Persistence of hepatitis B virus covalently closed circular DNA in hepatocytes: molecular mechanisms and clinical significance

A hepatitis B virus-free cccDNA-producing stable cell for antiviral screening

The covalently closed circular DNA (cccDNA) of the Hepatitis B virus (HBV) serves as a template for producing progeny viruses in virally infected hepatocytes. Promising cccDNA-targeting antiviral agents remain unavailable and unpredictable in the research and development pipelines, making sterile HBV elimination challenging at the current stage. The major challenge of discriminating trace amounts of cccDNA from the abundant HBV relaxed circular DNA (rcDNA), which is nearly identical to cccDNA in sequence, substantially discourages efforts to discover and directly screen cccDNA-targeting drugs. Therefore, an easy cccDNA cell culture system is required for high-throughput drug screening. In this study, we designed an HBV cccDNA self-generating stable cell culture system using a functional complementary concept and successfully generated an HBV cccDNA Gaussia luciferase reporter cell line in HepG2 and Huh7 cells. This design ensures that the Gluc signal is exclusively expressed upon cccDNA formation, allowing for the accurate and easy measurement of cccDNA levels via luminescent signals. Using this system, in conjunction with a firefly luciferase reporter to monitor cell activity, we screened 2074 drugs in the HepG2-HBV-cccDNA/Firefly cell line. Four compounds were selected for further experimentation and their anti-HBV effects were confirmed. Thus, this virus-free hepatitis B cccDNA cell culture system provides a valuable and convenient platform for the high-throughput screening of anti-HBV drugs.

AAV-based vectors for human diseases modeling in laboratory animals

The development of therapeutic drugs and vaccines requires the availability of appropriate model animals that replicate the pathogenesis of human diseases. Both native and transgenic animals can be utilized as models. The advantage of transgenic animals lies in their ability to simulate specific properties desired by researchers. However, there is often a need for the rapid production of transgenic animal models, especially in situations like a pandemic, as was evident during COVID-19. An important tool for transgenesis is the adeno-associated virus. The genome of adeno-associated virus serves as a convenient expression cassette for delivering various DNA constructs into cells, and this method has proven effective in practice. This review analyzes the features of the adeno-associated virus genome that make it an advantageous vector for transgenesis. Additionally, examples of utilizing adeno-associated viral vectors to create animal models for hereditary, oncological, and viral human diseases are provided.

The Mechanism of APOBEC3B in Hepatitis B Virus Infection and HBV Related Hepatocellular Carcinoma Progression, Therapeutic and Prognostic Potential

Hepatocellular carcinoma (HCC) is one of the most prevalent malignant tumors globally. Prominent factors include chronic hepatitis B (CHB) and chronic hepatitis C (CHC) virus infections, exposure to aflatoxin, alcohol abuse, diabetes, and obesity. The prevalence of hepatitis B (HBV) is substantial, and the significant proportion of asymptomatic carriers heightens the challenge in diagnosing and treating hepatocellular carcinoma (HCC), necessitating further and more comprehensive research. Apolipoprotein B mRNA editing catalytic polypeptide (APOBEC) family members are single-stranded DNA cytidine deaminases that can restrict viral replication. The APOBEC-related mutation pattern constitutes a primary characteristic of somatic mutations in various cancer types such as lung, breast, bladder, head and neck, cervix, and ovary. Symptoms in the early stages of HCC are often subtle and nonspecific, posing challenges in treatment and monitoring. Furthermore, this article primarily focuses on the established specific mechanism of action of the APOBEC3B (A3B) gene in the onset and progression of HBV-related HCC (HBV-HCC) through stimulating mutations in HBV, activating Interleukin-6 (IL-6) and promoting reactive oxygen species(ROS) production, while also exploring the potential for A3B to serve as a therapeutic target and prognostic indicator in HBV-HCC.

Risk factors of HBV reactivation in leukemia patients with resolved HBV infection after allogeneic hematopoietic stem cell transplantation

BACKGROUND

The hepatitis B surface antigen (HBsAg)-negative and antibody to hepatitis B core antigen (anti-HBc)-positive patients after allogeneic hematopoietic stem cell transplantation (allo-HSCT) are at risk of HBV reactivation (HBVr).

METHODS

To analyze the risk factors for HBVr, a total of 1,042 leukemia patients(≥18years of age), who underwent allo-HSCT from January 2016 to April 2022 in The First Affiliated Hospital of Soochow University, were enrolled in the study. Finally, 193 leukemia patients with resolved HBV infection were included into the study.

RESULTS

HBVr occurred in 22 patients (11.39 %), and the median time to HBVr was 24 months (with a range of 11-51months). Hepatitis flares developed in 22.73 % of patients with HBVr, and hepatic failure occurred in 1 patient. During the follow-up period, only 1(1.3 %) patient experienced HBVr among 79 patients with antiviral prophylaxis. While 21(18.42 %) patients experienced HBVr among 114 patients without antiviral prophylaxis. The cumulative incidence of HBV reactivation at 3 years was 44.4. % for anti-HBs-negative donors/recipients with a low anti-HBs titer (<100IU/L) and 7.1 % for anti-HBs-positive donors/recipients with a high anti-HBs titer (≥100IU/L) respectively. In addition, univariate and multivariate Cox regression analyses confirmed the use of rituximab as a risk factor for HBV reactivation.

CONCLUSION

The univariate and multivariate analyses confirmed that the anti-HBs titer in both recipients and donors are protective indicators to prevent incidence of HBVr. In addition, antiviral prophylaxis can significantly reduce the incidence of HBVr.

Tenofovir versus entecavir on the prognosis of hepatitis B virus-related hepatocellular carcinoma: a reconstructed individual patient data meta-analysis

Background: Hepatitis B, often leading to Hepatocellular carcinoma (HCC), poses a major global health challenge. While Tenofovir (TDF) and Entecavir (ETV) are potent treatments, their comparative effectiveness in improving recurrence-free survival (RFS) and overall survival (OS) rates in HBV-related HCC is not well-established. Methods: We conducted an individual patient data meta-analysis using survival data from randomized trials and high-quality propensity score-matched studies to compare the impact of Tenofovir (TDF) and Entecavir (ETV) on RFS and OS in HBV-related HCC patients. Data from six databases and gray literature up to 30 August 2023, were analyzed, utilizing Kaplan-Meier curves, stratified Cox models, and shared frailty models for survival rate assessment and to address between-study heterogeneity. The study employed restricted mean survival time analysis to evaluate differences in RFS and OS between TDF-treated and ETV-treated patients. Additionally, landmark analyses compared early (<2 years) and late (≥2 years) tumor recurrence in these cohorts. Results: This study incorporated seven research articles, covering 4,602 patients with HBV-related HCC (2,082 on TDF and 2,520 on ETV). Within the overall cohort, TDF recipients demonstrated significantly higher RFS (p = 0.042) and OS (p < 0.001) than those on ETV. The stratified Cox model revealed significantly improved OS for the TDF group compared to the ETV group (hazard ratio, 0.756; 95% confidence interval, 0.639-0.896; p = 0.001), a result corroborated by the shared frailty model. Over a follow-up period of 1-8 years, no significant difference was noted in the mean time to death between the TDF and ETV groups. The rates of early recurrence did not significantly differ between the groups (p = 0.735). However, TDF treatment was significantly associated with a reduced risk of late recurrence compared to ETV (p < 0.001). In the HCC resection subgroup, the disparities in OS, early, and late recurrence rates between the two treatments paralleled those seen in the overall cohort. Conclusion: Compared to ETV, TDF may enhance OS and reduce late tumor recurrence risk in HBV-related HCC patients receiving curative treatment. However, there was no statistically significant distinction in the timing of tumor recurrence and mortality between patients administered TDF and those prescribed ETV. Systematic Review Registration: http://www.crd.york.ac.uk/prospero/.

Two Concepts of Hepatitis B Core-Related Antigen Assay: A Highly Sensitive and Rapid Assay or an Effective Tool for Widespread Screening

Hepatitis B core-related antigen (HBcrAg) reflects the activity of intrahepatic covalently closed circular DNA. HBcrAg can be detected even in chronic hepatitis B patients in whom serum HBV DNA or hepatitis B surface antigen is undetectable. The HBcrAg measurement system was developed based on two concepts. One is a fully-automated and highly-sensitive HBcrAg assay (iTACT-HBcrAg) and the other is a point-of-care testing (POCT) that can be used in in resource-limited areas. iTACT-HBcrAg is an alternative to HBV DNA for monitoring HBV reactivation and predicting the development of hepatocellular carcinoma. This validated biomarker is available in routine clinical practice in Japan. Currently, international guidelines for the prevention of mother-to-child transmission recommend anti-HBV prophylaxis for pregnant women with high viral loads. However, over 95% of HBV-infected individuals live in countries where HBV DNA quantification is widely unavailable. Given this situation, a rapid and simple HBcrAg assay for POCT would be highly effective. Long-term anti-HBV therapy may have potential side effects and appropriate treatment should be provided to eligible patients. Therefore, a simple method of determining the indication for anti-HBV treatment would be ideal. This review provides up-to-date information regarding the clinical value of HBcrAg in HBV management, based on iTACT-HBcrAg or POCT.

