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:2.7.7.6 (RNA polymerase)
34,946 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The existence of extrahepatic reservoirs of hepatitis C virus (HCV) replication remains highly controversial. We searched for the presence of HCV-RNA negative strand in various tissues from eight HCV-infected patients who died of acquired immunodeficiency syndrome (AIDS)-related complications. Negative-strand RNA was detected by a Tth-based reverse-transcriptase polymerase chain reaction (RT-PCR), which was optimized for sensitivity and strand specificity on synthetic RNA templates. This assay was capable of detecting about 10(2) genomic Eq molecules of the correct strand while unspecifically detecting >/=10(8) genomic Eq molecules of the incorrect strand. Negative-strand viral RNA was detected in all but one liver, in lymph nodes (5 cases), in pancreas (5 cases), in adrenal gland (2 cases), in thyroid (2 cases), in bone marrow (1 case), and in spleen (1 case). These data suggest a possible presence of HCV replication sites outside the liver, at least in AIDS patients. Whether these findings relate to various extrahepatic manifestations of HCV infection remains to be determined.
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PMID:Search for hepatitis C virus extrahepatic replication sites in patients with acquired immunodeficiency syndrome: specific detection of negative-strand viral RNA in various tissues. 979 27

Monocytes (MOs) and macrophages (MACs) are well-known targets for HIV-1 infection. Even though the virus load is contributed mainly to lymphocytes during the asymptomatic phase of infection, the expression of HIV-1 in MO/MACs seems to be important for the course of the disease. To establish a model for restricted HIV-1 expression in MACs in vitro, we cultured MO-derived MACs under different culture conditions and analyzed their susceptibility to HIV-1 infection as well as their capacity for virus replication in vitro. MACs cultured under serum-free conditions with M-CSF (M-MACs) remain viable and functionally active as assessed by the analysis of cytokine production. In addition, the levels of CD4, CD14, CCR5, and HLA-DR expression are comparable to those of serum-derived MACs (SER-MACs). However, serum-free MACs were less susceptible to HIV-1 infection, with only 9.5+/-4.5% (mean+/-SEM) of all cells being p24 antigen positive on day 22 as compared with 51+/-9% under serum conditions (p < 0.005). Reverse transcriptase (RT) activity in the culture supernatant of M-MACs was always about 100-fold lower than that of SER-MACs even when comparable amounts of cells were infected. The addition of serum to serum-free cultures increased the percentage of HIV-1 p24 antigen-positive cells (21+/-8% positive cells on day 22) and increased the RT activity, indicating that serum factors could be important for HIV-1 replication in MACs. Therefore we also switched SER-MACs to serum-free culture conditions and found a sharp decrease in RT activity. However, the RT level could always be rescued by the addition of serum, even after a long serum-free culture period. This effect was dependent on the serum concentration added, with as little as 0.1% serum being effective in reestablishing viral production as measured by RT activity. In conclusion, we show that serum has an important role in the replication of HIV-1 in MACs. Our results suggest that besides the role of CD4 and CCR5 other microenvironmental factors, e.g., growth factors, cytokines, or hormones, which are not provided by the target cell itself, are involved in the regulation of MAC infection and of replication by HIV-1.
AIDS Res Hum Retroviruses 1998 Nov 20
PMID:Restricted HIV type 1 replication under serum-free culture conditions in human monocyte-derived macrophages. 984 Feb 91

