scholarly journals Nucleolar Localization of Human Hepatitis B Virus Capsid Protein

2004 ◽  
Vol 78 (24) ◽  
pp. 13653-13668 ◽  
Author(s):  
Bo Ning ◽  
Chiaho Shih
Keyword(s):  
Amino Acid ◽  
Hepatitis B Virus ◽  
Hepatitis B ◽  
Cell Epitope ◽  
Core Antigen ◽  
Wild Type ◽  
Confocal Immunofluorescence Microscopy ◽  
Human Hepatitis ◽  
C Terminus ◽  
B Virus

ABSTRACT Wild-type human hepatitis B virus (HBV) exhibits selective export of virions containing mature genomes. In contrast, changing an isoleucine to a leucine at amino acid 97 (I97L) of the HBV core antigen (HBcAg) causes it to release immature genomes. To elucidate the structure-function relationship of HBcAg at amino acid 97, we systematically replaced the isoleucine residue at this position with 18 other amino acids via mutagenesis. Twelve of the 18 mutants exhibited no significant phenotype, while five new mutants displayed strong phenotypes. The I97D mutant had a near lethal phenotype, the I97P mutant exhibited a significantly reduced level of virion secretion, and the I97G mutant lacked the full-length relaxed circular form of viral DNA. The tip of the spike of the capsid particle is known to contain a predominant B-cell epitope. However, the recognition of this exposed epitope by an anti-HBc antibody appeared to be affected by the I97E mutation or by histidine tagging at the C terminus of mutant HBcAg, which is presumably in the capsid interior. Surprisingly, the nuclear HBcAg of mutants I97E and I97W, produced from either a replicon or an expression vector, was found to be colocalized with nucleolin and B23 at a frequency of nearly 100% by confocal immunofluorescence microscopy. In contrast, this colocalization occurred with wild-type HBcAg only to a limited extent. We also noted that nucleolin-colocalizing cells were often binucleated or apoptotic, suggesting that the presence of HBcAg in the nucleolus may perturb cytokinesis. The mechanism of this phenomenon and its potential involvement in liver pathogenesis are discussed. To our knowledge, this is the first report of nucleolar HBcAg in culture.

scholarly journals Subtype-Independent Immature Secretion and Subtype-Dependent Replication Deficiency of a Highly Frequent, Naturally Occurring Mutation of Human Hepatitis B Virus Core Antigen

1999 ◽  
Vol 73 (12) ◽  
pp. 10122-10128 ◽  
Author(s):  
Thomas Ta-Tung Yuan ◽  
Pei-Ching Tai ◽  
Chiaho Shih
Keyword(s):  
Amino Acid ◽  
Hepatitis B Virus ◽  
Hepatitis B ◽  
Core Protein ◽  
Hbv Dna ◽  
Core Antigen ◽  
Wild Type ◽  
Virion Assembly ◽  
Human Hepatitis ◽  
B Virus

ABSTRACT The most frequent mutation of the human hepatitis B virus (HBV) core antigen occurs at amino acid 97. Recently, a phenylalanine (F)-to-leucine (L) mutation at this position (mutant F97L) in HBV surface antigen subtype ayw has been shown to result in an immature secretion phenotype, which is characterized by the nonselective export of an excessive amount of virions containing minus-strand, single-stranded HBV DNA. While subtype aywmutant F97L has been found in Europe, the major reservoir of HBV resides in Asia and Africa. We report here that the immature secretion phenotype indeed can be found in an HBV strain (subtypeadr) prevalent in Asia, changing from an isoleucine (I) to a leucine (mutant I97L). Despite its immature secretion phenotype, theadr variant I97L replicates as well as its parentaladr wild-type I97I, supporting the conclusion that the extracellular phenotype of immature secretion is not a consequence of the intracellular HBV DNA replication defect. Further studies demonstrated that it is the acquisition of a leucine, rather than the loss of a wild-type amino acid at codon 97, that is important for immature secretion. We conclude that immature secretion is a subtype-independent phenotype and deficiency in intracellular DNA synthesis is a subtype-dependent phenotype. The former is caused by thetrans-acting effect of a mutant core protein, while the latter by a cis-acting effect of a mutated nucleotide on the ayw genome. These immature secretion variants provide an important tool for studying the regulation of HBV virion assembly and secretion.

