Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “reverse transcriptase”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 1,423 records · Page 79Linked to original sources
PubMed2001

Functional multimerization of the human telomerase reverse transcriptase.

The telomerase enzyme exists as a large complex (approximately 1,000 kDa) in mammals and at minimum is composed of the telomerase RNA and the catalytic subunit telomerase reverse transcriptase (TERT). In Saccharomyces cerevisiae, telomerase appears to function as an interdependent dimer or multimer in vivo (J. Prescott and E. H. Blackburn, Genes Dev. 11:2790-2800, 1997). However, the requirements for multimerization are not known, and it remained unclear whether telomerase exists as a multimer in other organisms. We show here that human TERT (hTERT) forms a functional multimer in a rabbit reticulocyte lysate reconstitution assay and in human cell extracts. Two separate, catalytically inactive TERT proteins can complement each other in trans to reconstitute catalytic activity. This complementation requires the amino terminus of one hTERT and the reverse transcriptase and C-terminal domains of the second hTERT. The telomerase RNA must associate with only the latter hTERT for reconstitution of telomerase activity to occur. Multimerization of telomerase also facilitates the recognition and elongation of substrates in vitro and in vivo. These data suggest that the catalytic core of human telomerase may exist as a functionally cooperative dimer or multimer in vivo.

Catalysis↗
PubMed2002

Advances in QSAR studies of HIV-1 reverse transcriptase inhibitors.

A review is presented of the recent advances in quantitative structure-activity relationship (QSAR) studies of HIV-1 reverse transcriptase (RT) inhibitors. These inhibitors have been put into two classes: nucleoside RT inhibitors (NRTIs), which are 2',3'-dideoxynucleoside analogues (ddNs), and non-nucleoside RT inhibitors (NNRTIs). For NRTIs (ddNs), which act as competitive inhibitors or alternate substrates of RT and hence interact at the substrate binding site of the enzyme, QSARs have pointed out the major role of the electronic factors governing their activity. For NNRTIs, which bind to a site entirely distinct from the substrate binding site, the activity has been shown to be largely dependent upon the hydrophobic nature of the compounds or substituents. The hydrophobic nature of the active site in the receptor with which the NNRTIs interact provides relatively few possibilities for the molecules to have polar interactions or hydrogen bondings, but QSARs have indicated that NNRTIs do involve some polar interactions and hydrogen bondings with some pockets of the enzyme. QSARs also indicate the significant roles of steric interactions and conformational shape of the molecule.

Algorithms↗
PubMed2006

R5 variants of human immunodeficiency virus type 1 preferentially infect CD62L- CD4+ T cells and are potentially resistant to nucleoside reverse transcriptase inhibitors.

The persistence of human immunodeficiency virus type 1 (HIV-1) in memory CD4+ T cells is a major obstacle to the eradication of the virus with current antiretroviral therapy. Here, we investigated the effect of the activation status of CD4+ T cells on the predominance of R5 and X4 HIV-1 variants in different subsets of CD4+ T cells in ex vivo-infected human lymphoid tissues and peripheral blood mononuclear cells (PBMCs). In these cell systems, we examined the sensitivity of HIV replication to reverse transcriptase inhibitors. We demonstrate that R5 HIV-1 variants preferentially produced productive infection in HLA-DR- CD62L- CD4+ T cells. These cells were mostly in the G1b phase of the cell cycle, divided slowly, and expressed high levels of CCR5. In contrast, X4 HIV-1 variants preferentially produced productive infection in activated HLA-DR+ CD62L+ CD4+ T cells, which expressed high levels of CXCR4. The abilities of the nucleoside reverse transcriptase inhibitors (NRTI) zidovudine and lamivudine to stop HIV-1 replication were 20 times greater in activated T cells than in slowly dividing HLA-DR- CD62L- CD4+ T cells. This result, demonstrated both in a highly physiologically relevant ex vivo lymphoid tissue model and in PBMCs, correlated with higher levels of thymidine kinase mRNA in activated than in slowly dividing HLA-DR- CD62L- CD4+ T cells. The non-NRTI nevirapine was equally efficient in both cell subsets. The lymphoid tissue and PBMC-derived cell systems represent well-defined models which could be used as new tools for the study of the mechanism of resistance to HIV-1 inhibitors in HLA-DR- CD62L- CD4+ T cells.

