Intracellular pathogens such as HIV, hepatitis B virus, and Mycobacterium tuberculosis are responsible for millions of deaths worldwide and represent major obstacles to global health. Current treatment options have improved patient outcomes and extended life-expectancy in many countries; however, challenges such as latency, drug-resistance, and inflammatory pathology have necessitated advancements in curative strategies which go beyond the traditional antimicrobial focus. This review highlights recent advances in host-directed therapies to eradicate intracellular pathogens or augment the endogenous immune response by targeting host cell pathways. The 'kick and kill' strategy for HIV latency, adjunct immunomodulatory compounds for tuberculosis, and pro-apoptotic small-molecule inhibitors in the case of chronic Hepatitis B are promising examples of host-directed therapies that signal a paradigm shift in treatment and management of chronic infectious disease.

HoxA10 Facilitates SHP-1-Catalyzed Dephosphorylation of p38 MAPK/STAT3 To Repress Hepatitis B Virus Replication by a Feedback Regulatory Mechanism

Hepatitis B virus (HBV) infection is the leading cause of chronic hepatitis B (CHB), liver cirrhosis (LC), and hepatocellular carcinoma (HCC). This study reveals a distinct mechanism underlying the regulation of HBV replication. HBV activates homeobox A10 (HoxA10) in human hepatocytes, leukocytes, peripheral blood mononuclear cells (PBMCs), HepG2-NTCP cells, leukocytes isolated from CHB patients, and HBV-associated HCC tissues. HoxA10 in turn represses HBV replication in human hepatocytes, HepG2-NTCP cells, and BALB/c mice. Interestingly, we show that during early HBV infection, p38 mitogen-activated protein kinase (MAPK) and signal transducer and activator of transcription 3 (STAT3) were activated to facilitate HBV replication; however, during late HBV infection, HoxA10 was induced to attenuate HBV replication. Detailed studies reveal that HoxA10 binds to p38 MAPK, recruits SH2-containing protein tyrosine phosphatase 1 (SHP-1) to facilitate SHP-1 in catalyzing dephosphorylation of p38 MAPK/STAT3, and thereby attenuates p38 MAPK/STAT3 activation and HBV replication. Furthermore, HoxA10 binds to the HBV enhancer element I (EnhI)/X promoter, competes with STAT3 for binding of the promoter, and thereby represses HBV transcription. Taken together, these results show that HoxA10 attenuates HBV replication through repressing the p38 MAPK/STAT3 pathway by two approaches: HoxA10 interacts with p38 MAPK and recruits SHP-1 to repress HBV replication, and HoxA10 binds to the EnhI/X promoter and competes with STAT3 to attenuate HBV transcription. Thus, the function of HoxA10 is similar to the action of interferon (IFN) in terms of inhibition of HBV infection; however, the mechanism of HoxA10-mediated repression of HBV replication is different from the mechanism underlying IFN-induced inhibition of HBV infection.IMPORTANCE Two billion people have been infected with HBV worldwide; about 240 million infected patients developed chronic hepatitis B (CHB), and 650,000 die each year from liver cirrhosis (LC) or hepatocellular carcinoma (HCC). This work elucidates a mechanism underlying the control of HBV replication. HBV infection activates HoxA10, a regulator of cell differentiation and cancer progression, in human cells and patients with CHB and HCC. HoxA10 subsequently inhibits HBV replication in human tissue culture cells and mice. Additionally, HoxA10 interacts with p38 MAPK to repress the activation of p38 MAPK and STAT3 and recruits and facilitates SHP-1 to catalyze the dephosphorylation of p38 MAPK and STAT3. Moreover, HoxA10 competes with STAT3 for binding of the HBV X promoter to repress HBV transcription. Thus, this work reveals a negative regulatory mechanism underlying the control of HBV replication and provides new insights into the development of potential agents to control HBV infection.

