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)

An essential factor for charting the evolution of hepadnaviruses is an estimation of the mutation rate of the virus genome during replication in the host. In order to determine the mutation rate of the hepadnavirus genome under defined experimental conditions, we transfected 10 neonatal woodchucks with an infectious molecular clone of woodchuck hepatitis virus (WHV). By 4 months post-transfection, all 10 animals showed serological evidence for WHV infection. Subsequently, 1 animal became chronically infected and was used for further study. At 16 months post-transfection WHV DNA from serum virions was cloned and the nucleotide sequence of three independent progeny genomes compared directly with that of the input recombinant DNA. Although the consensus nucleotide sequence remained unchanged, we found three differences in individual progeny genomes when compared to the parental genome sequence. Thus, we estimate the mutation rate of the WHV genome to be less than or equal to 2 X 10(-4) base substitutions/site/year. This figure is one to two orders of magnitude lower than the mutation rates previously calculated for the positive- and negative-strand RNA viruses, but is similar to the mutation rate of the gag gene which is the most slowly evolving gene of retroviruses. Therefore, we find that the hepadnavirus genome is relatively stable during replication in host tissues when compared to other viruses that lack polymerase-associated proofreading functions.
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PMID:Mutation rate of the hepadnavirus genome. 272 51

The aim of the present study was to determine, in a population of 70 HIV-1 infected patients with antibodies to HCV, the percentages of individuals with an active replication of HIV-1, HCV or both. During a one year follow-up of these patients at different stages of disease, blood samples were regularly collected for determination of transaminase, beta 2 microglobulin and CD4+ lymphocytes. Total RNAs were extracted from the sera, retrotranscribed with MoMuLV reverse transcriptase and nested PCR assays were carried out separately with sets of primers homologous to the 5' non-translated region of HCV and in HIV-1 gag. The amplified products were subjected to electrophoresis and observed under u.v. illumination after staining with ethidium bromide. For some samples, the identity of the amplified products was confirmed by Southern blotting by hybridization with enzyme-labelled probes. A total of 57% of the patients were found to produce HIV-1 RNA and 62% HCV RNA, while 34% produced both. HIV-1 RNA production was correlated with beta 2 microglobulin and CD4+ levels; active replication of HCV was correlated with hepatitis but not with CD4+ levels nor with HIV-1 RNA synthesis.
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PMID:HIV-1 and HCV co-infected patients: detection of active viral expression using a nested polymerase chain reaction. 790 23

Frequent occurrence of woodchuck hepatitis virus DNA (WHV DNA) integration into or in proximity to myc oncogenes and in the win locus of cellular genome in woodchuck hepatocellular carcinomas (HCC) has been described by several authors. We report a further cellular locus as a recurrent target for WHV integration in woodchuck HCCs. A WHV DNA integration and its cellular flanking regions were cloned from a HCC developed in a chronically WHV-infected woodchuck. Sequence analysis showed integration of rearranged C, PreS1, and 5' truncated X regions of the WHV genome, located in a cellular locus previously described for WHV integration in another woodchuck HCC. The two integration sites are only about 0.5 kb apart. In addition to Alu-like repeats and a gag-like coding region, previously described, we found several features of MAR (matrix attachment region) chromosomal sequences in the normal cellular locus, leading us to predict that part of it might be a previously unrecognized MAR.
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PMID:Recurrence of WHV integration in the b3n locus in woodchuck hepatocellular carcinoma. 852 20

In woodchuck hepatocellular carcinoma (HCC) the myc-oncogene family (particularly N-myc2) and the win locus of cellular genome have been reported as frequent targets for integration of woodchuck hepatitis virus (WHV) DNA. In this paper a further cellular locus, b3n, is reported as recurrent target for WHV integration in woodchuck HCC. Cloning and sequencing of a WHV-DNA integration and its cellular flanking regions showed that viral DNA was inserted in a chromosomal region already described for WHV integration in another single HCC. The two integration sites are only 0.5 kb apart. A link between WHV integration in b3n and HCC development may be postulated. Careful analysis of the sequence of the unoccupied locus revealed that, in addition to Alu-like repeats and a gag-like coding region, already described, several features of Matrix Attachment Region (MAR) sequences are present. Thus (part of) b3n might be a previously unrecognized MAR. Organization of the chromatin in functional domains and regulation of gene expression are some functions attributed to MAR sequences. The occurrence of WHV-DNA integration close to the same putative MAR in two different HCCs suggests that a mechanism of deregulation of MAR functions by WHV insertion might act in some liver tumors.
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PMID:Woodchuck hepatitis virus DNA integration in a common chromosomal region of the woodchuck genome in two independent hepatocellular carcinomas. 934 96