Arsenic trioxide impacts hepatitis B virus core nuclear localization and efficiently interferes with HBV infection

The key to a curative treatment of hepatitis B virus (HBV) infection is the eradication of the intranuclear episomal covalently closed circular DNA (cccDNA), the stable persistence reservoir of HBV. Currently, established therapies can only limit HBV replication but fail to tackle the cccDNA. Thus, novel therapeutic approaches toward curative treatment are urgently needed. Recent publications indicated a strong association between the HBV core protein SUMOylation and the association with promyelocytic leukemia nuclear bodies (PML-NBs) on relaxed circular DNA to cccDNA conversion. We propose that interference with the cellular SUMOylation system and PML-NB integrity using arsenic trioxide provides a useful tool in the treatment of HBV infection. Our study showed a significant reduction in HBV-infected cells, core protein levels, HBV mRNA, and total DNA. Additionally, a reduction, albeit to a limited extent, of HBV cccDNA could be observed. Furthermore, this interference was also applied for the treatment of an established HBV infection, characterized by a stably present nuclear pool of cccDNA. Arsenic trioxide (ATO) treatment not only changed the amount of expressed HBV core protein but also induced a distinct relocalization to an extranuclear phenotype during infection. Moreover, ATO treatment resulted in the redistribution of transfected HBV core protein away from PML-NBs, a phenotype similar to that previously observed with SUMOylation-deficient HBV core. Taken together, these findings revealed the inhibition of HBV replication by ATO treatment during several steps of the viral replication cycle, including viral entry into the nucleus as well as cccDNA formation and maintenance. We propose ATO as a novel prospective treatment option for further pre-clinical and clinical studies against HBV infection.

IMPORTANCE

The main challenge for the achievement of a functional cure for hepatitis B virus (HBV) is the covalently closed circular DNA (cccDNA), the highly stable persistence reservoir of HBV, which is maintained by further rounds of infection with newly generated progeny viruses or by intracellular recycling of mature nucleocapsids. Eradication of the cccDNA is considered to be the holy grail for HBV curative treatment; however, current therapeutic approaches fail to directly tackle this HBV persistence reservoir. The molecular effect of arsenic trioxide (ATO) on HBV infection, protein expression, and cccDNA formation and maintenance, however, has not been characterized and understood until now. In this study, we reveal ATO treatment as a novel and innovative therapeutic approach against HBV infections, repressing viral gene expression and replication as well as the stable cccDNA pool at low micromolar concentrations by affecting the cellular function of promyelocytic leukemia nuclear bodies.

STINGing Defenses: Unmasking the Mechanisms of DNA Oncovirus-Mediated Immune Escape

DNA oncoviruses represent an intriguing subject due to their involvement in oncogenesis. These viruses have evolved mechanisms to manipulate the host immune response, facilitating their persistence and actively contributing to carcinogenic processes. This paper describes the complex interactions between DNA oncoviruses and the innate immune system, with a particular emphasis on the cGAS-STING pathway. Exploring these interactions highlights that DNA oncoviruses strategically target and subvert this pathway, exploiting its vulnerabilities for their own survival and proliferation within the host. Understanding these interactions lays the foundation for identifying potential therapeutic interventions. Herein, we sought to contribute to the ongoing efforts in advancing our understanding of the innate immune system in oncoviral pathogenesis.

Advances in discovery of novel investigational agents for functional cure of chronic hepatitis B: A comprehensive review of phases II and III therapeutic agents

Chronic hepatitis B virus (HBV) infection affects over 295 million people globally and an estimated 1.6 million people in the United States. It is associated with significant morbidity and mortality due to cirrhosis, liver failure, and liver cancer. Antiviral therapy with oral nucleos(t)ide analogues is associated with high rates of virologic suppression, which in turn has been associated with a decreased risk of liver complications. However, current antiviral regimens are limited by concerns with adverse effects, adherence, resistance, long-term treatment, and ongoing risk for liver events. Novel investigational agents are currently in development and are targeted at achieving functional cure with sustained hepatitis B surface antigen (HBsAg) loss and suppression of HBV DNA. Herein we review key evidence from phases II and III trials defining the efficacy and safety profiles for key investigational agents for functional cure of chronic hepatitis B, including core/capsid inhibitors, entry inhibitors, RNA interference (siRNA/ASO), HBsAg inhibitors, Toll-like receptor agonists, checkpoint inhibitors, and therapeutic vaccines.

Novel Approaches to Inhibition of HBsAg Expression from cccDNA and Chromosomal Integrants: A Review

Hepatitis B virus (HBV) is a widely prevalent liver infection that can cause acute or chronic hepatitis. Although current treatment modalities are highly effective in the suppression of viral levels, they cannot eliminate the virus or achieve definitive cure. This is a consequence of the complex nature of HBV-host interactions. Major challenges to achieving sustained viral suppression include the presence of a high viral burden from the HBV DNA and hepatitis B surface antigen (HBsAg), the presence of reservoirs for HBV replication and antigen production, and the HBV-impaired innate and adaptive immune response of the host. Those therapeutic methods include cell entry inhibitors, HBsAg inhibitors, gene editing approaches, immune-targeting therapies and direct inhibitors of covalently closed circular DNA (cccDNA). Novel approaches that target these key mechanisms are now being studied in preclinical and clinical phases. In this review article, we provide a comprehensive review on mechanisms by which HBV escapes elimination from current treatments, and highlight new agents to achieve a definitive HBV cure.

HBV pregenome RNA as a predictor of spontanous HBeAg seroconversion in HBeAg-positive chronic hepatitis B patients

BACKGROUND

Previous studies have indicated that HBV pregenome RNA (HBV pgRNA) could predict HBeAg seroconversion among the chronic hapatitis B (CHB) patients treated with pegylated interferon (Peg-IFN) or nucleos(t)ide analogues (NAs). However, the data about the prediction of HBV pgRNA for spontaneous HBeAg seroconversion is limited.

METHODS

One hundred thirteen CHB patients with HBeAg-positive in the immune active phase were followed up for 76 weeks without antiviral treatment. Based on the laboratory test results of liver function, HBeAg, anti-HBe, and HBV DNA at week 76, patients were assigned to two groups: spontaneous HBeAg seroconversion (group A, n = 18) and non-spontaneous HBeAg seroconversion group. Among the latter group, 36 patients were selected as controls (group B, n = 36).

RESULTS

At week 12, between group A and group B, there was a significant difference in the level of HBV pgRNA (group A 6.35 ± 1.24 log10 copies/ml and group B 7.52 ± 0.79 log10 copies/ml, P = 0.001), and the difference enlarged at week 28. The receiver operating characteristic curves (AUROCs) of the HBV pgRNA level and the ∆HBV pgRNA at week 28 were 0.912 (P = 0.001, 95% CI: 0.830-0.994), and 0.934 (P = 0.001, 95% CI: 0.872-0.996), respectively. The optimal cutoffs of HBV pgRNA and the reduction from baseline (∆HBV pgRNA) at week 28 for spontaneous HBeAg seroconversion prediction were 5.63 log10 copies/ml and 1.85 log10 copies/ml, respectively. The positive predictive value and negative predictive value of HBV pgRNA and ∆HBV pgRNA at week 28 were 86.7% and 87.2%, 87.5% and 89.5%, respectively. And the combination of the HBV pgRNA level and the HBV pgRNA decreased could provide better prediction.

CONCLUSIONS

HBV pgRNA is a sound predictor for spontaneous HBeAg seroconversion among the CHB patients in immune active phase. Dynamic monitoring of HBV pgRNA is helpful for clinical treatment decision.

cccDNA-Targeted Drug Screen Reveals a Class of Antihistamines as Suppressors of HBV Genome Levels

Chronic infection with hepatitis B virus (HBV) is incurable, as the current therapeutics cannot eliminate its persistent genomic material, cccDNA. Screening systems for cccDNA-targeting therapeutics are unavailable, as low copies of cccDNA in vitro complicate detection. To address this, cccDNA copies were massively increased to levels detectable via automated plate readers. This was achieved via continuous infection in a contact-free co-culture of an HBV generator (clone F881), which stably produced clinically relevant amounts of HBV, and HBV acceptors selected to carry high cccDNA loads. cccDNA-targeted therapeutics were then identified via reduced cccDNA-specific fluorescence, taking differences in the cell numbers and viability into account. Amongst the drugs tested, the H1 antihistamine Bilastine, HBVCP inhibitors and, surprisingly, current HBV therapeutics downregulated the cccDNA significantly, reflecting the assay's accuracy and sensitivity in identifying drugs that induce subtle changes in cccDNA levels, which take years to manifest in vivo. Bilastine was the only therapeutic that did not reduce HBV production from F881, indicating it to be a novel direct suppressor of cccDNA levels. When further assessed, only the structurally similar antihistamines Pitolisant and Nizatidine suppressed cccDNA levels when other H1 antihistamines could not. Taken together, our rapid fluorescence cccDNA-targeted drug screen successfully identified a class of molecules with the potential to treat hepatitis B.

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.

