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)

Permanent cell lines have been established from a spleen nodule and lymph node of a male Hodgkin's disease (HD) patient whose father has the same disease. Th in vitro growth pattern morphological and cytogenetic characteristics of these lines maintained continuously for over 2 years are described. The cultures contain a population of mixed cell types that grow in suspension. Between 5 and 10% of the cells have surface immunoglobulins M and D. B-cell alloantigens are also detectable. While the cultures are predominantly lymphoid, some of the large cells, by light and electron microscopy, resemble the Reed-Sternberg and Hodgkin's cells of the original biopsies. Although the cells maintain the human diploid karyotype, they are heterotransplantable in nude mice. After 14 months of culture, chromosome rearrangement and losses, commonly seen in leukemic bone marrow, occurred. Close to 100% of the cells are Epstein-Barr nuclear antigen positive, but they lack Epstein-Barr viral (EBV) capsid antigen and EBV-induced early antigen. Nucleic acid hybridization tests indicated that there were no more than two EBV genome equivalents per cell. Tests with HD sera free of anti-EBV were negative. Electron microscope examination of the cells revealed the presence of intracellular as well as extracellular rare pleomorphic particles ranging from 400 to 1200 A. The nature of these particles, which increased in number after the cultures were treated with halogenated pyrimidines but not with dimethyl sulfoxide, remains questionable. The cultures derived from the mouse-passaged HD cells, however, had reverse transcriptase activity and readily identifiable type C particles which were probably of murine origin. These cultures have some unique features that make them useful in studying the perplexing pathological entity of HD.
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PMID:Observations on cell lines derived from a patient with Hodgkin's disease. 7 64

Permanent cell lines have been established from twelve diffuse histiocytic lymphomas (SU-DHL-1 to -12), three American Burkitt's lymphomas (SU-AmB-1 to -3), two acute lymphoblastic leukemias (SU-ALL-1 and -2), and three diffuse undifferentiated lymphomas (SU-DUL-1, -2, and -3). The cultured cells displayed neoplastic characteristics, as manifested by heterotransplantability in congenitally athymic nude mice and by the presence of cytogenetic abnormalities in early passage generations. Functional and marker studies revealed that the three American Burkitt's lymphomas, as well as several of the diffuse histiocytic and undifferentiated lymphomas, were of B-lymphocytic origin, whereas the two acute lymphoblastic leukemias were both of T-lymphocytic origin. Two of the cell lines, SU-DHL-1 and -2, appeared to be of true histiocytic origin; two others exhibited no markers and were designated as "null" cells. All ten of the DHL cell lines studied to date, as well as SU-DUL-1, have been devoid of Epstein-Barr virus (EBV) genomes by the EBNA test, whereas two of the three American Burkitt's lymphoma cell lines were positive. Spontaneous production of a C-type RNA virus was first detected in post-mitochondrial cytoplasmic fractions and culture fluids of the SU-DHL-1 cell line. Screening assays for the detection of reverse transcriptase-positive particles in the culture fluids of the other cell lines indicate that eight of the fifteen cell lines tested to date have spontaneously initiated C-type RNA virus production. After partial purification by ion-exchange and affinity chromatography, the reverse transcriptases of the virus isolated from SU-DHL-1 cells is partially inhibited by antibodies to the reverse transcriptases of C-type viruses of subhuman primate and endogenous feline, but not of murine, origin. Conversely, antibody prepared against the purified SU-DHL-1 viral reverse transcriptase, at concentrations which maximally inhibit the homologous enzyme, partially inhibits the reverse transcriptases of subhuman primate C-type viruses, but has little or no inhibitory activity against the reverse transcriptases of feline or murine leukemia viruses. The viruses produced by the SU-DHL-1 and SU-AmB-3 cell lines have been shown to be infectious for normal human peripheral blood mononuclear cells, normal human bone marrow cells, and certain human lymphoblastoid cell lines. After infection by these viruses, normal human peripheral blood mononuclear cells and human bone marrow cells have exhibited striking changes in growth behavior and morphology which, though not permanently sustained, have many of the features of abortive transformation.
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PMID:Biology and virology of the human malignant lymphomas: 1st Milford D. Schulz Lecture. 8 2

Lymphoblastoid cell lines were derived from patients with active systemic lupus erythematosus by allowing spontaneous transformation of peripheral B lymphocytes (B cells) harboring endogenous Epstein-Barr virus or by superinfecting peripheral lymphocytes with exogeneous Epstein-Barr virus. Results of extensive studies aimed at identifying type C oncornaviruses in these lymphoblastoid cells were entirely negative by electron microscopy, DNA-DNA hybridization, reverse transcriptase assays, and cocultivation experiments. These results do not support the postulated association of oncornavirus infection in human systemic erythematosus.
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PMID:Search for Epstein-Barr and type C oncornaviruses in systemic lupus erythematosus. 8 43

