A global scientific strategy to cure hepatitis B

Single-cell RNA sequencing of liver fine-needle aspirates captures immune diversity in the blood and liver in chronic hepatitis B patients

BACKGROUND AND AIMS

HBV infection is restricted to the liver, where it drives exhaustion of virus-specific T and B cells and pathogenesis through dysregulation of intrahepatic immunity. Our understanding of liver-specific events related to viral control and liver damage has relied almost solely on animal models, and we lack useable peripheral biomarkers to quantify intrahepatic immune activation beyond cytokine measurement. Our objective was to overcome the practical obstacles of liver sampling using fine-needle aspiration and develop an optimized workflow to comprehensively compare the blood and liver compartments within patients with chronic hepatitis B using single-cell RNA sequencing.

APPROACH AND RESULTS

We developed a workflow that enabled multi-site international studies and centralized single-cell RNA sequencing. Blood and liver fine-needle aspirations were collected, and cellular and molecular captures were compared between the Seq-Well S 3 picowell-based and the 10× Chromium reverse-emulsion droplet-based single-cell RNA sequencing technologies. Both technologies captured the cellular diversity of the liver, but Seq-Well S 3 effectively captured neutrophils, which were absent in the 10× dataset. CD8 T cells and neutrophils displayed distinct transcriptional profiles between blood and liver. In addition, liver fine-needle aspirations captured a heterogeneous liver macrophage population. Comparison between untreated patients with chronic hepatitis B and patients treated with nucleoside analogs showed that myeloid cells were highly sensitive to environmental changes while lymphocytes displayed minimal differences.

CONCLUSIONS

The ability to electively sample and intensively profile the immune landscape of the liver, and generate high-resolution data, will enable multi-site clinical studies to identify biomarkers for intrahepatic immune activity in HBV and beyond.

Development of monoclonal antibodies to target the large surface protein of hepatitis B virus and their use in therapeutic and diagnostic applications

Over 250 million people are living with chronic infection caused by the hepatitis B virus (HBV). HBV has three surface proteins, namely small (SHBs), medium (MHBs) and large (LHBs), and they play different roles in the virus life cycle. The approved hepatitis B vaccine only contains the SHBs protein and many studies have focused on characterising the functional domains in SHBs. Although the LHBs protein is less studied, recent studies have shown that it plays important roles in mediating viral entry, replication and assembly. Over the years, there have been major advancements in monoclonal antibody (mAb) discovery tools and multiple mAbs have been developed to specifically target the preS1 domain in LHBs. We summarise the HBV infection systems and antibody discovery strategies that have been utilised by various research groups to assess the potential use of anti-preS1 mAbs as therapeutic antibodies against HBV or in the development of new diagnostic assays.

Conditional replication and secretion of hepatitis B virus genome uncover the truncated 3' terminus of encapsidated viral pregenomic RNA

IMPORTANCE

The biogenesis and clinical application of serum HBV pgRNA have been a research hotspot in recent years. This study further characterized the heterogeneity of the 3' terminus of capsid RNA by utilizing a variety of experimental systems conditionally supporting HBV genome replication and secretion, and reveal that the 3' truncation of capsid pgRNA is catalyzed by cellular ribonuclease(s) and viral RNaseH at positions after and before 3' DR1, respectively, indicating the 3' DR1 as a boundary between the encapsidated portion of pgRNA for reverse transcription and the 3' unprotected terminus, which is independent of pgRNA length and the 3' terminal sequence. Thus, our study provides new insights into the mechanism of pgRNA encapsidation and reverse transcription, as well as the optimization of serum HBV RNA diagnostics.

A CRISPR-based system to investigate HBV cccDNA biology

IMPORTANCE

Hepatitis B virus cccDNA is the key target for the necessary development of antiviral therapies aimed at curing chronic hepatitis B. The CRISPR-based system to produce covalently closed circular (cccDNA)-like extrachromosomal DNAs described in this report enables large-scale screens of chemical libraries to identify drug candidates with the potential to permanently inactivate cccDNA. Moreover, this approach permits investigations on unresolved problems as described in this report concerning cccDNA biology including mechanisms of SMC5/6-dependent transcriptional silencing and the contributions of the SMC5/6 complex to cccDNA stability in resting and dividing hepatocytes.

Special Issue "Hepatitis B Virus: New Breakthroughs to Conquer an Ancient Disease"

Chronic hepatitis B affects >300 million people worldwide and is a major cause of liver disease, causing ~800,000 deaths each year [...].

Hepatitis B Virus Genotype H: Epidemiological, Molecular, and Clinical Characteristics in Mexico

The hepatitis B virus (HBV), comprising of ten genotypes (A-J), has been a silent threat against humanity, constituting a public health problem worldwide. In 2016, the World Health Organization set forth an impressive initiative for the global elimination of viral hepatitis by 2030. As the target date approaches, many nations, particularly in the Latin American region, face challenges in designing and implementing their respective elimination plan. This review aimed to portray the state of knowledge about the epidemiological, molecular, and clinical characteristics of HBV genotype H (HBV/H), endemic to Mexico. PubMed, Scopus, Web of Science, and Google Scholar were searched to compile scientific literature over 50 years (1970-2022). A total of 91 articles were organized into thematic categories, addressing essential aspects such as epidemiological data, risk factors, HBV genotype distribution, HBV mixed infections, clinical characteristics, and vaccination. The prevalence and its associated 95% confidence interval (95% CI) were estimated using the Metafor package in R programming language (version 4.1.2). We provide insights into the strengths and weaknesses in diagnostics and prevention measures that explain the current epidemiological profile of HBV/H. Training, research, and awareness actions are required to control HBV infections in Mexico. These actions should contribute to creating more specific clinical practice guides according to the region's characteristics. Mexico's elimination plan for HBV will require teamwork among the government health administration, researchers, physicians, specialists, and civil society advocates to overcome this task jointly.

Clinical cure of hepatitis B: Delight and anticipation

Chronic hepatitis B (CHB) patients achieving clinical cure represent individuals who have attained persistent virological suppression and immunological control. This is the ideal treatment goal in both domestic and international CHB management guidelines. Clinical practice has demonstrated promising outcomes for certain patient populations treated with optimized regimens involving nucleos(t)ide analogs (NAs) or immunomodulators (such as pegylated interferon α) administered sequentially or in combination. However, despite the gratifying progress in the clinical management of hepatitis B, a significant number of patients still cannot achieve the goal of clinical cure. Many challenges remain to be overcome to achieve better treatment outcomes. This article provides a brief overview of the current research progress and existing issues in the pursuit of clinical cure of hepatitis B.

Oncostatin M Induces IFITM1 Expression to Inhibit Hepatitis B Virus Replication Via JAK-STAT Signaling

BACKGROUND & AIMS

Functional cure is achieved by a limited number of patients with chronic hepatitis B (CHB) after nucleotide analogue(s) and interferon treatment. It is urgent to develop therapies that can help a larger proportion of patients achieve functional cure. The present study was designed to explore the anti-hepatitis B virus (HBV) potency of interleukin-6 family cytokines and to characterize the underlying mechanisms of the cytokine displaying the highest anti-HBV potency.

METHODS

HBV-infected cells were used to screened the anti-HBV potency of interleukin-6 family cytokines. The concentration of oncostatin M (OSM) in patients with chronic HBV infection was examined by enzyme-linked immunosorbent assay. The underlying mechanism of OSM anti-HBV was explored through RNA-seq. C57BL/6 mice injected with rAAV8-1.3HBV were used to explore the suppression effect of OSM on HBV in vivo.

RESULTS

OSM is the most effective of the interleukin-6 family cytokines for suppression of HBV replication (percentage of average inhibition: hepatitis B surface antigen, 34.44%; hepatitis B e antigen, 32.52%; HBV DNA, 61.57%). Hepatitis B e antigen-positive CHB patients with high OSM levels had lower hepatitis B surface antigen and hepatitis B e antigen than those with low levels. OSM activated JAK-STAT signaling pathway promoting the formation of STAT1-IRF9 transcription factor complex. Following this, OSM increased the expression of various genes with known functions in innate and adaptive immunity, which was higher expression in patients with CHB in immune clearance phase than in immune tolerance phase (data from GEO: GSE65359). Interferon-induced transmembrane protein 1, one of the most differentially expressed genes, was identified as an HBV restriction factor involved in OSM-mediated anti-HBV effect. In vivo, we also found OSM significantly inhibited HBV replication and induced expression of antiviral effector interferon-induced transmembrane protein 1.