This paper presents the evolution during its follow-up of a virostatic combination study of the type I-II trial conducted on ten AIDS-related complex (ARC) or acquired immunodeficiency syndrome (AIDS) patients [1, 9, respectively]. Its concept is based on the following original notions: a) it is not the number of the virostatics applied to each patient at any phase which determines their effect; it is the number of affected virus targets which determines the effect. Thus, the so called "tritherapies", imposed by the "AIDS Command" to thousands of patients selected at random, to be compared to the same number of subjects receiving only "bi" or "monotherapies", might be beginning to face failure because they attack only two targets: retro-transcriptase and HIV1 protease. Having discovered, owing to our experimental screening, original HIV1 virostatics, acriflavine (ACF) and several ellipticine analogues among which we have used methyl-hydroxy-ellipticine (MHE), we are able to attack two virus targets unaffected by classical virostatics: ACF attacks DNA, from its integrated double branched stage to the provirus one, and MHE inhibits topoisomerase II. We experimentally combined these two agents with AZT, which inhibits retro-transcriptase, thus we realized a combination affecting three targets. This three agent combination was able to eradicate Friend's virus from infected mice. Clinically, combinations of three drugs affecting four targets (as they are selected among the ten virostatics available today) give a stronger result than three drug combinations affecting only three targets, because they were selected from the five virostatics which were the only ones available at the beginning of the present study. Five patients out of five who received the combinations of four virostatics chosen among the ten currently available (thus affecting four targets) from the beginning of their treatment to the present have all reduced their viral load (VL) and maintained it below the detectable level (< 200 RNA copies/mL then 20 copies/mL); b) as the toxicities of virostatics and as HIV1 resistances may happen as soon as 12 weeks of treatment, the combinations have been, in our study, applied in shorter (3 week) sequences, differing from each other due to drug rotation; c) neither toxicity nor resistance occurred; d) curiously, the CD4 numbers, even when they increased rapidly, has never attained their normal count, and their curve may be a Gombertzian one. This CD4 restoration limitation can be due to persisting virus, as indicated in some patients by small peaks which may appear on some VL plateaus, though they disappear without treatment change.
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PMID:Combinations of three or four HIV virostatics applied in short sequences which differ from each other by drug rotation. Preliminary results of the viral loads and CD4 numbers. 986 98

A high incidence of herpes zoster was noticed among patients with AIDS, shortly after addition of a protease inhibitor to their baseline treatment with nucleoside analogue reverse-transcriptase inhibitors. Within a median follow-up of 64 weeks (range, 34-103 weeks), 14 patients (7%) had a first episode or a recurrence of herpes zoster (6.2 episodes per 100 patient-years). No episodes of zoster were diagnosed before week 4. Twelve episodes (86%) occurred between weeks 4 and 16. The risk of zoster was independent of age, sex, type of protease inhibitor, and CD4+ lymphocyte count and viral load at baseline and month 1. A CD8+ lymphocyte proportion at baseline of > 66% (hazard ratio [HR], 10.6; 95% confidence interval [CI], 3.4-33.1) and an increase in CD8+ lymphocyte proportion at month 1 of > 5% (HR, 32; 95% CI, 8.1-126.4) were independently associated with the risk of herpes zoster. These data might be clinically useful for determining transient prophylaxis for those patients at high risk.
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PMID:High incidence of herpes zoster in patients with AIDS soon after therapy with protease inhibitors. 986 69

The kinetics of non treated and especially of treated HIV1 is compared to that of non treated and of treated cancer cells. Contrary to Skipper's scheme, based on constancy of cancer cell proliferation or post-chemotherapy decrease slope, the same chemotherapy successive cycles decrease in fact less and less the proportion of cell number reduction, and the hope of killing the "last cell" is a utopian concept. Hence, the very poor global benefit in cancer medicine registered in the last 50 years. The only cures are seen in child tumors and young adults testis cancer: the immunity reaction being stronger before 40 years of age than after 40 may explain this difference with age. The a priori systematic opposition to active immunotherapy of cancer from some authorities has been a grave fault. Such fault should not be committed for the treatment of HIV1-AIDS complex. The continuous HIV1 so called intensive virostatic chemotherapy is complicated by severe toxicities, and resistances of relapses and virus re-activation when it must be discontinued. The widely accepted triple therapy only affects two virus targets (retro-transcriptase and virus protease), which is insufficient, as we have shown. We have also observed that the constant and most rapid VL decrease to < 200 or < 20 RNA copies/mL is obtained when four virus targets are affected, including some concerning DNA provirus (which is the case of acriflavine and methylhydroxy-ellipticine). As in acute lymphoid leukemia, two treatment phases can be distinguished: a) the VL reduction to 20 copies; b) the maintenance of the residual < 20 copies of viruses. Excellent results as far as VL decrease and maintenance at < 20 copies have been obtained with a follow-up between 1 1/2 and 6 years, without any toxicity nor global resistance, with combinations of four drugs affecting four viral targets, applied in short (3 week) sequences, different from each others owing to drug rotation. This can be compared with the 65% remission rate obtained with alternative different cycles of cancer chemotherapy in tumors resistant to conventional modalities. The possibility of repeating for ten patients the evaluation of viral load and of immunologic parameters has allowed us to discover that some VL decrease curves are fractal. As well, maintenance 20 copies are not rarely interrupted by short and reversible HIV1 rebounds as those we had described in "cured" acute lymphoid leukemia patients. Of utmost importance, all HIV1 rebounds were associated with the presence of one cofactor: chimerism, chronic hepatitis, CMV, herpes 8, herpes 6, and influenza are those we observed. The problem today is not to "kill the last tumor cell in cancer" or "the last HIV1 particle" in HIV1-AIDS complex. It is to keep the residual cells or virus in latency. Active immunotherapy and other biologic interventions, such as hypermethylation, should be studied in this aim, as they are also able to do so.
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PMID:The kinetics of cancer cells and of HIV1: the problems of cell and virus rebounds and of latency. 992 9

