Biology subjects

Zoulim, F.

Publications and source records attributed to Zoulim, F..

10 recordsLinked to original sources

bioRxiv2026

Adenine Base Editing Potently Suppresses Hepatitis B Surface Antigen Expression and Inhibits Hepatitis D Virus Release

Background and AimsNovel antiviral approaches capable of permanently inactivating the intrahepatic HBV DNA reservoir, the covalently closed circular DNA (cccDNA) and HBV DNA integrated into the host genome, are urgently needed. This study evaluated adenine base editing as a strategy to disrupt HBV replication by introducing mutations in the overlapping HBs/polymerase open reading frame (ORF). MethodsAn adenine base editor (ABE) and 3 guide RNAs (gS1-gS3) were designed to introduce missense mutations within the HBs/polymerase ORF. ABE mRNA and individual gRNAs were co-transfected into HBV-infected HepG2-hNTCP cells and primary human hepatocytes. Antiviral efficacy was further assessed in HepG2.2.15 and PLC/PRF/5 cells harboring integrated HBV DNA. In vivo, lipid nanoparticles (LNP)-mediated delivery of ABE mRNA and gRNAs was evaluated in HBVcircle DNA-transduced mice and in HBV-infected human liver-chimeric mice. The impact of HBs editing on hepatitis D virus (HDV) release was assessed using PLC/PRF/5 and Huh7 cell-based HDV replication models. ResultsAdenine base editing efficiently reduced HBsAg production and HBV replication in vitro by targeting both cccDNA and integrated HBV DNA. A single LNP injection of ABE-gS2 resulted in undetectable HBsAg in HBVcircle mice, while two injections achieved a 90% reduction in serum HBsAg in HBV-infected human liver chimeric mice. HBV DNA replication was also inhibited in vivo. Furthermore, HBs ORF base editing markedly suppressed HDV release in vitro. ConclusionsAdenine base editing of the HBs ORF effectively impairs HBV replication and HBsAg production in vitro and in vivo and concomitantly inhibits HDV release, highlighting its therapeutic potential.

molecular biology↗

bioRxiv2025

Precision-cut liver slices as a model for the evaluation of host-targeting agents against hepatitis B and delta viruses

Background: Developing new therapeutic strategies against hepatitis B virus (HBV) and hepatitis delta virus (HDV) is essential to cure these infections. Yet evaluation of host-targeting agents (HTAs) with in vitro/in vivo models remains challenging. Therefore, we assessed precision-cut liver slices (PCLS) as an HBV/HDV co-infection model to study virus-host interactions and HTAs. Methods: We generated PCLS from human liver resections and infected them ex vivo with HBV and HDV. Tissue viability and architecture were monitored by intracellular ATP, secreted albumin, and multiplexed immunofluorescence. Viral markers were assessed by quantitative PCR, western blot, and light-sheet microscopy in infected slices following treatment with a sodium taurocholate co-transporting polypeptide (NTCP)-targeting peptide, lonafarnib, or the Toll-like receptor 8 agonist selgantolimod (SLGN). Single-cell RNA sequencing was performed to characterize the cellular responses to SLGN. Results: Here we show that our ex vivo infection protocol allows the establishment of HBV and HDV infection within the liver's three-dimensional architecture. Treatment with three well-characterized HTAs produced distinct antiviral effects consistent with each mechanism: an NTCP-targeting peptide blocked entry; lonafarnib induced intracellular hepatitis delta antigen accumulation; SLGN showed anti-HBV activity not previously seen in cultured hepatocytes, indicating cross-talk between immune and infected cells within liver slices. Conclusion: These results provide the characterization of PCLS as an ex vivo model of HBV/HDV co-infection and antiviral testing. In the future, PCLS could contribute to expediting pre-clinical characterization of HTAs and to exploring alternatives to animal experimentation.

microbiology↗

bioRxiv2025

DDX5 and DDX17 RNA helicases regulate hepatitis B virus RNA splicing

Chronic HBV infection remains a major health burden worldwide and is the main driver of severe liver diseases. Liver pathogenesis is associated with the increased proportion of HBV spliced variants that encode viral proteins involved in liver disease progression. However, how HBV RNA splicing is regulated is poorly understood. Here, we focused on DDX5 and DDX17 RNA helicases, known to regulate HBV RNA metabolism and alternative splicing of host genes. By performing 5RACE-PCR combined with single molecule sequencing, we demonstrated that silencing both proteins increased the usage of a specific splicing donor site and the expression of the derived HBV spliced variants. Polysome fractionation highlighted the ability of these RNA species to encode new viral proteins potentially contributing to liver pathogenesis. Overall, our data established DDX5 and DDX17 helicases as master regulators of HBV RNA metabolism, by fine-tuning viral splicing, which is linked to HBV-induced liver pathogenesis and disease progression.