CONCLUSIONS

Our study shows that OSM remodels the immune response against HBV and exerts potent anti-HBV activity, supporting its further development as a potential therapy for treating CHB.

Hepatitis B surface antigen reduction is associated with hepatitis B core-specific CD8+ T cell quality

Despite treatment, hepatitis B surface antigen (HBsAg) persists in patients with chronic hepatitis B (CHB), suggesting the likely presence of the virus in the body. CD8+ T cell responses are essential for managing viral replication, but their effect on HBsAg levels remains unclear. We studied the traits of activated CD8+ T cells and HBV-specific CD8+ T cells in the blood of CHB patients undergoing nucleos(t)ide analog (NUC) therapy. For the transcriptome profiling of activated CD8+ T cells in peripheral blood mononuclear cells (PBMCs), CD69+ CD8+ T cells were sorted from six donors, and single-cell RNA sequencing (scRNA-seq) analysis was performed. To detect HBV-specific CD8+ T cells, we stimulated PBMCs from 26 donors with overlapping peptides covering the HBs, HBcore, and HBpol regions of genotype A/B/C viruses, cultured for 10 days, and analyzed via multicolor flow cytometry. scRNA-seq data revealed that CD8+ T cell clusters harboring the transcripts involved in the cytolytic functions were frequently observed in donors with high HBsAg levels. Polyfunctional analysis of HBV-specific CD8+ T cells utilized by IFN-γ/TNFα/CD107A/CD137 revealed that HBcore-specific cells exhibited greater polyfunctionality, suggesting that the quality of HBV-specific CD8+ T cells varies among antigens. Moreover, a subset of HBcore-specific CD8+ T cells with lower cytolytic potential was inversely correlated with HBsAg level. Our results revealed a stimulant-dependent qualitative difference in HBV-specific CD8+ T cells in patients with CHB undergoing NUC therapy. Hence, the induction of HBcore-specific CD8+ T cells with lower cytolytic potential could be a new target for reducing HBsAg levels.

Mechanisms and research advances in mRNA antibody drug-mediated passive immunotherapy

Antibody technology is widely used in the fields of biomedical and clinical therapies. Nonetheless, the complex in vitro expression of recombinant proteins, long production cycles, and harsh storage conditions have limited their applications in medicine, especially in clinical therapies. Recently, this dilemma has been overcome to a certain extent by the development of mRNA delivery systems, in which antibody-encoding mRNAs are enclosed in nanomaterials and delivered to the body. On entering the cytoplasm, the mRNAs immediately bind to ribosomes and undergo translation and post-translational modifications. This process produces monoclonal or bispecific antibodies that act directly on the patient. Additionally, it eliminates the cumbersome process of in vitro protein expression and extends the half-life of short-lived proteins, which significantly reduces the cost and duration of antibody production. This review focuses on the benefits and drawbacks of mRNA antibodies compared with the traditional in vitro expressed antibodies. In addition, it elucidates the progress of mRNA antibodies in the prevention of infectious diseases and oncology therapy.

Metabolic interventions improve HBV envelope-specific T-cell responses in patients with chronic hepatitis B

BACKGROUND

Restoration of HBV-specific T cell immunity is a promising approach for the functional cure of chronic Hepatitis B (CHB), necessitating the development of valid assays to boost and monitor HBV-specific T cell responses in patients with CHB.

METHODS

We analyzed hepatitis B virus (HBV) core- and envelope (env)-specific T cell responses using in vitro expanded peripheral blood mononuclear cells (PBMCs) from patients with CHB exhibiting different immunological phases, including immune tolerance (IT), immune activation (IA), inactive carrier (IC), and HBeAg-negative hepatitis (ENEG). Additionally, we evaluated the effects of metabolic interventions, including mitochondria-targeted antioxidants (MTA), polyphenolic compounds, and ACAT inhibitors (iACAT), on HBV-specific T-cell functionality.

RESULTS

We found that HBV core- and env-specific T cell responses were finely coordinated and more profound in IC and ENEG than in the IT and IA stages. HBV env-specific T cells were more dysfunctional but prone to respond to metabolic interventions using MTA, iACAT, and polyphenolic compounds than HBV core-specific T-cells. The responsiveness of HBV env-specific T cells to metabolic interventions can be predicted by the eosinophil (EO) count and the coefficient of variation of red blood cell distribution width (RDW-CV).

CONCLUSION

These findings may provide valuable information for metabolically invigorating HBV-specific T-cells to treat CHB.

Efficacy of antiviral therapy and host-virus interactions visualised using serial liver sampling with fine-needle aspirates

Background & Aims

Novel therapies for chronic hepatitis B (CHB), such as RNA interference, target all viral RNAs for degradation, whereas nucleoside analogues are thought to block reverse transcription with minimal impact on viral transcripts. However, limitations in technology and sampling frequency have been obstacles to measuring actual changes in HBV transcription in the liver of patients starting therapy.

Methods

We used elective liver sampling with fine-needle aspirates (FNAs) to investigate the impact of treatment on viral replication in patients with CHB. Liver FNAs were collected from patients with CHB at baseline and 12 and 24 weeks after starting tenofovir alafenamide treatment. Liver FNAs were subjected to single-cell RNA sequencing and analysed using the Viral-Track method.

Results

HBV was the only viral genome detected and was enriched within hepatocytes. The 5' sequencing technology identified protein-specific HBV transcripts and showed that tenofovir alafenamide therapy specifically reduced pre-genomic RNA transcripts with little impact on HBsAg or HBx transcripts. Infected hepatocytes displayed unique gene signatures associated with an immunological response to viral infection.

Conclusions

Longitudinal liver sampling, combined with single-cell RNA sequencing, captured the dynamic impact of antiviral therapy on the replication status of HBV and revealed host-pathogen interactions at the transcriptional level in infected hepatocytes. This sequencing-based approach is applicable to early-stage clinical studies, enabling mechanistic studies of immunopathology and the effect of novel therapeutic interventions.

Impact and Implications

Infection-dependent transcriptional changes and the impact of antiviral therapy on viral replication can be measured in longitudinal human liver biopsies using single-cell RNA sequencing data.

PreS1- targeting chimeric antigen receptor T cells diminish HBV infection in liver humanized FRG mice

Current therapies control but rarely achieve a cure for hepatitis B virus (HBV) infection. Restoration of the HBV-specific immunity by cell-based therapy represents a potential approach for a cure. In this study, we generated HBV specific CAR T cells based on an antibody 2H5-A14 targeting a preS1 region of the HBV large envelope protein. We show that the A14 CAR T cell is capable of killing hepatocytes infected by HBV with high specificity; adoptive transfer of A14 CAR T cells to HBV infected humanized FRG mice resulted in reductions of all serum and intrahepatic virological markers to levels below the detection limit. A14 CAR T cells treatment increased the levels of human IFN-γ, GM-CSF, and IL-8/CXCL-8 in the mice. These results show that A14 CAR T cells may be further developed for curative therapy against HBV infection by eliminating HBV-infected hepatocytes and inducing production of pro-inflammatory and antiviral cytokines.

Pathway to global elimination of hepatitis B: HBV cure is just the first step

Hepatitis B (HBV) is a major cause of global morbidity and mortality, and the leading cause of liver cancer worldwide. Significant advances have recently been made toward the development of a finite HBV treatment that achieves permanent loss of HBsAg and HBV DNA (so-called "HBV cure"), which could provide the means to eliminate HBV as a public health threat. However, the HBV cure is just one step toward achieving WHO HBV elimination targets by 2030, and much work must be done now to prepare for the successful implementation of the HBV cure. In this review, we describe the required steps to rapidly scale-up future HBV cure equitably. We present key actions required for successful HBV cure implementation, integrated within the World Health Organization (WHO) Global Health Sector Strategy (GHSS) 2022-2030 framework. Finally, we highlight what can be done now to progress toward the 2030 HBV elimination targets using available tools to ensure that we are preparing, but not waiting, for the cure.

Increased liver stiffness promotes hepatitis B progression by impairing innate immunity in CCl4-induced fibrotic HBV+ transgenic mice

Background

Hepatitis B virus (HBV) infection develops as an acute or chronic liver disease, which progresses from steatosis, hepatitis, and fibrosis to end-stage liver diseases such as cirrhosis and hepatocellular carcinoma (HCC). An increased stromal stiffness accompanies fibrosis in chronic liver diseases and is considered a strong predictor for disease progression. The goal of this study was to establish the mechanisms by which enhanced liver stiffness regulates HBV infectivity in the fibrotic liver tissue.

