Upregulation of HBV transcription by sodium taurocholate cotransporting polypeptide at the postentry step is inhibited by the entry inhibitor Myrcludex B

The Culprit Behind HBV-Infected Hepatocytes: NTCP

Hepatitis B virus (HBV) is a globally prevalent human DNA virus responsible for over 250 million cases of chronic liver infections, leading to conditions such as liver inflammation, cirrhosis and hepatocellular carcinoma (HCC). Sodium taurocholate co-transporting polypeptide (NTCP) is a transmembrane protein highly expressed in human hepatocytes and functions as a bile acid (BA) transporter. NTCP has been identified as the receptor that HBV and its satellite virus, hepatitis delta virus (HDV), use to enter hepatocytes. HBV entry into hepatocytes is tightly regulated by various signaling pathways, and NTCP plays an important role as the initial stage of HBV infection. NTCP acts as an initiation signal, causing metabolic changes in hepatocytes and facilitating the entry of HBV into hepatocytes. Thus, a comprehensive understanding of NTCP's role is crucial. In this review, we will examine the regulatory mechanisms governing HBV pre-S1 binding to liver membrane NTCP, the role of NTCP in HBV internalization, and the transcriptional and translational regulation of NTCP expression. Additionally, we will discuss clinical drugs targeting NTCP, including combination therapies involving NTCP inhibitors, and consider the safety of NTCP as a therapeutic target.

Gender-specific alteration of steroid metabolism and its impact on viral replication in a mouse model of hepatitis B virus infection

Hepatitis B virus (HBV) is a sex-specific pathogen that is more severe in males than in females. Sex disparities in HBV infection have been attributed to hormonal differences between males and females. However, whether HBV infection affects the metabolic signatures of steroid hormones and how these influences viral replication remains unclear. In this study, we investigated whether HBV infection alters steroid metabolism and its effects on HBV replication. Serum samples from male and female mice obtained after the hydrodynamic injection of replication-competent HBV plasmids were subjected to quantitative steroid profiling. Serum steroid levels in mice were analyzed using an in vitro metabolism assay with the mouse liver S9 fraction. The alteration of steroids by HBV infection was observed only in male mice, particularly with significant changes in androgens, whereas no significant hormonal changes were observed in female mice. Among the altered steroids, dehydroepiandrosterone (DHEA) levels increased the most in male mice after HBV infection. An in vitro metabolism assay revealed that androgen levels were significantly reduced in HBV-infected male mice. Furthermore, the genes involved in DHEA biosynthesis were significantly upregulated in HBV-infected male mice. Interestingly, reduced dihydrotestosterone in male mice significantly inhibits viral replication by suppressing HBV promoter activity, suggesting a viral strategy to overcome the antiviral effects of steroid hormones in males. Our data demonstrated that HBV infection can cause sex-specific changes in steroid metabolism.

Targeting NTCP for liver disease treatment: A promising strategy

The sodium taurocholate co-transporting polypeptide (NTCP), a bile acids transporter, has been identified as a new therapeutic target for the treatment of liver disease. This paper thoroughly investigates the function of NTCP for regulating bile acid regulation, its correlation with hepatitis B and D infections, and its association with various liver diseases. Additionally, in this review we examine recent breakthroughs in creating NTCP inhibitors and their prospective applications in liver disease treatment. While this review emphasizes the promising potential of targeting NTCP, it concurrently underscores the need for broader and more detailed research to fully understand the long-term implications and potential side effects associated with NTCP inhibition.

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.

Mitochondrial Glycerol-3-Phosphate Dehydrogenase Restricts HBV Replication via the TRIM28-Mediated Degradation of HBx

Hepatitis B virus (HBV) infection affects hepatic metabolism. Serum metabolomics studies have suggested that HBV possibly hijacks the glycerol-3-phosphate (G3P) shuttle. In this study, the two glycerol-3-phosphate dehydrogenases (GPD1 and GPD2) in the G3P shuttle were analyzed for determining their role in HBV replication and the findings revealed that GPD2 and not GPD1 inhibited HBV replication. The knockdown of GPD2 expression upregulated HBV replication, while GPD2 overexpression reduced HBV replication. Moreover, the overexpression of GPD2 significantly reduced HBV replication in hydrodynamic injection-based mouse models. Mechanistically, this inhibitory effect is related to the GPD2-mediated degradation of HBx protein by recruiting the E3 ubiquitin ligase TRIM28 and not to the alterations in G3P metabolism. In conclusion, this study revealed GPD2, a key enzyme in the G3P shuttle, as a host restriction factor in HBV replication. IMPORTANCE The glycerol-3-phosphate (G3P) shuttle is important for the delivery of cytosolic reducing equivalents into mitochondria for oxidative phosphorylation. The study analyzed two key components of the G3P shuttle and identified GPD2 as a restriction factor in HBV replication. The findings revealed a novel mechanism of GPD2-mediated inhibition of HBV replication via the recruitment of TRIM28 for degrading HBx, and the HBx-GPD2 interaction could be another potential therapeutic target for anti-HBV drug development.

