scholarly journals A dual role for SAMHD1 in regulating HBV cccDNA and RT-dependent particle genesis

2019 ◽  
Vol 2 (2) ◽  
pp. e201900355 ◽  
Author(s):  
Peter AC Wing ◽  
Tamara Davenne ◽  
Jochen Wettengel ◽  
Alvina G Lai ◽  
Xiaodong Zhuang ◽  
...  
Keyword(s):  
Hepatitis B ◽  
Fold Increase ◽  
Dual Role ◽  
Positive Role ◽  
Infectious Particle ◽  
Circular Dna ◽  
Hbv Cccdna ◽  
B Virus ◽  
Localization Signal ◽  
Deoxyribonucleoside Triphosphate

Chronic hepatitis B is one of the world’s unconquered diseases with more than 240 million infected subjects at risk of developing liver disease and hepatocellular carcinoma. Hepatitis B virus reverse transcribes pre-genomic RNA to relaxed circular DNA (rcDNA) that comprises the infectious particle. To establish infection of a naïve target cell, the newly imported rcDNA is repaired by host enzymes to generate covalently closed circular DNA (cccDNA), which forms the transcriptional template for viral replication. SAMHD1 is a component of the innate immune system that regulates deoxyribonucleoside triphosphate levels required for host and viral DNA synthesis. Here, we show a positive role for SAMHD1 in regulating cccDNA formation, where KO of SAMHD1 significantly reduces cccDNA levels that was reversed by expressing wild-type but not a mutated SAMHD1 lacking the nuclear localization signal. The limited pool of cccDNA in infectedSamhd1KO cells is transcriptionally active, and we observed a 10-fold increase in newly synthesized rcDNA-containing particles, demonstrating a dual role for SAMHD1 to both facilitate cccDNA genesis and to restrict reverse transcriptase-dependent particle genesis.

scholarly journals Mechanism of Hepatitis B Virus cccDNA Formation

Viruses ◽  
2021 ◽  
Vol 13 (8) ◽  
pp. 1463
Author(s):  
Lei Wei ◽  
Alexander Ploss
Keyword(s):  
Hepatitis B Virus ◽  
Hepatitis B ◽  
Medical Problem ◽  
Circular Dna ◽  
Critical Step ◽  
Hbv Cccdna ◽  
Double Stranded Dna ◽  
Cellular Environment ◽  
B Virus ◽  
Comprehensive Picture

Hepatitis B virus (HBV) remains a major medical problem affecting at least 257 million chronically infected patients who are at risk of developing serious, frequently fatal liver diseases. HBV is a small, partially double-stranded DNA virus that goes through an intricate replication cycle in its native cellular environment: human hepatocytes. A critical step in the viral life-cycle is the conversion of relaxed circular DNA (rcDNA) into covalently closed circular DNA (cccDNA), the latter being the major template for HBV gene transcription. For this conversion, HBV relies on multiple host factors, as enzymes capable of catalyzing the relevant reactions are not encoded in the viral genome. Combinations of genetic and biochemical approaches have produced findings that provide a more holistic picture of the complex mechanism of HBV cccDNA formation. Here, we review some of these studies that have helped to provide a comprehensive picture of rcDNA to cccDNA conversion. Mechanistic insights into this critical step for HBV persistence hold the key for devising new therapies that will lead not only to viral suppression but to a cure.

scholarly journals Hepatitis B Core-Related Antigen as Surrogate Biomarker of Intrahepatic Hepatitis B Virus Covalently-Closed-Circular DNA in Patients with Chronic Hepatitis B: A Meta-Analysis

Diagnostics ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. 187
Author(s):  
Gian Paolo Caviglia ◽  
Angelo Armandi ◽  
Chiara Rosso ◽  
Davide Giuseppe Ribaldone ◽  
Rinaldo Pellicano ◽  
...  
Keyword(s):  
Hepatitis B Virus ◽  
Hepatitis B ◽  
Hepatitis B Surface Antigen ◽  
Meta Analysis ◽  
Circular Dna ◽  
Non Invasive ◽  
Hbv Cccdna ◽  
B Virus ◽  
Chronic Hbv ◽  
Intrahepatic Hbv