A Highly Attenuated Vesicular Stomatitis Virus-Based Vaccine Platform Controls Hepatitis B Virus Replication in Mouse Models of Hepatitis B

Therapeutic vaccines may be an important component of a treatment regimen for curing chronic hepatitis B virus (HBV) infection. We previously demonstrated that recombinant wild-type vesicular stomatitis virus (VSV) expressing the HBV middle surface glycoprotein (MHBs) elicits functional immune responses in mouse models of HBV replication. However, VSV has some undesirable pathogenic properties, and the use of this platform in humans requires further viral attenuation. We therefore generated a highly attenuated VSV that expresses MHBs and contains two attenuating mutations. This vector was evaluated for immunogenicity, pathogenesis, and anti-HBV function in mice. Compared to wild-type VSV, the highly attenuated virus displayed markedly reduced pathogenesis but induced similar MHBs-specific CD8⁺ T cell and antibody responses. The CD8⁺ T cell responses elicited by this vector in naive mice prevented HBV replication in animals that were later challenged by hydrodynamic injection or transduction with adeno-associated virus encoding the HBV genome (AAV-HBV). In mice in which persistent HBV replication was first established by AAV-HBV transduction, subsequent immunization with the attenuated VSV induced MHBs-specific CD8⁺ T cell responses that corresponded with reductions in serum and liver HBV antigens and nucleic acids. HBV control was associated with an increase in the frequency of intrahepatic HBV-specific CD8⁺ T cells and a transient elevation in serum alanine aminotransferase activity. The ability of VSV to induce a robust multispecific T cell response that controls HBV replication combined with the improved safety profile of the highly attenuated vector suggests that this platform offers a new approach for HBV therapeutic vaccination.IMPORTANCE A curative treatment for chronic hepatitis B must eliminate the virus from the liver, but current antiviral therapies typically fail to do so. Immune-mediated resolution of infection occurs in a small fraction of chronic HBV patients, which suggests the potential efficacy of therapeutic strategies that boost the patient's own immune response to the virus. We modified a safe form of VSV to express an immunogenic HBV protein and evaluated the efficacy of this vector in the prevention and treatment of HBV infection in mouse models. Our results show that this vector elicits HBV-specific immune responses that prevent the establishment of HBV infection and reduce viral proteins in the serum and viral DNA/RNA in the liver of mice with persistent HBV replication. These findings suggest that highly attenuated and safe virus-based vaccine platforms have the potential to be utilized for the development of an effective therapeutic vaccine against chronic HBV infection.

Screening of microRNAs for a repressor of hepatitis B virus replication

Background

Hepatitis B virus (HBV) infection is a leading cause of persistent liver diseases, cirrhosis and hepatocellular carcinoma (HCC) worldwide. Since deregulation of microRNA (miRNA) expression by HBV infection contributes to enhanced viral replication and pathogenesis, modulation of miRNA activity can be a novel therapeutic approach towards HBV eradication. As the effects of the vast majority of miRNAs on HBV replication have not been empirically investigated, here, we aim to identify novel therapeutic targets that have a strong antiviral effect on HBV.

Methods

HepG2-hNTCP-C4 cells were infected with HBV, and then were individually transfected with the library mimics of 2048 miRNAs. To assess the amount of intracellular and extracellular DNA and HBsAg, qPCR and ELISA were performed respectively.

Results

From miRNA library screening, we identified 39 miRNAs as candidate repressors of HBV replication. Among them, 9 miRNAs, including miR-204, strongly decreased both HBV DNA and HBsAg in culture supernatant of HepG2-hNTCP-C4 cells. Furthermore, we also showed that inhibition of Rab22a, one of the targets of miR-204, also suppressed intracellular and extracellular HBV DNA expression in HepG2.2.15.7 cells.

Conclusions

Our findings contribute to the understanding of the roles of miRNAs underlying HBV replication and show the possibility of developing a novel strategy for miRNA-mediated HBV treatment.