Advancing beyond reverse transcriptase inhibitors: The new era of hepatitis B polymerase inhibitors

Hepatitis B virus (HBV) is a genetically diverse blood-borne virus responsible for chronic hepatitis B. The HBV polymerase plays a key role in viral genome replication within the human body and has been identified as a potential drug target for chronic hepatitis B therapeutics. However, available nucleotide reverse transcriptase inhibitors only target the reverse transcriptase domain of the HBV polymerase; they also pose resistance issues and require lifelong treatment that can burden patients financially. In this study, various chemical classes are reviewed that have been developed to target different domains of the HBV polymerase: Terminal protein, which plays a vital role in the formation of the viral DNA; Reverse transcriptase, which is responsible for the synthesis of the viral DNA from RNA, and; Ribonuclease H, which is responsible for degrading the RNA strand in the RNA-DNA duplex formed during the reverse transcription process. Host factors that interact with the HBV polymerase to achieve HBV replication are also reviewed; these host factors can be targeted by inhibitors to indirectly inhibit polymerase functionality. A detailed analysis of the scope and limitations of these inhibitors from a medicinal chemistry perspective is provided. The structure-activity relationship of these inhibitors and the factors that may affect their potency and selectivity are also examined. This analysis will be useful in supporting the further development of these inhibitors and in designing new inhibitors that can inhibit HBV replication more efficiently.

DNA Repair Factor Poly(ADP-Ribose) Polymerase 1 Is a Proviral Factor in Hepatitis B Virus Covalently Closed Circular DNA Formation

The biogenesis and eradication of HBV cccDNA have been a research priority in recent years. In this study, we identified the DNA repair factor PARP1 as a host factor required for the HBV de novo cccDNA formation.

Establishment and Characterization of a New Cell Culture System for Hepatitis B Virus Replication and Infection

Hepatitis B virus (HBV) is a primary cause of chronic liver diseases in humans. HBV infection exhibits strict host and tissue tropism. HBV core promoter (Cp) drives transcription of pregenomic RNA (pgRNA) and plays a key role in the viral life cycle. Hepatocyte nuclear factor 4α (HNF4α) acts as a major transcriptional factor that stimulates Cp. In this work, we reported that BEL7404 ​cell line displayed a high efficiency of DNA transfection and high levels of HBV antigen expression after transfection of HBV replicons without prominent viral replication. The introduction of exogenous HNF4α and human sodium taurocholate cotransporting polypeptide (hNTCP) expression into BEL7404 made it permissive for HBV replication and susceptible to HBV infection. BEL7404-derived cell lines with induced HBV permissiveness and susceptibility were constructed by stable co-transfection of hNTCP and Tet-inducible HNF4α followed by limiting dilution cloning. HBV replication in such cells was sensitive to inhibition by nucleotide analog tenofovir, while the infection was inhibited by HBV entry inhibitors. This cell culture system provides a new and additional tool for the study of HBV replication and infection as well as the characterization of antiviral agents.

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BEL7404 ​cells are characterized by a high transfection efficiency, but do not support canonical HBV replication.

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BEL7404 ​cells lack endogenous HNF4α expression, and exogenous HNF4α rescues canonical HBV replication.

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BEL7404 ​cells with stable hNTCP and inducible HNF4α expression support HBV infection and inducible replication.

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BEL7404-derived cell lines supporting HBV infection retain high transfection efficiencies and allow testing of antivirals.