Methods

For in vitro studies, HBV-transfected HepG2.2.15 cells were cultured on polydimethylsiloxane gels coated by polyelectrolyte multilayer films of 2 kPa (soft) or 24 kPa (stiff) rigidity mimicking the stiffness of the healthy or fibrotic liver. For in vivo studies, hepatic fibrosis was induced in C57Bl/6 parental and HBV+ transgenic (HBVTg) mice by injecting CCl4 twice a week for 6 weeks.

Results

We found higher levels of HBV markers in stiff gel-attached hepatocytes accompanied by up-regulated OPN content in cell supernatants as well as suppression of anti-viral interferon-stimulated genes (ISGs). This indicates that pre-requisite "fibrotic" stiffness increases osteopontin (OPN) content and releases and suppresses anti-viral innate immunity, causing a subsequent rise in HBV markers expression in hepatocytes. In vitro results were corroborated by data from HBVTg mice administered CCl4 (HBVTg CCl4). These mice showed higher HBV RNA, DNA, HBV core antigen (HBcAg), and HBV surface antigen (HBsAg) levels after liver fibrosis induction as judged by a rise in Col1a1, SMA, MMPs, and TIMPs mRNAs and by increased liver stiffness. Importantly, CCl4-induced the pro-fibrotic activation of liver cells, and liver stiffness was higher in HBVTg mice compared with control mice. Elevation of HBV markers and OPN levels corresponded to decreased ISG activation in HBVTg CCl4 mice vs HBVTg control mice.

Conclusion

Based on our data, we conclude that liver stiffness enhances OPN levels to limit anti-viral ISG activation in hepatocytes and promote an increase in HBV infectivity, thereby contributing to end-stage liver disease progression.

Modeling suggests that virion production cycles within individual cells is key to understanding acute hepatitis B virus infection kinetics

Hepatitis B virus (HBV) infection kinetics in immunodeficient mice reconstituted with humanized livers from inoculation to steady state is highly dynamic despite the absence of an adaptive immune response. To recapitulate the multiphasic viral kinetic patterns, we developed an agent-based model that includes intracellular virion production cycles reflecting the cyclic nature of each individual virus lifecycle. The model fits the data well predicting an increase in production cycles initially starting with a long production cycle of 1 virion per 20 hours that gradually reaches 1 virion per hour after approximately 3-4 days before virion production increases dramatically to reach to a steady state rate of 4 virions per hour per cell. Together, modeling suggests that it is the cyclic nature of the virus lifecycle combined with an initial slow but increasing rate of HBV production from each cell that plays a role in generating the observed multiphasic HBV kinetic patterns in humanized mice.

Prevalence of occult hepatitis B virus infection in Egypt: a systematic review with meta-analysis

BACKGROUND

Occult hepatitis B virus (HBV) infection (OBI) is a major public health problem. The clinical importance of OBI stems from the fact that it can be transmitted to healthy individuals at extremely low viral load levels. Additionally, immunosuppression has the potential to trigger viral replication, which can result in life-threatening liver decompensation. Despite several studies examining the prevalence of OBI, the pooled prevalence of OBI in Egypt remains unknown, particularly among blood donors and high-risk individuals, to whom intervention should be targeted.

METHODS

A comprehensive literature search of the following databases was conducted from inception to October 2022 using the following keywords: occult hepatitis B virus infection or occult HBV infection or OBI and Egypt in MEDLINE [PubMed], Scopus, Google Scholar, and Web of Science. The review was conducted following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) Statement. I-squared and Cochran's Q were used to measure the heterogeneity between the studies, and based on the random effects model, results were reported as proportions (%) with a 95% confidence interval (CI). Analyses of subgroup analyses were conducted based on the target population. Sensitivity analyses were conducted using the leave-one-out approach to test the robustness of the results.

RESULTS

A total of 50 studies with 62 estimations of OBI were included, 19 in patients who were HBsAg-negative and anti-HBc-positive and 43 in patients who were HBsAg-negative. The highest prevalence (41%) was among multi-transfused patients according to  studies that report occult hepatitis B virus prevalence in an HBsAg-negative population, while the pooled prevalence of OBI among patients on hemodialysis, patients with chronic hepatitis C infection, patients with hepatocellular carcinoma (HCC), and patients with liver cirrhosis was 17%, 10%, 24%, and 13%, respectively. On the other hand, among studies that report OBI prevalence in HBsAg-negative and anti-HBc-positive individuals, the pooled prevalence of OBI among blood donors, patients with chronic hepatitis C infection, and patients with HCC was 12%, 15%, and 31%, respectively. Also, the majority of studies examining the genetic background of OBI have found that genotype D is the most prevalent.

CONCLUSION

 This study highlights the high prevalence in OBI among blood donors and high-risk populations in Egypt. The implementation of HBV nucleic acid amplification testing (NAT) may increase the safety of blood transfusions by excluding all HBV DNA-positive donations. However, the cost-effectiveness of these tests should be investigated.

Triple motif proteins 19 and 38 correlated with treatment responses and HBsAg clearance in HBeAg-negative chronic hepatitis B patients during peg-IFN-α therapy

OBJECTIVE

To investigate whether the expression of triple motif protein 19/38 (TRIM19/38) mRNA in peripheral blood mononuclear cells (PBMCs) of HBeAg-negative chronic hepatitis B virus (HBV) carriers is associated with the response to pegylated interferon alpha (peg-IFN-α) treatment and HBsAg clearance.

METHODS

In this prospective study, HBeAg-negative chronic HBV carriers treated with peg-IFN-α completed 48 weeks of follow-up. After treatment with peg-IFN-α, the patients were divided into responders (R group) and nonresponders (NR group) according to the changes in HBV DNA and HBsAg levels at week 48 of treatment. According to whether serum HBsAg loss or seroconversion occurred, the patients were divided into a serological response group (SR group) and a nonserological response group (NSR group). The level of TRIM19/38 mRNA in PBMCs was detected by real-time fluorescence quantitative PCR. The diagnostic performance of TRIM19/38 was analysed by calculating the receiver operating characteristic (ROC) curve and area under the ROC curve (AUC).

RESULTS

43 HBeAg-negative chronic HBV carriers, 35 untreated CHB patients and 19 healthy controls were enrolled in this study. We found that TRIM19/38 mRNA levels were significantly lower in untreated CHB patients than in healthy controls. In HBeAg-negative chronic HBV carriers who underwent prospective follow-up, TRIM19/38 mRNA levels were negatively correlated with HBV DNA and ALT at baseline. Among the patients treated with peg-IFN-α, 16 patients achieved a treatment response (R group) and 27 patients did not achieve a treatment response (NR group). Compared with baseline, HBsAg levels in the R group decreased significantly at 12 and 24 weeks of treatment; at the early stage of peg-IFN-α treatment, the dynamic changes in TRIM19/38 mRNA levels in the R and NR groups were different, and the TRIM19/38 mRNA levels in the R group were significantly higher than those in the NR group, especially at 24 weeks of treatment. ROC curve analysis showed that the changes in mRNA levels of TRIM19 and TRIM38 predicted the treatment response, with AUCs of 0.694 and 0.757, respectively. Among the patients treated with peg-IFN-α, 11 patients achieved a serological response (SR group) and 32 patients did not achieve a serological response (NSR group). Compared with baseline, HBsAg levels in the SR group decreased significantly at 12 and 24 weeks of treatment; TRIM19/38 mRNA levels were significantly higher in the SR group than in the NSR group at week 24.

CONCLUSION

The higher level of TRIM19/38 mRNA in PBMCs of HBeAg-negative chronic HBV carriers may be related to the early treatment effect of peg-IFN-α and HBsAg clearance. TRIM19 and TRIM38 have clinical significance in predicting virological response and guiding treatment regimens.

New Perspectives on Development of Curative Strategies for Chronic Hepatitis B

A functional cure of chronic hepatitis B defined as sustained hepatitis B surface antigen loss after finite course of therapy is rarely achieved with current therapy but is the goal of novel treatments. Understanding the virological and immunological mechanisms of hepatitis B virus persistence has enabled the identification of novel treatment targets, drug discovery, and the evaluation of novel agents in clinical trials. Lessons were learned from early phase 1 and phase 2 trials regarding the antiviral activity and safety profile of these agents. There is a strong rationale to combine agents to reduce viral replication, reduce viral antigen load, invigorate immune responses, and induce specific adaptive immune responses. Nucleos(t)ide analogs will likely remain an essential backbone of future combinations to control viral replication and prevent resistance to antiviral drugs. In this review, we discuss perspectives on approaches to achieving functional cure, with a review of virological and immunological strategies, highlighting challenges and unresolved questions with the various attempts to achieve cure, as well as exploring alternative endpoints such as partial cure and new noninvasive viral and immunological biomarkers to stratify patients and predict/monitor antiviral response.