molecular biology↗

bioRxiv2024

Bolero: a dedicated workflow to decipher Hepatitis B virus transcriptome from long-reads sequencing method coupled to 5RACE amplification of transcripts

Hepatitis B virus (HBV) represents a major health burden, as it affects close to 290 million people worldwide. Although prophylactic vaccines are available, current therapeutic compounds do not usually achieve HBV eradication due to the persistence of the covalently closed circular (ccc)DNA that serves as viral reservoir. Thus, novel biomarkers that reliably reflect intrahepatic cccDNA transcriptional activity would be highly relevant for the monitoring of infected individuals, as well as the evaluation of new treatments targeting HBV. In this context, the development of 5 rapid amplification of complementary DNA ends (5RACE) as a strategy to capture and amplify full-length HBV RNAs, coupled with long-read and full-length sequencing approaches (e.g., Oxford Nanopore Technology), has recently enabled the detailed characterization of these molecules. The analysis of such data requires a dedicated bioinformatics pipeline due to the highly condensed nature of the HBV genome, which is characterized by the production of multiple transcripts and spliced variants that overlap each other. Here, we present Bolero, a computational method and built-in workflow designed to handle HBV sequencing data and evaluate the relative expression of viral RNAs and their spliced variants. The analysis of HBV-infected cell lines demonstrates that our bioinformatics pipeline is efficient for the identification and quantification of individual HBV mRNAs. Thus, Bolero represents a useful tool to study cccDNA transcriptional activity and the heterogeneity of HBV RNA spliced variants. Author summaryTranscriptomic analyses have brought comprehensive insights in the mechanisms controlling gene expression. Moreover, with the recent advances in sequencing technologies and computational methods, researchers can nowadays not only quantify gene expression, but also study alternative splicing, polyadenylation, transcription initiation, and even rare phenomena such as distant gene fusions. However, conventional analysis tools still rely heavily on the assumption of linear genomes with minimal overlap between open reading frames, rendering them insufficient for studying complex viruses such as hepatitis B virus (HBV). Unlike typical linear genomes, HBV genome consists in a circular DNA molecule, which results in an extensive sequence overlap between its transcripts. To tackle these challenges, we developed an innovative approach coupling 5 rapid amplification of complementary DNA ends (5RACE) and long-read sequencing to comprehensively explore the HBV transcriptome. Furthermore, we developed Bolero, a computational method designed to handle the peculiarities of HBV sequencing data, which allows a detailed characterization of the HBV transcriptome.

bioinformatics↗

bioRxiv2024

Helicases DDX5 and DDX17 promote Hepatitis B Virus transcription termination heterogeneity in infected human hepatocytes

Background & AimsTranscription termination fine tunes gene expression and contributes to specify the function of RNAs in eukaryotic cells. Transcription termination of hepatitis B virus (HBV) is subjected to the recognition of the canonical polyadenylation signal (cPAS) common to all viral transcripts. The regulation of the usage of this cPAS and its impact on viral gene expression and replication is currently unknown. Approach & ResultsTo unravel the regulation of HBV transcript termination, we implemented a 3 RACE-PCR assay coupled to single molecule sequencing both in in vitro infected hepatocytes and in chronically infected patients. The detection of a previously unidentified transcriptional readthrough indicated that the cPAS was not systematically recognized during HBV replication in vitro and in vivo. Gene expression downregulation experiments demonstrated a role for the RNA helicases DDX5 and DDX17 in promoting viral transcriptional readthrough, which was, in turn, associated to HBV RNA destabilization and decreased HBx protein expression. RNA and chromatin immunoprecipitation, together with mutation of cPAS sequence suggested a direct role of DDX5 and DDX17 in functionally linking cPAS recognition to transcriptional readthrough, HBV RNA stability and replication. ConclusionsOur findings identify DDX5 and DDX17 as crucial determinants for HBV transcriptional fidelity and as host restriction factors for HBV replication.

