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)

Protease inhibitors (PIs) are recently introduced drugs that have improved the survival of HIV-infected patients when given in combination with two reverse transcriptase inhibitors. The HIV-1 protease gene is naturally highly polymorphic. Selection pressure due to IP use can result in major or minor resistance-associated mutations (RAMs). This study investigated whether presence before IP therapy of minor RAMs on the protease gene predicts the virological response. Of the 58 PI-naive patients included in the study, 12 had received two nucleoside reverse transcriptor inhibitors, 14 had received indinavir, 16 ritonavir, and 28 saquinavir-SGC. Viral load was measured on D0 (prior to PI initiation) and at M3 and M6 (Roche Monitor 1.5 with 200 and 20 copies/ml as the thresholds). The protease gene was fully sequenced on D0 using the ABI 377 automatic sequencer after RNA amplification by nested RT-PCR. None of the viral strains exhibited major mutations, but 57 of 58 (98%) had at least one minor mutation (median number of substitutions, 4), 60% had 1 to 4 substitutions, and 40% had 5 to 9 substitutions. Substitutions seen with a prevalence > 20% were located at codons 15, 35, 37, 41, 63, and 77. Numbers of substitutions at M3 and M6 were not correlated with viral load or the nature of the PI used, and neither were they significantly different between patients with more or fewer than 20 copies/ml. These data suggest that the protease genotype at PI initiation does not predict the efficacy of a regimen including a PI and is of no assistance in deciding whether or not to include a PI in a triple combination regimen.
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PMID:[Polymorphism of protease genes in patients infected with HIV-1 and response to therapy including a protease inhibitor]. 1041 38

In order to analyze the impact of protease gene polymorphism on response to regimens containing a protease inhibitor, the entire protease coding domain from 58 human immunodeficiency virus type 1 (HIV-1)-infected patients who were protease inhibitor naive was sequenced before therapy was started. Plasma HIV-1 RNA levels were measured at baseline and at month 3 and month 6 after treatment. All patients were treated with a combination of two reverse transcriptase inhibitors and a protease inhibitor (saquinavir EOF [n = 28], ritonavir [n = 16], or indinavir [n = 14]). Before treatment, 30 different positions whose codons differed from the subtype B consensus sequence were observed. Major mutations associated with protease inhibitor resistance were not observed. No statistical correlation between the number of amino acid differences and the treatment efficacy at month 3 (-2.4 log) or month 6 (-2.7 log) was observed. At baseline, genotypic analysis of the HIV-1 protease gene of patients who have never received a protease inhibitor does not allow prediction of the efficacy of regimens containing a protease inhibitor.
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PMID:Polymorphism of the human immunodeficiency virus type 1 (HIV-1) protease gene and response of HIV-1-infected patients to a protease inhibitor. 1044 74

Better detection of minority human immunodeficiency virus type 1 (HIV-1) populations containing gene mutations may improve the usefulness of antiretroviral resistance testing for clinical management. Molecular cloning of HIV-1 PCR products which might improve minority detection can be slow and difficult, and commercially available recombinant virus assays test drug susceptibility of virus pools. We describe novel plasmids and simple methods for rapid cloning of HIV-1 PCR products from patient specimens and their application to generate infectious recombinant virus clones for virus phenotyping and genotyping. Eight plasmids with differing deletions of sequences encoding HIV-1 protease, reverse transcriptase, or Gag p7/p1 and Gag p1/p6 cleavage sites were constructed for cloning HIV-1 PCR products. A simple HIV-1 sequence-specific uracil deglycosylase-mediated cloning method with the vectors and primers designed here was more rapid than standard ligase-mediated cloning. Pooled and molecularly cloned infectious recombinant viruses were generated with these vectors. Replicative viral fitness and drug susceptibility phenotypes of cloned infectious viruses containing patient specimen-derived sequences were measured. Clonal resistance genotyping analyses were also performed from virus isolates, plasma HIV-1 RNA, and infected cell DNA. Sequencing of a limited number of molecular clones detected minorities of resistant virus not identified in the pooled population PCR product sequence and linkage of minority mutations.
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PMID:Human immunodeficiency virus type 1 cloning vectors for antiretroviral resistance testing. 1044 80