scholarly journals Exposure of RNA Templates and Encapsidation of Spliced Viral RNA Are Influenced by the Arginine-Rich Domain of Human Hepatitis B Virus Core Antigen (HBcAg 165-173)

2005 ◽  
Vol 79 (3) ◽  
pp. 1871-1887 ◽  
Author(s):  
Sophie Le Pogam ◽  
Pong Kian Chua ◽  
Margaret Newman ◽  
Chiaho Shih
Keyword(s):  
Hepatitis B Virus ◽  
Hepatitis B ◽  
Full Length ◽  
Core Antigen ◽  
Wild Type ◽  
Positive Strand ◽  
Rich Domain ◽  
Human Hepatitis ◽  
C Terminus ◽  
B Virus

ABSTRACT Previously, human hepatitis B virus (HBV) mutant 164, which has a truncation at the C terminus of the HBV core antigen (HBcAg), was speculated to secrete immature genomes. For this study, we further characterized mutant 164 by different approaches. In addition to the 3.5-kb pregenomic RNA (pgRNA), the mutant preferentially encapsidated the 2.2-kb or shorter species of spliced RNA, which can be reverse transcribed into double-stranded DNA before virion secretion. We observed that mutant 164 produced less 2.2-kb spliced RNA than the wild type. Furthermore, it appeared to produce at least two different populations of capsids: one encapsidated a nuclease-sensitive 3.5-kb pgRNA while the other encapsidated a nuclease-resistant 2.2-kb spliced RNA. In contrast, the wild-type core-associated RNA appeared to be resistant to nuclease. When arginines and serines were systematically restored at the truncated C terminus, the core-associated DNA and nuclease-resistant RNA gradually increased in both size and signal intensity. Full protection of encapsidated pgRNA from nuclease was observed for HBcAg 1-171. A full-length positive-strand DNA phenotype requires positive charges at amino acids 172 and 173. Phosphorylation at serine 170 is required for optimal RNA encapsidation and a full-length positive-strand DNA phenotype. RNAs encapsidated in Escherichia coli by capsids of HBcAg 154, 164, and 167, but not HBcAg 183, exhibited nuclease sensitivity; however, capsid instability after nuclease treatment was observed only for HBcAg 164 and 167. A new hypothesis is proposed here to highlight the importance of a balanced charge density for capsid stability and intracapsid anchoring of RNA templates.

scholarly journals The Mechanism of an Immature Secretion Phenotype of a Highly Frequent Naturally Occurring Missense Mutation at Codon 97 of Human Hepatitis B Virus Core Antigen

1999 ◽  
Vol 73 (7) ◽  
pp. 5731-5740 ◽  
Author(s):  
Thomas Ta-Tung Yuan ◽  
Gautam Kumar Sahu ◽  
William E. Whitehead ◽  
Richard Greenberg ◽  
Chiaho Shih
Keyword(s):  
Hepatitis B Virus ◽  
Hepatitis B ◽  
Missense Mutation ◽  
Core Protein ◽  
Core Antigen ◽  
Minus Strand ◽  
Wild Type ◽  
Human Hepatitis ◽  
B Virus ◽  
Core Particles

ABSTRACT A very frequent missense mutation at codon 97 of human hepatitis B virus (HBV) core antigen (HBcAg) has been found in chronic carriers worldwide. Functional characterization of this mutant revealed one intracellular and two extracellular phenotypes in contrast to wild-type HBV: (i) a 6- to 12-fold decrease in the level of the full-length relaxed circular DNA, a 4- to 5-fold decrease in the plus-strand DNA, and an approximately 1.8-fold decrease in the minus-strand and overall DNA levels in the intracellular viral core particles; (ii) a 5.7-fold increase in the immature secretion of Dane particles, containing minus-strand, single-stranded virion DNA; and (iii) a significant reduction of nonenveloped core particles in the medium. The steady-state levels of mutant and wild-type core proteins expressed from the same vector appeared to be similar. Using a complementation assay and gradient centrifugation analysis, we demonstrated that this mutant core protein alone is necessary and sufficient for immature secretion. The decreased level of intracellular HBV DNA is caused by both the cis defect of the mutant genome and thetrans defect of the mutant core protein. We have dissected further the relationship between the intracellular and extracellular phenotypes of mutant F97L. The pleiotropic effects of the HBcAg codon 97 mutation were observed consistently in several different experimental settings. The mechanism and biological significance of these findings are discussed.

