scholarly journals RNA-Binding Motif Protein 24 (RBM24) Is Involved in Pregenomic RNA Packaging by Mediating Interaction between Hepatitis B Virus Polymerase and the Epsilon Element

2019 ◽  
Vol 93 (6) ◽  
Author(s):  
Yongxuan Yao ◽  
Bo Yang ◽  
Yingshan Chen ◽  
Hui Wang ◽  
Xue Hu ◽  
...  
Keyword(s):  
Hepatitis B Virus ◽  
Hepatitis B ◽  
Rna Binding ◽  
Binding Activity ◽  
Hbv Infection ◽  
Binding Motif ◽  
Independent Manner ◽  
Stem Loop ◽  
Hbv Replication ◽  
B Virus

ABSTRACTEncapsidation of pregenomic RNA (pgRNA) is a crucial step in hepatitis B virus (HBV) replication. Binding by viral polymerase (Pol) to the epsilon stem-loop (ε) on the 5′-terminal region (TR) of pgRNA is required for pgRNA packaging. However, the detailed mechanism is not well understood. RNA-binding motif protein 24 (RBM24) inhibits core translation by binding to the 5′-TR of pgRNA. Here, we demonstrate that RBM24 is also involved in pgRNA packaging. RBM24 directly binds to the lower bulge of ε via RNA recognition submotifs (RNPs). RBM24 also interacts with Pol in an RNA-independent manner. The alanine-rich domain (ARD) of RBM24 and the reverse transcriptase (RT) domain of Pol are essential for binding between RBM24 and Pol. In addition, overexpression of RBM24 increases Pol-ε interaction, whereas RBM24 knockdown decreases the interaction. RBM24 was able to rescue binding between ε and mutant Pol lacking ε-binding activity, further showing that RBM24 mediates the interaction between Pol and ε by forming a Pol-RBM24-ε complex. Finally, RBM24 significantly promotes the packaging efficiency of pgRNA. In conclusion, RBM24 mediates Pol-ε interaction and formation of a Pol-RBM24-ε complex, which inhibits translation of pgRNA and results in pgRNA packing into capsids/virions for reverse transcription and DNA synthesis.IMPORTANCEHepatitis B virus (HBV) is a ubiquitous human pathogen, and HBV infection is a major global health burden. Chronic HBV infection is associated with the development of liver diseases, including fulminant hepatitis, hepatic fibrosis, cirrhosis, and hepatocellular carcinoma. A currently approved vaccine can prevent HBV infection, and medications are able to reduce viral loads and prevent liver disease progression. However, current treatments rarely achieve a cure for chronic infection. Thus, it is important to gain insight into the mechanisms of HBV replication. In this study, we found that the host factor RBM24 is involved in pregenomic RNA (pgRNA) packaging and regulates HBV replication. These findings highlight a potential target for antiviral therapeutics of HBV infection.

scholarly journals Epitope–Paratope Interaction of a Neutralizing Human Anti-Hepatitis B Virus PreS1 Antibody That Recognizes the Receptor-Binding Motif

Vaccines ◽  
2021 ◽  
Vol 9 (7) ◽  
pp. 754
Author(s):  
Jisu Hong ◽  
Youngjin Choi ◽  
Yoonjoo Choi ◽  
Jiwoo Lee ◽  
Hyo Jeong Hong
Keyword(s):  
Hepatitis B Virus ◽  
Hepatitis B ◽  
Receptor Binding ◽  
Neutralizing Antibody ◽  
Hbv Infection ◽  
Binding Motif ◽  
Alanine Scanning Mutagenesis ◽  
B Virus ◽  
Complementarity Determining Regions

Hepatitis B virus (HBV) is a global health burden that causes acute and chronic hepatitis. To develop an HBV-neutralizing antibody that effectively prevents HBV infection, we previously generated a human anti-preS1 monoclonal antibody (1A8) that binds to genotypes A–D and validated its HBV-neutralizing activity in vitro. In the present study, we aimed to determine the fine epitope and paratope of 1A8 to understand the mechanism of HBV neutralization. We performed alanine-scanning mutagenesis on the preS1 (aa 19–34, genotype C) and the heavy (HCDR) and light (LCDR) chain complementarity-determining regions. The 1A8 recognized the three residues (Leu22, Gly23, and Phe25) within the highly conserved receptor-binding motif (NPLGFFP) of the preS1, while four CDR residues of 1A8 were critical in antigen binding. Structural analysis of the epitope–paratope interaction by molecular modeling revealed that Leu100 in the HCDR3, Ala50 in the HCDR2, and Tyr96 in the LCDR3 closely interacted with Leu22, Gly23, and Phe25 of the preS1. Additionally, we found that 1A8 also binds to the receptor-binding motif (NPLGFLP) of infrequently occurring HBV. The results suggest that 1A8 may broadly and effectively block HBV entry and thus have potential as a promising candidate for the prevention and treatment of HBV infection.

