The Role of cccDNA in HBV Maintenance. Viruses. 2017;9:156. [PMID: 28635668 PMCID: PMC5490831 DOI: 10.3390/v9060156]

Elimination of the hepatitis B virus: A goal, a challenge

The hepatitis B elimination is a goal proposed by the WHO to be achieved by 2030 through the adoption of synergistic measures for the prevention and chronic HBV infection treatment. Complete cure is characterized by the HBV elimination from the body and is the goal of the chronic hepatitis B treatment, which once achieved, will enable the hepatitis B elimination. This, today, has been a scientific challenge. The difficulty in achieving a complete cure is due to the indefinite maintenance of a covalently closed episomal circular DNA (cccDNA) reservoir and the maintenance and persistence of an insufficient and dysfunctional immune response in chronically infected patients. Among the measures adopted to eliminate hepatitis B, two have the potential to directly interfere with the virus cycle, but with limited effect on HBV control. These are conventional vaccines-blocking transmission and antiviral therapy-inhibiting replication. Vaccines, despite their effectiveness in protecting against horizontal transmission and preventing mother-to-child vertical transmission, have no effect on chronic infection or potential to eliminate the virus. Treatment with antivirals suppresses viral replication, but has no curative effect, as it has no action against cccDNA. Therapeutic vaccines comprise an additional approach in the chronic infection treatment, however, they have only a modest effect on the immune system, enhancing it temporarily. This manuscript aims to address (1) the cccDNA persistence in the hepatocyte nucleus and the immune response dysfunction in chronically infected individuals as two primary factors that have hampered the treatment and HBV elimination from the human body; (2) the limitations of antiviral therapy and therapeutic vaccines, as strategies to control hepatitis B; and (3) the possibly promising therapeutic approaches for the complete cure and elimination of hepatitis B.

Risk factors related to low-level viraemia in chronic hepatitis B patients receiving entecavir treatment

Background

About 20% of on-treatment patients with chronic hepatitis B (CHB) experienced low-level viraemia (LLV), which is associated with persistent low-grade inflammation, fibrosis progression, and increased risk of hepatocellular carcinoma. We aimed to investigate the high-risk factors related to LLV.

Methods

In this retrospective study, patients receiving entecavir (ETV) treatment from January 2018 to January 2023 were enrolled, and were divided into a LLV (HBV DNA 20-2000 IU/mL) cohort and a complete virological response (CVR) (HBV DNA < 20 IU/mL) cohort according to the virological response at week 48 posttreatment. Treatment baseline characteristics were retrieved from electronic medical records. Multivariate logistic regression was performed.

Results

Totally, 1653 patients were enrolled, male patients accounted for 73.0%; the median age was 44 years; the mean HBV DNA level was 5.9 Log10 IU/ml. Among them, 472 (28.6%) experienced LLV. Multivariate analysis showed that HBeAg positivity (OR = 2.650, 95% CI: 2.000-3.511, p < 0.001), HBV DNA ≥ 6.0 Log10 IU/mL (OR = 1.370, 95% CI: 1.054-1.780, p = 0.019), qHBsAg ≥ 9000 IU/mL (OR = 4.472, 95% CI: 3.410-5.866, p < 0.001), cirrhosis (OR = 1.650, 95% CI: 1.234-2.207, P = 0.001), LSM ≥ 13.0 kPa (OR = 1.644, 95% CI: 1.203-2.246, p = 0.002), and PLT < 100×109/L (OR = 1.450, 95% CI: 1.094-1.922, p = 0.010) at baseline were related to the development of LLV.

Conclusions

High HBV DNA/HBsAg quantification/LSM, low PLT, HBeAg positivity, and liver cirrhosis were high-risk factors associated with LLV in patients receiving entecavir treatment.

Latest insights into the epidemiology, characteristics, and therapeutic strategies of chronic hepatitis B patients in indeterminate phase

As a hepatotropic virus, hepatitis B virus (HBV) can establish a persistent chronic infection in the liver, termed, chronic hepatitis B (CHB), which causes a series of liver-related complications, including fibrosis, cirrhosis, and hepatocellular carcinoma (HCC). HCC with HBV infection has a significantly increased morbidity and mortality, whereas it could be preventable. The current goal of antiviral therapy for HBV infection is to decrease CHB-related morbidity and mortality, and achieve sustained suppression of virus replication, which is known as a functional or immunological cure. The natural history of chronic HBV infection includes four immune phases: the immune-tolerant phase, immune-active phase, inactive phase, and reactivation phase. However, many CHB patients do not fit into any of these defined phases and are regarded as indeterminate. A large proportion of indeterminate patients are only treated with dynamic monitoring rather than recommended antiviral therapy, mainly due to the lack of definite guidelines. However, many of these patients may gradually have significant liver histopathological changes during disease progression. Recent studies have focused on the prevalence, progression, and carcinogenicity of indeterminate CHB, and more attention has been given to the prevention, detection, and treatment for these patients. Herein, we discuss the latest understanding of the epidemiology, clinical characteristics, and therapeutic strategies of indeterminate CHB, to provide avenues for the management of these patients.

Development of benzimidazole-based compounds as novel capsid assembly modulators for the treatment of HBV infection

Hepatitis B virus (HBV) capsid assembly modulators (CAMs) represent a promising therapeutic approach for the treatment of HBV infection. In this study, the hit compound CDI (IC50 = 2.46 ± 0.33 μM) was identified by screening of an in-house compound library. And then novel potent benzimidazole derivatives were designed and synthesized as core assembly modulators, and their antiviral effects were evaluated in vitro and in vivo biological experiments. The results indicated that compound 26f displayed the most optimized modulator of HBV capsid assembly (IC50 = 0.51 ± 0.20 μM, EC50 = 2.24 ± 0.43 μM, CC50 = 84.29 μM) and high selectivity index. Moreover, treatment with compound 26f for 14 days significantly decreased serum levels of HBV DNA levels in the Hydrodynamic-Injection (HDI) mouse model. Therefore, compound 26f could be considered as a promising candidate drug for further development of novel HBV CAMs with the desired potency and safety.

Biophysics-Guided Lead Discovery of HBV Capsid Assembly Modifiers

Hepatitis B virus (HBV) is the leading cause of chronic liver pathologies worldwide. HBV nucleocapsid, a key structural component, is formed through the self-assembly of the capsid protein units. Therefore, interfering with the self-assembly process is a promising approach for the development of novel antiviral agents. Applied to HBV, this approach has led to several classes of capsid assembly modulators (CAMs). Here, we report structurally novel CAMs with moderate activity and low toxicity, discovered through a biophysics-guided approach combining docking, molecular dynamics simulations, and a series of assays with a particular emphasis on biophysical experiments. Several of the identified compounds induce the formation of aberrant capsids and inhibit HBV DNA replication in vitro, suggesting that they possess modest capsid assembly modulation effects. The synergistic computational and experimental approaches provided key insights that facilitated the identification of compounds with promising activities. The discovery of preclinical CAMs presents opportunities for subsequent optimization efforts, thereby opening new avenues for HBV inhibition.

