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Antiviral Research Oct 2020Hepatitis B virus (HBV) specifically infects hepatocytes and causes severe liver diseases. The HBV life cycle is unique in that the genomic DNA (relaxed-circular... (Review)
Review
Hepatitis B virus (HBV) specifically infects hepatocytes and causes severe liver diseases. The HBV life cycle is unique in that the genomic DNA (relaxed-circular partially double-stranded DNA: rcDNA) is converted to a molecular template DNA (covalently closed circular DNA: cccDNA) to amplify a viral RNA intermediate, which is then reverse-transcribed back to viral DNA. The highly stable characteristics of cccDNA result in chronic infection and a poor rate of cure. This complex life cycle of HBV offers a variety of targets to develop antiviral agents. We provide here an update on the current knowledge of HBV biology and its life cycle, which may help to identify new antiviral targets.
Topics: Antiviral Agents; DNA, Viral; Hep G2 Cells; Hepatitis B; Hepatitis B virus; Hepatocytes; Host Microbial Interactions; Humans; Virus Replication
PubMed: 32866519
DOI: 10.1016/j.antiviral.2020.104925 -
Gut Jan 2023A comprehensive immune landscape for HBV infection is pivotal to achieve HBV cure.
OBJECTIVE
A comprehensive immune landscape for HBV infection is pivotal to achieve HBV cure.
DESIGN
We performed single-cell RNA sequencing of 2 43 000 cells from 46 paired liver and blood samples of 23 individuals, including six immune tolerant, 5 immune active (IA), 3 acute recovery (AR), 3 chronic resolved and 6 HBV-free healthy controls (HCs). Flow cytometry and histological assays were applied in a second HBV cohort for validation.
RESULTS
Both IA and AR were characterised by high levels of intrahepatic exhausted CD8+ T (Tex) cells. In IA, Tex cells were mainly derived from liver-resident GZMK+ effector memory T cells and self-expansion. By contrast, peripheral CX3CR1+ effector T cells and GZMK+ effector memory T cells were the main source of Tex cells in AR. In IA but not AR, significant cell-cell interactions were observed between Tex cells and regulatory CD4+ T cells, as well as between Tex and FCGR3A+ macrophages. Such interactions were potentially mediated through human leukocyte antigen class I molecules together with their receptors CANX and LILRBs, respectively, contributing to the dysfunction of antiviral immune responses. By contrast, CX3CR1+GNLY+ central memory CD8+ T cells were concurrently expanded in both liver and blood of AR, providing a potential surrogate marker for viral resolution. In clinic, intrahepatic Tex cells were positively correlated with serum alanine aminotransferase levels and histological grading scores.
CONCLUSION
Our study dissects the coordinated immune responses for different HBV infection phases and provides a rich resource for fully understanding immunopathogenesis and developing effective therapeutic strategies.
Topics: Humans; CD8-Positive T-Lymphocytes; Liver; Antiviral Agents; T-Lymphocytes, Regulatory; Sequence Analysis, RNA; Hepatitis B virus
PubMed: 35361683
DOI: 10.1136/gutjnl-2021-325915 -
Advances in Experimental Medicine and... 2020Chronic hepatitis B virus (HBV) infection remains to be a serious threat to public health and is associated with many liver diseases including chronic hepatitis B (CHB),... (Review)
Review
Chronic hepatitis B virus (HBV) infection remains to be a serious threat to public health and is associated with many liver diseases including chronic hepatitis B (CHB), liver cirrhosis, and hepatocellular carcinoma. Although nucleos(t)ide analogues (NA) and pegylated interferon-α (Peg-IFNα) have been confirmed to be efficient in inhibiting HBV replication, it is difficult to eradicate HBV and achieve the clinical cure of CHB. Therefore, long-term therapy has been recommended to CHB treatment under the current antiviral therapy. In this context, the new antiviral therapy targeting one or multiple critical steps of viral life cycle may be an alternative approach in future. In the last decade, the functional receptor [sodium-taurocholate cotransporting polypeptide (NTCP)] of HBV entry into hepatocytes has been discovered, and the immature nucleocapsids containing the non- or partially reverse-transcribed pregenomic RNA, the nucleocapsids containing double-strand linear DNA (dslDNA), and the empty particles devoid of any HBV nucleic acid have been found to be released into circulation, which have supplemented the life cycle of HBV. The understanding of HBV life cycle may offer a new instruction for searching the potential antiviral targets, and the new viral markers used to monitor the efficacy of antiviral therapy for CHB patients in the future.