Enhanced host immune responses in presence of HCV facilitate HBV clearance in coinfection

Hepatitis B virus (HBV)/Hepatitis C virus (HCV) coinfection is frequently observed because of the common infection routine. Despite the reciprocal inhibition exerted by HBV and HCV genomes, the coinfection of HBV and HCV is associated with more severe forms of liver diseases. However, the complexity of viral interference and underlying pathological mechanism is still unclarified. With the demonstration of absence of direct viral interplay, some in vitro studies suggest the indirect effects of viral-host interaction on viral dominance outcome. Here, we comprehensively investigated the viral replication and host immune responses which might mediate the interference between viruses in HBV/HCV coinfected Huh7-NTCP cells and immunocompetent HCV human receptors transgenic ICR mice. We found that presence of HCV significantly inhibited HBV replication in vitro and in vivo irrespective of the coinfection order, while HBV did not affect HCV replication. Pathological alteration was coincidently reproduced in coinfected mice. In addition to the participation of innate immune response, an involvement of HCV in up-regulating HBV-specific immune responses was described to facilitate HBV clearance. Our systems partially recapitulate HBV/HCV coinfection and unveil the uncharacterized adaptive anti-viral immune responses during coinfection, which renews the knowledge on the nature of indirect viral interaction during HBV/HCV coinfection.

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HCV inhibited HBV replication in Huh7-NTCP cells.

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HCV suppressed HBV in immunocompetent mice.

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Induced innate immune response by HCV limited HBV replication.

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Presence of HCV enhanced HBV specific immune response.

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Moderate and acute live injure was caused by HBV/HCV coinfection.

Advances in new antivirals for chronic hepatitis B

Chronic hepatitis B virus (HBV) infection remains a global health burden. Timely and effective antiviral therapy is beneficial for patients with HBV infection. With existing antiviral drugs, including nucleos(t)ide analogs and interferon-alfa, patients can achieve viral suppression with improved prognosis. However, the rate of hepatitis B surface antigen loss is low. To achieve a functional cure and even complete cure in chronic hepatitis B patients, new antivirals need to be developed. In this review, we summarized the advantages and disadvantages of existing antiviral drugs and focused on new antivirals including direct-acting antiviral drugs and immunotherapeutic approaches.

Chronic hepatitis B: New potential therapeutic drugs target

Chronic hepatitis B (CHB) infection remains the most causative agent of liver-related morbidity and mortality worldwide. It impacts nearly 300 million people. The current treatment for chronic infection with the hepatitis B virus (HBV) is complex and lacks a durable treatment response, especially hepatitis B surface antigen (HBsAg) loss, necessitating indefinite treatment in most CHB patients due to the persistence of HBV covalently closed circular DNA (cccDNA). New drugs that target distinct steps of the HBV life cycle have been investigated, which comprise inhibiting the entry of HBV into hepatocytes, disrupting or silencing HBV cccDNA, modulating nucleocapsid assembly, interfering HBV transcription, and inhibiting HBsAg release. The achievement of a functional cure or sustained HBsAg loss in CHB patients represents the following approach towards HBV eradication. This review will explore the up-to-date advances in the development of new direct-acting anti-HBV drugs. Hopefully, with the combination of the current antiviral drugs and the newly developed direct-acting antiviral drugs targeting the different steps of the HBV life cycle, the ultimate eradication of CHB infection will soon be achieved.

[Bulevirtide as the first specific agent against hepatitis D virus infections-mechanism and clinical effect]

Die Blockade des Zelleintritts von Krankheitserregern ist ein geeigneter Ansatz, um Neuinfektionen zu verhindern. Der therapeutische Einsatz von Eintrittsinhibitoren bei chronisch infizierten Patienten war jedoch bisher nur begrenzt erfolgreich. Zur Behandlung von chronischen Hepatitis-D-Virus-(HDV-)Infektionen wurde im Juli 2020 mit Bulevirtide (BLV) ein vielversprechender Wirkstoff bedingt zugelassen, der auf diesem Wirkprinzip beruht. Zuvor hatten für HDV keine gezielte Medikation zur Verfügung gestanden und die Behandlung beruhte auf dem Off-Label-Einsatz von Interferon-Alpha/Peginterferon-Alpha (IFNα/Peg-IFNα). In diesem Beitrag wird ein Überblick über die Grundlagen des Wirkmechanismus von BLV gegeben und bisher vorliegende klinische Daten werden zusammengefasst.