Quantitative Measurement of Serum HBcrAg Can Be Used to Assess the Feasibility of Safe Discontinuation of Antiviral Therapy for Chronic Hepatitis B

Hepatitis B virus (HBV) infection is a serious global health problem, and chronic HBV infection significantly increases the risk of liver fibrosis, cirrhosis, and even hepatocellular carcinoma in patients. Current first-line therapeutics such as nucleos(t)ide analogues and interferons are unable to completely clear cccDNA, so the vast majority of patients need to take long-term or even lifelong medication. However, long-term virological and biochemical responses can be achieved in some patients after drug withdrawal. Successfully screening these patients with drug withdrawal advantages is difficult. Hepatitis-B-core-related antigen (HBcrAg) is a new HBV serological marker that which can reflect the level and transcription activity of cccDNA in hepatocytes. Therefore, HBcrAg has potential value in guiding patients in drug withdrawal. This review summarizes previous reports on HBcrAg and evaluates the application value of HBcrAg in safe drug discontinuation.

G-quadruplexes control hepatitis B virus replication by promoting cccDNA transcription and phase separation in hepatocytes

Phase separation regulates fundamental processes in gene expression and is mediated by the local concentration of proteins and nucleic acids, as well as nucleic acid secondary structures such as G-quadruplexes (G4s). These structures play fundamental roles in both host gene expression and in viral replication due to their peculiar localisation in regulatory sequences. Hepatitis B virus (HBV) covalently closed circular DNA (cccDNA) is an episomal minichromosome whose persistence is at the basis of chronic infection. Identifying the mechanisms controlling its transcriptional activity is indispensable to develop new therapeutic strategies against chronic hepatitis B. The aim of this study was to determine whether G4s are formed in cccDNA and regulate viral replication. Combining biochemistry and functional studies, we demonstrate that cccDNA indeed contains ten G4s structures. Furthermore, mutations disrupting two G4s located in the enhancer I HBV regulatory region altered cccDNA transcription and viral replication. Finally, we showed for the first time that cccDNA undergoes phase separation in a G4-dependent manner to promote its transcription in infected hepatocytes. Altogether, our data give new insight in the transcriptional regulation of the HBV minichromosome that might pave the way for the identification of novel targets to destabilize or silence cccDNA.

Thinking outside the chromosome: epigenetic mechanisms in non-canonical chromatin species

Here we investigate the role of epigenetics in the formation, transcription regulation, maintenance and termination of several non-canonical chromatin structures. Using two examples, we demonstrate how studying non-canonical structures may reveal underlying mechanisms with implications for disease and propose intriguing epigenetic avenues for further exploration.

Gene-Editing and RNA Interference in Treating Hepatitis B: A Review

The hepatitis B virus (HBV) continues to cause substantial health and economic burdens, and its target of elimination may not be reached in 2030 without further efforts in diagnostics, non-pharmaceutical prevention measures, vaccination, and treatment. Current therapeutic options in chronic HBV, based on interferons and/or nucleos(t)ide analogs, suppress the virus replication but do not eliminate the pathogen and suffer from several constraints. This paper reviews the progress on biotechnological approaches in functional and definitive HBV treatments, including gene-editing tools, i.e., zinc-finger proteins, transcription activator-like effector nucleases, and CRISPR/Cas9, as well as therapeutics based on RNA interference. The advantages and challenges of these approaches are also discussed. Although the safety and efficacy of gene-editing tools in HBV therapies are yet to be demonstrated, they show promise for the revitalization of a much-needed advance in the field and offer viral eradication. Particular hopes are related to CRISPR/Cas9; however, therapeutics employing this system are yet to enter the clinical testing phases. In contrast, a number of candidates based on RNA interference, intending to confer a functional cure, have already been introduced to human studies. However, larger and longer trials are required to assess their efficacy and safety. Considering that prevention is always superior to treatment, it is essential to pursue global efforts in HBV vaccination.

The role of Traditional Chinese medicine in anti-HBV: background, progress, and challenges

Chronic hepatitis B (CHB) remains a major world's most serious public health issues. Despite the remarkable effect of nucleos(t)ide analogues (NAs) in inhibiting hepatitis B virus (HBV) deoxyribonucleic acid (DNA) as the first-line drug, there are several limitations still, such as poor antigen inhibition, drug resistance, low-level viremia, restricting patients' functional cure. Due to the constraints of NAs, traditional medicines, such as traditional Chinese medicine (TCM), have become more prevalently used and researched in the clinical treatment of CHB as complementary alternative therapies. As a consequence, the review focuses on the background based on HBV's life cycle as well as the NAs' limitations, progress based on direct and indirect pathway of targeting HBV of TCM, and challenges of TCM. We found TCMs play an increasingly important role in anti-HBV. In a direct antiviral way, they regulate HBV infection, replication, assembly, and other aspects of the HBV life cycle. As for indirect way, TCMs can exert anti-HBV effects through targeting the host, including immune regulation, apoptosis, autophagy, oxidative stress, etc. Especially, TCMs have the advantages of strong antigenic inhibition compared to NAs. Specifically, we can combine the benefits of TCMs in strong HBV antigen inhibition with the benefits of NAs in targeted antiviral effects, in order to find a suitable combination of "TCM + NAs" to contribute to Chinese knowledge of the realisation of the "global elimination of HBV by 2030" goal of the World Health Organization.

Serum HBV RNA levels among untreated adults with chronic hepatitis B in distinct immune phases and liver histopathology statuses

HBV RNA is a novel serum biomarker that reflects intrahepatic HBV covalently closed circular DNA (cccDNA) transcription activity. Serum HBV RNA levels among treatment-naïve adults during the natural history of chronic hepatitis B (CHB) and distinct liver histopathology statuses remain elusive. In our study, we include a total of 411 treatment-naïve CHB patients, among which 43 patients were HBeAg-positive immune-tolerant [IT(e+)], 84 patients were HBeAg-positive immune active [IA(e+)], 65 patients in HBeAg-negative immune active phases [IA(e-)], 149 patients were HBeAg-negative inactive phases [IC(e-)], and 70 patients were in Gray Zone (GZ). HBV RNA was measured in this cohort and its potential correlation with traditional serological markers and liver histopathology were analyzed. Our data showed that HBV RNA was strongly correlated with HBV DNA, HBeAg, HBsAg and ALT. Further subgroup analysis revealed a close correlation between HBV RNA and HBV DNA in patients in the IA (e+) and IA (e-) phases, but neither in IT(e+) nor IC(e-) phase. HBV RNA levels were consistently increased with the advanced degrees of hepatic inflammation, but not hepatic fibrosis. Of note, HBV RNA from HBeAg-positive patients negatively correlated with liver fibrosis, whereas HBV RNA from HBeAg-negative patients was weakly associated with liver inflammation. To sum up, serum HBV RNA shows a distinct profile among CHB patients in different immune statuses and hepatic histopathology stages/grades. Simultaneous testing of HBV RNA and traditional indicators might provide a comprehensive clinical assessment of CHB patients.

