Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0019163 (hepatitis B)
 38,309 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Structural and nonstructural regions of the HCV-encoded polyprotein have been expressed in recombinant yeast, bacteria, or insect cells and used to capture and measure reactive antibodies circulating in different individuals. The putative nucleocapsid protein (C) and nonstructural proteins 3-5 (NS3-NS5) were found to contain the most immunodominant epitopes. The NS3, NS4, and C regions were expressed in yeast in the form of a fused, chimeric polyprotein (C25) and a capture assay for reactive antibody was developed. This anti-C25 assay detects all previously identified HCV-seropositive cases and provides a substantially more sensitive diagnostic for both acute and chronic HCV infections than the current anti-C100-3 (NS4) assay. Anti-C25 was detected more frequently than anti-C100-3 in chronic, transfusion-associated non-A, non-B hepatitis patients from the United States (95% vs. 71%) and Japan (98% vs. 82%), in cryptogenic cirrhosis patients from the United States (62% vs. 28%), and in hepatitis B surface antigen-negative cases of hepatocellular carcinoma from Japan (83% vs. 63%). These data indicate that HCV has a greater role in these liver diseases than was previously thought. In volunteer United States blood donors sampled following the introduction of anti-C100-3 screening, the prevalence of anti-C25 and anti-C100-3 was 0.5% and 0.08%, respectively.
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PMID:Diagnosis of hepatitis C virus (HCV) infection using an immunodominant chimeric polyprotein to capture circulating antibodies: reevaluation of the role of HCV in liver disease. 127 66

We have previously described a mutant hepatitis B virus (HBV) with a fused X-C open reading frame (ORF) resulting from a single nucleotide insertion in the X-C overlapping region. A stably transformed cell line producing HBV particles, HepG2-K8, was established by transfecting the human hepatoma cell line HepG2 with a plasmid carrying four tandem repeats of the mutant HBV genome. The virus particles secreted into the culture medium were characterized by density gradient centrifugation and electron microscopy. The particles, similar to Dane particles by morphology and density, contained the mature HBV genome and endogenous DNA polymerase activity. Six HBV-specific transcripts of 4.0, 3.5, 2.2, 2.1, 1.2 and 0.9 kb were detected in HepG2-K8 cells by Northern blot analysis. cDNA cloning and sequence analysis of X mRNA showed that an elongated X ORF encoding 193 amino acids was created by a frameshift mutation in the 3'-terminal region of the wild-type X ORF and that the formation of an in-frame termination codon (TAA) resulted from polyadenylation. This elongated X gene product exerted transcriptional trans-activation.
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PMID:Replication of a mutant hepatitis B virus with a fused X-C reading frame in hepatoma cells. 132 98

Hepatitis B core protein (HBcAg) is a potent antigen that gives both a T-cell-dependent and a T-cell-independent antibody response. It has been shown that a foreign epitope can be fused to the amino terminus of HBcAg without affecting particle integrity, and that the resulting chimaeric cores retain the immunogenicity of the foreign epitope. Here we describe the efficient expression in yeast of two different chimaeric cores, carrying epitopes of Foot and Mouth Disease Virus (FMDV) or human chorionic gonadotrophin (hCG), which are candidates for FMD and contraceptive vaccines, respectively. These cores could not be produced in E. coli in soluble form but were expressed to high levels in yeast. We constructed a yeast expression vector that allows rapid production of different chimaeric cores by cloning in cassettes encoding foreign epitopes. Both FMDV and hCG-cores were shown to present the epitopes at the surface of the particles. The FMDV-cores produced in yeast were efficient inducers of neutralising antibodies in guinea-pigs after one low dose.
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PMID:Expression in yeast of amino-terminal peptide fusions to hepatitis B core antigen and their immunological properties. 136 94

