Hepatitis B virus resistance to nucleos(t)ide analogues

Inactivation of the key ORFs of HBV for antiviral therapy by non-cleavage base editing

OBJECTIVES

Hepatitis B virus (HBV) infection is the key cause of chronic hepatitis, liver cirrhosis, and hepatocellular carcinoma. Currently available anti-HBV drugs are more or less defective owing to the unremovable covalently closed circular DNA (cccDNA). Thus, CRISPR/Cas9 is a promising therapeutic strategy for anti-HBV therapy. Double-strand breaks (DSBs) and uncontrolled genomic rearrangements occur inevitably. In this study, we aimed to use base editors to control HBV infection.

METHODS

Base editors precisely instal targeted point mutations without requiring DSBs or donor DNA templates, and without relying on homology-directed repair (HDR) or nonhomologous end joining (NHEJ). Adenine base editors (ABEs) and cytosine base editors (CBEs) catalyse A• T to G •C and C• G to T •A conversions, respectively. In this study, to control HBV replication by modifying and inactivating key HBV genes, recently developed CRISPR/Cas-mediated SpRY-ABE8e and CBE4-max were utilised to falsify and invalidate the ATG initiation codons of the S, Pre-S1, PreS2, C, Pre-C, X, and P genes.

RESULTS

The ATG initiation codons of HBV genes were edited by ABE/CBE. The expected point mutations were successfully introduced, resulting in the simultaneous suppression of HBV antigen expression and replication to varying degrees.

CONCLUSIONS

Our study focused on clearing HBV using base and provided experimental and theoretical evidence for the treatment of chronic HBV infection. Thus, base editing is a potential strategy for curing CHB by permanently inactivating the integrated DNA and cccDNA without using DSBs.

EASL Clinical Practice Guidelines on the management of hepatitis B virus infection

The updated EASL Clinical Practice Guidelines on the management of hepatitis B virus (HBV) infection provide comprehensive, evidence-based recommendations for its management. Spanning ten thematic sections, the guidelines address diagnostics, treatment goals, treatment indications, therapeutic options, hepatocellular carcinoma surveillance, management of special populations, HBV reactivation prophylaxis, post-transplant care, HBV prevention strategies, and finally address open questions and future research directions. Chronic HBV remains a global health challenge, with over 250 million individuals affected and significant mortality due to cirrhosis and hepatocellular carcinoma. These guidelines emphasise the importance of early diagnosis, risk stratification based on viral and host factors, and tailored antiviral therapy. Attention is given to simplified algorithms, vaccination, and screening to support global HBV elimination targets. The guidelines also discuss emerging biomarkers and evolving definitions of functional and partial cure. Developed through literature review, expert consensus, and a Delphi process, the guidelines aim to equip healthcare providers across disciplines with practical tools to optimise HBV care and outcomes worldwide.

Hepatitis B virus resistance to nucleos(t)ide analogue therapy: WHO consultation on questions, challenges, and a roadmap for the field

In this Review, we summarise outputs from a multidisciplinary consultation convened by WHO between July 11 and 13, 2023, to discuss hepatitis B virus (HBV) drug resistance (HBVDR). Treatment of chronic HBV infection with highly effective nucleos(t)ide analogue agents, tenofovir and entecavir, is a crucial intervention that supports the global goal of elimination of HBV infection as a public health threat. The risk of HBVDR as a threat to treatment outcomes is currently considered low from a public health perspective; however, drug resistance can influence individual outcomes, particularly among those who are treatment-experienced. We highlight the need to develop appropriate prevention, monitoring, and surveillance approaches for HBVDR, to support investment in the global scale-up of HBV diagnosis and treatment. Recommendations for the HBVDR field will ultimately be incorporated into a WHO integrated Global Action Plan for drug-resistant HIV, viral hepatitis, and priority sexually transmitted infections.

Performance evaluation of a fully automated deep sequencing platform for hepatitis B genotyping and resistance testing

BACKGROUND

Treatment of chronic hepatitis B infection requires lifelong administration of nucleos(t)ide analogues with a high barrier to resistance and effective viral suppression. The major limitation of lifelong therapy is the possible selection of drug-resistant hepatitis B virus (HBV) strains. International Liver Society guidelines recommend that hepatitis B resistance testing must be performed by a reference laboratory.

OBJECTIVES

Performance of the deep sequencing-based ViroKey® SQ FLEX Genotyping Assay for the determination of HBV genotypes and resistance profiles were evaluated.

PATIENTS AND METHODS

Plasma samples collected from patients with chronic hepatitis B have been sequenced by two methods including Sanger (population) sequencing of a portion of the P/S overlapping gene and the deep sequencing-based ViroKey® SQ FLEX Genotyping Assay (Vela Diagnostics).

RESULTS

A high concordance rate with population sequencing was found regardless of HBV genotypes. Deep sequencing with the Sentosa platform was more sensitive than population sequencing in detecting minor variant populations.

CONCLUSIONS

The deep sequencing-based ViroKey® SQ FLEX Genotyping Assay can be confidently used in clinical practice for hepatitis B genotyping and resistance testing.

The first case of transfusion-transmitted hepatitis B virus genotype I in Japan

BACKGROUND

In Japan, the risk of transfusion-transmitted hepatitis B virus (TT-HBV) infection has been reduced since 2014 by implementing individual donation nucleic acid amplification testing (ID-NAT).

CASE REPORT

A male repeat blood donor in his 20s converted positive for HBV DNA and hepatitis B surface antigen. Red cell concentrate from his previous donation had been transfused into a woman in her 70s. Her serum showed HBV DNA positivity 62 days after transfusion. HBV genome sequences across two regions were shown to be identical in the donor and recipient. The HBV full-length genome sequence from the donor belonged to nonindigenous subgenotype I1. It contained double mutations A1762T and G1764A, which are associated with hepatocellular carcinoma development. The donor had no history of traveling abroad within 126 days prior to the index donation, so he was probably infected with HBV in Japan.

DISCUSSION

Including this case, nine cases of TT-HBV from eight blood donations have been detected in Japan since the introduction of ID-NAT. Seven of the eight TT-HBV-related donations had HBV subgenotypes that were exotic to Japan. Exotic HBV strains spreading in Japan pose a risk of TT-HBV owing to ongoing acute HBV infection with these strains.

Evaluation of genotype characteristics and drug resistance mutations in patients with chronic hepatitis B

Hepatitis B is one of the public health priorities worldwide, especially in the Southwest China. Our study aimed to investigate the relationship between genotypes and drug resistance mutations among HBV patients in Southwest China, with the objective of providing guidance for clinical antiviral treatment. A total of 4266 chronic hepatitis B (CHB) patients treated in the Qianjiang Hospital of Chongqing University were included in our study from 2014 to 2020. Both genotypes and drug-resistant mutations of CHB patients were determined by polymerase chain reaction (PCR). Genotype B and genotype C were the main HBV genotypes in our study. We found 54 mutation patterns, including 9 single-site mutations and 45 multiple-site mutations, accounting for 57.64% and 42.36%, respectively. rtM204I/V/S (485/1936) was the most common single-site mutation type, and rtL180M + rtM204I/V (482/1936) was the most common multiple-site mutation type. 1372 CHB patients were resistant to LAM + LDT, and 342 CHB patients were resistant to ADV. There was only 1 CHB patient who exhibited resistance to LAM + LDT + ADV + ETV, with a specific mutation pattern of rtA181T + rtT184L + rtM204V. Our study demonstrated trends in genetic mutations and drug resistance in CHB patients to enable timely adjustment of antiviral treatment strategies.

A systematic review and meta-analysis of the risk of hepatitis B virus (HBV) resistance in people treated with entecavir or tenofovir

BACKGROUND

As nucleos/tide analogue (NA) therapy (e.g. entecavir and tenofovir) for chronic Hepatitis B virus (HBV) infection becomes more widely indicated and available, understanding drug resistance is essential. A systematic review to quantify resistance to these agents has not previously been undertaken.

METHODS

We performed a systematic review and random-effects meta-analysis to estimate the risk of HBV resistance to entecavir and tenofovir. We searched nine databases up to 29-Aug-23. We included studies of HBV infection featuring >10 individuals, written in English, reporting treatment ≥48 weeks, with assessment of HBV resistance based on viral sequence data. Data were analysed according to prior exposure history to NA, and choice of NA agent. Analyses were performed in R.