Hepatitis B Virus Modulated Transcriptional Regulatory Map of Hepatic Cellular MicroRNAs

Hepatitis B virus (HBV) is an enveloped, hepatotropic, noncytopathic virus with a partially double-stranded DNA genome. It infects hepatocytes and is associated with progression to liver fibrosis and cirrhosis, culminating in hepatocellular carcinoma (HCC), accounting for 55% of total HCC cases. MicroRNAs (miRNAs) regulated by HBV play an important role in these pathologies. Mapping the miRNAs responsive to HBV and HBV-specific proteins, including HBV X protein (HBx) that harbor the majority of HBV-human protein interactions, could aid accelerate the diagnostics and therapeutics innovation against the infection and associated diseases. With this in mind, we used a unique annotation strategy whereby we first amassed 362 mature HBV responsive-human Differentially Expressed miRNAs (HBV-hDEmiRs). The core experimentally-validated messenger RNA targets of the HBV-hDEmiRs were mostly associated with viral infections and hepatic inflammation processes. Moreover, our annotation strategy enabled the characterization of HBx-dependent/independent HBV-hDEmiRs as a tool for evaluation of the impact of HBx as a therapeutic target. Bioinformatics analysis of the HBV-human protein-protein interactome revealed new insights into the transcriptional regulatory network of the HBV-hDEmiRs. We performed a comparative analysis of data on miRNAs gathered from HBV infected cell line studies and from tissue studies of fibrosis, cirrhosis, and HCC. Accordingly, we propose hsa-miR-15a-5p that is downregulated by multiple HBV proteins, including HBx, as a potential biomarker of HBV infection, and its progression to HCC. In all, this study underscores (1) the complexity of miRNA regulation in response to HBV infection and its progression into other liver pathologies and (2) provides a regulatory map of HBV-hDEmiRs and the underlying mechanisms modulating their expression through a cross talk between HBV viral proteins and human transcription factors.

Current Status and Challenges in Anti-Hepatitis B Virus Agents Based on Inactivation/Inhibition or Elimination of Hepatitis B Virus Covalently Closed Circular DNA

There has been over half a century since the discovery of hepatitis B virus (HBV) to now, but approximately 300 million patients with chronic hepatitis B (CHB) still live in the world, resulting in about one million deaths every year. Although currently approved antivirals (e.g., nucleoside analogues) are effective at reducing HBV replication, they have almost no impact on the existing HBV covalently closed circular DNA (cccDNA) reservoir. HBV cccDNA is a critical obstacle to the complete elimination of the virus via antiviral therapy. The true cure of HBV infection requires the eradication of viral cccDNA from HBV-infected cells; thus, the development of new agents directly or indirectly targeting HBV cccDNA is urgently needed due to the limitations of current available drugs against HBV infection. In this regard, it is the major focus of current anti-HBV research worldwide via different mechanisms to either inactivate/inhibit (functional cure) or eliminate (complete cure) HBV cccDNA. Therefore, this review discussed and summarized recent advances and challenges in efforts to inactivate/silence or eliminate viral cccDNA using anti-HBV agents from different sources, such as small molecules (including epigenetic drugs) and polypeptides/proteins, and siRNA or gene-editing approaches targeting/attenuating HBV cccDNA via different mechanisms, as well as future directions that may be considered in efforts to truly cure chronic HBV infection. In conclusion, no breakthrough has been made yet in attenuating HBV cccDNA, although a number of candidates have advanced into the phase of clinical trials. Furthermore, the overwhelming majority of the candidates function to indirectly target HBV cccDNA. No outstanding candidate directly targets HBV cccDNA. Relatively speaking, CCC_R08 and nitazoxanide may be some of the most promising agents to clear HBV infection in small molecule compounds. Additionally, CRISPR-Cas9 systems can directly target HBV cccDNA for decay and demonstrate significant anti-HBV activity. Consequently, gene-editing approaches targeting HBV cccDNA may be one of the most promising means to achieve the core goal of anti-HBV therapeutic strategies. In short, more basic studies on HBV infection need to be carried out to overcome these challenges.

Discovery of 4,5,6,7-Tetrahydropyrazolo[1.5-a]pyrizine Derivatives as Core Protein Allosteric Modulators (CpAMs) for the Inhibition of Hepatitis B Virus

Hepatitis B Virus (HBV) core protein allosteric modulators (CpAMs) are an attractive class of potential anti-HBV therapeutic agents. Here we describe the efforts toward the discovery of a series of 4,5,6,7-tetrahydropyrazolo[1,5-a]pyrazine (THPP) compounds as HBV CpAMs that effectively inhibit a broad range of nucleos(t)ide-resistant HBV variants. The lead compound 45 demonstrated inhibition of HBV DNA viral load in a HBV AAV mouse model by oral administration.

Hepatitis B infection status among South Africans attending public health facilities over a five-year period: 2015 to 2019

Hepatitis B, a potentially life-threatening viral infection of the liver, remains a global public health concern despite the availability of effective vaccines for over three decades. The aim of our study was to provide national data on active hepatitis B infections in the public health sector of South Africa. We conducted retrospective analyses on national laboratory data over the period 2015 to 2019. We identified 176,530 cases who tested positive for HBsAg (active infection) with a test positivity rate of 9.02%. Of these active infections, 11,355 (6.43%) were found to be chronically infected. We linked 24,839 (14.07%) and 2,461 (21.67%) HBeAg positive results to all active HBV infections and identified chronic infections respectively. Clearance of HBsAg was observed in 5,569 cases, inclusive of clearance in 135 chronic cases. Active HBV infections were significantly higher in men than women over the five years (p < 0.0001). Among individuals who were vaccine-eligible as infants (0 to 19 years old), we observed 4,981 active HBV infections, including 1,131 infections under five years old, majority of which (65.78%) were under one year old. In the under five-year age group, the HBsAg population positivity rate was 0.02% and test positivity rate was 4.83%. Among all women with active HBV infections (78,935), 85.17% were of reproductive age and of these, 13.73% were HBeAg positive. Without a birth dose of the HBV vaccine, lack of routine HBsAg screening at antenatal care, and HBsAg and HBeAg prevalence among women of reproductive age, it is likely that the majority of cases under five years old were vertically infected. Optimal HBV vaccine coverage, inclusive of a birth dose, is key to eliminating horizontal and vertical transmission of HBV. Early identification of HBV chronicity through real time data analysis is fundamental in reducing the risk of liver cirrhosis and hepatocellular carcinoma.

Structure-based Design of Novel Hepatitis B Virus Capsid Assembly Modulators

Small-molecule capsid assembly modulators (CAMs) have been recently recognized as promising antiviral agents for curing chronic hepatitis B virus (HBV) infection. A target-based in silico screening study is described, aimed towards the discovery of novel HBV CAMs. Initial optimization of four weakly active screening hits was performed via focused library synthesis. Lead compound 42 and close analogues 56 and 57 exhibited in vitro potency in the sub- and micromolar range along with good physico-chemical properties and were further evaluated in molecular docking and mechanism of action studies.

The dual functions of KDM7A in HBV replication and immune microenvironment

KDM7A (lysine demethylase 7A, also known as JHDM1D) is a histone demethylase, it is mainly involved in the intracellular post-translational modifications process. Recently, it has been proved that the histone demethylase members can regulate the replication of hepatitis B virus (HBV) and the expression of key molecules in the Janus-activated kinase-signal transducer and activator of the transcription (JAK/STAT) signaling pathway by chromatin modifying mechanisms. In our study, we identify novel roles of KDM7A in HBV replication and immune microenvironment through two subjects: pathogen and host. On the one hand, KDM7A is highly expressed in HBV-infected cells and promotes HBV replication in vitro and in vivo. Moreover, KDM7A interacts with HBV covalently closed circular DNA and augments the activity of the HBV core promoter. On the other hand, KDM7A can remodel the immune microenvironment. It inhibits the expression of interferon-stimulated genes (ISGs) through the IFN-γ/JAK2/STAT1 signaling pathway in both hepatocytes and macrophages. Further study shows that KDM7A interacts with JAK2 and STAT1 and affects their methylation. In general, we demonstrate the dual functions of KDM7A in HBV replication and immune microenvironment, and then we propose a new therapeutic target for HBV infection and immunotherapy. IMPORTANCE Histone lysine demethylase KDM7A can interact with covalently closed circular DNA and promote the replication of hepatitis B virus (HBV). The IFN-γ/JAK2/STAT1 signaling pathway in macrophages and hepatocytes is also downregulated by KDM7A. This study provides new insights into the mechanism of HBV infection and the remodeling of the immune microenvironment.

