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)

The surface glycoprotein (S) of the murine hepatitis coronavirus MHV normally undergoes proteolytic cleavage during transport to the cell surface. To determine whether the cleavage of the MHV-JHM S glycoprotein is required to activate its ability to fuse cellular membranes, the protease recognition sequence in a cDNA copy of the S gene was altered from Arg-Arg-Ala-Arg-Arg into Ser-Val-Ser-Gly-Gly by site directed mutagenesis. The mutated and wild type S genes were expressed by means of recombinant vaccinia viruses and it could be shown that the mutated S protein was not cleaved when it was expressed in mouse DBT cells, in contrast to the wild type S protein. Nevertheless, the non-cleaved S protein induced extensive syncytium formation in mouse DBT cells. These results clearly indicate that the non-cleaved form of the MHV S protein is able to mediate cell membrane fusion. Thus, proteolytic cleavage is not an absolute requirement for its fusion function.
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PMID:Proteolytic cleavage of the murine coronavirus surface glycoprotein is not required for its fusion activity. 820 24

The main objective of this study was to determine the applicability of the polymerase chain reaction (PCR) to detection of hepatitis E virus (HEV) in sewage treatment plants and establishment of the prevalence of hepatitis viral diseases in a population. Epidemics of HEV infection because of inadequate public sanitation have been reported in several developing countries. A procedure for concentration of HEV in sewage samples through adsorption to membrane filters, elution with urea-arginine phosphate buffer, and subsequent reconcentration with magnesium chloride enabled us to concentrate HEV to volumes in the microliter range. HEV-specific cDNA was prepared by reverse transcription of the total RNA extracted from samples. Specific DNA amplification by PCR in combination with slot blot hybridization was used to demonstrate the presence of HEV in sewage samples from the inlets and outlets of three sewage treatment plants. The assay was specific for HEV, and a 240-bp amplified product was visualized by ethidium bromide fluorescence. Sewage samples adjusted to pH 5.0 for adsorption of viruses to membrane filters were PCR positive, while samples adjusted to pH 3.5 were PCR negative.
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PMID:Detection of hepatitis E virus in raw and treated wastewater with the polymerase chain reaction. 836 44

A cDNA copy of the murine coronavirus [otherwise known as murine hepatitis virus (MHV)] surface (S) glycoprotein gene was isolated and expressed in DBT cells by using a recombinant vaccinia virus system. The expressed S protein induced extensive syncytium formation at neutral pH. Oligonucleotide mutagenesis was used to engineer an S protein gene in which codons for the proteolytic cleavage site, Arg-Arg-Ala-Arg-Arg, were replaced with an equal number of codons for amino acids with aliphatic or aliphatic hydroxyl side-chains. The mutated S protein was stably expressed in DBT cells and, in contrast to the wild-type protein, was not proteolytically cleaved. Nevertheless, the non-cleaved protein induced extensive syncytium formation. These results clearly indicate that the non-cleaved form of the MHV S protein is able to mediate cell membrane fusion. Thus proteolytic cleavage is not an absolute requirement for fusion activity.
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PMID:Proteolytic cleavage of the murine coronavirus surface glycoprotein is not required for fusion activity. 838 59

B cells from nonimmune mice mediate the cytolysis of fibroblasts infected with the coronavirus, mouse hepatitis virus (MHV), strain A59. In this investigation, we report that splenic B cells and a B cell hybridoma induced the fragmentation of MHV-infected target cell DNA into a nucleosomal ladder pattern, characteristic of apoptosis. To determine the mechanism by which B cells mediated this killing event, we used criteria previously established for the killing of target cells by cytotoxic T lymphocytes (CTLs) and compared this B-cell-mediated killing to lymphocytic choriomeningitis virus (LCMV)-specific CTL killing of LCMV-infected target cells. Unlike CTL-mediated cytotoxicity, B cells efficiently lysed and induced the fragmentation of the DNA in their target cells in the presence of EGTA, arguing against a Ca(2+)-dependent granule exocytosis model for killing. In addition, paraformaldehyde-fixed B cells were able to kill MHV-infected targets. We were unable to detect TNF-alpha-associated cytotoxicity via bioassay with nonimmune effector B cells against the TNF-sensitive cell line, LM, or the TNF-alpha-resistant subline, L929.w, infected with MHV. Serine esterase inhibitors (benzamidine hydrochloride and N alpha-p-tosyl-L-arginine methyl ester) blocked CTL-induced 51Cr release and DNA fragmentation. In contrast, the inhibitors did not block the B-cell-induced 51Cr release, but did cause an inhibition in the fragmentation of the DNA of the target cell. These data indicate that B cells are capable of inducing the lysis and DNA fragmentation of MHV-infected target cells similar to CTL-induced apoptosis. However, we show that the mechanism(s) by which these processes are induced by B cells is distinct from CTL-mediated cytotoxicity.
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PMID:B cells induce apoptosis via a novel mechanism in fibroblasts infected with mouse hepatitis virus. 839 6