The choice of initial antiretroviral regimen for treating people infected with HIV is crucial to successful long-term control of virus replication. Potent antiretroviral therapy substantially suppresses viral replication as measured by plasma HIV RNA levels to below limits of detection: the current standard of care is usually a combination of at least three drugs and frequently includes a protease inhibitor, or alternatively a non-nucleoside reverse transcriptase inhibitor (nnRTI). Patients who have low CD4+ cell counts (< or = 200 CD4+ cells/mm3) or high plasma HIV RNA levels (> or = 100,000 copies/ml) may not attain maximal suppression of HIV replication when treated with current regimens and may require more aggressive therapy. In contrast, patients with relatively normal CD4+ cell counts and low to non-measurable levels of plasma HIV RNA over prolonged periods (i.e., slow or non-progressors) may not require immediate antiretroviral therapy. These individuals should reconsider treatment when either the CD4+ cell count declines or the HIV RNA level increases. Early and potent antiretroviral therapy should provide more durable virological and clinical benefits for many patients, especially if they receive sufficient counselling and support to aid adherence to the treatment regimen. The optimum time to initiate antiretroviral therapy is not well established, but to maximise the recovery of the immune system and the virological and clinical benefits, initiation of therapy is generally recommended for individuals who have symptoms or those with plasma HIV RNA levels > 5000-10,000 copies/ml, or CD4+ cell counts < 500 cells/mm3. The current choice of initial antiretroviral regimens includes two nucleoside reverse transcriptase inhibitors (nRTI) with a potent, well-tolerated HIV-1 protease inhibitor or nnRTI. Recent short-term activity data (24-week comparative clinical trial data) indicate that regimens combining three nRTI, including abacavir, could also be considered. Other emerging combination regimens for consideration include two HIV-1 protease inhibitors with one or two nRTI, or a combination of drugs from all current categories (e.g., nRTI with a nnRTI and HIV-1 protease inhibitor). The goal of antiretroviral therapy is to maximise suppression of HIV replication and thereby prevent or delay viral resistance, restore immunological function and improve clinical outcome. Since evolution of the virus towards resistance can occur with plasma HIV RNA levels between 50 and 500 copies/ml, current standards for best suppression of HIV replication have shifted to declines in plasma HIV RNA to < 50 copies/ml. In addition, non-adherence to any regimen is associated with the greatest risk for virological failure. Therefore, both the decision to initiate therapy and the choice of initial therapy should be carefully weighted and balanced with the long-term implications of antiretroviral therapy.
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PMID:Antiretroviral therapy in 1999 for antiretroviral-naive individuals with HIV infection. 1054 85

Effect of protein binding on the equilibrium distribution of selected HIV antiviral drugs into isolated human peripheral blood mononuclear cells (PBMC, mainly lymphocytes) was investigated. Human PBMC from a single healthy human donor were isolated, purified, and cryopreserved. Uptake of non-peptide HIV-1 protease inhibitors PNU-96988 and PNU-103017 by these cells in vitro was evaluated as a function of increasing concentration of human serum in the cell incubation media. Both PNU-96988 and PNU-103017 were extensively bound to serum proteins. Uptake/efflux kinetics were very rapid such that accumulation by the cells was thermodynamically, not kinetically, controlled. Accumulation by human PBMCs in vitro was directly proportional to the free and not the total drug concentration in the media. For comparative purposes, the serum protein binding effect on the distribution of two HIV reverse transcriptase (RT) inhibitors, delavirdine (RESCRIPTOR) and zidovudine (AZT), was also evaluated. Like the HIV-1 protease inhibitors, delavirdine was found to be extensively associated with serum proteins and its accumulation by human PBMCs in vitro to be proportional to the free and not total drug concentration. In contrast, AZT was not bound to serum proteins to any significant extent. The uptake of this drug by human PBMCs in vitro was independent of serum concentration. However, the intrinsic cellular accumulation of PNU-96988, PNU-103017 and delavirdine were all greater than AZT. Thus, the extent to which drugs uptake by cells is affected by serum appears proportional to the binding affinity of the serum proteins for the drug.
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PMID:Equilibrium distribution of HIV antiviral drugs into human peripheral blood mononuclear cells (PBMC) is controlled by free drug concentration in the extracellular medium. 1070 5