A role for immune modulation in achieving functional cure for chronic hepatitis B among current changes in the landscape of new treatments

INTRODUCTION

Chronic hepatitis B (CHB) is rarely cured using available treatments. Barriers to cure are: 1) persistence of reservoirs of hepatitis B virus (HBV) replication and antigen production (HBV DNA); 2) high burden of viral antigens that promote T cell exhaustion with T cell dysfunction; 3) CHB-induced impairment of immune responses.

AREAS COVERED

We discuss options for new therapies that could address one or more of the barriers to functional cure, with particular emphasis on the potential role of immunotherapy.

EXPERT OPINION/COMMENTARY

Ideally, a sterilizing cure for CHB would translate into finite therapies that result in loss of HBV surface antigen and eradication of HBV DNA. Restoration of a functional adaptive immune response, a key facet of successful CHB treatment, remains elusive. Numerous strategies targeting the high viral DNA and antigen burden and aiming to restore the host immune responses will enter clinical development in coming years. Most patients are likely to require combinations of several drugs, personalized according to virologic and disease characteristics, patient preference, accessibility, and affordability. The management of CHB is a global health priority. Expedited drug development requires collaborations between regulatory agencies, scientists, clinicians, and within the industry to facilitate testing of the best drug combinations.

Factors associated with persistent positive in HBV DNA level in patients with chronic Hepatitis B receiving entecavir treatment

Introduction

The clinical significance of persistent positive in Hepatitis B Virus (HBV) DNA level in patients receiving antiviral therapy is not well known. We investigated factors associated with persistent viremia (PV) in patients with chronic hepatitis B (CHB) given 78-week entecavir.

Methods

A total of 394 treatment-naïve CHB patients who had undergone liver biopsy at baseline and week 78 of treatment were analyzed in this prospective multicentre study. We identified patients with PV (above the lower limit of quantification, 20 IU/ml) after 78 weeks of entecavir therapy. Stepwise, forward, multivariate regression analyses of specified baseline parameters were apllied to identify factors associated with PV. Futhermore, we assessed the incidence of hepatocellular carcinoma (HCC) in all patients using models of the risk of HCC development.

Results

Of the 394 patients, 90 (22.8%) still with PV after 78-week antiviral treatment. Factors associated significantly with PV (vs complete virological response, CVR) were HBV DNA level ≥8 log10 IU/mL (OR, 3.727; 95% CI, 1.851-7.505; P < 0.001), Anti-HBc level < 3 log10 IU/mL (OR, 2.384; 95% CI, 1.223-4.645; P=0.011), and HBeAg seropositivity (OR, 2.871; 95% CI, 1.563-5.272; P < 0.001). Patients with PV were less likely to have fibrosis progression and HCC development than those with the CVR. Of the 11 HBeAg-positive patients with HBV DNA level ≥8 log10 IU/mL and Anti-HBc level < 3 log10 IU/mL at baseline, 9 (81.8%) had persistent positivity in HBV DNA level and 0 had fibrosis progression at week 78 of treatment.

Discussion

In conclusion, HBV DNA level ≥8 log10 IU/mL, Anti-HBc level < 3 log10 IU/mL and HBeAg seropositivity at baseline contribute to PV in patients with CHB receiving 78-week antiviral treatment. In addition, the rate of fibrosis progression and the risk of HCC development in patients with PV were kept low. The complete protocol for the clinical trial has been registered at clinicaltrials.gov (NCT01962155 and NCT03568578).

A spatiotemporally controlled recombinant cccDNA mouse model for studying HBV and developing drugs against the virus

Covalently closed circular (ccc) DNA is the template for hepatitis B virus (HBV) replication. The lack of small animal models for characterizing chronic HBV infection has hampered research progress in HBV pathogenesis and drug development. Here, we generated a spatiotemporally controlled recombinant cccDNA (rcccDNA) mouse model by combining Cre/loxP-mediated DNA recombination with the liver-specific "Tet-on/Cre" system. The mouse model harbors three transgenes: a single copy of the HBV genome (integrated at the Rosa26 locus, RHBV), H11-albumin-rtTA (spatiotemporal conditional module), and (tetO)₇-Cre (tetracycline response element), and is named as RHTC mouse. By supplying the RHTC mice with doxycycline (DOX)-containing drinking water for two days, the animals generate rcccDNA in hepatocytes, and the rcccDNA supports active HBV gene expression and can maintain HBV viremia persistence for over 60 weeks. Persistent HBV gene expression induces intrahepatic inflammation, fibrosis, and dysplastic pathology, which closely mirrors the disease progression in clinical patients. Bepirovirsen, an antisense oligonucleotide (ASO) targeting all HBV RNA species, showed dose-dependent antiviral effects in the RHTC mouse model. The spatiotemporally controlled rcccDNA mouse is convenient and reliable, providing versatile small animal model for studying cccDNA-centric HBV biology as well as evaluating antiviral therapeutics.

Targeting hepatitis B virus cccDNA levels: recent progress in seeking small molecule drug candidates

Hepatitis B virus (HBV) infection is a major global health problem that puts people at high risk of death from cirrhosis and liver cancer. The presence of covalently closed circular DNA (cccDNA) in infected cells is considered to be the main obstacle to curing chronic hepatitis B. At present, the cccDNA cannot be completely eliminated by standard treatments. There is an urgent need to develop drugs or therapies that can reduce HBV cccDNA levels in infected cells. We summarize the discovery and optimization of small molecules that target cccDNA synthesis and degradation. These compounds are cccDNA synthesis inhibitors, cccDNA reducers, core protein allosteric modulators, ribonuclease H inhibitors, cccDNA transcriptional modulators, HBx inhibitors and other small molecules that reduce cccDNA levels. Teaser: HBV covalently closed circular DNA (cccDNA) can be stably maintained in infected cells for a prolonged period, and this is the fundamental reason why hepatitis B cannot be completely cured. Here, we review recent progress in the development of small molecules that can reduce cccDNA levels in infected cells.

Liver organoids as a primary human model to study HBV-mediated Hepatocellular carcinoma. A review

Hepatitis B Virus (HBV) is the prevailing cause of chronic liver disease, which progresses to Hepatocellular carcinoma (HCC) in 75% of cases. It represents a serious health concern being the fourth leading cause of cancer-related mortality worldwide. Treatments available to date fail to provide a complete cure with high chances of recurrence and related side effects. The lack of reliable, reproducible, and scalable in vitro modeling systems that could recapitulate the viral life cycle and represent virus-host interactions has hindered the development of effective treatments so far. The present review provides insights into the current in-vivo and in-vitro models used for studying HBV and their major limitations. We highlight the use of three-dimensional liver organoids as a novel and suitable platform for modeling HBV infection and HBV-mediated HCC. HBV organoids can be expanded, genetically altered, patient-derived, tested for drug discovery, and biobanked. This review also provides the general guidelines for culturing HBV organoids and highlights their several prospects for HBV drug discovery and screening.

