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 capacity of interferon to inhibit virus production in cells chronically infected with oncornavirus enabled us to develop a simple system for interferon quantitation that was independent of exogenous viral infection. The release of the virus to the culture medium was determined by its reverse transcriptase activity. The inhibitory effect of interferon in this system was linearly proportional to the log of its dilution over a range between 5 and 80% inhibiton. The sensitivity of the system was comparable to that of the vexicular stomatitis virus plaque reduction assay, whereas its reproducibility was found to be even better. This method is very rapid and can be completed within less than 24 h.
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PMID:Rapid quantitation of interferon with chronically oncornavirus-producing cells. 6 Nov 74

Clones of cells were isolated from single virus-single cell infections of NIH/3T3 cells with Moloney murine leukemia virus. Approximately one third of such clones aberrantly expressed viral gene functions. One clone produced virus with altered plaque morphology, while others failed to produce particles able to make plaques on XC cells. In addition, clones that made particles lacking reverse transcriptase were found, and these did not synthesize the reverse transcriptase precursor Pr180 gag-pol. One clone (M23) lacked any detectable glycoprotein or reverse transcriptase. Despite these defects, each clone released particles of type C morphology, suggesting that gag gene function alone may be sufficient for particle production. All the particles contained viral RNA of 60-70S that was composed of the normal 35S size subunits except for M23, which had a deletion in the viral genome of approximately 1000-1500 nucleotides. A variety of defective clones were also isolated following infection of rat cells with Moloney virus. It is apparent that the murine leukemia virus genome is ofter mutated by spontaneous processes generating a wide range of phenotypes.
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PMID:High frequency of aberrant expression of Moloney murine leukemia virus in clonal infections. 8 Feb 81

A nonconditional mutant of B-tropic murine leukemia virus (MuLV), defective in polymerase, has been isolated by cloning chronically infected cells. The cell clone containing the mutant produced virus particles which were noninfectious. However, superinfection of the cells by replication-competent XC-negative viruses resulted in the rescue of virus capable of forming plaques in a modified XC test, termed the "complementation plaque assay" (A. Rein and R. H. Bassin, J. Virol. 28:656-660, 1978). Analysis of the noninfectious virions produced without superinfection demonstrated that they contained only 2 to 5% of the wild-type level of reverse transcriptase activity. Purification of this activity indicated that it was associated with a smaller molecule than that produced by wild-type virus. Cells producing the mutant virions did not contain the gag-pol precursor, Pr180gag-pol; however the cells contained proteins of 147K and 114K daltons precipitable with anti-pol serum. All of the normal structural proteins as well as 70S genomic RNA could be detected in the mutant particles. An interference test indicated that a functional ecotropic glycoprotein was synthesized by the mutant. These results indicate that the mutant has a unique defect in the pol gene.
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PMID:Mutant of B-tropic murine leukemia virus synthesizing an altered polymerase molecule. 9 71

Murine teratocarcinoma stem cells are nonpermissive for productive infection by a variety of DNA (polyoma and SV40 virus) and RNA (murine leukemia and sarcoma virus) tumor viruses whereas differentiated murine cells derived from the stem cells are permissive for productive (or abortive in the case of SV40) infection by these same viruses. The block to productive infection by these oncogenic viruses is at a postpenetration step in the replication cycle of these viruses but the precise level of the block has not been established for any of these viruses. In this report we describe teratocarcinoma-derived stem and differentiated cell lines which should be especially useful in determining the level of the block to replication of ecotropic murine leukemia virus in murine teratocarcinoma stem cells. The stem cell line, OTT6050AF1 BrdU, which is completely nonpermissive to productive infection by Moloney murine leukemia virus and consists of 97% pluripotent stem cells, contains DNA copies of an RNA tumor virus which is indistinguishable from the N-tropic murine leukemia virus of AKR mice. The stem cells are negative for expression of viral reverse transcriptase, p30 and gp69/71 and no virus is found by XC plaque assay or other biological tests. Differentiated cells established from the same teratocarcinoma tumor are 100% positive for viral gp69/71, p30, and produce large amounts of reverse transcriptase activity and N-tropic virus as detected by biological assay. The virus isolated from the differentiated cells is closely related, if not identical to AKR N-tropic virus by nucleic acid hybridization studies and is thus not an endogenous virus of the 129 strain of mice. The teratocarcinoma tumor from which the cell lines were established had been carried in 129 mice and perhaps at some time in the mouse passage history the tumors were infected (nonproductively) with the N-tropic virus. Regardless of the origin of this viral DNA, the OTT6050A derived stem and differentiated cell lines should be extremely useful in defining in stem cells the step at which ecotropic murine leukemia virus replication is blocked.
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PMID:A murine teratocarcinoma stem cell line carries suppressed oncogenic virus genomes. 45 80

The nucleotide analogue digoxigenin-11-dUTP is widely used as a nonradioactive marker in a broad range of techniques including dot blots, Southern and Northern blots, colony and plaque screenings and in situ hybridizations. In this report, we describe the incorporation of this molecule into a cDNA synthesized by reverse transcriptase as a novel application for digoxigenin. This reaction can be performed as a useful control to check the integrity of a bulk mRNA preparation in the construction of a cDNA library, since the ability of mRNA to direct the synthesis of long molecules of first-strand cDNA is a sign of its integrity.
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PMID:Synthesis of digoxigenin-labeled cDNA as a test for mRNA integrity. 128 46

