Emergence Of Drug-resistant HIV-1 Variants Research Articles

A novel central nervous system-penetrating protease inhibitor overcomes human immunodeficiency virus 1 resistance with unprecedented aM to pM potency.

Antiretroviral therapy for HIV-1 infection/AIDS has significantly extended the life expectancy of HIV-1-infected individuals and reduced HIV-1 transmission at very high rates. However, certain individuals who initially achieve viral suppression to undetectable levels may eventually suffer treatment failure mainly due to adverse effects and the emergence of drug-resistant HIV-1 variants. Here, we report GRL-142, a novel HIV-1 protease inhibitor containing an unprecedented 6-5-5-ring-fused crown-like tetrahydropyranofuran, which has extremely potent activity against all HIV-1 strains examined with IC50 values of attomolar-to-picomolar concentrations, virtually no effects on cellular growth, extremely high genetic barrier against the emergence of drug-resistant variants, and favorable intracellular and central nervous system penetration. GRL-142 forms optimum polar, van der Waals, and halogen bond interactions with HIV-1 protease and strongly blocks protease dimerization, demonstrating that combined multiple optimizing elements significantly enhance molecular and atomic interactions with a target protein and generate unprecedentedly potent and practically favorable agents.

ChemInform Abstract: Enhancing Protein Backbone Binding — A Fruitful Concept for Combating Drug‐Resistant HIV.

AbstractReview: 137 refs.

2′-Deoxy-4′-C-Ethynyl-2-Fluoroadenosine: A Nucleoside Reverse Transcriptase Inhibitor with Highly Potent Activity Against Wide Spectrum of HIV-1 Strains, Favorable Toxic Profiles, and Stability in Plasma

Working hypotheses to solve the critical problems of the existing highly active anti-retroviral therapy were proposed. The study based on the hypotheses proved the validity of the hypotheses and resulted in the development of 2′-deoxy-4′-C-ethynyl-2-fluoroadenosine, a nucleoside reverse transcriptase inhibitor, with highly potent activity against all HIV-1, very favorable toxic profiles, and stability in plasma. The nucleoside will prevent or delay the emergence of drug-resistant HIV-1 variants and be an ideal therapeutic agent for both HIV-1 and HBV infections.

A sensitive genotyping assay for detection of drug resistance mutations in reverse transcriptase of HIV-1 subtypes B and C in samples stored as dried blood spots or frozen RNA extracts

Exposure to antiretroviral drugs in resource-constrained settings is likely to result in the emergence of drug-resistant HIV-1 variants, limiting treatment options. Genotypic drug resistance testing assists clinical management and outcomes assessment, but a sensitive and reproducible genotypic assay feasible for resource-constrained settings is needed. A sensitive, reproducible genotyping assay to detect HIV-1 drug resistance mutations in reverse transcriptase and protease was developed and validated using blood stored as dried blood spots or as frozen RNA extracts from Zambian children infected with subtype C. HIV-1 genotypes derived from samples stored as dried blood spots were compared to those derived from paired liquid plasma samples in American young adults infected with HIV-1 subtype B. The method reproducibly amplified patient-specific sequences and detected drug resistance mutations from all of the dried blood spots or excess frozen RNA extracts with detectable viremia over a broad range of viral loads (193–3 million HIV-1 RNA copies/mL) in both HIV-1 subtypes B and C infection. This method captured the genetic variation typical of HIV-1 infection, including mutations at usual sites of drug resistance, polymorphisms, and mixtures. This sensitive and reproducible genotypic assay is feasible for detection of antiretroviral resistance in resource-constrained settings.

Computational Simulations of HIV-1 ProteasesMulti-drug Resistance Due to Nonactive Site Mutation L90M

Human immunodeficiency virus type 1 protease (HIV-1 PR) is one of the proteins that currently available anti-HIV-1 drugs target. Inhibitors of HIV-1 PR have become available, and they have lowered the rate of mortality from acquired immune deficiency syndrome (AIDS) in advanced countries. However, the rate of emergence of drug-resistant HIV-1 variants is quite high because of their short retroviral life cycle and their high mutation rate. Serious drug-resistant mutations against HIV-1 PR inhibitors (PIs) frequently appear at the active site of PR. Exceptionally, some other mutations such as L90M cause drug resistance, although these appear at nonactive sites. The mechanism of resistance due to nonactive site mutations is difficult to explain. In this study, we carried out computational simulations of L90M PR in complex with each of three kinds of inhibitors and one typical substrate, and we clarified the mechanism of resistance. The L90M mutation causes changes in interaction between the side chain atoms of the 90th residue and the main chain atoms of the 25th residue, and a slight dislocation of the 25th residue causes rotation of the side chain at the 84th residue. The rotation of the 84th residue leads to displacement of the inhibitor from the appropriate binding location, resulting in a collision with the flap or loop region. The difference in levels of resistance to the three inhibitors has been explained from energetic and structural viewpoints, which provides the suggestion for promising drugs keeping its efficacy even for the L90M mutant.