Live Cell Imaging Reveals HBV Capsid Translocation from the Nucleus To the Cytoplasm Enabled by Cell Division

Hepatitis B virus (HBV) capsid assembly is traditionally thought to occur predominantly in the cytoplasm, where the virus gains access to the virion egress pathway. To better define sites of HBV capsid assembly, we carried out single cell imaging of HBV Core protein (Cp) subcellular trafficking over time under conditions supporting genome packaging and reverse transcription in Huh7 hepatocellular carcinoma cells. Time-course analyses including live cell imaging of fluorescently tagged Cp derivatives showed Cp to accumulate in the nucleus at early time points (~24 h), followed by a marked re-distribution to the cytoplasm at 48 to 72 h. Nucleus-associated Cp was confirmed to be capsid and/or high-order assemblages using a novel dual label immunofluorescence strategy. Nuclear-to-cytoplasmic re-localization of Cp occurred predominantly during nuclear envelope breakdown in conjunction with cell division, followed by strong cytoplasmic retention of Cp. Blocking cell division resulted in strong nuclear entrapment of high-order assemblages. A Cp mutant, Cp-V124W, predicted to exhibit enhanced assembly kinetics, also first trafficked to the nucleus to accumulate at nucleoli, consistent with the hypothesis that Cp's transit to the nucleus is a strong and constitutive process. Taken together, these results provide support for the nucleus as an early-stage site of HBV capsid assembly, and provide the first dynamic evidence of cytoplasmic retention after cell division as a mechanism underpinning capsid nucleus-to-cytoplasm relocalization. IMPORTANCE Hepatitis B virus (HBV) is an enveloped, reverse-transcribing DNA virus that is a major cause of liver disease and hepatocellular carcinoma. Subcellular trafficking events underpinning HBV capsid assembly and virion egress remain poorly characterized. Here, we developed a combination of fixed and long-term (>24 h) live cell imaging technologies to study the single cell trafficking dynamics of the HBV Core Protein (Cp). We demonstrate that Cp first accumulates in the nucleus, and forms high-order structures consistent with capsids, with the predominant route of nuclear egress being relocalization to the cytoplasm during cell division in conjunction with nuclear membrane breakdown. Single cell video microscopy demonstrated unequivocally that Cp's localization to the nucleus is constitutive. This study represents a pioneering application of live cell imaging to study HBV subcellular transport, and demonstrates links between HBV Cp and the cell cycle.

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.

Research progress on detection methods for hepatitis B virus covalently closed circular DNA

Hepatitis B virus (HBV) infection remains a serious global public health problem, and HBV covalently closed circular DNA (cccDNA) in the nucleus of infected cells cannot be eliminated by current treatments and is a major factor in the persistence and recurrence of hepatitis B. Efficient and scientific detection methods are important for clinical monitoring of cccDNA and targeted drug development. Western blotting is the gold standard for the quantitative detection of cccDNA, but it is time-consuming and complex. In recent years, new detection technologies have been continuously updated. There are new developments and breakthroughs in both next-generation polymerase chain reaction (PCR) and non-PCR methods such as in situ hybridization. Some HBV-related markers (such as hepatitis B core-related antigen) have also been shown to be closely related to cccDNA, and they can be used as surrogate markers to indirectly reflect cccDNA content. In this paper, the main detection methods of cccDNA and their improvements are reviewed, the advantages and limitations of these methods are analysed and summarized, and future development directions are proposed.

HBV and HCV Infection in Children and Adolescents

Hepatitis B (HBV) and C (HCV) infections are the major causes of chronic liver disease and are associated with significant morbidity and mortality [...].

A Semi-mechanistic Model to Characterize the Long-Term Dynamics of Hepatitis B Virus Markers During Treatment With Lamivudine and Pegylated Interferon

Antiviral treatments against hepatitis B virus (HBV) suppress viral replication but do not eradicate the virus, and need therefore to be taken lifelong to avoid relapse. Mathematical models can be useful to support the development of curative anti-HBV agents; however, they mostly focus on short-term HBV DNA data and neglect the complex host-pathogen interaction. This work aimed to characterize the effect of treatment with lamivudine and/or pegylated interferon (Peg-IFN) in 1,300 patients (hepatitis B envelope antigen (HBeAg)-positive and HBeAg-negative) treated for 1 year. A mathematical model was developed incorporating two populations of infected cells, namely I 1 , with a high transcriptional activity, that progressively evolve into I 2 , at a rate δ tr , representing cells with integrated HBV DNA that have a lower transcriptional activity. Parameters of the model were estimated in patients treated with lamivudine or Peg-IFN alone (N = 894), and the model was then validated in patients treated with lamivudine plus Peg-IFN (N = 436) to predict the virological response after a year of combination treatment. Lamivudine had a larger effect in blocking viral production than Peg-IFN (99.4-99.9% vs. 91.8-95.1%); however, Peg-IFN had a significant immunomodulatory effect, leading to an enhancement of the loss rates of I 1 (×1.7 in HBeAg-positive patients), I 2 (> ×7 irrespective of HBeAg status), and δ tr (×4.6 and ×2.0 in HBeAg-positive and HBeAg-negative patients, respectively). Using this model, we were able to describe the synergy of the different effects occurring during treatment with combination and predicted an effect of 99.99% on blocking viral production. This framework can therefore support the optimization of combination therapy with new anti-HBV agents.

Current Challenges and Future Perspectives of Diagnosis of Hepatitis B Virus

It is estimated that approximately 260 million people worldwide are infected with the hepatitis B virus (HBV), which is one of the leading causes of liver disease and liver cancer throughout the world. Compared with developed countries, low-income and middle-income countries have limited access to resources and advanced technologies that require highly specialized staff for HBV diagnosis. In spite of the heavy burden caused by hepatitis B virus, 90% of people are still undiagnosed. The World Health Organization (WHO) goal of eliminating hepatitis B by 2030 seems very difficult to achieve due to the existing diagnostic infrastructure in low-resource regions. The majority of diagnostic laboratories still use hepatitis B surface antigen (HBsAg)-based tests. WHO's elimination plan is at risk of derailment due to phases like the window period, immune control, and occult HBV infection (OBI) not being detected by standard tests. Here, in this article, we are focusing on various diagnostic platforms for the better diagnosis of HBV. The aim of the elimination of HBV can only be achieved by detecting all phases of HBV infection, which can be executed by a combined approach of using new marker assays along with advanced pretesting and testing methods.