Scaffold or matrix attachment regions (S/MARs) are noncoding genomic DNA sequences displaying in vitro selective binding affinity for nuclear scaffold. They have been reported to be involved in the physical attachment of genomic DNA to the nuclear scaffold, and thus in the organization of the chromatin in functional loops or domains, and in the regulation of gene expression. In this work, we report the identification of an S/MAR in a woodchuck chromosomal locus, named b3n, previously described as a recurrent site of woodchuck hepatitis virus (WHV) DNA integration in woodchuck hepatocellular carcinoma (HCC). The 4.3-kb sequence of this locus contains several Alu-like repeats and a gag-like coding region with frameshift mutations. Computer analysis revealed the presence of a region with unusually high AT content, typical of most S/MARs, and of specific motifs (A boxes, T boxes, topoisomerase II sites, and unwinding elements) overlapping or in proximity to the region with high AT content, predicting that b3n might contain an S/MAR. Fragments of the b3n locus were isolated by conventional and inverse PCR techniques. In in vitro binding experiments with both heterologous and autologous scaffold preparations, a 592-bp fragment spanning the region rich in S/MAR features showed marked scaffold affinity, which was specific when autologous scaffolds were used. The presence of an S/MAR at the b3n locus and its nature as a recurrent WHV integration site in HCC suggest the involvement of S/MAR elements in some of the mechanisms leading to liver oncogenesis.
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PMID:Identification of scaffold/matrix attachment region in recurrent site of woodchuck hepatitis virus integration. 965 45

We present a systematic comparison of three modules that enhance expression from retroviral gene transfer vectors at a posttranscriptional level: (i) splice signals (SS) that create an intron in the 5' untranslated region; (ii) constitutive RNA transport elements (CTE), originally discovered in D-type retroviruses; and (iii) the posttranscriptional regulatory element of woodchuck hepatitis virus (WPRE). Here we show that enhancement of expression depends not only on the specific element, but also on the gene of interest, implying context-dependent activity of the RNA elements. Interestingly, different results were obtained for genes that normally require or do not require such control elements. Expression of the HIV-1 gag-protease gene, which normally depends on the viral export factor Rev, was strongly enhanced by an oligomeric CTE, while WPRE had only a marginal effect. On the other hand, both CTE and WPRE compensated for the lack of an intron in the expression of human beta-globin. In this case, the strongest stimulation of RNA production was observed when functional SS were combined with the WPRE. Both CTE and, in particular, WPRE also enhanced expression of cDNAs that do not normally require any such element (green fluorescent protein, human multidrug resistance-1). In this study, functional SS and WPRE acted in an additive manner, resulting in a 10-fold higher level of expression. Our results indicate that the described modules act on different levels of RNA processing, transport, and translation and that the correct choice of a posttranscriptional enhancer configuration depends on the type of cDNA to be expressed.
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PMID:Context dependence of different modules for posttranscriptional enhancement of gene expression from retroviral vectors. 1108 17

