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)

High rates of genetic variation ensure the survival of RNA viruses. Although this variation is thought to result from error-prone replication, RNA viruses must also maintain highly conserved genomic segments. A balance between conserved and variable viral elements is especially important in order for viruses to avoid "error catastrophe." Ribavirin has been shown to induce error catastrophe in other RNA viruses. We therefore used a novel hepatitis C virus (HCV) replication system to determine relative mutation frequencies in variable and conserved regions of the HCV genome, and we further evaluated these frequencies in response to ribavirin. We sequenced the 5' untranslated region (5' UTR) and the core, E2 HVR-1, NS5A, and NS5B regions of replicating HCV RNA isolated from cells transfected with a T7 polymerase-driven full-length HCV cDNA plasmid containing a cis-acting hepatitis delta virus ribozyme to control 3' cleavage. We found quasispecies in the E2 HVR-1 and NS5B regions of untreated replicating viral RNAs but not in conserved 5' UTR, core, or NS5A regions, demonstrating that important cis elements regulate mutation rates within specific viral segments. Neither T7-driven replication nor sequencing artifacts produced these nucleotide substitutions in control experiments. Ribavirin broadly increased error generation, especially in otherwise invariant regions, indicating that it acts as an HCV RNA mutagen in vivo. Similar results were obtained in hepatocyte-derived cell lines. These results demonstrate the potential utility of our system for the study of intrinsic factors regulating genetic variation in HCV. Our results further suggest that ribavirin acts clinically by promoting nonviable HCV RNA mutation rates. Finally, the latter result suggests that our replication model may be useful for identifying agents capable of driving replicating virus into error catastrophe.
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PMID:Viral RNA mutations are region specific and increased by ribavirin in a full-length hepatitis C virus replication system. 1216 70

According to two highly conserved genome sequences within the helicase(NS3) region and 5'-uncoding(5' UTR) region, we designed two sets of primer pairs to detect HGV RNA by RT-nested PCR in order to study HGV infection in Chinese population. Three hundred and fifty-four serum specimens of various liver diseases were collected from Beijing, Qin Huangdao and Henan areas. Seventy-nine out of 354(22.3%) specimens were HGV RNA positive. Among 254 known clinical hepatitis/liver disease samples, 50(19.6%) were HGV RNA positive. Thirteen HGV RNA positive samples(30.2%) were derived from 43 cryptogenic or nonA-E hepatitis. In 57 commercial blood donors who were antibody positive to HCV 16(30.2%) were HGV RNA positive, suggesting HGV infection is common in various population. It may be an etiological factor which leads to nonA-E hepatitis and post-transfusion hepatitis.
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PMID:[Detection of hepatitis G virus infection among clinical patients with hepatitis/liver diseases in China by reverse transcription-nested polymerase chain reaction]. 1251 1

The aim of this article is to study the prevalence of GBV-C/HGV in patients with liver diseases and the clinical features in patients with (GBV-C/HGV infection. The serum samples were obtained from 169 patients with liver diseases in You An Hospital). Serum GBV-C/HGV RNA was detected by reverse transcription nested polymerase chain reaction (RT-nPCR) using two primer pairs of 5' untranslated region (5' UTR) of HGV. Serum anti-HGV was detected by ELISA simultaneously. The partial GBV-C/HGV genome isolated from one patient was cloned into T vectors and sequenced by dideoxy-mediated chain termination methods. Among 169 patients with various liver diseases, the GBV-C/HGV RNA positive rate was 9.5% (16/169), including 11.1% (1/9) of AHA, 4.1% (3/73) of CHB, 16.2% (6/37) of CHC, 13.3% (2/15) of AH(nonA-E) 12.5% (1/8) of CH(nonA-E) 15.4% (2/13) of LC and 33.3% (1/3) of SH cases. Of 29 patients having a history of surgical operation and transfusion, 9(31.0%) was positive for GBV-C/HGV RNA, which was remarkably higher than those cases without surgical operation and transfusion. The sequence analysis showed that there was 89.14%-98.91% nucleotide identity between our isolate and published GBV-C/HGV isolates. The results also suggested that infection rate of GBV-C/HGV was around 9.5% in patients from Beijing region, patients with GBV-C/HGV infection might show various clinical features and GBV-C/HGV might not be the major cause of hepatitis nonA-E.
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PMID:[Detection of GBV-C/HGV infection in patients with liver diseases]. 1252 49