molecular biology↗

bioRxiv2023

Replication-driven HBV cccDNA loss in chimeric mice with humanized livers

Hepatitis B virus (HBV) infection is largely noncytopathic and requires the establishment of covalently closed circular DNA (cccDNA), which is considered stable in the nuclei of infected cells. Although challenging, approaches to directly target cccDNA molecules or kill infected cells are recommended to eliminate cccDNA. Herein, cccDNA levels were investigated in HBV-infected chimeric mice with humanized livers. HBV-infected cells support robust replication, progressively retain viral products, and head for cytopathic destruction and cccDNA loss. It is difficult for infected cells to retain cccDNA and remain noncytopathic. Replication-driven cccDNA loss is observed at both phases of spread of and persistent infection. The cccDNA replenishment is required to compensate for cccDNA loss. Blocking cccDNA replenishment pathways reduces cccDNA levels by >100-fold. These results prove an unconventional cccDNA elimination strategy that does not directly target cccDNA but aims to transform spontaneous cccDNA loss into progressive cccDNA elimination by blocking cccDNA replenishment.

microbiology↗

bioRxiv2022

Hepatocellular carcinoma hosts immature neurons and cholinergic tumors that correlate with adverse molecular features and outcomes

Background & aimsThe unexplained interpatient variation in hepatocellular carcinoma (HCC) remains a major challenge. We aimed at addressing the under-explored association between the disease and the hepatic autonomic nervous system (ANS). Methods & ResultsWe in-depth characterized the innervation of French biobanks HCC samples by conventional biochemistry methods. We also applied bioinformatics approaches to the TCGA dataset in order to stratify samples according to neural features and molecular correlates. We highlighted the predominant parasympathetic polarity of HCC nerves, and demonstrated that a cirrhotic rat model of aggressive HCC hosts liver neurogenesis with cholinergic features. Using the TCGA dataset, we then defined an HCC neural signature, derived from adrenergic and cholinergic receptor levels, that allowed patient stratification into two classes. Cholinergic tumors correlated with TP53 mutations (p [≤] 0.05), shorter progression-free interval (PFI) and overall survival (OS), displayed more pathogenic molecular traits (e.g., AFP-rich, proliferative tumors, mitotic functions including DNA repair, EMT, Ras, and Akt/mTOR pathways), aggressive HCC signatures and B cell accumulation. Instead, adrenergic tumors, predominant in patients aged >60 and with mutated CTNNB1, were correlated with better OS and PFI (p < 0.05), and numerous immune pathways. ConclusionsOur results depict neural features of HCC and how the existing tumor classification may also be shaped by neural inputs. Altogether, we show that the parasympathetic branch of the ANS is implicated in the pathobiology of HCC, and advocate for the use of ANS-targeting drugs in HCC research, many of which are clinically safe and well characterized.

cancer biology↗

bioRxiv2022

Performance of the cobas(R) HBV RNA Automated Investigational Assay for the Detection and Quantification of Circulating HBV RNA in Chronic HBV Patients

BackgroundThe amount of HBV RNA in peripheral blood may reflect HBV covalently closed circular DNA (cccDNA) transcriptional activity within infected hepatocytes. Quantification of circulating HBV RNA (cirB-RNA) is thus a promising biomarker for monitoring antiviral treatment. ObjectivesWe evaluated the performance of an automated, prototype quantitative HBV RNA assay for use on the Roche cobas(R) 6800/8800 systems. Study DesignThe sensitivity, specificity, linearity, and potential interference by HBV DNA of the cobas(R) HBV RNA assay were assessed using synthetic HBV armored RNA and clinical specimens. Resultscobas(R) HBV RNA results were linear between 10 and 107 copies/mL in clinical samples of several HBV genotypes, and up to 109 copies/mL with synthetic RNA. Precision and reproducibility were excellent, with standard deviation below 0.15 log10 copies/mL and coefficients of variation below 5% throughout the linear range. The presence of HBV DNA had minimal (<0.3 log10 copies/mL) impact on HBV RNA quantification at DNA:RNA ratios of up to approximately one million. In a panel of 36 untreated patient samples, cirB-RNA concentrations were approximately 200-fold lower than HBV DNA. cirB-RNA was detected in all 13 HBeAg-positive patients (mean 6.0 log10 copies/mL), and in 20 of 23 HBeAg-negative patients (mean of quantifiable samples 2.2 log10 copies/mL). Finally, cirB-RNA was detected in 12 of 20 nucleoside analog-treated patients (mean of quantifiable samples 3.4 log10 copies/mL). ConclusionsThe cobas(R) 6800/8800 investigational HBV RNA assay is a high throughput, sensitive and inclusive assay to evaluate the clinical relevance of cirB-RNA quantification in patients with chronic hepatitis B.