In vitro suppression of latent HIV-1 activation by vitamin E: potential clinical implications

We evaluated the effect of vitamin E in controlling HIV-1 production upon activation of the patients' reservoir of resting CD4 lymphocytes in tissue culture experiments. The addition of vitamin E to patients' cultures resulted in significantly reduced levels of p24 virus production (P = 0.0015). These results suggest that vitamin E supplementation may interfere with the emergence of drug-resistant HIV-1 variants archived in the resting cell reservoir and delay or limit virus rebound upon treatment interruptions.

Emergence of a Drug-Dependent Human Immunodeficiency Virus Type 1 Variant during Therapy with the T20 Fusion Inhibitor

The fusion inhibitor T20 belongs to a new class of anti-human immunodeficiency virus type 1 (HIV-1) drugs designed to block entry of the virus into the host cell. However, the success of T20 has met with the inevitable emergence of drug-resistant HIV-1 variants. We describe an evolutionary pathway taken by HIV-1 to escape from the selective pressure of T20 in a treated patient. Besides the appearance of T20-resistant variants, we report for the first time the emergence of drug-dependent viruses with mutations in both the HR1 and HR2 domains of envelope glycoprotein 41. We propose a mechanistic model for the dependence of HIV-1 entry on the T20 peptide. The T20-dependent mutant is more prone to undergo the conformational switch that results in the formation of the fusogenic six-helix bundle structure in gp41. A premature switch will generate nonfunctional envelope glycoproteins (dead spikes) on the surface of the virion, and T20 prevents this abortive event by acting as a safety pin that preserves an earlier prefusion conformation.

Emergence of drug-resistant HIV-1 variants in patients undergoing structured treatment interruptions.

We report the emergence of drug-resistant viral mutations in chronically HIV-infected individual undergoing structured treatment interruptions (STI). THe protease mutations K101E and K103N were detected at the end of the second or third STI. We concluded that the repeated abrupt termination and resumption of certain antiretroviral drug regimens during STI therapy may lead to the development of drug resistance in chronically HIV-infected individuals.

Evaluation of human immunodeficiency virus (HIV) type 1 RNA levels in cerebrospinal fluid and viral resistance to zidovudine in children with HIV encephalopathy.

The amount of human immunodeficiency virus (HIV) type 1 RNA and the presence of a codon 215 mutation indicative of zidovudine resistance were evaluated in cerebrospinal fluid (CSF) and plasma obtained from HIV-1-infected children. The level of HIV-1 RNA in CSF was highest in children with severe encephalopathy (n = 25; median, 430 copies/mL; range, 0-2.2 x 10(5) copies/mL) followed by the moderately encephalopathic (n = 7; median, 330; range, 0-1130) and nonencephalopathic groups (n = 9; median, 0; range, 0-566) (P = .007). There was no correlation between CSF and plasma HIV-1 RNA levels. Five of 7 children with the codon 215 mutation in CSF had a progression of encephalopathy, while all 8 children with wild type codon 215 had improved or stable disease during zidovudine treatment (P = .007). These findings suggest that increased viral replication and emergence of drug-resistant HIV-1 variants within the central nervous system may play a role in progression of HIV encephalopathy.

Quantitative analysis of the endogenous reverse transcriptase reactions of HIV type 1 variants with decreased susceptibility to azidothymidine and nevirapine.

A large number of nucleoside analog and nonnucleoside inhibitors of HIV-1 reverse transcriptase (RT) have been developed for clinical use. Data confirm that resistant variants of HIV-1 rapidly emerge in response to the selective pressure of treatment with these agents. Detection of drug resistance generally involves detection of specific mutations in the viral genome or demonstrating a failure of the drug to suppress virus replication in culture. We have developed a PCR-based method to quantitatively examine HIV-1 DNA synthesis in vitro in endogenous reverse transcription reactions and tested it as a method to detect resistance to RT inhibitors. Under certain conditions, we were able to distinguish HIV strains with high-level resistance to azidothymidine triphosphate inhibition from sensitive strains. This method was quite useful as an assay to detect resistance to nevirapine, a nonnucleoside RT inhibitor; in reconstruction experiments, nevirapine-resistant virus was detectable when it represented 10 to 25% of the total amount of virus present in reaction mixtures. These data are examined in the light of current models of the mechanisms of action of nucleoside nonnucleoside RT inhibitors. This assay may be useful for detecting the emergence of drug-resistant HIV-1 variants during therapy.