Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0019158 (hepatitis)
 30,205 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

The recombinant hepatitis delta virus antigen was obtained as a chimaeric protein fused to the C-terminus of the phage MS2 RNA polymerase. Following induction of the temperature-sensitive promoter, two major polypeptides of about 34 kDa and 29 kDa, and two minor peptides about 21 kDa and 18 kDa, were obtained on PAGE. The 34-kDa protein was identified as the expected recombinant protein by confirming 82% of the primary structure using fast-atom-bombardment mass spectrometry. The most represented degradation product, i.e. the 29-kDa polypeptide, was also characterized by means of mass spectrometry and found to be produced by cleavage between amino acids 261 and 265. The presence of two main protein bands, with a similar difference in size, is also a typical feature of delta antigens, both extracted and recombinant, and it is considered to be derived either from heterogeneity of viral sequences, which can encode hepatitis delta antigen proteins of 195 and 214 amino acids, or from proteolysis of a single precursor. Since the data were obtained with a single viral sequence coding for 195 amino acids fused to 106 residues from MS2 polymerase, there is direct evidence that intrinsic structural properties of the protein sequence are able to cause a specific proteolysis resulting in the presence of two major forms, of which the smaller is 35-40 amino acids at the C-terminus. The recombinant protein can be used as an antigenic substitute of viral antigens both for immunoassays and for the preparation of anti-(hepatitis delta virus) antisera.
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PMID:Characterization by mass spectrometry of a recombinant hepatitis delta virus antigen and its proteolytic products. 154 Dec 67

The hepatitis delta antigen (HDAg) is a multifunctional protein. It forms the core-like structure of the hepatitis delta virus (HDV) but also enhances replication of HDV in the nucleus of the hepatocyte. A cDNA fragment encoding HDAg was inserted adjacent to the polyhedrin promoter of Autographa californica nuclear polyhedrosis virus present in the baculovirus transfer vector pVL941. After transfection of Spodoptera frugiperda (Sf9) cells a recombinant baculovirus Ac delta 1 was isolated and purified using filter hybridization techniques. Sf9 cells infected with Ac delta 1 express the HDAg as a non-fused, non-glycosylated protein with an abundance of up to 25% of the total cellular protein mass. Immunoblot analysis using a human polyclonal anti-HD conjugate identified a 22K and a 24K protein in the nucleus of Ac delta 1-infected Sf9 cells. Electron microscopic studies using immunogold labelling showed that the recombinant HDAg (recHDAg) was associated with the hetero-chromatin of the Sf9 cells. The recHDAg produced by Sf9 cells elicited anti-HD antibodies in chimpanzees when injected intramuscularly.
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PMID:Baculovirus-directed high level expression of the hepatitis delta antigen in Spodoptera frugiperda cells. 201 95

The proto-oncogene c-myc has been implicated in the formation of primary liver tumors in hepatitis virus-infected woodchucks. In one of these tumors, a DNA rearrangement placed the truncated c-myc gene downstream of a cellular sequence (hcr) in a head-to-tail configuration resulting in 50-fold enhanced levels of c-myc transcripts. Analysis of the tumor-specific c-myc RNA now demonstrates that transformed liver cells produce fused hcr/myc transcripts initiated from the hcr promoter and extending into c-myc coding sequences by differential splicing mechanisms. In phase fusion of the reading frames of both genes might result in the translation of the hcr/myc 2.0 kb RNA into a hybrid protein that would differ from the normal woodchuck c-myc gene product by 22 additional hcr amino acids at its amino-terminus. The production of inappropriate levels of modified or normal myc-encoded proteins is probably involved in the malignant process.
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PMID:Fused transcripts of c-myc and a new cellular locus, hcr in a primary liver tumor. 264 11