FINDINGS

62 studies involving a total of 12,358 participants were included. For entecavir, in treatment-naive individuals (22 studies; 4326 individuals), resistance increased over time to 0.9 % at ≥5 years (95 %CI 0.1-2.3 %), and resistance was increased in NA-experienced individuals (18 studies; 1112 individuals), to 20.1 % (95 %CI 1.6-50.1 %) at ≥5 years. For tenofovir, pooled resistance risk was 0.0 % at all time points, whether previously NA naive (11 studies; 3778 individuals) or experienced (19 studies; 2059 individuals). There was a lack of consistent definitions, poor global representation and insufficient metadata to support subgroup analysis.

INTERPRETATION

We have generated the first pooled estimates of HBV entecavir and tenofovir resistance over time. HBV resistance to entecavir in treatment-experienced groups in particular may represent a clinical and public health challenge. To date, tenofovir appears to have an excellent resistance profile, but due to data gaps, we caution that existing studies under-estimate the true real-world risk of resistance. Robust prospective data collection is crucial to reduce health inequities and reduce blind-spots in surveillance as treatment is rolled out more widely.

Viral Hepatitis: Host Immune Interaction, Pathogenesis and New Therapeutic Strategies

Viral hepatitis is a major cause of liver illness worldwide. Despite advances in the understanding of these infections, the pathogenesis of hepatitis remains a complex process driven by intricate interactions between hepatitis viruses and host cells at the molecular level. This paper will examine in detail the dynamics of these host-pathogen interactions, highlighting the key mechanisms that regulate virus entry into the hepatocyte, their replication, evasion of immune responses, and induction of hepatocellular damage. The unique strategies employed by different hepatitis viruses, such as hepatitis B, C, D, and E viruses, to exploit metabolic and cell signaling pathways to their advantage will be discussed. At the same time, the innate and adaptive immune responses put in place by the host to counter viral infection will be analyzed. Special attention will be paid to genetic, epigenetic, and environmental factors that modulate individual susceptibility to different forms of viral hepatitis. In addition, this work will highlight the latest findings on the mechanisms of viral persistence leading to the chronic hepatitis state and the potential implications for the development of new therapeutic strategies. Fully understanding the complex host-pathogen interactions in viral hepatitis is crucial to identifying new therapeutic targets, developing more effective approaches for treatment, and shedding light on the mechanisms underlying progression to more advanced stages of liver damage.

Efficacy and safety of therapeutic vaccines for the treatment of chronic hepatitis B: A systematic review and meta-analysis of randomized controlled trials update

BACKGROUND

Most people diagnosed with chronic hepatitis B (CHB) need treatment to help reduce the risk of liver disease and limit disease transmission. Therapeutic vaccine (TV) candidates have been under study for their clinical effects on inducing HBV-specific host immune responses. This review aimed to systematically synthesize updated evidence on the efficacy and safety of TVs in patients with CHB.

METHODS

This systematic review was performed by searching different databases from January to February 2021. Completed randomized controlled trials that reported TVs' efficacy and/or safety for treating CHB compared with the standard of care (SOC) or placebo were included. Efficacy and safety estimates were reported as the logarithm of the odds ratio and risk differences, respectively. I2 > 50% was considered significant heterogeneity. Significant publication bias was considered when Egger's test P value < .10. The risk of bias was assessed using the Cochrane Risk of Bias tool. The GRADE methodology was used to assess the certainty of the evidence for each outcome.

RESULTS

Twenty-four articles with 2889 pooled samples were included. TVs made a significant difference in hepatitis B envelope antigen (HBeAg) SC (log OR = 0.76, P = .01) and (log OR = 0.40, P = .03) compared to placebo and combination therapy, respectively. HBeAg SC was significantly affected by TVs at the end of follow up (log OR = 0.49, P = .01), with significant HBsAg mean difference (MD = -0.62, P = .00). At the end of treatment, the TVs had no significant effect on HBV DNA negativity over the SOC (log OR = 0.62, P = .09) or placebo (log OR = -0.07, P = .91). TVs do not significantly affect the risk of serious adverse events (RD 0.02, 95% CI 0.00-0.04).

CONCLUSION

In patients with CHB, TVs had significant effects on HBeAg SC compared to the SOC or placebo. There was no significant difference between serious adverse events. TVs are promising treatment strategy to overcome CHB.

MicroRNA levels in patients with chronic hepatitis B virus and HIV coinfection in a high-prevalence setting; KwaZulu-Natal, South Africa

BACKGROUND

Hepatitis B virus (HBV) and human immunodeficiency virus (HIV) co-infection are significant public health issues, despite the availability of an effective HBV vaccine for nearly three decades and the great progress that has been made in preventing and treating HIV. HBV and HIV both modulate micro-ribonucleic acids (microRNA) expression to support viral replication. The aim of this study was to describe the pattern of microRNA expression in patients coinfected with chronic HBV and HIV with varying disease severity, as indicated by Hepatitis B e antigen (HBeAg) status, HBV viral load, alanine transaminase (ALT) levels, and HIV viral load.

METHODS

Plasma microRNAs, specific to HBV, were measured by quantitative real-time polymerase chain reaction (qRT-PCR) in HBV and HIV-negative healthy controls (n = 23) and patients coinfected with chronic HBV-HIV (n = 50). MicroRNA expression levels were compared between patients with high vs low HBV viral load, HBeAg positive vs HBeAg negative, high vs low ALT levels, and high vs low HIV viral load. Additionally, HBV viral load, ALT levels, and HIV viral load were correlated with microRNA expression levels.

RESULTS

Significantly higher expression levels of selected microRNAs were observed in chronic HBV-HIV coinfected patients compared to healthy controls. Significantly higher expression levels of hsa-miR-122-5p, hsa-miR-192-5p, and hsa-miR-193b-3p were observed in patients with high HBV viral load compared with low HBV viral load patients, and the levels of these microRNAs were correlated with HBV viral load levels. Significantly higher levels of hsa-miR-15b-5p and hsa-miR-181b-5p were observed in HBeAg-negative patients.

CONCLUSION

This study demonstrates the potential use of hsa-miR-15b-5p, hsa-miR-122-5p, hsa-miR-181b-5p, hsa-miR-192-5p and hsa-miR-193b-3p as additional diagnostic biomarkers in chronic HBV disease progression.

Social, clinical and biological barriers to hepatitis B virus suppression with nucleos/tide analogue therapy: who is at risk and what should we do about it?

Optimising treatment outcomes for people living with hepatitis B virus (HBV) is key to advancing progress towards international targets for the elimination of viral hepatitis as a public health threat. Nucleos/tide analogue agents (most commonly tenofovir or entecavir) are well-tolerated and suppress viraemia effectively in the majority of those who are offered therapy. However, outcomes are not consistent, and we explore the factors that may contribute to incomplete therapeutic responses. We discuss situations in which therapy is not accessible, affordable or acceptable, reflecting the impact of social, cultural and economic barriers, stigma and discrimination, low awareness, poor access to health systems and comorbidity. These challenges are amplified in certain vulnerable populations, increasing the risk of adverse outcomes-which include liver cirrhosis and hepatocellular carcinoma-among people who already experience marginalisation and health inequities. We also tackle the physiological and biological mechanisms for incomplete virological suppression in individuals receiving HBV treatment, considering the possible impact of inadequate tissue drug levels, poor drug-target avidity and genomic resistance. These factors are interdependent, leading to a complex landscape in which socioeconomic challenges increase the challenge of consistent daily therapy and set the scene for selection of drug resistance. By putting a spotlight on this neglected topic, we aim to raise awareness, prompt dialogue, inform research and advocate for enhanced interventions. As criteria for HBV treatment eligibility relax, the population receiving therapy will expand, and there is a pressing need to optimise outcomes and close the equity gap.

