More than 350 million people worldwide have been persistently infected with the hepatitis B virus (HBV). Chronic HBV infection could advance toward liver cirrhosis and hepatocellular carcinoma. The intervention with prophylactic vaccine and conventional treatment could suppress HBV, but could not completely eradicate it. The major obstacle for investigating curative antiviral drugs are the incompetence of hepatocyte models that should have closely imitated natural human infection. Here, we demonstrated that an immortalized hepatocyte-like cell line (imHC) could accommodate for over 30 days the entire life cycle of HBV prepared from either established cultured cells or clinically-derived fresh isolates. Normally, imHCs had intact interferon signaling with anti-viral action. Infected imHCs responded to treatments with direct-acting antiviral drugs (DAAs) and interferons (IFNs) by diminishing HBV DNA, the covalently closed circular DNA (cccDNA) surface antigen of HBV (HBsAg, aka the Australia antigen) and the hepatitis B viral protein (HBeAg). Notably, we could observe and quantify HBV spreading from infected cells to naïve cells using an imHC co-culture model. In summary, this study constructed a convenient HBV culture model that allows the screening for novel anti-HBV agents with versatile targets, either HBV entry, replication or cccDNA formation. Combinations of agents aiming at different targets should achieve a complete HBV eradication.

Background/Objectives: Gut microbiota has been implicated in the pathogenesis of metabolic dysfunction-associated steatotic liver disease (MASLD) and cardiovascular disease (CVD). This study aimed to identify associations between gut dysbiosis and MASLD, regarding body mass index (BMI) and subclinical coronary atherosclerosis (SCA). Methods: We conducted a cross-sectional study of 202 patients with MASLD who had no previous history of CVD. The severity of MASLD was evaluated using a magnetic resonance imaging-based method, and SCA was measured by assessing coronary artery calcification (CAC). Gut microbiota was assessed in fecal specimens using sequencing targeting the V4 region of the 16S rRNA gene. Results: Our results demonstrated that gut microbial profiles between low- and high-BMI groups (<30 vs. ≥30 kg/m²) differed significantly in beta-diversity, but not in alpha-diversity indices. At the genus level, we identified Megamonas, Sutterella, Catenibacterium, and Odoribacter, enriched in the high BMI group. Compared to the low CAC group (<100 AU), MASLD patients with high CAC scores (≥100 AU) exhibited enrichment in Ruminococcus gnavus, Bacteroides, and Lachnoclostridium, along with depletion of several short-chain fatty acid (SCFA)-producing bacteria, such as Faecalibacterium. Multivariate analysis demonstrated that older age, the presence of diabetes, high BMI, fibrosis stage F3-F4, and high plasma trimethylamine oxide (TMAO) levels were independently associated with a high CAC score in patients with MASLD. Conclusions: These data indicated that gut dysbiosis and related metabolites, in association with advanced liver disease, were potential contributors to the progression of SCA in obese patients with MASLD.

Hepatitis B virus (HBV) persists in infected hepatocytes through covalently closed circular DNA (cccDNA), a stable episomal form that serves as the transcriptional template for viral replication. Accurate and sensitive quantification of intrahepatic cccDNA is crucial for evaluating antiviral therapies, particularly those targeting a functional cure. Here, we report the development of a novel, cccDNA-specific detection system combining recombinase polymerase amplification (RPA) with CRISPR/Cas12a-based fluorescence detection. We designed and validated CRISPR RNAs (crRNAs) targeting HBV cccDNA-specific regions conserved across genotypes A–D. Reaction conditions for both RPA and Cas12a detection were optimized to enhance sensitivity, specificity, and accuracy. The system reliably detected as few as 10 copies of cccDNA-containing plasmid per reaction and showed no cross-reactivity with non-cccDNA forms in serum or plasma, indicating assay specificity. When applied to liver tissue samples from 10 HBV-infected and 6 non-HBV patients, the RPA-CRISPR/Cas12a assay exhibited a high sensitivity (90%) and a strong correlation with qPCR results (R² = 0.9155), confirming its accuracy. In the conclusion, the RPA-CRISPR/Cas12a system provides a robust, cost-effective, and scalable platform for sensitive and specific quantification of intrahepatic HBV cccDNA. This method holds promises for research and high-throughput therapeutic screening applications targeting cccDNA clearance.