Effects of hepatitis B virus infection and strategies for preventing mother-to-child transmission on maternal and fetal T-cell immunity

One of the most common routes of chronic hepatitis B virus (HBV) infection is mother-to-child transmission (MTCT). Approximately 6.4 million children under the age of five have chronic HBV infections worldwide. HBV DNA high level, HBeAg positivity, placental barrier failure, and immaturity of the fetal immune are the possible causes of chronic HBV infection. The passive-active immune program for children, which consists of the hepatitis B vaccine and hepatitis B immunoglobulin, and antiviral therapy for pregnant women who have a high HBV DNA load (greater than 2 × 10⁵ IU/ml), are currently two of the most important ways to prevent the transmission of HBV from mother to child. Unfortunately, some infants still have chronic HBV infections. Some studies have also found that some supplementation during pregnancy can increase cytokine levels and then affect the level of HBsAb in infants. For example, IL-4 can mediate the beneficial effect on infants' HBsAb levels when maternal folic acid supplementation. In addition, new research has indicated that HBV infection in the mother may also be linked to unfavorable outcomes such as gestational diabetes mellitus, intrahepatic cholestasis of pregnancy, and premature rupture of membranes. The changes in the immune environment during pregnancy and the hepatotropic nature of HBV may be the main reasons for the adverse maternal outcomes. It is interesting to note that after delivery, the women who had a chronic HBV infection may spontaneously achieve HBeAg seroconversion and HBsAg seroclearance. The maternal and fetal T-cell immunity in HBV infection is important because adaptive immune responses, especially virus-specific CD8 T-cell responses, are largely responsible for viral clearance and disease pathogenesis during HBV infection. Meanwhile, HBV humoral and T-cell responses are important for the durability of protection after fetal vaccination. This article reviews the literature on immunological characteristics of chronic HBV-infected patients during pregnancy and postpartum, blocking mother-to-child transmissions and related immune mechanisms, hoping to provide new insights for the prevention of HBV MTCT and antiviral intervention during pregnancy and postpartum.

The HBV web: An insight into molecular interactomes between the hepatitis B virus and its host en route to hepatocellular carcinoma

Hepatitis B virus (HBV) is a major aetiology associated with the development and progression of hepatocellular carcinoma (HCC), the most common primary liver malignancy. Over the past few decades, direct and indirect mechanisms have been identified in the pathogenesis of HBV-associated HCC which include altered signaling pathways, genome integration, mutation-induced genomic instability, chromosomal deletions and rearrangements. Intertwining of the HBV counterparts with the host cellular factors, though well established, needs to be systemized to understand the dynamics of host-HBV crosstalk and its consequences on HCC progression. Existence of a vast array of protein-protein and protein-nucleic acid interaction databases has led to the uncoiling of the compendia of genes/gene products associated with these interactions. This review covers the existing knowledge about the HBV-host interplay and brings it down under one canopy emphasizing on the HBV-host interactomics; and thereby highlights new strategies for therapeutic advancements against HBV-induced HCC.

The sound of silence: Transgene silencing in mammalian cell engineering

To elucidate principles operating in native biological systems and to develop novel biotechnologies, synthetic biology aims to build and integrate synthetic gene circuits within native transcriptional networks. The utility of synthetic gene circuits for cell engineering relies on the ability to control the expression of all constituent transgene components. Transgene silencing, defined as the loss of expression over time, persists as an obstacle for engineering primary cells and stem cells with transgenic cargos. In this review, we highlight the challenge that transgene silencing poses to the robust engineering of mammalian cells, outline potential molecular mechanisms of silencing, and present approaches for preventing transgene silencing. We conclude with a perspective identifying future research directions for improving the performance of synthetic gene circuits.

IFIT3 Is Increased in Serum from Patients with Chronic Hepatitis B Virus (HBV) Infection and Promotes the Anti-HBV Effect of Interferon Alpha via JAK-STAT2 In Vitro

Increasing evidence indicates that interferon alpha (IFN-α) therapy is an effective treatment option for a subgroup of patients with chronic hepatitis B virus (HBV) infection. It has been confirmed that interferon-induced protein with tetratricopeptide repeats 3 (IFIT3), a member of the interferon-stimulated genes (ISGs), could inhibit the replication of various viruses. However, its effect on HBV replication is unclear. The present study sought to explore the role and mechanism of IFIT3 in IFN-α antiviral activities against HBV. IFIT3 mRNA levels in the peripheral blood of 108 treatment-naive patients and 70 healthy controls were analyzed first. The effect of IFIT3 on the Janus kinase-signal transducer and activator of transcription (JAK-STAT) signaling pathway under the dual intervention of IFN-α and HBV was also explored in vitro. Treatment-naive individuals exhibited elevated levels of IFIT3 mRNA compared to the controls (P < 0.0001). Mechanistically, the knockdown of IFIT3 inhibited the phosphorylation of signal transducer and activator of transcription 2 (STAT2), whereas the overexpression of IFIT3 produced the opposite effect in vitro. Meanwhile, the overexpression of IFIT3 enhanced the expression of IFN-α-triggered ISGs, including myxovirus resistance A (MxA), 2'-5'-oligoadenylate synthetase 1 (OAS1), and double-stranded RNA-activated protein kinase (PKR), while a weaker induction of IFN-α-triggered ISGs was observed in ruxolitinib-treated cells. After decreasing IFIT3 expression by validated small hairpin RNAs (shRNAs), the levels of hepatitis B surface antigen (HBsAg), hepatitis B e antigen (HBeAg), and HBV DNA secreted by HepG2 cells transiently transfected with the pHBV1.2 plasmid were increased. Our findings suggest that IFIT3 works in a STAT2-dependent manner to promote the antiviral effect of IFN-α through the JAK-STAT pathway in HBV infection in both human hepatocytes and hepatocarcinoma cells. IMPORTANCE Our study contributes new insights into the understanding of the functions and roles of interferon-induced protein with tetratricopeptide repeats 3 (IFIT3), which is one of the interferon-stimulated genes induced by hepatitis B virus infection in human hepatocytes and hepatocarcinoma cells, and may help to identify targeted genes promoting the efficacy of interferon alpha.

Low Risk of Occult Hepatitis B Infection among Vietnamese Blood Donors

Occult hepatitis B infection (OBI) is characterized by the presence of low levels of hepatitis B virus (HBV) DNA and undetectable HBsAg in the blood. The prevalence of OBI in blood donors in Asia ranges from 0.013% (China) to 10.9% (Laos), with no data available from Vietnam so far. We aimed to investigate the prevalence of OBI among Vietnamese blood donors. A total of 623 (114 women and 509 men) HBsAg-negative blood donors were screened for anti-HBc and anti-HBs by ELISA assays. In addition, DNA from sera was isolated and nested PCR was performed for the HBV surface gene (S); a fragment of the S gene was then sequenced in positive samples. The results revealed that 39% (n = 242) of blood donors were positive for anti-HBc, and 70% (n = 434) were positive for anti-HBs, with 36% (n = 223) being positive for both anti-HBc and anti-HBs. In addition, 3% of blood donors (n = 19) were positive for anti-HBc only, and 34% (n = 211) had only anti-HBs as serological marker. A total of 27% (n = 170) were seronegative for any marker. Two of the blood donors (0.3%) were OBI-positive and sequencing revealed that HBV sequences belonged to HBV genotype B, which is the predominant genotype in Vietnam.

Killing in self-defense: proapoptotic drugs to eliminate intracellular pathogens

Intracellular infections rely on host cell survival for replication and have evolved several mechanisms to prevent infected cells from dying. Drugs that promote apoptosis, a noninflammatory form of cell death, can dysregulate these survival mechanisms to kill infected cells via a mechanism that resists the evolution of drug resistance. Two such drug classes, known as SMAC mimetics and BH3 mimetics, have shown preclinical efficacy at mediating clearance of liver-stage malaria and chronic infections such as hepatitis-B virus and Mycobacterium tuberculosis. Emerging toxicity and efficacy data have reinforced the broad applicability of these drugs and form the foundations for preclinical and clinical studies into their various usage cases.