Eine HDV-Infektion manifestiert sich als Ko- oder Superinfektion bei Hepatitis-B-Virus-(HBV-)Infektionen und betrifft 4,5–15 % der HBV-Patienten weltweit. HDV nutzt die Hüllproteine von HBV zur Verbreitung. BLV wirkt, indem es den HBV/HDV-Rezeptor natriumtaurocholat-co-transportierendes Polypeptid (NTCP) blockiert und so den Eintritt von HBV/HDV in Hepatozyten verhindert. BLV senkt die HDV-Serum-RNA-Spiegel und führt bei HBV/HDV-infizierten Personen zur Normalisierung der Alanin-Aminotransferase-(ALT-)Werte. Es hat ein ausgezeichnetes Sicherheitsprofil, selbst wenn es über 48 Wochen in hohen Dosen (10 mg täglich) verabreicht wird. In Kombination mit Peg-IFNα zeigt BLV synergistische Effekte auf die Senkung der HDV-RNA im Serum, aber auch auf die Hepatitis-B-Oberflächenantigen-(HBsAg‑)Spiegel. Dies führte bei einer Untergruppe von Patienten zu einer funktionellen Heilung, wenn 2 mg BLV plus Peg-IFNα verabreicht wurden. Der Mechanismus dieser wahrscheinlich immunvermittelten Eliminierung wird in Folgestudien untersucht.

ADAR1 Inhibits HBV DNA Replication via Regulating miR-122-5p in Palmitic Acid Treated HepG2.2.15 Cells

BACKGROUND AND AIMS

Changes in living standards and diet structure, non-alcoholic fatty liver disease (NAFLD) is prevalent globally, including in Asia, where chronic hepatitis B (CHB) is endemic. As such, cooccurrence of NAFLD with CHB is common in Asia. However, the pathogenesis underlying the onset of fatty liver in CHB prognosis has not been fully elucidated. Therefore, we aimed to investigate the effects and mechanisms of lipotoxicity on hepatitis B virus (HBV) DNA replication.

METHODS

The expression of adenosine deaminase acting on RNA-1 (ADAR1) and miR-122 was evaluated in liver tissues from patients with CHB concurrent NAFLD. Palmitic acid-treated HepG2.2.15 cells were used as the cell model. The effect of lipotoxicity on HBV DNA replication was evaluated in vitro by transfecting the ADAR1 overexpression or knockdown lentiviral vector into HepG2.2.15 cells, respectively. qRT-PCR, western blotting and immunofluorescence were performed to determine ADAR1 expression.

RESULTS

The expression of ADAR1 in the liver tissues of CHB patients with concurrent NAFLD was significantly down-regulated compared with that in CHB patients. Enforced expression of ADAR1 inhibited the HBV DNA replication, whereas ADAR1 knockdown resulted in increased HBV DNA expression in palmitic acid - treated HepG2.2.15 cells. Additionally, ADAR1 inhibited the HBV DNA replication by upregulating miR-122, which is most abundant in the liver and mainly inhibits HBV DNA replication.

CONCLUSIONS

ADAR1 may act as a suppressor of HBV replication in palmitic acid -treated HepG2.2.15 cells by increasing miR-122 levels. Thus, ADAR1 may serve as a potential biomarker and therapeutic target for CHB with concurrent NAFLD.

Structural Basis and Function of the N Terminus of SARS-CoV-2 Nonstructural Protein 1

Nonstructural protein 1 (Nsp1) of severe acute respiratory syndrome coronaviruses (SARS-CoVs) is an important pathogenic factor that inhibits host protein translation by means of its C terminus. However, its N-terminal function remains elusive. Here, we determined the crystal structure of the N terminus (amino acids [aa] 11 to 125) of SARS-CoV-2 Nsp1 at a 1.25-Å resolution. Further functional assays showed that the N terminus of SARS-CoVs Nsp1 alone loses the ability to colocalize with ribosomes and inhibit protein translation. The C terminus of Nsp1 can colocalize with ribosomes, but its protein translation inhibition ability is significantly weakened. Interestingly, fusing the C terminus of Nsp1 with enhanced green fluorescent protein (EGFP) or other proteins in place of its N terminus restored the protein translation inhibitory ability to a level equivalent to that of full-length Nsp1. Thus, our results suggest that the N terminus of Nsp1 is able to stabilize the binding of the Nsp1 C terminus to ribosomes and act as a nonspecific barrier to block the mRNA channel, thus abrogating host mRNA translation.

Clinical effects of NTCP-inhibitor myrcludex B

With extensive research on the pathogenesis and treatment of hepatitis B virus (HBV) and hepatitis D virus (HDV) infections, the current treatment of interferon and nucleoside or nucleotide analogues provides reasonable control of viral replication in chronic hepatitis B (CHB). However, drug resistance may occur as a result of long-term treatment, and continuous covalently closed circular DNA (cccDNA) can cause disease relapse after drug withdrawal. Therefore, there is an urgent need for safe and effective antiviral drugs or methods to treat HBV and HDV infections. Myrcludex B is the first entry inhibitor that can inactivate HBV and HDV receptors, compete with HBV for the sodium-taurocholate co-transporting polypeptide, which has been identified as the bona fide receptor for HBV and HDV, block HBV infection in hepatocytes, and participate in HBV transcriptional suppression. Myrcludex B plays an important role in the inhibition of HBV replication and is a potential drug for phase III clinical trials. In this article, we review the progress on the efficacy and clinical application of myrcludex B in recent years.