CD4-Positive T-Lymphocytes↗
PubMed1999

Suppression of resistance to drugs targeted to human immunodeficiency virus reverse transcriptase by combination therapy.

There are currently thirteen drugs approved for the treatment of human immunodeficiency virus (HIV)-infected individuals. Seven of them are targeted against the virus-encoded reverse transcriptase (RT). Appearance of drug-resistant virus strains under the selective pressure of anti-HIV chemotherapy rapidly occurs as a consequence of the low fidelity of the RT-catalyzed DNA polymerisation reaction and the massive viral turnover. Resistance-associated mutations appear in the RT of virus strains that are under selective pressure of both nucleoside RT inhibitors (NRTIs) and non-nucleoside RT inhibitors (NNRTIs). A variety of these mutations cause cross-resistance to several other NRTIs or NNRTIs and consequently may hamper the effectiveness of the other drugs. Other RT mutations are quite specific and selective in their drug-resistance spectrum and do not influence the potency of the majority of other available drugs. Moreover, drug-specific mutations are identified that are able to restore drug sensitivity again when concomitantly present with other drug-specific mutations. Combination therapy has proven to be able to markedly suppress virus replication (and subsequent appearance of drug resistance) for a relatively long time period. However, in a number of cases, multiple drug combination therapy results in the appearance of a different mutation spectrum than is expected to emerge under monotherapy. Also, it has been shown that drugs that alter cellular deoxynucleotide pools not only are able to potentiate the antiviral efficacy of some RT inhibitors, but also may influence the resistance spectrum of certain anti-HIV drugs. All available information argues for the use of a rational combination of different anti-HIV inhibitors with different resistance spectra to suppress virus replication efficiently and to delay the emergence of drug-resistant virus as long as possible, but it also indicates that there is a strong need for additional drugs to further optimize and improve the efficacy of long-term HIV treatment.

Anti-HIV Agents↗
PubMedDate not supplied

Combination therapy with indinavir, ritonavir, and delavirdine and nucleoside reverse transcriptase inhibitors in patients with HIV/AIDS who have failed multiple antiretroviral combinations.

PURPOSE: Ritonavir (RTV) and delavirdine (DLV) are inhibitors of cytochrome P450 (CYP) 3A4, the specific CYP that metabolizes indinavir (IDV). We hypothesized that patients who have failed multiple therapies containing protease inhibitors would still respond to IDV if high plasma concentrations were achieved. We retrospectively examined the antiviral efficacy of the combination of RTV, DLV, and IDV in heavily antiretroviral-experienced patients. METHOD: A chart review of patients treated with IDV/RTV/DLV and two nucleoside reverse transcriptase inhibitor (NRTI) drugs was performed. Only patients who failed at least three highly active antiretroviral therapy (HAART) regimens and remained on IDV/RTV/DLV therapy for at least 2 months were included. Plasma concentrations for IDV and RTV were obtained if patients were still on therapy. RESULTS: Ten participants were identified who qualified for this study. The median plasma HIV RNA prior to initiating IDV/RTV/DLV was 359,300 copies/mL. Nine of the 10 patients had failed nonnucleoside reverse transcriptase inhibitor (NNRTI)-containing regimens in the past. Eight out of 10 patients had at reduction in HIV RNA. Four of eight patients maintained the 1 log(10) reduction in HIV RNA past 6 months. Mean CD4 cell count increased from 142+/-99 to 273+/-126 cells/mm(3). Genotypic data available on six patients showed multiple protease gene mutations. Plasma concentration of IDV in three patients (two troughs and one 7 hours postdose) were >1,000 ng/mL. CONCLUSION: Our data suggests that in heavily antiretroviral drug-treated patients, partial antiretroviral response to RTV/IDV/DLV can still be achieved. The use of IDV/RTV/DLV and two NRTIs as salvage therapy has merit in patients who have no viable treatment options. A prospective trial utilizing this drug combination is warranted.

