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)

The simultaneous detection test gave no evidence for the presence of RNA tumour viruses in herpesvirus induced malignant lymphomas of non-human primates. The 12 tumours tested were obtained from three different monkey species inoculated with Herpesvirus saimiri or herpesvirus ateles. Particles encapsulating RNA-instructed DNA polymerase and high mol. wt. virus-related RNA were easily demonstrated in tumours of the mouse induced by type-C or type-B oncornaviruses and in human lymphoid cells infected with simian sarcoma virus type I which were examined in parallel. Attempts to demonstrate partial expression of an oncornavirus genome in the herpesvirus induced tumours and attempts to detect an interspecies antigen related to monkey oncornaviruses were negative and strengthened the observations made with the simultaneous detection test.
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PMID:No evidence for particles encapsulating RNA-instructed DNA polymerase and high molecular weight virus-related RNA in herpesvirus induced tumours of non-human primates. 4 97

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

Cell lines obtained by in vitro transformation of bone marrow with Abelson murine leukemia virus (A-MuLV) can be divided into three classes: producers, releasing reverse transcriptase-containing particles and infectious virus; nonproducers, releasing no viral particles; and defective producers, the most common phenotype, releasing particulate reverse transcriptase in the absence of infectious virus. When such cell lines were analyzed 1 to 2 weeks after their isolation, however, all produced infectious virus. Because these cell lines were carried in culture, many ceased to release infectious virus but produced defective virions. One defective producer, SWR4, has been extensively studied. The particles it produces have the same density as that of virions of Moloney murine leukemia virus (M-MuLV). The particles contain no 35 to 70S RNA, as determined by analysis of [3H]uridine-labeled particles, and exhibit no endogenous reverse transcriptase activity. Although the reverse transcriptase enzyme is of normal size, the major structural protein of the defective virions has a molecular weight of 28,000 (p28), in contrast to the p30 of M-MuLV, and no viral glycoprotein was evident. The defective particles do not appear to arise either from the helper virus or from Abelson virus. An alteration of the protein of the helper virus is an unlikely source of p28 because particles produced by lymphoid cells transformed with another strain of M-MuLV as helper (M-MuLV-TB) contained p28 with an unaltered cleavage pattern, although M-MuLV-TB p30 differs from M-MuLV p30. The A-MuLV genome lacks the capacity to code for the reverse transcriptase virions. Clones of fibroblasts infected with A-MuLV only occasionally produce defective particles. The defective particles therefore probably arose from an endogenous virus that is preferentially expressed in the class of lymphoid cells transformed by A-MuLV. This interpretation implies that the majority of A-MuLV-transformed lymphoid cells completely lose expression of the helper virus genome.
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PMID:Virus production by Abelson murine leukemia virus-transformed lymphoid cells. 9 Jan 75

Extracts from lymphoid and fibroblast cell lines transformed by Abelson murine leukemia virus (A-MuLV) contain a protein of molecular weight 120,000 (P120). Immunoprecipitation with specific sera shows that P120 contains regions homologous to the 5'-terminal segment of the MULV gag gene complex--p15, p12, and at least part of p30--but lacks detectable determinants of p10, reverse transcriptase, and the envelope glycoprotein. P120 is phosphorylated and has an intracellular half-life of 3--6 hr. In vitro translation of virion RNA from A-MuLV, with Moloney MuLV as helper, yields a product of molecular weight 120,000 with serological reactivity similar to that of the cellular P120. Translation of the RNA from the helper gave no P120. P120 is expressed in all lymphoid and fibroblastic cell lines we have tested that were transformed by A-MuLV but is not detectable in a lymphoid line in which the A-MuLV genome was established by infection but was not responsible for the transformation. Expression of P120 is selectively retained in clones of A-MuLV-transformed lymphocytes that convert to a nonproducer state after loss of expression of helper MuLV intracellular precursors. These results suggest that the P120 product of the A-MuLV genome may be responsible for maintenance of the transformed phenotype of lymphoid and fibroblast cells transformed by the virus.
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PMID:Identification of an Abelson murine leukemia virus-encoded protein present in transformed fibroblast and lymphoid cells. 20 68

Moloney murine leukemia virus (MoMuLV) grown in 2 lymphoid-derived murine cell lines (JLS-V9 and TB) contained 2 size classes of RNA subunits: 2.8 +/- 0.4 x 10(6) (n = 30) and 1.6 +/- 0.1 x 10(6) (n = 15) daltons. Detectable levels of low molecular weight viral RNA (LMW vRNA) were not present in MoMuLV grown in mouse embryo fibroblasts, nor rat cells, nor was it produced by them when they were infected with MoMuLV containing both species of vRNA. DNA probes complementary to both subunits were synthesized separately using purified reverse transcriptase (R.T.) and calf thymus DNA as primer. Polyadenylated LMW vRNA was selected and, by molecular hybridization was found to be completely homologous with the large RNA subunit. This was confirmed using cDNA probes representing defined regions of the genome. The LMW vRNA therefore contains multiple subsets of the viral RNA, which could correspond to multiple deletion mutants possibly generated by an efficient RNA splicing mechanism. In addition, low levels of non-homologous virus-like RNA were detected in MoMuLV grown in TB (2%) AND NIH/3T3 cells (0.4%).
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PMID:Sub-genomic RNA in Moloney leukemia virus grown in lymphoid-derived cell lines consists primarily of homologous viral RNA. 50 51