scholarly journals Hepatitis B virus polymerase restricts LINE-1 retrotransposition

2021 ◽  
Author(s):  
Yasuo Ariumi
Keyword(s):  
Hepatitis B Virus ◽  
Hepatitis B ◽  
Rna Binding ◽  
Rnase H ◽  
Ribonuclease H ◽  
Independent Manner ◽  
Cytoplasmic Rna ◽  
B Virus ◽  
Long Interspersed Element ◽  
L1 Retrotransposon

Long interspersed element-1 (LINE-1, L1) retrotransposon composes about 17% of the human genome. However, genetic and biochemical interactions between L1 and hepatitis B virus (HBV) remain poorly understood. In this study, we found that HBV restricts L1 mobility without inhibiting the L1 promoter activity. Notably, HBV polymerase (Pol) strongly inhibited L1 retrotransposition in a reverse transcriptase (RT)-independent manner. Indeed, the ribonuclease H (RNase H) domain was essential for inhibition of L1 retrotransposition. L1 ORF1p RNA-binding protein predominantly localized into cytoplasmic RNA granule termed P-body. However, HBV Pol sequestered L1 ORF1p from P-body and colocalized with L1 ORF1p in cytoplasm, when both proteins were co-expressed. Altogether, HBV Pol seems to restrict L1 mobility through a sequestration of L1 ORF1p from P-body. Thus, these results suggest a novel function or activity of HBV Pol in regulation of L1 retrotransposition.

Effect of zidovudine on hepatitis B virus (HBV) replication in patients with chronic HIV and HBV infection

1989 ◽  
Vol 9 ◽  
pp. S189
Author(s):  
P Marcellin ◽  
G Pialcux ◽  
PM Girard ◽  
N Bover ◽  
M Martinot ◽  
...  
Keyword(s):  
Hepatitis B Virus ◽  
Hepatitis B ◽  
Hbv Infection ◽  
Hbv Replication ◽  
B Virus

scholarly journals Characterization of Nuclear RNases That Cleave Hepatitis B Virus RNA near the La Protein Binding Site

2001 ◽  
Vol 75 (15) ◽  
pp. 6874-6883 ◽  
Author(s):  
Tilman Heise ◽  
Luca G. Guidotti ◽  
Francis V. Chisari
Keyword(s):  
Hepatitis B Virus ◽  
Hepatitis B ◽  
Rna Binding ◽  
Regulatory Element ◽  
Murine Cytomegalovirus ◽  
Mcmv Infection ◽  
Stem Loop ◽  
La Protein ◽  
Nuclear Extracts ◽  
B Virus

ABSTRACT Hepatitis B virus (HBV) RNA is downregulated by inflammatory cytokines induced in the liver by adoptively transferred HBV-specific cytotoxic T lymphocytes (CTLs) and during murine cytomegalovirus (MCMV) infections of the livers of HBV transgenic mice. The disappearance of HBV RNA is tightly associated with the cytokine-induced proteolytic cleavage of a previously defined HBV RNA-binding protein known as La autoantigen. La binds to a predicted stem-loop structure at the 5′ end of the posttranscriptional regulatory element of HBV RNA between nucleotides 1243 and 1333. In the present study, we searched for nuclear RNase activities that might be involved in HBV RNA decay. Nuclear extracts derived from control livers and CTL-injected and MCMV-infected livers were analyzed for the ability to cleave HBV RNA. Endonucleolytic activity that cleaved HBV RNA at positions 1269 to 1270 and 1271 to 1272, immediately 5′ of the stem-loop bound by the La protein (positions 1272 to 1293), was detected. Furthermore, we provide evidence that the cytokine-dependent downregulation of HBV RNA following MCMV infection is temporally associated with the upregulation of the endonucleolytic activity herein described. Collectively, these results suggest a model in which the steady-state HBV RNA content is controlled by the stabilizing influence of La and the destabilizing influence of nuclear RNase activities.