Adult↗
PubMed2002

High prevalence of genotypic resistance to nucleoside reverse transcriptase inhibitors among therapy-naive individuals from the Warsaw cohort.

BACKGROUND: The purpose of this study was to recognize nucleoside reverse transcriptase inhibitor (NRTI)-resistant HIV-1 strains among a group of therapy-naive patients, and subsequently to guide the choice of antiretroviral therapy. PATIENTS AND METHODS: HIV strains present in sera of 128 antiretroviral therapy-naive patients were tested for NRTI resistance-associated mutations. The RT-PCR amplified HIV rt regions were analyzed with an INNI-LiPA-HIV-1 RT assay. The number and pattern of resistance-associated mutated codons were determined and interpreted as resistance to particular drugs. RESULTS: Mutated codons were detected in 66 (51.5%) out of 128 tested samples. In 54 (81.8%) out of 66 samples, a K70R mutation was identified, which was followed by an M184V mutation in 22 cases (33.3%). For a majority of these samples, mixed wild/mutant populations were recognized in 44 (66.6%) cases. The interpretation of hybridization data revealed drug-resistant strains in 37 (28.9%) out of all samples tested. The determined resistance to particular drugs was as follows: 20 strains were resistant to zidovudine (ZDV), ten to lamivudine (3TC) and six to didanosine (ddI)/zalcitabine (ddC)/abacavir (ABC). In one case, a ZDV/3TC-resistant HIV strain was found. CONCLUSION: The prevalence of mutations associated with NRTI resistance was high in the tested cohort. The key reasons for that were most probably needle and drug sharing within the group of intravenous drug users (IVDUs) and the use of ZDV in monotherapeutic regimes in the early 1990s.

Acquired Immunodeficiency Syndrome↗
PubMed1998

Novel nonnucleoside inhibitors of HIV-1 reverse transcriptase. 8. 8-Aryloxymethyl- and 8-arylthiomethyldipyridodiazepinones.

Nevirapine (I) is the first human immunodeficiency virus type 1 (HIV-1) nonnucleoside reverse transcriptase (RT) inhibitor to reach regulatory approval. As a result of a second generation program around the tricyclic core system of nevirapine, 2-chloro-5, 11-dihydro-11-ethyl-5-methyl-8-(2-(pyridin-4-yl)ethyl)-6H-dipyrido[3, 2-b:2',3'-e][1,4]diazepin-6-one (II)1a and 2-chloro-5, 11-dihydro-11-ethyl-5-methyl-8-phenylethyl-6H-dipyrido[3,2-b:2', 3'-e][1,4]diazepin-6-one (III)1a were identified as broad spectrum HIV-1 RT inhibitors. A detailed examination of replacing either of the methylenes of the 8-ethyl linker of II or III is presented. It was found that 8-aryloxymethyl and 8-arylthiomethyl are the preferred pattern of substitution for potency against RT. The most potent compounds were further evaluated against a panel of clinically significant mutant RT enzymes (K103N, V106A, G190A, P236L) and in cytotoxicity and in vitro metabolism assays. The most potent compound was 2-chloro-8-phenylthiomethyl analogue 37 which displayed sub-100 nM activity against all HIV-1 RT enzymes tested.

Animals↗
PubMed2004

The reverse transcriptase (RT) mutation V118I is associated with virologic failure on abacavir-based antiretroviral treatment (ART) in HIV-1 infection.