The recent discovery of chemokine receptors as coreceptors for human immunodeficiency virus-type 1 (HIV-1) entry offers new avenues for investigating the pathogenesis of acquired immunodeficiency syndrome (AIDS)-related cytopenias. To this end, we sought to (1) phenotype human hematopoietic cells for CD4 and the HIV-1 coreceptors CXCR4, CCR5, CCR3, and CCR2b; (2) correlate CD4 and chemokine receptor expression with their susceptibility to HIV-1 infection; and (3) examine any potential interplay between inflammatory cytokines released during HIV-1 infection and regulation of chemokine receptor expression. Fluorescence-activated cell sorting (FACS) analysis of bone marrow mononuclear cells (BMMNC), cells derived from serum-free expanded hematopoietic lineages (colony-forming unit-granulocyte-macrophage [CFU-GM], colony-forming unit-megakaryocyte [CFU-Meg], and burst-forming unit-erythroid [BFU-E]), and CD34(+) cells showed differential expression of chemokine receptors and CD4 with some lineage specificity. Significantly, FACS-sorted CXCR4(+)/CD34(+) cells had the same clonogeneic potential as CXCR4(-)/CD34(+) cells. Reverse transcriptase-polymerase chain reaction (RT-PCR) analysis of FACS-sorted human candidate stem cells (HSC; CD34(+), c-kit+, Rho123(low)) showed the presence of CXCR4 mRNA but not CD4 mRNA. Infection studies with HIV-1 Env-pseudotyped luciferase reporter viruses indicated that X4 Env (CXCR4-using) pseudotypes infected megakaryocytic cells, whereas R5 Env (CCR5-using) pseudotypes did not. Similarly, R5 but not X4 Env-pseudotyped viruses infected granulocyte-macrophage cells in a CD4/CCR5-dependent manner. Erythroid cells were resistant to R5 or X4 viral infection. Finally, we found that gamma-interferon treatment upregulated CXCR4 expression on primary hematopoietic cells. In summary, the delineation of chemokine receptor expression on primary hematopoietic cells is a first step towards dissecting the chemokine-chemokine receptor axes that may play a role in hematopoietic cell proliferation and homing. Furthermore, susceptibility of hematopoietic cells to HIV-1 infection is likely to be more complicated than the mere physical presence of CD4 and the cognate chemokine receptor. Lastly, our results suggest a potential interplay between gamma-interferon secretion and CXCR4 expression.
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PMID:Coreceptor/chemokine receptor expression on human hematopoietic cells: biological implications for human immunodeficiency virus-type 1 infection. 994 56

HIV-1 gene expression relies upon a complex machinery that is primarily controlled by two viral regulatory proteins, Tat and Rev. Rev is involved in regulating post-transcriptional events of HIV-1 gene expression. The Tat protein transactivates transcription from the HIV-1 5' long terminal repeat (LTR) and acts in synergy with specific cellular factors. Recently, it has been shown that one set of these cellular factors is a protein kinase activity termed TAK (Tat-associated kinase), which activates transcription by hyperphosphorylation of the carboxyl-terminal domain (CTD) of the large subunit of RNA polymerase II. TAK also enhances transcription of HIV-2, together with the retroviral transactivator, Tat-2. The TAK activity appears to be related to the CTD kinase P-TEFb, which stabilizes transcription elongation of many genes and was originally isolated from Drosophila extracts. Both TAK and P-TEFb contain at least two subunits: the cyclin-dependent kinase, CDK9 (PITALRE), the catalytic subunit, and the regulatory subunit, cyclin T1. CDK9 and cyclin T1 are ubiquitous factors that affects many cellular processes, including cell differentiation and apoptosis. The involvement of TAK in HIV-1 and HIV-2 gene expression is an important aspect in the biology of these two retroviruses, and may lead to the development of novel antiretroviral drugs and/or gene therapy approaches for the treatment of patients with AIDS.
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PMID:Regulatory functions of Cdk9 and of cyclin T1 in HIV tat transactivation pathway gene expression. 1053 59