Hepatitis B virus (HBV) covalently-closed-circular (ccc)DNA is the key molecule responsible for viral persistence within infected hepatocytes. The evaluation of HBV cccDNA is crucial for the management of patients with chronic HBV infection and for the personalization of treatment. However, the need for liver biopsy is the principal obstacle for the assessment of intrahepatic HBV cccDNA. In the last decade, several studies have investigated the performance of hepatitis B core-related antigen (HBcrAg) as a surrogate of HBV cccDNA amount in the liver. In this meta-analysis, we collected 14 studies (1271 patients) investigating the correlation between serum HBcrAg and intrahepatic HBV cccDNA. Serum HBcrAg showed a high correlation with intrahepatic HBV cccDNA (r = 0.641, 95% confidence interval (CI) 0.510–0.743, p < 0.001). In a head-to-head comparison, we observed that the performance of HBcrAg was significantly superior to that of hepatitis B surface antigen (r = 0.665 vs. r = 0.475, respectively, p < 0.001). Subgroup analysis showed that the correlation between HBcrAg and intrahepatic HBV cccDNA was high, both in hepatitis B e antigen-positive and -negative patients (r = 0.678, 95% CI 0.403–0.840, p < 0.001, and r = 0.578, 95% CI 0.344–0.744, p < 0.001, respectively). In conclusion, the measurement of serum HBcrAg qualifies as a reliable non-invasive surrogate for the assessment of an intrahepatic HBV cccDNA reservoir.

scholarly journals How to Clear HBV cccDNA: CRISPR/Cas9 Might Be Promising

2017 ◽  
Author(s):  
Yan Qiu ◽  
Ying Liu ◽  
Wen Ren ◽  
Jing Ren
Keyword(s):  
Chronic Hepatitis ◽  
Hepatitis B Virus ◽  
Hepatitis B ◽  
Chronic Hepatitis B ◽  
Health Concern ◽  
Liver Carcinoma ◽  
Major Health ◽  
Circular Dna ◽  
Hbv Cccdna ◽  
B Virus

BACKGROUND: Chronic hepatitis B infected with Hepatitis B virus remains a major health concern worldwide. Despite standard interferon-&alpha; and nucleotide analogues have been shown to reduce the deterioration of liver disease among chronic hepatitis B patients, covalently closed circular DNA was still difficult to eradicate. METHODS: A literature search of Pubmed and Web of science was performed with the following key words: &lsquo;CRISPR&rsquo;, &lsquo;CRISPR/Cas9&rsquo;, &lsquo;hepatitis B&rsquo;, &lsquo;HBV&rsquo;, &lsquo;chronic hepatitis B&rsquo; and &lsquo;HBV cccDNA&rsquo;. The information about CRISPR/Cas9 for the treatment of HBV cccDNA or hepatitis B was reviewed. RESULTS: CRISPR/Cas9 could treat hepatitis B through suppressing or clearing HBV cccDNA with different gRNAs. CONCLUSION: With the emergence of CRISPR/Cas9 (the RNA-guided clustered regulatory interspaced short palindromic repeats, CRISPR) editing technology, clearance of hepatitis B virus and better prevention of liver carcinoma seemed to be possible.

scholarly journals Identification of Disubstituted Sulfonamide Compounds as Specific Inhibitors of Hepatitis B Virus Covalently Closed Circular DNA Formation

2012 ◽  
Vol 56 (8) ◽  
pp. 4277-4288 ◽  
Author(s):  
Dawei Cai ◽  
Courtney Mills ◽  
Wenquan Yu ◽  
Ran Yan ◽  
Carol E. Aldrich ◽  
...  
Keyword(s):  
Cell Culture ◽  
Hepatitis B Virus ◽  
Hepatitis B ◽  
Polymerase Activity ◽  
Circular Dna ◽  
Drug Candidates ◽  
Covalently Closed Circular Dna ◽  
Hbv Cccdna ◽  
B Virus

