The hepatitis B virus (HBV) precore protein inhibits HBV replication in transgenic mice

Guidotti, Luca G.; Matzke, Brent; Pasquinelli, Claudio; Shoenberger, Jan M.; Rogler, Charles E.; Chisari, Francis V.

doi:10.1128/jvi.70.10.7056-7061.1996

Cited by 114 publications

(40 citation statements)

References 40 publications

(59 reference statements)

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“…45,46 In transgenic mice, overexpression of the PC protein eliminated nucleocapsid particles from the cytoplasm of the hepatocytes and abolished HBV replication without affecting the hepatic steady-state content of pregenomic RNA. 48 In our study, we found no evidence in support of a role for the precore protein in inhibiting viral DNA production for either WT or lamivudine-resistant HBV during 7 days in culture.…”

Section: Discussioncontrasting

confidence: 82%

“…1,43,44 Previous in vitro studies suggested that the G1896A mutation may be selected because of its ability to enhance HBV replication, 45,46 because the PC protein can mediate inhibition of HBV DNA synthesis. 47,48 Point mutations, which abolish proper expression of the PC gene, enhance the yield of progeny viral DNA. 45 Nonsecreted HBeAg precursor protein (p22), rather than secreted HBeAg, has been shown to be responsible for the inhibition of viral DNA synthesis and appeared to act by forming hybrid nucleocapsid structures with p21, the capsid protein.…”

Section: Discussionmentioning

confidence: 99%

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Effect of the G1896A precore mutation on drug sensitivity and replication yield of lamivudine-resistant HBV in vitro

et al. 2003

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Hepatitis B e antigen (HBeAg) negative chronic hepatitis B (CHB) is frequently caused by a mutation (G1896A) in the hepatitis B virus (HBV) precore (PC) reading frame that creates a stop codon, causing premature termination of the PC protein. During lamivudine treatment, drug resistance develops at a similar rate in HBeAg positive and HBeAg negative CHB. Lamivudine-resistant HBV mutants have been shown to replicate inefficiently in vitro in the absence of PC mutations, but it is unknown whether the presence of PC mutations affects replication efficiency or antiviral sensitivity. This study utilized the recombinant HBV baculovirus system to address these issues. HBV baculoviruses encoding the G1896A PC stop codon mutation were generated in wild-type (WT) and lamivudine-resistant (rtM204I and rtL180M ؉ rtM204V) backgrounds, resulting in a panel of 6 related recombinant baculoviruses. In vitro assays were performed to compare the sensitivities of the PC mutant viruses with lamivudine and adefovir and to compare relative replication yields. The PC mutation did not significantly affect sensitivities to either adefovir or lamivudine. WT HBV and PC mutant HBV showed similar replication yields, whereas the replication yields of the lamivudine-resistant mutants were greatly reduced in HBeAg positive HBVs, confirming previous observations. However, the presence of the PC mutation was found to compensate for the replication deficiency in each of the lamivudine-resistant mutants, increasing the replication yields of each virus. In conclusion, the PC stop codon mutation appears to increase the replication efficacy of lamivudine-resistant virus but does not affect in vitro drug sensitivity. (HEPATOLOGY 2003;37:27-35.) H epatitis B e antigen (HBeAg) negative chronic hepatitis B (CHB), a phase in the natural history of CHB, is marked by the selection of hepatitis B viruses (HBV) unable to secrete HBeAg and has become the major form of disease presentation in many parts of the world. 1 The most common of several mutations that can cause HBeAg negativity is a guanine to adenine transition at nucleotide position 1,896 (G1896A), which creates a TAG stop codon at codon 28 of the precore (PC) protein. [1][2][3][4][5] Interferon alfa and lamivudine are the only therapeutic agents approved for treatment of CHB. 6 Lamivudine is regarded as safe and as efficacious as interferon alfa, but the percentage of patients with HBeAg positive CHB who undergo HBeAg seroconversion increases with the duration of treatment. 7 Seroconversion rates between 11% and 15% per year have been reported over treatment periods up to 3 years. [7][8][9][10] Unfortunately, the frequency of antiviral drug resistance increases with the duration of therapy, rising to as high as 66% after 3 years. 10,11 The most common mutations conferring lamivudine resistance affect the active site YMDD (tyrosine-methionine-aspartate-aspartate) motif in the C domain of the HBV polymerase protein, causing the methionine (M) residue (amino acid 204) to be replaced with either isole...