Rapamycin inhibits hepatitis B virus covalently closed circular DNA transcription by enhancing the ubiquitination of HBx

Hepatitis B virus (HBV) infection is still a serious public health problem worldwide. Antiviral therapies such as interferon and nucleos(t)ide analogs efficiently control HBV replication, but they cannot eradicate chronic hepatitis B (CHB) because of their incapacity to eliminate endocellular covalently closed circular DNA (cccDNA). Thus, there is a necessity to develop new strategies for targeting cccDNA. As cccDNA is difficult to clear, transcriptional silencing of cccDNA is a possible effective strategy. HBx plays a vitally important role in maintaining the transcriptional activity of cccDNA and it could be a target for blocking the transcription of cccDNA. To screen new drugs that may contribute to antiviral therapy, the ability of 2,000 small-molecule compounds to inhibit HBx was examined by the HiBiT lytic detection system. We found that the macrolide compound rapamycin, which is clinically used to prevent acute rejection after organ transplantation, could significantly reduce HBx protein expression. Mechanistic studies demonstrated that rapamycin decreased the stability of the HBx protein by promoting its degradation via the ubiquitin-proteasome system. Moreover, rapamycin inhibited HBV RNA, HBV DNA, and cccDNA transcription levels in HBV-infected cells. In addition, HBx deficiency abrogated the inhibition of cccDNA transcription induced by rapamycin. Similar results were also confirmed in a recombinant cccDNA mouse model. In summary, we report a new small-molecule, rapamycin, which targets HBx to block HBV cccDNA transcription and inhibit HBV replication. This approach can identify new strategies to cure CHB.

Drug Discovery Study Aimed at a Functional Cure for HBV

Hepatitis B virus (HBV) causes acute and, most importantly, chronic hepatitis B worldwide. Antiviral treatments have been developed to reduce viral loads but few patients with chronic hepatitis B (CHB) achieve a functional cure. The development of new therapeutic agents is desirable. Recently, many novel agents have been developed, including drugs targeting HBV-DNA and HBV-RNA. This review provides an overview of the developmental status of these drugs, especially direct acting antiviral agents (DAAs). Serological biomarkers of HBV infection are essential for predicting the clinical course of CHB. It is also important to determine the amount and activity of covalently closed circular DNA (cccDNA) in the nuclei of infected hepatocytes. Hepatitis B core-associated antigen (HBcrAg) is a new HBV marker that has an important role in reflecting cccDNA in CHB, because it is associated with hepatic cccDNA, as well as serum HBV DNA. The highly sensitive HBcrAg (iTACT-HBcrAg) assay could be a very sensitive HBV activation marker and an alternative to HBV DNA testing for monitoring reactivation. Many of the drugs currently in clinical trials have shown efficacy in reducing hepatitis B surface antigen (HBsAg) levels. Combination therapies with DAAs and boost immune response are also under development; finding the best combinations will be important for therapeutic development.

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

Guanine nucleotide exchange factor DOCK11-binding peptide fused with a single chain antibody inhibits Hepatitis B Virus infection and replication

Hepatitis B virus (HBV) infection is a major global health problem with no established cure. Dedicator of cytokinesis 11 (DOCK11), known as a guanine nucleotide exchange factor (GEF) for Cdc42, is reported to be essential for the maintenance of HBV. However, potential therapeutic strategies targeting DOCK11 have not yet been explored. We have previously developed an in vitro virus method as a more efficient tool for the analysis of proteomics and evolutionary protein engineering. In this study, using the in vitro virus method, we screened and identified a novel antiasialoglycoprotein receptor (ASGR) antibody, ASGR3-10M, and a DOCK11-binding peptide, DCS8-42A, for potential use in HBV infection. We further constructed a fusion protein (10M-D42AN) consisting of ASGR3-10M, DCS8-42A, a fusogenic peptide, and a nuclear localization signal to deliver the peptide inside hepatocytes. We show using immunofluorescence staining that 10M-D42AN was endocytosed into early endosomes and released into the cytoplasm and nucleus. Since DCS8-42A shares homology with activated cdc42-associated kinase 1 (Ack1), which promotes EGFR endocytosis required for HBV infection, we also found that 10M-D42AN inhibited endocytosis of EGFR and Ack1. Furthermore, we show 10M-D42AN suppressed the function of DOCK11 in the host DNA repair system required for covalently closed circular DNA synthesis and suppressed HBV proliferation in mice. In conclusion, this study realizes a novel hepatocyte-specific drug delivery system using an anti-ASGR antibody, a fusogenic peptide, and DOCK11-binding peptide to provide a novel treatment for HBV.

Serum HBV DNA plus RNA reflecting cccDNA level before and during NAs treatment in HBeAg positive CHB patients

Background & Aims: Correlations between serum viral markers and intrahepatic cccDNA in patients undergoing long-term nucleos(t)ide analogues (NAs) treatment haven't been fully explored. In this study, we evaluate the correlation between intrahepatic cccDNA and other serum viral markers and intrahepatic HBV DNA in HBeAg positive chronic hepatitis B (CHB) patients during 60-month treatment with NAs. Methods: Fifty-four HBeAg positive CHB patients received long-term NAs treatment were included in this study. Serial serum samples were regularly collected and quantitatively analyzed for HBsAg, HBV DNA, HBV RNA and HBcrAg. Histological samples from liver biopsy at baseline and month 60 were analyzed for intrahepatic HBV DNA and cccDNA. Results: At baseline, serum HBV DNA plus RNA was positively associated with intrahepatic cccDNA in multivariate regression analysis (β=0.205, P<0.001). In the correlation analysis between cccDNA and serum viral markers, HBV DNA plus RNA had the highest correlation coefficient (r=0.698, P<0.001), followed by serum HBV DNA (r=0.641, P<0.001), HBV RNA (r=0.590, P<0.001), and HBcrAg (r=0.564, P<0.001). At month 60, correlations between these serum viral markers and cccDNA were not observed (P>0.05). Multivariate regression analysis showed that only the decreased HBV DNA plus RNA was positively associated with cccDNA decline (β=0.172, P =0.006). Changes of HBV DNA plus RNA (r=0.525, P=0.001) was better correlated with cccDNA decline as compared to HBV RNA (r=0.384, P=0.008), HBV DNA (r=0.431, P=0.003), and HBsAg (r=0.342, P=0.029). Conclusions: Serum HBV DNA plus RNA better correlated with intrahepatic cccDNA than other viral makers before and during NAs treatment in HBeAg positive CHB patients.

The Course of Anti-HBc Antibodies over Time in Immunocompromised Hosts

Hepatitis B virus infection results in the appearance of anti-HBc antibodies that normally persist lifelong. We analyzed the course of anti-HBc antibodies overtime, focusing on patients with a permanent loss or fluctuating anti-HBc antibodies. From 120,531 patients tested for anti-HBc antibodies (Architect, Abbott) from January 2006 to December 2020, ≥4 serial values were available in 8098 and permanent or intermittent anti-HBc loss was observed in 139 patients. It was relatively frequent in baseline anti-HBc positive, immunocompromised patients with available serial measurements of anti-HBc overtime (13% of hematologic/oncologic patients, 10% of solid organ transplant recipients, and 6% of HIV patients compared to 3% in patients with other diseases). In the same period, 12,607 samples were tested for HBsAg, anti-HBc antibodies, and HBV DNA—in nine cases we detected HBV DNA with undetectable anti-HBc and HBsAg. In four out of nine cases contamination of the PCR during processing was the likeliest cause, in another four, no further data were available, while in one the HBV DNA was later followed by a temporary anti-HBc seroconversion. In conclusion, permanent or intermittent anti-HBc loss is more common in immunocompromised hosts than in patients with other underlying diseases. Furthermore, anti-HBc and HBsAg assays can be safely used to exclude an active HBV infection, even in immunocompromised hosts.

Recent Progress and Future Prospective in HBV Cure by CRISPR/Cas

Hepatitis B virus (HBV) infection remains an important issue of global public health. Although current antiviral therapy has dramatically reduced the mortality and morbidity of chronic hepatitis B (CHB), it fails to cure it. Rebound viremia often occurs after stopping antiviral therapy. Persistent HBV covalently closed circular DNA (cccDNA) and integrated DNA under antiviral therapy form the major barrier to eradication of HBV infection. CRISPR-mediated genome editing has emerged as a promising therapeutic approach to specifically destroy persistent HBV genomes, both cccDNA and integrated DNA, for HBV cure. However, the cleavage of integrated HBV DNA by CRISPR-Cas9 will cause double-strand break (DSB) of host genome, raising a serious safety concern about genome instability and carcinogenesis. The newly developed CRISPR-derived base editors (BEs), which fuse a catalytically disabled nuclease with a nucleobase deaminase enzyme, can be used to permanently inactivate HBV genome by introducing irreversible point mutations for generation of premature stop codons without DSBs of host genome. Although promising, CRISPR-mediated base editing still faces daunting challenges before its clinical application, including the base-editing efficacy, the off-target effect, the difficulty in finding conserved target HBV sequences, and in vivo delivery efficiency. Several strategies have been adopted to optimize the efficiency and specificity of CRISPR-BEs and to improve in vivo delivery efficacy through novel viral and non-viral delivery approaches. Particularly, the non-viral delivery of Cas9 mRNA and ribonucleoprotein by lipid nanoparticles exhibits attractive potential for liver-targeted delivery in clinical. Along with all progress above, the CRISPR-mediated gene therapy will ultimately achieve HBV cure.