The E1-glycoprotein (Mr = 26,014; 228 amino acids) of mouse hepatitis virus A59 is a class III membrane glycoprotein which has been used in this study as a model system in the study of membrane integration and protein transport. The protein lacks an NH2-terminal cleavable signal sequence and spans the viral membrane three times. Hydrophobic domains I and III could serve as signal sequences for cotranslational membrane integration. Domain I alone was sufficient to translocate the hydrophilic NH2 terminus of E1 across the membranes as evidenced by glycosylation of a newly introduced N-glycosylation site. The COOH-terminal part of E1 involving amino acids Leu124 to Thr228 was found to associate tightly with membranes at the post-translational level, although this part of the molecule lacks pronounced hydrophobic sequences. Membrane protection assays with proteinase K showed that a 2-kDa hydrophilic fragment was removed from the COOH terminus of E1 indicating that the protein is largely embedded into the membrane. Microinjection of in vitro transcribed capped and polyadenylated mRNA into CV-1 cells or into secretory AtT20 pituitary tumor cells showed that the E1-protein accumulated in the Golgi but was not detectable at the plasma membrane or in secretory granules. The 28 NH2-terminal hydrophilic amino acid residues play no role in membrane assembly or in intracellular targeting. Various NH2-terminal portions of E1 were fused to Ile145 of the cytoplasmic N-protein of mouse hepatitis virus. The resulting hybrid proteins were shown to assemble into membranes in vitro and were detected either in the rough endoplasmic reticulum or transient vesicles of microinjected cells.
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PMID:Membrane integration and intracellular transport of the coronavirus glycoprotein E1, a class III membrane glycoprotein. 284 93

Liver biopsies from patients with alcoholic hepatitis, chemical hepatitis, or viral hepatitis types A, B, or non-A, non-B were examined by electron microscopy. Circular, fused, cytoplasmic membranes were observed in hepatocytes of 17% of patients with hepatitis type B and 92% of patients with hepatitis type non-A, non-B. The membrane alterations were not observed in hepatocytes of patients with the other types of hepatitis. The greater frequency of altered cytoplasmic membranes in hepatocytes of patients with non-A, non-B hepatitis was shown to be statistically significant (p less than 0.05) when compared to that in patients with viral hepatitis type B.
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PMID:Association of human hepatocellular membrane fusions with non-A, non-B hepatitis. 287 55

Monoclonal antibody-secreting cell lines were isolated after transformation of peripheral blood leukocytes with Epstein-Barr virus. Blood samples were obtained from human donors having circulating antibodies against hepatitis viruses (HAB, HBV), rubella, or rabies virus and from a chimpanzee infected with HAV. Dextran-isolated leukocytes were submitted to Epstein-Barr virus infection at low cell concentrations (1 X 10(4) cells X ml-1). Proliferating clones could be observed in 50-100% of the cultures within 4-6 weeks. Out of 1 ml blood (1 X 10(6) leukocytes) 1-10 stable clones were isolated, secreting specific anti-viral antibodies. These clones were fused with an aminopterin-sensitive, ouabain-resistant, non-immunoglobulin producing mouse-human hybridoma (Org MHH.1). From such fusions 10-90% of the cultures yielded viable hybridomas of which 45% produced antibodies with the same specificity as of the parental EBV transformant. Immunoglobulin production of both EBV transformants and hybridomas was shown to be stable for more than 6 months and at a concentration up to 100 micrograms X ml-1 X 48 h-1. Chimpanzee EBV-transformed lymphocytes proliferated excellently in vitro. Mouse-human hybridomas, however, could be more easily cultivated, cloned and scaled up than the parental EBV-transformed lymphocytes. In conclusion, stable, monoclonal antibody-secreting cell lines of either human or chimpanzee origin could be isolated with an efficiency that exceeds by 10-100-fold standard murine hybridoma technology.
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PMID:Human and chimpanzee monoclonal antibodies. 298 74

We have isolated a recombinant virus between the A59 and JHM strains of mouse hepatitis virus, which contain a single species of nonsegmented RNA genome. This recombinant was derived by mixed infection of DBT cells with temperature-sensitive mutants of A59 and JHM at nonpermissive temperature. Viruses recovered at this temperature were screened by oligonucleotide fingerprinting of their genomic RNAs. One recombinant virus, B1, was found to contain mostly A59-derived sequences, but the 3 kilobases at the 5' end of the genomic RNA was derived from JHM. Thus, the crossover point in the B1 genome is located within gene A, which codes for the viral RNA polymerases. The study of the intracellular RNA species of B1 virus revealed that probably all of the virus-specific subgenomic mRNA species contained the body sequences of strain A59 but the leader sequences of JHM. This result indicates that the JHM leader RNA, which differs from the A59 leader RNA, could be fused to the mRNAs of a different virus strain during RNA transcription. Furthermore, B1 virus-infected cells contain an additional subgenomic mRNA species which is transcribed from a new initiation site within gene C, suggesting that the leader RNA could determine the site of initiation for coronavirus mRNAs. These data represent a first report of RNA recombination between viruses, other than picornaviruses, which contain nonsegmented RNA genomes.
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PMID:Recombination between nonsegmented RNA genomes of murine coronaviruses. 299 67