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Section: Discussioncontrasting

confidence: 82%

Section: Discussionmentioning

confidence: 99%

Effect of the G1896A precore mutation on drug sensitivity and replication yield of lamivudine-resistant HBV in vitro

et al. 2003

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“…Our data also supported previous epidemiological conclusions that the precore G1896A mutant is negatively correlated with occurrence of HCC. (2,4) HBeAg is a nonstructural protein of HBV, although the majority of HBeAg is secreted, 20%-30% of the mature protein is retained in the cytoplasm, (25)(26)(27) which was confirmed by our observation that HBeAg could be readily detected in cytoplasm ( Fig. 1D).…”

Section: Discussionsupporting

confidence: 72%

Hepatitis B e antigen and its precursors promote the progress of hepatocellular carcinoma by interacting with NUMB and decreasing p53 activity

et al. 2016

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Hepatitis B viral infection is one of the leading causes of hepatocellular carcinoma (HCC) worldwide. Although several viral factors have been identified that may increase the risk for HCC development, the molecular mechanisms leading to the transformation of normal hepatocytes into cancer cells remain elusive. In this study, we demonstrated that the intracellular hepatitis B e antigen (HBeAg) and its precore precursors, but not their homologous core protein, could associate with NUMB and thereby impair the stability and transcriptional activity of tumor suppressor p53. HBeAg and its precursors could disrupt p53-NUMB and HDM2-NUMB interactions and tricomplex p53-HDM2-NUMB formation, inhibit the acetylation and translocation of p53 from cytosol to the nucleus, promote HDM2-mediated ubiquitination and degradation of p53, and suppress p53-dependent apoptosis. A xenograft tumorigenicity assay showed that expression of HBeAg and its precursors promoted carcinogenesis in a mouse model. Immunohistochemical analysis of the bioptic liver samples of HCC patients revealed that HBeAg positivity was associated with reduced transcriptional activity of p53. Taken together, the results suggest a role of intracellular HBeAg and its precursors in HCC development. Conclusion: HBeAg and its precursors promote HDM2-mediated degradation and impair transcriptional activity of p53 by interacting with NUMB, consequently contributing to HCC development. (HEPATOLOGY 2016;64:390-404) H epatitis B viral (HBV) infection represents a major public health problem, with more than 350 million humans chronically infected worldwide at risk of developing chronic liver diseases and hepatocellular carcinoma (HCC).(1) HBV is a small, enveloped DNA virus with four open reading frames (C, P, S, and X) in the genome, which results in expression of the seven different HBV proteins through use of varying in-frame start codons. For example, open reading frame preC-C encodes both hepatitis B core antigen (HBcAg) and the precore protein (p25), the latter being processed in the endoplasmic reticulum to produce hepatitis B e antigen (HBeAg or p17) and its intermediate (p22).It has been proposed that HBeAg may contribute to the development of liver cancer, and its role as a marker of active viral replication is most likely associated with increased risk of HCC.(2) Mutations in the precore region, which were the first major common variants of HBV discovered, (3) are first detectable around the time of HBeAg seroconversion and include mutations that prevent HBeAg synthesis without interfering with the production of infectious virions. The most common of these mutations is a G to A substitution at nucleotide 1896Abbreviations: EGFP, enhanced green fluorescent protein; HA, hemagglutinin; HBcAg, hepatitis B core antigen; HBV, hepatitis B virus; HBeAg, hepatitis B e antigen; HCC, hepatocellular carcinoma; mRNA, messenger RNA; wt, wild type.

