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Background: Over 296 million people worldwide are living with chronic Hepatitis B (CHB) infection who require monitoring of viral activity and disease progression. Serum HBV RNA is a promising new biomarker in CHB management. No standardized method for serum HBV RNA quantification has been established. Objectives: To develop and validate, both analytically and clinically, a 3′ RACE RT-qPCR assay for quantification of serum HBV RNA. Study design: The 3′ RACE RT-qPCR method was developed using published primers. The analytical limit of detection and quantification, linearity, inter- and intra-assay repeatability, and clinical specificity and sensitivity were evaluated using synthetic pre-genomic RNA and specimens from various patient populations. Intra- and inter-laboratory ring trials involving three laboratories were completed. Results: The 3′ RACE RT-qPCR assay dynamic range is 25 to 108 copies/µL of synthetic RNA. Theoretical and measured serum HBV RNA quantities from a serially diluted sample showed excellent linearity (R2=0.9795). The inter- and intra-assay repeatability were 94.91% and 95.12%, respectively. Clinical specificity and sensitivity were 100% and 90%, respectively, in treated patients. Inter-laboratory analysis demonstrated moderate to high agreement among participating laboratories (κ = 0.581 to 0.867). High agreement was also observed between both operators participating in the intra-laboratory evaluation (κ = 0.867). Conclusions: Our methodology for the quantification of serum HBV RNA is specific and repeatable and employs a biologically relevant RNA standard suitable for medium throughput laboratories. Method standardization is required to facilitate the comparison of studies and better understand the clinical role of this novel biomarker.

Objectives: To investigate the factors and virological significance of serum hepatitis B virus (HBV) pregenomic RNA (pgRNA) status after long-term antiviral therapy with nucleos(t)ide analogues (NAs) in patients with chronic hepatitis B (CHB). Methods: In total, 51 treatment-naïve patients with CHB were included in the study. Clinical data were collected at baseline, during 5 years and at year 10 of NA treatment. Serum HBV pgRNA status of 51 patients was determined at year 5. Results: At year 5, 45% of the patients remained positive for HBV pgRNA. There were significant differences in baseline hepatitis B e antigen (HBeAg) status, HBV DNA load and hepatitis B surface antigen (HBsAg) levels between patients testing positive and negative for HBV pgRNA at year 5. Serum HBV pgRNA status and serum HBV DNA load were correlated after 5 years of NA treatment (r = 0.347, P = 0.013). Being HBV pgRNA positive at year 5 was an independent risk factor for sustainedly undetectable HBV DNA after 10 years of NA treatment (odds ratio 13.638, 95% confidence interval 1.32–140.81; P = 0.028). Furthermore, HBV pgRNA status at year 5 was associated with HBV DNA re-appearance at year 10 (P = 0.009). Conclusions: HBV pgRNA status at year 5 can reveal HBV covalently closed circular DNA (cccDNA) activity, and HBV pgRNA positivity after long-term antiviral therapy may indicate higher transcriptional activity of HBV cccDNA. Long-term dynamic monitoring of HBV pgRNA should be considered.

Background & Aims: HBV nucleos(t)ide reverse transcriptase inhibitors (NrtIs) do not completely suppress HBV replication. Previous reports indicate persistent viremia during NrtI treatment despite HBV DNA being undetectable. HBV core inhibitors may enhance viral suppression when combined with NrtIs. This phase II trial (NCT03576066) evaluated the efficacy and safety of the investigational core inhibitor, vebicorvir (VBR), in virologically- suppressed patients on NrtIs., Methods: Non-cirrhotic, NrtI-suppressed patients with chronic HBV were randomised to VBR 300 mg once daily or matching placebo (PBO) for 24 weeks. Treatment was stratified by hepatitis B e antigen (HBeAg) status. The primary endpoint was change from Baseline in serum HBeAg or hepatitis B surface antigen (HBsAg) after 24 weeks., Results: Of 73 patients enrolled, 47 were HBeAg positive and 26 were HBeAg negative. In HBeAg-positive and -negative patients, there were no differences in the change from Baseline at Week 24 for HBsAg or HBeAg. Using a novel, high-sensitivity assay to detect HBV DNA, a greater proportion of patients with detectable HBV DNA at Baseline achieved undetectable HBV DNA at Week 24 in the VBR+NrtI vs. PBO+NrtI group. In HBeAg-positive patients, a greater change from Baseline in HBV pregenomic (pg)RNA was observed at Week 24 with VBR+NrtI