Opportunities and considerations for studying liver disease with microphysiological systems on a chip

Advances in microsystem engineering have enabled the development of highly controlled models of the liver that better recapitulate the unique in vivo biological conditions. In just a few short years, substantial progress has been made in creating complex mono- and multi-cellular models that mimic key metabolic, structural, and oxygen gradients crucial for liver function. Here we review: 1) the state-of-the-art in liver-centric microphysiological systems and 2) the array of liver diseases and pressing biological and therapeutic challenges which could be investigated with these systems. The engineering community has unique opportunities to innovate with new liver-on-a-chip devices and partner with biomedical researchers to usher in a new era of understanding of the molecular and cellular contributors to liver diseases and identify and test rational therapeutic modalities.

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

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

Efficacy evaluation of direct antiviral drugs against hepatitis B virus in improving the degree of liver fibrosis

Introduction

The aim of the study was to find an ideal index reflecting inflammation and fibrosis for patients after antiviral treatment, and compare it with imaging examination (liver stiffness measurement - LSM) and traditional liver fibrosis models (APRI and FIB-4).

Material and methods

A total of 77 chronic hepatitis B (CHB) patients who achieved a sustained virological response (SVR) after entecavir (ETV) treatment were included, and the changes of various clinical indicators before and after treatment were compared.

Results

After 78 weeks of ETV treatment, WBC and PLT of 77 patients were significantly increased, while ALT, AST and total bilirubin were significantly decreased (p < 0.05). There was no significant difference in serum creatinine (Cr) or blood urea nitrogen (BUN) compared to the values before treatment (p > 0.05). The three non-invasive liver fibrosis indexes, namely, LSM, APRI and FIB-4, were significantly decreased in 77 patients compared to the values before treatment (p < 0.001).

Conclusions

Acoustic radiation force impulse (ARFI), fibrosis-4 (FIB-4), aspartate aminotransferase-to-platelet ratio index (APRI) have a high consistency with the grading of liver fibrosis, and can be used to evaluate the severity of liver fibrosis. Among them, ARFI has good diagnostic value for the classification of different degrees of liver fibrosis and the best diagnostic accuracy.

A Current Management Strategy for Children with Chronic Viral Hepatitis B, Based on International and National Guidelines

BACKGROUND

Peculiarities of the course of chronic viral hepatitis B in children cause an important medical and social problem of health care, despite the implementation of modern treatment and prevention protocols. Pathogenetic mechanisms of the development and progression of viral hepatitis B infection, the presence of occult poorly diagnosed form, the impossibility of completely eliminating the virus and the specificity of the immune response in children are still not fully solved scientific problems.

MATERIAL AND METHODS

The aim of this review is to examine current strategies for the diagnosis and treatment of chronic hepatitis B in children, based on international and national guidelines.

RESULTS

A detailed analysis of modern guidelines on the course and pathogenesis of viral hepatitis B infection confirms the fact that chronic hepatitis B is characterised by a complex interaction between the immune system of the virus and the patient, whose dynamic balance is not only responsible for the various phases of chronic viral hepatitis B infection but also leads to the result of antiviral treatment.

CONCLUSION

Despite the introduction of vaccination of children against hepatitis B, the level of viral hepatitis B vaccination of children in Ukraine remains insufficient, which leads to the further spread of the infection. Currently available antiviral drugs can provide functional treatment of viral hepatitis B infection in a limited number of patients, but today's Ukrainian realities have caused a change in approach to the treatment and monitoring of patients, which may negatively affect the implementation of the key goals of the World Health Organization Global Strategy on the prevention, diagnosis and treatment of viral hepatitis.

Clinicopathologic characteristics of liver inflammation and fibrosis in 310 patients with chronic hepatitis B

OBJECTIVES

Long-term hepatitis B virus (HBV) infection can cause recurrent inflammation in the liver, and then develop into liver fibrosis, cirrhosis, and liver cancer. The hepatic pathological change is one of the important criteria for guiding antiviral therapy in patients with chronic hepatitis B (CHB). Due to the limitations of liver biopsy, it is necessary to find valuable non-invasive indicators to evaluate the hepatic pathological changes in CHB patients and guide the antiviral therapy. This study aims to analyze the clinical characteristics of different pathological changes in CHB patients, and to explore the factors influnencing the degree of liver inflammation and fibrosis in CHB patients with normal alanine aminotransferase (ALT).

METHODS

This retrospective study was conducted on 310 CHB patients. Liver biopsy was performed in all these patients. The clinical data of the patients were collected. The liver biopsy pathological results were used as the gold standard to analyze the relationship between clinical indicators and liver pathological changes. Then CHB patients with normal ALT were screened, and the independent factors influencing the degree of liver inflammation and fibrosis were explored.

RESULTS

Among the 310 patients with CHB, there were 249 (80.3%) patients with significant liver inflammation [liver inflammation grade (G) ≥2] and 119 (38.4%) patients with significant liver fibrosis [liver fibrosis stage (S) ≥2]. The results of univariate analysis of total samples showed that the ALT, γ-glutamyl transferase, alkaline phosphatase, and HBV DNA were related to the significant liver pathological changes. Among the 132 CHB patients with normal ALT, the patients with liver pathology G/S≥2, G≥2, and S≥2 were 80.3% (106/132), 68.2% (90/132), and 43.2% (57/132), respectively. The results showed that the independent influencing factor of significant liver inflammation was HBV DNA>2 000 U/mL (OR=3.592, 95% CI 1.534 to 8.409), and the independent influencing factors of significant liver fibrosis were elevated alkaline phosphatase level (OR=1.022, 95% CI 1.002 to 1.043), decreased platelet count (OR=0.990, 95% CI 0.982 to 0.998), and positive in hepatitis B e antigen (HBeAg) (OR=14.845, 95% CI 4.898 to 44.995). According to the multivariate analysis, a diagnostic model for significant liver fibrosis in CHB patients with normal ALT was established, and the area under the receiver operating characteristic curve was 0.844 (95% CI 0.779 to 0.910).

CONCLUSIONS

The liver pathological changes should be evaluated in combination with different clinical indicators. A considerable number of CHB patients with normal ALT still have significant liver pathological changes, which need to be identified and treated with antiviral therapy in time. Among them, HBV DNA>2 000 U/mL suggests the significant liver inflammation, and the diagnostic model for significant liver fibrosis based on alkaline phosphatase, platelet count, and HBeAg can help to evaluate the degree of liver fibrosis.

Current and novel modalities for management of chronic hepatitis B infection

Over 296 million people are estimated to have chronic hepatitis B viral infection (CHB), and it poses unique challenges for elimination. CHB is the result of hepatitis B virus (HBV)-specific immune tolerance and the presence of covalently closed circular DNA as mini chromosome inside the nucleus and the integrated HBV. Serum hepatitis B core-related antigen is the best surrogate marker for intrahepatic covalently closed circular DNA. Functional HBV “cure” is the durable loss of hepatitis B surface antigen (HBsAg), with or without HBsAg seroconversion and undetectable serum HBV DNA after completing a course of treatment. The currently approved therapies are nucleos(t)ide analogues, interferon-alpha, and pegylated-interferon. With these therapies, functional cure can be achieved in < 10% of CHB patients. Any variation to HBV or the host immune system that disrupts the interaction between them can lead to reactivation of HBV. Novel therapies may allow efficient control of CHB. They include direct acting antivirals and immunomodulators. Reduction of the viral antigen load is a crucial factor for success of immune-based therapies. Immunomodulatory therapy may lead to modulation of the host immune system. It may enhance/restore innate immunity against HBV (as toll-like-receptors and cytosolic retinoic acid inducible gene I agonist). Others may induce adaptive immunity as checkpoint inhibitors, therapeutic HBV vaccines including protein (HBsAg/preS and hepatitis B core antigen), monoclonal or bispecific antibodies and genetically engineered T cells to generate chimeric antigen receptor-T or T-cell receptor-T cells and HBV-specific T cells to restore T cell function to efficiently clear HBV. Combined therapy may successfully overcome immune tolerance and lead to HBV control and cure. Immunotherapeutic approaches carry the risk of overshooting immune responses causing uncontrolled liver damage. The safety of any new curative therapies should be measured in relation to the excellent safety of currently approved nucleos(t)ide analogues. Development of novel antiviral and immune modulatory therapies should be associated with new diagnostic assays used to evaluate the effectiveness or to predict response.