Transcription of human hepatitis B virus core antigen gene sequences in an in vitro HeLa cellular extract

Virology ◽  
1981 ◽  
Vol 111 (2) ◽  
pp. 647-652 ◽  
Author(s):  
Prasanta R. Chakraborty ◽  
Nelson Ruiz-Opazo ◽  
David A. Shafritz
Keyword(s):  
Hepatitis B Virus ◽  
Hepatitis B ◽  
Core Antigen ◽  
Gene Sequences ◽  
Antigen Gene ◽  
Virus Core ◽  
Human Hepatitis ◽  
B Virus ◽  
Cellular Extract

scholarly journals Naturally Occurring Hepatitis B Virus B-Cell and T-Cell Epitope Mutants in Hepatitis B Vaccinated Children

2013 ◽  
Vol 2013 ◽  
pp. 1-7 ◽  
Author(s):  
Yu-Min Lin ◽  
Guey-Mei Jow ◽  
Shu-Chi Mu ◽  
Bing-Fang Chen
Keyword(s):  
Hepatitis B Virus ◽  
T Cell ◽  
Hepatitis B ◽  
B Cell ◽  
Cell Epitope ◽  
Hbv Infection ◽  
Core Antigen ◽  
T Cell Epitope ◽  
Naturally Occurring ◽  
B Virus

To control hepatitis B virus (HBV) infection, a universal HBV vaccination program for infants was launched in Taiwan in 1984. The aim of this study was to investigate the role of B-cell and T-cell epitope variations of HBsAg and polymerase in HBV infection in vaccinated children. One hundred sixty-three sera from vaccinated children were enrolled randomly. HBV serum markers, including hepatitis B surface antigen (HBsAg) and antibodies to HBsAg (anti-HBs) and core antigen (anti-HBc), were detected by ELISA. Nucleotide sequences encoding the S and the pre-S regions of HBsAg were analyzed in all HBsAg positive sera. Five children were HBsAg positive. Sequence analysis of S, pre-S, and overlapped polymerase (P) genes showed that HBV isolates of HBsAg-positive vaccinees were variants; no G145R but G145A and other substitutions were found in the “a” determinant. Fifteen, six, and eight amino acid substitutions within B-cell and T-cell epitopes of S, pre-S, and P regions were detected, respectively. Several immune-epitope mutants, such as S45T/A, N131T, I194V, and S207N in S, were detected in all isolates. In conclusion, our results suggested that these naturally occurring immunoepitope mutants, which changed their immunogenicity leading to escape from immune response, might cause HBV infection.

scholarly journals Persistence of Hepatitis B Virus DNA and the Tempos between Virion Secretion and Genome Maturation in a Mouse Model

2019 ◽  
Vol 93 (22) ◽  
Author(s):  
Szu-Yao Wu ◽  
Ya-Shu Chang ◽  
Tien-Hua Chu ◽  
Chiaho Shih
Keyword(s):  
Amino Acid ◽  
Hepatitis B Virus ◽  
Hepatitis B ◽  
Mouse Model ◽  
Core Protein ◽  
Wild Type ◽  
Viral Dna ◽  
Naturally Occurring ◽  
B Virus

