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)

Detection of replicating human retroviruses has relied upon rather cumbersome reverse transcriptase, immunofluorescence, or electron microscopic assays. We describe a new sandwich enzyme-linked immunoassay (ELISA) for detecting the human retrovirus, lymphadenopathy-associated virus (LAV), in supernates of LAV-infected human lymphocyte cultures. This LAV capture immunoassay compares favorably with the reverse transcriptase assay, despite the fact that it is performed on 20-fold less supernate material. Because the assay can be performed on 0.1 ml of culture supernate and is done by an ELISA method, LAV inoculation of lymphocyte cultures can be monitored quite conveniently, and endpoint titrations of infectious virus (ID-50 assays) can be performed. We demonstrate the application of the capture assay and ID-50 assay to disinfectant and serum neutralization experiments.
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PMID:Immunoassay for the detection and quantitation of infectious human retrovirus, lymphadenopathy-associated virus (LAV). 298 31

The type C retrovirus simian T-lymphotropic virus type III (STLV-III) has been isolated recently from immunodeficient macaque monkeys at the New England Regional Primate Research Center. The present studies were done to define the in vitro growth characteristics of this agent. STLV-III replicates efficiently in interleukin 2-dependent T-cell cultures of macaque peripheral blood lymphocytes (PBL), less efficiently in such cultures of human and gibbon PBL, and inefficiently in baboon PBL. No replication, as assessed by measuring reverse transcriptase activity in these culture supernatants, could be detected in similarly maintained cultures of chimpanzee, squirrel monkey, and cotton-top tamarin PBL. Like the human acquired immunodeficiency syndrome (AIDS) virus, human T-cell lymphotropic virus III/lymphadenopathy-associated virus (HTLV-III/LAV), STLV-III replicates in T4+ but not T8+ lymphocytes and its infection of macaque and human lymphocytes can be blocked with monoclonal anti-T4 antibodies. STLV-III differs from the human AIDS virus, however, in its apparent inability to grow in the Epstein-Barr virus-transformed B lymphocytes tested, the differing range of nonhuman primate T-cell populations that support its growth, and its less striking toxicity for T lymphocytes. These studies provide further characterization of an agent that will be extremely important in facilitating the development of vaccines and antiviral therapy for AIDS.
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PMID:In vitro growth characteristics of simian T-lymphotropic virus type III. 299 2

Three human T-lymphotropic viruses have been isolated and characterized in the past 5 years. The ability to culture target cells with T-cell growth factor and sensitive detection systems for the virally encoded polymerase reverse transcriptase permitted isolation of HTLV-I, which is strongly linked to the cause of adult T-cell leukemia and associated with other lymphoid malignancies in endemic areas. The same techniques, using a permissive human tumor cell line, allowed the isolation and characterization of HTLV-III/lymphadenopathy-associated virus, which is implicated as the primary cause of the acquired immunodeficiency syndrome (AIDS). This virus shares some features with HTLV-I and HTLV-II, such as additional genes not found in most retroviruses. One gene codes for a transcriptional activator protein and may be a feature of a larger group of related retroviruses. The clear identification of the primary cause of AIDS has resulted in the development of specific immunologic reagents, preventive and therapeutic proposals, and comprehensive identification of the clinical diseases associated with this virus.
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PMID:A human T-lymphotropic retrovirus (HTLV-III) as the cause of the acquired immunodeficiency syndrome. 299 99

A murine monoclonal antibody (MAb), named C.V.K., was produced after immunization with highly purified and sonicated lymphadenopathy-associated virus (LAV). No monoclonal antibody was observed with intact virus used as immunogen. C.V.K. MAb recognizes an epitope present on the precursor gag protein of 55 kilodaltons. Western blot analysis and pulse-chase experiments support the interpretation that after p55 cleavage into p25, p18, and p13, only p18 expresses this epitope. C.V.K. MAb selectively stained only LAV-infected lymphocytes. This intracytoplasmic staining appears 3 days after the infection and is correlated with reverse transcriptase activity. Neither membrane immunofluorescence of infected lymphocytes nor neutralizing activity was observed with C.V.K. MAb. These facts suggest that p55 and p18 are not expressed at the cell membrane or on the viral envelope. C.V.K. MAb should prove useful not only in the purification of core proteins but also for detecting infected cells producing the virus in suspension or on histologic sections.
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PMID:A monoclonal antibody against LAV gag precursor: use for viral protein analysis and antigenic expression in infected cells. 300 97