Conditioned medium from a culture of whole human embryo cells stimulated prolonged exponential growth in suspension culture of leukocytes from a patient with acute myelogenous leukemia. Ten to 20% of the cultured cells consistently differentiated into mature granulocytes including neutrophils, eosinophils, and basophils. The proportion of lymphocytes declined after culturing, and tests for Epstein-Barr virus antigens were negative. An abnormality of a G group chromosome was observed in some metaphases from the patient's fresh bone marrow and from the cultured leukocytes, indicating growth in vitro of leukemic cells. After 4-10 weeks in culture, a budding type-C virus was continuously released by the cultured leukocytes, predominantly by undifferentiated blast cells. This virus was originally identified in three different cultures of a peripheral blood specimen obtained at the time of diagnosis. Subsequently, this virus was identified by reverse transcriptase (RNA-dependent DNA polymerase) assays and by electron microscopy in cultured leukocytes from a bone marrow specimen obtained 14 months later from the same patient. Virus produced by cultures of both specimens was closely related, if not identical, to the woolly monkey type-C virus.
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PMID:Growth and differentiation in culture of leukemic leukocytes from a patient with acute myelogenous leukemia and re-identification of type-C virus. 17 97

We have partially purified and characterized two separate DNA polymerase activities associated with Epstein-Barr virus (EB virus). One activity is present in EB virus producer cell lines but not in nonproducer or negative cell lines. It adheres more strongly to DEAE-cellulose than any host cell enzymes, eluting at 210 to 270 mM potassium phosphate buffer. Further elution from phosphocellulose and sedimentation in glycerol gradients yields an enzyme purified 900-fold with an S value of 8.3. The second DNA polymerase activity co-purifies with EB viral particles, elutes at low salt from DEAE-cellulose (40 to 60 mM potassium phosphate buffer) and phosphocellulose (100 mM), and has an S value of 9.5 on glycerol gradient sedimentation. These two enzymes are referred to for convenience as the EB virus-induced DNA polymerase and the EB virion-associated DNA polymerase. The EB virus-induced polymerase can be distinguished from host alpha, beta, and the virion-associated polymerase in 1) being resistant to salt inhibition, 2) having a more basic pH optima in Tris buffer (pH 9.5), and 3) having a 10-fold lower saturating concentration for the activated DNA template. The EB virion-associated polymerase is distinguished from host alpha, beta, and the EB virus-induced polymerase, because it cannot utilize synthetic deoxy- and ribohomopolymer primer-templates in place of the activated calf thymus DNA template in DNA polymerase assays. Neither of the EB virus-associated polymerases can copy the ribohomopolymers dT10poly(rA) or dG12-18(poly(rC) efficiently and therefore can be distinguished from host gamma polymerase and reverse transcriptase. The activity of the EB virus-induced and virion-associated polymerases are unaffected both by antibody to alpha polymerase, and by antiserum with high antibody titers to EB early antigen and viral capsid antigen.
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PMID:Two Epstein-Barr virus-associated DNA polymerase activities. 21 39

The addition of iododeoxyuridine to P3HR-I cell cultures led to a large increase in both Epstein-Barr virus (EBV)-induced DNA polymerase activity and early antigen-positive cells. This EBV-induced DNA polymerase was separated from the cellular alpha- and beta-polymerases by sequential column chromatography on Sepharose 6B, DEAE-cellulose, and phosphocellulose, resulting in partial purification of about 320-fold. The partially purified-EBV DNA polymerase could be distinguished from the cellular DNA polymerases by its activation by salts, its catalytic properties, and its degree of sensitivity to N-ethylmaleimide, phosphonoacetic acid, araATP, and araCTP. The viral polymerase showed properteis similar to those reported for other herpesvirus DNA polymerases. The enzyme exhibited optimal activity for copying activated calf DNA in the presence of 50 mH (NH4)2SO4 and was resistant to 150 mM (NH4)2SO4. It utilized with high efficiency template-primer poly(dC)-oligo(dG)12-18 or poly(dA)-oligo(dT)12-18, but failed to copy poly(rA)-oligo(dT)10 and oligo(dT)10, indicating that this enzyme has characters distinct from DNA polymerase gamma, reverse transcriptase, and terminal deoxynucleotidyl transferase. Phosphonacetic acid inhibited not only EBV DNA polymerase, but also, to a lesser degree, the cellular polymerase alpha. AraATP did not severely inhibit viral activity, whereas the polymerase alpha was inhibited most effectively. Both EBV polymerase and polymerase alpha were inhibited at a comparable level by araCTP.
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PMID:Characterization of an Epstein-Barr virus-induced DNA polymerase. 21 9