ABSTRACT Hepatitis B virus (HBV) core protein (HBc) accumulates frequent mutations in natural infection. Wild-type HBV is known to secrete predominantly virions containing mature DNA genome. However, a frequent naturally occurring HBc variant, I97L, changing from an isoleucine to a leucine at amino acid 97, exhibited an immature secretion phenotype in culture, which preferentially secretes virions containing immature genomes. In contrast, mutant P130T, changing from a proline to a threonine at amino acid 130, exhibited a hypermaturation phenotype by accumulating an excessive amount of intracellular fully mature DNA genome. Using a hydrodynamic delivery mouse model, we studied the in vivo behaviors of these two mutants, I97L and P130T. We detected no naked core particles in all hydrodynamically injected mice. Mutant I97L in mice exhibited pleiotropic phenotypes: (i) excessive numbers of serum HBV virions containing immature genomes, (ii) significantly reduced numbers of intracellular relaxed-circle and single-stranded DNAs, and (iii) less persistent intrahepatic and secreted HBV DNAs than wild-type HBV. These pleiotropic phenotypes were observed in both immunocompetent and immunodeficient mice. Although mutant P130T also displayed a hypermaturation phenotype in vivo, it cannot efficiently rescue the immature virion secretion of mutant I97L. Unexpectedly, the single mutant P130T exhibited in vivo a novel phenotype in prolonging the persistence of HBV genome in hepatocytes. Taken together, our studies provide a plausible rationale for HBV to regulate envelopment morphogenesis and virion secretion via genome maturity, which is likely to play an important role in the persistence of viral DNA in this mouse model. IMPORTANCE Chronic infection with human hepatitis B virus (HBV) could lead to cirrhosis and hepatoma. At present, there is no effective treatment to eradicate the virus from patients. HBV in chronic carriers does not exist as a single homogeneous population. The most frequent naturally occurring mutation in HBV core protein occurs at amino acid 97, changing an isoleucine to leucine (I97L). One dogma in the field is that only virions containing a mature genome are preferentially secreted into the medium. Here, we demonstrated that mutant I97L can secrete immature genome in mice. Although viral DNA of mutant I97L with immature genome is less persistent than wild-type HBV in time course experiments, viral DNA of mutant P130T with genome hypermaturation, surprisingly, is more persistent. Therefore, virion secretion regulated by genome maturity could influence viral persistence. It remains an open issue whether virion secretion could be a drug target for HBV therapy.

scholarly journals A Mechanism To Explain the Selection of the Hepatitis e Antigen-Negative Mutant during Chronic Hepatitis B Virus Infection

2008 ◽  
Vol 83 (3) ◽  
pp. 1379-1392 ◽  
Author(s):  
Lars Frelin ◽  
Therese Wahlström ◽  
Amy E. Tucker ◽  
Joyce Jones ◽  
Janice Hughes ◽  
...  
Keyword(s):  
Hepatitis B Virus ◽  
Liver Injury ◽  
Hepatitis B ◽  
Immune Responses ◽  
Hepatitis E ◽  
Core Antigen ◽  
Wild Type ◽  
Chronic Hepatitis B Virus ◽  
B Virus ◽  
Selection Of

ABSTRACT Hepatitis B virus (HBV) expresses two structural forms of the nucleoprotein, the intracellular nucleocapsid (hepatitis core antigen [HBcAg]) and the secreted nonparticulate form (hepatitis e antigen [HBeAg]). The aim of this study was to evaluate the ability of HBcAg- and HBeAg-specific genetic immunogens to induce HBc/HBeAg-specific CD4+/CD8+ T-cell immune responses and the potential to induce liver injury in HBV-transgenic (Tg) mice. Both the HBcAg- and HBeAg-specific plasmids primed comparable immune responses. Both CD4+ and CD8+ T cells were important for priming/effector functions of HBc/HBeAg-specific cytotoxic T-lymphocyte (CTL) responses. However, a unique two-step immunization protocol was necessary to elicit maximal CTL priming. Genetic vaccination did not prime CTLs in HBe- or HBc/HBeAg-dbl-Tg mice but elicited a weak CTL response in HBcAg-Tg mice. When HBc/HBeAg-specific CTLs were adoptively transferred into HBc-, HBe-, and HBc/HBeAg-dbl-Tg mice, the durations of the liver injury and inflammation were significantly greater in HBeAg-Tg recipient mice than in HBcAg-Tg mice. Importantly, liver injury in HBc/HBeAg-dbl-Tg mice was similar to the injury observed in HBeAg-Tg mice. Loss of HBeAg synthesis commonly occurs during chronic HBV infection; however, the mechanism of selection of HBeAg-negative variants is unknown. The finding that hepatocytes expressing wild-type HBV (containing both HBcAg and HBeAg) are more susceptible to CTL-mediated clearance than hepatocytes expressing only HBcAg suggest that the HBeAg-negative variant may have a selective advantage over wild-type HBV within the livers of patients with chronic infection during an immune response and may represent a CTL escape mutant.

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