Multiple risk factors for persistent HBV viraemia in an adult receiving nucleos/tide analogue therapy

Diagnosing and treating chronic hepatitis B virus (HBV) infection are key interventions to support progress towards elimination of viral hepatitis by 2030. Although nucleos/tide analogue (NA) therapy is typically highly effective, challenges remain for viral load (VL) suppression, including medication access, incomplete adherence and drug resistance. We present a case of a long-term HBV and HIV coinfected adult prescribed with sequential NA therapy regimens, with episodes of breakthrough viraemia. Multiple factors contribute to virological breakthrough, including exposure to old NA agents, initial high HBV VL, therapy interruptions, intercurrent illnesses and potential contribution from resistance mutations. The case underscores the importance of individualised treatment approaches and adherence support in achieving HBV suppression. Furthermore, it emphasises the need for improved clinical pathways addressing education, support and access to care, particularly for marginalised populations. Comprehensive data collection inclusive of under-represented individuals is crucial for maintaining retention in the care cascade and informing effective interventions.

In vitro selection and analysis of SARS-CoV-2 nirmatrelvir resistance mutations contributing to clinical virus resistance surveillance

To facilitate the detection and management of potential clinical antiviral resistance, in vitro selection of drug-resistant severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) against the virus Mpro inhibitor nirmatrelvir (Paxlovid active component) was conducted. Six Mpro mutation patterns containing T304I alone or in combination with T21I, L50F, T135I, S144A, or A173V emerged, with A173V+T304I and T21I+S144A+T304I mutations showing >20-fold resistance each. Biochemical analyses indicated inhibition constant shifts aligned to antiviral results, with S144A and A173V each markedly reducing nirmatrelvir inhibition and Mpro activity. SARS-CoV-2 surveillance revealed that in vitro resistance-associated mutations from our studies and those reported in the literature were rarely detected in the Global Initiative on Sharing All Influenza Data database. In the Paxlovid Evaluation of Protease Inhibition for COVID-19 in High-Risk Patients trial, E166V was the only emergent resistance mutation, observed in three Paxlovid-treated patients, none of whom experienced COVID-19-related hospitalization or death.

Sustained Liver HBsAg Loss and Clonal T- and B-Cell Expansion upon Therapeutic DNA Vaccination Require Low HBsAg Levels

BACKGROUND

Suppression of HBV DNA, inhibition of HBV surface (HBsAg) production and therapeutic vaccination to reverse HBV-specific T-cell exhaustion in chronic HBV patients are likely required to achieve a functional cure. In the AAV-HBV mouse model, therapeutic vaccination can be effective in clearing HBV when HBsAg levels are low. Using a single-cell approach, we investigated the liver immune environment with different levels of HBsAg and sustained HBsAg loss through treatment with a GalNAc-HBV-siRNA followed by therapeutic vaccination.

METHODS

AAV-HBV-transduced C57BL/6 mice were treated with GalNAc-HBV-siRNA to lower HBsAg levels and then vaccinated using a DNA vaccine. We used single-cell RNA and V(D)J sequencing to understand liver immune microenvironment changes.

RESULTS

GalNAc-HBV-siRNA, followed by therapeutic vaccination, achieved sustained HBsAg loss in all mice. This was accompanied by CD4 follicular helper T-cell induction, polyclonal activation of CD8 T cells and clonal expansion of plasma cells that were responsible for antibody production.

CONCLUSIONS

This study provides novel insights into liver immune changes at the single-cell level, highlighting the correlation between induced reduction of HBsAg levels and clonal expansion of CD4, CD8 T cells and plasma cells in the liver upon HBV siRNA and subsequent therapeutic vaccination.

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

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

In vitro evaluation of tropolone absorption, metabolism, and clearance

Tropolone compounds can inhibit hepatitis B virus (HBV) replication at sub-micromolar levels and are synergistic upon co-treatment with nucleos(t)ide analog drugs. However, only a few compounds within this chemotype have been screened for their pharmacological properties. Here, we chose 36 structurally diverse tropolones from six subclasses to characterize their in vitro pharmacological parameters. All compounds were more soluble in pHs that reflect the gastrointestinal tract (pH 5 and 6.5) than plasma (pH 7.4). Those compounds that had solubility limits >100 μM were tested in a passive permeability assay, and there was no general trend in the compounds' passive permeability at any pH. Twenty-nine compounds with the best absorption parameters were tested in HEK293 cells to assess potential cytotoxicity; measured toxicities were similar to those in the hepatic HepDES19 cells used for screening (R2 = 0.55). Sixteen representative compounds were tested against five major CYP450 isoforms and there was no substantial inhibition by any compound against any of the enzymes tested (<50%). The t1/2 values of 15 compounds were determined in the microsome stability assay and 12 compounds were evaluated in plasma protein binding assays to assess factors affecting their rate of clearance. All compounds with detectable analyte peaks had t1/2 > 30 min, and while 4 of 12 had statistically significant decreased potency in conditions with increased albumin concentrations, only one compound's potency was biologically significant. These data indicate that the tropolones have pharmacological characteristics that reflect approved drugs and inform future structure activity relationships during drug design.

A High-Fat Diet Increases the Characteristics of Gut Microbial Composition and the Intestinal Damage Associated with Non-Alcoholic Fatty Liver Disease

The prevalence of non-alcoholic fatty liver disease (NAFLD) is increasing annually, and emerging evidence suggests that the gut microbiota plays a causative role in the development of NAFLD. However, the role of gut microbiota in the development of NAFLD remains unclear and warrants further investigation. Thus, C57BL/6J mice were fed a high-fat diet (HFD), and we found that the HFD significantly induced obesity and increased the accumulation of intrahepatic lipids, along with alterations in serum biochemical parameters. Moreover, it was observed that the HFD also impaired gut barrier integrity. It was revealed via 16S rRNA gene sequencing that the HFD increased gut microbial diversity, which enriched Colidextribacter, Lachnospiraceae-NK4A136-group, Acetatifactor, and Erysipelatoclostridium. Meanwhile, it reduced the abundance of Faecalibaculum, Muribaculaceae, and Coriobacteriaceae-UCG-002. The predicted metabolic pathways suggest that HFD enhances the chemotaxis and functional activity of gut microbiota pathways associated with flagellar assembly, while also increasing the risk of intestinal pathogen colonization and inflammation. And the phosphotransferase system, streptomycin biosynthesis, and starch/sucrose metabolism exhibited decreases. These findings reveal the composition and predictive functions of the intestinal microbiome in NAFLD, further corroborating the association between gut microbiota and NAFLD while providing novel insights into its potential application in gut microbiome research for NAFLD patients.

Efficacy and safety of tenofovir disoproxil fumarate versus entecavir in the treatment of acute-on-chronic liver failure with hepatitis B: a systematic review and meta-analysis

BACKGROUND

Oral nucleoside (acid) analogues (NAs) are recommended for patients with acute-on-chronic liver failure (ACLF) associated with hepatitis B virus (HBV-ACLF). The efficacy and safety of tenofovir (TDF) and entecavir (ETV) in these patients remain unclear.

METHODS

A comprehensive literature search in PubMed, Web of Science, The Cochrane Library, and Embase database was conducted to select studies published before December 2022 on TDF or ETV for HBV-ACLF. The primary outcomes were survival rates at 4, 12, and 48 weeks. Secondary outcomes were virologic and biochemical responses, serum antigen conversion, liver function score, and safety.

RESULTS

Four prospective and one retrospective cohort studies were selected. The overall analysis showed comparable survival rates at 4, 12, and 48 weeks for all patients receiving TDF or ETV (4-week: RR = 1.17, 95% CI: 0.90-1.51, p = 0.24; 12-week: RR = 1.00, 95% CI: 0.88-1.13, p = 0.94; 48-week: RR = 0.96, 95% CI: 0.58-1.57, p = 0.86). Child-Turcotte-Pugh (CTP) score and model for end-stage liver disease (MELD) score at 12 weeks were comparable in both groups but lower than baseline (CTP: SMD = -0.75, 95% CI:-2.81-1.30, p = 0.47; MELD: SMD = -1.10, 95% CI:-2.29-0.08, p = 0.07). At 48 weeks, estimated glomerular filtration rate (eGFR) levels were found to decrease to different degrees from baseline in both the TDF and ETV groups, and the decrease was greater in the TDF group than in the ETV group. No significant differences were found in biochemical, virologic response, and serum antigen conversion between the two groups during the observation period.