Hepatitis B seroconversion revisited: new insights into the natural history of acute hepatitis B virus (HBV) infection from quantitative and highly sensitive assays and novel biomarkers

BACKGROUND

Hepatitis B virus (HBV) serum markers during typical acute self-limited infection are usually depicted as a composite of traditional HBV markers. The current study updates and expands our knowledge of acute hepatitis B with quantitative molecular and serological data on longitudinal samples from five plasmapheresis donors with acute HBV.

METHODS

137 longitudinal samples from five plasmapheresis donors with acute HBV were tested, four with self-limited infection and one who developed persistent infection. Testing included quantitative hepatitis B surface antigen (HBsAg), antibodies to HBV antigens, quantitative HBV e antigen (HBeAg), HBV DNA, quantitative HBV core-related antigen (HBcrAg), the highly sensitive ARCHITECT HBsAg NEXT (HBsAgNx) assay, and a quantitative research assay for HBV pregenomic RNA (pg RNA).

RESULTS

Peak levels of HBV DNA and HBsAg differed by several orders of magnitude among the panels (2.2 × 105-2.7 × 109 IU/ml for HBV DNA and 7.9-1.1 × 105 IU/ml for HBsAg). HBsAg levels peaked an average of 2.8 days after the HBV DNA peak. The overall duration of observed HBsAg positivity was increased by the more sensitive HBsAgNx assay compared to the quantitative assay in four panels. Intermittently detectable low-level HBV DNA was observed after HBsAg loss in three panels. Peak HBeAg levels occurred 2-20 days after the DNA peak and ranged from 1.1 to 4.5 × 103 IU/ml. In four panels with resolution of infection, anti-HBs levels indicating immunity (≥ 10 mIU/ml) were detected 19-317 days after the HBV DNA peak. Maximum HBcrAg concentrations ranged from 1 × 105 to > 6.4 × 106 U/ml and correlated with HBeAg values (R2 = 0.9495) and with HBV DNA values (R2 = 0.8828). Peak pgRNA values ranged from 1.6 × 103 to 1.4 × 108 U/ml and correlated with HBV DNA (R2 = 0.9013).

CONCLUSION

Traditional and new/novel HBV biomarkers were used to generate molecular and serological profiles for seroconversion panels spanning the early to late phases of acute HBV. Seroconversion profiles were heterogeneous and may be instructive in appreciating the spectrum of acute profiles relative to the typical composite representation.

Serum hepatitis B core-related antigen as a surrogate marker of hepatitis B e antigen seroconversion in chronic hepatitis B

BACKGROUND

Quantitative hepatitis B core-related antigen (qHBcrAg) has a better correlation with intrahepatic hepatitis B virus (HBV) covalently closed circular DNA (cccDNA) than HBV DNA or hepatitis B e antigen (HBeAg), but data are still lacking for its clinical application.

AIM

The aim was to investigate serum qHBcrAg levels in patients with chronic hepatitis B and assess the correlation of serum qHBcrAg with pregenomic RNA (pgRNA), cccDNA, and HBeAg seroconversion.

METHODS

This study was a secondary analysis of patients who underwent percutaneous liver biopsy between July 2014 and June 2019 in two multicenter randomized controlled clinical trials of peginterferon vs nucleos(t)ide analog (NUC)-based therapy (NCT03509688 and NCT03546530). Serum qHBcrAg, pgRNA, HBV DNA, hepatitis B core antigen, HBeAg, liver cccDNA, and HBV DNA were measured. The correlations of serum qHBcrAg with other biomarkers were analyzed.

RESULTS

A total of 139 patients were included. The mean qHBcrAg levels were 5.32 ± 1.18 log₁₀ U/mL at baseline and decreased during treatment (all P < 0.0001). Serum qHBcrAg levels were positively correlated with pgRNA (r = 0.597, P < 0.0001) and cccDNA (r = 0.527, P < 0.0001) levels. The correlation of serum qHBcrAg level and intrahepatic HBV DNA levels at baseline was weak but significant (r = 0.399, P < 0.0001). HBcrAg predicted HBeAg seroconversion, with areas under the receiver operating characteristics curve of 0.788 at 24 wk and 0.825 at 48 wk. Log HBcrAg at wk 24 and 48 was independently associated with HBeAg seroconversion [odds ratio (OR) = 2.402, 95% confidence interval (CI): 1.314-4.391, P = 0.004; OR = 3.587, 95%CI: 1.315-9.784, P = 0.013].

CONCLUSION

Serum HBcrAg levels were correlated with HBV virological markers and could be used to predict HBeAg seroconversion.

The Application of the CRISPR/Cas9 System in the Treatment of Hepatitis B Liver Cancer

The clustered regularly interspaced short palindromic repeats (CRISPR)/CRISPR-associated protein 9 (Cas9) system was originally discovered in prokaryotes and functions as part of the adaptive immune system. The experimental research of many scholars, as well as scientific and technological advancements, has allowed prokaryote-derived CRISPR/Cas genome-editing systems to transform our ability to manipulate, detect, image, and annotate specific DNA and RNA sequences in the living cells of diverse species. Through modern genetic engineering editing technology and high-throughput gene sequencing, we can edit and splice covalently closed circular DNA to silence it, and correct the mutation and deletion of liver cancer genes to achieve precise in situ repair of defective genes and prohibit viral infection or replication. Such manipulations do not destroy the structure of the entire genome and facilitate the cure of diseases. In this review, we discussed the possibility that CRISPR/Cas could be used as a treatment for patients with liver cancer caused by hepatitis B virus infection, and reviewed the challenges incurred by this effective gene-editing technology.

Hepatitis B Core-Related Antigen and New Therapies for Hepatitis B

The hepatitis B core-related antigen (HBcrAg) is an unprecedented novel HBV biomarker that plays an essential role in reflecting covalently closed circular DNA (cccDNA) in chronic hepatitis B (CHB) because its levels correlate with intrahepatic cccDNA and serum HBV DNA. In this review, we describe the clinical application of serum HBcrAg in CHB patients, with a particular focus on new therapies targeting intrahepatic HBV replication. (1) HBcrAg can be detected in clinical cases where serum HBV DNA is undetectable during anti-HBV therapy. (2) A highly sensitive HBcrAg assay (iTACT-HBcrAg) may be useful for monitoring HBV reactivation, as an alternative to HBV DNA. (3) Decreased HBcrAg levels have been significantly associated with promising outcomes in CHB patients, reducing the risk of progression or recurrence of hepatocellular carcinoma. Additionally, we focus on and discuss several drugs in development that target HBV replication, and monitoring HBcrAg may be useful for determining the therapeutic efficacies of such novel drugs. In conclusion, HBcrAg, especially when measured by the recently developed iTACT-HBcrAg assay, may be the most appropriate surrogate marker, over other HBV biomarkers, to predict disease progression and treatment response in CHB patients.

Advances in therapeutic application of CRISPR-Cas9

Clustered regularly interspaced short palindromic repeats (CRISPR)-associated protein 9 (Cas9) is one of the most versatile and efficient gene editing technologies, which is derived from adaptive immune strategies for bacteria and archaea. With the remarkable development of programmable nuclease-based genome engineering these years, CRISPR-Cas9 system has developed quickly in recent 5 years and has been widely applied in countless areas, including genome editing, gene function investigation and gene therapy both in vitro and in vivo. In this paper, we briefly introduce the mechanisms of CRISPR-Cas9 tool in genome editing. More importantly, we review the recent therapeutic application of CRISPR-Cas9 in various diseases, including hematologic diseases, infectious diseases and malignant tumor. Finally, we discuss the current challenges and consider thoughtfully what advances are required in order to further develop the therapeutic application of CRISPR-Cas9 in the future.

Distribution and factors associated with serum HBV pregenomic RNA levels in Chinese chronic hepatitis B patients

Correlations between serum hepatitus B virus (HBV) pregenomic RNA (pgRNA), hepatitus B surface antigen (HBsAg), and hepatitus B core-related antigen (HBcrAg) levels, and influencing factors of serum HBV pgRNA levels in Chinese chronic hepatitis B (CHB) patients are rarely reported. This was a retrospective cohort study consisting of 204 outpatients with CHB. Serum levels of HBV pgRNA, HBsAg, and HBcrAg were quantitative measured in frozen blood samples. The linear regression and multivariate logistic regression analysis were performed to determine associated factors of serum HBV pgRNA levels. In this cohort, the median serum HBV pgRNA level was 4.12 log10 copies/ml and 33.33% (68/204) of them had serum HBV pgRNA under low limit of detection (LLD) (<500 copies/ml); and the percentage of patients with serum HBV pgRNA under LLD in hepatitis B e antigen (HBeAg)-positive patients was significantly lower than that in HBeAg-negative patients (15.75% [23/46] vs. 77.59% [45/58], p < .001). Overall, serum HBV pgRNA strongly correlated with HBcrAg (r = 0.760, p < .001), and moderately correlated with HBV DNA (r = 0.663, p < .001) and HBsAg (r = 0.670, p < .001). As compared with HBsAg and HBV DNA, only HBcrAg showed stable correlation with serum HBV pgRNA both in HBeAg-positive and HBeAg-negative patients. Serum HBV pgRNA level differed between HBeAg-positive and HBeAg-negative patients; and it had better and more stable correlation with serum HBcrAg than serum HBV DNA and HBsAg, irrespective of HBeAg status.

