Formation of the pool of covalently closed circular viral DNA in hepadnavirus-infected cells

Tuttleman, J S; Pourcel, Christine; Summers, Jesse

doi:10.1016/0092-8674(86)90602-1

Cited by 609 publications

(531 citation statements)

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“…cccDNA, which is the viral template for HBV replication in the maintenance of chronic infection, and the correlation between these two factors has been previously addressed. 6,7,28 In addition, qHBsAg has a clinical role in predicting the response to antiviral therapy in patients undergoing PEG-IFN treatment. A 1 log IU/mL drop in qHBsAg at week 24 of therapy was shown to predict SVR (NPV ¼ 97%, PPV ¼ 92%), and a low qHBsAg level at week 48 with an on-treatment decline > 1 log IU/mL was shown to be associated with sustained HBsAg clearance.…”

Section: Discussionmentioning

confidence: 99%

Quantitative hepatitis B surface antigen and hepatitis B e antigen titers in prediction of treatment response to entecavir

et al. 2011

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Quantitative hepatitis B surface antigen (qHBsAg) and quantitative hepatitis B e antigen (qHBeAg) titers are emerging as useful tools for measuring viral loads and for predicting the virological response (VR) and serological response (SR) to pegylated interferon therapy. However, the clinical utility of these assays in patients taking entecavir (ETV) is largely unknown. Treatment-naive patients with chronic hepatitis B (CHB) who were taking ETV for 2 years were enrolled. The qHBsAg and qHBeAg levels were serially measured with the Architect assay. From 95 patients, 60.0% of whom were hepatitis B e antigen-positive [HBeAg(1)], 475 samples were analyzed. The median baseline log hepatitis B virus (HBV) DNA, log qHBsAg, and log qHBeAg values were 6.73 copies/mL (4.04-9.11 copies/mL), 3.58 IU/mL (1.17-5.10 IU/ mL), and 1.71 Paul Ehrlich (PE) IU/mL (20.64 to 2.63 PE IU/mL), respectively. For the prediction of VR (HBV DNA < 60 copies/mL at 24 months) in HBeAg(1) patients, baseline alanine aminotransferase (P 5 0.013), HBV DNA (P 5 0.040), and qHBsAg levels (P 5 0.033) were significant. For the prediction of VR, the area under the curve for the baseline log qHBsAg level was 0.823 (P < 0.001); a cutoff level of 3.98 IU/mL (9550 IU/mL on a nonlogarithmic scale) yielded the highest predictive value with a sensitivity of 86.8% and a specificity of 78.9%. As for SR (HBeAg loss at 24 months), the reduction of qHBeAg was significantly greater in the SR(1) group versus the SR(2) group. The sensitivity and specificity were 75.0% and 89.8%, respectively, with a decline of 1.00 PE IU/mL at 6 months. With ETV therapy, the correlation between HBV DNA and qHBsAg peaked at 6 months in HBeAg(1) patients. Conclusion: Both qHBsAg and qHBeAg decreased significantly with ETV therapy. The baseline qHBsAg levels and the on-treatment decline of qHBeAg in HBeAg(1) patients were proven to be highly useful in predicting VR and SR, respectively. The determination of qHBsAg and qHBeAg can help us to select the appropriate strategy for the management of patients with CHB. However, the dynamic interplay between qHBsAg, qHBeAg, and HBV DNA during antiviral therapy remains to be elucidated. (HEPATOLOGY 2011;53:1486-1493 C hronic infection with hepatitis B virus (HBV) is a worldwide health problem, with more than 400 million people thought to be infected.Moreover, these patients are at increased risk for disease progression to cirrhosis and hepatocellular carcinoma. 1 Large cohort studies have shown that elevated levels of Abbreviations: ALT, alanine aminotransferase; anti-HBs, antibody to hepatitis B surface antigen; AUC, area under the curve; AUROC, area under the receiver operating characteristic

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Section: Discussionmentioning

confidence: 99%

Quantitative hepatitis B surface antigen and hepatitis B e antigen titers in prediction of treatment response to entecavir

et al. 2011

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“…However, it results in the activation of intracellular pathways translocating capsids from cytoplasm to nucleus. 39,40 Besides these intracellular changes in the localization of viral proteins as a result of MUT1 and -2, the extracellular ratio between globular and filamentous particles was changed. When MUT1 and -2 were transfected, the relative amount of globular particles was reduced compared with filaments.…”

Section: Discussionmentioning

confidence: 99%

The Pre-S region determines the intracellular localization and appearance of hepatitis B virus