CONCLUSION

TDF treatment of HBV-ACLF is similar to ETV in improving survival, liver function, and virologic response but the effects on renal function in two groups in the long term remain unclear. More and larger long-term clinical trials are required to confirm these findings.

High Frequency of Antiviral Resistance Mutations in HBV Genotypes A2 and H: Multidrug Resistance Strains in Mexico

BACKGROUND AND AIMS

Lamivudine (3TC), telbivudine (LdT), entecavir (ETV), adefovir (ADF), and tenofovir (TFV) are drugs used to treat hepatitis B virus (HBV) infection, but specific mutations allow some viruses to become resistant to antiviral drugs or to acquire immune escape capacities. These mutations have not been thoroughly investigated in Mexico. This study aimed to estimate the prevalence of HBV antiviral resistance and escape mutations.

METHODS

This cross-sectional study analyzed 158 samples. HBV DNA was extracted, amplified, and sequenced in serum samples using the spin column method, PCR assay, and Sanger's sequencing, respectively. HBV genotypes were determined, and HBV mutations were tested using the Geno2pheno tool.

RESULTS

Overall, 68.4% (108/158) of HBV patients were infected with genotype H, followed by G (11.4%, 18/158), A2 (10.8%, 17/158), F1b (6.9.0%, 11/158), D (1.9%, 3/158), and E (0.6%, 1/158), and 5.1% (8/158) had evidence of recombination. The prevalence of resistance mutations was 8.2% (13/158) and the most common combined mutation was rt180M+rt204V. Notably, we found the combinations rt180M+rt204V+rt173L (n=2) and rt180M+rt204V+rt202G (n=1) that confer multidrug resistance to 3TC, LdT, and ETV. Resistance mutations were found in genotypes A2 (11.8%, 2/17), and H (10.2%, 11/108), and escape mutations were detected in HBV genotypes A2 (11.8%, 2/17), H (10.2%, 11/108), F1b (9.1%, 1/11) and G (5.6%, 1/18).

CONCLUSIONS

The highest prevalence of antiviral resistance mutations or escape mutations was detected in HBV genotypes A2 and H. The earliest cases of HBV multidrug resistance were detected in Mexico.

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

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

Structural insights into modeling of hepatitis B virus reverse transcriptase and identification of its inhibitors from potential medicinal plants of Western Ghats: an in silico and in vitro study

The present study was proposed to model full-length HBV-RT and investigate the intermolecular interactions of known inhibitor and libraries of phytocompounds to probe the potential natural leads by in silico and in vitro studies. Homology modeling of RT was performed by Phyre2 and Modeller and virtual screening of ligands implemented through POAP pipeline. Molecular dynamics (MD) simulation (100 ns) and MM-GBSA calculations were performed using Schrodinger Desmond and Prime, respectively. Phytocompounds probable host protein targets gene set pathway enrichment and network analysis were executed by KEGG database and Cytoscape software. Prioritized plant extracts/enriched fraction LC-MS analysis was performed and along with pure compound, RT inhibitory activity, time-dependent HBsAg and HBeAg secretion, and intracellular HBV DNA, and pgRNA by qRT-PCR was performed in HepG2.2.15 cell line. Among the screened chemical library of 268 phytocompounds from 18 medicinal plants, 15 molecules from Terminalia chebula (6), Bidens pilosa (5), and Centella asiatica (4)) were identified as potential inhibitors of YMDD and RT1 motif of HBV-RT. MD simulation demonstrated stable interactions of 15 phytocompounds with HBV-RT, of which 1,2,3,4,6-Pentagalloyl Glucose (PGG) was identified as lead molecule. Out of 15 compounds, 11 were predicted to modulate 39 proteins and 15 molecular pathways associated with HBV infection. TCN and TCW (500 µg/mL) showed potent RT inhibition, decreased intracellular HBV DNA, and pgRNA, and time-dependent inhibition of HBsAg and HBeAg levels compared to PGG and Tenofovir Disoproxil Fumarate. We propose that the identified lead molecules from T. chebula as promising and cost-effective moieties for the management of HBV infection.Communicated by Ramaswamy H. Sarma.

Antiviral Evaluation of Dispirotripiperazines against Hepatitis B Virus

Hepatitis B virus (HBV) is a hepatotropic DNA virus that replicates by reverse transcription. It chronically infects >296 million people worldwide, including ∼850,000 in the USA, and kills 820,000 annually worldwide. Current nucleos(t)ide analogue (NA) or pegylated interferon α therapies do not eradicate the virus and would benefit from a complementary antiviral drug. We performed a preliminary screen of 28 dispirotripiperazines against HBV, identifying 9 hits with EC50 of 0.7-25 μM. Compound 11826096 displays the most potent activity and represents a promising lead for future optimization. While the mechanism of action is unknown, preliminary assays limit possible targets to activities involved in RNA accumulation, translation, capsid assembly, and/or capsid stability. In addition, we built machine learning models to determine if they were able to predict the activity of this series of compounds. The novelty of these molecules indicated they were outside of the applicability domain of these models.

Hepatitis B Virus Epsilon (ε) RNA Element: Dynamic Regulator of Viral Replication and Attractive Therapeutic Target

Hepatitis B virus (HBV) chronically infects millions of people worldwide, which underscores the importance of discovering and designing novel anti-HBV therapeutics to complement current treatment strategies. An underexploited but attractive therapeutic target is ε, a cis-acting regulatory stem-loop RNA situated within the HBV pregenomic RNA (pgRNA). The binding of ε to the viral polymerase protein (P) is pivotal, as it triggers the packaging of pgRNA and P, as well as the reverse transcription of the viral genome. Consequently, small molecules capable of disrupting this interaction hold the potential to inhibit the early stages of HBV replication. The rational design of such ligands necessitates high-resolution structural information for the ε-P complex or its individual components. While these data are currently unavailable for P, our recent structural elucidation of ε through solution nuclear magnetic resonance spectroscopy marks a significant advancement in this area. In this review, we provide a brief overview of HBV replication and some of the therapeutic strategies to combat chronic HBV infection. These descriptions are intended to contextualize our recent experimental efforts to characterize ε and identify ε-targeting ligands, with the ultimate goal of developing novel anti-HBV therapeutics.

Chronic Hepatitis B Infection: New Approaches towards Cure

Chronic hepatitis B virus (HBV) infection leads to the development of cirrhosis and hepatocellular carcinoma. Lifelong treatment with nucleotides/nucleoside antiviral agents is effective at suppressing HBV replication, however, adherence to daily therapy can be challenging. This review discusses recent advances in the development of long-acting formulations for HBV treatment and prevention, which could potentially improve adherence. Promising new compounds that target distinct steps of the virus life cycle are summarized. In addition to treatments that suppress viral replication, curative strategies are focused on the elimination of covalently closed circular DNA and the inactivation of the integrated viral DNA from infected hepatocytes. We highlight promising long-acting antivirals and genome editing strategies for the elimination or deactivation of persistent viral DNA products in development.

Inhibition of Hepatitis B Virus (HBV) replication and antigen expression by Brucea javanica (L.) Merr. oil emulsion

Introduction

The seeds of Brucea javanica (L.) Merr. (BJ) have been traditionally used to treat various types of cancers for many years in China. In this study, we systematically investigated a BJ oil emulsion (BJOE) produced from BJ seeds with the purpose of evaluating its antiviral effect against hepatitis B virus (HBV).

Methods

HepG2.215 (a wild-type HBV cell line), HepG2, and Huh7, transfected with wildtype (WT) or lamivudine-resistance mutant (LMV-MT) HBV replicon plasmids, were treated with different doses of BJOE and then used for pharmacodynamic evaluation. Cell viability was determined using CCK8 assay. The levels of HBsAg/HBeAg in cell cultured supernatant, HBcAg in cell lysis solution, and HBV DNA in both were evaluated.

Results

BJOE at ≤5 mg/ml was nontoxic to carcinoma cell lines, but could significantly inhibit WT/LMV-MT HBV replication and HBs/e/c antigen expression in a dose-dependent manner by upregulating interleukin-6 (IL-6), demonstrating that it possesses moderate anti-HBV activity. As one of the major components of BJOE, bruceine B was found to play a dominant role in IL-6 induction and HBV inhibition.

