A Novel Approach to Assessing the Drug Susceptibility and Replication of Human Immunodeficiency Virus Type 1 Isolates

Monitoring for lamivudine (3TC) resistance is important both for the clinical management of human immunodeficiency virus type 1 (HIV-1)-infected patients treated with 3TC and for surveillance of transmission of 3TC-resistant HIV-1. We developed a novel non-culture-based assay for the rapid analysis of phenotypic resistance to 3TC of HIV-1 in plasma. The assay measures the susceptibility of HIV-1 reverse transcriptase (RT) activity to 3TC triphosphate (3TC-TP) in plasma. RT detection was done by the Amp-RT assay, an ultrasensitive PCR-based RT assay. Under our assay conditions, we found that 5 μM 3TC-TP inhibited RT activity from wild-type (WT), zidovudine-resistant, or nevirapine-resistant HIV-1 but not from HIV-1 carrying either the M184V mutation or multidrug (MD) resistance mutations (77L/116Y/151M or 62V/75I/77L/116Y/151M). Mixing experiments showed a detection threshold of 10% 3TC-resistant virus (M184V) in a background of WT HIV-1. To validate the assay for the detection of phenotypic resistance of HIV-1 to 3TC in plasma samples, HIV-1 RT in 30 plasma specimens collected from 15 patients before and during therapy with 3TC was tested for evidence of phenotypic resistance by the Amp-RT assay. The results were compared with those of genotypic analysis. The RT in 12 samples was found to be 3TC sensitive, while the RT in 18 samples had evidence of phenotypic resistance. All 12 samples with 3TC-sensitive RT had WT genotypes at codon 184 and were retrieved before treatment with 3TC. In contrast, all 18 specimens with 3TC-resistant RT were posttherapy samples. This assay provides a simple, rapid, and reliable method for the detection of phenotypic resistance of HIV-1 to 3TC in plasma.

Section: Discussionsupporting

confidence: 83%

A Rapid Non-Culture-Based Assay for Clinical Monitoring of Phenotypic Resistance of Human Immunodeficiency Virus Type 1 to Lamivudine (3TC)

Lerma

Schinazi

Juodawlkis

et al. 1999

“…The development of the recombinant virus assay (19) and modifications thereof (1,7,12,17) opened the way for rapid, reproducible, and large-scale phenotypic analysis of drug resistance. Phenotypic assays directly measure the ability of HIV to grow in the presence of each drug.…”

Section: Discussionmentioning

confidence: 99%

“…The prolonged virus culture times have also been shown to select for subpopulations of HIV-1 variants (21) which can influence the drug susceptibility profile. Therefore, the description of the recombinant virus assay by Kellam and Larder (19) generated interest in the development of more rapid and reproducible deter-minations of the resistance of HIV to RT inhibitors in clinical samples from HIV-1-infected patients (1,7,12,17). With the introduction of combinations of PR and RT inhibitors in antiretroviral treatment regimens, there was clearly a need to extend phenotypic resistance assays.…”

mentioning

confidence: 99%

A Rapid Method for Simultaneous Detection of Phenotypic Resistance to Inhibitors of Protease and Reverse Transcriptase in Recombinant Human Immunodeficiency Virus Type 1 Isolates from Patients Treated with Antiretroviral Drugs

Hertogs¹,

Béthune²,

Miller

et al. 1998

275

103

Combination therapy with protease (PR) and reverse transcriptase (RT) inhibitors can efficiently suppress human immunodeficiency virus (HIV) replication, but the emergence of drug-resistant variants correlates strongly with therapeutic failure. Here we describe a new method for high-throughput analysis of clinical samples that permits the simultaneous detection of HIV type 1 (HIV-1) phenotypic resistance to both RT and PR inhibitors by means of recombinant virus assay technology. HIV-1 RNA is extracted from plasma samples, and a 2.2-kb fragment containing the entire HIV-1 PR- and RT-coding sequence is amplified by nested reverse transcription-PCR. The pool of PR-RT-coding sequences is then cotransfected into CD4+ T lymphocytes (MT4) with the pGEMT3ΔPRT plasmid from which most of the PR (codons 10 to 99) and RT (codons 1 to 482) sequences are deleted. Homologous recombination leads to the generation of chimeric viruses containing PR- and RT-coding sequences derived from HIV-1 RNA in plasma. The susceptibilities of the chimeric viruses to all currently available RT and/or PR inhibitors is determined by an MT4 cell–3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide-based cell viability assay in an automated system that allows high sample throughput. The profile of resistance to all RT and PR inhibitors is displayed graphically in a single PR-RT-Antivirogram. This assay system facilitates the rapid large-scale phenotypic resistance determinations for all RT and PR inhibitors in one standardized assay.

“…Cell culture sensitivity assay. The ddI susceptibility of the recombinant HIV-1 strains was determined by using MT-2 cells and a colorimetric tetrazolium dye reduction method (12). The test is designed to measure the ability of various ddI concentrations to prevent the killing of MT-2 cells by the virus.…”

Section: Methodsmentioning

confidence: 99%

Human immunodeficiency virus type 1 reverse transcriptase genotype and drug susceptibility changes in infected individuals receiving dideoxyinosine monotherapy for 1 to 2 years

Winters

Shafer

Jellinger

et al. 1997

132

The genetic mechanisms of human immunodeficiency virus type 1 (HIV-1) resistance to dideoxyinosine (ddI) in vivo have been described based on data from primary HIV-1 isolates. To better define the spectrum of HIV-1 reverse transcriptase (RT) changes occurring during ddI therapy, we determined the genotype and ddI susceptibility of the RT gene of HIV RNA isolated from the plasma of 23 patients who had received 1 to 2 years (mean, 87 +/- 16 weeks) of ddI monotherapy. Population-based sequencing of plasma virus showed that 12 of 23 (52%) patients developed known ddI resistance mutations: L74V (7 patients), K65R (2 patients), L74V with M184V (3 patients), and L74V with K65R (1 patient). Five patients developed one or more known zidovudine resistance mutations (at codons 41, 67, 70, 215, and/or 219) during the study. Other amino acid substitutions were found, but only S68G and L210W occurred in more than one patient. Studies of sensitivity to ddI were performed on population-based recombinant-virus stocks generated by homologous recombination between a plasmid containing an HXB2 clone with the RT gene deleted and RT-PCR products of the RT genes from patients' plasma RNA. The sequences of the virus stocks produced by this procedure were typically identical to the sequence of the input PCR product from plasma RNA. Both an MT-2 cell-based culture assay and a cell-free virion-associated RT inhibition assay showed that viruses possessing an L74V and/or M184V mutation or a K65R mutation had reduced sensitivity to ddI. Viruses without these specific mutations had no change in sensitivity to ddI. The results presented here show that the spectrum of RT mutations in a population of patients on ddI monotherapy is more complex than previously described. The development of multiple mutational patterns, including those that confer resistance to other nucleoside analogs, highlights the complexity of using the currently available nucleoside analogs for antiretroviral therapy.