et al. 1999

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The functional role of the hepatitis B virus (HBV) pre-S region for assembly and appearance of the virus is not completely understood. In this study, 3 natural-occurring mutants were investigated. Three mutants of the pre-S region-a point mutation in the CCAAT box (MUT1), a 6-bp deletion (MUT2) 3Ј of the CCAAT box, and a 153-bp deletion (MUT3) in the preS2 domain-were cloned alone or in combinations in replication-competent HBV plasmids and transfected in hepatoma cells. The impact on HBV assembly and appearance was studied by Northern Blot, primer extension analysis, immunofluorescence studies, enzyme-linked immunosorbent assay, and electron microscopy. An inversed ratio of pre-S/S mRNA transcripts compared with wild-type (wt) HBV was found when either MUT1 or -2 were included into the plasmid. Intracellular localization with both mutants showed retention of large S-protein in the endoplasmic reticulum and nuclear accumulation of core protein. The extracellular amount of S-protein was reduced with MUT1 and -2 or combinations in which 1 of the mutants was included. However, the extracellular appearance of viral products was comparable with wtHBV. In contrast, MUT3 showed major changes. Virion-like particles had a fried-egg, and filaments a screw-like appearance. The S-promoter mutations MUT1 and MUT2 correlated with viral retention. MUT3 leads to malformed viral particles. Therefore, different regions in the pre-S domain are essential to determine the intracellular localization and extracellular appearance of HBV, and might contribute to the prognosis of chronic HBV infection. (HEPATOLOGY 1999; 30:517-525.)The hepatitis B virus (HBV) is the smallest DNA virus known to be pathogenic for humans. The HBV is a member of the hepadnavirus family, showing a close host tropism. The genome of the HBV consists of a small circular DNA of 3.2 kb in length. Despite its small size, the HBV genome contains 4 open reading frames partly overlapping and generating at least 7 viral gene products. The 4 open reading frames are under the transcriptional control of 4 promoters (preS1, S, C, and X promoter) and 2 enhancer (enhancer I and II) elements. [1][2][3] The envelope gene of the HBV is controlled by 2 different promoters: the pre-S-and the S-promoter, which regulate transcription of a 2.4-and a 2.1-kb mRNA, respectively. The pre-S-promoter is located 5Ј of the first in frame ATG of the large (pre-S1) envelope protein. The S-promoter is found in the coding region of the pre-S gene and is a TATA-less promoter. Mainly, 2 factors control the activity of the Spromoter: Sp 1 and NF-Y. 4-7 NF-Y binds to the so-called CCAAT box and is especially important for the regulation of the S-gene controlling the ratio between the pre-S and S mRNA. 4,8 The 2 mRNAs transcribed from the S-gene code for 3 S-proteins (small, middle, and large) sharing the 226 amino acids at the C-terminus. Translation of the small S-protein starts at the third in-frame ATG of the S-gene, while the other 2 proteins start at the first and second ATG. However, some sub...

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“…6 To establish a sufficient pool of nuclear cccDNA, some of the newly synthesized viral DNAs need to be retransported to the nucleus of the infected hepatocyte. 7 Therefore, the replicative forms of viral DNA are also precursors to cccDNA.…”

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confidence: 99%

Increased hepatocyte turnover and inhibition of woodchuck hepatitis B virus replication by adefovirIn vitro do not lead to reduction of the closed circular DNA

et al. 2000

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The aim of this study was to evaluate the inhibitory effect of the nucleotide analogue adefovir on woodchuck hepatitis B virus (WHV) replication and, in particular, to determine whether the pool of covalently closed circular DNA (cccDNA) could be reduced by adefovir treatment in primary cultures of woodchuck hepatocytes isolated from a chronic carrier. Strong reduction of WHV-DNA synthesis (90%) and secretion (up to 98%) was observed with all 3 doses of adefovir used (1, 10, and 100 mol/L), whereas in the absence of the drug, high amounts of viral particles were continuously secreted in the culture medium until the end of the study (27 days). Secretion of envelope proteins and viral RNA levels remained constant both in the adefovirtreated and -untreated cultures for the entire course of the study. Intracellular core protein levels declined by approximately 50% in all the cultures, independent of adefovir treatment. There was no indication of cccDNA loss in the adefovir-treated hepatocyte cultures even when cell turnover was induced for 14 days by the addition of epidermal growth factor (EGF) to the culture medium. Our data show that adefovir has a very strong inhibitory effect on WHV-DNA synthesis in chronically infected primary hepatocyte cultures and indicate that cccDNA is a very stable molecule that appears to be efficiently transmitted to the dividing hepatocytes. (HEPATOLOGY 2000;32:139-146.)Persistent infection with hepatitis B virus (HBV) continues to be a major health problem as it is associated with various degrees of liver damage, cirrhosis, and hepatocellular carcinoma. Despite the existence of an effective vaccine, more than 350 million people are infected worldwide. 1,2 Current treatment regimens primarily rely on interferon alfa therapy. However, interferon treatment is associated with a variety of side effects and has been successful in only approximately one third of the patients, being very poorly effective in individuals with perinatally acquired HBV infection. In recent years, a variety of new anti-HBV agents have been developed, and these are currently evaluated in clinical trials. 3,4 Because HBV replication proceeds through reverse transcription, treatment with inhibitors of HBV reverse transcriptase is a very attractive option.During hepadnavirus infection, the relaxed circular partially double stranded DNA genome is transported to the nucleus of the hepatocyte, where it is converted into a covalently closed circular molecule, named cccDNA, which serves as template for the transcription of all viral RNAs. 5 The synthesis of the new relaxed circular viral DNA genome is mediated by the viral P-protein, which has reverse transcriptase and DNA-dependent DNA polymerase activity. Synthesis of the viral DNA takes place in the cytoplasm of the hepatocytes within immature nucleocapsids. 6 To establish a sufficient pool of nuclear cccDNA, some of the newly synthesized viral DNAs need to be retransported to the nucleus of the infected hepatocyte. 7 Therefore, the replicative forms of viral DNA are a...

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Formation of the pool of covalently closed circular viral DNA in hepadnavirus-infected cells

Cited by 609 publications

References 29 publications

Quantitative hepatitis B surface antigen and hepatitis B e antigen titers in prediction of treatment response to entecavir

Quantitative hepatitis B surface antigen and hepatitis B e antigen titers in prediction of treatment response to entecavir

The Pre-S region determines the intracellular localization and appearance of hepatitis B virus

Increased hepatocyte turnover and inhibition of woodchuck hepatitis B virus replication by adefovirIn vitro do not lead to reduction of the closed circular DNA

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