MicroRNA‑1271‑5p alleviates the malignant development of hepatitis B virus‑mediated liver cancer via binding to AQP5

Hepatitis B virus (HBV) is a leading cause of liver-related cancer. Progress has been made on the study of microRNA (miRNA or miR) function in HBV-related liver cancer. Hence, the objective of the present study was to determine the role and functional mechanism of miR-1271-5p in HBV-associated liver cancer. miR-1271-5p and aquaporin 5 (AQP5) expression at the mRNA level were measured by reverse transcription-quantitative PCR (RT-qPCR). The levels of hepatitis B e-antigen (HBeAg), hepatitis B surface antigen (HBsAg) and HBV DNA were assessed by ELISA or qPCR. Cell viability, apoptosis, migration and invasion were detected by Cell Counting Kit-8, flow cytometry or Transwell assay. The interaction of miR-1271-5p and AQP5 was predicted by TargetScan, and verified by Dual-luciferase reporter assay and RNA binding protein immunoprecipitation assay. The protein levels of AQP5, Bax, Bcl-2, cleaved-caspase-3 and proliferating cell nuclear antigen were quantified by western blot analysis. Nude mouse tumorigenicity assay was conducted to examine the role of miR-1271-5p in vivo. miR-1271-5p was downregulated, while AQP5 was upregulated in HBV-related liver cancer cells and tissues. Overexpression of miR-1271-5p or AQP5 knockdown inhibited the levels of HBeAg, HBsAg and HBV DNA, blocked cell viability, migration and invasion, and induced apoptosis. AQP5 was confirmed to be a direct target of miR-1271-5p, and miR-1271-5p exerted its role through targeting AQP5. Overexpression of miR-1271-5p impeded tumor growth in vivo by weakening the expression of AQP5. In conclusion, miR-1271-5p blocked the progression of HBV-induced liver cancer by competitively targeting AQP5.

Tenofovir Disoproxil Fumarate Is Superior to Entecavir in Reducing Hepatitis B Surface Antigen for Chronic Hepatitis B in China: 2-Year Comprehensive Comparative Result of a Matched Comparative Study

Aim: Tenofovir disoproxil fumarate (TDF) and entecavir (ETV) are equally recommended as the first-line antiviral treatments for chronic hepatitis B (CHB) at present. We aimed to compare the long-term efficacy and safety between ETV and TDF therapy in CHB patients who had not received nucleoside analog treatment.

Method: In this single-center retrospective study, 414 patients who received ETV (290 patients) or TDF (124 patients) therapy at our center from January 2017 to May 2019 were included. To reduce the imbalance of baseline variables, propensity score matching (PSM) was employed to yield 124 pairs of patients at a ratio of 1:1 based on the treatment regimen.

Result: After PSM, the cumulative rate of patients who achieved complete virological response (CVR) was not different by drug therapy at each inspection time (1, 3, 6, 12, 18, and 24 months). Subgroup analysis on HBeAg status and level of HBV DNA demonstrated that evolution of proportion of achieving CVR was not significantly different between groups. Despite the insignificant incidence of HBsAg seroclearance in either group, patients in TDF group achieved higher on-treatment HBsAg decline at each inspection time (1, 3, 6, 9, 12, 18, and 24 months), 0.39, 0.51, 0.61, 0.64, 0.68, 0.76, and 0.91 log IU/mL, respectively; while the corresponding reduction were 0.27, 0.37, 0.40, 0.45, 0.48, 0.55, and 0.66 log IU/mL in ETV group (p < 0.05). In subgroup analysis, we found that the significant difference still existed in patients with high baseline HBsAg level (>3 log IU/mL). Additionally, the proportion of patients who achieved on-treatment HBsAg decline >1 log IU/mL in TDF and ETV group was 33.3 and 17.1% (p < 0.01) at the 12th month, 44.4 and 29.5% (p = 0.03) at the 24th month, respectively. Mean increase in serum creatinine from baseline was 0.10 and 0.08 mg/dL in TDF and ETV group (p = 0.11), with no patient experienced acute kidney injury.

Conclusions: TDF has higher potency in reducing HBsAg than ETV in this study. Considering the effect still existed in patients with high HBsAg level (>3 log IU/mL), TDF might be a superior therapeutic regimen combining with its relatively safety.

DOCK11 and DENND2A play pivotal roles in the maintenance of hepatitis B virus in host cells

Human hepatitis B virus (HBV) infection remains a serious health problem worldwide. However, the mechanism for the maintenance of HBV in a latent state within host cells remains unclear. Here, using single-cell RNA sequencing analysis, we identified four genes linked to the maintenance of HBV in a liver cell line expressing HBV RNA at a low frequency. These genes included DOCK11 and DENND2A, which encode small GTPase regulators. In primary human hepatocytes infected with HBV, knockdown of these two genes decreased the amount of both HBV DNA and covalently closed circular DNA to below the limit of detection. Our findings reveal a role for DOCK11 and DENND2A in the maintenance of HBV.

Hepatitis B Virus Reactivation in Gastrointestinal Stromal Tumor Patients Treated With Imatinib

Purpose

Hepatitis B virus reactivation (HBVr) in patients with gastrointestinal stromal tumors (GISTs) have not been sufficiently characterized. This study aimed to review the possible mechanism of HBVr induced by imatinib and explore appropriate measures for patient management and monitoring.

Methods

The clinical data of GIST patients who experienced HBVr due to treatment with imatinib at Xiangya Hospital (Changsha, Hunan, China) were retrospectively analyzed. A literature review was also conducted.

Results

Five cases were analyzed, including 3 cases in this study. The average age of the patients was 61.8 y, with male preponderance (4 of 5 vs. 1 of 5). These patients received imatinib as adjuvant treatment (n=4) or as neoadjuvant treatment (n=1). Primary tumors were mostly located in the stomach (n=4) or rectum (n=1). High (n=3) or intermediate (n=1) recurrence risk was categorized using the postoperative pathological results (n=4). Imatinib was then started at 400 (n=4) or 200 mg (n=1) daily. Patients first reported abnormal liver function during the 2^th (n=1),6^th (n=3), or 10^th (n=1) month of treatment with imatinib. Some patients (n=4) discontinued imatinib following HBVr; notably, 1 month after discontinuation, 1 patient experienced HBVr. Antivirals (entecavir n=4, tenofovir n=1), artificial extracorporeal liver support (n=1), and liver transplant (n=1) were effective approaches to treating HBVr. Most patients (n=3) showed favorable progress, 1 patient underwent treatment, and 1 patient died due to severe liver failure induced by HBVr.

Conclusions

Although HBVr is a rare complication (6.12%), HBV screening should be conducted before starting treatment with imatinib in GIST patients. Prophylactic therapy for hepatitis B surface antigen positive patients, prompt antiviral treatment and cessation of imatinib are also necessary.

Identification and characterization of a G-quadruplex structure in the pre-core promoter region of hepatitis B virus covalently closed circular DNA

Approximately 250 million people worldwide are chronically infected with the hepatitis B virus (HBV) and are at increased risk of developing cirrhosis and hepatocellular carcinoma. The HBV genome persists as covalently closed circular DNA (cccDNA), which serves as the template for all HBV mRNA transcripts. Current nucleos(t)ide analogs used to treat HBV do not directly target the HBV cccDNA genome and thus cannot eradicate HBV infection. Here, we report the discovery of a unique G-quadruplex structure in the pre-core promoter region of the HBV genome that is conserved among nearly all genotypes. This region is central to critical steps in the viral life cycle, including the generation of pregenomic RNA, synthesis of core and polymerase proteins, and genome encapsidation; thus, an increased understanding of the HBV pre-core region may lead to the identification of novel anti-HBV cccDNA targets. We utilized biophysical methods (circular dichroism and small-angle X-ray scattering) to characterize the HBV G-quadruplex and the effect of three distinct G to A mutants. We also used microscale thermophoresis to quantify the binding affinity of G-quadruplex and its mutants with a known quadruplex-binding protein (DHX36). To investigate the physiological relevance of HBV G-quadruplex, we employed assays using DHX36 to pull-down cccDNA and compared HBV infection in HepG2 cells transfected with wild-type and mutant HBV plasmids by monitoring the levels of genomic DNA, pregenomic RNA, and antigens. Further evaluation of this critical host-protein interaction site in the HBV cccDNA genome may facilitate the development of novel anti-HBV therapeutics against the resilient cccDNA template.