Topics: Antiviral Agents; Hepatitis B virus; Hepatitis B, Chronic; Hepatocytes; Humans; Interferon-alpha; Virus Internalization; Virus Replication
PubMed: 31741332
DOI: 10.1007/978-981-13-9151-4_2 -
Viruses May 2023Virus-like particles (VLPs) have gained a lot of interest within the past two decades. The use of VLP-based vaccines to protect against three infectious agents-hepatitis... (Review)
Review
Virus-like particles (VLPs) have gained a lot of interest within the past two decades. The use of VLP-based vaccines to protect against three infectious agents-hepatitis B virus, human papillomavirus, and hepatitis E virus-has been approved; they are very efficacious and offer long-lasting immune responses. Besides these, VLPs from other viral infectious agents (that infect humans, animals, plants, and bacteria) are under development. These VLPs, especially those from human and animal viruses, serve as stand-alone vaccines to protect against viruses from which the VLPs were derived. Additionally, VLPs, including those derived from plant and bacterial viruses, serve as platforms upon which to display foreign peptide antigens from other infectious agents or metabolic diseases such as cancer, i.e., they can be used to develop chimeric VLPs. The goal of chimeric VLPs is to enhance the immunogenicity of foreign peptides displayed on VLPs and not necessarily the platforms. This review provides a summary of VLP vaccines for human and veterinary use that have been approved and those that are under development. Furthermore, this review summarizes chimeric VLP vaccines that have been developed and tested in pre-clinical studies. Finally, the review concludes with a snapshot of the advantages of VLP-based vaccines such as hybrid/mosaic VLPs over conventional vaccine approaches such as live-attenuated and inactivated vaccines.
Topics: Animals; Humans; Vaccines, Virus-Like Particle; Viruses; Hepatitis B virus; Vaccine Development
PubMed: 37243195
DOI: 10.3390/v15051109 -
Signal Transduction and Targeted Therapy Feb 2023Hepatitis B virus (HBV) infection is a major risk factor for hepatocellular carcinoma (HCC), but its pathogenic mechanism remains to be explored. The RNA...
Hepatitis B virus (HBV) infection is a major risk factor for hepatocellular carcinoma (HCC), but its pathogenic mechanism remains to be explored. The RNA N-methyladenosine (mA) reader, YTH (YT521-B homology) domain 2 (YTHDF2), plays a critical role in the HCC progression. However, the function and regulatory mechanisms of YTHDF2 in HBV-related HCC remain largely elusive. Here, we discovered that YTHDF2 O-GlcNAcylation was markedly increased upon HBV infection. O-GlcNAc transferase (OGT)-mediated O-GlcNAcylation of YTHDF2 on serine 263 enhanced its protein stability and oncogenic activity by inhibiting its ubiquitination. Mechanistically, YTHDF2 stabilized minichromosome maintenance protein 2 (MCM2) and MCM5 transcripts in an mA-dependent manner, thus promoting cell cycle progression and HBV-related HCC tumorigenesis. Moreover, targeting YTHDF2 O-GlcNAcylation by the OGT inhibitor OSMI-1 significantly suppressed HCC progression. Taken together, our findings reveal a new regulatory mechanism for YTHDF2 and highlight an essential role of YTHDF2 O-GlcNAcylation in RNA mA methylation and HCC progression. Further description of the molecular pathway has the potential to yield therapeutic targets for suppression of HCC progression due to HBV infection.
Topics: Humans; Carcinoma, Hepatocellular; Liver Neoplasms; Hepatitis B virus; RNA; RNA-Binding Proteins
PubMed: 36765030
DOI: 10.1038/s41392-023-01316-8 -
Emerging Microbes & Infections Dec 2021Hepatitis B virus (HBV) is a DNA virus with a complex life cycle that includes a reverse transcription step. HBV is poorly sensed by the immune system and frequently... (Review)
Review
Hepatitis B virus (HBV) is a DNA virus with a complex life cycle that includes a reverse transcription step. HBV is poorly sensed by the immune system and frequently establishes persistent infection that can cause chronic infection, the leading cause of liver cancer and cirrhosis worldwide. Recent mounting evidence has indicated the growing importance of RNA methylation (m6A modification) in viral replication, immune escape, and carcinogenesis. The value of m6A RNA modification for the prediction and clinical management of chronic HBV infection remains to be assessed. However, a number of studies indicate the important role of m6A-marked transcripts and factors of m6A machinery in managing HBV-related pathologies. In this review, we discuss the fundamental and potential clinical impact of m6A modifications on HBV infection and pathogenesis, as well as highlight the important molecular techniques and tools that can be used for studying RNA m6A methylome.