scholarly journals Hepatitis B Virus-Encoded MicroRNA Controls Viral Replication

2017 ◽  
Vol 91 (10) ◽  
Author(s):  
Xi Yang ◽  
Hongfeng Li ◽  
Huahui Sun ◽  
Hongxia Fan ◽  
Yaqi Hu ◽  
...  
Keyword(s):  
Hepatitis B Virus ◽  
Hepatitis B ◽  
Persistent Infection ◽  
Hepatoma Cell ◽  
Hbv Infection ◽  
Dependent Manner ◽  
Dna Virus ◽  
Hbv Replication ◽  
B Virus ◽  
Self Replication

ABSTRACT MicroRNAs (miRNAs) are a class of small, single-stranded, noncoding, functional RNAs. Hepatitis B virus (HBV) is an enveloped DNA virus with virions and subviral forms of particles that lack a core. It was not known whether HBV encodes miRNAs. Here, we identified an HBV-encoded miRNA (called HBV-miR-3) by deep sequencing and Northern blotting. HBV-miR-3 is located at nucleotides (nt) 373 to 393 of the HBV genome and was generated from 3.5-kb, 2.4-kb, and 2.1-kb HBV in a classic miRNA biogenesis (Drosha-Dicer-dependent) manner. HBV-miR-3 was highly expressed in hepatoma cell lines with an integrated HBV genome and HBV+ hepatoma tumors. In patients with HBV infection, HBV-miR-3 was released into the circulation by exosomes and HBV virions, and HBV-miR-3 expression had a positive correlation with HBV titers in the sera of patients in the acute phase of HBV infection. More interestingly, we found that HBV-miR-3 represses HBsAg, HBeAg, and replication of HBV. HBV-miR-3 targets the unique site of the HBV 3.5-kb transcript to specifically reduce HBc protein expression, levels of pregenomic RNA (pgRNA), and HBV replication intermediate (HBV-RI) generation but does not affect the HBV DNA polymerase level, thus suppressing HBV virion production (replication). This may explain the low levels of HBV virion generation with abundant subviral particles lacking core during HBV replication, which may contribute to the development of persistent infection in patients. Taken together, our findings shed light on novel mechanisms by which HBV-encoded miRNA controls the process of self-replication by regulating HBV transcript during infection. IMPORTANCE Hepatitis B is a liver infection caused by the hepatitis B virus (HBV) that can become a long-term, chronic infection and lead to cirrhosis or liver cancer. HBV is a small DNA virus that belongs to the hepadnavirus family, with virions and subviral forms of particles that lack a core. MicroRNA (miRNA), a small (∼22-nt) noncoding RNA, was recently found to be an important regulator of gene expression. We found that HBV encodes miRNA (HBV-miR-3). More importantly, we revealed that HBV-miR-3 targets its transcripts to attenuate HBV replication. This may contribute to explaining how HBV infection leads to mild damage in liver cells and the subsequent establishment/maintenance of persistent infection. Our findings highlight a mechanism by which HBV-encoded miRNA controls the process of self-replication by regulating the virus itself during infection and might provide new biomarkers for diagnosis and treatment of hepatitis B.

New insight in the pathobiology of hepatitis B virus infection

Gut ◽  
2012 ◽  
Vol 61 (Suppl 1) ◽  
pp. i6-i17 ◽  
Author(s):  
Maura Dandri ◽  
Stephen Locarnini
Keyword(s):  
Hepatitis B Virus ◽  
Hepatitis B ◽  
Immune Responses ◽  
Current Knowledge ◽  
Hbv Infection ◽  
Infected Hepatocyte ◽  
Hbv Replication ◽  
Chronic Hepatitis B Virus ◽  
B Virus ◽  
Important Host

Chronic hepatitis B virus (HBV) infection remains a major health burden and the main risk factor for the development of hepatocellular carcinoma worldwide. However, HBV is not directly cytopathic and liver injury appears to be mostly caused by repeated attempts of the host's immune responses to control the infection. Recent studies have shown that the unique replication strategy adopted by HBV enables it to survive within the infected hepatocyte while complex virus–host interplays ensure the virus is able to fulfil its replication requirements yet is still able to evade important host antiviral innate immune responses. Clearer understanding of the host and viral mechanisms affecting HBV replication and persistence is necessary to design more effective therapeutic strategies aimed at improving the management of patients with chronic HBV infection to eventually achieve viral eradication. This article focuses on summarising the current knowledge of factors influencing the course of HBV infection, giving emphasis on the use of novel assays and quantitative serological and intrahepatic biomarkers as tools for predicting treatment response and disease progression.