PD-L1 is induced on the hepatocyte surface via CKLF-like MARVEL transmembrane domain-containing protein 6 up-regulation by the anti-HBV drug Entecavir

Chronic hepatitis B is now controllable when treated with nucleoside reverse transcriptase inhibitors (NRTIs), which inhibit hepatitis B virus (HBV) replication. However, once the NRTIs are discontinued, most patients relapse, necessitating lifelong NRTIs treatment. HBV infection relapse is assumed to be caused by the persistent existence of covalently closed circular DNA (cccDNA) in the nuclei of infected hepatocytes. The mechanism by which cccDNA-positive hepatocytes escape immune surveillance during NRTIs treatment remains elusive. Entecavir (ETV), a commonly used NRTI, post-transcriptionally up-regulates programmed cell death-ligand 1 (PD-L1), an immune checkpoint molecule, on the cell surface of hepatocytes regardless of HBV infection. Up-regulation by ETV depends on up-regulation of CKLF-like MARVEL transmembrane domain-containing 6, a newly identified potent regulator of PD-L1 expression on the cell surface. ETV-treated hepatic cells suppressed the activity of primary CD3 T cells and programmed cell death protein-1 (PD-1)-over-expressed Jurkat cells. Finally, ETV induces PD-L1 in primary hepatocytes infected by HBV. These results provide evidence that ETV considerably up-regulates PD-L1 on the cell surface of infected hepatocytes, which may be one of the mechanisms by which infected hepatocytes subvert immune surveillance.

Hepatitis B reactivation: diagnosis and management

INTRODUCTION

Hepatitis B virus (HBV) reactivation can be induced by treatments that attenuate the immunological control over HBV, leading to increased morbidity and mortality. The risk of HBV reactivation is determined by host immunity, viral factors, and the type and dose of treatments. Nevertheless, the risk of HBV reactivation for a growing number of novel therapies remains uncertain and needs to be carefully examined. Identification of patients at risk and administration of prophylactic antiviral agents are critical to prevent HBV reactivation. Early diagnosis and initiation of antiviral treatment are the keys to avoid devastating outcomes.

AREA COVERED

We summarized the latest evidence and recommendations for risk stratification, early diagnosis, prophylaxis, and management of HBV reactivation.

EXPERT OPINION

Universal screening, adequate prophylaxis, and close monitoring are essential for the prevention of HBV reactivation. Risk stratification of patients at risk with appropriate antiviral prophylaxis can prevent HBV reactivation effectively. Several emerging biomarkers have been proved to help determine the risk precisely. Early detection and timely administration of antiviral agents are crucial for management. Further studies on the precision of risk stratification as well as the optimal duration of prophylaxis and treatment are needed to establish an individualized strategy.

The Interactions between HBV and the Innate Immunity of Hepatocytes

Hepatitis B virus (HBV) infection affects ~350 million people and poses a major public health problem worldwide. HBV is a major cause of cirrhosis and hepatocellular carcinoma. Fewer than 5% of HBV-infected adults (but up to 90% of HBV-infected infants and children) develop chronic HBV infection as indicated by continued, detectable expression of hepatitis B surface antigen (HBsAg) for at least 6 months after the initial infection. Increasing evidence indicates that HBV interacts with innate immunity signaling pathways of hepatocytes to suppress innate immunity. However, it is still not clear how HBV avoids monitoring by the innate immunity of hepatocytes and whether the innate immunity of hepatocytes can be effective against HBV if re-triggered. Moreover, a deep understanding of virus-host interactions is important in developing new therapeutic strategies for the treatment of HBV infection. In this review, we summarize the current knowledge regarding how HBV represses innate immune recognition, as well as recent progress with respect to in vitro models for studying HBV infection and innate immunity.

Safety, pharmacokinetics, and antiviral effects of ABI-H0731, a hepatitis B virus core inhibitor: a randomised, placebo-controlled phase 1 trial

BACKGROUND

Therapies with novel mechanisms of action against hepatitis B virus (HBV) infection are being explored with the goal of achieving a functional cure (sustained off-treatment response) without requiring lifelong therapy. We aimed to evaluate the pharmacokinetics, safety, and antiviral activity of ABI-H0731, an investigational inhibitor of the HBV core protein.

METHODS

This phase 1, randomised, placebo-controlled study was done in two parts. In part 1, healthy adults without hepatitis B aged 18-65 years at one clinical research centre in New Zealand (eight participants per dose cohort) were randomly assigned (3:1) to receive single oral doses of ABI-H0731 (100, 300, 600, or 1000 mg) or matching placebo, or once-daily or twice-daily doses of ABI-H0731 800 mg or matching placebo for 7 days. In part 2, adults aged 18-65 years at clinical research centres in New Zealand, Australia, the UK, Hong Kong, Taiwan, and South Korea with chronic HBV (12 participants per dose cohort) were randomly assigned (5:1) to receive ABI-H0731 (100, 200, 300, or 400 mg) or matching placebo once daily for 28 days. In part 2, participants were required to have HBeAg-positive or HBeAg-negative chronic HBV infection, with serum HBV DNA concentrations of at least 2 × 104 IU/mL (HBeAg-positive) or 2 × 103 IU/mL (HBeAg-negative) and serum alanine aminotransferase concentrations less than seven times the upper limit of normal. Both parts used simple randomisation, with study participants, site personnel, and study monitors masked to treatment assignments. The primary study objective was dose-related safety and tolerability of ABI-H0731 in healthy volunteers and in participants with chronic HBV infection, assessed in all treated participants. Key secondary assessments included pharmacokinetic analyses and virological responses. This study is registered with ClinicalTrials.gov, identifier NCT02908191 and is completed.

FINDINGS

48 [61%] of 79 healthy volunteers were enrolled in the single-ascending or multiple-ascending dose phase of part 1 between Nov 16, 2016, and Jan, 27, 2017. 38 [55%] of 69 HBV-infected participants were enrolled in part 2 between June 15, 2017, and March 15, 2018. All adverse events were non-specific and of mild or moderate intensity apart from a single HBV-infected participant given the 400 mg dose who developed a severe (grade 3) maculopapular rash and terminated treatment. Overall, the most frequent adverse events of any grade among the 74 participants who received ABI-H0731 were headache (11 [15%]), influenza-like illness (seven [9%]), and dizziness (six [8%]); the most frequent adverse events considered treatment-related were rash (four [5%]) and dizziness (three [4%]). In part 1, ABI-H0731 reached maximum plasma concentrations (Tmax) in 2·50-4·17 h; the mean plasma half-life (t1/2) was 23·5-28·4 h. In part 2, mean maximum HBV DNA declines from baseline were 1·7 log10 IU/mL in the 100 mg dose cohort, 2·1 log10 IU/mL in the 200 mg dose cohort, and 2·8 log10 IU/mL in the 300 mg dose cohort. Across dose cohorts, serum HBV RNA declines correlated with HBV DNA declines.

INTERPRETATION

No pattern of treatment-emergent adverse events was observed at ABI-H0731 doses up to 300 mg in individuals with chronic hepatitis B. ABI-H0731 was rapidly absorbed and exhibited a plasma half-life supportive of once-daily dosing. Dose-dependent decreases in serum HBV DNA and RNA concentrations are consistent with the proposed mechanism of action.

FUNDING

Assembly Biosciences.

Novel Biomarkers of Hepatitis B and Hepatocellular Carcinoma: Clinical Significance of HBcrAg and M2BPGi

The hepatitis B virus (HBV) cannot be removed completely from infected hepatocytes, owing to the presence of intrahepatic covalently closed circular DNA (cccDNA). As chronic hepatitis B (CHB) can progress to cirrhosis and hepatocellular carcinoma (HCC), predicting HCC development in high-risk patients with high viral replicative activity or advanced fibrosis is important. Novel serological biomarkers reflect intrahepatic viral replicative activity or the progression of liver fibrosis, indicating non-invasive alternatives to liver biopsy: (1) Hepatitis B core-related antigen (HBcrAg) correlates with serum HBV DNA and intrahepatic cccDNA. In CHB patients, a decrease in HBcrAg is associated with favorable outcomes. HBcrAg can predict HCC occurrence or recurrence. (2) Measurement of the Mac-2 binding protein glycosylation isomer (M2BPGi) has been introduced for the evaluation of liver fibrosis. An increase in M2BPGi in CHB patients is related to the progression of liver fibrosis and high potential (risk) of HCC development. Here, we describe the clinical applications of HBcrAg and M2BPGi in CHB patients. Additionally, because new potential therapeutic agents that eliminate intrahepatic cccDNA are being developed, monitoring of HBcrAg or M2BPGi might be suitable for evaluating therapeutic effects and the clinical outcomes. In conclusion, these would be appropriate surrogate markers for predicting disease progression.

Novel Biomarkers of Hepatitis B and Hepatocellular Carcinoma: Clinical Significance of HBcrAg and M2BPGi

The hepatitis B virus (HBV) cannot be removed completely from infected hepatocytes, owing to the presence of intrahepatic covalently closed circular DNA (cccDNA). As chronic hepatitis B (CHB) can progress to cirrhosis and hepatocellular carcinoma (HCC), predicting HCC development in high-risk patients with high viral replicative activity or advanced fibrosis is important. Novel serological biomarkers reflect intrahepatic viral replicative activity or the progression of liver fibrosis, indicating non-invasive alternatives to liver biopsy: (1) Hepatitis B core-related antigen (HBcrAg) correlates with serum HBV DNA and intrahepatic cccDNA. In CHB patients, a decrease in HBcrAg is associated with favorable outcomes. HBcrAg can predict HCC occurrence or recurrence. (2) Measurement of the Mac-2 binding protein glycosylation isomer (M2BPGi) has been introduced for the evaluation of liver fibrosis. An increase in M2BPGi in CHB patients is related to the progression of liver fibrosis and high potential (risk) of HCC development. Here, we describe the clinical applications of HBcrAg and M2BPGi in CHB patients. Additionally, because new potential therapeutic agents that eliminate intrahepatic cccDNA are being developed, monitoring of HBcrAg or M2BPGi might be suitable for evaluating therapeutic effects and the clinical outcomes. In conclusion, these would be appropriate surrogate markers for predicting disease progression.