Topics: Animals; Hepatitis B; Hepatitis B virus; Host-Pathogen Interactions; Humans; Liver Neoplasms; Methylation
PubMed: 34767497
DOI: 10.1080/22221751.2021.2006580 -
Hepatology (Baltimore, Md.) Apr 2022
Topics: Demography; Hepatitis B virus; Mass Screening; United States
PubMed: 34951716
DOI: 10.1002/hep.32303 -
Signal Transduction and Targeted Therapy Sep 2023The pregenomic RNA (pgRNA) of hepatitis B virus (HBV) serves not only as a bicistronic message RNA to translate core protein (Cp) and DNA polymerase (Pol), but also as...
The pregenomic RNA (pgRNA) of hepatitis B virus (HBV) serves not only as a bicistronic message RNA to translate core protein (Cp) and DNA polymerase (Pol), but also as the template for reverse transcriptional replication of viral DNA upon packaging into nucleocapsid. Although it is well known that pgRNA translates much more Cp than Pol, the molecular mechanism underlying the regulation of Cp and Pol translation efficiency from pgRNA remains elusive. In this study, we systematically profiled HBV nucleocapsid- and pgRNA-associated cellular proteins by proteomic analysis and identified TIA-1-related protein (TIAR) as a novel cellular protein that binds pgRNA and promotes HBV DNA replication. Interestingly, loss- and gain-of-function genetic analyses showed that manipulation of TIAR expression did not alter the levels of HBV transcripts nor the secretion of HBsAg and HBeAg in human hepatoma cells supporting HBV replication. However, Ribo-seq and PRM-based mass spectrometry analyses demonstrated that TIAR increased the translation of Pol but decreased the translation of Cp from pgRNA. RNA immunoprecipitation (RIP) and pulldown assays further revealed that TIAR directly binds pgRNA at the 5' stem-loop (ε). Moreover, HBV replication or Cp expression induced the increased expression and redistribution of TIAR from the nucleus to the cytoplasm of hepatocytes. Our results thus imply that TIAR is a novel cellular factor that regulates HBV replication by binding to the 5' ε structure of pgRNA to tip the balance of Cp and Pol translation. Through induction of TIAR translocation from the nucleus to the cytoplasm, Cp indirectly regulates the Pol translation and balances Cp and Pol expression levels in infected hepatocytes to ensure efficient viral replication.
Topics: Humans; Cytoplasm; Hepatitis B virus; Proteomics; RNA
PubMed: 37699883
DOI: 10.1038/s41392-023-01573-7 -
Journal of Hepatology Dec 2021HBV consists of 9 major genotypes (A to I), 1 minor strain (designated J) and multiple subtypes, which may be associated with different clinical characteristics. As only...
BACKGROUND & AIMS
HBV consists of 9 major genotypes (A to I), 1 minor strain (designated J) and multiple subtypes, which may be associated with different clinical characteristics. As only cell lines expressing genotype D3 have been established, herein, we aimed to establish stable cell lines producing high-titer cell culture-generated HBV (HBVcc) of different genotypes and to explore their infectivity, virological features and responses to treatment.
METHODS
Stable cell lines producing high titers of HBV genotype A2, B2, C1, E, F1b and H were generated by transfecting plasmids containing a replication-competent 1.3x length HBV genome and an antibiotic marker into HepG2 cells that can support HBV replication. Clones with the highest levels of HBV DNA and/or HBeAg were selected and expanded for large-scale purification of HBVcc. HBVcc of different genotypes were tested in cells and a humanized chimeric mouse model.
RESULTS
HBVcc genotypes were infectious in mouse-passaged primary human hepatocytes (PXB cells) and responded differently to human interferon (IFN)-α with variable kinetics of reduction in HBV DNA, HBeAg and HBsAg. HBVcc of all genotypes were infectious in humanized chimeric mice but with variable kinetics of viremia and viral antigen production. Treatment of infected mice with human IFN-α resulted in modest and variable reductions of viremia and viral antigenemia. HBVcc passaged in humanized chimeric mice (HBVmp) infected PXB cells much more efficiently than that of the original HBVcc viral stock.
CONCLUSIONS
Herein, we generated stable cell lines producing HBV of various genotypes that are infectious in vitro and in vivo. We observe genotype-associated variations in viral antigen production, infection kinetics and responses to human IFN-α treatment in these models.
LAY SUMMARY
Stable cell lines producing high-titer cell culture-generated hepatitis B virus (HBV) of various genotypes were established. HBV genotypes showed stable infectivity in both in vitro and in vivo models, which are valuable tools for antiviral development.
Topics: Animals; Cell Culture Techniques; Disease Models, Animal; Genotype; Hepatitis B; Hepatitis B virus; Mice
PubMed: 34363922
DOI: 10.1016/j.jhep.2021.07.030 -
Hepatology (Baltimore, Md.) Jul 2021
Topics: DNA; Hepatitis B virus; RNA
PubMed: 33368408
DOI: 10.1002/hep.31689