The expression of interleukin-1β in patients with chronic hepatitis B treated with pegylated-interferon-alpha combined with tenofovir disoproxil fumarate and monotherapy

BACKGROUND

Anti-hepatitis B virus (HBV) treatment uses tenofovir disoproxil fumarate (TDF) along with Pegylated-interferon-alpha (Peg-IFN-α), which is more effective than TDF/Peg-IFN-α monotherapy. We have previously shown that interleukin-1beta (IL-1β) is related to the effectiveness of IFN-α treatment in chronic hepatitis B (CHB) patients. The aim was to investigate the expression of IL-1β in CHB patients treated with Peg-IFN-α combination with TDF and TDF/Peg-IFN-α monotherapy.

METHODS

Huh7 cells infected with HBV were stimulated by Peg-IFN-α and/or Tenofovir (TFV) for 24h. A single-center cohort study of prospective recruitment of CHB patients: untreated CHB (Group A), TDF combined with Peg-IFN-α therapy (Group B), Peg-IFN-α monotherapy (Group C), TDF monotherapy (Group D). Normal donors served as controls. The clinical datas and blood of patients were collected at 0, 12, and 24 weeks. According to the early response criteria, Group B and C were divided into two subgroups: the early response group (ERG) and the non-early response group (NERG). Stimulation of HBV-infected hepatoma cells with IL-1β to validate the antiviral activity of IL-1β. To test the blood sample, cell culture supernatant, and cell lysates and to assess the expression of IL-1β and HBV replication levels in various treatment protocols, Enzyme-Linked Immunosorbent Assay (ELISA) and quantitative reverse transcription polymerase chain reaction (qRT-PCR) were used. SPSS 26.0 and GraphPad Prism 8.0.2 software were used for statistical analysis. P values < 0.05 was considered to be statistically significant.

RESULTS

In vitro experiments, Peg-IFN-α plus TFV treatment group expressed higher IL-1β and inhibited HBV more effectively than monotherapy. Finally, 162 cases were enrolled for observation (Group A (n = 45), Group B (n = 46), Group C (n = 39), and Group D (n = 32)), and normal donors (n = 20) were enrolled for control. The early virological response rates of Group B, C, and D were 58.7%, 51.3%, and 31.2%. At 24 weeks, IL-1β in Group B(P = 0.007) and C(P = 0.034) showed higher than at 0 week. In Group B, the IL-1β showed an upward trend at 12w and 24w in the ERG. IL-1β significantly reduced HBV replication levels in hepatoma cells.

CONCLUSION

The increased expression of IL-1β may enhance the efficacy of TDF combined with Peg-IFN-α therapy in achieving an early response for CHB patients.

Transcriptomics based identification of S100A3 as the key anti-hepatitis B virus factor of 16F16

More than 250 million people worldwide have chronic hepatitis B virus (HBV) infections, resulting in over 1 million annual fatalities because HBV cannot be adequately treated with current antivirals. Hepatocellular carcinoma (HCC) risk is elevated in the presence of the HBV. Novel and powerful medications that specifically target the persistent viral components are needed to remove infection. This study aimed to use HepG2.2.15 cells and the rAAV-HBV1.3 C57BL/6 mouse model established in our laboratory to examine the effects of 16F16 on HBV. The transcriptome analysis of the samples was performed to examine the impact of 16F16 therapy on host factors. We found that the HBsAg and HBeAg levels significantly decreased in a dose-dependent manner following the 16F16 treatment. 16F16 also showed significant anti-hepatitis B effects in vivo. The transcriptome analysis showed that 16F16 regulated the expression of several proteins in HBV-producing HepG2.2.15 cells. As one of the differentially expressed genes, the role of S100A3 in the anti-hepatitis B process of 16F16 was further investigated. The expression of the S100A3 protein significantly decreased following the 16F16 therapy. And upregulation of S100A3 caused an upregulation of HBV DNA, HBsAg, and HBeAg in HepG2.2.15 cells. Similarly, knockdown of S100A3 significantly reduced the levels of HBsAg, HBeAg, and HBV DNA. Our findings proved that S100A3 might be a new target for combating HBV pathogenesis. 16F16 can target several proteins involved in HBV pathogenesis, and may be a promising drug precursor molecule for the treatment of HBV.

The Role of CTLA-4 in T Cell Exhaustion in Chronic Hepatitis B Virus Infection

Patients with chronic hepatitis B (CHB) gradually develop T cell exhaustion, and the inhibitory receptor molecule, cytotoxic T-lymphocyte antigen-4 (CTLA-4), may play a role in this phenomenon. This systematic review investigates the role of CTLA-4 in the development of T cell exhaustion in CHB. A systematic literature search was conducted on PubMed and Embase on 31 March 2023 to identify relevant studies. Fifteen studies were included in this review. A majority of the studies investigating CD8⁺ T cells demonstrated increased expression of CTLA-4 in CHB patients, though one study found this only in HBeAg-positive patients. Three out of four studies investigating the expression of CTLA-4 on CD4⁺ T cells found upregulation of CTLA-4. Several studies showed constitutive expression of CLTA-4 on CD4⁺ regulatory T cells. CTLA-4 blockade resulted in heterogeneous responses for all T cell types, as it resulted in increased T cell proliferation and/or cytokine production in some studies, while other studies found this only when combining blockade of CTLA-4 with other inhibitory receptors. Although mounting evidence supports a role of CTLA-4 in T cell exhaustion, there is still insufficient documentation to describe the expression and exact role of CTLA-4 in T cell exhaustion in CHB.

Quantification of the hepatitis B virus cccDNA: evidence-based guidelines for monitoring the key obstacle of HBV cure

OBJECTIVES

A major goal of curative hepatitis B virus (HBV) treatments is the reduction or inactivation of intrahepatic viral covalently closed circular DNA (cccDNA). Hence, precise cccDNA quantification is essential in preclinical and clinical studies. Southern blot (SB) permits cccDNA visualisation but lacks sensitivity and is very laborious. Quantitative PCR (qPCR) has no such limitations but inaccurate quantification due to codetection of viral replicative intermediates (RI) can occur. The use of different samples, preservation conditions, DNA extraction, nuclease digestion methods and qPCR strategies has hindered standardisation. Within the ICE-HBV consortium, available and novel protocols for cccDNA isolation and qPCR quantification in liver tissues and cell cultures were compared in six laboratories to develop evidence-based guidance for best practices.

DESIGN

Reference material (HBV-infected humanised mouse livers and HepG2-NTCP cells) was exchanged for cross-validation. Each group compared different DNA extraction methods (Hirt extraction, total DNA extraction with or without proteinase K treatment (+PK/-PK)) and nuclease digestion protocols (plasmid-safe ATP-dependent DNase (PSD), T5 exonuclease, exonucleases I/III). Samples were analysed by qPCR and SB.

RESULTS

Hirt and -PK extraction reduced coexisting RI forms. However, both cccDNA and the protein-free relaxed circular HBV DNA (pf-rcDNA) form were detected by qPCR. T5 and Exo I/III nucleases efficiently removed all RI forms. In contrast, PSD did not digest pf-rcDNA, but was less prone to induce cccDNA overdigestion. In stabilised tissues (eg, Allprotect), nucleases had detrimental effects on cccDNA.

CONCLUSIONS

We present here a comprehensive evidence-based guidance for optimising, controlling and validating cccDNA measurements using available qPCR assays.

Forthcoming Developments in Models to Study the Hepatitis B Virus Replication Cycle, Pathogenesis, and Pharmacological Advancements

Hepatitis, liver cirrhosis, and hepatocellular carcinoma are all manifestations of chronic hepatitis B. Its pathogenesis and molecular mechanism remain mysterious. As medical science progresses, different models are being used to study the disease from the physiological and molecular levels. Animal models have played an unprecedented role in achieving in-depth knowledge of the disease while posing no risk of harming humans throughout the study. The scarcity of acceptable animal models has slowed progress in hepatitis B virus (HBV) research and preclinical testing of antiviral medicines since HBV has a narrow species tropism and exclusively infects humans and higher primates. The development of human chimeric mice was supported by a better understanding of the obstacles to interspecies transmission, which has substantially opened the way for HBV research in vivo and the evaluation of possible chronic hepatitis B therapeutics. Animal models are cumbersome to handle, not accessible, and expensive. Hence, it is herculean to investigate the HBV replication cycle in animal models. Therefore, it becomes essential to build a splendid in vitro cell culture system to demonstrate the mechanisms attained by the HBV for its multiplication and sustenance. We also addressed the advantages and caveats associated with different models in examining HBV.

