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

---

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

A micromethod for assaying the reverse transcriptase enzyme of human T-cell lymphotropic virus type III/lymphadenopathy-associated virus in cocultures of clinical specimens for viral isolation was developed and compared with the macromethod in use. Ultracentrifuged, pelleted, and solubilized viral culture supernatants were transferred into either tubes (macromethod) or microtiter plates (micromethod) and incubated with tritiated enzyme substrate. Trichloroacetic acid-precipitated DNA was collected on individual filter papers with a Millipore filtration manifold (macromethod) or on filter sheets using a semiautomated cell harvester (micromethod). Filters were then placed in scintillation fluid and counted on a beta scintillation counter. Results of the micromethod significantly correlated to those of the macromethod, with a linear relationship between the two. The cutoffs for positivity based on the mean + 2 standard deviations for a set of known negative specimens (n = 19) was 4,973 cpm for the micromethod compared with 5,336 for the macromethod. The intrarun and interrun variations were comparable for both methods. There was a 67% increase in the maximal daily number of specimens which could be run (100 versus 60) as well as a reduction in reagent use. In summary, the micromethod utilizing a semiautomated cell harvester is comparable to the existing macromethod in accuracy and is an improvement due to savings in time and reagents.
...
PMID:Micromethod for assaying reverse transcriptase of human T-cell lymphotropic virus type III/lymphadenopathy-associated virus. 243 84

Suramin is a potent inhibitor of the reverse transcriptase (RNA-directed DNA polymerase) of retroviruses, including the HTLV-III/LAV (human T-cell lymphotropic virus type III/lymphadenopathy-associated virus) reverse transcriptase. Although suramin is far from specific as a reverse transcriptase inhibitor and known to interact with a multitude of proteins and enzymes, it is able to suppress the replication and cytopathic effect of HTLV-III/LAV at concentrations which are nontoxic for the host cells and readily attainable in humans. Consequently, suramin is also able to block HTLV-III/LAV replication in patients. The mechanism of action of suramin at the molecular biological level, its mode of transport and accumulation by the infected host cells, and the bases for its rather selective virustatic activity remain, to a large extent, to be elucidated.
...
PMID:Suramin in the treatment of AIDS: mechanism of action. 243 36

Human T cell lymphotropic virus type III (HTLV-III)/lymphadenopathy-associated virus is the etiologic agent of the acquired immune deficiency syndrome (AIDS) and AIDS-related complex. The effect of 3'-azido-3'-deoxythymidine (AZT) on the HTLV-III/lymphadenopathy-associated virus infection was quantitatively studied with HTLV type I-carrying MT-4 cells. The AZT compound inhibited HTLV-III-induced cytopathic effect and virus-specific antigen expression in MT-4 cells at concentrations of 5 and 10 microM. In addition, a plaque-forming assay was performed to assess the effect of AZT on virus replication in MT-4 cells freshly infected with HTLV-III and in continuous HTLV-III-producing Molt-4/HTLV-III cells. Results showed that AZT efficiently and effectively inhibited the replication of HTLV-III in infected MT-4 cells. AZT is a strong inhibitor of reverse transcriptase activity of HTLV-III as a triphosphate, to such a degree that even 1.0 pM azido-TTP inhibits 50% of reverse transcriptase activity. However, it did not show any effect in the HTLV-III-producing cell line Molt-4/HTLV-III. Thus, AZT has no effect on virus replication of an already integrated virus. When 5 microM AZT was added to HTLV-III-infected MT-4 within 20 h after infection, a striking suppressive effect was noticed. This concentration was much lower than that which inhibits the growth of MT-4 cells. These results confirm those found in a previous report (H. Mitsuya, K. J. Weinhold, P. S. Furman, H. S. Clair, S. N. Lehrman, R. C. Gallo, D. Bolognesi, D. W. Barry, and S. Broder, Proc. Natl. Acad. Sci. USA 82:7096-7100, 1985) and suggest that AZT might be used as an experimental antiviral agent for AIDS and AIDS-related complex.
...
PMID:Inhibition of replication and cytopathic effect of human T cell lymphotropic virus type III/lymphadenopathy-associated virus by 3'-azido-3'-deoxythymidine in vitro. 243 24