scholarly journals Sirtuins as Potential Therapeutic Targets for Hepatitis B Virus Infection

2021 ◽  
Vol 8 ◽  
Author(s):  
Fanyun Kong ◽  
Qi Li ◽  
Fulong Zhang ◽  
Xiaocui Li ◽  
Hongjuan You ◽  
...  
Keyword(s):  
Hepatitis B Virus ◽  
Hepatitis B ◽  
Histone Deacetylases ◽  
Molecular Mechanisms ◽  
Hbv Infection ◽  
Viral Propagation ◽  
Therapeutic Modalities ◽  
Cellular Processes ◽  
Hbv Replication ◽  
B Virus

Sirtuins (SIRTs) are well-known histone deacetylases that are capable of modulating various cellular processes in numerous diseases, including the infection of hepatitis B virus (HBV), which is one of the primary pathogenic drivers of liver cirrhosis and hepatocellular carcinoma. Mounting evidence reveals that HBV can alter the expression levels of all SIRT proteins. In turn, all SIRTs regulate HBV replication via a cascade of molecular mechanisms. Furthermore, several studies suggest that targeting SIRTs using suitable drugs is a potential treatment strategy for HBV infection. Here, we discuss the molecular mechanisms associated with SIRT-mediated upregulation of viral propagation and the recent advances in SIRT-targeted therapy as potential therapeutic modalities against HBV infection.

scholarly journals Interactions between hepatitis B virus and aflatoxin B1: effects on p53 induction in HepaRG cells

2012 ◽  
Vol 93 (3) ◽  
pp. 640-650 ◽  
Author(s):  
Myriam Lereau ◽  
Doriane Gouas ◽  
Stéphanie Villar ◽  
Ahmad Besaratinia ◽  
Agnès Hautefeuille ◽  
...  
Keyword(s):  
Risk Factors ◽  
Dna Damage ◽  
Hepatitis B Virus ◽  
Hepatitis B ◽  
Cell Line ◽  
Hbv Infection ◽  
Hbv Replication ◽  
Heparg Cell Line ◽  
Heparg Cells ◽  
B Virus

Infection by hepatitis B virus (HBV) and dietary exposure to aflatoxin B1 (AFB1) are the main risk factors for the development of chronic liver disease and hepatocellular carcinoma (HCC). How these factors cooperate is still largely unknown. AFB1 activation leads to DNA adduction and mutagenesis, with a specific mutation at codon 249 in TP53 (p.R249S). So far, only limited studies have addressed the effects of AFB1 on HBV replication. We have analysed the effects of both risk factors on p53 induction during HBV infection in HepaRG, a cell line with hepatocyte-like morphology that metabolizes AFB1 and supports HBV infection. Exposure to AFB1 up to 5 µM induced a downregulation of HBV replication after 48 h, as measured by a decrease in viral antigens in the culture medium (HBsAg, HBeAg and large envelope protein) and in intracellular levels of HBV transcripts, DNA and HBsAg. Conversely, HBV infection did not significantly modify AFB1-DNA adduct formation or repair as assessed by immunodot-blot assay, and the induction of p53 in response to AFB1 was similar in infected and non-infected HepaRG cells. Overall, our results suggest that AFB1 exposure decreases HBV replication, whereas DNA damage by AFB1 and subsequent p53 induction is not affected by the presence of the virus. Thus, in HepaRG cell line, AFB1 and HBV do not cooperate to increase DNA damage by AFB1. Further studies on the effects of both factors in a context of chronicity are needed to better understand synergistic effects.

scholarly journals TIP60 Complex Inhibits Hepatitis B Virus Transcription

2018 ◽  
Vol 92 (6) ◽  
Author(s):  
Hironori Nishitsuji ◽  
Saneyuki Ujino ◽  
Keisuke Harada ◽  
Kunitada Shimotohno
Keyword(s):  
Hepatitis B Virus ◽  
Hepatitis B ◽  
Molecular Mechanism ◽  
Chromatin Structure ◽  
Core Promoter ◽  
Hbv Infection ◽  
Host Factors ◽  
Major Health Problem ◽  
Hbv Replication ◽  
B Virus