The immune response of rhesus macaques to novel vaccines comprising hepatitis B virus S, PreS1, and Core antigens

Therapeutic vaccines represent a unique approach to hepatitis B virus (HBV) treatment and have the potential to induce long-term control of infection. This study explored the immune responses of rhesus macaques to novel vaccines comprising the S, PreS1, and Core antigens of the HBV that showed promise as prophylactic and therapeutic approaches in a mouse model. The tested vaccines included two DNA vaccines (pVRC-SS1, pVRC-CS1), an HBV particle subunit (HBSS1) vaccine and the recombinant vaccinia virus- (RVJ-) based vaccines (RVJSS1 and RVJCS1) in which SS1 containing S (1-223 aa) and PreS1 (21-47 aa), CS1 containing Core (1-144 aa) and PreS1 (1-42 aa). The humoral immunity and cell-mediated immunity (CMI) induced by vaccines comprising the S, PreS1, and Core antigens of HBV were investigated in a longitudinal study that continued up to 98 weeks after the firstvaccination. In rhesus macaques, anti-PreS1 antibody was induced more rapidly than anti-S or anti-Core antibody after DNA vaccination. The antibody and cell-mediated immune responses against S, PreS1, and C were significantly enhanced in macaques boosted with RVJSS1 and RVJCS1, whereas the cell-mediated response to C was most robust and durable. The immune response to S, PreS1, and C was restored by HBSS1 boosting and detected in macaques until weeks 74 and 98 after the first vaccination. Additionally, robust neutralizing activity was detected at week 52. In conclusion, novel HBV vaccine candidates, especially those used for therapeutic applications should incorporate the PreS1 and Core antigens.

Analysis of epitope-based vaccine candidates against the E antigen of the hepatitis B virus based on the B genotype sequence: An in silico and in vitro approach

Chronic hepatitis B virus infection is a worldwide health problem with no current effective strategy to achieve a cure. The Hepatitis B virus (HBV) E antigen (HBeAg) has a negative effect on the immune system and a therapeutic vaccine is a promising strategy in order to treat chronic virus infection. In this study, we analyzed and identified the MHC-I, MHC-II and B cell epitopes of the HBeAg based on a B genotype sequence of HBV using a bioinformatic approach and in vitro experiments. The computational approach provided us with four epitopes (LLWFHISCL, YLVSFGVWI, MQLFHLCLI, TVLEYLVSF) of the specific MHC-I allele HLA-A0201 that conformed to all criteria. Molecular docking and a peptide binding assay showed that epitope TVLEYLVSF had the lowest binding energy and epitope LLWFHISCL had the highest binding affinity to the HLA-A0201 molecule. An interferonγenzyme-linked immunospot assay and cytotoxicity assay revealed that epitope LLWFHISCL had the highest ability to induce and stimulate T cells. Furthermore, we determined four core peptides of MHC-II epitopes and a region of the B cell epitope. The epitopes and region identified in this research may be helpful in designing epitope-based vaccines and boosting the mechanism research of HBeAg and its effect on the immune system.

MYD88 L265P Mutation in Lymphoid Malignancies

Next-generation sequencing has revealed cancer genomic landscapes, in which over 100 driver genes that, when altered by intragenic mutations, can promote oncogenesis. MYD88 is a driver gene found in hematologic B-cell malignancies. A missense mutation (L265P) changing leucine at position 265 to proline in MYD88 is found in ∼90% of Waldenström macroglobulinemia (WM) cases and in significant portions of activated B-cell diffuse large B-cell lymphomas and IgM monoclonal gammopathy of undetermined significance. Few cancers such as WM have a single amino acid substitution in one gene like MYD88 L265P that occurs in ∼90% of cases, making WM paradigmatic for study of a single causative mutation in oncogenesis. In this review, we summarize the frequency and cancer spectrum of MYD88 L265P and its downstream effects in lymphoid cancers. Malignant B cells with MYD88 L265P are likely transformed from IgM-producing B cells either in response to T-cell-independent antigens or in response to protein antigens before class switching. We also discuss therapeutic strategies that include targeting Bruton tyrosine kinase and other kinases, interfering with the assembly of MYD88 and its interacting partners, and MYD88 L265P-specific peptide-based immunotherapy. Cancer Res; 78(10); 2457-62. ©2018 AACR.