Aurintricarboxylic acid, an anionic triphenylmethane dye, and Evans Blue, an anionic compound structurally related to suramin, are, like suramin itself, inhibitors of human T-cell lymphotropic virus type III (HTLV-III)/-lymphadenopathy-associated virus (LAV) in vitro. These compounds may be targeted, at least in part, at the HTLV-III/LAV reverse transcriptase. The lack of any appreciable cytostatic action of aurintricarboxylic acid, Evans Blue and suramin against several murine and human cell lines, their inability to inhibit cellular DNA, RNA and protein synthesis, and their high lethal dose-50 (greater than or equal to 0.340 g/kg) for NMRI mice point to the selectivity of the compounds as inhibitors of HTLV-III/LAV.
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PMID:Aurintricarboxylic acid and Evans Blue represent two different classes of anionic compounds which selectively inhibit the cytopathogenicity of human T-cell lymphotropic virus type III/lymphadenopathy-associated virus. 301 Sep 77

We explored the possibility that normal human monocytes can be infected with the retrovirus human T lymphotropic virus type III/lymphadenopathy-associated virus (HTLV-III/LAV). The T4 antigen, believed to be the receptor for HTLV-III/LAV binding to CD4 cells, is found on monocytes at low levels. Anti-T4A, which recognizes an epitope on the T4 molecule, inhibits viral binding to monocytes, and virus inhibits anti-T4A binding, although inhibition in both cases is not total. Virus particles were detected in HTLV-III/LAV-pulsed monocytes by electron microscopy as early as 10 min and for up to 3 days after inoculation, although budding virus was not observed. Monocytes were exposed to virus, were washed, and were cultured. Monocyte cultures were monitored by conventional assays for virus replication: immunofluorescence detection of cytoplasmic virus, supernatant reverse transcriptase activity, and supernatant virus antigen. These assays were either negative or at the lower limits of positivity. However, the amount of infectious virus was shown to increase over time in monocyte cultures by harvesting monocytes or their culture supernatants and titrating them into assay cultures containing stimulated T cells. Virus recovery from monocytes and virus recovery from T cells differed both quantitatively and qualitatively. Recovery from T cells and T cell supernatants peaked at 3 to 6 days and declined thereafter. Recovery from monocytes and monocyte supernatants increased over time in culture and never attained the levels of T cell cultures. Taken together, these studies indicate that HTLV-III/LAV binds to monocytes via the T4 molecule and enters the cells. Infectious virus is retained and increases with time in infected monocyte cultures. Both viral binding and infection are at low levels compared with levels in T cells. Unlike the usual infection of T cells characterized by high level virus replication with cell depletion, the infection appears to be persistent in monocytes.
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PMID:In vitro infection of human monocytes with human T lymphotropic virus type III/lymphadenopathy-associated virus (HTLV-III/LAV). 301 9

The retroviruses human T-cell lymphotrophic virus-I (HTLV-I) and HTLV-III/LAV (lymphadenopathy-associated virus) are clearly linked to human diseases. Patients with HTLV-I-positive neoplasms may respond transiently to traditional chemotherapy, but are not cured. For patients with acquired immune deficiency syndrome (AIDS) there is no curative therapy. In retroviruses of different species, viral propagation crucially depends on reverse transcriptase, an enzyme not present in normal mammalian cells and different from mammalian DNA polymerases, making it a target for specific inhibition. Reverse transcriptase has been well conserved through evolution: an LAV isolate contained a 250-amino-acid-long domain, presumably the reverse transcriptase core sequence, which has 21% homology to Moloney murine leukaemia virus (MoMLV). Because HTLV-III infects only humans and chimpanzees, we substituted murine retroviruses for in vivo evaluation of candidate anti-AIDS drugs after ascertaining similar inhibition in vitro of HTLV-III and MLVs, which were chosen for their short incubation time. The triphosphate of 3'-azido-3'-deoxythymidine (AZT) is incorporated into complementary DNA by retroviral reverse transcriptase, causing premature chain termination. Here we show that chronic AZT treatment of mice infected with Rauscher murine leukaemia virus complex (RLV) prevents infection of splenocytes and development of splenomegaly, and suppresses viraemia if started soon after inoculation. Starting AZT late in the course of disease still leads to significant prolongation of life; anaemia, however is a significant side-effect. By analogy, AZT may have a role in preventing retroviral disease in humans if started early after infection, and it may lead to significant survival gains even if started later in the course of disease.
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PMID:Suppression of mouse viraemia and retroviral disease by 3'-azido-3'-deoxythymidine. 346 67