Recent Advances in Hepatitis B Treatment

Hepatitis B virus infection affects over 250 million chronic carriers, causing more than 800,000 deaths annually, although a safe and effective vaccine is available. Currently used antiviral agents, pegylated interferon and nucleos(t)ide analogues, have major drawbacks and fail to completely eradicate the virus from infected cells. Thus, achieving a "functional cure" of the infection remains a real challenge. Recent findings concerning the viral replication cycle have led to development of novel therapeutic approaches including viral entry inhibitors, epigenetic control of cccDNA, immune modulators, RNA interference techniques, ribonuclease H inhibitors, and capsid assembly modulators. Promising preclinical results have been obtained, and the leading molecules under development have entered clinical evaluation. This review summarizes the key steps of the HBV life cycle, examines the currently approved anti-HBV drugs, and analyzes novel HBV treatment regimens.

Multifaceted Interaction Between Hepatitis B Virus Infection and Lipid Metabolism in Hepatocytes: A Potential Target of Antiviral Therapy for Chronic Hepatitis B

Hepatitis B virus (HBV) is considered a “metabolic virus” and affects many hepatic metabolic pathways. However, how HBV affects lipid metabolism in hepatocytes remains uncertain yet. Accumulating clinical studies suggested that compared to non-HBV-infected controls, chronic HBV infection was associated with lower levels of serum total cholesterol and triglycerides and a lower prevalence of hepatic steatosis. In patients with chronic HBV infection, high ALT level, high body mass index, male gender, or old age was found to be positively correlated with hepatic steatosis. Furthermore, mechanisms of how HBV infection affected hepatic lipid metabolism had also been explored in a number of studies based on cell lines and mouse models. These results demonstrated that HBV replication or expression induced extensive and diverse changes in hepatic lipid metabolism, by not only activating expression of some critical lipogenesis and cholesterolgenesis-related proteins but also upregulating fatty acid oxidation and bile acid synthesis. Moreover, increasing studies found some potential targets to inhibit HBV replication or expression by decreasing or enhancing certain lipid metabolism-related proteins or metabolites. Therefore, in this article, we comprehensively reviewed these publications and revealed the connections between clinical observations and experimental findings to better understand the interaction between hepatic lipid metabolism and HBV infection. However, the available data are far from conclusive, and there is still a long way to go before clarifying the complex interaction between HBV infection and hepatic lipid metabolism.

The NTCP p.Ser267Phe Variant Is Associated With a Faster Anti-HBV Effect on First-Line Nucleos(t)ide Analog Treatment

Sodium taurocholate cotransporting polypeptide (NTCP) acts as a cellular receptor for the hepatitis B virus infection of host hepatocytes. Previously, many studies confirmed that the NTCP p.Ser267Phe variant was a protective factor against HBV-related disease progression. We therefore designed this study to investigate whether the NTCP p.Ser267Phe variant exerts an additive anti-HBV effect in chronic hepatitis B (CHB) patients on mainstream NAs treatment. After propensity score matching (PSM), a total of 136 CHB patients were included, among whom 68 were heterozygous carriers and 68 were wild-type controls. Proportions of primary nonresponse, partial virological response, virological breakthrough and hepatitis B reactivation and the HBV DNA clearance rate at each time point were compared using the chi-square test. Kaplan-Meier analysis and matched t-tests were also performed to estimate the speed of viral clearance and serum HBV DNA reduction, respectively. The proportion of primary nonresponse was significantly lower in heterozygous carriers than in wild-type controls (p < 0.001), especially in patients using entecavir (p = 0.013). Specifically, heterozygous carriers achieved HBV DNA clearance faster than wild-type controls (log-rank p = 0.0198). HBV DNA levels were reduced more in heterozygous carriers after 12 weeks (p < 0.001) and 24 weeks (p = 0.006) of treatment, especially among patients using ETV. Here, our study demonstrated that heterozygous mutations in rs2296651 enhanced the antiviral response of first-line NAs and helped to explore the possibility of combining NAs and NTCP blockers for a better anti-HBV effect.