Emerging drugs for hepatitis D

INTRODUCTION

Chronic hepatitis delta (CHD) is the most severe form of chronic viral hepatitis. Until recently, its treatment consisted of pegylated interferon alfa (pegIFN) use.

AREAS COVERED

Current and new drugs for treating CHD. Virus entry inhibitor bulevirtide has received conditional approval by the European Medicines Agency. Prenylation inhibitor lonafarnib and pegIFN lambda are in phase 3 and nucleic acid polymers in phase 2 of drug development.

EXPERT OPINION

Bulevirtide appears to be safe. Its antiviral efficacy increases with treatment duration. Combining bulevirtide with pegIFN has the highest antiviral efficacy short-term. The prenylation inhibitor lonafarnib prevents hepatitis D virus assembly. It is associated with dose dependent gastrointestinal toxicity and is better used with ritonavir which increases liver lonafarnib concentrations. Lonafarnib also possesses immune modulatory properties which explains some post-treatment beneficial flare cases. Combining lonafarnib/ritonavir with pegIFN has superior antiviral efficacy. Nucleic acid polymers are amphipathic oligonucleotides whose effect appears to be a consequence of phosphorothioate modification of internucleotide linkages. These compounds led to HBsAg clearance in a sizeable proportion of patients. PegIFN lambda is associated with less IFN typical side effects. In a phase 2 study it led to 6 months off treatment viral response in one third of patients.

HBV Infection and Host Interactions: The Role in Viral Persistence and Oncogenesis

Hepatitis B virus (HBV) is a major cause of chronic hepatitis, liver cirrhosis, and hepatocellular carcinoma. Despite the advent of vaccines and potent antiviral agents able to suppress viral replication, recovery from chronic HBV infection is still an extremely difficult goal to achieve. Complex interactions between virus and host are responsible for HBV persistence and the risk of oncogenesis. Through multiple pathways, HBV is able to silence both innate and adaptive immunological responses and become out of control. Furthermore, the integration of the viral genome into that of the host and the production of covalently closed circular DNA (cccDNA) represent reservoirs of viral persistence and account for the difficult eradication of the infection. An adequate knowledge of the virus-host interaction mechanisms responsible for viral persistence and the risk of hepatocarcinogenesis is necessary for the development of functional cures for chronic HBV infection. The purpose of this review is, therefore, to analyze how interactions between HBV and host concur in the mechanisms of infection, persistence, and oncogenesis and what are the implications and the therapeutic perspectives that follow.

Lipid phosphatase SAC1 suppresses hepatitis B virus replication through promoting autophagic degradation of virions

Phosphatidylinositol lipids play vital roles in lipid signal transduction, membrane recognition, vesicle transport, and viral replication. Previous studies have revealed that SAC1-like phosphatidylinositol phosphatase (SACM1L/SAC1), which uses phosphatidylinositol-4-phosphate (PI4P) as its substrate, greatly affects the replication of certain bacteria and viruses in vitro. However, it remains unclear whether and how SAC1 modulates hepatitis B virus (HBV) replication in vitro and in vivo. In the present study, we observed that SAC1 silencing significantly increased HBV DNA replication, subviral particle (SVP) expression, and secretion of HBV virions, whereas SAC1 overexpression exerted the opposite effects. Moreover, SAC1 overexpression inhibited HBV DNA replication and SVP expression in a hydrodynamic injection-based HBV-persistent replicating mouse model. Mechanistically, SAC1 silencing increased the number of HBV-containing autophagosomes as well as PI4P levels on the autophagosome membrane. Moreover, SAC1 silencing blocked autophagosome-lysosome fusion by inhibiting the interaction between synaptosomal-associated protein 29 and vesicle-associated membrane protein 8. Collectively, our data indicate that SAC1 significantly inhibits HBV replication by promoting the autophagic degradation of HBV virions. Our findings support that SAC1-mediated phospholipid metabolism greatly modulates certain steps of the HBV life-cycle and provide a new theoretical basis for antiviral therapy.

An RNA-based system to study hepatitis B virus replication and evaluate antivirals

Hepatitis B virus (HBV) chronically infects an estimated 300 million people, and standard treatments are rarely curative. Infection increases the risk of liver cirrhosis and hepatocellular carcinoma, and consequently, nearly 1 million people die each year from chronic hepatitis B. Tools and approaches that bring insights into HBV biology and facilitate the discovery and evaluation of antiviral drugs are in demand. Here, we describe a method to initiate the replication of HBV, a DNA virus, using synthetic RNA. This approach eliminates contaminating background signals from input virus or plasmid DNA that plagues existing systems and can be used to study multiple stages of HBV replication. We further demonstrate that this method can be uniquely applied to identify sequence variants that confer resistance to antiviral drugs.

TLR7 agonist RO7020531 versus placebo in healthy volunteers and patients with chronic hepatitis B virus infection: a randomised, observer-blind, placebo-controlled, phase 1 trial

BACKGROUND

Toll-like receptor 7 (TLR7) agonists augment immune activity and have potential for the treatment of chronic hepatitis B virus (HBV) infection. We aimed to assess the safety and tolerability of RO7020531 (also called RG7854), a prodrug of the TLR7 agonist RO7011785, in healthy volunteers and patients with chronic HBV infection.

METHODS

This randomised, observer-blind, placebo-controlled, phase 1 study was done in two parts. Part 1 was done at one site in New Zealand and part 2 was done at 12 sites in Bulgaria, Hong Kong, Italy, New Zealand, the Netherlands, Taiwan, Thailand, and the UK. In part 1, healthy volunteers were randomly assigned (4:1) within one of eight dose cohorts (3 mg, 10 mg, 20 mg, 40 mg, 60 mg, 100 mg, 140 mg, or 170 mg) to receive a single RO7020531 dose or placebo or randomly assigned (4:1) within one of three dose cohorts (100 mg, 140 mg, or 170 mg) to receive either RO7020531 or placebo every other day for 13 days. In part 2, nucleoside or nucleotide analogue-suppressed patients with chronic HBV infection were randomly assigned (4:1) within cohorts 1-3 (150 mg, 150 mg, or 170 mg) to receive either RO7020531 or placebo and treatment-naive patients with chronic HBV infection were randomly assigned (3:1) in cohort 4 to receive either 150 mg of RO7020531 or placebo. Patients were treated every other day for 6 weeks. Study medication was administered orally to participants after they had fasted. Study participants and investigational staff were masked to treatment allocation. The primary outcome was the safety and tolerability of RO7020531, as measured by the incidence and severity of adverse events and the incidence of laboratory, vital sign, and electrocardiogram abnormalities, and was analysed in all participants who received at least one dose of the study medication. This trial is registered with ClinicalTrials.gov, NCT02956850, and the study is complete.

FINDINGS

Between Dec 12, 2016, and March 21, 2021, 340 healthy volunteers were screened in part 1, of whom 80 were randomly assigned in the single ascending dose study (eight assigned RO7020531 in each cohort and 16 assigned placebo) and 30 were randomly assigned in the multiple ascending dose study (eight assigned RO7020531 in each cohort and six assigned placebo), and 110 patients were screened in part 2, of whom 30 were randomly assigned in cohorts 1-3 (16 assigned RO7020531 150 mg, eight assigned RO7020531 170 mg, and six assigned placebo) and 20 were randomly assigned in cohort 4 (15 assigned RO7020531 and five assigned placebo). All randomly assigned participants received at least one dose of a study drug and were included in the safety analysis. All tested doses of RO7020531 were safe and had acceptable tolerability in healthy volunteers and patients. The most frequent treatment-related adverse events among the total study population were headache (15 [9%] of 160 participants), influenza-like illness (seven [4%] of 160 participants), and pyrexia (ten [6%] of 160 participants). Most adverse events were mild and transient. There were no severe or serious adverse events in healthy volunteers. In the patient cohorts, there was one severe adverse event (influenza-like illness with 170 mg of RO7020531) and one serious adverse event (moderate influenza-like illness with a 3-day hospitalisation in a treatment-naive patient receiving RO7020531). There were no treatment-related deaths.

INTERPRETATION

Due to acceptable safety and tolerability, RO7020531 should continue to be developed for the treatment of patients with chronic HBV infection.

FUNDING

F Hoffmann-La Roche.