Hepatitis delta antigen (HDAg) is an RNA-binding protein with binding specificity for hepatitis delta virus (HDV) RNA (J. H. Lin, M. F. Chang, S. C. Baker, S. Govindarajan, and M. M. C. Lai, J. Virol. 64:4051-4058, 1990). By amino acid sequence homology search, we have identified within its RNA-binding domain two stretches of an arginine-rich motif (ARM), which is present in many prokaryotic and eukaryotic RNA-binding proteins. The first one is KERQDHRRRKA and the second is EDEKRERRIAG, and they are separated by 29 amino acids. Deletion of either one of these ARM sequences resulted in the total loss of the in vitro RNA-binding activity of HDAg. Thus, HDAg is different from other RNA-binding proteins in that it requires two ARM-like sequences for its RNA-binding activity. Replacement of the spacer sequence between the two ARMs with a shorter stretch of sequence also reduced RNA binding in vitro. Furthermore, site-specific mutations of the basic amino acid residues in both ARMs resulted in the total loss or reduction of RNA-binding activity. The biological significance of the RNA-binding activity was studied by examining the trans-activating activity of the RNA-binding mutants. The plasmids expressing HDAgs with various mutations in the RNA-binding motifs were cotransfected with a replication-defective HDV dimer cDNA construct into COS cells. It was found that all the HDAg mutants which had lost the in vitro RNA-binding activity also lost the ability to complement the defect of HDV RNA replication. We conclude that the trans-activating function of HDAg requires its binding to HDV RNA.
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PMID:RNA-binding activity of hepatitis delta antigen involves two arginine-rich motifs and is required for hepatitis delta virus RNA replication. 844 29

We clarified the clinical and immunogenetical differences between patients with autoimmune hepatitis (AI-CAH), and patients with type C chronic active hepatitis (C-CAH) and type B chronic active hepatitis (B-CAH) who were positive for autoantibodies and hyperglobulinemia. While histories of blood transfusion, intravenous drug abuse and tattoo were seen frequently in patients with type C-CAH, they were rare in patients with AI-CAH. The severe subjective symptoms including anorexia, lethargy, icterus, high fever and extrahepatic manifestations, and severe abnormality of biochemical data were seen in AI-CAH predominantly. Ongoing or past infection of HCV was seen in only 14% of patients with AI-CAH. HLA-DR4 was the most frequently associated with AI-CAH (89%) and 6 DR4-negative patients were positive for DR2. HLA-DNA typing showed that there was no significant difference in the frequency of DR4-associated Dw-alleles between the patients and controls who were positive for DR4. These findings suggest that the basic amino acid at position 13, which is present only on the DR2 and DR4 B1 molecules (Arg on DR2 and His on DR4), may contribute to the susceptibility to autoimmune hepatitis of Japanese. Thus, we conclude that AI-CAH is a genetically restricted, disease, and different from C-CAH which is a viral infectious disease.
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PMID:Comparison of the clinical and immunogenetic features between patients with autoimmune hepatitis and patients with type C chronic active hepatitis. 848 32

A new method is described for the characterization of RNA binding domains of a protein and applied to the study of the interaction between proteins and nucleic acid of the human hepatitis delta virus (HDV). The method uses synthetic peptides coated onto an ELISA plate and tested for their ability to bind digoxigenin-labelled RNAs. RNA binding is quantified with peroxidase-conjugated anti-digoxigenin. The hepatitis delta antigen (HDAg) is an RNA-binding protein that specifically binds HDV RNAs. In a previous study, it was shown that HDAg sequences corresponding to residues 2-27 and 79-107 bound to both genomic and antigenomic strands. Further investigations are reported on HDAg/HDV RNA binding, using additional HDAg peptides and the full-length HDV genomic and antigenomic strands. In order to validate the method, the efficiency of peptide coating onto the ELISA plate was assessed with human antibodies against HDAg. The two arginine-rich motifs potentially involved in the RNA-binding activity (97-107 and 136-146) were explored and the residues 2-27 and 79-211 were mapped using synthetic peptides. Only peptides corresponding to residues 2-17, 2-27, 79-107 and 84-126 of the HDAg bound to the genomic and antigenomic strands. The second arginine-rich motif represented by peptides 130-144 and 128-152 did not bind to HDV RNAs in this assay. This second arginine-rich domain may be involved in this interaction without a direct ability to bind HDV RNAs.
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PMID:Direct investigation of protein RNA-binding domains using digoxigenin-labelled RNAs and synthetic peptides: application to the hepatitis delta antigen. 860 3