Cell fusion induced by infection with mouse hepatitis virus strain A59 (MHV-A59) varied markedly in extent and time course in four different murine cell lines. When inoculated at a multiplicity of 3 to 5 PFU per cell, the Sac-, L2, and DBT cell lines began to fuse by 7 h, were fused into confluent syncytia by 9 to 12 h, and peeled from the substrate by 10 to 14 h. These virulent virus-cell interactions were in striking contrast to the moderate interaction of MHV-A59 with the 17 Cl 1 cell line, in which only small syncytia were observed 18 h postinoculation, and greater than 50% of the cells remained unfused by 24 h. The yield of infectious virus produced by 17 Cl 1 cells was 10-fold higher than the yields from the other three cell lines. The processing of the nucleocapsid protein, the membrane glycoprotein E1, and the peplomeric glycoprotein E2 were found to differ significantly in the four cell lines. Since the E2 glycoprotein is responsible for virus-induced cell fusion, we attempted to correlate differences in cellular processing of E2 with differences in fusion of infected cells. The predominant intracellular form of E2 in all cell lines was the 180K species. Pulse-chase experiments showed that a small portion of the 17 Cl 1 cell-associated 180K E2 was cleaved by 1 h after synthesis to yield 90K E2, shown in the preceding paper to consist of two different glycoproteins called 90A and 90B (L. S. Sturman, C. S. Ricard, and K. V. Holmes, J. Virol. 56:904-911, 1985). This cleavage occurred shortly before the release of virions from cells, as shown by pulse-chase experiments. After budding at intracellular membranes, virions released into the medium by the four cell lines contained different ratios of 180K to 90K E2. Virions from Sac- cells, which contained 100% 90K E2, fused L2 cells rapidly without requiring virus replication, whereas virions from 17 Cl 1 cells, which had 50% 90K E2, required trypsin activation to induce rapid fusion (Sturman et al., J. Virol. 56:904-911, 1985). The addition of protease inhibitors to the medium markedly delayed L2 cell fusion induced by MHV infection. The extent of coronavirus-induced cell fusion does not depend solely upon the percent cleavage of the E2 glycoprotein by cellular proteases, since extensive fusion was induced by infection of L2 and DBT cells but not 17 Cl 1 cells, although all three cell lines cleaved E2 to the same extent.(ABSTRACT TRUNCATED AT 400 WORDS)
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PMID:Proteolytic cleavage of the E2 glycoprotein of murine coronavirus: host-dependent differences in proteolytic cleavage and cell fusion. 299 44

The subgenomic RNAs of the fowl coronavirus infectious bronchitis virus (IBV) form a 3' co-terminal or 'nested' set. The presence of non-contiguous (leader) sequences fused to the 5' termini of murine hepatitis virus mRNAs has been demonstrated using RNase T1 oligonucleotide mapping and sequencing. The presence of a leader sequence on IBV mRNA A has been demonstrated previously. In this paper the presence of a leader identical to that present on the 5' terminus of IBV mRNA A is demonstrated to be present on the 5' terminus of IBV genomic RNA. This has been achieved by sequencing of primer extension products and cDNA clones containing the genomic leader. Analysis of these clones has revealed the presence of a sequence at the leader/genome-length RNA junction which is closely related to regions of homology identified previously within the genomic RNA sequence at the leader/body junctions of subgenomic RNAs. The implications of this finding for mechanisms of coronavirus RNA synthesis are discussed.
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PMID:Cloning and sequencing of 5' terminal sequences from avian infectious bronchitis virus genomic RNA. 300 36


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