In the brain of patients with AIDS, HIV-1 is localised in a productive form in mononuclear cells. One issue that still needs clarification is whether HIV is localised in cells other than those of mononuclear lineage. Gene amplification by polymerase chain reaction/in situ hybridisation (PCR-IS) could shed light on it. In this study, formalin-fixed, paraffin-embedded brain tissue from ten adult AIDS sufferers was used. Five of them showed evidence of HIV encephalitis (HIVE), five did not show any abnormality. Nested PCR revealed HIV-1 DNA in all HIVE cases and in three of the group without HIVE. HIV-1 DNA and RNA were also detected in situ in seven cases (all seven were also HIV-1 DNA positive in tube). A higher signal was located in the white than in the grey matter. HIV-1 DNA was found in microglia, macrophages, perivascular cells, multinucleated gaint cells (MGC) and in CD68-negative cells. Some of them were identified as endothelial cells, astrocytes and oligodendrocytes. Reverse transcriptase-PCR-IS was positive in macrophages, MGC, endothelial and glial cells. These results confirm infection of endothelial cells and other glial cells and give clues about the route of entry of virus into the central nervous system and the pathogenesis of the disease. This study did not give any convincing evidence supporting an infection of neurons by HIV-1.
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PMID:Detection and localisation of HIV-1 DNA and RNA in fixed adult AIDS brain by polymerase chain reaction/in situ hybridisation technique. 1054 71

CD40 ligand (CD40L), expressed on activated T cells, binds its receptor, CD40, on dendritic cells, B cells, and monocytes/ macrophages. Human immunodeficiency virus (HIV)-infected individuals exhibit normal B-cell CD40 expression but diminished expression of CD40L on CD4 + T cells. Thus, we studied recombinant human CD40L (huCD40L) in an in vitro rhesus macaque model of acquired immunodeficiency syndrome (AIDS). huCD40L induced peripheral blood mononuclear cell (PBMC) proliferation independent of mitogenic cytokines and led to a 70% reduction in p27 production by simian immunodeficiency virus (SIV) mac239 infected PBMCs (P < 0.05). Reverse transcriptase-polymerase chain reaction (RT-PCR) analysis showed reduced expression of SIV gag and increased expression of interleukin (IL)-16 mRNA. Supernatants from huCD40L-stimulated PBMC and control cultures contained similar amounts of IL-16, suggesting an intracellular antiviral effect by IL-16. Phytohemagglutinin (PHA)-stimulated PBMCs similarly cultured with huCD40L showed only slight increases in chemokine production (P > 0.05). These results suggest that huCD40L inhibits replication (antigen and mRNA production) of SIVmac239. This response involves huCD40L induction of IL16 mRNA expression and appears to be independent of beta-chemokines.
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PMID:Recombinant human CD40 ligand inhibits simian immunodeficiency virus replication: a role for interleukin- 16. 1059 85

The extraordinarily high mutation rate of HIV suggests that the viral population exists near the threshold for viral viability. An increase in mutation could mediate a lethal increase in the already high proportion of defective viruses. We initially tested this hypothesis by culturing HIV-infected cells in mutagenic deoxyribonucleoside analogs. In the presence of 5-hydroxydeoxycytidine, there was a loss of viral replication after sequential passages of HIV in human CEM cells (Loeb LA, et al.: Proc Natl Acad Sci USA 1999;96:14921497). We now propose to use mutagenic ribonucleosides to induce lethal mutagenesis. The incorporation of mutagenic analogs into the HIV genome by the host cell RNA polymerase, rather than by the viral reverse transcriptase, augurs well for the avoidance of resistant viruses.
AIDS Res Hum Retroviruses 2000 Jan 01
PMID:Lethal mutagenesis of HIV by mutagenic ribonucleoside analogs. 1062 10


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