Background A new hepatitis-associated RNA virus, belonging to the Flaviviridae, has been recently discovered and called HGV (GBV-C). This virus has been shown to be transmitted parenterally. In this study we examined a group of children born to HCV infected women. Methods Between September 1994 and December 1998, we studied a cohort of 53 pregnant women, aged between 20 and 43 years. They were all HCV Ab and HCV RNA positive, with a diagnosis of chronic hepatitis. One patient was HbsAg positive and 4 patients (pts.) (7.5%) were HIV Ab positive. Anamnestic information revealed that: 28 pts. (52.8%) were IVDUs, 11 pts. (20.8%) had been haemotransfused and 14 pts. (26.4%) had no risk factors. We examined HGV RNA by RT nested PCR, using primers from the 5'UTR of HGV. Anti-HGV antibodies (anti-E2) were detected with an ELISA test using recombinant E2 protein. Ten of the 53 pregnant women (18.9%) were HGV RNA positive (32 other pts., 60.4%, were positive for anti-E2 antibodies). We monitored their children for 18-24 months (with clinicai and haematological controls), looking for HGV RNA, anti-E2 antibodies, HCV RNA and for ALT serum levels. Results Seven (70%) new-bom children proved HGV RNA positive at follow-up; all babies were HCV RNA negative at controls. Four of them were born vaginally; none of them was breast-fed. HGV RNA was first detectable at the 3rd month of life in 3 babies, and all babies were HGV RNA positive at the 6th month of life. Six babies (85.7%) remained positive during the observation period. One baby (14.3%) seroconverted at 10 months, developing anti E-2 antibodies and becoming HGV RNA negative. Four babies (57.1%) maintained normal ALT serum levels during the whole follow-up period, while 3 patients showed a low increase in ALT serum levels. The ALT values normalised at later controls. Conclusions HGV infection shows a very high (70%) rate of vertical transmission but a low and doubtful pathogenicity with asymptomatic evolution in babies. Patients who did not develop anti-E2 antibodies at the 12th month of life remained infected without persistent signs of hepatic failure.
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PMID:[Evolution of hepatitis G in children with vertically transmitted HGV] 1270 18

The use of lentiviral vectors for basic research and potential future clinical applications requires methodologies that can accurately determine lentiviral titers and monitor viral transgene expression within target cells, beyond the context of reporter genes typically used for this purpose. Here we describe a quantitative RT-PCR (qRT-PCR) method that achieves both goals using primer sequences that are specific for the woodchuck hepatitis virus posttranscriptional regulatory element (WPRE), an enhancer contained in many retroviral vectors and that is incorporated in the 3' UTR of nascent transgene transcripts. Quantitation of titers of three recombinant lentiviruses, genetically identical except for the transgene, demonstrated consistent differences in titer that were likely due to transgene-associated toxicity in producer cells and target cells. Viruses encoding the tumor-associated antigens tyrosinase and neo-poly(A) polymerase yielded reproducibly lower titers than a virus encoding enhanced green fluorescent protein (GFP) at the viral RNA, integrated DNA, and transgene mRNA levels, as measured by WPRE qPCR. Furthermore, the magnitude of differences in expression of the three transgenes in transduced target cells could not have been predicted by measuring vector DNA integration events. Since transgene expression in target cells is the most common goal of lentiviral transduction, and since methods to quantify transgene expression on the protein level are not always readily available, qRT-PCR based on a nucleotide sequence included in the transcript provides a useful tool for titering novel recombinant lentiviruses.
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PMID:Real-time quantitative reverse transcriptase-polymerase chain reaction as a method for determining lentiviral vector titers and measuring transgene expression. 1271 61

5' and 3' UTR sequences on the coronavirus genome are known to carry cis-acting elements for DI RNA replication and presumably also virus genome replication. 5' UTR-adjacent coding sequences are also thought to harbor cis-acting elements. Here we have determined the 5' UTR and adjacent 289-nt sequences, and 3' UTR sequences, for six group 2 coronaviruses and have compared them to each other and to three previously reported group 2 members. Extensive regions of highly similar UTR sequences were found but small regions of divergence were also found indicating group 2 coronaviruses could be subdivided into those that are bovine coronavirus (BCoV)-like (BCoV, human respiratory coronavirus-OC43, human enteric coronavirus, porcine hemagglutinating encephalomyelitis virus, and equine coronavirus) and those that are murine hepatitis virus (MHV)-like (A59, 2, and JHM strains of MHV, puffinosis virus, and rat sialodacryoadenitis virus). The 3' UTRs of BCoV and MHV have been previously shown to be interchangeable. Here, a reporter-containing BCoV DI RNA was shown to be replicated by all five BCoV-like helper viruses and by MHV-H2 (a human cell-adapted MHV strain), a representative of the MHV-like subgroup, demonstrating group 2 common 5' and 3' replication signaling elements. BCoV DI RNA, furthermore, acquired the leader of HCoV-OC43 by leader switching, demonstrating for the first time in vivo recombination between animal and human coronavirus molecules. These results indicate that common replication signaling elements exist among group 2 coronaviruses despite a two-cluster pattern within the group and imply there could exist a high potential for recombination among group members.
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PMID:Common RNA replication signals exist among group 2 coronaviruses: evidence for in vivo recombination between animal and human coronavirus molecules. 1459 69