Host Transcription Factors in Hepatitis B Virus RNA Synthesis

The hepatitis B virus (HBV) chronically infects over 250 million people worldwide and is one of the leading causes of liver cancer and hepatocellular carcinoma. HBV persistence is due in part to the highly stable HBV minichromosome or HBV covalently closed circular DNA (cccDNA) that resides in the nucleus. As HBV replication requires the help of host transcription factors to replicate, focusing on host protein–HBV genome interactions may reveal insights into new drug targets against cccDNA. The structural details on such complexes, however, remain poorly defined. In this review, the current literature regarding host transcription factors’ interactions with HBV cccDNA is discussed.

Replenishment of Hepatitis B Virus cccDNA Pool Is Restricted by Baseline Expression of Host Restriction Factors In Vitro

BACKGROUND

Covalently closed circular DNA (cccDNA) of hepatitis B virus (HBV) is the major cause of viral persistence in patients with chronic HBV infection. Understanding the mechanisms underlying stability and persistence of HBV cccDNA in hepatocytes is critical for developing novel therapeutics and managing chronic hepatitis B. In this study, we observed an unexpected increase in HBV cccDNA levels upon suppression of transcription by de novo DNA methyltransferase DNMT3A and uncovered additional mechanisms potentially involved in HBV cccDNA maintenance.

METHODS

HBV-expressing cell lines were transfected with a DNMT3A-expressing plasmid. Real-time PCR and HBsAg assays were used to assess the HBV replication rate. Cell cycling was analyzed by fluorescent cell sorting. CRISPR/Cas9 was utilized to abrogate expression of APOBEC3A and APOBEC3B. Alterations in the expression of target genes were measured by real-time PCR.

RESULTS

Similar to previous studies, HBV replication induced DNMT3A expression, which in turn, led to reduced HBV transcription but elevated HBV cccDNA levels (4- to 6-fold increase). Increased levels of HBV cccDNA were not related to cell cycling, as DNMT3A accelerated proliferation of infected cells and could not contribute to HBV cccDNA expansion by arresting cells in a quiescent state. At the same time, DNMT3A suppressed transcription of innate immunity factors including cytidine deaminases APOBEC3A and APOBEC3B. CRISPR/Cas9-mediated silencing of APOBEC3A and APOBEC3B transcription had minor effects on HBV transcription, but significantly increased HBV cccDNA levels, similar to DNMT3A. In an attempt to further analyze the detrimental effects of HBV and DNMT3A on infected cells, we visualized γ-H2AX foci and demonstrated that HBV inflicts and DNMT3A aggravates DNA damage, possibly by downregulating DNA damage response factors. Additionally, suppression of HBV replication by DNMT3A may be related to reduced ATM/ATR expression.

CONCLUSION

Formation and maintenance of HBV cccDNA pools may be partially suppressed by the baseline expression of host inhibitory factors including APOBEC3A and APOBEC3B. HBV inflicts DNA damage both directly and by inducing DNMT3A expression.

Prevalence of hepatocarcinoma-related hepatitis B virus mutants in patients in grey zone of treatment

BACKGROUND

Antiviral treatment of patients with chronic hepatitis B (CHB) in the grey zone of treatment comands risk management in order to optimize the health outcome. In this sense, the identification of HBV mutants related with an increased risk of hepatocellular carcinoma (HCC) could be useful to identify subpopulations with potential indication of antiviral treatment.

AIM

To analyze the prevalence/persistence of hepatitis B virus (HBV) preS and basal core promoter (BCP)/precore/core variants associated to HCC development in CHB patients in the grey zone.

METHODS

Work was designed as a longitudinal retrospective study, including 106 plasma samples from 31 patients with CHB in the grey zone of treatment: Hepatitis B e antigen negative, HBV-DNA levels between 12-20000 IU/mL, normal or discordant transaminase levels during follow up and mild/moderate necro-inflammatory activity in liver biopsy or Fibroscan (up to 9.5 kPa). Serum HBV-DNA was tested using the Abbott Real Time HBV Assay and the BCP/precore/core and the hepatitis B surface antigen (HBsAg) coding regions were analyzed in positive samples by PCR/bulk-sequencing to identify the HCC-related HBV mutants.

RESULTS

High-risk HCC related mutants were detected in 24 (77%) patients: 19 (61%) in the BCP/precore/core, and 7 (23%) in the HBsAg coding region (2 preS1 and 5 preS2 deletions). The prevalence of preS deletions was genotype-dependent: 3/5 (60%) patients with preS2 deletions and 1/2 with preS1 deletions were infected with the HBV-E genotype. Since HBV-E was the most prevalent in sub-Saharan patients, a correlation between preS deletions and ethnicity was also found: 6/8 (75%) sub-Saharan vs 1/19 (5%) Caucasian patients had preS deletions (P = 0.00016). Remarkably, this correlation was maintained in those patients infected with HBV-A, a minor genotype in sub-Saharan patients: 2/2 patients infected with HBV-A from West Africa vs 0/6 of Caucasian origin had preS deletions. The HCC related variants were the major strains and persisted over time (up to 48 mo). Patients with preS deletions had a significant higher prevalence of F2 fibrosis stage than the negatives (57% vs 10%, P = 0.0078).

CONCLUSION

HBV genetic analysis of selected populations, like sub-Saharans infected with HBV-E/A genotypes, will allow identification of subpopulations with risk of HCC development due to accumulation of high-risk HBV variants, thus commanding their increased clinical surveillance.

Durability of Hepatitis B Surface Antigen Loss With Nucleotide Analogue and Peginterferon Therapy in Patients With Chronic Hepatitis B

In patients with chronic hepatitis B (CHB), loss of hepatitis B surface antigen (HBsAg) is considered a functional cure. However, HBsAg loss is uncommon with existing therapies, and predictive factors associated with HBsAg seroreversion are unknown. Using pooled data from three phase 3 clinical trials of patients with CHB treated with nucleos(t)ide analogue (NUC) monotherapy or peginterferon (Peg‐IFN) ± NUC combination therapy, we conducted a retrospective analysis to characterize patients who achieved sustained HBsAg loss, the predictors of HBsAg seroreversion, and the impact of hepatitis B surface antibody (anti‐HBs) seroconversion on durability of HBsAg loss. In these three international trials, 1,381 adults with CHB received either NUC monotherapy for up to 10 years or Peg‐IFN‐containing regimens for up to 1 year. A total of 55 patients had confirmed HBsAg loss, defined as two or more consecutive negative‐qualitative HBsAg results, with a minimum of one repeat result after the end of treatment. Throughout a median of 96 (quartile [Q]1, Q3, 46, 135) weeks follow‐up after HBsAg loss, HBsAg loss was durable in 82% (n = 45) of patients, with 10 patients experiencing HBsAg seroreversion. Anti‐HBs seroconversion was observed during follow‐up in 78% of patients who lost HBsAg and in 60% of those who subsequently seroreverted. In analyzing predictors of HBsAg seroreversion, study treatment was significant, yet anti‐HBs seroconversion and treatment duration after initial HBsAg loss were not. Risk of HBsAg seroreversion was observed to be lower if HBsAg loss was sustained through the off‐treatment week 24 visit (8/10 seroreversions occurred by posttreatment week 24). Conclusion: HBsAg loss after NUC or Peg‐IFN‐containing regimens was durable in 82% of patients with CHB. Anti‐HBs seroconversion and treatment duration after initial HBsAg loss were not significantly associated with durability of HBsAg loss.

Drugs in the Pipeline for HBV

Chronic hepatitis B remains a significant cause of morbidity and mortality worldwide. Most hepatitis B virus (HBV)-infected individuals are neither diagnosed nor treated. In those treated, nucleos(t)ide polymerase inhibitors persistently suppress viremia to the limits of quantitation; however, few achieve a "functional cure," defined as sustained off-treatment loss of detectable serum HBV DNA with or without loss of hepatitis B surface antigen. The low cure rate has been attributed to an inability to eliminate the viral reservoir of covalently closed circular DNA from hepatocytes. This review focuses on the diverse therapeutic approaches currently under development that may contribute to the goal of HBV cure.

