Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound

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Query: EC:2.7.7.49 (reverse transcriptase)
31,746 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

MRC-5 human diploid cells infected with Simian Sarcoma Virus from woolly monkey (SSV-1) were not transformed but an efficient replication of non transforming SiLV was demonstrated. Increase of virus reverse transcriptase activity paralleled cell replication during successive passages. Preliminary results concerning the influence of viral infection on the life span and the karyotype of MRC-5 diploid cells will be reported and several implications of these findings discussed.
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PMID:Replication of primate oncornavirus SSV-1 on MRC-5 human diploid cells. 7 83

Fv-1b restriction in BALB/3T3 cells is temporarily abrogated following infection with N-tropic murine leukemia virus. The mechanism of this phenomenon was investigated by comparing the inactivation rates for viral infectivity and for the ability of the same virus to abrogate Fv-1 restriction. Inactivation of the abrogating ability of N-tropic murine leukemia virus following graduated doses of gamma radiation proceeded at half the rate of that for viral infectivity. This result indicates that viral RNA must function in abrogating Fv-1b restriction but that only a portion of the viral genome is required. The inactivation kinetics of N-tropic murine leukemia virus were also determined following incubation of virus at 43 degrees C. Abrogating ability of N-tropic murine leukemia virus was found to be about six times as stable under these conditions as was viral infectivity. Interestingly, virion-associated reverse transcriptase activity was inactivated at the same rate as was viral infectivity, indicating that this enzyme may not need to function during abrogation. Virus heated at 43 degrees C was used to study the kinetics of the abrogation phenomenon itself. Abrogation was shown to be transient, requiring 6 to 9 h after virus infection to become maximally effective and beginning to disappear after about 18 h. The data reported here confirm the idea that abrogation of Fv-1 restriction can be separated experimentally from virus replication, and they raise the possibility that a separate biochemical pathway exists for incoming viral RNA in Fv-1 restrictive cells.
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PMID:Abrogation of Fv-1b restriction with murine leukemia viruses inactivated by heat or by gamma irradiation. 7 8

[3H]Uridine-labeled Rauscher leukemia virus was used to infect mouse embryo fibroblasts. After the infected cells were separated into nuclear and cytoplasmic fractions nucleic acid was extracted by sodium dodecyl sulfate-phenol-chloroform treatment and analyzed by Cs2SO4 and sucrose density gradient centrifugation. Between 45 and 70 min after infection a transient and synchronized shift of the acid-insoluble radioactive peak toward the RNA-DNA hybrid region occurred in both the nuclear and cytoplasmic fractions. The density of the cytoplasmic hybrid shifted to 1.56 g/ml (RNA equals about 50%), while the sedimentation rate decreased from 36 S to 14 S; however, the density of the nuclear hybrid shifted to 1.58-1.48 g/ml (RNA equals 57-17%, respectively), while its sedimentation rate remained about 65 S. The hybrids in both the nuclear and the cytoplasmic fractions still showed hybrid density after heat denaturation. The processes of the early stages of RNA tumor virus infection are discussed with regard to the functions of viral RNA-dependent DNA polymerase (reverse transcriptase) and a possible integration of viral genetic information into the host chromosome.
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PMID:Fate of viral RNA of murine leukemia virus after infection. 16 22

Cultured synovial cells from 8 patients with rheumatoid arthritis (RA) and 7 subjects without joint disease were assayed and comapred for RNA-directed and DNA-directed DNA polymerase activity. No activity was found in either RA or control specimens using a synthetic RNA template that specificically detects oncornavirus RNA-directed DNA polymerase. The DNA-directed DNA polymerase activity of RA specimens was increased (P less than 0.10) in the high-speed pellet fraction of cell lysates. The possible relationship of these finding to virus infection in RA is disscussed.
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PMID:DNA polymerase activity of cultured rheumatoid synovial cells. 16 46

The experiments described show that inoculation of two monkey species, M. arctoides and P. hamadryas, with human leukaemic blood or its filtrates causes a viral disease with the characteristics of malignant lymphoma of mixed type. The disease was passed in subsequent passages. The virus was isolated and identified as an oncornavirus of C-type by its characteristic morphological appearance and buoyant density (1.16 g/cm3 in sucrose and 1.21 g/cm3 in caesium chloride), and by the presence of 60-70S RNA and RNA-dependent DNA polymerase. There is some evidence that it differs immunologically from other known oncornaviruses of mammals including primates. It is postulated that both horizontal and vertical transmission of this oncornavirus can occur.
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PMID:Transmission of human leukaemia to nonhuman primates. 17 Jun 20

We studied the transformation of epithelial, diploid cell lines (RL-33 and RL-34) derived from W rat liver by the Kirsten murine sarcoma virus. On days 4-5 after virus infection, the epithelial cells began to pile up focally, forming small projections and releasing round cells from the foci. The epithelial cells grew in chains or as islets and grew in suspension above the cells attached to the bottom of the flasks when the cultures reached the confluent stage. The virus titration pattern was "one-hit." Three classes of transformed cells were isolated with respect to virus release and antigen expression: 1) virus producer, 2) non-producer, and 3) sarcoma-positive, leukemia-negative cells. When transplanted sc into newborn rats, the transformed cells produced sarcomas. The transformed cells formed within 1-3 days larger aggregates than those of their normal counterpart cells when suspended in liquid growth medium above an agar base. Aggregate properties (size, viability, and proliferation) of transformed cells correlated with growth in soft agar and tumorigenicity. RNA-dependent DNA polymerase and type C virus particles were readily induced in the normal rat liver epithelial cells after exposure to 5-iodo-2'-deoxyuridine.
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PMID:Transformation of rat liver epithelial cells by Kirsten murine sarcoma virus. 19 67