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“…A reduced HBeAg production may enhance viral replication. 26,27 In this study, mutants were not detectable by a solution hybridization assay except for 2 patients who developed DNA breakthrough. It was reported that interferon therapy was frequently associated with the simultaneous decrease in titer of viral DNA and the emergence of precore mutant in chronic type B hepatitis.…”

Section: Discussionmentioning

confidence: 57%

Reversion From Precore/Core Promoter Mutants to Wild–Type Hepatitis B Virus During the Course of Lamivudine Therapy

2000

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The effect of lamivudine administration on the evolution of precore/core promoter mutation is unknown. The aim of this study was to determine the changes of precore/core promoter sequences in chronic type B hepatitis patients treated with lamivudine. Serial sera were obtained from 11 patients before, at the beginning of, and during therapy. Serum samples were polymerase chain reaction-amplified, and nucleotide sequences of hepatitis B virus (HBV) were analyzed. At baseline, precore and core promoter mutations were found in 6 and 4 of 11 patients, respectively. A precore stop codon mutant was replaced by a wild-type virus in all 6 patients infected with precore mutant at a median treatment of 12 months (vs. before therapy; P ‫؍‬ .011). Mutations in the core promoter appeared in only 1 of 10 patients (vs. before therapy; P ‫؍‬ .021). However, precore and core promoter mutations appeared in 5 and 7 of 10 patients at a median treatment of 21 months, respectively. Acute exacerbation occurred after lamivudine withdrawal in 2 patients who had hepatitis B e antigen (HBeAg) loss or seroconversion. The serum remained HBeAg-negative throughout the study period, and each of 2 patients had precore wild-type virus during acute exacerbation. HBV mutants with core gene deletions are not eliminated completely during prolonged therapy in 2 patients in whom the HBV genomes had core gene deletions at baseline. In conclusion, lamivudine therapy resulted in reversion from precore/core promoter mutants to wild-type. However, mutations in the precore and core promoter region reappeared during prolonged therapy. HBeAg-negative wild-type precore hepatitis B virus could be selected after lamivudine withdrawal in patients who had HBeAg loss or seroconversion. (HEPATOLOGY 2000;32:1163-1169.)During the course of chronic hepatitis B virus (HBV) infection, natural seroconversion to antibody to hepatitis B e antigen (anti-HBe) usually correlates with cessation of high levels of viremia and clinical recovery. However, in areas with a high HBV prevalence, a significant number of anti-HBe-positive patients remain at high level viremia and eventually go on to develop severe and progressive disease. 1,2 Mutations in the precore region have been reported to be responsible for more than 95% of anti-HBe-positive chronic hepatitis in the Mediterranean area. 3,4 An inframe TAG stop codon developed in the distal precore region has been related to the absence of hepatitis B e antigen (HBeAg) secretion. 5,6 Lack of HBeAg expression could make the recognition of infected hepatocytes by killer lymphocytes less efficient, 7 and mutations in the precore region might enhance the stability of the secondary structure of the pregenome encapsidation signals, thus ensuring perpetuation of viral replication and therefore contributing to viral persistence. 8 Base exchanges in the second AT-rich region at position 1,762 and 1,764 of the core promoter have been reported in fulminant or chronic hepatitis as an isolated event or in association with the TAG stop codon in th...

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The hepatitis B virus (HBV) precore protein inhibits HBV replication in transgenic mice

Cited by 114 publications

References 40 publications

Effect of the G1896A precore mutation on drug sensitivity and replication yield of lamivudine-resistant HBV in vitro

Effect of the G1896A precore mutation on drug sensitivity and replication yield of lamivudine-resistant HBV in vitro

Hepatitis B e antigen and its precursors promote the progress of hepatocellular carcinoma by interacting with NUMB and decreasing p53 activity

Reversion From Precore/Core Promoter Mutants to Wild–Type Hepatitis B Virus During the Course of Lamivudine Therapy

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