Discussion

Our results demonstrated that BJOE suppressed HBV replication by stimulating IL-6, indicating that it has promising clinical therapeutic potential for both WT and LMV-MT HBV.

Synthetic gRNA/Cas9 ribonucleoprotein targeting HBV DNA inhibits viral replication

The presence of hepatitis B virus (HBV) covalently closed circular (ccc) DNA (cccDNA), which serves as a template for viral replication and integration of HBV DNA into the host cell genome, sustains liver pathogenesis and constitutes an intractable barrier to the eradication of chronic HBV infection. The current antiviral therapy for HBV infection, using nucleos(t)ide analogues (NAs), can suppress HBV replication but cannot eliminate integrated HBV DNA and episomal cccDNA. Clustered regularly interspaced short palindromic repeat (CRISPR)/Cas9 is a powerful genetic tool that can edit integrated HBV DNA and minichromosomal cccDNA for gene therapy, but its expression and delivery require a viral vector, which poses safety concerns for therapeutic applications in humans. In the present study, we used synthetic guide RNA (gRNA)/Cas9-ribonucleoprotein (RNP) as a nonviral formulation to develop a novel CRISPR/Cas9-mediated gene therapy for eradicating HBV infection. We designed a series of gRNAs targeting multiple specific HBV genes and tested their antiviral efficacy and cytotoxicity in different HBV cellular models. Transfection of stably HBV-infected human hepatoma cell line HepG2.2.15 with HBV-specific gRNA/Cas9 RNPs resulted in a substantial reduction in HBV transcripts. Specifically, gRNA5 and/or gRNA9 RNPs significantly reduced HBV cccDNA, total HBV DNA, pregenomic RNA, and HBV antigen (HBsAg, HBeAg) levels. T7 endonuclease 1 (T7E1) cleavage assay and DNA sequencing confirmed specific HBV gene cleavage and mutations at or around the gRNA target sites. Notably, this gene-editing system did not alter cellular viability or proliferation in the treated cells. Because of their rapid DNA cleavage capability, low off-target effects, low risk of insertional mutagenesis, and readiness for use in clinical application, these results suggest that synthetic gRNA/Cas9 RNP-based gene-editing can be utilized as a promising therapeutic drug for eradicating chronic HBV infection.

Viral sequence analysis of chronic hepatitis B patients treated with the capsid assembly modulator JNJ-56136379 in the JADE phase 2a study

BACKGROUND & AIMS

In the monotherapy arms of the phase 2 JADE study (ClinicalTrials.gov Identifier: NCT03361956) evaluating the safety and efficacy of JNJ-56136379 (capsid assembly modulator-class E) with/without nucleos(t)ide analogue (NA), viral breakthroughs (VBT) were observed, leading to JNJ-56136379 monotherapy discontinuation. We present the viral sequencing analysis of JNJ-56136379±NA-treated hepatitis B virus (HBV)-infected patients.

METHODS

The HBV full genome was sequenced using next generation sequencing. Baseline amino acid (aa) polymorphisms were defined as changes versus the universal HBV reference sequence (sequence read frequency >15%). Emerging mutations were defined as aa changes versus baseline sequence (frequency <1% at baseline and ≥15% post-baseline).

RESULTS

6/28 JNJ-56136379 75 mg monotherapy arm patients experienced VBT; all 6 had emerging JNJ-56136379-resistant variants T33N (n = 5; fold change [FC] = 85) or F23Y (n = 1; FC = 5.2). 1/32 JNJ-56136379 250 mg arm patients (genotype-E) had <1 log₁₀ IU/mL decline in HBV DNA at Week 4, experienced VBT at Week 8, and carried the I105T baseline polymorphism (FC = 7.9), but had no emerging variants. Eight additional monotherapy-treated patients had shallow second phases of their HBV DNA profile and emerging T33N (n = 7) or F23Y (n = 1) variants. NA initiation (switch [75 mg arm]; add-on [250 mg arm]) in all monotherapy patients with VBT resulted in HBV DNA decline in all patients. No VBT was observed during JNJ-56136379+NA combination therapy.

CONCLUSIONS

JNJ-56136379 monotherapy resulted in VBT and was associated with the selection of JNJ-56136379-resistant variants. Efficacy of NA treatment (de novo combination or rescue therapy for VBT) was not impacted, confirming the lack of cross-resistance between these drug classes.

CLINICAL TRIAL NUMBER

NCT03361956.

Evidence of Residual Ongoing Viral Replication in Chronic Hepatitis B Patients Successfully Treated With Nucleos(t)ide Analogues

BACKGROUND

Chronic hepatitis B is usually treated with nucleos(t)ide analogues (NAs). However, a cure is rarely achieved, even with years of treatment. Here, we investigated whether viral replication is completely halted and how long covalently closed circular DNA (cccDNA) persists in patients successfully treated with NAs.

METHODS

A series of longitudinal serum samples and a collection of cross-sectional liver biopsies were obtained from patients successfully treated with NAs. Viral variants in serum HBV RNA were enumerated by deep sequencing. Viral replication intermediates in hepatocytes were directly visualized by in situ hybridization. The apparent half-life of each cccDNA was estimated.

RESULTS

Three of 6 successfully treated patients demonstrated clear evidence of a small proportion of virus evolution, although the overwhelming proportion of variants were identical or possessed a similar degree of divergence through time. The apparent half-life of variants was estimated to be from approximately 7.42 weeks to infinite. Hepatocytes remained positive for cytoplasmic nucleocapsids-associated relaxed circular DNA in 4 of 7 liver needle biopsies.

CONCLUSIONS

We conclude that even after prolonged treatment, a small proportion of the cccDNA reservoir is constantly replenished by continued low-level HBV replication, whereas a large proportion of the cccDNA reservoir persists over time.

Virtual Screening of Hepatitis B Virus Pre-Genomic RNA as a Novel Therapeutic Target

The global burden imposed by hepatitis B virus (HBV) infection necessitates the discovery and design of novel antiviral drugs to complement existing treatments. One attractive and underexploited therapeutic target is ε, an ~85-nucleotide (nt) cis-acting regulatory stem-loop RNA located at the 3'- and 5'-ends of the pre-genomic RNA (pgRNA). Binding of the 5'-end ε to the viral polymerase protein (P) triggers two early events in HBV replication: pgRNA and P packaging and reverse transcription. Our recent solution nuclear magnetic resonance spectroscopy structure of ε permits structure-informed drug discovery efforts that are currently lacking for P. Here, we employ a virtual screen against ε using a Food and Drug Administration (FDA)-approved compound library, followed by in vitro binding assays. This approach revealed that the anti-hepatitis C virus drug Daclatasvir is a selective ε-targeting ligand. Additional molecular dynamics simulations demonstrated that Daclatasvir targets ε at its flexible 6-nt priming loop (PL) bulge and modulates its dynamics. Given the functional importance of the PL, our work supports the notion that targeting ε dynamics may be an effective anti-HBV therapeutic strategy.

Molecular and Genetic Characterization of Hepatitis B Virus (HBV) among Saudi Chronically HBV-Infected Individuals

The study aimed to characterize the genotype and subgenotypes of HBV circulating in Saudi Arabia, the presence of clinically relevant mutations possibly associated with resistance to antivirals or immune escape phenomena, and the possible impact of mutations in the structural characteristics of HBV polymerase. Plasma samples from 12 Saudi Arabian HBV-infected patients were analyzed using an in-house PCR method and direct sequencing. Saudi patients were infected with mainly subgenotype D1. A number of mutations in the RT gene (correlated to antiviral resistance) and within and outside the major hydrophilic region of the S gene (claimed to influence immunogenicity and be related to immune escape) were observed in almost all patients. Furthermore, the presence of mutations in the S region caused a change in the tertiary structure of the protein compared with the consensus region. Clinical manifestations of HBV infection may change dramatically as a result of viral and host factors: the study of mutations and protein-associated cofactors might define possible aspects relevant for the natural and therapeutic history of HBV infection.