vs. PBO+NrtI. Treatment-emergent adverse events (TEAEs) in VBR+NrtI patients included upper respiratory tract infection, nausea, and pruritus. No serious adverse events, Grade 4 TEAEs, or deaths were reported., Conclusions: In this 24-week study, VBR+NrtI demonstrated a favourable safety and tolerability profile. While there were no significant changes in viral antigen levels, enhanced viral suppression was demonstrated by greater changes in DNA and pgRNA with the addition of VBR compared to NrtI alone., Clinical Trials Number: NCT03576066., Lay Summary: Core inhibitors represent a novel approach for the treatment of chronic hepatitis B virus (HBV) infection, with mechanisms of action distinct from existing treatments. In this study, vebicorvir added to existing therapy reduced HBV replication to a greater extent than existing treatment and was generally safe and well tolerated., Competing Interests: Conflict of interest Man-Fung Yuen reports being an advisor/consultant for and/or having received grant/research support from AbbVie, Aligos Therapeutics, Antios Therapeutics, Arbutus Biopharma, Arrowhead Pharmaceuticals, Assembly Biosciences, Bristol-Myers Squibb, Clear B Therapeutics, Dicerna Pharmaceuticals, Finch Therapeutics, Fujirebio Incorporation, GlaxoSmithKline, Gilead Sciences, Immunocore, Janssen, Merck Sharp and Dohme, Roche, Springbank Pharmaceuticals, Silverback Therapeutics, Sysmex Corporation, and Vir Biotechnology. Kosh Agarwal reports being on the advisory board, a consultant, and a speaker for AbbVie, Assembly Biosciences, Aligos, Arbutus, Bristol-Myers Squibb, Gilead Sciences, Immunocore, Janssen, Merck, Novartis, Roche, Sobi, Shinoigi, and Vir; and receiving grants from Bristol-Myers Squibb, Gilead Sciences, and Roche. Xiaoli Ma reports being a consultant and being on the speakers bureau for Gilead Sciences. Tuan T. Nguyen reports receiving research grant support from Gilead Sciences and Assembly Biosciences. Eugene R. Schiff reports receiving research and grant support from Assembly Biosciences, Celgene, and the University of Florida (TARGET) and receives royalties from the Schiff Diseases of the Liver, 12th edition. Hie-Won L. Hann reports serving on the National Advisory Board and receives research grant support from Gilead Sciences. Douglas T. Dieterich reports being a consultant for Gilead Sciences and Intercept Pharmaceuticals. Ronald G. Nahass reports having served on advisory boards and as a speaker for Gilead Sciences, Merck, and Janssen; and having conducted research for Gilead Sciences, Merck, Janssen, and AbbVie. James S. Park reports receiving research grants from Assembly Biosciences and GlaxoSmithKline and consulting fees from Gilead Sciences. Sing Chan reports receiving clinical trial-related payments from Assembly Biosciences. Steven-Huy Han reports being a consultant and being on the speakers bureau for Gilead Sciences. Edward J. Gane reports serving on advisory boards for AbbVie, Aligos Therapeutics, Arbutus Biopharma, Arrowhead Pharmaceuticals, Assembly Biosciences, Avilia Therapeutics, Clear B Therapeutics, Dicerna, Enanta Pharmaceuticals, Finch Therapeutics, Gilead Sciences, GlaxoSmithKline, Immunocore, Janssen, Roche, Silverback, and Vir Bio. and having served as a speaker for Gilead Sciences, AbbVie, and Roche. Michael Bennett reports having no conflicts of interest. Katia Alves reports being a former employee of and holding stock interest in Assembly Biosciences. Marc Evanchik reports having been an employee of and holding stock interest in Assembly Biosciences and is currently an employee of Edgewise Therapeutics. Ran Yan reports being an employee of and holding stock interest in Assembly Biosciences. Qi Huang reports being an employee of and holding stock interest in Assembly Biosciences. Uri Lopatin reports being a former employee and holding stock interest in Assembly Biosciences. Richard Colonno reports being an employee of and holding stock interest in Assembly Biosciences. Julie Ma reports being an employee of and holding stock interest in Assembly Biosciences. Steven J. Knox reports being an employee of and holding stock interest in Assembly Biosciences. Luisa M. Stamm reports being an employee of and holding stock interest in Assembly Biosciences. Maurizio Bonacini reports being a member of the speaking bureau for Intercept Pharmaceuticals, Gilead Sciences, and AbbVie and has received research support from Assembly Biosciences, Intercept Pharmaceuticals, Viking Therapeutics, and Boehringer Ingelheim. Ira M. Jacobson reports being a consultant or on advisory boards for AbbVie, Aligos Therapeutics, Arbutus Biopharma, Gilead