Discovery of Novel cccDNA Reducers toward the Cure of Hepatitis B Virus Infection

Chronic hepatitis B virus (HBV) infection is a worldwide disease that causes thousands of deaths per year. Currently, there is no therapeutic that can completely cure already infected HBV patients due to the inability of humans to eliminate covalently closed circular DNA (cccDNA), which serves as the template to (re)initiate an infection even after prolonged viral suppression. Through phenotypic screening, we discovered xanthone series hits as novel HBV cccDNA reducers, and subsequent structure optimization led to the identification of a lead compound with improved antiviral activity and pharmacokinetic profiles. A representative compound 59 demonstrated good potency and oral bioavailability with no cellular toxicity. In an HBVcircle mouse model, compound 59 showed excellent efficacy in significantly reducing HBV antigens, DNA, and intrahepatic cccDNA levels.

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.

A Study on Pregenomic RNA and Factors Related to Hepatitis B Virus Infection Based on Real World

Objective

This article aims to study the influencing factors of pgRNA and its change magnitude based on the real world.

Methods

A total of 421 patients who were tested for pgRNA were selected. According to the baseline data, the subjects were divided into negative and positive groups. The Chi-square test and logistic regression were used to analyze the influencing factors of pgRNA status. Based on the follow-up data, the rank-sum test and linear regression were used to analyze the influencing factors of pgRNA change magnitude.

Results

A total of 153 (36.3%) of the 421 subjects were pgRNA-negative and 268 (63.7%) were pgRNA-positive. Logistic regression analysis showed that positive HBV DNA (OR: 40.51), positive HBeAg (OR: 66.24), tenofovir treatment (OR: 23.47), and entecavir treatment (OR: 14.90) were the independent risk factors for positive pgRNA. Univariate linear regression showed that the pgRNA change magnitude of patients treated with entecavir was higher than that of patients treated with tenofovir. Multivariate linear regression showed that age was an independent factor influencing pgRNA change magnitude.

Conclusions

The pgRNA of patients who were young, female, HBV DNA-positive, high-HBsAg, HBeAg-positive is higher than the detection line. HBV DNA and HBeAg are the independent risk factors of positive pgRNA. Different antiviral regimens and disease stages have significantly different effects on pgRNA status. There was a significant correlation between pgRNA and FIB-4, suggesting that pgRNA is related to liver fibrosis. The decrease in pgRNA was greater in young patients than in non-young patients. The decrease in pgRNA was greater in patients treated with tenofovir than in patients treated with entecavir.

Evaluation of tumoral glypican 3 mRNA level as a diagnostic and prognostic biomarker for hepatitis-b virus-associated hepatocellular carcinoma by an integrative transcriptomic meta-analysis and bioinformatics

Aim: The aim of this study is to evaluate the potential of GPC3 mRNA level as a diagnostic and prognostic biomarker for HBV-associated HCC. Materials and Methods: GPC3 mRNA expression in HBV-associated HCC tumor tissues compared to matched adjacent tissues was evaluated by integrative transcriptomic meta-analysis. The results were validated in a different patient cohort and the possible associations between GPC3 mRNA level and the clinical variables were evaluated. Results: Transcriptomic data of HBV-associated HCC tissues (n=61) and matched adjacent tissues (n=61) from four datasets (GSE19665;GSE84402;GSE121248;GSE55092) were included in the meta-analysis. GPC3 mRNA level was found to be higher in tumors than adjacent tissues (fold change=12.88; p= 0;FDR=0). The result was validated in GSE14520, (HBV-associated HCC(n)=203; matched adjacent tissue(n)=203), (log-fold-change= 4.82; adj.p=1.43E-79). It was found that GPC3 mRNA level could distinguish HCC from adjacent tissues with high specificity and sensitivity (AUC=0.9108;95%CI=0.08792-0.9424;p

Role of hepatitis B virus in development of hepatocellular carcinoma: Focus on covalently closed circular DNA

Chronic infection with hepatitis B virus (HBV) remains a major global health problem, especially in developing countries. It may lead to prolonged liver damage, fibrosis, cirrhosis, and hepatocellular carcinoma. Persistent chronic HBV infection is related to host immune response and the stability of the covalently closed circular DNA (cccDNA) in human hepatocytes. In addition to being essential for viral transcription and replication, cccDNA is also suspected to play a role in persistent HBV infections or hepatitis relapses since cccDNA is very stable in non-dividing human hepatocytes. Understanding the pathogenicity and oncogenicity of HBV components would be essential in the development of new diagnostic tools and treatment strategies. This review summarizes the role and molecular mechanisms of HBV cccDNA in hepatocyte transformation and hepatocarcinogenesis and current efforts to its detection and targeting.

SIRT2 Promotes HBV Transcription and Replication by Targeting Transcription Factor p53 to Increase the Activities of HBV Enhancers and Promoters

Chronic hepatitis B (CHB) virus infection is one of the leading causes of cirrhosis and liver cancer. Although the major drugs against CHB including nucleos(t)ide analogs and PEG-interferon can effectively control human hepatitis B virus (HBV) infection, complete cure of HBV infection is quite rare. Targeting host factors involved in the viral life cycle contributes to developing innovative therapeutic strategies to improve HBV clearance. In this study, we found that the mRNA and protein levels of SIRT2, a class III histone deacetylase, were significantly upregulated in CHB patients, and that SIRT2 protein level was positively correlated with HBV viral load, HBsAg/HBeAg levels, HBcrAg, and ALT/AST levels. Functional analysis confirmed that ectopic SIRT2 overexpression markedly increased total HBV RNAs, 3.5-kb RNA and HBV core DNA in HBV-infected HepG2-Na⁺/taurocholate cotransporting polypeptide cells and primary human hepatocytes. In contrast, SIRT2 silencing inhibited HBV transcription and replication. In addition, we found a positive correlation between SIRT2 expression and HBV RNAs synthesis as well as HBV covalently closed circular DNA transcriptional activity. A mechanistic study suggested that SIRT2 enhances the activities of HBV enhancer I/HBx promoter (EnI/Xp) and enhancer II/HBc promoter (EnII/Cp) by targeting the transcription factor p53. The levels of HBV EnI/Xp and EnII/Cp-bound p53 were modulated by SIRT2. Both the mutation of p53 binding sites in EnI/Xp and EnII/Cp as well as overexpression of p53 abolished the effect of SIRT2 on HBV transcription and replication. In conclusion, our study reveals that, in terms of host factors, a SIRT2-targeted program might be a more effective therapeutic strategy for HBV infection.

HBV covalently closed circular DNA minichromosomes in distinct epigenetic transcriptional states differ in their vulnerability to damage

BACKGROUND AND AIMS

HBV covalently closed circular DNA (cccDNA) is a major obstacle for a cure of chronic hepatitis B. Accumulating evidence suggests that epigenetic modifications regulate the transcriptional activity of cccDNA minichromosomes. However, it remains unclear how the epigenetic state of cccDNA affects its stability.