Repurposing of Antazoline Hydrochloride as an Inhibitor of Hepatitis B Virus DNA Secretion

Hepatitis B virus (HBV) belongs to Hepadnaviridae family and mainly infects hepatocytes, which can cause acute or chronic hepatitis. Currently, two types of antiviral drugs are approved for chronic infection clinically: interferons and nucleos(t)ide analogues. However, the clinical cure for chronic infection is still rare, and it is a huge challenge for all researchers to develop high-efficiency, safe, non-tolerant, and low-toxicity anti-HBV drugs. Antazoline hydrochloride is a first-generation antihistamine with anticholinergic properties, and it is commonly used to relieve nasal congestion and in eye drops. Recently, an in vitro high-throughput evaluation system was constructed to screen nearly 800 compounds from the Food and Drug Administration (FDA)-approved Drug Library. We found that arbidol hydrochloride and antazoline hydrochloride can effectively reduce HBV DNA in the extracellular supernatant in a dose-dependent manner, with EC₅₀ of 4.321 μmol/L and 2.910 μmol/L in HepAD38 cells, respectively. Moreover, the antiviral effects and potential mechanism of action of antazoline hydrochloride were studied in different HBV replication systems. The results indicate that antazoline hydrochloride also has a significant inhibitory effect on HBV DNA in the extracellular supernatant of Huh7 cells, with an EC₅₀ of 2.349 μmol/L. These findings provide new ideas for screening and research related to HBV agents.

HDAC11 restricts HBV replication through epigenetic repression of cccDNA transcription

Hepatitis B virus (HBV) infection remains an important public health problem worldwide. Covalently closed circular DNA (cccDNA) exhibits as an individual minichromosome and is the molecular basis of HBV infection persistence and antiviral treatment failure. In the current study, we demonstrated that histone deacetylase 11 (HDAC11) inhibits HBV transcription and replication in HBV-transfected Huh7 cells. By using an HBV in vitro infection system, HDAC11 was found to affect the transcriptional activity of cccDNA but did not affect cccDNA production. Chromatin immunoprecipitation (ChIP) assays were utilized to analyze the epigenetic modifications of cccDNA. The results show that HDAC11 specifically reduced the acetylation level of cccDNA-bound histone H3 but did not affect that of histone H4. Furthermore, HDAC11 overexpression decreased the levels of cccDNA-bound acetylated H3K9 (H3K9ac) and H3K27 (H3K27ac). In conclusion, HDAC11 restricts HBV replication through epigenetic repression of cccDNA transcription. These findings reveal the novel role of HDAC11 in HBV infection, further broadening our knowledge regarding the functions of HDAC11 and the roles of HDACs in the epigenetic regulation of HBV cccDNA.

Excellent safety and effectiveness of high-dose myrcludex-B monotherapy administered for 48 weeks in HDV-related compensated cirrhosis: A case report of 3 patients

Short-term administration of the entry inhibitor myrcludex-B (MyrB) has been shown to be safe and effective in phase II studies in patients coinfected with hepatitis B virus (HBV) and hepatitis delta virus (HDV). However, its effectiveness and safety are unknown during long-term and high-dose treatment of patients with compensated cirrhosis in real-life settings. Herein, we describe the first 3 European patients with HDV-related compensated cirrhosis who were treated with MyrB 10 mg/day for 48 weeks as a compassionate therapy. Liver function tests, bile acids, and virological markers were monitored every 4 weeks. HBV/HDV-specific T cell quantity (up to 48 and 36 weeks) and HBV RNA levels were also assessed in 2 cases. During MyrB treatment, HDV RNA levels progressively declined from 4.4 and 5.6 logs IU/ml to undetectability in 2 cases, and from 6.8 log copies/ml to 500 copies/ml for the other patient. Alanine aminotransferase normalised after 20, 12 and 28 weeks, respectively. A significant improvement in features of portal hypertension, liver function tests and alpha-fetoprotein levels were documented in 2 cases. In the male patient with histological and clinical stigmata of autoimmune hepatitis, IgG and immunoglobulins rapidly normalised. No significant changes in HBV surface antigen levels and circulating HBV/HDV-specific T cells were demonstrated; HBV DNA and HBV RNA levels remained undetectable throughout the study period. MyrB was well tolerated; patients remained fully asymptomatic despite a significant increase of bile acids. In conclusion, this report shows excellent safety and effectiveness of a 48-week course of MyrB 10 mg/day, combined with tenofovir disoproxil fumarate, for the treatment of HDV-related compensated cirrhosis.