On theoretical grounds we propose that the essential step in the development of subacute sclerosing panencephalitis (SSPE) after measles virus infection involves a reverse transcriptase-mediated change to a DNA form, probably brought about by co-infection with a leukovirus at a critical point in time. We further suggest that this new DNA then replicates either as the core of a new slow virus or as a membrane-attached viroid exhibiting a form of non-structural integration with host cell DNA resembling that found with the herpes viruses.
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PMID:The relationship between measles virus infection and subacute sclerosing panencephalitis (SSPE). 93 14

Various polyoxometalates proved inhibitory to the replication of a number of enveloped DNA and RNA viruses, i.e., herpesviruses (herpes simplex and cytomegalo), togaviruses (Sindbis), paramyxoviruses (respiratory syncytial), rhabdoviruses (vesicular stomatitis), arenaviruses (Junin and Tacaribe), and retroviruses [human immunodeficiency virus type 1 (HIV-1) and type 2 (HIV-2), simian immunodeficiency virus, and murine sarcoma virus]. The most potent compounds, i.e., JM1590 [K13[Ce(SiW11O39)2]. 26H2O] and JM2766 [K6[BGa(H2O)W11O39]. 15H2O], inhibited HIV-1 and simian immunodeficiency virus at concentrations as low as 0.008-0.8 microM. The polyoxometalates also inhibited giant cell formation in co-cultures of HIV-infected HUT-78 cells and uninfected MOLT-4 cells. Studies designed to unravel the mechanism of action of these compounds revealed that they inhibit the reverse transcriptase activity associated with HIV. The polyoxometalates also proved inhibitory to the binding of HIV-1 virions to the cells. From "time of addition" experiments, whereby the polyoxometalates were added at different times after virus infection, their mechanism of anti-HIV action could be attributed to inhibition of virus-cell binding. There was a good correlation (r = 0.84) between the inhibitory effects of the compounds on HIV-1-induced cytopathicity and their inhibitory effects on syncytium formation and a close correlation (r = 0.902) between their inhibitory effects on syncytium formation and their interaction with gp120, whereas there was no correlation between their anti-HIV-1 activity and their inhibitory effects on HIV-1 reverse transcriptase. In flow cytometric studies, the compounds did not interfere with the binding of OKT4A/Leu-3a monoclonal antibody to the CD4 receptor of uninfected cells, but they inhibited binding of anti-gp120 monoclonal antibody to HIV-1-infected cells. Thus, the binding of the polyoxometalates to the viral envelope glycoprotein gp120 is responsible for their anti-HIV activity.
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PMID:Mechanism of anti-human immunodeficiency virus action of polyoxometalates, a class of broad-spectrum antiviral agents. 128 64

To investigate the etiologic agent associated with Kawasaki disease (KD), we initially established a cocultivation system using concanavalin A (Con A)-stimulated lymphoblastoid cells obtained from each retrovirus-seronegative individual's peripheral blood mononuclear cells (MNCs) cocultivated with each of 1) 40 patients with KD, 2) 10 patients with other viral infection and skin rash, and 3) 10 age- and sex-matched normal controls. Five major findings suggested that virus-like particles with reverse transcriptase (RT) activity are associated with KD. First, RT activity appeared significantly higher on day 12 after the onset of fever in the KD patients than in those with other viral infections and normal controls (dTMP incorporation: 3,645 +/- 248 vs. 434 +/- 50 vs. 412 +/- 46 cpm, P < 0.0001). Second, the RT activity was not endogenous, because the Con A-stimulated lymphoblastoid cells were obtained from the individuals who were negative for retrovirus. Third, virus-like particles (80-100 nm in diameter) by electron microscopy were found in the concentrated pool supernatants of particulate fraction containing RT activity subjected to sucrose density gradient, obtained from KD patients. Fourth, the viral product, a 31.4 kilodalton molecule, was detected by SDS-PAGE after internal labelling (methionine-S35) and density gradient centrifugation. Fifth, using a "retrovirus universal pol gene region" as a primer and the RT-PCR method, a retrovirus-specific band was detected in the cocultivated supernatants obtained from four KD and one AIDS patients but not in patients with rubella or in healthy controls.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Virus-like particles with reverse transcriptase activity associated with Kawasaki disease. 128 52

It is difficult to evaluate the protective efficacy of species-specific viruses of humans and expensive companion animals where there is no non-human animal model. This study describes an in vivo model system which allows simultaneous operation of humoral, cell-mediated, interferon-like or other unidentified immunological defence mechanisms. There was evidence of in vivo inactivation of both enveloped and unenveloped DNA and RNA viruses including retrovirus mouse sarcoma virus/mouse leukaemia virus as evaluated by assay of the enzyme reverse transcriptase. This model will allow examination of vaccine efficacy in immunocompetent host animals while avoiding morbidity and/or mortality from virus infection in these animals.
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PMID:In vivo model for evaluation of species-specific virus vaccines. 133 88


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