ABSTRACTHepatitis B virus (HBV) covalently closed circular DNA (cccDNA) plays a central role in viral infection and persistence and is the basis for viral rebound after the cessation of therapy, as well as the elusiveness of a cure even after extended treatment. Therefore, there is an urgent need for the development of novel therapeutic agents that directly target cccDNA formation and maintenance. By employing an innovative cell-based cccDNA assay in which secreted HBV e antigen is a cccDNA-dependent surrogate, we screened an in-house small-molecule library consisting of 85,000 drug-like compounds. Two structurally related disubstituted sulfonamides (DSS), termed CCC-0975 and CCC-0346, emerged and were confirmed as inhibitors of cccDNA production, with low micromolar 50% effective concentrations (EC50s) in cell culture. Further mechanistic studies demonstrated that DSS compound treatment neither directly inhibited HBV DNA replication in cell culture nor reduced viral polymerase activity in thein vitroendogenous polymerase assay but synchronously reduced the levels of HBV cccDNA and its putative precursor, deproteinized relaxed circular DNA (DP-rcDNA). However, DSS compounds did not promote the intracellular decay of HBV DP-rcDNA and cccDNA, suggesting that the compounds interfere primarily with rcDNA conversion into cccDNA. In addition, we demonstrated that CCC-0975 was able to reduce cccDNA biosynthesis in duck HBV-infected primary duck hepatocytes. This is the first attempt, to our knowledge, to identify small molecules that target cccDNA formation, and DSS compounds thus potentially serve as proof-of-concept drug candidates for development into therapeutics to eliminate cccDNA from chronic HBV infection.

scholarly journals New Insights on Molecular Mechanism of Hepatitis B Virus Covalently Closed Circular DNA Formation

Cells ◽  
2020 ◽  
Vol 9 (11) ◽  
pp. 2430
Author(s):  
Alexander L. Marchetti ◽  
Haitao Guo
Keyword(s):  
Hepatitis B Virus ◽  
Hepatitis B ◽  
Cellular Functions ◽  
Circular Dna ◽  
Dna Repair Mechanisms ◽  
Covalently Closed Circular Dna ◽  
Hbv Cccdna ◽  
B Virus ◽  
Repair Mechanisms ◽  
Open Circular

The chronic factor of the Hepatitis B Virus (HBV), specifically the covalently closed circular DNA (cccDNA), is a highly stable and active viral episomal genome established in the livers of chronic hepatitis B patients as a constant source of disease. Being able to target and eliminate cccDNA is the end goal for a genuine cure for HBV. Yet how HBV cccDNA is formed from the viral genomic relaxed circular DNA (rcDNA) and by what host factors had been long-standing research questions. It is generally acknowledged that HBV hijacks cellular functions to turn the open circular DNA conformation of rcDNA into cccDNA through DNA repair mechanisms. With great efforts from the HBV research community, there have been several recent leaps in our understanding of cccDNA formation. It is our goal in this review to analyze the recent reports showing evidence of cellular factor’s involvement in the molecular pathway of cccDNA biosynthesis.

scholarly journals Revisiting Hepatitis B Virus: Challenges of Curative Therapies

2019 ◽  
Vol 93 (20) ◽  
Author(s):  
Jianming Hu ◽  
Ulrike Protzer ◽  
Aleem Siddiqui
Keyword(s):  
Hepatitis B Virus ◽  
Hepatitis B ◽  
Reverse Transcriptase ◽  
Reverse Transcriptase Activity ◽  
Viral Gene ◽  
Major Health Problem ◽  
Circular Dna ◽  
Infected Hepatocyte ◽  
Hbv Cccdna ◽  
B Virus