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

Cystic fibrosis transmembrane conductance regulator (CFTR) is expressed at low levels in nonepithelial cells. Recently, we demonstrated that CFTR is responsible for cell cycle-dependent adenosine 3',5'-cyclic monophosphate-responsive Cl- permeability in lymphocytes. Agonist responsiveness of cystic fibrosis (CF) lymphocytes was restored by transfection with plasmid containing wild type CFTR cDNA. CFTR mRNA is expressed in the B lymphoid cell line GM03299; however, quantitative reverse transcriptase-polymerase chain reaction indicates that the level of CFTR mRNA is at least 1,000 times lower than in T84 cells. CFTR protein could not be detected by Western blot or by immunoprecipitation of in vitro phosphorylated protein. However, antisense oligonucleotides representing codons 1-12 of CFTR caused a complete inhibition of cell cycle-dependent Cl-permeability [as determined by 6-methoxy-N-(3-sulfopropyl)-quinolinium fluorescence digital-imaging microscopy], thereby inducing normal cells to acquire a "CF phenotype." These studies provide direct evidence that a CFTR-associated Cl- permeability is present and measurable in lymphocytes, even though CFTR mRNA and protein are expressed at low levels.
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PMID:Antisense oligonucleotides to CFTR confer a cystic fibrosis phenotype on B lymphocytes. 128 96

We have previously demonstrated that acidic medium inhibits the replication of HIV-1. The present study was designed to examine the effects of other growth conditions and infection of fibroblasts by coculture with HIV infected lymphoid cells. Several lymphoblastoid cell lines normally grown in RPMI-1640 were grown in Eagle's MEM. These cells supported virus replication to higher titres than did RPMI-1640. Peak viral titres were achieved within 24-48 h after newly infected or chronically infected cells were placed in fresh medium. When virus was stored in liquid medium either frozen or at higher temperatures, virus titres were retained for several months while frozen but decreased upon storage at 4 degrees C or higher. If cells were passaged after trypsinization in Ca(++)-depleted medium, then a decreased susceptibility of cells for HIV-1 by 2 log10 at 24 h post infection was observed. Infectivity of cell-free and cell-associated HIV-1 was measured using syncytium formation, reverse transcriptase activity and p24 antigen. No fusion between HIV-1 infected CD4+ lymphoblasts and CD4- fibroblasts was observed but HIV-1 infected lymphoid cells, even in the absence of syncytium formation, exerted a strong toxic effect on fibroblasts. This study extends previous findings that medium acidity was inhibitory to virus replication and survival. Thus, conditions for study of HIV must be well controlled in buffered medium so that misleading results are not obtained regarding virus multiplication and possibly regarding transmission to and pathogenesis in CD4- cells.
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PMID:The influence of cell culture and storage conditions on HIV-1 infectivity and fusogenic activity. 128 37

To develop the polymerase chain reaction (PCR) for the detection of simian T-lymphotropic virus type I (STLV-I) infection, cell lines or peripheral-blood mononuclear cells (PBMC) from 2 non-human primate species [African green monkeys (AGM), Cercopithecus aethiops; baboon, Papio cynocephalus] were evaluated for their STLV-I status using oligonucleotide primer pairs and probes specific for the tax and pol gene regions of the closely related human T-lymphotropic virus type I (HTLV-I). These PCR results were compared with serologic (Western blot assay) and viral culture (p24-antigen capture assay) data. PCR products for both gene regions were detected in established baboon, Japanese macaque and rhesus macaque STLV-I-producing cell lines. STLV-I tax and pol products were also detected in PBMC from 4 of 4 infected AGM and 4 of 4 infected baboons, each of which were also Western-blot-positive and p24-antigen-capture-positive. Of the remaining AGM (n = 7) and baboon (n = 1) which were PCR-negative, each was also Western-blot-negative and p24-antigen-capture-negative. Two seronegative and virus-culture-negative AGM were classified as PCR indeterminate with weak reactivity using tax primers. These primer pairs failed to amplify DNA from uninfected human PBMC, an uninfected human lymphoid cell line, a simian immunodeficiency virus macaque (SIVmac251)-infected cell line and a simian-retrovirus-type-D(SRV-D)-infected cell line. HTLV-II-pol-specific primer pairs failed to amplify DNA from STLV-I-infected cell lines and PBMC from STLV-I-infected monkeys. Further, HTLV-I pol and tax primer pairs successfully amplified RNA from HTLV-I- and STLV-I-infected cell lines by reverse transcriptase (RT)-PCR. We have demonstrated excellent specificity in the detection of STLV-I by PCR using these HTLV-I-derived primers and probes. Additionally, our data suggest that the tax and pol gene regions are conserved between HTLV-I and STLV-I strains found among these diverse species of non-human primates.
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PMID:Detection of simian T-lymphotropic virus type I using the polymerase chain reaction. 131 66

Immunosuppression suspected to be associated with retrovirus infection was diagnosed in an 18-month-old female llama. The llama had a 6-month history of weight loss, intermittent lameness, and infections that were nonresponsive to treatment. Serial CBC indicated persistent nonregenerative anemia and leukopenia characterized by absolute neutropenia and lymphopenia. Functional hypoplasia of myeloid and erythroid cell lines was detected in serial bone marrow biopsy specimens. Notable pathologic findings included inadequate hematopoiesis, generalized lymphoid hypoplasia and plasma cell depletion, and pulmonary alveolar histiocytosis. Pneumocystis carinii cysts and viral particles of the size and morphologic features consistent with the retrovirus family were observed in lung sections examined by transmission electron microscopy. Antemortem macrophage and postmortem lymph node cultures were positive for reverse transcriptase activity.
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PMID:Apparent retrovirus-induced immunosuppression in a yearling llama. 133 Oct


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