microbiology↗

bioRxiv2020

Hepatitis B virus Core protein nuclear interactome identifies SRSF10 as a host RNA-binding protein restricting HBV RNA production

Despite the existence of a preventive vaccine, chronic infection with Hepatitis B virus (HBV) affects more than 250 million people and represents a major global cause of hepatocellular carcinoma (HCC) worldwide. Current clinical treatments, in most of cases, do not eliminate viral genome that persists as a DNA episome in the nucleus of hepatocytes and constitutes a stable template for the continuous expression of viral genes. Several studies suggest that, among viral factors, the HBV core protein (HBc), well-known for its structural role in the cytoplasm, could have critical regulatory functions in the nucleus of infected hepatocytes. To elucidate these functions, we performed a proteomic analysis of HBc-interacting host-factors in the nucleus of differentiated human hepatocytes. The HBc interactome was found to consist primarily of RNA-binding proteins (RBPs), which are involved in various aspects of mRNA metabolism. Among them, we focused our studies on SRSF10, a RBP that was previously shown to regulate alternative splicing in a phosphorylation-dependent manner and to control stress and DNA damage responses, as well as viral replication. Functional studies combining SRSF10 knockdown and a pharmacological inhibitor of SRSF10 phosphorylation (1C8) showed that SRSF10 behaves as a restriction factor that regulates HBV RNAs levels and that its dephosphorylated form is likely responsible for the anti-viral effect. Surprisingly, neither SRSF10 knock-down nor 1C8 treatment modified the splicing of HBV RNAs but rather modulated the level of nascent HBV RNA. Altogether, our work suggests that in the nucleus of infected cells HBc interacts with multiple RBPs that regulate viral RNA metabolism. Our identification of SRSF10 as a new anti-HBV restriction factor offers new perspectives for the development of new host-targeted antiviral strategies. Author SummaryChronic infection with Hepatitis B virus (HBV) affects more than 250 millions of people world-wide and is a major global cause of liver cancer. Current treatments lead to a significant reduction of viremia in patients. However, viral clearance is rarely obtained and the persistence of the HBV genome in the hepatocytes nucleus generates a stable source of viral RNAs and subsequently proteins which play important roles in immune escape mechanisms and liver disease progression. Therapies aiming at efficiently and durably eliminating viral gene expression are still required. In this study, we identified the nuclear partners of the HBV Core protein (HBc) to understand how this structural protein, responsible for capsid assembly in the cytoplasm, could also regulate viral gene expression. The HBc interactome was found to consist primarily of RNA-binding proteins (RBPs). One of these RBPs, SRSF10, was demonstrated to restrict HBV RNA levels and a drug, able to alter its phosphorylation, behaved as an antiviral compound capable of reducing viral gene expression. Altogether, this study sheds new light novel regulatory functions of HBc and provides information relevant for the development of antiviral strategies aiming at preventing viral gene expression.

microbiology↗

bioRxiv2020

Landscape of oncoviral genotype and co-infection via Human papilloma andHepatitis B viral tumor in-situ profiling

Hepatitis B virus (HBV) and human papillomavirus (HPV) infection are known risk factors for developing several cancers. However, the effect of viral genotype and co-infection in actually driving oncogenesis remains unclear. We have developed and deployed a new scalable, high throughput tool (ViralMine) for sensitive and precise oncoviral genotype deconvolution using tumor RNA sequencing data from 537 virally infected liver, cervical, and head and neck tumors. We provide the first comprehensive integrative landscape of tumor-viral gene expression, viral antigen immunogenicity, patient survival, and mutational profiling organized by tumor onco-viral genotype. We find that HBV and HPV genotype, and surprisingly high rates of multi-genotype co-infection, serve as significant predictors of patient survival, tumor immune responsiveness, and APOBEC activity modulation. Finally, we demonstrate that HPV genotype strongly associates with viral onco-gene expression over cancer type, implying expression may be similar across episomal and stochastic integration-based infections. Significance StatementWe demonstrate that scalable, high-accuracy oncoviral genotyping, gene expression, and co-infection estimation is feasible from legacy tumor RNA-seq data. While HBV and HPV genotype are known risk factors for oncogenesis, viral genotype and co-infection are shown to strongly associate with disease progression, patient survival, mutational signatures, and putative tumor neoantigen immunogenicity, facilitating novel clinical associations with infections.

cancer biology↗