Chronic hepatitis B virus (HBV) infection affects nearly 300 million people worldwide and remains a leading cause of liver cirrhosis and hepatocellular carcinoma. Although current therapies, including interferon-α and nucleos(t)ide analogs, can suppress viral replication, they rarely achieve a functional or sterilizing cure, largely due to the persistence of covalently closed circular DNA (cccDNA) and profound immune dysfunction. Accumulating evidence indicates that noncytopathic immune mechanisms, particularly those mediated by interferons (IFNs) and inflammatory cytokines, are important to viral control. Interferon-stimulated genes (ISGs) and the nuclear factor-κB (NF-κB) signaling pathway together orchestrate a broad antiviral and immunomodulatory network that targets multiple stages of the HBV life cycle while shaping innate and adaptive immune responses. In this review, we comprehensively summarize current knowledge on how ISGs and NF-κB signaling restrict the life cycle of HBV infection. We further discuss the immunomodulatory roles of these pathways in reinforcing innate immune sensing, cytokine production, macrophage polarization, and T cell differentiation and function, all of which are critical determinants of HBV persistence versus clearance. Finally, we review emerging immunomodulatory strategies under preclinical and clinical development that exploit ISGs, pattern-recognition receptors, and NF-κB related pathways, and highlight the challenges and opportunities in translating these insights into curative therapies. Collectively, this review underscores the central role of ISGs and NF-κB signaling as both antiviral effectors and therapeutic targets, providing a conceptual framework for the development of next-generation immunotherapies aimed at curing chronic HBV infection.

Background Plasmablast-derived HBV surface antigen (HBsAg)-specific monoclonal antibody (mAb) and structural basis for binding to native HBsAg are poorly known.Objective We aimed to identify plasmablast-derived HBsAg-specific mAbs, evaluate their antiviral activities and resolve their structure for binding to native HBsAg.Design A previously vaccinated volunteer was enrolled in this study, who was boosted with a dose of recombinant hepatitis B vaccine and donated the blood sample. Activated plasmablasts were sorted from fresh peripheral blood mononuclear cells and mAbs were expressed. Their gene features, cross-genotypic binding activities and antiviral functions in vitro and in vivo were comprehensively analysed. The cryo-electron microscopy (cryo-EM) was used to determine the structure of representative mAb bound to the native HBsAg.Results In this study, we cloned a series of HBsAg-specific mAbs directly from clonally expanded plasmablasts from a vaccinated individual. Most of the mAbs displayed cross-reactivities of binding to different genotype HBsAg proteins and antiviral functions such as neutralisation and antibody-dependent cellular phagocytosis. These human anti-HBsAg mAbs, especially SY-4-class and SY-23-class, could be good candidates for antibody drugs. The cryo-EM structure of SY-23 bound to the dimeric HBsAg was determined, revealing its binding mechanism and unprecedented structural detail of the major antigenic loop (AGL) of HBsAg.Conclusion Overall, our work has uncovered the diverse gene features and varied anti-HBV activities of plasmablast-derived mAbs, providing a series of antibody drug candidates and the long-sought-after atomic model of AGL has paved the way for a wholistic characterisation of the AGL's dynamic conformation during HBV infection and immune response.

Nuclear export of viral RNAs is essential for the replication of hepatitis B virus (HBV). Our previous study demonstrated that ELAVL1 (embryonic lethal, abnormal vision, Drosophila-like 1) mediates the nuclear export of HBV RNAs via the chromosome region maintenance 1 (CRM1) pathway by recognizing and binding to the AUUUA motifs within these transcripts. Here, we identify Ras-related nuclear protein (RAN) and RAN-binding protein 3 (RANBP3) as critical downstream regulators of this CRM1-mediated RNA export pathway. We show that RANBP3 recruits RAN-GTP to assemble an export-competent quaternary complex (CRM1-HBV RNAs-RANBP3-RAN-GTP). The functional significance of this complex is underscored by the findings that its disruption, through knockdown of RANBP3/RAN, or by introducing CRM1 mutations that prevent cofactor binding, severely impairs HBV RNA export and viral replication. Together, our study thus elucidates a precise regulatory mechanism governing HBV RNA trafficking and highlights RANBP3 and RAN as potential antiviral targets.IMPORTANCEEfficient nuclear export of hepatitis B virus (HBV) RNAs is essential for viral replication, yet the regulatory mechanisms controlling this process remain poorly defined. This study identifies Ras-related nuclear protein (RAN) and RAN-binding protein 3 (RANBP3) as key host cofactors that drive chromosome region maintenance 1 (CRM1)-mediated export of HBV transcripts by assembling an export-competent complex with viral RNAs. Disrupting this pathway profoundly impairs RNA export and downstream steps of the viral life cycle. By defining how HBV harnesses the RANBP3-RAN-CRM1 axis for RNA trafficking, our work reveals a previously unrecognized layer of host dependency and highlights RANBP3 and RAN as promising targets for antiviral intervention.