Antiviral efficacy and serum lipids were investigated following a switch from long-term successful protease inhibitor based antiretroviral treatment (PI-ART) to abacavir-based ART in 29 patients who have been followed for 28 months thereafter. Virologic failure occurred within 3 months in 21% (6/29) of the patients, and abacavir hypersensitivity in 1 individual. The remaining 22 patients continue to have HIV RNA < 50 copies/ml after 28 months with a CD4 increase from 605 +/- 265 x 10(6)/l to 798 +/- 366 x 10(6)/l (p < 0.001). All virologic failing patients had been on long-term unsuccessful nucleoside reverse transcriptase inhibitor (NRTI) therapy before PI-ART as compared to 32% (7/22) of the virologic non-failing patients (p < 0.01). The viral strains from the virologic failing patients harboured 3-6 reverse transcriptase (RT) mutations, including the V118I mutation in 5/6 cases prior to PI-ART or at viral rebound. Only the V118I RT mutation was statistically more common among virologic failing than non-failing NRTI pretreated patients (p < 0.05). Stepwise multiple regression analysis for viral failure resulted in a model with only the V118I RT mutation entering the model (p < 0.01). The LDL cholesterol and triglyceride values decreased and the HDL cholesterol increased after the switch to abacavir-based ART (p < 0.01, p < 0.05, p < 0.05, respectively). In conclusion, viral failure was associated with prior mono- or dual-NRTI treatment and the occurrence of the V1181 RT mutation, persisting despite long term viral control. The selection process for patients suitable for treatment simplification to abacavir-based ART should contain a detailed antiretroviral treatment history.

Adult↗
PubMed2002

Evaluation of a quantitative product-enhanced reverse transcriptase assay to monitor retrovirus in mAb cell-culture.

Murine hybridoma cells used in the production of monoclonal antibodies (mAbs) produce endogenous type C retrovirus particles. Regulatory agencies require a demonstration that mAbs intended for human use are free of retrovirus with an adequate margin of safety. This is usually achieved by evaluation studies, performed at small scale, to demonstrate that the manufacturing process is capable of removing or inactivating several different model viruses, including a murine retrovirus. In a previous report, we demonstrated the utility of TaqMan fluorogenic 5'-nuclease product-enhanced reverse transcriptase (TM-PERT) assays for measuring reverse transcriptase (RT) activity in laboratory-scale cell-culture samples and RT removal by laboratory-scale models of processing steps. In this report, we evaluate the specificity, accuracy, range, precision and robustness of TM-PERT for this purpose. We find that this assay detects RT activity contained in xenotropic murine leukemia virus (X-MuLV) and CHO cell type C particles and quantifies particle numbers comparably to other assays (e.g. transmission electron microscopy, viral sequence specific TaqMan). Cell derived DNA polymerases appear to contribute only modestly to the assay background and RT activity in clarified cell culture harvests is contained largely in Type C particles. TM-PERT is linear and precise between 10(7)and 10(13) pU/ml, establishing the assay range. The assay is robust in that test article storage condition and DNA/protein content had little impact on assay performance. Thus, TM-PERT appears to be an acceptable assay to measure type C particles in rodent cell culture samples.

Animals↗
PubMed2006

A peptide with HIV-1 reverse transcriptase inhibitory activity from the medicinal mushroom Russula paludosa.

Hot water extracts of 16 species of mushrooms, including both edible and medicinal mushrooms, were screened for human immunodeficiency virus (HIV)-1 reverse transcriptase (RT) inhibitory activity. Extracts of Lactarius camphoratus, Trametes suaveolens, Sparassis crispa, Pleurotus sajor-caju, Pleurotus pulmonarius, and Russula paludosa elicited over 50% inhibition when tested at the concentration of 1 mg/ml. The extract of R. paludosa demonstrated the highest inhibitory activity on HIV-1 RT (97.6%). Fraction SU2, purified from R. paludosa extract by anion exchange chromatography on DEAE-cellulose and gel filtration on Superdex 75, exhibited potent inhibitory activity on HIV-1 RT. At the concentrations of 1 mg/ml, 0.2 mg/ml, and 0.04 mg/ml, the inhibition ratios were 99.2%, 89.3%, and 41.8%, respectively, giving an IC50 of 11 microM. The molecular mass of SU2 was 4.5 kDa and its N-terminal amino acid sequence was determined to be KREHGQHCEF. The peptide was devoid of hemagglutinating, ribonuclease, antifungal, protease, protease inhibitory, and laccase activities.