Velocity sedimentation of uridine-labelled cultures was found to be more reliable than isopycnic sedimentation in detecting oncornavirus production in lymphoid cells. Of 13 cell lines (including six derivea from Burkitt's lymphomas and two from leukaemic leukocytes) only one, the leukaemia-derived, Epstein-Barr virus-producing line QIMR-WIL, showed any activity. The nature of the QIMR-WIL particles was further defined by isolation of uridine-labelled 70S RNA and by the simultaneous assay for reverse transcriptase and 70S RNA, but production of such particles was detected in only three of 10 assays. Pretreatment of cells with 5'-iododeoxyuridine or culture in arginine-free medium did not induce particle production. Syncytia assays using XC cells were negative. Of 13 primary cultures (nine samples of leukaemic leukocytes and four of cord leukocytes) treated with mitogens and subjected to inducing conditions, one (leukocytes from a patient with acute myelogenous leukaemia) showed evidence in successive assays of oncornavirus synthesis. The low and transient yield of oncornavirus-like particles obtained in this work parallels that reported in previous studies of fresh lymphoid cells and primary cultures.
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PMID:Survey of human lymphoblastoid cell lines and primary cultures of normal and leukaemic leukocytes for oncornavirus production. 97 88

Down-regulation of Epstein-Barr virus (EBV) induced transformation of human lymphocytes in vitro by dehydroepiandrosterone (DHEA), a naturally occurring human steroid secreted by the adrenal gland has been demonstrated. This article reports on the effects of DHEA and its novel synthetic analogs 16 alpha-fluoro-5-androsten-17-one (8354) and 3 beta-hydroxy-16 alpha-fluoro-5 alpha-androstan-17-one (OH8356) on human immunodeficiency virus (HIV-1) replication. Treatment with DHEA, 8354, or OH8356 resulted in a modest down-regulation of HIV-1 replication in phytohemagglutinin-stimulated peripheral blood lymphocytes as measured by syncytia formation, release of p24 antigen, and accumulation of reverse transcriptase activity. DHEA and 8354 also reduced syncytia formation in HIV-1-infected SupT1 lymphoblasts. DHEA and synthetic analogs of DHEA, which have been shown previously to have antiproliferative effects, now are shown to reduce HIV-1 replication. DHEA or synthetic analogs of DHEA could provide an alternative and/or adjuvant for HIV-1 infection.
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PMID:Dehydroepiandrosterone (DHEA) and synthetic DHEA analogs are modest inhibitors of HIV-1 IIIB replication. 138 Dec 6

The Epstein-Barr virus (EBV) has been increasingly detected in Hodgkin's disease (HD), but its role in pathogenesis remains uncertain. We analyzed 20 specimens of HD known to contain EBV DNA by a sensitive reverse transcriptase polymerase chain reaction (RT-PCR). The cases were assessed for the presence of RNA transcripts of the BNLF1 gene (coding for the viral latent membrane protein [LMP]) and the late replicative gene BLLF1 (coding for the principle envelope glycoprotein [gp220/350]). LMP RNA transcripts were found in 9 of 20 (45%) cases, mostly those containing many copies of viral DNA and of mixed cellularity (MC) histological subtype. Only one LMP RNA-positive case was also positive for RNA transcripts of the active replication gene BLLF1. Our results show that viral burden in HD is not primarily related to active viral replication, but is associated with LMP gene expression.
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PMID:Epstein-Barr virus burden in Hodgkin's disease is related to latent membrane protein gene expression but not to active viral replication. 138 93

T-cell-mediated cytotoxicity may play an important role in control of infection by the human immunodeficiency virus (HIV). In this study, we have identified and characterized a relatively conserved epitope in the HIV-1 reverse transcriptase recognized by murine and human cytotoxic T cells. This epitope was identified using a murine antigen-specific CD8+ class I major histocompatibility complex-restricted cytotoxic T-cell (CTL) line, a transfected fibroblast cell line expressing the HIV-1 pol gene, recombinant vaccinia viruses containing different truncated versions of the pol gene, and overlapping synthetic peptides. The optimal antigenic site was identified as residues 203-219 by synthesizing extended or truncated peptide analogs of the antigenic fragment. The optimal peptide was then tested for sensitization of autologous Epstein-Barr virus-transformed B-cell targets for killing by fresh human peripheral blood mononuclear cells. It was recognized by CTLs from several HIV-seropositive patients but not from any seronegative donor. Therefore, this peptide is a good candidate for inclusion in an AIDS vaccine. This study demonstrates that the same CTL epitope can be seen by murine and human CD8+ CTLs, as previously demonstrated for epitopes recognized by CD4+ helper T cells, and suggests the utility of screening for immunodominant CTL epitopes in mice prior to carrying out studies in humans.
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PMID:An epitope in human immunodeficiency virus 1 reverse transcriptase recognized by both mouse and human cytotoxic T lymphocytes. 169 Apr 29


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