Avarol and avarone are two antimitotic and antimutagenic agents that preferentially inhibit proliferation of T-cell leukemia lines in vitro. This report shows that these compounds have a dose-dependent inhibitory effect on the replication of the etiologic agent of acquired immune deficiency syndrome (AIDS), human T-lymphotropic retrovirus (HTLV-III)/lymphadenopathy-associated virus, in human H9 cells in vitro. Both compounds show a significant cytoprotective effect on HTLV-IIIB-infected H9 cells at concentrations as low as 0.1 microgram/ml (0.3 microM). Both avarone and avarol block in a dose-dependent manner the expression of the p24 and p17 gag proteins of HTLV-III in H9 cells after virus infection and block viral replication, as judged by approximately 80% inhibition of reverse transcriptase activity. These results strongly suggest that these compounds may prove to be useful in the treatment of patients with AIDS and AIDS-related complex.
...
PMID:Inhibition of replication of the etiologic agent of acquired immune deficiency syndrome (human T-lymphotropic retrovirus/lymphadenopathy-associated virus) by avarol and avarone. 243 42

We report that 2',3'-dideoxyadenosine and 2',3'-dideoxycytidine inhibit retroviral DNA synthesis and mRNA expression in T cells exposed to the virus that causes acquired immunodeficiency syndrome, and afford such cells long-term protection in vitro under conditions of substantial viral excess. Both 2',3'-dideoxyadenosine and 2',3'-dideoxycytidine appear to completely block reverse transcription from viral RNA to viral DNA. Viral mRNA expression is also not detected in cells protected by the drugs throughout 30 days of culture following exposure to the virus. Purine and pyrimidine analogues as 2',3'-dideoxynucleoside-5'-triphosphate serve as substrates for the human T-lymphotropic virus type III/lymphadenopathy-associated virus reverse transcriptase to elongate a DNA chain by one residue, after which the chain is terminated. Cloned normal helper/inducer T cells exposed to a cytopathic dose of the virus, but protected by the drugs, respond normally to specific antigen in vitro. These results suggest that the drugs could be promising agents for further studies in the experimental treatment of patients infected with retroviruses.
...
PMID:Long-term inhibition of human T-lymphotropic virus type III/lymphadenopathy-associated virus (human immunodeficiency virus) DNA synthesis and RNA expression in T cells protected by 2',3'-dideoxynucleosides in vitro. 243 23

Immunoglobulin isolated from sera of homosexual men infected with human immunodeficiency virus (HIV) inhibited the reverse transcriptase (RT) activity of HIV. The inhibitory activity was specifically directed against HIV RT, and not against other mammalian retrovirus RT, including human T-lymphotropic virus type I. The relative titer of anti-RT antibody was significantly higher in asymptomatic men than in patients with lymphadenopathy or acquired immune deficiency syndrome (AIDS)-related complex. There was no correlation between the relative titer of anti-RT antibody and the relative titers of antibodies to major virion structural protein as determined by the enzyme-linked immunosorbent assay (ELISA) technique. These data suggest that antibodies to HIV RT may be related to the clinical status and possibly to the different degree of HIV replication in HIV-infected homosexual men.
...
PMID:Immunogenicity of human immunodeficiency virus (HIV) reverse transcriptase: detection of high levels of antibodies to HIV reverse transcriptase in sera of homosexual men. 243 30

The reverse transcriptase polymerase of the human T-cell lymphotropic virus/lymphadenopathy-associated virus has been cloned into an expression vector and expressed in Escherichia coli. Two polypeptides of 66 and 51 kDa molecular mass are detectable in polymerase-expressing bacterial lysates with human patient sera. They are processed from a short-lived 120-kDa polyprotein precursor equivalent to a region consisting of polymerase, protease, and endonuclease. The 51 kDa protein appears to originate from the 66-kDa molecule; additional processing products are 32- and 15-kDa proteins. The bacterially expressed polymerase is enzymatically active and exhibits the template specificities, ion requirements, and response to inhibitors of the authentic enzyme. It was purified by DEAE-cellulose-, phosphocellulose-, and poly(rC)-agarose column chromatography followed by glycerol density gradient centrifugation. It copurifies with an RNase H activity, suggesting the existence of a virus-coded DNA polymerase-RNase H complex. The purified bacterial enzyme allows a safe large-scale screening for inhibitors of both activities.
...
PMID:RNase H activity associated with bacterially expressed reverse transcriptase of human T-cell lymphotropic virus III/lymphadenopathy-associated virus. 244 62