Sciences, Janssen, Madrigal and Virion; having conducted research (all payments to institution) for Assembly Biosciences, Bristol-Myers Squib, Eli Lilly, Enanta Pharmaceuticals, Gilead Sciences, Janssen, Merck, and Novo Nordisk; receiving payment from the Chronic Liver Disease Foundation for manuscript preparation; and reports participation on a Data Safety Monitoring Board for GSK, Redhill, Galmed, NeuroBo, and Arrowhead Pharmaceuticals. Walid S. Ayoub reports being a member of the speaking bureau for both Gilead Sciences and Intercept Pharmaceuticals and has conducted research for Assembly Biosciences, Intercept Pharmaceuticals, Enanta Pharmaceuticals, and Gilead Sciences. Frank Weilert reports being a study investigator for AbbVie. Natarajan Ravendhran reports advising, being on the speakers’ bureau for, and receiving grants from Gilead Sciences and AbbVie; being on the speakers' bureau for Salix and Onyx; and having received grants from Bristol-Myers Squibb and Merck. Alnoor Ramji reports receiving grant support, lecture fees, and advisory board fees from AbbVie, Celgene, Gilead Sciences, Intercept Pharmaceuticals, Novartis, and Merck. Paul Yien Kwo reports being an advisor/consultant for AbbVie, Aligos Therapeutics, Antios Therapeutics, Enanta Pharmaceuticals, Gilead Sciences, Janssen, and receives grant/research support from Assembly Biosciences, Arrowhead Pharmaceuticals, Eiger Biopharmaceuticals, Bristol Myer Squibb, Altimmune, and Target Registries. Magdy Elkhashab reports receiving grants from AbbVie, Bristol-Myers Squibb, Eisai, Gilead Sciences, and Roche; and serving on advisory boards for AbbVie, Bristol-Myers Squibb, Gilead Sciences, and Merck. Tarek Hassanein reports being on the advisory committee, review panel, or consulting for AbbVie, Bristol-Myers Squibb, Gilead Sciences, Mallinckrodt Pharmaceuticals, Merck, and Organovo and receiving research support from AbbVie, Allergan, Cytodyn, Assembly Biosciences, Astra Zeneca, Boehringer Ingelheim, Bristol-Myers Squibb, CARA, DURECT Corporation, Enanta Pharmaceuticals, Galectin Therapeutics, Gilead Sciences, Grifols, Intercept Pharmaceuticals, Janssen, Merck, Mirum, Novartis, Novo Nordisk, Nucorion Pharmaceuticals, Pfizer, Salix Pharmaceuticals, Sonic Incytes, Terns Pharmaceuticals, and Valeant. Ho S. Bae reports having consultancy agreements with and receiving research support from Bristol-Myers-Squibb and Gilead Sciences. Jacob P. Lalezari reports having no conflicts of interest. Scott K. Fung reports receiving fees for speaking & teaching and/or serving on advisory committees for AbbVie, Assembly Biosciences, Gilead Sciences, Janssen, and Springbank Pharma. Mark S. Sulkowski reports receiving grants from AbbVie, Assembly Biosciences, Gilead Sciences, Janssen, and the National Institutes of Health; and receiving personal fees from AbbVie, Antios Therapeutics, Arbutus Biopharma, Atea Pharmaceuticals, Gilead Sciences, FH360, and Immunocore. Please refer to the accompanying ICMJE disclosure forms for further details., (Copyright © 2022 The Authors. Published by Elsevier B.V. All rights reserved.)

Objectives: To investigate the factors and virological significance of serum hepatitis B virus (HBV) pregenomic RNA (pgRNA) status after long-term antiviral therapy with nucleos(t)ide analogues (NAs) in patients with chronic hepatitis B (CHB)., Methods: In total, 51 treatment-naïve patients with CHB were included in the study. Clinical data were collected at baseline, during 5 years and at year 10 of NA treatment. Serum HBV pgRNA status of 51 patients was determined at year 5., Results: At year 5, 45% of the patients remained positive for HBV pgRNA. There were significant differences in baseline hepatitis B e antigen (HBeAg) status, HBV DNA load and hepatitis B surface antigen (HBsAg) levels between patients testing positive and negative for HBV pgRNA at year 5. Serum HBV pgRNA status and serum HBV DNA load were correlated after 5 years of NA treatment (r = 0.347, P = 0.013). Being HBV pgRNA positive at year 5 was an independent risk factor for sustainedly undetectable HBV DNA after 10 years of NA treatment (odds ratio 13.638, 95% confidence interval 1.32-140.81; P = 0.028). Furthermore, HBV pgRNA status at year 5 was associated with HBV DNA re-appearance at year 10 (P = 0.009)., Conclusions: HBV pgRNA status at year 5 can reveal HBV covalently closed circular DNA (cccDNA) activity, and HBV pgRNA positivity after long-term antiviral therapy may indicate higher transcriptional activity of HBV cccDNA. Long-term dynamic monitoring of HBV pgRNA should be considered., (Copyright © 2021 The Author(s). Published by Elsevier Ltd.. All rights reserved.)