Recent trends and advancements in electrochemiluminescence biosensors for human virus detection

Researchers are constantly looking to find new techniques of virus detection that are sensitive, cost-effective, and accurate. Additionally, they can be used as a point-of-care (POC) tool due to the fact that the populace is growing at a quick tempo, and epidemics are materializing greater often than ever. Electrochemiluminescence-based (ECL) biosensors for the detection of viruses have become one of the most quickly developing sensors in this field. Thus, we here focus on recent trends and developments of these sensors with regard to virus detection. Also, quantitative analysis of various viruses (e.g., Influenza virus, SARS-CoV-2, HIV, HPV, Hepatitis virus, and Zika virus) with a specific interest in Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) was introduced from the perspective of the biomarker and the biological receptor immobilized on the ECL-based sensors, such as nucleic acids-based, immunosensors, and other affinity ECL biosensors.

Safety and efficacy of vebicorvir administered with entecavir in treatment-naïve patients with chronic hepatitis B virus infection

BACKGROUND & AIMS

Nucleos(t)ide reverse transcriptase inhibitors do not completely suppress HBV DNA in chronic HBV infection (cHBV). Vebicorvir (VBR) is an investigational core inhibitor that interferes with multiple aspects of HBV replication. This phase II trial evaluated the safety and efficacy of VBR in combination with entecavir (ETV) in treatment-naïve patients with cHBV.

METHODS

HBeAg-positive, treatment-naïve patients without cirrhosis were randomised 1:1 in a double-blind manner to once-daily VBR 300 mg+ETV 0.5 mg or placebo (PBO)+ETV 0.5 mg for 24 weeks. The primary endpoint was change in mean log10 HBV DNA from Baseline to Week 12 and 24.

RESULTS

All patients in both treatment groups (PBO+ETV: 12/12; VBR+ETV: 13/13) completed the study. At Week 12, VBR+ETV led to a greater mean (SD) reduction from Baseline in log10 IU/ml HBV DNA (-4.45 [1.03]) vs. PBO+ETV (-3.30 [1.18]; p = 0.0077). At Week 24, VBR+ETV led to a greater reduction from Baseline in log10 IU/ml HBV DNA (-5.33 [1.59]) vs. PBO+ETV (-4.20 [0.98]; p = 0.0084). Greater mean reductions in pregenomic RNA were observed at Week 12 and 24 in patients receiving VBR+ETV vs. PBO+ETV (p <0.0001 and p <0.0001). Changes in viral antigens were similar in both groups. No drug interaction between VBR and ETV was observed. Two patients experienced HBV DNA rebound during treatment, with no resistance breakthrough detected. The safety of VBR+ETV was similar to PBO+ETV. All treatment-emergent adverse events and laboratory abnormalities were Grade 1/2. There were no deaths, serious adverse events, or evidence of drug-induced liver injury.

CONCLUSIONS

In this 24-week study, VBR+ETV provided additive antiviral activity over PBO+ETV in treatment-naïve patients with cHBV, with a favourable safety and tolerability profile.

CLINICAL TRIAL NUMBER

NCT03577171 LAY SUMMARY: Hepatitis B is a long-lasting viral infection of the liver. Current treatments can suppress hepatitis B virus but do not offer the opportunity of cure, hence, new treatment approaches are required. Herein, we show that the combination of the novel core inhibitor vebicorvir with an existing antiviral (entecavir) in treatment-naïve patients chronically infected with hepatitis B virus demonstrated greater antiviral activity than entecavir alone. Additionally, vebicorvir was safe and well tolerated. Thus, further studies evaluating its potential role in the treatment of chronic hepatitis B are warranted.

Towards a Functional Cure for Hepatitis B Virus: A 2022 Update on New Antiviral Strategies

Chronic infection with hepatitis B virus (HBV) represents one of the main causes of the development of cirrhosis and its complications. Treatment with potent third-generation nucleos(t)ide analogues (NUCs) results in >99% HBV DNA undetectability, and prevents fibrosis progression and liver-related complications. However, NUCs are not able to induce the so-called functional cure, which is hepatitis B surface antigen (HBsAg) loss and anti-HBs seroconversion. Consequently, NUC treatment is currently intended as being long-term or lifelong, resulting in the need for clinical monitoring and potentially suffering from compliance issues. Consequently, drug development in HBV has the goal of developing new agents in order to achieve a functional cure for HBV. Currently, the three main strategies include the following: inhibition of viral replication, inhibition of viral antigens, and immune modulation. This review summarizes the most recent updates concerning HBV compounds among these three main classes.

Susceptibility of Drug Resistant Hepatitis B Virus Mutants to Besifovir

Currently, interferon alpha and nucleos(t)ide analogues (NAs) are clinically available to treat hepatitis B virus (HBV) infection. Several NAs, including lamivudine (LMV), adefovir (ADV), entecavir (ETV) and tenofovir (TDF or TAF) have been approved and administered to chronic hepatitis B (CHB) patients. NAs inhibit HBV DNA synthesis by targeting the reverse transcriptase (RT) domain of HBV polymerase. Several mutations in the RT domain which lead to drug resistance against NAs have been reported, even for TDF and TAF which are highly potent with very low resistance rate. Besifovir (BFV) is a new antiviral dGMP analogue able to be used as a new NA drug for the control of CHB infection. Drug resistance to BFV is not well known due to its shorter duration of clinical use. Recently, we reported that rtL180M (M) and rtM204V (V) mutations, already resistant to LMV, are associated with BFV resistance. However, the susceptibility to BFV of previously known HBV mutants resistant to various drugs has not been studied. To investigate this, we performed in vitro drug susceptibility assays using natural and artificial mutants that are associated with resistance to LMV, ADV, ETV or TDF. As a result, LMV-resistant mutants were not susceptible to BFV and ETV-resistant clones showed partial resistance against BFV as well. However, ADV-resistant mutants were highly sensitive to BFV. In case of tenofovir-resistant mutations, the HBV mutants harboring primary mutations to tenofovir resistance were susceptible to BFV. Therefore, our study revealed that BSV may serve as an alternative drug for patients with ADV-, ETV-, TDF- or TAF-resistance.

From HIV to COVID-19, Molecular mechanisms of pathogens' trade-off and persistence in the community, potential targets for new drug development

BACKGROUND

On the staggering emergence of the Omicron variant, numerous questions arose about the evolution of virulence and transmissibility in microbes.

MAIN BODY OF THE ABSTRACT

The trade-off hypothesis has long speculated the exchange of virulence for the sake of superior transmissibility in a wide array of pathogens. While this certainly applies to the case of the Omicron variant, along with influenza virus, various reports have been allocated for an array of pathogens such as human immunodeficiency virus (HIV), malaria, hepatitis B virus (HBV) and tuberculosis (TB). The latter abide to another form of trade-off, the invasion-persistence trade-off. In this study, we aim to explore the molecular mechanisms and mutations of different obligate intracellular pathogens that attenuated their more morbid characters, virulence in acute infections and invasion in chronic infections.

SHORT CONCLUSION

Recognizing the mutations that attenuate the most morbid characters of pathogens such as virulence or persistence can help in tailoring new therapies for such pathogens. Targeting macrophage tropism of HIV by carbohydrate-binding agents, or targeting the TMPRSS2 receptors to prevent pulmonary infiltrates of COVID-19 is an example of how important is to recognize such genetic mechanisms.

Persistent Hepatitis B Viraemia with Polymerase Mutations among HIV/HBV Co-Infected Patients on HBV-Active ART in KwaZulu-Natal, South Africa

To understand the problem of persistent Hepatitis B virus (HBV) viraemia in HIV/HBV co-infected patients on HBV-active antiretroviral therapy (ART), we assessed the rate of HBV virological response in patients on HBV-active ART in KwaZulu-Natal, South Africa, and analysed factors associated with persistent HBV viraemia. One hundred and fifty eligible participants with a chronic HBV diagnosis, with or without HIV coinfection, were enrolled and followed up after 6 months. The HBV pol gene was sequenced by next-generation sequencing and mutations were determined using the Stanford HBVseq database. Logistic regression analysis was used to assess factors associated with HBV viraemia at 6-month follow-up. The mean duration of HBV-active ART was 24 months. Thirty-seven of one hundred and six (35%) participants receiving HBV-active ART for longer than 6 months had virological failure. Advanced immunosuppression with CD4+ cell counts <200 cells/μL was independently associated with persistent HBV viraemia, aOR 5.276 (95% CI 1.575−17.670) p = 0.007. A high proportion of patients on HBV-active ART are unsuppressed, which will ultimately have an impact on global elimination goals. Better monitoring should be implemented, especially in HIV-coinfected patients with low CD4+ cell counts and followed by early HBV drug-resistance testing.