Purified streptococcal mitogens (SMs) including erythrogenic exotoxin were compared with phytohemagglutinin (PHA) for their ability to sustain lymphadenopathy-associated virus (LAV) replication after the stimulation of normal human peripheral blood mononuclear cells and purified CD4+ and CD8+ T cells infected with LAV. Both SM and PHA supported LAV production in peripheral blood mononuclear and CD4+ cells but not in CD8+ cells. LAV production assessed by the assay of reverse transcriptase in cell supernatants appeared earlier after stimulation with SM and was 6- to 10-fold greater than after stimulation by PHA.
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PMID:High production of the acquired immunodeficiency syndrome virus (lymphadenopathy-associated virus) by human T lymphocytes stimulated by streptococcal mitogenic toxins. 349 Apr 91

Primary cultures from a brain biopsy specimen of a human T-cell lymphotropic virus type III/lymphadenopathy-associated virus (HTLV-III/LAV) seropositive patient with progressive dementia contained small numbers of monocytoid cells and showed reverse transcriptase activity that persisted for as long as 100 days. Electron microscopy of these cells revealed the presence of HTLV-III/LAV virions. Subcultured cells removed from primary cultures by trypsinization were nonspecific esterase negative and did not express virus or show evidence of HTLV-III/LAV proviral sequences, while those remaining in the original flasks were nonspecific esterase positive and continued to produce virus. Virus from primary cultures was transmitted to peripheral blood-derived monocyte-macrophages and T cells. Virus production in T-cell cultures was transient while the monocyte-macrophages, like the primary cultures, produced virus for at least 120 days. Infection of several brain-derived cells with this and another HTLV-III/LAV isolate failed to demonstrate virus replication. These results indicate that the HTLV-III/LAV-infected cells recovered from the brain of this patient are cells of the mononuclear phagocyte series.
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PMID:Virus isolation from and identification of HTLV-III/LAV-producing cells in brain tissue from a patient with AIDS. 349 May 87

Peripheral blood mononuclear cells (PBMNC) from healthy donors immune to the soluble antigens tetanus toxoid (TT) and/or keyhole limpet hemocyanin (KLH) were exposed to infectious human T lymphotropic virus, type III/lymphadenopathy-associated virus (HTLV-III/LAV) with and without prior activation by TT or KLH. After exposure to the virus, PBMNC that had been activated by antigen were 10 to 100 times more susceptible to viral replication, as estimated by measurement of production of reverse transcriptase and viral antigens, than PBMNC that had been preincubated without antigen. In addition, exposure of PBMNC to HTLV-III/LAV led to a loss of lymphocyte blastogenic responses after 2 to 3 wk in culture. HTLV-III/LAV-induced inhibition of lymphocyte blastogenic responses occurred in the absence of detectable production of RT but required the use of live rather than heat-inactivated virus. These results demonstrate that HTLV-III/LAV infection is amplified by antigen-induced activation of PBMNC, and that low levels of HTLV-III/LAV infection in vitro can suppress lymphocyte blastogenic responses. This study provides an in vitro model for the analysis of HTLV-III/LAV-induced immune defects.
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PMID:Amplification of HTLV-III/LAV infection by antigen-induced activation of T cells and direct suppression by virus of lymphocyte blastogenic responses. 349 85


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