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Geno2pheno: Estimating phenotypic drug resistance from HIV-1 genotypes.

ABSTRACT: Therapeutic success of anti-HIV therapies is limited by the development of drug resistant viruses. These genetic variants display complex mutational patterns in their pol gene, which codes for protease and reverse transcriptase, the molecular targets of current antiretroviral therapy. Genotypic resistance testing depends on the ability to interpret such sequence data, whereas phenotypic resistance testing directly measures relative in vitro susceptibility to a drug. From a set of 650 matched genotype-phenotype pairs we construct regression models for the prediction of phenotypic drug resistance from genotypes. Since the range of resistance factors varies considerably between different drugs, two scoring functions are derived from different sets of predicted phenotypes. Firstly, we compare predicted values to those of samples derived from 178 treatment-naive patients and report the relative deviance. Secondly, estimation of the probability density of 2000 predicted phenotypes gives rise to an intrinsic definition of a susceptible and a resistant subpopulation. Thus, for a predicted phenotype, we calculate the probability of membership in the resistant subpopulation. Both scores provide standardized measures of resistance that can be calculated from the genotype and are comparable between drugs. The geno2pheno system makes these genotype interpretations available via the Internet (http://www.genafor.org/).

SUBMITTER: Beerenwinkel N

PROVIDER: S-EPMC168981 | biostudies-literature | 2003 Jul

REPOSITORIES: biostudies-literature

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Geno2pheno: Estimating phenotypic drug resistance from HIV-1 genotypes.

Beerenwinkel Niko N Däumer Martin M Oette Mark M Korn Klaus K Hoffmann Daniel D Kaiser Rolf R Lengauer Thomas T Selbig Joachim J Walter Hauke H

Nucleic acids research 20030701 13

Therapeutic success of anti-HIV therapies is limited by the development of drug resistant viruses. These genetic variants display complex mutational patterns in their pol gene, which codes for protease and reverse transcriptase, the molecular targets of current antiretroviral therapy. Genotypic resistance testing depends on the ability to interpret such sequence data, whereas phenotypic resistance testing directly measures relative in vitro susceptibility to a drug. From a set of 650 matched gen ...[more]

PMID: 12824435

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Project description:BackgroundGenetic variability and liability to develop drug-resistant mutations are the main characteristics of HIV-1, which can not only increase the risk of antiretroviral treatment (ART) failure, but also can lead to the spread of resistant strains. We aim to investigate the distribution of HIV-1 genotypes and prevalence of pretreatment drug resistance (PDR) in ART-naïve HIV-1 infected patients in Shanghai China.MethodsA cross-sectional study was performed among the newly diagnosed ART-naive HIV-1 infected patients during the period from January 2017 to November 2017 in Shanghai Public Health Clinical Center. The target fragment of 1316 bp in the pol gene spanning the reverse transcriptase and protease regions was amplified using a nested polymerase chain reaction. HIV-1 genotypes were determined by phylogenetic analysis, and PDR associated mutations were determined according to Stanford University HIV Drug Resistance Database ( http://hivdb.stanford.edu/ ).ResultsWe successfully amplified pol gene sequences from blood samples of 317 patients, of whom 95.3% were male, and 68.8% were men who have sex with men. The median age was 33 years; and the median CD4 count was 275 cells/μL. The predominant HIV-1 genotype was circulating recombinant form (CRF) 01_AE (53.0%, 168/317), followed by CRF07_BC (29.7%, 94/317), B (7.6%, 24/317), CRF08_BC (1.9%, 6/317), CRF55_01B (1.9%, 6/317), CRF 59_01B (0.9%, 3/317). In addition, 5% (16/317) HIV-1 strains were identified as other subtypes or CRFs/URFs (unique recombinant forms). The overall prevalence of PDR was 17.4% (55/317). PDR frequency to non-nucleoside reverse transcriptase inhibitor (NNRTI, 16.4%) was much higher than that to nucleoside reverse transcriptase inhibitor (NRTI, 4.7%) and protease inhibitor (PI, 0.6%). The most common HIV-1 mutation pattern for NNRTI and NRTI were V179D/E (10.1%, 32/317) and M184 V (2.8%, 9/317), respectively. About half (49.1%, 27/55) of the HIV-1 strains with mutation presented as potential low-level resistant to NNRTI attributed to V179D/E.ConclusionThe distribution of HIV-1 genotypes in Shanghai China is diverse and complex. The high prevalence of PDR highlights the significance of baseline HIV-1 drug resistance testing. Non-NNRTI-containing regimen may be the preferred initial therapy for newly diagnosed HIV-1 patients in Shanghai in the absence of PDR test results.

Project description:Protease inhibitors (PIs) are used as a first-line regimen in HIV-1-infected children. Here we investigated the phenotypic consequences of amino acid changes in Gag and protease on lopinavir (LPV) and ritonavir (RTV) susceptibility among pediatric patients failing PI therapy. The Gag-protease from isolates from 20 HIV-1 subtype C-infected pediatric patients failing an LPV and/or RTV-based regimen was phenotyped using a nonreplicativein vitroassay. Changes in sensitivity to LPV and RTV relative to that of the matched baseline (pretherapy) sample were calculated. Gag and protease amino acid substitutions associated with PI failure were created in a reference clone by site-directed mutagenesis and assessed. Predicted phenotypes were determined using the Stanford drug resistance algorithm. Phenotypic resistance or reduced susceptibility to RTV and/or LPV was observed in isolates from 10 (50%) patients, all of whom had been treated with RTV. In most cases, this was associated with protease resistance mutations, but substitutions at Gag cleavage and noncleavage sites were also detected. Gag amino acid substitutions were also found in isolates from three patients with reduced drug susceptibilities who had wild-type protease. Site-directed mutagenesis confirmed that some amino acid changes in Gag contributed to PI resistance but only in the presence of major protease resistance-associated substitutions. The isolates from all patients who received LPV exclusively were phenotypically susceptible. Baseline isolates from the 20 patients showed a large (47-fold) range in the 50% effective concentration of LPV, which accounted for most of the discordance seen between the experimentally determined and the predicted phenotypes. Overall, the inclusion of thegaggene and the use of matched baseline samples provided a more comprehensive assessment of the effect of PI-induced amino acid changes on PI resistance. The lack of phenotypic resistance to LPV supports the continued use of this drug in pediatric patients.

Dataset Information

Geno2pheno: Estimating phenotypic drug resistance from HIV-1 genotypes.

Publications

Geno2pheno: Estimating phenotypic drug resistance from HIV-1 genotypes.

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