Hepatitis B virus (HBV) remains a major global public health challenge. Current therapeutic strategies against HBV have limited efficacy, primarily due to the persistence of covalently closed circular DNA (cccDNA) that resists eradication. Family with sequence similarity 151 member A (FAM151A), a member of the FAM151 protein family, is poorly characterized, and its potential antiviral effects have not been previously investigated. In this study, three experimental models were employed to evaluate the antiviral effects of FAM151A, including the HBV1.3 plasmid transfection cell model, AAV1.2-HBV mouse model, and HBV-infected cell culture systems. HBV replication markers were measured to determine which replication stage was affected by FAM151A. Luciferase reporter assays and Chromatin immunoprecipitation were employed to investigate the effects on HBV covalently closed circular DNA (cccDNA). As a result, in both in vivo and in vitro models, FAM151A inhibited HBV replication. Results from in vitro experiments showed that FAM151A inhibited cccDNA transcriptional activity without altering its abundance. Mechanistically, FAM151A regulates HBV promoter activity through post-transcriptional modifications of cccDNA and regulation of host transcription factors involved in HBV RNA synthesis. Overall, this study reveals a previously unrecognized role of FAM151A in modulating cccDNA transcriptional activity. These findings provide important insights into the role of FAM151A in the host defense against HBV.

ObjectiveViral hepatitis remains a major global health threat, causing approximately 1.3 million deaths in 2022. Despite substantial advances in vaccination and clinical treatment, it continues to impose a heavy disease burden across China. Existing studies have largely focused on single hepatitis subtypes and national epidemiological trends, with limited evidence on provincial heterogeneity. To fill this research gap, this study aimed to conduct a refined, region-specific epidemiological assessment of viral hepatitis in China.MethodsData were extracted from the Global Burden of Disease Study 2021 (GBD 2021) and the China Public Health Science Data Center to systematically analyze the epidemiological characteristics and spatiotemporal trends of viral hepatitis in China over the past three decades.ResultsThe overall burden of viral hepatitis in China decreased substantially over the study period, with obvious regional heterogeneity. Acute hepatitis A, B and E, as well as chronic hepatitis B and C, all presented prominent downward trends. The fastest declines in incidence were observed in acute hepatitis B (estimated annual percentage change [EAPC] = -3.03) and chronic hepatitis B (EAPC = -4.74). Notably, males suffered a higher disease burden for nearly all outcomes, except for HCV-related hepatocellular carcinoma, which predominantly affected females. Furthermore, provincial-level analysis indicated marked regional disparities: Xizang maintained a high incidence rate, while Beijing exhibited low incidence accompanied by strikingly high hepatitis-related mortality, suggesting a notable decoupling between infection prevalence and mortality.ConclusionsChina has achieved remarkable reductions in the overall burden of viral hepatitis, attributable to comprehensive public health interventions such as universal vaccination, standardized screening and improved sanitation conditions. Nevertheless, residual burdens in vulnerable populations and striking regional inequalities warrant targeted prevention and control strategies to reduce disease disparities nationwide.