Background & Aims: The Hepatitis B Virus (HBV) may gain entry into non-liver cells but does not actively replicate in them. We investigated the possibility that these cells possess mechanisms that block HBV core promoter (HBVCP) transcription, specifically absent in liver cells, which together with other liver-specific mechanisms, such as sodium-taurocholate cotransporting polypeptide-mediated entry, enable liver cells to effectively produce HBV., Methods: Liver and non-liver cell lines were screened for their capacity to activate the HBVCP and synthesize pre-genomic RNA (pgRNA). Transcription regulators differentially expressed between cells with active or inactive HBVCP were determined by human transcriptome array. Slug (SNAI2) and SRY-related HMG box 7 (SOX7) transcriptional repressors were identified and shown to bind specifically to the HBVCP by electrophoretic mobility shift assay. The resultant inhibitory effect on HBVCP transcription was validated using luciferase reporter and assays for pgRNA, HBcAg and cccDNA accumulation in cells with HBV replicon and HBV infection models. To further confirm their specific activity, short peptide mimetics generated from Slug zinc-finger domains and SOX7 HMG-box were generated., Results: The HBVCP was found to be active in liver and selected non-liver cells. These cells have low/negligible expression of Slug and SOX7, which inhibit HBVCP transcription specifically by binding at the pgRNA initiator site and competitively displacing hepatocyte nuclear factor 4α, respectively. Overexpression of Slug and/or SOX7 specifically reduced HBVCP transcription, significantly diminishing pgRNA synthesis, HBcAg and cccDNA accumulation in HBV-infected primary human hepatocytes. Similar results were obtained with Slug and SOX7 stapled peptides individually, which were even more potent in combination., Conclusions: Slug and SOX7 are transcriptional repressors that bind specifically to the HBVCP. Their absence or weak expression in liver cells contribute to the favorable host environment for the active and efficient production of HBV., Lay Summary: Hepatitis B virus (HBV) replication occurs efficiently in human liver because of the specificity of viral uptake receptors and presence of numerous liver-enriched transcription activators. Herein, we show that the specific lack of transcriptional inhibitory mechanisms in liver cells also contribute to effective HBV production. HBV replication is kept low in non-liver cells as transcriptional repressors Slug and SRY-related HMG box 7 (SOX7) actively bind to the transcriptional initiator and displace transcription activators, respectively, within the HBV core promoter., (Copyright © 2017 European Association for the Study of the Liver. Published by Elsevier B.V. All rights reserved.)

Hepatitis B virus (HBV) infection is one of the major global health problems, especially in economically under-developed or developing countries. HBV infection can lead to a number of clinical outcomes including chronic infection, cirrhosis and liver cancer. It ranks among the top 10 causes of death, being responsible for around 1 million deaths every year. Despite the availability of a highly efficient vaccine and potent antiviral agents, HBV infection still remains a significant clinical problem, particularly in those high endemicity areas where vaccination of large populations has not been possible due to economic reasons. Although HBV is among the smallest viruses in terms of virion and genome size, it has numerous unique features that make it completely distinct from other DNA viruses. It has a partially double stranded DNA with highly complex genome organization, life cycle and natural history. Remarkably distinct from other DNA viruses, it uses an RNA intermediate called pregenomic RNA (pgRNA) and reverse transcriptase for its genome replication. Genome replication is accomplished by a complex mechanism of primer shifting facilitated by direct repeat sequences encoded in the genome. Further, the genome has evolved in such a manner that every single nucleotide of the genome is used for either coding viral proteins or used as regulatory regions or both. Moreover, it utilizes internal in-frame translation initiation codons, as well as different reading frames from the same RNA to generate different proteins with diverse functions. HBV also shows considerable genetic variability which has been related with clinical outcomes, replication potential, therapeutic response etc. This review aims at reviewing fundamental events of the viral life cycle including viral replication, transcription and translation, from the molecular standpoint, as well as, highlights the clinical relevance of genetic variability of HBV.