The hepatitis delta virus large antigen (lHDAg) is a virally encoded protein that contains a prenylation signal sequence at its carboxyl terminus consisting of the tetrapeptide Cys-Arg-Pro-Gln. Although the presence of the Gln as the COOH-terminal residue generally specifies addition of the 15-carbon farnesyl isoprenoid, earlier reports had suggested that the protein is modified by the 20-carbon geranylgeranyl. The prenylation of lHDAg was examined in vitro using a fusion protein between glutathione S-transferase and the COOH-terminal 117 amino acids of lHDAg (GST-lHDAg). When recombinant GST-lHDAg was incubated with bovine brain cytosol in the presence of either farnesyl diphosphate or geranylgeranyl diphosphate, GST-lHDAg was preferentially farnesylated. Geranylgeranylation of the fusion protein was also observed, although at a rate considerably less than that of farnesylation. Using purified recombinant protein prenyltransferases, GST-lHDAg was found to be an excellent substrate (apparent Km = 0.8 microM) for protein farnesyltransferase (FTase), while modification by protein geranylgeranyltransferase I (GGTase I) was not detected. FTase was also able to catalyze geranylgeranylation of GST-lHDAg at a very low rate, suggesting that the low level of geranylgeranylation of GST-lHDAg observed in cytosolic preparations was mediated by FTase. Consistent with our observations on the in vitro prenylation of the GST-lHDAg fusion protein, isoprenoid analysis of authentic lHDAg expressed in COS cells demonstrated that the protein was farnesylated. Geranylgeranylation of lHDAg expressed in COS cells was not observed. As prenylation of lHDAg is required for the assembly of the hepatitis delta viral particle, these results suggest that inhibitors of FTase may be useful therapeutic agents for treatment of delta virus infection.
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PMID:The hepatitis delta virus large antigen is farnesylated both in vitro and in animal cells. 861 11

We describe three children with transaminase elevations and hepatic insufficiency who were given the diagnosis of cryptogenic hepatitis after the more common viral and metabolic diseases of the liver had been excluded. However, further laboratory investigations showed hyperammonemia, low blood urea levels, elevated plasma glutamine levels, and low citrulline levels. Urinary excretion of orotic acid was higher than normal, with absent urinary homocitrulline and normal fractional tubular reabsorption of lysine, ornithine, and arginine. These findings suggest the diagnosis of ornithine transcarbamylase deficiency. We emphasize the importance of investigating possible urea cycle disorders by determining ammonia plasma levels, both at baseline and after a protein load; urinary and plasma amino acids; and urinary orotic acid in all patients with liver disease of indeterminate etiology.
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PMID:Cryptogenic hepatitis masking the diagnosis of ornithine transcarbamylase deficiency. 873 1

The polymerase gene of Mouse Hepatitis Virus strain JHM (MHV-JHM) encodes a polyprotein larger than 750 kilodaltons. This polyprotein is proposed to be processed by several viral proteinases into functional subunits. The amino-terminal subunit is p28, which is cleaved by the first viral papain-like proteinase domain. In this study, we identified the cleavage site of this papain-like cysteine proteinase by amino acid sequencing of radiolabeled polypeptide adjacent to p28. Proteolysis occurs between the glycine-247 and valine-248 dipeptide bond. To determine which amino acid residues are critical for proteolysis, we preformed site-directed mutagenesis on the coding sequences surrounding the cleavage site and assayed for the efficiency of cleavage of p28 in an in vitro transcription and translation system. We report that glycine-247 and arginine-246 are the most critical residues for efficient processing of p28.
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PMID:Proteolytic processing of the MHV polymerase polyprotein. Identification of the P28 cleavage site and the adjacent protein, P65. 883 May 20


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