BACKGROUND & AIMS:A notable proportion of CHB patients undergoing PEG-IFNα based therapy experience lagged serum HBeAg and/or HBV DNA disappearance in patients achieving HBsAg loss. In this study, we explored the molecular mechanisms behind this clinical phenomenon, offering novel insights into the sustainability of chronic HBV infection. METHODS:Two independent clinical cohorts were enrolled to validate this phenomenon. Then comprehensive analysis was performed using public datasets, coupled with a series of molecular biology experiments. RESULTS:Approximately 17-20% CHB patients underwent PEG-IFNα based therapy experienced seroclearance of HBsAg, while serum HBeAg and/or HBV DNA remained positive. These patients are more prone to serum HBsAg reappearance compared to those achieving complete virological response. Analysis of public datasets revealed that compared to the PC/BCP, the SP1/SP2 promoter displayed more pronounced inhibitory epigenetic modifications in HBeAg-negative patients and SP1/SP2 in-frame mutation peaked in immune active patients. In vitro experiments demonstrated that introduced SP1/SP2 inactive mutations would enhance PC/BCP transcriptional activity by a mechanism known as adjacent transcriptional interference. Furthermore, the deletion of L-HBsAg facilitated intracellular cccDNA replenishment. CONCLUSION:This study elucidates that under IFNα treatment and low viral load, transcriptional suppression of SP1/SP2 promoters through mutations and/or epigenetic changes would favour the maintenance of sustain chronic HBV infection, via enhancing the transcription activity of BCP to promote cccDNA replenishment. IMPACT AND IMPLICATIONS:In clinical practice with IFNα antiviral treatment for CHB patients, a "paradoxical" phenomenon is observed where serum HBsAg disappears while HBV DNA or/and HBeAg remains at low positive levels, with delayed disappearance. Our study confirms this clinical phenomenon using two independent clinical cohorts and explores the potential mechanisms behind the persistence of chronic HBV infection under IFNα treatment and low viral load. Transcriptional suppression of SP1/SP2 promoters through mutations and/or epigenetic changes supports the maintenance of chronic HBV infection by enhancing the transcriptional activity of the BCP, which in turn promotes cccDNA replenishment. HighlightsApproximately 20% of patients with CHB who have just achieved HBsAg loss under IFNα treatment show positive serum HBV DNA and/or HBeAg.During disease progression, in frame indel mutations accumulate in the HBV genome's SP1 and SP2 promoters, with epigenetic modifications contributing to their suppression.In frame indel mutations in the HBV genome's SP1 and SP2 promoters inhibit the transcription of HBV S mRNA and promote the transcription of 3.5 kb HBV RNA.The loss of L-HBs and envelop proteins leads to an increase in intracellular cccDNA, promoting the maintenance of chronic infection.

Liver fibrosis is a leading cause of liver-related mortality worldwide, yet effective therapies remain limited. Mesenchymal stem cells (MSCs) have recently shown promise in treating liver fibrosis due to their anti-inflammatory and anti-fibrotic properties. However, the precise molecular mechanisms by which MSCs exert their effects remain unclear. In this study, we explored how human umbilical cord-derived mesenchymal stem cells (hUC-MSCs) contribute to treating liver fibrosis, and revealed a crucial role of ferroptosis in modulating hepatic stellate cells (HSCs) activity. We found that MSCs primarily promote ferroptosis in HSCs in an exosome-dependent manner. Specifically, MSC-derived exosomes (MSC-Exos) deliver miR-499a-5p, which interacts with the transcription factor ETS1, leading to the suppression of GPX4, a key regulator of ferroptosis, thereby reducing the fibrogenic activity of HSCs. Overexpression of ETS1 in HSCs counteracted miR-499a-5p-induced ferroptosis, underscoring the pathway’s potential as a target for therapeutic intervention. Furthermore, molecular docking simulations further identified optimal ETS1-GPX4 binding sites. This research uncovers a novel mechanism by which MSCs may treat liver fibrosis, providing insights that could guide the development of more effective therapies for this widespread condition.