RNA virus genomes contain cis-acting sequence and structural elements that participate in viral replication. We previously identified a bulged stem-loop secondary structure at the upstream end of the 3' untranslated region (3' UTR) of the genome of the coronavirus mouse hepatitis virus (MHV). This element, beginning immediately downstream of the nucleocapsid gene stop codon, was shown to be essential for virus replication. Other investigators discovered an adjacent downstream pseudoknot in the 3' UTR of the closely related bovine coronavirus (BCoV). This pseudoknot was also shown to be essential for replication, and it has a conserved counterpart in every group 1 and group 2 coronavirus. In MHV and BCoV, the bulged stem-loop and pseudoknot are, in part, mutually exclusive, because of the overlap of the last segment of the stem-loop and stem 1 of the pseudoknot. This led us to hypothesize that they form a molecular switch, possibly regulating a transition occurring during viral RNA synthesis. We have now performed an extensive genetic analysis of the two components of this proposed switch. Our results define essential and nonessential components of these structures and establish the limits to which essential parts of each element can be destabilized prior to loss of function. Most notably, we have confirmed the interrelationship of the two putative switch elements. Additionally, we have identified a pseudoknot loop insertion mutation that appears to point to a genetic interaction between the pseudoknot and a distant region of the genome.
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PMID:Characterization of the RNA components of a putative molecular switch in the 3' untranslated region of the murine coronavirus genome. 1469 98

The rhesus macaque ( Macaca mulatta) has become a popular animal model for several human infectious diseases, such as HIV (modeled by SIV infection), hepatitis, and malaria. Investigation of T-cell responses in experimental infectious diseases in rhesus macaques has benefited from an expanding understanding of the diversity of macaque MHC class I heavy chains and the restriction of antigen presentation by macaque class I molecules. Here we add to this understanding with the first nucleotide sequences of M. mulatta beta(2)-microglobulin (beta(2)m) mRNA, including a portion of the 3'-untranslated region (3'UTR). In pairwise comparison, the beta(2)m protein of M. mulatta differs from human and chimpanzee beta(2)m by nine amino-acid substitutions (92% identity), and from Macaca fascicularis by one amino-acid difference in the signal peptide region (99% identity). Allelic variations were identified at one site in the 3'UTR. A structural analysis of human or chimpanzee beta(2)m and M. mulatta beta(2)m suggests that the differences cluster in three solvent-exposed clusters and do not involve contacts with the class I heavy chain. We predict that human and macaque beta(2)m should bind interchangeably with the class I heavy chains of the other species, and show that four M. mulatta class I alleles form cell surface complexes with human beta(2)m. Further, we predict that W6/32 (a monoclonal antibody that recognizes a combined epitope of some class I heavy chains and beta(2)m with a subtle species dependence) should bind similarly human or macaque class I molecules that are bound with beta(2)m of either species, supported by evidence of recognition of both heterologous and homologous complexes of macaque class I heavy chains. Our findings contribute to the growing understanding of rhesus macaque histocompatibility antigens and antigen presentation, and to the phylogeny of beta(2)m in primates.
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PMID:Sequence of beta(2)-microglobulin from rhesus macaque ( Macaca mulatta) includes an allelic variation in the 3'-untranslated region. 1496 20

The 3' untranslated region (3' UTR) of the genome of the severe acute respiratory syndrome coronavirus can functionally replace its counterpart in the prototype group 2 coronavirus mouse hepatitis virus (MHV). By contrast, the 3' UTRs of representative group 1 or group 3 coronaviruses cannot operate as substitutes for the MHV 3' UTR.
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PMID:The 3' cis-acting genomic replication element of the severe acute respiratory syndrome coronavirus can function in the murine coronavirus genome. 1522 Apr 62

Three RNA features have been identified that elevate retroviral transgene expression: an intron in the 5' untranslated region (5'UTR), the absence of aberrant translational start codons and the presence of the post-transcriptional regulatory element (PRE) of the woodchuck hepatitis virus in the 3'UTR. To include such elements into self-inactivating (SIN) vectors with potentially improved safety, we excised the strong retroviral promoter from the U3 region of the 3' long terminal repeat (LTR) and inserted it either downstream or upstream of the retroviral RNA packaging signal (Psi). The latter concept is new and allows the use of an intron in the 5'UTR, taking advantage of retroviral splice sites surrounding Psi. Three LTR and four SIN vectors were compared to address the impact of RNA elements on titer, splice regulation and transgene expression. Although titers of SIN vectors were about 20-fold lower than those of their LTR counterparts, inclusion of the PRE allowed production of more than 10(6) infectious units per ml without further vector optimizations. In comparison with state-of-the-art LTR vectors, the intron-containing SIN vectors showed greatly improved splicing. With regard to transgene expression, the intron-containing SIN vectors largely matched or even exceeded the LTR counterparts in all cell types investigated (embryonic carcinoma cells, fibroblasts, primary T cells and hematopoietic progenitor cells).
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PMID:Self-inactivating retroviral vectors with improved RNA processing. 1537 67


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