The nucleocapsid (HBcAg) of the hepatitis B virus (HBV) has been suggested as a carrier moiety for vaccine purposes. We investigated the influence of the position of the inserted epitope within hybrid HBcAg particles on antigenicity and immunogenicity. For this purpose, genes coding for neutralizing epitopes of the pre-S region of the HBV envelope proteins were inserted at the amino terminus, the amino terminus through a precore linker sequence, the truncated carboxy terminus, or an internal site of HBcAg by genetic engineering and were expressed in Escherichia coli. All purified hybrid HBc/pre-S polyproteins were particulate. Amino- and carboxy-terminal-modified hybrid HBc particles retained HBcAg antigenicity and immunogenicity. In contrast, insertion of a pre-S(1) sequence between HBcAg residues 75 and 83 abrogated recognition of HBcAg by 5 of 6 anti-HBc monoclonal antibodies and diminished recognition by human polyclonal anti-HBc. Predictably, HBcAg-specific immunogenicity was also reduced. With respect to the inserted epitopes, a pre-S(1) epitope linked to the amino terminus of HBcAg was not surface accessible and not immunogenic. A pre-S(1) epitope fused to the amino terminus through a precore linker sequence was surface accessible and highly immunogenic. A carboxy-terminal-fused pre-S(2) sequence was also surface accessible but weakly immunogenic. Insertion of a pre-S(1) epitope at the internal site resulted in the most efficient anti-pre-S(1) antibody response. Furthermore, immunization with hybrid HBc/pre-S particles exclusively primed T-helper cells specific for HBcAg and not the inserted epitope. These results indicate that the position of the inserted B-cell epitope within HBcAg is critical to its immunogenicity.
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PMID:The position of heterologous epitopes inserted in hepatitis B virus core particles determines their immunogenicity. 137 83

The hepatitis B virus envelope gene encodes three transmembrane proteins in frame; S, the product of S gene; M, the product of M (pre-S2 + S) gene; and L, the product of L (pre-S1 + pre-S2 + S) gene. Unlike the S and M proteins, attempts to efficiently synthesize L proteins and assemble them into L protein particles in various eukaryotic cells have been unsuccessful, probably because of the presence of the pre-S1 peptide with an unknown function which appears to be inhibitory to the host secretory apparatus. To investigate the role of the pre-S1 peptide, we constructed an L gene fused with a synthetic gene for chicken-lysozyme signal peptide (C-SIG) at the 5'-terminal and placed the resultant gene under the control of the yeast glyceraldehyde-3-phosphate dehydrogenase gene promoter. After the fused-C-SIG peptide was correctly processed by the yeast secretory apparatus, a yeast transformant synthesized a protein with a molecular mass of approximately 52 kDa at a level of 42% of the total soluble protein. Electron micrographic observation showed that the gene products assembled into 23-nm spherical and filamentous particles. The pre-S peptide of the gene product was deposited into the endoplasmic reticulum (ER) lumen and well-glycosylated. It seemed that the gene products were accumulated as particles in certain specific membrane structures of the yeast secretory apparatus. Moreover, both the amount of mRNAs specific for the L gene and the in vivo stability of the synthesized L proteins did not change significantly by the addition of the C-SIG gene. These findings indicated that, if the pre-S1 peptide penetrates the ER membrane efficiently, the L proteins can be synthesized cotranslationally, translocate across the ER membrane with its S region, and then assemble by themselves into the particle form. Therefore, the pre-S1 peptide may involve weak or reduced signal peptide activity for recognition by the secretory apparatus and/or for the transport of the pre-S peptide into the ER lumen.
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PMID:Hepatitis B virus envelope L protein particles. Synthesis and assembly in Saccharomyces cerevisiae, purification and characterization. 137 Apr 86

Peripheral blood mononuclear cells (PBMC) from 13 healthy hepatitis B vaccines were transformed with the Epstein-Barr virus (EBV) and lymphoblastoid cell lines (LCL) producing antibodies to hepatitis B surface antigen (anti-HBs antibodies). Seven LCL and two clones secreting human anti-HBs monoclonal antibody were generated and their antibodies purified. One clone was fused with a mouse myeloma and the antibody from a cloned anti-HBs secreting heterohybridoma purified. One of the 10 purified human anti-HBs antibodies was characterized as IgG4, the remainder were IgG1. The antibodies had either kappa or lambda light chains. Five of the antibodies which were conjugated to horseradish peroxidase recognised the "a" group determinants.
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PMID:Development and characterization of human anti-HBs antibodies. 137 11