Agaricales↗
PubMed2000

Site-specific incorporation of nucleoside analogs by HIV-1 reverse transcriptase and the template grip mutant P157S. Template interactions influence substrate recognition at the polymerase active site.

Studies of drug-resistant reverse transcriptases (RTs) reveal the roles of specific structural elements and amino acids in polymerase function. To characterize better the effects of RT/template interactions on dNTP substrate recognition, we examined the sensitivity of human immunodeficiency virus type 1 (HIV-1) RT containing a new mutation in a "template grip" residue (P157S) to the 5'-triphosphates of (-)-beta-2',3'-dideoxy-3'-thiacytidine (3TC), (-)-beta-2',3'-dideoxy-5-fluoro-3'-thiacytidine (FTC), and 3'-azido-3'-deoxythymidine (AZT). A primer extension assay was used to monitor quantitatively drug monophosphate incorporation opposite each of multiple target sites. Wild-type and P157S RTs had similar catalytic activities and processivities on heteropolymeric RNA and DNA templates. When averaged over multiple template sites, P157S RT was 2-7-fold resistant to the 5'-triphosphates of 3TC, FTC, and AZT. Each drug triphosphate inhibited polymerization more efficiently on the DNA template compared with an RNA template of identical sequence. Moreover, chain termination by 3TC and FTC was strongly influenced by template sequence context. Incorporation of FTC and 3TC monophosphate varied up to 10-fold opposite 7 different G residues in the DNA template, and the P157S mutation altered this site specificity. In summary, these data identify Pro(157) as an important residue affecting nucleoside analog resistance and suggest that interactions between RT and the template strand influence dNTP substrate recognition at the RT active site. Our findings are discussed within the context of the HIV-1 RT structure.

Catalytic Domain↗
PubMed2000

Selective interaction of the human immunodeficiency virus type 1 reverse transcriptase nonnucleoside inhibitor efavirenz and its thio-substituted analog with different enzyme-substrate complexes.

Accumulating data have brought the nonnucleoside reverse transcriptase (RT) inhibitors (NNRTIs) into the forefront of antiretroviral therapy. Among the emerging compounds in this class, a particularly attractive one is efavirenz (Sustiva), recently approved for clinical use by the U.S. Food and Drug Administration. In the present study, the equilibrium dissociation constants for efavirenz binding to the different catalytic forms of human immunodeficiency virus type 1 RT as well as the association and dissociation rates have been determined using a steady-state kinetic approach. In addition, the same enzymological analysis has been extended to the thio-substituted analog, sefavirenz, which showed comparable activity in vitro against RT. Both compounds have been found to act as purely uncompetitive inhibitors at low drug concentrations (5 to 50 nM) and as mixed noncompetitive inhibitors at higher doses (50 to 500 nM). This behavior can be interpreted in terms of the relative affinities for the different catalytic forms of the enzyme. Both efavirenz and sefavirenz showed increasing affinities for the different forms of RT in the following order: free enzyme < (i.e., bound with lower affinity) binary RT-template-primer (TP) complex < ternary RT-TP-deoxynucleoside triphosphate (dNTP) complex. The rate of binding of the two inhibitors to the different enzyme-substrate complexes was well below the diffusion limit (on the order of 10(4) M(-1) s(-1)); however, both inhibitors, when bound to the ternary RT-TP-dNTP complex, showed very low dissociation rates, on the order of 10(-4) s(-1) for both compounds, typical of tightly binding inhibitors. Thus, efavirenz and its thio-substituted derivative sefavirenz appear to be peculiar in their mechanism of action, being selective tightly binding inhibitors of the ternary RT-TP-dNTP complex. Efavirenz is the first clinically approved NNRTI to show this property.

Alkynes↗
PubMed2005

Accurate prediction of HIV-1 drug response from the reverse transcriptase and protease amino acid sequences using sparse models created by convex optimization.