ABSTRACT With a yearly death toll of 880,000, hepatitis B virus (HBV) remains a major health problem worldwide, despite an effective prophylactic vaccine and well-tolerated, effective antivirals. HBV causes chronic hepatitis, fibrosis, cirrhosis, and hepatocellular carcinoma. The viral genome persists in infected hepatocytes even after long-term antiviral therapy, and its integration, though no longer able to support viral replication, destabilizes the host genome. HBV is a DNA virus that utilizes a virus-encoded reverse transcriptase to convert an RNA intermediate, termed pregenomic RNA, into the relaxed circular DNA genome, which is subsequently converted into a covalently closed circular DNA (cccDNA) in the host cell nucleus. cccDNA is maintained in the nucleus of the infected hepatocyte as a stable minichromosome and functions as the viral transcriptional template for the production of all viral gene products, and thus, it is the molecular basis of HBV persistence. The nuclear cccDNA pool can be replenished through recycling of newly synthesized, DNA-containing HBV capsids. Licensed antivirals target the HBV reverse transcriptase activity but fail to eliminate cccDNA, which would be required to cure HBV infection. Elimination of HBV cccDNA is so far only achieved by antiviral immune responses. Thus, this review will focus on possible curative strategies aimed at eliminating or crippling the viral cccDNA. Newer insights into the HBV life cycle and host immune response provide novel, potentially curative therapeutic opportunities and targets.

scholarly journals Correlation of HBcrAg with Intrahepatic Hepatitis B Virus Total DNA and Covalently Closed Circular DNA in HBeAg-Positive Chronic Hepatitis B Patients

2018 ◽  
Vol 57 (1) ◽  
Author(s):  
Lin Wang ◽  
Xi Cao ◽  
Zhenzi Wang ◽  
Yuhua Gao ◽  
Juan Deng ◽  
...  
Keyword(s):  
Chronic Hepatitis ◽  
Hepatitis B Virus ◽  
Hepatitis B ◽  
Hbv Dna ◽  
Circular Dna ◽  
Hbv Cccdna ◽  
B Virus ◽  
Positive Chronic Hepatitis ◽  
Total Dna ◽  
Intrahepatic Hbv

ABSTRACT The purpose of this study was to explore the correlations of serum hepatitis B core-related antigen (HBcrAg) with intrahepatic Hepatitis B virus (HBV) covalently closed circular DNA (cccDNA) and HBV total DNA in hepatitis B e antigen (HBeAg)-positive chronic hepatitis B (CHB) patients. Serum HBcrAg and other parameters, including HBV DNA, HBV RNA, HBeAg, hepatitis B surface antigen (HBsAg), hepatitis B core antibody (anti-HBc), alanine aminotransferase (ALT), and aspartate aminotransferase (AST) were quantitatively measured at baseline and follow-up time points. Intrahepatic HBV cccDNA and total DNA were quantitatively detected at baseline and 96 weeks. Grading of liver necroinflammation and staging of hepatic fibrosis were assessed at baseline and 96 weeks. Correlations between serum HBcrAg and other parameters were analyzed by Pearson’s correlation analysis. The results showed that pretreatment HBcrAg correlated significantly with HBV total DNA levels (r = 0.328, P = 0.003) in 82 CHB patients, and, after removing three outliers, with intrahepatic HBV cccDNA (r = 0.323, P = 0.004; n = 79). Serum HBcrAg correlated better with HBV cccDNA in patients with lower levels of serum HBV DNA (stratified by 7 log IU/ml of HBV DNA; r = 0.656, P = 0.003 versus r = −0.02, P = 0.866). Significant inverse correlations were found between HBcrAg and grade of liver necroinflammation (r = −0.245, P = 0.037), stage of hepatic fibrosis (r = −0.360, P = 0.002) at baseline. Serum HBcrAg presented significant correlation with intrahepatic HBV cccDNA in patients with HBeAg seroconversion at 96 weeks (r = 0.622, P = 0.006). The decrease in HBcrAg showed significant correlation with the decrease in HBV cccDNA after 96-week NA therapy (r = 0.282, P = 0.043). Serum HBcrAg also correlated significantly with other serum markers at baseline and 96 weeks of NA therapy. In conclusion, baseline HBcrAg and its decreased value were significantly correlated with the corresponding intrahepatic HBV cccDNA.

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