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

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

Translational Strategies to Eliminate Chronic Hepatitis B in Children: Prophylaxis and Management in East Asian Countries

Translational medical research on hepatitis B virus (HBV) infection and chronic hepatitis B (CHB) pathogenesis provides guidance on strengthening the treatment and prevention strategies of CHB. Preventing vertical transmission is the key to eliminating HBV infection in children. The understanding of HBV replication, hepatocyte turnover, and the fate of covalently closed circular DNA (cccDNA) would help establish a personalized application of the guidelines, especially concerning the discontinuation of nucleos(t)ide analog (NA) treatment in children. Transplacental leakage of HBV-infected maternal blood is suggested as the leading cause of vertical transmission. Prenatal maternal prophylaxis could diminish maternal HBV viremia at delivery, to reduce the risk of neonatal HBV infection. The meaning of the expression "no additional risk of breast milk feeding" is thereby explained. Understanding the untreated natural course of CHB in children and the course changeable by treatment is important to apply individualistic strategies and avoid the immoral selection of treatment indications. NAs with potent efficacy and a high barrier to drug resistance should be used as first-line treatment to reduce the likelihood of NA-resistant HBV development because the rate of mutant HBV emergence might count on the infected hepatocyte turnover rate in chronic HBV infection. Although elimination of intranuclear cccDNA is difficult by NAs alone, a cure is possible by human immunity and hepatocyte turnover. The reduction of intranuclear cccDNA occurs after the destruction of HBV-infected hepatocytes, non-cytolytic immune response, apoptosis of hepatocytes, and compensatory cell proliferation. Therefore, consolidation therapy after NA-induced hepatitis B e-antigen seroconversion must be necessary for a sufficient period. This review also summarizes the treatment strategies of CHB in children based on the practical application of translational research.

Viral hepatitis in 2021: The challenges remaining and how we should tackle them

Viral hepatitis results in 1.4 million deaths annually. The World Health Organization (WHO) set an ambitious target to eliminate viral hepatitis by 2030, but significant challenges remain. These include inequalities in access to healthcare, reaching at risk populations and providing access to screening and effective treatment. Stigma around viral hepatitis persists and must be addressed. The WHO goal of global elimination by 2030 is a worthy aim, but remains ambitious and the coronavirus 2019 pandemic undoubtedly has set back progress. This review article will focus on hepatitis A to E, highlighting problems that have been resolved in the field over the past decade, those that remain to be resolved and suggest directions for future problem solving and research.

Blocking neddylation elicits antiviral effect against hepatitis B virus replication

BACKGROUND

Hepatitis B Virus (HBV) is the most common cause of chronic liver disease worldwide. The mechanisms that regulate HBV viral replication remain poorly defined. Here, we show that blocking of the neddylation elicits antiviral effect against HBV replication, indicating that NEDD8 supports viral production.

METHODS AND RESULTS

To explore role of neddylation, HBV-replicating HepG2.2.15.7 cells and HBV-infected HepG2-hNTCP-30 cells were treated with siNEDD8 and MLN4924, a potent and selective NEDD8-activating enzyme inhibitor. Cell viability, intracellular and extracellular HBV DNA, covalently closed circular DNA (cccDNA), HBsAg, HBeAg, and HBcrAg were measured to assess the consequences of the various treatments on viral replication. Our data showed that HBV infection increased NEDD8 expression in human liver cell lines. Symmetrically, NEDD8 knockdown by siRNA or MLN4924 treatments decreased HBV replication in HepG2.2.15.7 and HepG2-hNTCP-30 cells. Notably, HBsAg, and HBeAg secretions were strongly suppressed in the culture supernatants, but not the HBcrAg. These results indicate that the suppression of NEDD8 decreases HBV replication. However, cccDNA steady level confirms once again its persistence and longevity in chronic infection.

CONCLUSION

The manipulation of the neddylation pathway can thus provide new tools interfering with HBV persistence as well as novel therapeutic strategies against chronic hepatitis B.

Should We Treat Immune Tolerant Chronic Hepatitis B? Lessons from Asia

BACKGROUND

Chronic hepatitis B (CHB) remains a public health burden, with more than 257 million persons living with hepatitis B virus globally. Despite the availability of a safe and efficacious vaccine, access to immunization remains poor. As per current estimates, if Asian countries rely only on immunization to reduce the burden of disease, the timelines for HBV elimination will be extended to 2060-2090, a far cry from the World Health Organization's clarion call for viral hepatitis elimination by 2030.

METHODS

Currently, all practice guidelines lay stress on immunization, prevention of mother-to-child transmission and treatment of immune active disease or cirrhosis. In this review, we critically examine the data from the Asian cohorts, clinical and public health rationale of early treatment, risk of HCC, and assess the need for revision of guidelines.

DISCUSSION

Patients in the immune tolerant phase (IT) remain untreated till they meet variable age, transaminase, or fibrosis criteria, are often lost to follow up and continue transmitting the infection. With global migration patterns, immunization programmes alone cannot prevent the complications of HBV like cirrhosis, end-stage liver disease, and hepatocellular carcinoma (HCC). In addition, data from Asian cohorts from Taiwan and Korea suggest that HBV DNA levels are directly associated with increased risk of HCC. Histological evidence of advanced fibrosis or immune reactive T cell subsets in the IT phase also raises doubts about the viability of current guidelines that focus on age, alanine transaminase levels, and liver stiffness as markers of risk of inflammation and fibrosis. Current practice does not take into account the histological subsets with minimal inflammation, HBV genome integration or risk of HCC with high viral loads.

CONCLUSION

New data from Asian cohorts argue the case of expanding access to care to IT-CHB from public health and clinical perspective.

The hepatitis B virus polymerase

Hepatitis B virus (HBV) is a hepatotropic, partially double-stranded DNA virus that replicates by reverse transcription and is a major cause of chronic liver disease and hepatocellular carcinoma. Reverse transcription is catalyzed by the four-domain multifunctional HBV polymerase (P) protein that has protein-priming, RNA- and DNA-dependent DNA synthesis (i.e., reverse transcriptase), and ribonuclease H activities. P also likely promotes the three strand transfers that occur during reverse transcription, and it may participate in immune evasion by HBV. Reverse transcription is primed by a tyrosine residue in the amino-terminal domain of P, and P remains covalently attached to the product DNA throughout reverse transcription. The reverse transcriptase activity of P is the target for the nucleos(t)ide analog drugs that dominate HBV treatment, and P is the target of ongoing efforts to develop new drugs against both the reverse transcriptase and ribonuclease H activities. Despite the unusual reverse transcription pathway catalyzed by P and the importance of P to HBV therapy, understanding the enzymology and structure of HBV P severely lags that of the retroviral reverse transcriptases due to substantial technical challenges to studying the enzyme. Obtaining a better understanding of P will broaden our appreciation of the diversity among reverse transcribing elements in nature, and will help improve treatment for people chronically infected with HBV.

A nuanced role of the small loop of hepatitis B virus small envelope protein in virion morphogenesis and secretion

BACKGROUND

The virion secretion mechanism of human hepatitis B virus (HBV) remains to be investigated. In our current study, we characterized a reverse transcriptase mutant, which changed from the YMDD motif to YMHA. We noted that this mutant YMHA secreted no virions in the medium. Because of the overlapping open reading frame (ORF) between the polymerase and the envelope genes, the lack of virion secretion is likely due to corresponding concurrent mutations in a small loop of the envelope protein (HBsAg, HBV surface antigen). In literature, small loop mutations are thought to affect virion secretion of hepatitis delta virus (HDV), but not HBV.

METHODS

Here, we revisited the relationship between the small loop and virion secretion by site-directed mutagenesis and native agarose gel electrophoresis.

