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HBV expresses more than 10 spliced RNAs from the viral pregenomic RNA, but their functions remain elusive and controversial. To address the function of HBV spliced RNAs, we generated splicing-deficient HBV mutants and conducted experiments to assess the impact of these mutants on HBV infection. HepG2-NTCP cells, human hepatocyte chimeric FRG mice (hu-FRG mice), and serum from patients with chronic hepatitis B were used for experiments on HBV infection. Additionally, SHifter assays and cryo-electron microscopy were performed. We found the infectivity of splicing-deficient HBV was decreased 100-1,000-fold compared with that of wild-type HBV in hu-FRG mice. Another mutant, A487C, which loses the most abundant spliced RNA (SP1), also exhibits severely impaired infectivity. SP1 hypothetically encodes a novel protein HBcSP1 (HBc-Cys) that lacks the C-terminal cysteine from full-length HBc. In the SHifter assay, HBcSP1 was detected in wild-type viral particles at a ratio of about 20-100% vs. conventional HBc, as well as in the serum of patients with chronic hepatitis B, but not in A487C particles. When infection was conducted with a shorter incubation time of 4-8 h at lower PEG concentrations in HepG2-NTCP cells, the entry of the A487C mutant was significantly slower. SP1 cDNA complementation of the A487C mutant succeeded in rescuing its infectivity in hu-FRG mice and HepG2-NTCP cells. Moreover, cryo-electron microscopy revealed a disulfide bond between HBc cysteine 183 and 48 in the HBc intradimer of the A487C capsid, leading to a locked conformation that disfavored viral entry in contrast to the wild-type capsid. Prior studies unveiled the potential integration of the HBc-Cys protein into the HBV capsid. We confirmed the proposal and validated its identity and function during infection. HBV SP1 RNA encodes a novel HBc protein (HBcSP1) that lacks the C-terminal cysteine from conventional HBc (HBc-Cys). HBcSP1 was detected in cell culture-derived HBV and confirmed in patients with chronic infection by both immunological and chemical modification assays at 10-50% of capsid. The splicing-deficient mutant HBV (A487C) impaired infectivity in human hepatocyte chimeric mice and viral entry in the HepG2-NTCP cell line. Furthermore, these deficiencies of the splicing-deficient mutant could be rescued by complementation with the SP1-encoded protein HBcSP1. We confirmed and validated the identity and function of HBcSP1 during infection, building on the current model of HBV particles. [Display omitted] • The infectivity of splicing-deficient HBV was significantly decreased compared to WT HBV in hu-FRG mice. • SP1 RNA encodes HBcSP1, which is found in 10 to 50% of nucleocapsids in patients with CHB and cell line-derived WT HBV. • The splicing-deficient mutant A487C, lacking HBcSP1, reduces the efficiency of viral entry kinetics. • Disulfide bonds between Cys48 and Cys183 in the A487C capsid led to a locked conformation that disfavored viral entry. [ABSTRACT FROM AUTHOR]

Background/Aims: Chronic hepatitis B virus (HBV) infection still poses a major threat to global health. Oligoadenylate synthetase–ribonuclease L (RNase L) antiviral pathway is one of interferon‐induced antiviral effectors. The relationship between RNase L and HBV has never been investigated and we aim to examine the serum RNase L levels in patients with different stages of chronic HBV infection. Methods: The patients were enrolled from 1985 to 2000, who had been HBsAg positive for longer than 6 months, at the National Taiwan University Hospital. In total, 426 patients with chronic HBV infection were included in this study, including 135 inactive carriers, 148 cirrhosis, and 143 hepatocellular carcinoma (HCC) cases. Results: The RNase L levels increase as the disease severity increases. Higher RNase L levels were associated with higher HBV viral load, and the HBV‐RNase L relationship was replaced by the disease severity status when adding disease status into the model. Compared with inactive carriers, the risk of liver cirrhosis was 60‐fold (odds ratio = 60.8, 95% confidence interval = 3.49–1061) with the highest quintile of RNase L levels, after the adjustment of HBV DNA. The dose–response trend was statistically significant with quintiles and one increment of RNase L level in relation to liver cirrhosis. Similar results were found when HCC was compared with inactive carriers, while there was no association when compared between liver cirrhosis and HCC. Conclusions: A positive relationship between serum RNase L and HBV viral titers or advanced disease status is uncovered in this study. Further investigation in this area may provide more details of an innate immune response for HBV and opportunity for novel therapeutic strategy. [ABSTRACT FROM AUTHOR]

Summary: Background: Lipid‐lowering effect was observed during treatment with tenofovir disoproxil fumarate (TDF) for chronic hepatitis B (CHB). However, the metabolic features in patients switching from TDF to tenofovir alafenamide (TAF) remain unclear. Aims: To compare the impacts of switching from TDF to TAF or from entecavir to TAF on body weight and metabolic features in patients with CHB. Methods: This was a multi‐centre, prospective, observational study in patients with CHB on TDF or entecavir who switched to TAF. Baseline characteristics, lipid profile and sugar profile were determined. This study received IRB approval from each hospital. Results: We enrolled 177 patients on TDF (99) or entecavir (78) and followed them for 48 weeks after the switch to TAF. At baseline, TDF‐experienced patients had lower serum triglyceride, total cholesterol, high‐density lipoprotein (HDL) cholesterol and low‐density lipoprotein (LDL) cholesterol than entecavir‐experienced patients. The switch from TDF to TAF significantly increased body weight, triglyceride, total cholesterol, HDL, LDL, fasting glucose, glycaemic haemoglobin, insulin and insulin resistance. The switch from entecavir to TAF did not affect these measures. There was no significant difference in atherosclerotic cardiovascular disease risk scores between groups. Conclusions: The switch from TDF to TAF was associated with weight gain, derangements of lipid profile, and increased insulin resistance in patients with CHB. Long‐term effects on these metabolic features need further investigation. [ABSTRACT FROM AUTHOR]

Hepatocellular carcinoma (HCC) usually recurs after curative surgical resection. Currently, no approved adjuvant therapy has been shown to reduce HCC recurrence rates. In this study, the in vivo effect of sequential combination treatment with recombinant mouse interferon-alpha (rmIFN-α) and an anti-mouse-PD1 antibody on hepatitis B virus (HBV) clearance in mice was evaluated. A Phase I clinical trial was then conducted to assess the safety, tolerability, and inhibitory activity of sequential therapy with ropeginterferon alfa-2b and nivolumab in patients with HCC recurrence who underwent curative surgery for HBV-related HCC. The animal modeling study showed that HBV suppression was significantly greater with the rmIFN-α and anti-PD1 sequential combination treatment in comparison with sole treatment with rmIFN-α or anti-PD1. In the Phase I study, eleven patients completed the sequential therapy with ropeginterferon alfa-2b every two weeks for six doses at 450 µg, followed by three doses of nivolumab every two weeks up to 0.75 mg/kg. A notable decrease in or clearance of HBV surface antigen was observed in two patients. The dose-limiting toxicity of grade 3 alanine transaminase and aspartate aminotransferase increases was observed in one patient. The maximum tolerated dose was then determined. To date, no HCC recurrence has been observed. The treatment modality was well tolerated. These data support the further clinical development of sequential combination therapy as a post-surgery prophylactic measure against the recurrence of HBV-related HCC. [ABSTRACT FROM AUTHOR]