A Gag protein segment of human immunodeficiency virus 1 (HIV-1) has been fused to a C terminally truncated core antigen of hepatitis B virus (HBcAg) using an E. coli expression system. Fusion of 90 amino acids of HIV-1 Gag protein to HBcAg still allowed the formation of capsids presenting on their surface epitopes of HIV-1 core protein, whereas fusion of 317, 189, or 100 amino acids of Gag prevented self-assembly of chimeric particles. Mice immunized with recombinant particles emulsified with Freund's complete adjuvant (CFA) or aluminium hydroxide developed high anti-HBcAg titers. However, anti-HIVp24 antibodies were detected only in mice inoculated with immunogen emulsified with CFA.
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PMID:Immunogenicity of recombinant core particles of hepatitis B virus containing epitopes of human immunodeficiency virus 1 core antigen. 138 12

A hepatitis B virus preS2 deletion library with the preS2 sequence fused to the coat protein of the RNA phage fr (fr CP) as a carrier has been constructed and used for the approximate localization of epitope recognized by a panel of murine monoclonal anti-preS2 antibodies. DNA copies of putative preS2 epitopes were synthesized and cloned within the fr CP gene. Tetrapeptide Gln-Asp-Pro-Arg (QDPR) corresponding to the preS (132-135) sequence was found to be the minimal sufficient recognition site for one of the monoclonal antibodies, S26. The closely related tetrapeptide EDPR did not mimic the epitope activity of QDPR.
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PMID:Tetrapeptide QDPR is a minimal immunodominant epitope within the preS2 domain of hepatitis B virus. 144 23

We have constructed a recombinant baculovirus from Autographa californica nuclear polyhedrosis virus, called AcX, that expresses the gene encoding the hepatitis B virus X protein in infected Spodoptera frugiperda (Sf21AE) insect cells. A 16.5-kDa monomer and a 33-kDa dimer of the X protein were detected in extracts from AcX-infected cells on immunoblots using a polyclonal anti-X antibody. The biological activity of the insect cell-produced X protein was assayed by fusing AcX-infected Sf21AE cells with African green monkey kidney (CV-1) cells and then transfecting the fused cells with the reporter plasmid pSV2cat. The expression of the cat gene in CV-1:Sf21AE(AcX) fusions was seven times higher than that derived from CV-1:Sf21AE(AcMNPV) fusions, indicating that the insect cell-produced X protein was functional. The transactivation function of the insect cell-produced X protein was also verified by scrape-loading nuclear extracts of AcX-infected Sf21AE cells into pSV2cat-transfected CV-1 cells. Treatment of the AcX-infected cell nuclear extracts with anti-X antisera prior to scrape-loading eliminated the transactivating activity of the extracts. We conclude that the insect cell-produced X protein was functionally identical to that generated in mammalian cells.
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PMID:A functional hepatitis B virus X protein produced in insect cells. 166 Feb 11

We studied the effects of transfection of the normal c-Ha-ras gene, rasGly-12, and its oncogenic mutant, rasVal-12, on expression of the alpha-fetoprotein (AFP) and albumin genes in a human hepatoma cell line, HuH-7. The mutant and, to a lesser extent, the normal ras gene caused reduction of the AFP mRNA but not the albumin mRNA level in transfected HuH-7 cells. Cotransfection experiments with a rasVal-12 expression plasmid and a chloramphenicol acetyltransferase reporter gene fused to AFP regulatory sequences showed that rasVal-12 suppressed the activity of enhancer and promoter regions containing A + T-rich sequences (AT motif). In contrast, rasVal-12 did not affect the promoter activity of the albumin and human hepatitis B virus pre-S1 genes even though these promoters contain homologous A + T-rich elements. ras transfection appeared to induce phosphorylation of nuclear proteins that interact with the AFP AT motif, since gel mobility analysis revealed the formation of slow-moving complexes which was reversed by phosphatase treatment. However, similar changes in complex formation were observed with the albumin and hepatitis B surface antigen pre-S1 promoters. Therefore, this effect alone cannot explain the specific down regulation of the AFP promoter and enhancer activity. ras-mediated suppression of the AFP gene may reflect the process of developmental gene regulation in which AFP gene transcription is controlled by a G-protein-linked signal transduction cascade triggered by external growth stimuli.
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PMID:c-Ha-ras down regulates the alpha-fetoprotein gene but not the albumin gene in human hepatoma cells. 169 Aug 41


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