Current advances in the elimination of hepatitis B in China by 2030

With its 78 million chronic carriers, hepatitis B virus (HBV) infection is still one of the leading public health challenges in China. Over the last two decades, China has made great progress on the prevention of HBV transmission through national vaccination programs. Zero transmission from mother to infant has been proposed as the current goal. Available anti-HBV therapy is efficacious in suppressing HBV replication; however, it fails to completely cure patients with chronic hepatitis B and even requires lifelong treatment. To reduce the costs and improve the efficacy, several trials have been recently conducted in China to optimize the current anti-HBV managements. Novel biomarkers were identified to predict treatment outcomes, and new promising treatment strategies were developed. Reports also indicate that coinfections of HBV with other hepatotropic viruses and human immunodeficiency virus are common in China and cause severe liver diseases, which should be recognized early and treated properly. Work is still needed to eliminate hepatitis B in China by 2030.

New Viral and Immunological Targets for Hepatitis B Treatment and Cure: A Review

Although current therapies can be successful at suppressing hepatitis B viral load, long-term viral cure is not within reach. Subsequent strategies combining pegylated interferon alfa with nucleoside/nucleotide analogues have not resulted in any major paradigm shift. An improved understanding of the hepatitis B virus (HBV) lifec ycle and virus-induced immune dysregulation has, however, revealed many potential therapeutic targets, and there are hopes that treatment of hepatitis B could soon be revolutionized. This review summarizes the current developments in HBV therapeutics-both virus directed and host directed.

Enrichment of Ly6Chi monocytes by multiple GM-CSF injections with HBV vaccine contributes to viral clearance in a HBV mouse model

Adjuvants are considered a necessary component for HBV therapeutic vaccines but few are licensed in clinical practice due to concerns about safety or efficiency. In our recent study, we established that a combination protocol of 3-day pretreatments with GM-CSF before a vaccination (3 × GM-CSF+VACCINE) into the same injection site could break immune tolerance and cause over 90% reduction of HBsAg level in the HBsAg transgenic mouse model. Herein, we further investigated the therapeutic potential of the combination in AAV8–1.3HBV-infected mice. After 4 vaccinations, both serum HBeAg and HBsAg were cleared and there was a 95% reduction of HBV-positive hepatocytes, in addition to the presence of large number of infiltrating CD8⁺ T cells in the livers. Mechanistically, the HBV-specific T-cell responses were elicited via a 3 × GM-CSF+VACCINE-induced conversion of CCR2-dependent CD11b⁺ Ly6C^hi monocytes into CD11b⁺CD11c⁺ DCs. Experimental depletion of Ly6C^hi monocytes resulted in a defective HBV-specific immune response thereby abrogating HBV eradication. This vaccination strategy could lead to development of an effective therapeutic protocol against chronic HBV in infected patients.

Detection of the hepatitis B virus (HBV) covalently-closed-circular DNA (cccDNA) in mice transduced with a recombinant AAV-HBV vector

Hepatitis B Virus (HBV) persists in infected hepatocytes as an episomal covalently-closed-circular DNA mini-chromosome, called cccDNA. As the main nuclear transcription template, HBV cccDNA is a key replication intermediate in the viral life cycle. Little is known about the mechanisms involved in its formation, maintenance and fate under antiviral therapies. This is mainly due to the lack of small immune-competent animal models able to recapitulate the entire HBV replication cycle, including formation of HBV cccDNA. Here we report that HBV cccDNA can be detected by Southern blot analyses in the liver of C57BL6 mice transduced with AAV-HBV. HBV cccDNA persists in the liver of these animals together with the AAV-HBV episome. We also set up a PCR strategy to distinguish the HBV cccDNA from the AAV-HBV episome. These suggest that the AAV-HBV/mouse model might be relevant to test drugs targeting HBV cccDNA regulation and persistence.