Serum HBV RNA is associated with liver fibrosis regression in HBeAg-positive chronic hepatitis B patients treated with nucleos(t)ide analogues

Noninvasive methods for assessing hepatic fibrosis are clinically necessary. This study aims to explore HBV markers correlated with liver fibrosis and capable of diagnosing significant fibrosis and predicting fibrosis regression. Seventy-four HBeAg-positive chronic hepatitis B (CHB) patients were enrolled and started on entecavir or adefovir therapy. Serum HBV RNA, HBV DNA, HBsAg and hepatitis B core-related antigen (HBcrAg) levels were measured at baseline and during treatment. Liver fibrosis was assessed at baseline and month 60 by liver biopsy. Fibrosis regression was defined as Ishak fibrosis score decreased ≥1-point. At baseline, HBsAg, HBcrAg and HBV RNA levels had a stronger correlation with Ishak fibrosis score (r = -.441, p = .002; r = -.469, p = .001; r = -.398, p = .001) than APRI and FIB-4 (r = .321 p = .006; r = .371, p = .001). HBsAg >4 log₁₀ IU/ml plus HBcrAg >7 log₁₀ IU/ml or HBsAg >4 log₁₀ IU/ml plus HBV RNA >5 log₁₀ copies/ml exhibited the same excellent diagnostic ability for significant fibrosis with the AUROC of 0.857. After 60 months of antiviral treatment, 66.7% of patients who suffered significant fibrosis at baseline achieved fibrosis regression, and an HBV RNA decline from baseline to month 6 greater than 0.63 log₁₀ copies/ml could predict the fibrosis regression at month 60. In conclusion, serum HBsAg, HBcrAg and HBV RNA are potential markers for predicting significant liver fibrosis. HBV RNA measurement would be particularly useful for monitoring hepatic fibrosis changes in HBeAg-positive CHB patients.

Limited disassembly of cytoplasmic hepatitis B virus nucleocapsids restricts viral infection in murine hepatic cells

BACKGROUND AND AIMS

Murine hepatic cells cannot support hepatitis B virus (HBV) infection even with supplemental expression of viral receptor, human sodium taurocholate cotransporting polypeptide (hNTCP). However, the specific restricted step remains elusive. In this study, we aimed to dissect HBV infection process in murine hepatic cells.

APPROACH AND RESULTS

Cells expressing hNTCP were inoculated with HBV or hepatitis delta virus (HDV). HBV pregenomic RNA (pgRNA), covalently closed circular DNA (cccDNA), and different relaxed circular DNA (rcDNA) intermediates were produced in vitro . The repair process from rcDNA to cccDNA was assayed by in vitro repair experiments and in mouse with hydrodynamic injection. Southern blotting and in situ hybridization were used to detect HBV DNA. HBV, but not its satellite virus HDV, was restricted from productive infection in murine hepatic cells expressing hNTCP. Transfection of HBV pgRNA could establish HBV replication in human, but not in murine, hepatic cells. HBV replication-competent plasmid, cccDNA, and recombinant cccDNA could support HBV transcription in murine hepatic cells. Different rcDNA intermediates could be repaired to form cccDNA both in vitro and in vivo . In addition, rcDNA could be detected in the nucleus of murine hepatic cells, but cccDNA could not be formed. Interestingly, nuclease sensitivity assay showed that the protein-linked rcDNA isolated from cytoplasm was completely nuclease resistant in murine, but not in human, hepatic cells.

CONCLUSIONS

Our results imply that the disassembly of cytoplasmic HBV nucleocapsids is restricted in murine hepatic cells. Overcoming this limitation may help to establish an HBV infection mouse model.

Serum HBsAg and HBcrAg is associated with inflammation in HBeAg-positive chronic hepatitis B patients

Backgrounds &amp; aims

Liver inflammation is the main risk factor for developing liver fibrosis, cirrhosis, and even hepatocellular carcinoma in chronic hepatitis B (CHB) patients. To replace biopsy, additional non-invasive biomarkers to diagnose and grade liver necroinflammation are urgently required in clinical practice.

Method

Ninety-four CHB patients, including 74 HBeAg-positive and 20 HBeAg-negative patients, were enrolled and started entecavir or adefovir therapy. Serum HBV RNA, HBV DNA, HBsAg, hepatitis B core-related antigen (HBcrAg), ALT and AST levels, as well as intrahepatic HBV DNA and cccDNA were measured at baseline and during treatment. Liver inflammation was assessed at baseline and month 60 by liver biopsy. Inflammation regression was defined as a ≥1-grade decrease according to the Scheuer scoring system.

Results

In HBeAg-positive CHB patients, at baseline, serum HBsAg and HBcrAg levels negatively correlated with inflammation grade, while ALT and AST levels positively correlated with inflammation grade. AST plus HBsAg exhibited excellent diagnostic ability for significant inflammation with an AUROC of 0.896. After 60 months of antiviral treatment, almost all the patients’ liver inflammation ameliorated to G1, and no patients had inflammation progression.

Conclusion

Besides ALT and AST, serum HBsAg and HBcrAg correlated with inflammation grade in HBeAg-positive CHB patients before NAs treatment. Moreover, the combination of HBsAg and AST exhibited excellent diagnostic ability for significant inflammation.

Seroprevalence of hepatitis B virus surface antigen (HBsAg) in Egypt (2000-2022): a systematic review with meta-analysis

BACKGROUND

Hepatitis B infection seriously threatens global public health, especially in developing nations. Despite several investigations on HBV incidence, the national pooled prevalence remains unknown, particularly in populations at-risk at whom interventions should be primarily aimed.

METHODS

A comprehensive literature search of the following databases: Medline [PubMed], Scopus, Google Scholar, and Web of Science was conducted following the PRISMA guidelines. I-squared and Cochran's Q were used to measure the heterogeneity between the studies. Publications that matched the following were included: Primary studies published in Egypt from 2000 to 2022 reported HBV prevalence based on HBsAg. We excluded any studies that were not performed on Egyptians or that were performed on patients suspected of acute viral hepatitis or studies focusing on occult hepatitis or vaccination evaluation studies, or national surveys.

RESULTS

The systematic review included 68 eligible studies reporting a total of 82 incidences of HBV infection based on hepatitis B surface antigen with a total sample size of 862,037. The pooled national prevalence among studies was estimated to be 3.67% [95% CI; 3: 4.39]. Children under 20 with a history of HBV vaccination during infancy had the lowest prevalence of 0.69%. The pooled prevalence of HBV infection among pregnant women, blood donors, and healthcare workers was 2.95%, 1.8%, and 1.1%, respectively. While patients with hemolytic anemia and hemodialysis patients, patients with malignancies, HCC patients, and chronic liver disease patients had the highest prevalences at 6.34%, 25.5%, 18.6%, and 34%, respectively. Studies reporting HBV prevalence in urban settings compared to rural settings revealed a similar HBV prevalence of 2.43% and 2.15%, respectively. Studies comparing HBV prevalence in males and females revealed a higher prevalence among males (3.75%) than females (2.2%).

CONCLUSION

In Egypt, hepatitis B infection is a significant public health issue. The blocking of mother-to-infant hepatitis B transmission, the scaling up of the scope of the existing vaccination program, and implementing new strategies, including screen-and-treat, may reduce the prevalence of the disease.

Overview of the development of HBV small molecule inhibitors

Like tuberculosis and Acquired Immune Deficiency Syndrome (AIDS), hepatitis B is a globally recognized major public health threat. Although there are many small-molecule drugs for the treatment of hepatitis B, the approved drugs cannot eradicate the pathogenic culprit covalently closed circular DNA in patients, so the patients need long-term medication to control HBV amplification. Driven by a high unmet medical need, many pharmaceutical companies and research institutions have been engaged in the development of anti-HBV drugs to achieve a functional cure for chronic hepatitis B as soon as possible. This review summarizes the pathogenesis of hepatitis B virus and the research progress in the development of anti-HBV small molecule drugs, and introduces the cccDNA formation and transcription inhibitors and core inhibitors in detail, especially emphasizes the role of chinese herbal medicine in the treatment of chronic hepatitis B. Furthermore, this review proposes three potential strategies for cccDNA eradication in the future. We believe this review will provide meaningful guidance to achieve a functional cure for viral hepatitis B in the future.

Plasma cytokine profile in occult HBV-infected blood donors

Aim: Cytokine profile in occult HBV infection (OBI) was systematically investigated to identify the immunopathogenesis of OBI. Materials & methods: A total of 46 OBI, ten asymptomatic hepatitis B surface antigen carriers, ten chronic hepatitis B and 12 healthy blood donors were recruited. A total of 21 plasma cytokines were detected. Results: Compared with healthy blood donors, elevated plasma Th1, Th2, Th17 and immune regulatory associated cytokines were observed in OBI. Almost no significant difference was found for these cytokines among OBI, asymptomatic hepatitis B surface antigen carriers and chronic hepatitis B. OBI displayed the predominance of type 2 and regulatory immunity. Conclusion: OBI displayed the general cytokine profile of chronic HBV infection, which might contribute to virus persistence and the presence of the liver microinflammatory environment. The clinical implications of OBI deserve more attention.