MOTIVATION: Genotype-phenotype modeling problems are often overcomplete, or ill-posed, since the number of potential predictors-genes, proteins, mutations and their interactions-is large relative to the number of measured outcomes. Such datasets can still be used to train sparse parameter models that generalize accurately, by exerting a principle similar to Occam's Razor: When many possible theories can explain the observations, the most simple is most likely to be correct. We apply this philosophy to modeling the drug response of Type-1 Human Immunodeficiency Virus (HIV-1). Owing to the decreasing expense of genetic sequencing relative to in vitro phenotype testing, a statistical model that reliably predicts viral drug response from genetic data is an important tool in the selection of antiretroviral therapy (ART). The optimization techniques described will have application to many genotype-phenotype modeling problems for the purpose of enhancing clinical decisions. RESULTS: We describe two regression techniques for predicting viral phenotype in response to ART from genetic sequence data. Both techniques employ convex optimization for the continuous subset selection of a sparse set of model parameters. The first technique, the least absolute shrinkage and selection operator, uses the l(1) norm loss function to create a sparse linear model; the second, the support vector machine with radial basis kernel functions, uses the epsilon-insensitive loss function to create a sparse non-linear model. The techniques are applied to predict the response of the HIV-1 virus to 10 reverse transcriptase inhibitor and 7 protease inhibitor drugs. The genetic data are derived from the HIV coding sequences for the reverse transcriptase and protease enzymes. When tested by cross-validation with actual laboratory measurements, these models predict drug response phenotype more accurately than models previously discussed in the literature, and other canonical techniques described here. Key features of the methods that enable this performance are the tendency to generate simple models where many of the parameters are zero, and the convexity of the cost function, which assures that we can find model parameters to globally minimize the cost function for a particular training dataset. AVAILABILITY: Results, tables and figures are available at ftp://ftp.genesecurity.net. SUPPLEMENTARY INFORMATION: An Appendix to accompany this article is available at Bioinformatics online.

Amino Acid Sequence↗
PubMed1993

Synthesis and evaluation of 2-pyridinone derivatives as HIV-1-specific reverse transcriptase inhibitors. 4. 3-[2-(Benzoxazol-2-yl)ethyl]-5-ethyl-6-methylpyridin-2(1H)-one and analogues.

A new series of potent specific 2-pyridinone reverse transcriptase (RT) inhibitors was developed based on the preliminary development lead 3-[(phthalmido)ethyl]-5-ethyl-6-methylpyridin-2(1H)-one (3), a non-nucleoside derivative which exhibited weak antiviral activity in cell culture against HIV-1 strain IIIB. One compound, 3-[(benzoxazol-2-yl)ethyl]-5-ethyl-6-methylpyridin-2(1H)-one (9,L-696,229), which was a highly selective antagonist of the RT enzyme (IC50 = 23 nM) and which inhibited the spread of HIV-1 IIIB infection by > 95% in MT4 human T-lymphoid cell culture (CIC95 = 50-100 nM), was selected for clinical evaluation as an antiviral agent.

Antiviral Agents↗
PubMed1996

Miscoding properties of isoguanine (2-oxoadenine) studied in an AMV reverse transcriptase in vitro system.

We have found that isoguanine (iG) can pair with thymine (iG.T) and the non-natural base, 5-methylisocytosine (iG.iCM) during template directed synthesis catalyzed by AMV reverse transcriptase. The ratio of these pairings is about 1:10, irrespectively which of the templates, poly(C,iG) or poly(I,iG) is used. This ratio corresponds to the ratio of 2-OH and 2-keto tautomers in monomer in aqueous solution and apparently it is not influenced by the template context. Our results indicate also that formation of the reverse transcriptase catalyzed base pairs between iG and A, G or C can occur only at a low frequency, comparable to the frequency, of mismatches of.(ABSTRACT TRUNCATED)

5-Methylcytosine↗
PubMed2003

HIV-1 protease and reverse transcriptase mutation patterns responsible for discordances between genotypic drug resistance interpretation algorithms.