HIV-positive patients receiving antiretroviral therapy with HIV-1 protease-inhibitors (PI) frequently show insulin-resistance, impaired glucose tolerance, hypertriglyceridaemia and lipodystrophy (LD). LD has often been reported only after the beginning of PI therapy. Some authors link LD to HIV chronic infection, some others suggest that PIs increase pre-existent disturb. Preliminary data of an observational study drawn in IV day-hospital of Spallanzani Institute in Rome showed hypertriglyceridaemia in 36.4% and hyperglycaemia in 11.2% of patients treated with PI. Carr suggests that such drugs should have this lipid-increasing effect because of their inhibition of low density lipoprotein-receptor-related protein, cytoplasmic retinoic-acid binding protein type 1 and P450 3A cytochrome. This theory doesn't explain why both untreated patients and treated with only reverse transcriptase inhibitors show sometimes the same disorders. According to another hypothesis Tumor necrosis factor-alpha, through inhibition of lipoprotein-lipase, would determine high fat-storage in the adipose tissue. Cardiovascular risk factors have always to be assessed before starting a therapy with PI. Glycaemia, triglyceridaemia, cholesterolaemia have to be performed every three months during the treatment and, if necessary, C-Peptide and insulinaemia too. A treatment with lipid-lowering drugs is always recommended in patients with hypertriglyceridaemia > 500 mg/dl and/or hypercholesterolaemia LDL > 190 mg/dl in two following checks. Fibrates have proven to be effective in reducing hypertriglyceridaemia, but there is no certainty that such therapies could have good effects on the LD itself too.
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PMID:[Dysmetabolic syndrome related to HIV-1 protease inhibitors. Review of the literature and personal data]. 1074 53

Molecular alignment remains as one of the most problematic aspects of molecular design. A technique is introduced that facilitates the alignment of a range of structures that could not be handled easily using existing alignment procedures. The flexibility of the method is illustrated with a series of test sets. First, an alignment is performed on a series of molecules from a typical 3D-quantitative structure-activity relationship data set. The results of this test show the technique to outperform many existing alignment methodologies based upon the optimization of molecular similarity of molecular overlaps. This test set is then extended to consider the alignment of more structurally diverse inhibitors of HIV-1 reverse transcriptase and HIV-1 protease. Finally, in the most challenging test, a large protein-based inhibitor is matched with a small-molecule mimic. It is believed that the existence of such a versatile alignment technique will prove invaluable in the fields of molecular design and chemical information handling.
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PMID:Partial molecular alignment via local structure analysis 1076 Nov 57