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.

Screening of an epigenetic compound library identifies BRD4 as a potential antiviral target for hepatitis B virus covalently closed circular DNA transcription

HBV cccDNA is the persistent form of viral genome, which exists in host cell nucleus as an episomal minichromosome decorated with histone and non-histone proteins. cccDNA is the authentic viral transcription template and resistant to current antivirals. Growing evidence shows that the transcriptional activity of cccDNA minichromosome undergoes epigenetic regulations, suggesting a new perspective for anti-cccDNA drug development through targeting histone modifications. In this study, we screened an epigenetic compound library in the cccDNA reporter cell line HepBHAe82, which produces the HA-tagged HBeAg in a cccDNA-dependent manner. Among the obtained hits, a bromodomain-containing protein 4 (BRD4) inhibitor MS436 exhibited marked inhibition of cccDNA transcription in both HBV stable cell line HepAD38 and HepG2-NTCP or primary human hepatocyte infection system under noncytotoxic concentrations. Chromatin immunoprecipitation (ChIP) assay demonstrated that MS436 dramatically reduced the enrichment of H3K27ac, an activating histone modification pattern, on cccDNA minichromosome. RNAseq differential analysis showed that MS436 does not drastically change host transcriptome or induce any known anti-HBV factors/pathways, indicating a direct antiviral effect of MS436 on cccDNA minichromosome. Interestingly, the MS436-mediated inhibition of cccDNA transcription is accompanied by cccDNA destabilization in HBV infection and a recombinant cccDNA system, indicating that BRD4 activity may also play a role in cccDNA maintenance. Furthermore, depletion of BRD4 by siRNA knockdown or PROTAC degrader resulted in cccDNA inhibition in HBV-infected HepG2-NTCP cells, further validating BRD4 as an antiviral target. Taken together, our study has demonstrated the practicability of HepBHAe82-based anti-HBV drug screening system and provided a proof-of-concept for targeting HBV cccDNA with epigenetic compounds.

An Ideal Hallmark Closest to Complete Cure of Chronic Hepatitis B Patients: High-sensitivity Quantitative HBsAg Loss

In the era of antiviral therapy, the main goal of treatment has shifted from the persistent inhibition of hepatitis B virus (HBV) replication to the pursuit of serological clearance of HBs surface antigen (HBsAg). Based on the life cycle of HBV, HBsAg originates from covalently closed circular DNA (cccDNA) and integrated HBV DNA, thus reflecting their transcriptional activity. Complete HBsAg loss may mean elimination or persistent inactivity of the HBV genome including cccDNA and integrated HBV DNA. HBsAg loss improves the recovery of abnormal immune function, which in turn, may further promote the clearance of residual viruses. Combined with functional cure and the great improvement of clinical outcomes, the continuous seroclearance of high-sensitivity quantitative HBsAg may represent the complete cure of chronic hepatitis B (CHB). For many other risk factors besides HBV itself, patients with HBsAg loss still need regular monitoring. In this review, we summarized the evolution of CHB treatment, the origin of serum HBsAg, the pattern of HBsAg seroclearance, and the effect of HBsAg loss on immune function and disease outcomes. In addition, we discuss the significance of high-sensitivity HBsAg detection and its possibility as a surrogate of complete cure.

PPIases Par14/Par17 Affect HBV Replication in Multiple Ways

Human parvulin 14 (Par14) and parvulin 17 (Par17) are peptidyl-prolyl cis/trans isomerases that upregulate hepatitis B virus (HBV) replication by binding to the conserved ¹³³Arg-Pro¹³⁴ (RP) motif of HBc and core particles, and ¹⁹RP²⁰-²⁸RP²⁹ motifs of HBx. In the absence of HBx, Par14/Par17 have no effect on HBV replication. Interaction with Par14/Par17 enhances the stability of HBx, core particles, and HBc. Par14/Par17 binds outside and inside core particles and is involved in HBc dimer-dimer interaction to facilitate core particle assembly. Although HBc RP motif is important for HBV replication, R133 residue is solely important for its interaction with Par14/Par17. Interaction of Par14 and Par17 with HBx involves two substrate-binding residues, Glu46/Asp74 (E46/D74) and E71/D99, respectively, and promotes HBx translocation to the nucleus and mitochondria. In the presence of HBx, Par14/Par17 are efficiently recruited to cccDNA and promote transcriptional activation via specific DNA-binding residues Ser19/44 (S19/44). S19 and E46/D74 of Par14, and S44 and E71/D99 of Par17, are also involved in the recruitment of HBc onto cccDNA. Par14/Par17 upregulate HBV replication via various effects that are mediated in part through the HBx-Par14/Par17-cccDNA complex and triple HBc, Par14/Par17, and cccDNA interactions in the nucleus, as well as via core particle-Par14/Par17 interactions in the cytoplasm.

Depleting hepatitis B virus relaxed circular DNA is necessary for resolution of infection by CRISPR-Cas9

CRISPR-Cas9 systems can directly target the hepatitis B virus (HBV) major genomic form, covalently closed circular DNA (cccDNA), for decay and demonstrate remarkable anti-HBV activity. Here, we demonstrate that CRISPR-Cas9-mediated inactivation of HBV cccDNA, frequently regarded as the "holy grail" of viral persistence, is not sufficient for curing infection. Instead, HBV replication rapidly rebounds because of de novo formation of HBV cccDNA from its precursor, HBV relaxed circular DNA (rcDNA). However, depleting HBV rcDNA before CRISPR-Cas9 ribonucleoprotein (RNP) delivery prevents viral rebound and promotes resolution of HBV infection. These findings provide the groundwork for developing approaches for a virological cure of HBV infection by a single dose of short-lived CRISPR-Cas9 RNPs. Blocking cccDNA replenishment and re-establishment from rcDNA conversion is critical for completely clearing the virus from infected cells by site-specific nucleases. The latter can be achieved by widely used reverse transcriptase inhibitors.

Nonproductive Hepatitis B Virus Covalently Closed Circular DNA Generates HBx-Related Transcripts from the HBx/Enhancer I Region and Acquires Reactivation by Superinfection in Single Cells

Hepatitis B virus (HBV) infection remains a public health problem worldwide. Persistent HBV infection relies on active transcription of the covalently closed circular DNA (cccDNA) in hepatocytes, which is less understood at the single-cell level. In this study, we isolated primary human hepatocytes from liver-humanized FRG mice infected with HBV and examined cccDNA transcripts in single cells based on 5' end sequencing. Our 5' transcriptome sequencing (RNA-seq) analysis unambiguously assigns different viral transcripts with overlapping 3' sequences and quantitatively measures viral transcripts for structural genes (3.5 kb, 2.4 kb, and 2.1 kb) and the nonstructural X gene (0.7 kb and related) in single cells. We found that an infected cell either can generate all viral transcripts, signifying active transcription, or presents only transcripts from the X gene and its associated enhancer I domain and no structural gene transcripts. Results from cell infection assays with recombinant HBV show that nonproductive transcription of cccDNA can be activated by incoming virus through superinfection. Moreover, upon HBV infection, cccDNA apparently can be transcribed in the absence of HBx and produces HBx, needed for productive transcription of other viral genes. These results shed new light on cccDNA transcription at the single-cell level and provide insights useful for improving the treatment strategy against chronic HBV infection. IMPORTANCE Hepatitis B virus (HBV) infection can be effectively suppressed but rarely cured by available drugs. Chronic HBV infection is based on persistence of covalently closed circular DNA (cccDNA) and continuous infection and reinfection with HBV in the liver. Understanding transcriptional regulation of cccDNA will help to achieve permanent transcriptional silencing, i.e., functional cure of HBV. In our study, we found that an infected cell either can generate all viral transcripts, signifying active transcription, or presents only transcripts from the X gene and its associated enhancer I domain and no structural gene transcripts. The nonproductive transcription of cccDNA can be activated by incoming virus through superinfection. Upon an infection, cccDNA apparently can be transcribed in the absence of HBx to produce HBx, necessary for subsequent transcription of other HBV genes. Our studies shed new light on the mechanism of HBV infection and may have implications for a functional cure regimen for HBV.