APPROACHES AND RESULTS

By using HBV infection cell models and in vitro and in vivo recombinant cccDNA (rcccDNA) and HBVcircle models, the reduction rate of HBV cccDNA and the efficacy of apolipoprotein B mRNA editing enzyme catalytic subunit 3A (APOBEC3A)-mediated and CRISPR/CRISPR-associated 9 (Cas9)-mediated cccDNA targeting were compared between cccDNAs with distinct transcriptional activities. Interferon-α treatment and hepatitis B x protein (HBx) deletion were applied as two strategies for cccDNA repression. Chromatin immunoprecipitation and micrococcal nuclease assays were performed to determine the epigenetic pattern of cccDNA. HBV cccDNA levels remained stable in nondividing hepatocytes; however, they were significantly reduced during cell division, and the reduction rate was similar between cccDNAs in transcriptionally active and transcriptionally repressed states. Strikingly, HBV rcccDNA without HBx expression exhibited a significantly longer persistence in mice. The cccDNA with low transcriptional activity exhibited an epigenetically inactive pattern and was more difficult to access by APOBEC3A and engineered CRISPR-Cas9. The epigenetic regulator activating cccDNA increased its vulnerability to APOBEC3A.

CONCLUSIONS

HBV cccDNA minichromosomes in distinct epigenetic transcriptional states showed a similar reduction rate during cell division but significantly differed in their accessibility and vulnerability to targeted nucleases and antiviral agents. Epigenetic sensitization of cccDNA makes it more susceptible to damage and may potentially contribute to an HBV cure.

Ongoing viral replication and production of infectious virus in patients with chronic hepatitis B virus suppressed below the limit of quantitation on long-term nucleos(t)ide therapy

Nucleos(t)ide analogs are standard-of-care for the treatment of chronic hepatitis B and can effectively reduce hepatitis B virus (HBV) replication but rarely leads to cure. Nucleos(t)ide analogs do not directly eliminate the viral episome, therefore treatment cessation typically leads to rapid viral rebound. While treatment is effective, HBV DNA is still detectable (although not quantifiable) in the periphery of the majority of nucleos(t)ide analog treated HBV patients, even after prolonged treatment. Addressing whether the detectable HBV DNA represents infectious virus is a key unknown and has important implications for the development of a curative treatment for HBV. The minimum HBV genome equivalents required to establish infection in human liver chimeric mice was determined by titration of HBV patient sera and the infectivity in chimeric mice of serum from patients (n = 7) suppressed to the limit of detection on nucleos(t)ide analog therapy was evaluated. A minimum of 5 HBV genome equivalents were required to establish infection in the chimeric mice, confirming this model has sufficient sensitivity to determine whether serum from virally suppressed patients contains infectious virus. Strikingly, serum from 75% (n = 3 out of 4) of nucleos(t)ide-treated HBV patients with DNA that was detectable, but below the lower limit of quantitation, also established infection in the chimeric mice. These results demonstrate that infectious virus is still present in some HBV patients on suppressive nucleos(t)ide therapy. This residual virus may support viral persistence via continuous infection and explain the ongoing risk for HBV-related complications despite long-term suppression on therapy. Thus, additional treatment intensification may facilitate HBV cure.

Follow-Up of 108 Patients with Chronic Hepatitis B Virus Infection Treated with Polyethylene Glycol-Conjugated Derivatives of Interferon-Alpha and Monitoring of Off-Treatment Virological Relapse

BACKGROUND This single center study, which enrolled 108 patients with chronic hepatitis B virus infection treated with pegylated interferon-alpha (PEG-IFN-alpha), aimed to follow up and monitor off-treatment responses, including virological relapse, and analyze predictors of long-term efficacy of the PEG-IFN-alpha regimen. MATERIAL AND METHODS In total, 108 hepatitis B e antigen (HBeAg)-positive patients with chronic hepatitis B who had completed the PEG-IFN-alpha regimen and achieved virological suppression were enrolled. The patients were followed up for 5 years to monitor off-treatment responses. Twenty-eight relevant factors, including the history of antiviral therapy and HBeAg seroconversion, were analyzed using the Cox proportional hazards regression model. RESULTS The cumulative rates of virological suppression were 75.70%, 68.68%, 65.25%, 63.91%, and 63.91% at 1, 2, 3, 4, and 5 years of the follow-up period, respectively. Compared with the rates of virological suppression, the cumulative rates of clinical suppression were 88.41%, 79.83%, 78.59%, 75.65%, and 75.65%, respectively, for the 5 years. Alanine aminotransferase (ALT) normalization at 24 weeks after off-therapy (relative risk [RR]=3.430, P=0.013) was a potential predictor for sustained virological suppression, and the history of anti-viral therapy (RR=0.164, P=0.004), quantitative value of hepatitis B virus surface antigen (HBsAg) at 48 weeks of anti-viral therapy (RR=2.697, P=0.039), and ALT normalization at 24 weeks after off-therapy (RR=5.467, P=0.004) were potential predictors for sustained clinical suppression. CONCLUSIONS Our results suggested that increased HBsAg levels at 48 weeks and normalization of ALT at 24 weeks after off-therapy might be predictive factors for long-term treatment efficacy.[color=red] [/color].

Management and Treatment of Patients with Chronic Hepatitis B: Towards Personalized Medicine

The currently available antiviral treatments (Peg-Interferon-α and Nucleos(t)ide Analogues, NA) for chronic hepatitis B (CHB) achieve a functional cure (serum HBsAg and HDV-DNA clearance) of HBV infection in a limited number of patients. Nevertheless, the continuous pharmacological suppression of viral replication by NA halts liver disease progression lowering the risk of HCC development and improving the survival. In the near future, to fully exploit the potential of old and new drugs for HBV treatment a personalized approach to the patients will be required according to an accurate definition of their virologic, immunologic and clinical profile.

The Mechanism of Action of Hepatitis B Virus Capsid Assembly Modulators Can Be Predicted from Binding to Early Assembly Intermediates

Interfering with the self-assembly of virus nucleocapsids is a promising approach for the development of novel antiviral agents. Applied to hepatitis B virus (HBV), this approach has led to several classes of capsid assembly modulators (CAMs) that target the virus by either accelerating nucleocapsid assembly or misdirecting it into noncapsid-like particles, thereby inhibiting the HBV replication cycle. Here, we have assessed the structures of early nucleocapsid assembly intermediates, bound with and without CAMs, using molecular dynamics simulations. We find that distinct conformations of the intermediates are induced depending on whether the bound CAM accelerates or misdirects assembly. Specifically, the assembly intermediates with bound misdirecting CAMs appear to be flattened relative to those with bound accelerators. Finally, the potency of CAMs within the same class was studied. We find that an increased number of contacts with the capsid protein and favorable binding energies inferred from free energy perturbation calculations are indicative of increased potency.

Imaging of Hepatitis B Virus Nucleic Acids: Current Advances and Challenges

Hepatitis B virus infections are the main reason for hepatocellular carcinoma development. Current treatment reduces the viral load but rarely leads to virus elimination. Despite its medical importance, little is known about infection dynamics on the cellular level not at least due to technical obstacles. Regardless of infections leading to extreme viral loads, which may reach 10¹⁰ virions per mL serum, hepatitis B viruses are of low abundance and productivity in individual cells. Imaging of the infections in cells is thus a particular challenge especially for cccDNA that exists only in a few copies. The review describes the significance of microscopical approaches on genome and transcript detection for understanding hepatitis B virus infections, implications for understanding treatment outcomes, and recent microscopical approaches, which have not been applied in HBV research.