The ribosome inactivating proteins (RIPs) are a group of proteins that are able to inactivate eukaryotic protein synthesis by attacking the 28S ribosomal RNA. Recent studies have shown that some RIPs possess strong anti-human immunodeficiency virus (HIV) activity. In this study, several common plant RIPs including agrostin, gelonin, luffin, alpha-momorcharin, beta-momorcharin, saporin and trichosanthin were examined for the ability to interfere with HIV-1 replication in a variety of mechanistic assays in vitro. These assays included the CD4/gp120 interaction assay, HIV-1 reverse transcriptase (RT) assay, HIV-1 protease assay and HIV-1 integrase assay. At the concentration of 100 nM, all RIPs appeared to enhance the CD4/gp120 interaction by about 50%. These RIPs exhibited a very weak suppressive effect on HIV-1 RT and on HIV-1 protease. In contrast, with the exception of agrostin, all the RIPs tested could strongly inhibit HIV-1 integrase, the extent of inhibition ranging from 26.1 to 96.3% in an ELISA-based assay. Two RIPs, saporin and luffin, which licited over 90% inhibition in the ELISA-based assay, were further characterized in a radiometric assay. Both of these two RIPs evoked a strong dose-dependent inhibition in the 3'-end processing and strand-transfer activities of integrase. The results from this study suggest that the anti-HIV property of RIPs may be due to inhibition of HIV-1 integrase.
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PMID:The plant ribosome inactivating proteins luffin and saporin are potent inhibitors of HIV-1 integrase. 1076 16

Feline immunodeficiency virus (FIV) protease is structurally very similar to human immunodeficiency virus (HIV) protease but exhibits distinct substrate and inhibitor specificities. We performed mutagenesis of subsite residues of FIV protease in order to define interactions that dictate this specificity. The I37V, N55M, M56I, V59I, and Q99V mutants yielded full activity. The I37V, N55M, V59I, and Q99V mutants showed a significant increase in activity against the HIV-1 reverse transcriptase/integrase and P2/nucleocapsid junction peptides compared with wild-type (wt) FIV protease. The I37V, V59I, and Q99V mutants also showed an increase in activity against two rapidly cleaved peptides selected by cleavage of a phage display library with HIV-1 protease. Mutations at Q54K, I98P, and L101I dramatically reduced activity. Mutants containing a I35D or I57G substitution showed no activity against either FIV or HIV substrates. FIV proteases all failed to cut HIV-1 matrix/capsid, P1/P6, P6/protease, and protease/reverse transcriptase junctions, indicating that none of the substitutions were sufficient to change the specificity completely. The I37V, N55M, M56I, V59I, and Q99V mutants, compared with wt FIV protease, all showed inhibitor specificity more similar to that of HIV-1 protease. The data also suggest that FIV protease prefers a hydrophobic P2/P2' residue like Val over Asn or Glu, which are utilized by HIV-1 protease, and that S2/S2' might play a critical role in distinguishing FIV and HIV-1 protease by specificity. The findings extend our observations regarding the interactions involved in substrate binding and aid in the development of broad-based inhibitors.
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PMID:Alteration of substrate and inhibitor specificity of feline immunodeficiency virus protease. 1077 9

The reproducibility of population-based human immunodeficiency virus type 1 (HIV-1) protease and reverse transcriptase (RT) sequencing was assessed using replicate aliquots of cryopreserved plasma samples obtained from seven heavily treated HIV-1-infected individuals. The sequence of each sample replicate was compared with the consensus sequence for that sample and 99.4% of 35128 amino acids were found to be concordant with the sample consensus. Partial discordances were present at 0.5% of positions and complete discordances were present at <0.1% of positions. To assess the reproducibility at detecting mutations (defined here as differences from the subtype B consensus sequence), the proportion of sequences having a mutation when at least two sequences from that sample had the same mutation were examined. There was a median of 13 protease and 18 RT mutations per sample for a total of 3126 mutations; 95% of these mutations were detected. However, sequencing of multiple clones from two samples demonstrated that those mutations present in a minority of clones were often not detected by population-based sequencing. These results suggest that HIV-1 protease and RT sequencing of circulating plasma virus is highly reproducible but that the sensitivity at detecting mutations may be low if those mutations are present as minor variants.
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PMID:Reproducibility of human immunodeficiency virus type 1 (HIV-1) protease and reverse transcriptase sequencing of plasma samples from heavily treated HIV-1-infected individuals. 1078 89


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