Ribavirin was administered orally in escalating doses for 2 or 4 weeks to 15 symptom-free, human immunodeficiency virus seropositive homosexual men with generalized lymphadenopathy. Reverse transcriptase activity was inhibited during therapy when steady-state plasma concentrations were greater than 6 mumol/L. These concentrations were achieved with 1200 or 2400 mg/day for 2 weeks or a loading dose of 2400 mg/day for 3 days followed by 600 mg/day for 4 weeks. Drug accumulation occurred at all doses. The elimination half-life appeared to be approximately 2 weeks. Reversible adverse reactions, principally resulting in central nervous system symptoms and anemia, correlated with dose and duration of therapy. Immunologic enhancement of T-lymphocyte-mediated mitogen-induced responses was observed in the majority of patients who had reduction in reverse transcriptase activity. However, specific T4+ lymphocyte-mediated antigen-induced responses increased to within the normal range in only three patients. Significant enhancement appeared to correlate with the severity of baseline antigen-induced functional impairment. These data indicate that oral ribavirin can be given for at least 1 month with acceptable toxicity at doses that appear to inhibit human immunodeficiency virus replication.
...
PMID:Ribavirin pharmacodynamics in high-risk patients for acquired immunodeficiency syndrome. 244 79

The new antiviral agent, azidothymidine (AZT; BW A509U), is currently the only successful drug in use for patients with acquired immunodeficiency syndrome. The effect of this thymidine analog, 3'-azido-3'-deoxythymidine, on the replication of the lymphadenopathy-associated virus strain of the human immunodeficiency virus was evaluated by using susceptible H9 and Jurkat cells. Cells were pretreated with concentrations of drug ranging from 0.5 to 100 microM, infected, and maintained in medium containing drug. Virus production was assayed by reverse transcriptase assays, and virus-specific DNA was analyzed by Southern blots probed with cloned human immunodeficiency virus sequences. At 4 to 8 days postinfection, infected cells without drug reached a peak of reverse transcriptase activity that was sustained. Increasing concentrations of AZT caused increasing delays in virus production; however, replicate cultures at nontoxic levels of the drug (up to 25 microM) eventually produced as much virus as did non-drug-treated infected cells, despite the continued presence of the drug. Levels of intracellular, unintegrated, virus-specific DNA paralleled reverse transcriptase levels. Virus-caused cytopathic effect was likewise delayed in drug-treated cultures. Virus recovered from H9 cultures after 25 microM AZT treatment did not appear resistant to AZT.
...
PMID:Resumption of virus production after human immunodeficiency virus infection of T lymphocytes in the presence of azidothymidine. 244 6

We compared an antigen capture assay (Abbott Laboratories, North Chicago, Ill.) with a reverse transcriptase assay to identify and quantify human immunodeficiency virus (HIV) in culture. In direct comparisons of serial dilutions of lymphadenopathy-associated virus type 1, the antigen assay was 100-fold more sensitive than the reverse transcriptase assay in detecting the virus. The antigen assay reacted strongly with 60 different HIV isolates but did not cross-react with human T-cell lymphotropic virus type I, human T-cell lymphotropic virus type II, cytomegalovirus, varicella-zoster virus, herpes simplex virus type 1, Epstein-Barr virus, adenovirus type 5, or poliovirus type 1 or with extracts from four different control human cell lines and eight different phytohemagglutinin-stimulated normal human lymphocytes. Peripheral blood lymphocyte samples from 50 individuals were evaluated by both the antigen assay and the reverse transcriptase assay. The cells from the 34 seropositive individuals were all positive by the antigen assay (range, 3 to 9 days; average time, 5.9 days) and the reverse transcriptase assay (range, 7 to 16 days; average time, 9.6 days). Cells from the 16 seronegative individuals were negative by both assays. These results indicate that the antigen assay is an important addition to the monitoring of HIV production in the lymphocytes of infected patients.
...
PMID:Comparison of antigen assay and reverse transcriptase assay for detecting human immunodeficiency virus in culture. 244 34


<< Previous 1 2 3 4 5 6 7 Next >>

---