BACKGROUND & AIMS:Hepatitis B virus (HBV) extensively exploits host cellular machinery for productive infection. This study aimed to comprehensively identify and validate host factors critical for HBV infection using a functional genomics approach. METHODS:A whole-genome small-interfering RNA screen was performed in HepG2-NTCP cells, utilizing high-throughput AlphaLISA detection of intracellular HBV core and e antigens as the readout. Selected genes underwent rigorous multi-tiered validation: in vitro assessment of viral infection/replication via knockdown, overexpression, and knockout in hepatoma cell lines or primary human hepatocytes; analysis of gene expression in tumor/non-tumor tissues from 21 patients with HBV-related hepatocellular carcinoma; and in vivo evaluation using an AAV-HBV mouse model with target modulation. RESULTS:Validation confirmed nuclear receptor coactivator 5 (NCOA5) and chromodomain-helicase-DNA-binding protein 4 (CHD4) as essential proviral host factors; their knockdown significantly reduced HBV replication. Conversely, neuroblastoma RAS (NRAS) was identified as an antiviral factor. Mechanistically, NCOA5 likely operates via the estrogen receptor and hepatocyte nuclear factor 4 alpha (HNF4α) axis, while CHD4 modulates cccDNA histone modifications. NRAS knockdown enhanced HBV transcription by elevating HNF4α expression and inducing cell cycle arrest, which may explain the observed restriction of HBV replication in HBV-associated hepatocellular carcinoma tissues, where RAS hyperactivation frequently occurs. CONCLUSIONS:This study identifies NCOA5 and CHD4 as crucial proviral cofactors and NRAS as a potent antiviral factor regulating HBV replication. The findings highlight HBV's profound host dependence, uncover specific molecular mechanisms (involving HNF4α, epigenetic regulation of cccDNA, and cell cycle), and reveal validated host targets for potential therapeutic strategies against HBV infection. IMPACT AND IMPLICATIONS:Hepatitis B virus (HBV) needs human liver cell machinery to infect and multiply. We used large-scale genetic screening to find human proteins that either help or block HBV infection. We discovered two key proteins (NCOA5 and CHD4) that help HBV replicate, and one protein (NRAS) that blocks it. We confirmed these findings in human liver cells and mice. Understanding how these proteins control HBV (through regulating viral transcription, modifying viral DNA, or affecting cell growth) reveals potential new targets for developing better treatments against this serious liver infection.

Gene therapy using mRNA has facilitated progress in cancer therapy. However, its application is hindered by a limited tumor-targeted delivery approach, leading to off-target effects and safety concerns. Chimeric antigen receptor (CAR) molecules enable T cells to recognize specific antigens in a major histocompatibility complex-unrestricted manner. CAR approaches provide an "off-the-shelf" solution for introducing additional targeting functionality to a cell membrane. Cancer cell membrane-coated nanoparticles with homotypic tumor-targeted properties provide a readily accessible platform for gene engineering and membrane extraction. Herein, we demonstrate a CAR-inspired cancer cell membrane-coated platform for delivering an mRNA formulation through a dual tumor-targeted mechanism. The simplified human epidermal growth factor receptor 2 (HER2)-specific CAR molecule (comprising an extracellular HER2-binding domain, a hinge, and a transmembrane domain) was engineered on the cell membrane of cancer cells to establish CAR-CT26 cells. The extracted CAR-CT26 membrane (CARM) was subsequently coated onto the lipid nanoparticle (LNP)-mRNA surface to form a CARM@LNP-mRNA complex. In vitro, the CARM-coated nanoparticles exhibited enhanced mRNA transfection efficiency toward CT26 cells overexpressing target HER2 antigens. Systemic administration of the CARM@LNP-mRNA formulation resulted in stronger tumor-targeting ability and tumor suppression in HER2+ CT26 subcutaneous tumors and peritoneal cavity metastasis models than that observed with the CT26 cell membrane-coated version. Our data suggest that CARM@LNP is a feasible choice for mRNA-based gene therapy. These results provide evidence for the systemic administration of CARM@LNP-mRNA as a promising tumor-targeted therapeutic strategy.

Hepatitis B virus (HBV) infection is a major etiological factor in the development of hepatocellular carcinoma (HCC). Despite extensive research efforts, the precise molecular mechanisms and critical host factors driving HBV-induced epithelial-mesenchymal transition (EMT), liver fibrosis and hepatocarcinogenesis remain to be explored. Emerging evidence has identified aberrant expression of Troponin T1 (TNNT1) in malignancies, implicating its potential role in HCC progression. However, the specific role and mechanism of TNNT1 in HBV-associated HCC remain elusive. In this study, we demonstrate that TNNT1 expression is markedly upregulated in HBV-positive HCC tissues, HBV infection/replication cell models and AAV-HBV1.3-infected mouse models. Mechanistically, HBV activates the transcription factor c-Myc via the PI3K/AKT/mTOR signaling pathway. HBV promotes HCC cell proliferation and EMT markers (Cyclin D1, Vimentin increased, E-cadherin decreased) and liver fibrosis marker α-smooth muscle actin (α-SMA) expression in a TNNT1-dependent manner. HBV infection-induced EMT and liver fibrosis can be abolished by hepatic-specific TNNT1 knockout or knockdown in mice. These findings provide novel insights into the role of TNNT1 in HBV-driven EMT and liver fibrosis, and establish a foundation for further exploration of TNNT1 as a potential therapeutic target in HBV-associated HCC progress.