To investigate whether human immunodeficiency virus type 1 pol gene mutations are selected during prolonged 2',3'-dideoxycytidine (ddC) therapy, we used the polymerase chain reaction to amplify a portion of the reverse transcriptase segment of the pol gene from the peripheral blood mononuclear cell DNA of a patient with AIDS before and after an 80-week course of ddC therapy. The consensus sequence from the second sample contained a unique double mutation (ACT to GAT) in the codon for reverse transcriptase amino acid 69, causing substitution of aspartic acid (Asp) for the wild-type threonine (Thr). A mutation (ACA to ATA) also occurred in the codon for position 165, causing substitution of isoleucine (Ile) for Thr. The GAT (Asp) codon was introduced into the pol gene of a molecular clone of human immunodeficiency virus via site-directed mutagenesis. Following transfection, mutant and wild-type viruses were tested for susceptibility to ddC by a plaque reduction assay. The mutant virus was fivefold less susceptible to ddC than the wild type; cross-resistance to 3'-azido-3'-deoxythymidine or 2'3'-dideoxyinosine was not found. The Ile-165 mutation did not confer additional ddC resistance. The Asp-69 substitution may have contributed to the generation of resistant virus in this patient.
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PMID:Human immunodeficiency virus type 1 pol gene mutations which cause decreased susceptibility to 2',3'-dideoxycytidine. 131 43

RNA of more than 40 hantavirus isolates, originating from rodents and humans of widely separated geographical areas, was copied to cDNA using reverse transcriptase and amplified by polymerase chain reaction (PCR). A genus-reactive oligonucleotide primer pair, flanking a 365 bp region of the G2 glycoprotein gene, was chosen for genus-reactive PCR. DNA products were digested with 20 restriction endonucleases and cleavage patterns were analysed. For strains of known sequence, the restriction patterns observed were consistent with those predicted from sequence data, demonstrating that the amplified products originated from target virus RNA. Further analyses suggested that all amplified viruses could be easily typed into one of five restriction patterns using only five enzymes. The categories identified by restriction analysis of PCR-amplified cDNA corresponded with serogroups established by plaque-reduction neutralization tests. This method may greatly simplify the identification of new hantavirus isolates.
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PMID:Comparison of hantavirus isolates using a genus-reactive primer pair polymerase chain reaction. 134 58

The order of appearance in the reverse transcriptase gene of four mutations implicated in the development of resistance to zidovudine was investigated by selective polymerase chain reaction. Serial human immunodeficiency virus isolates were studied from 18 initially asymptomatic individuals who had been treated with zidovudine for 2 years. Most subjects had similar patterns. The first mutation occurred transiently at codon 70; its disappearance was paralleled by the appearance of a mutation at codon 215. Subsequently, in some individuals, the mutation at codon 70 reappeared. During the 2 years of treatment, no mutations developed at codon 219 and only one at codon 67, suggesting that most individuals developed only partly resistant virus. This was confirmed by plaque-reduction assay. Six subjects progressed to AIDS within the 2-year study period, confirming that the development of highly resistant isolates is not required for progression in treated individuals. No clear temporal relationship was found between the development of partial resistance and progression.
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PMID:Ordered appearance of zidovudine resistance mutations during treatment of 18 human immunodeficiency virus-positive subjects. 137 Jan 74

A new class of membrane-active ether lipid (EL) analogs of platelet-activating factor were studied for in vitro anti-HIV-1 activity. Human T-cell (CEM-ss) monolayers or suspension cultures were used to determine effects of structural modifications of Type A phosphorus-containing and Type B nonphosphorus EL analogs on (a) the inhibitory concentration50 (IC50) for HIV-1 syncytial plaque formation and cell growth, and, (b) virus budding at the cell plasma membrane. Results indicate that representative Type A and Type B EL inhibit HIV-1 but not herpes simplex virus type 2 plaque formation when added before or up to 2 days after viral infection. Anti-HIV-1 activity does not involve direct inactivation of virus infectivity. Type A EL (IC50 range = 0.2-1.4 microM) with alkyoxy, alkylthio, or alkyamido substitution at glycerol position 1 and ethoxy or methoxy substitution at position 2, and Type B compounds (IC50 range = 0.33-0.63 microM) with an inverse choline or nitrogen heterocyclic substitution at position 3 have selective activity against HIV-1-infected T-cells. EL treatment of HIV-1-infected cells is associated with subsequent release of reverse transcriptase activity, but infectious virus production is inhibited with time after infection. Electron microscopic examination of HIV-1-infected and EL-treated cells revealed absence of detectable budding virus at the plasma membrane but presence of intracytoplasmic vacuolar virus particles. In summary, these data suggest that EL analogs are a novel class of agents that induce defective intracytoplasmic vacuolar HIV-1 formation in T-cells. Being membrane interactive, EL are ideally suited for combination chemotherapy with DNA-interactive anti-HIV nucleoside analogs.
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PMID:Novel membrane-interactive ether lipid analogs that inhibit infectious HIV-1 production and induce defective virus formation. 169 29

A series of dipyridodiazepinones have been shown to be potent inhibitors of human immunodeficiency virus type 1 (HIV-1) reverse transcriptase. The lead compound, BI-RG-587, had a 50% inhibitory concentration of 84 nM against HIV-1 reverse transcriptase activity. This compound reduced plaque formation of HIV-1 in HeLa cells expressing the CD4 receptor by 50% at 15 nM. BI-RG-587 at comparable concentrations inhibited the production of p24 antigen following the acute infection of CEM T-lymphoblastoid cells or primary human monocyte-derived macrophages with HIV-1. No inhibitory effects against HIV-2 or against three picornaviruses were detected. Zidovudine (3'-azido-3'-deoxythymidine [AZT])-susceptible and AZT-resistant isolates of HIV-1 were equally susceptible to BI-RG-587. AZT and BI-RG-587 exhibited synergistic inhibition of HIV-1BRU at all concentrations examined.
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PMID:BI-RG-587 is active against zidovudine-resistant human immunodeficiency virus type 1 and synergistic with zidovudine. 170 76


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