RESULTS

A proline substitution at residue 196 or 198 in the small loop blocked both HBV genome-containing and genome-free virion secretion, but not the secretion of 22-nm HBsAg subviral particles. Surprisingly, a leucine substitution at residue 196 enhanced genome-containing virion secretion. It is also intriguing that a proline-197, sandwiched by residue 196 and 198, exhibited no apparent defect in secreted virions, with or without containing an HBV genome. By complementation assay, we demonstrated that the wild type small envelope protein alone is sufficient to rescue the virion secretion defect of a small loop mutant M198P.

CONCLUSIONS

The effect of the small loop mutation of HBV small envelope protein on virion secretion is position-dependent. It warrants further investigation how the small loop of HBsAg plays a subtle role in HBV morphogenesis and secretion of virions with or without containing an HBV genome.

Efficient Inhibition of Hepatitis B Virus (HBV) Replication and cccDNA Formation by HBV Ribonuclease H Inhibitors during Infection

The hepatitis B virus (HBV) ribonuclease H (RNase H) is an attractive but unexploited drug target. Here, we addressed three limitations to the current state of RNase H inhibitor development: (a) Efficacy has been assessed only in transfected cell lines. (b) Cytotoxicity data are from transformed cell lines rather than primary cells. (c) It is unknown how the compounds work against nucleos(t)ide analog resistant HBV strains. Three RNase H inhibitors from different chemotypes, 110 (α-hydroxytropolone), 1133 (N-hydroxypyridinedione), and 1073 (N-hydroxynapthyridinone), were tested in HBV-infected HepG2-NTCP cells for inhibition of cccDNA accumulation and HBV product formation. 50% effective concentrations (EC₅₀s) were 0.049-0.078 μM in the infection studies compared to 0.29-1.6 μM in transfected cells. All compounds suppressed cccDNA formation by >98% at 5 μM when added shortly after infection. HBV RNA, intracellular and extracellular DNA, and HBsAg secretion were all robustly suppressed. The greater efficacy of the inhibitors when added shortly after infection is presumably due to blocking amplification of the HBV cccDNA, which suppresses events downstream of cccDNA formation. The compounds had 50% cytotoxic concentrations (CC₅₀s) of 16-100 μM in HepG2-derived cell lines but were nontoxic in primary human hepatocytes, possibly due to the quiescent state of the hepatocytes. The compounds had similar EC₅₀s against replication of wild-type, lamivudine-resistant, and adefovir/lamivudine-resistant HBV, as expected because the RNase H inhibitors do not target the viral reverse transcriptase active site. These studies expand confidence in inhibiting the HBV RNase H as a drug strategy and support inclusion of RNase H inhibitors in novel curative drug combinations for HBV.

Effectiveness of tenofovir alafenamide for chronic hepatitis B patients with a poor response to the previously used nucleos(t)ide analogs

BACKGROUND

Few studies have demonstrated the potency of tenofovir alafenamide (TAF) in patients with poor response to other nucleos(t)ide analogs (NAs).

METHODS

We conducted a retrospective study comprising consecutive 40 patients exhibiting a poor response to other NAs, who subsequently received TAF-containing regimens. The primary outcome was the prevalence of virological response (VR) at each time and maintained virological response (MVR) under TAF-containing regimens until week 96.

RESULTS

In the entire cohort, the prevalence of MVR was 71.1% (27/38). Further, poor tenofovir disoproxil fumarate (TDF) response was significantly associated with a lower prevalence of MVR (p = 0.014). In TDF-naïve patients, the prevalence of MVR was 92.3% (12/13) and 62.5% (5/8) in patients with lamivudine resistance (LAM-r) and entecavir resistance (ETV-r), respectively. Further, viral load and HBeAg status at baseline were associated with a lower prevalence of MVR (p = 0.013). Among the seven patients with prior TDF exposure, 2 patients achieved MVR. Among them, one patient with development of viral breakthrough during TDF/LAM achieved MVR after switching to TAF/ETV. In contrast, one of the five patients with non-MVR had three substitutions (rtS106C, rtD134N/S, and rtL269I) of quadruple mutations in addition to ETV-r. Other patients with rtA181T + rtN236T also could not achieve MVR.

CONCLUSION

TAF exhibited high antiviral potency in patients with LAM-r and ETV-r. However, TAF potency was associated with previous TDF response, viral load, and HBeAg status at baseline. Additionally, a quadruple mutation may impact tenofovir resistance; however, further studies are needed to verify this.

The Hepatitis B Virus Nucleocapsid-Dynamic Compartment for Infectious Virus Production and New Antiviral Target

Hepatitis B virus (HBV) is a small enveloped DNA virus which replicates its tiny 3.2 kb genome by reverse transcription inside an icosahedral nucleocapsid, formed by a single ~180 amino acid capsid, or core, protein (Cp). HBV causes chronic hepatitis B (CHB), a severe liver disease responsible for nearly a million deaths each year. Most of HBV's only seven primary gene products are multifunctional. Though less obvious than for the multi-domain polymerase, P protein, this is equally crucial for Cp with its multiple roles in the viral life-cycle. Cp provides a stable genome container during extracellular phases, allows for directed intracellular genome transport and timely release from the capsid, and subsequent assembly of new nucleocapsids around P protein and the pregenomic (pg) RNA, forming a distinct compartment for reverse transcription. These opposing features are enabled by dynamic post-transcriptional modifications of Cp which result in dynamic structural alterations. Their perturbation by capsid assembly modulators (CAMs) is a promising new antiviral concept. CAMs inappropriately accelerate assembly and/or distort the capsid shell. We summarize the functional, biochemical, and structural dynamics of Cp, and discuss the therapeutic potential of CAMs based on clinical data. Presently, CAMs appear as a valuable addition but not a substitute for existing therapies. However, as part of rational combination therapies CAMs may bring the ambitious goal of a cure for CHB closer to reality.

Quercetin and its derivates as antiviral potentials: A comprehensive review

Quercetin, widely distributed in fruits and vegetables, is a flavonoid known for its antioxidant, antiviral, antimicrobial, and antiinflammatory properties. Several studies highlight the potential use of quercetin as an antiviral, due to its ability to inhibit the initial stages of virus infection, to be able to interact with proteases important for viral replication, and to reduce inflammation caused by infection. Quercetin could also be useful in combination with other drugs to potentially enhance the effects or synergistically interact with them, in order to reduce their side effects and related toxicity. Since there is no comprehensive compilation about antiviral activities of quercetin and derivates, the aim of this review is providing a summary of their antiviral activities on a set of human viral infections along with mechanisms of action. Thus, the following family of viruses are examined: Flaviviridae, Herpesviridae, Orthomyxoviridae, Coronaviridae, Hepadnaviridae, Retroviridae, Picornaviridae, Pneumoviridae, and Filoviridae.

Clinical Features and Resistance to Entecavir Monotherapy of Patients with Hepatitis B

AIM

Hepatitis B virus (HBV) infection is a major public health concern worldwide. Entecavir (ETV), a first-line nucleos(t)ide analogue (NA) for HBV, has a low risk of resistance. We evaluated the efficacy of ETV monotherapy, ratio of ETV-resistant, and the clinical features of patients with ETV resistance.

METHODS

A total of 130 patients (72 males, 58 females; mean age, 61 ± 15 years) were divided into a NA-naïve group (n = 108) and NA-experienced group (n = 22). We examined the clinical outcomes of ETV monotherapy and associated factors. We also assessed the clinical features of 15 patients with resistance to ETV (mean, 51.0 ± 27.4 weeks).

RESULTS

Among the 130 patients, 94.1% achieved ALT normalization and 63.6% achieved serum HBV DNA negativity after ETV monotherapy for 96 weeks. Of the patients in the NA-naïve group, 93.1% and 60.4% achieved ALT normalization and HBV DNA negativity, respectively. Of the patients in the NA-experienced group, 100% and 74.9% achieved ALT normalization and HBV DNA negativity, respectively. Compared to patients on ETV continuously, 15 ETV-resistant patients had a higher baseline HBV viral load. There was a significant difference in the time to HBV DNA negativity, but not ALT normalization after ETV monotherapy in these groups. Rescue treatment with other NAs led to ALT normalization in all of these patients, but not HBV DNA negativity.

CONCLUSIONS

ETV monotherapy has a long-term clinical efficacy. While some patients especially with HBV DNA high viral load developed ETV resistance, rescue treatment led to ALT normalization in these patients.