Biological basis for functional cure of chronic hepatitis B

Chronic hepatitis B (CHB) infection affects over 250 millon people worldwide and 800000 are expected to die yearly due to the development of hepatocellular carcinoma (HCC). Current antiviral therapies include nucleoside analogs (NAs) that target the viral retrotranscriptase inhibiting de novo viral production. Pegylated interferon (Peg-IFN) is also effective in reducing the viral DNA load in serum. However, both treatments remain limited to control the infection, aiming for viral suppression and improving the quality of life of the infected patients. Complete cure is not possible due to the presence of the stable DNA intermediate covalently closed circular DNA (cccDNA). Attempts to achieve a functional cure are thus ongoing and novel targets and molecules, together with different combination therapies are currently in the pipeline for early clinical trials. In this review we discuss novel treatments both targeting directly and indirectly cccDNA. As we gain knowledge in the Hepatitis B virus (HBV) transcriptional control, and newer technologies emerge that could potentially allow the destruction of cccDNA, exciting new possibilities for curative therapies are discussed.

MicroRNA‑20 induces methylation of hepatitis B virus covalently closed circular DNA in human hepatoma cells

Methylation was suggested to suppress the transcriptional activity of hepatitis B virus (HBV) covalently closed circular DNA (cccDNA) in hepatocytes. This may be associated with its low replicative activity during the inactive stage of chronic HBV infection; however, the exact mechanisms of methylation in HBV infection remain unknown. We have previously shown that short hairpin RNAs induced the methylation of the HBV genome in hepatoma cell lines. We also reported that the microRNA (miR) 17–92 cluster negatively regulates HBV replication in human hepatoma cells. In addition, miR-20a, a member of the miR 17–92 cluster, has sequence homology with the short hairpin RNA that induces HBV methylation. In the present study, we investigated whether miR-20a can function as an endogenous effector of HBV DNA methylation. The results indicated that overexpression of miR-20a could suppress the replicative activity of HBV and increased the degree of methylation of HBV cccDNA in the HepAD38 hepatoma cell line. Argonaute (AGO)1 and AGO2, effectors of the RNA-induced silencing complex, were detected in the nucleus of HepAD38 cells; however, only AGO2 was bound to HBV cccDNA. In addition, intranuclear AGO2 was determined to be bound with miR-20a. In conclusion, miR-20a may be loaded onto AGO2, prior to its translocation into the nucleus, inducing the methylation of HBV DNA in human hepatoma cells, leading to the suppression of HBV replication.

The Role of Hepatitis B Core-Related Antigen

Hepatitis B virus (HBV) cannot be completely eliminated from infected hepatocytes due to the existence of intrahepatic covalently closed circular DNA (cccDNA). Serological biomarkers reflect intrahepatic viral replicative activity as non-invasive alternatives to liver biopsy. Hepatitis B core-related antigen (HBcrAg) is a novel biomarker that has an important role in chronic hepatitis B (CHB), because it correlates with serum HBV DNA and intrahepatic cccDNA. In clinical cases with undetectable serum HBV DNA or loss of HBsAg, HBcrAg still can be detected and the decrease in HBcrAg levels is significantly associated with promising outcomes for CHB patients. HBcrAg can predict spontaneous or treatment-induced hepatitis B envelope antigen (HBeAg) seroconversion, persistent responses before and after cessation of nucleos(t)ide analogues, potential HBV reactivation, HBV reinfection after liver transplantation, and risk of hepatocellular carcinoma progression or recurrence. In this review, the clinical applications of HBcrAg in CHB patients based on its virological features are described. Furthermore, new potential therapeutic anti-HBV agents that affect intrahepatic cccDNA are under development, and the monitoring of HBcrAg might be useful to judge therapeutic effects. In conclusion, HBcrAg might be a suitable surrogate marker beyond other HBV markers to predict the disease progression and treatment responses of CHB patients.

Serum HBcrAg is better than HBV RNA and HBsAg in reflecting intrahepatic covalently closed circular DNA

The correlation between serum HBcrAg and HBV RNA is unclear, and correlations of intrahepatic cccDNA with HBcrAg, HBV RNA and HBsAg are rarely reported in the same cohort. This study aimed to assess the correlation of HBcrAg with HBV RNA and HBsAg, and investigate whether serum HBcrAg is superior to serum HBV RNA and HBsAg in reflecting intrahepatic HBV cccDNA in HBeAg-positive and HBeAg-negative CHB patients. In this study, 85 HBeAg-positive and 25 HBeAg-negative patients who have never received antiviral therapy were included. Among HBeAg-positive patients, HBcrAg was correlated positively with HBsAg (r = 0.564, P < 0.001) and HBV RNA (r = 0.445, P < 0.001), and HBV RNA was also correlated positively with HBsAg (r = 0.323, P = 0.003). Among HBeAg-negative patients, no significant correlation was observed between HBcrAg, HBsAg and HBV RNA. By multivariable linear regression, HBcrAg (β = -0.563, P < 0.001), HBsAg (β = -0.328, P < 0.001) and HBV RNA (β = 0.180, P = 0.003) were all associated with cccDNA levels among HBeAg-positive patients, but only serum HBcrAg was associated with cccDNA level (β = 0.774, P = 0.000) among HBeAg-negative patients. HBcrAg was better correlated with cccDNA as compared to HBsAg and HBV RNA, irrespective of HBeAg status. Among HBeAg-positive patients, though HBcrAg level was influenced by hepatic inflammatory activity and HBV DNA levels, the good correlations of HBcrAg with cccDNA persisted after stratification by inflammatory activity and HBV DNA levels. In conclusion, correlations of serum HBcrAg, HBV RNA and HBsAg levels differ significantly between HBeAg-positive and HBeAg-negative patients, but serum HbcrAg correlates with cccDNA levels better than HBV RNA and HBsAg, irrespective of HBeAg status.

Orthologous CRISPR/Cas9 systems for specific and efficient degradation of covalently closed circular DNA of hepatitis B virus

Covalently closed circular DNA (cccDNA) of hepatitis B virus (HBV) is the major cause of viral persistence and chronic hepatitis B. CRISPR/Cas9 nucleases can specifically target HBV cccDNA for decay, but off-target effects of nucleases in the human genome limit their clinical utility. CRISPR/Cas9 systems from four different species were co-expressed in cell lines with guide RNAs targeting conserved regions of the HBV genome. CRISPR/Cas9 systems from Streptococcus pyogenes (Sp) and Streptococcus thermophilus (St) targeting conserved regions of the HBV genome blocked HBV replication and, most importantly, resulted in degradation of over 90% of HBV cccDNA by 6 days post-transfection. Degradation of HBV cccDNA was impaired by inhibition of non-homologous end-joining pathway and resulted in an erroneous repair of HBV cccDNA. HBV cccDNA methylation also affected antiviral activity of CRISPR/Cas9. Single-nucleotide HBV genetic variants did not impact anti-HBV activity of St CRISPR/Cas9, suggesting its utility in targeting many HBV variants. However, two or more mismatches impaired or blocked CRISPR/Cas9 activity, indicating that host DNA will not likely be targeted. Deep sequencing revealed that Sp CRISPR/Cas9 induced off-target mutagenesis, whereas St CRISPR/Cas9 had no effect on the host genome. St CRISPR/Cas9 system represents the safest system with high anti-HBV activity.

Brca1 is involved in tolerance to adefovir dipivoxil‑induced DNA damage

Nucleos(t)ide analogues (NAs) are currently the most important anti‑viral treatment option for patients with chronic hepatitis B (CHB). Adefovir dipivoxil (ADV), a diester pro‑drug of adefovir, has been widely used for the clinical therapy of hepatitis B virus infection. It has been previously reported that adefovir induced chromosomal aberrations (CAs) in the in vitro human peripheral blood lymphocyte assay, while the genotoxic mechanism remains elusive. To evaluate the possible mechanisms, the genotoxic effects of ADV on the TK6 and DT40 cell lines, as well as DNA repair‑deficient variants of DT40 cells, were assessed in the present study. A karyotype assay revealed ADV‑induced CAs, particularly chromosomal breaks, in wild‑type DT40 and TK6 cells. A γ‑H2AX foci formation assay confirmed the presence of DNA damage following treatment with ADV. Furthermore, Brca1‑/‑ DT40 cells exhibited an increased sensitivity to ADV, while the knockdown of various other DNA damage‑associated genes did not markedly affect the sensitivity. These comprehensive genetic studies identified the genotoxic capacity of ADV and suggested that Brca1 may be involved in the tolerance of ADV‑induced DNA damage. These results may contribute to the development of novel drugs against CHB with higher therapeutic efficacy and less genotoxicity.

A global scientific strategy to cure hepatitis B

Chronic hepatitis B virus (HBV) infection is a global public health challenge on the same scale as tuberculosis, HIV, and malaria. The International Coalition to Eliminate HBV (ICE-HBV) is a coalition of experts dedicated to accelerating the discovery of a cure for chronic hepatitis B. Following extensive consultation with more than 50 scientists from across the globe, as well as key stakeholders including people affected by HBV, we have identified gaps in our current knowledge and new strategies and tools that are required to achieve HBV cure. We believe that research must focus on the discovery of interventional strategies that will permanently reduce the number of productively infected cells or permanently silence the covalently closed circular DNA in those cells, and that will stimulate HBV-specific host immune responses which mimic spontaneous resolution of HBV infection. There is also a pressing need for the establishment of repositories of standardised HBV reagents and protocols that can be accessed by all HBV researchers throughout the world. The HBV cure research agenda outlined in this position paper will contribute markedly to the goal of eliminating HBV infection worldwide.