ABSTRACTHepatitis B virus (HBV) is a global major health problem, with over one million deaths annually caused by chronic liver damage. Understanding host factors that modulate HBV replication may aid the development of anti-HBV therapies. Our recent genome-wide small interfering RNA screen using recombinant HBV demonstrated that TIP60 inhibited HBV infection. Here, we show that TIP60 complex contributes to anti-HBV defense. The TIP60 complex bound to the HBV promoter and suppressed HBV transcription driven by the precore/core promoter. The silencing of EP400, TRRAP, BAF53a, RUVBL1, and RUVBL2, which form the TIP60 complex, also resulted in increased HBV transcription. These results contribute to our enhanced understanding of the molecular mechanism of HBV transcription associated with the chromatin structure of HBV covalently closed circular DNA (cccDNA). Exploiting these intrinsic cellular defenses might help develop new anti-HBV agents.IMPORTANCEInvestigating the molecular mechanism of HBV replication is important to understand the persistent nature of HBV infection and to aid the development of new HBV agents, which are currently limited to HBV polymerase inhibitors. Previously, we developed a new reporter HBV. By screening host factors using this recombinant virus, we identified several gene products that regulate HBV infection, including TIP60. Here, we showed that TIP60, a catalytic subunit of the NuA4 complex, inhibited HBV replication. Depletion of TIP60 increased the level of HBV mRNA. Moreover, TIP60 localized in the HBV cccDNA chromatin complex catalyzed the acetylation of histone H4 to recruit Brd4. These results suggest that TIP60, in concert with other cellular factors, plays an important role in the regulation of the HBV chromatin structure by acting as a critical component of the intrinsic antiviral defense, which sheds new light on the regulation of HBV replication.

RNA Helicase DDX17 inhibits Hepatitis B Virus Replication by Blocking Viral Pregenomic RNA Encapsidation

2021 ◽  
Author(s):  
Richeng Mao ◽  
Minhui Dong ◽  
Zhongliang Shen ◽  
Hu Zhang ◽  
Yuanjie Liu ◽  
...  
Keyword(s):  
Hepatitis B Virus ◽  
Hepatitis B ◽  
Rna Degradation ◽  
Viral Rna ◽  
Health Concern ◽  
Dependent Manner ◽  
Stem Loop ◽  
Hbv Replication ◽  
Dead Box ◽  
B Virus

DDX17 is a member of the DEAD-Box helicase family proteins involved in cellular RNA folding, splicing, and translation. It has been reported that DDX17 serves as a co-factor of host zinc finger antiviral protein (ZAP)-mediated retroviral RNA degradation and exerts direct antiviral function against Raft Valley Fever Virus though binding to specific stem-loop structures of viral RNA. Intriguingly, we have previously shown that ZAP inhibits Hepatitis B virus (HBV) replication through promoting viral RNA decay, and the ZAP-responsive element (ZRE) of HBV pregenomic RNA (pgRNA) contains a stem-loop structure, specifically epsilon, which serves as the packaging signal for pgRNA encapsidation. In this study, we demonstrated that the endogenous DDX17 is constitutively expressed in human hepatocyte-derived cells but dispensable for ZAP-mediated HBV RNA degradation. However, DDX17 was found to inhibit HBV replication primarily by reducing the level of cytoplasmic encapsidated pgRNA in a helicase-dependent manner. Immunofluorescence assay revealed that DDX17 could gain access to cytoplasm from nucleus in the presence of HBV RNA. In addition, RNA immunoprecipitation and electrophoretic mobility shift assays demonstrated that the enzymatically active DDX17 competes with HBV polymerase to bind to pgRNA at the 5’ epsilon motif. In summary, our study suggests that DDX17 serves as an intrinsic host restriction factor against HBV through interfering with pgRNA encapsidation. IMPORTANCE Hepatitis B virus (HBV) chronic infection, a long-studied but yet incurable disease, remains a major public health concern worldwide. Given that HBV replication cycle highly depends on host factors, deepening our understanding of the host-virus interaction is thus of great significance in the journey of finding a cure. In eukaryotic cells, RNA helicases of DEAD-box family are highly conserved enzymes involved in diverse processes of cellular RNA metabolism. Emerging data have shown that DDX17, a typical member of DEAD box family, functions as an antiviral factor through interacting with viral RNA. In this study, we, for the first time, demonstrate that DDX17 inhibits HBV through blocking the formation of viral replication complex, which not only broadens the antiviral spectrum of DDX17, but also provides new insight into the molecular mechanism of DDX17-mediated virus-host interaction.

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