As major antigen-presenting cells and effectors in the maintenance of tolerance, dendritic cells (DCs) are key cells of the immune system and can thus be envisioned to have roles in immunotherapy strategies. We, and others, previously showed that simian immunodeficiency virus (SIV)-derived lentiviral vectors were able to deliver a gene into human differentiated DCs. We describe here the upgrading of the SIV vector system and the improvements of the transduction protocol, which allowed us to transduce more than 90% of human monocyte-derived DCs. We developed new SIV lentiviral vectors carrying SIV splice regulatory elements and either the woodchuck hepatitis virus regulatory element (WPRE) or the murine phosphoglycerate-kinase 1 (PGK) promoter. We show that insertion of the WPRE in the SIV vector is detrimental to gene transfer in DCs, while this sequence increases transgene expression in 293T cells. Using an optimized SIV vector, high levels of transgene expression were obtained in more than 30% of human DCs at a multiplicity of infection (MOI) of 1, and close to 100% using a MOI of 20. VSV-G pseudotyped vectors generated with only gag, pol, tat, and rev helper functions failed to transduce DCs. This defect was completely rescued when the SIV accessory gene vpx was provided in trans in vector-producing cells. Genetically modified DCs were shown to behave as bona fide DCs in both allogenic and autologous mixed leukocyte reactions. These findings allow us to propose an optimal system for efficient and safe DC transduction with improved SIV vectors.
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PMID:High levels of transduction of human dendritic cells with optimized SIV vectors. 1186 18

Gene transfer systems based on lentiviruses have emerged as promising gene delivery vehicles for human gene therapy due to their ability to efficiently transduce nondividing target cells. Both primate and nonprimate lentiviruses have been used for construction of lentiviral vectors. An early generation of gene transfer system based on bovine immunodeficiency virus (BIV) has been developed (R. D. Berkowitz, H. Ilves, W. Y. Lin, K. Eckert, A. Coward, S. Tamaki, G. Veres, and I. Plavec, 2001, J. Virol. 75, 3371-3382). In this study, we mapped the BIV Rev response element (RRE) to 312 bp of the Env coding region. Furthermore, we compared transduction efficiencies of vectors containing different portions of the BIV Gag coding region and found that the first 104 bp of gag contains a functional part of the BIV packaging signal. These findings enabled the generation of a minimal BIV-based lentiviral vector. The minimal transfer vector construct consists of a self-inactivating long terminal repeats (LTR), minimal packaging sequence, putative central polypurine tract, minimal RRE, an internal promoter driving the gene of interest, and a woodchuck hepatitis posttranscriptional regulatory element. In addition, we constructed a BIV packaging construct containing gag/pol, minimal Rev/RRE, and the accessory gene vpy. The regulatory gene tat and the accessory genes vif and vpw have been inactivated or truncated. The current system has significantly reduced regions of homologies between the transfer vector and the packaging constructs. The vectors generated from this system achieved a titer of greater than 1 x 10(6) transducing units per milliliter and are fully functional as indicated by their ability to efficiently transduce both dividing and nondividing cells. These modifications should provide improved safety features for the BIV-based gene transfer system.
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PMID:Mapping of the bovine immunodeficiency virus packaging signal and RRE and incorporation into a minimal gene transfer vector. 1249 Mar 99

Real-time PCR assays for nucleic acid testing (NAT) of hepatitis viruses A-E and for HIV-1 and HIV-2 have been developed; however, a multiplex assay that can simultaneously detect all of these agents is not yet available. Standardized TaqMan assays for detection of hepatitis viruses A-E have been described and applied to TaqMan Array Cards (TAC) which are capable of multiple pathogen detection using a single set of optimized PCR conditions. Assays for three gene regions of HIV-1 (long-terminal repeat (LTR), gag, and polymerase) and HIV-2 (overlap of LTR and gag, protease and integrase) were designed using the hepatitis assay conditions. Nucleic acid extracts of HIV-1-infected samples (44 plasma, 41 whole blood, 20 HIV-1 viral stocks) were tested on the TAC cards; 98 were reactive (92%) with 70 in multiple gene regions. Twenty-four of the 27 (89%) HIV-2 specimens (10 plasma, 1 PBMC lysate, 6 whole blood and 10 plasmids containing HIV-2 polymerase) were detected on TAC. No HIV or hepatitis virus sequences were detected in 30 HIV-negative samples (specificity 100%). Three HBV and 18 HCV co-infections were identified in the HIV-1-infected specimens. Multi-pathogen detection using TAC could provide a rapid, sensitive and more efficient method of surveying for a variety of infectious disease nucleic acids.
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PMID:Characterization of real-time microarrays for simultaneous detection of HIV-1, HIV-2, and hepatitis viruses. 2987 50