Several rules-based algorithms have been developed to interpret results of HIV-1 genotypic resistance tests. To assess the concordance of these algorithms and to identify sequences causing interalgorithm discordances, we applied four publicly available algorithms to the sequences of isolates from 2,045 individuals in northern California. Drug resistance interpretations were classified as S for susceptible, I for intermediate, and R for resistant. Of 30,675 interpretations (2,045 sequences x 15 drugs), 4.4% were completely discordant, with at least one algorithm assigning an S and another an R; 29.2% were partially discordant, with at least one algorithm assigning an S and another an I, or at least one algorithm assigning an I and another an R; and 66.4% displayed complete concordance, with all four algorithms assigning the same interpretation. Discordances between nucleoside reverse transcriptase inhibitor interpretations usually resulted from several simple, frequently occurring mutational patterns. Discordances between protease inhibitor interpretations resulted from a larger number of more complex mutation patterns. Discordances between nonnucleoside reverse transcriptase inhibitor interpretations were uncommon and resulted from a small number of individual drug resistance mutations. Determining the clinical significance of these mutation patterns responsible for interalgorithm discordances will improve interalgorithm concordance and the accuracy of genotypic resistance interpretation.

Algorithms↗
PubMed2003

Sequence characterization of the protease and partial reverse transcriptase proteins of the NED panel, an international HIV type 1 subtype reference and standards panel.

The NED panel (NIH-ENVA-DOD) was assembled by the Virology Quality Assurance Laboratory for use as an international HIV-1 subtype reference and standards panel. The panel contains 44 minimally cultured strains from diverse geographic areas donated by the Walter Reed Army Institute of Research and F. Brun-Vezinet (Hôpital Bichat-Claude Bernard, Paris, France). The contributors assigned the strains to group M subtypes A (5), B (10), C (6), D (3), E (10), F (5), G (2), H (1), and O (2) before donation. Phylogenetic and recombination analyses of the protease gene and a partial sequence of the reverse transcriptase gene of each seed pool indicated potentially three more recombinants in the panel in addition to the two previously recognized recombinants. Alignments of the amino acids to corresponding regions of pNL4-3 showed protease amino acid sequence identity ranged from 68.5 % (group O) to 95.2 % (subtype B). Reverse transcriptase amino acid identity ranged from 84.5% (group O) to 96.8% (clade B). Codons associated with antiretroviral resistance were primarily wild type and highly conserved among all the clades.

Drug Resistance, Viral↗
PubMed1997

Chemical barriers to human immunodeficiency virus type 1 (HIV-1) infection: retrovirucidal activity of UC781, a thiocarboxanilide nonnucleoside inhibitor of HIV-1 reverse transcriptase.

UC781, a thiocarboxanilide nonnucleoside inhibitor of human immunodeficiency virus type 1 (HIV-1) reverse transcriptase (RT), inhibited RT DNA polymerase activity in vitro with marked potency. Significant inhibition was noted at a 1:1 molar ratio of UC871 to RT, characteristic of a tight-binding inhibitor. Infectivity of the HIV-1(IIIB) laboratory strain was eliminated in a concentration-dependent manner following short exposure of isolated virion particles to UC781. Neither nevirapine nor certain other carboxanilide nonnucleoside inhibitors were effective in this manner. Endogenous reverse transcription in UC781-treated virus particles was markedly reduced. Treatment of chronically HIV-1-infected H9 cells with UC781 did not alter virus production, but the infectivity of the virus produced by the cells during drug exposure was markedly reduced. Moreover, the infectivity of nascent virus produced by the UC781-treated H9 cells after removal of exogenous drug was dramatically attenuated. Similarly, pretreatment of peripheral blood lymphocytes isolated from HIV-infected patients abolished the infectivity of virus produced by these cells after removal of exogenous drug, as measured by coculture experiments with uninfected cord blood mononuclear cells, indicating the utility of UC781 against a variety of clinical HIV samples. Importantly, preincubation of uninfected MT2 cells with UC781 rendered these cells refractory to subsequent HIV infection in the absence of extracellular drug, an effect that persisted for several days following removal of exogenous drug. These unique properties of UC781 indicate that this nonnucleoside inhibitor may have considerable promise for use in retrovirucidal formulations to minimize the spread of HIV from infected to noninfected individuals.

Anilides↗