A common mechanism of clinical HIV-1 resistance to the CCR5 antagonist maraviroc despite divergent resistance levels and lack of common gp120 resistance mutations

Michael Roche,Benhur Lee,Anne Ellett,Helena Zappi,Paul R Gorry,Mike Westby,Kelechi Chikere,Becky Jubb,Jasminka Sterjovski,Nicholas E Webb ,Paul A Ramsland ,Lachlan Robert Gray ,Miranda S Moore ,Brendan L Wilkinson ,Richard J Payne ,Melissa Churchill ,Robert J Duncan ,Jacqueline K Flynn ,Sharon R Lewin ,Hamid Salehiniya

doi:10.1186/1742-4690-10-43

Abstract

BackgroundThe CCR5 antagonist maraviroc (MVC) inhibits human immunodeficiency virus type 1 (HIV-1) entry by altering the CCR5 extracellular loops (ECL), such that the gp120 envelope glycoproteins (Env) no longer recognize CCR5. The mechanisms of HIV-1 resistance to MVC, the only CCR5 antagonist licensed for clinical use are poorly understood, with insights into MVC resistance almost exclusively limited to knowledge obtained from in vitro studies or from studies of resistance to other CCR5 antagonists. To more precisely understand mechanisms of resistance to MVC in vivo, we characterized Envs isolated from 2 subjects who experienced virologic failure on MVC.ResultsEnvs were cloned from subjects 17 and 24 before commencement of MVC (17-Sens and 24-Sens) and after virologic failure (17-Res and 24-Res). The Envs cloned during virologic failure showed broad divergence in resistance levels, with 17-Res Env exhibiting a relatively high maximal percent inhibition (MPI) of ~90% in NP2-CD4/CCR5 cells and peripheral blood mononuclear cells (PBMC), and 24-Res Env exhibiting a very low MPI of ~0 to 12% in both cell types, indicating relatively “weak” and “strong” resistance, respectively. Resistance mutations were strain-specific and mapped to the gp120 V3 loop. Affinity profiling by the 293-Affinofile assay and mathematical modeling using VERSA (Viral Entry Receptor Sensitivity Analysis) metrics revealed that 17-Res and 24-Res Envs engaged MVC-bound CCR5 inefficiently or very efficiently, respectively. Despite highly divergent phenotypes, and a lack of common gp120 resistance mutations, both resistant Envs exhibited an almost superimposable pattern of dramatically increased reliance on sulfated tyrosine residues in the CCR5 N-terminus, and on histidine residues in the CCR5 ECLs. This altered mechanism of CCR5 engagement rendered both the resistant Envs susceptible to neutralization by a sulfated peptide fragment of the CCR5 N-terminus.ConclusionsClinical resistance to MVC may involve divergent Env phenotypes and different genetic alterations in gp120, but the molecular mechanism of resistance of the Envs studied here appears to be related. The increased reliance on sulfated CCR5 N-terminus residues suggests a new avenue to block HIV-1 entry by CCR5 N-terminus sulfopeptidomimetic drugs.

Highlights

The CCR5 antagonist maraviroc (MVC) inhibits human immunodeficiency virus type 1 (HIV-1) entry by altering the CCR5 extracellular loops (ECL), such that the gp120 envelope glycoproteins (Env) no longer recognize CCR5
Characteristics of the MVC sensitive and MVC resistant Env clones Our previous studies revealed the molecular mechanisms responsible for the recognition of the MVCmodified form of CCR5 by a MVC-resistant Env that was derived in vitro [51]. To determine how these mechanisms relate to those occurring in vivo, we obtained HIV-1 Envs derived from two subjects who commenced MVC treatment along with optimized background therapy as part of the MOTIVATE phase III clinical trial, and who experienced virologic failure associated with phenotypically-verified MVC resistance [47,52,56,57]
In the presence of MVC, 17Res and 24-Res Envs both became critically reliant on His88 and His181 in the CCR5 ECL1 and ECL2 regions, respectively, which is similar to the pattern of increased reliance on these residues that we have reported for a MVC-resistant strain that was generated in vitro [51]. 17-Res Env adopted an increased reliance on Tyr184 and Phe264 in the CCR5 ECL2 and ECL3 regions, respectively, whereas 24-Res Env did not

Summary

Introduction

The CCR5 antagonist maraviroc (MVC) inhibits human immunodeficiency virus type 1 (HIV-1) entry by altering the CCR5 extracellular loops (ECL), such that the gp120 envelope glycoproteins (Env) no longer recognize CCR5. Human immunodeficiency virus type 1 (HIV-1) entry into cells is mediated by the viral envelope glycoproteins (Env) that decorate the surface of the virion (reviewed in [1,2]). The primary point of contact between Env and the host cell is between gp120 and cellular CD4 This leads to structural rearrangements in gp120 that expose the binding site for a cellular coreceptor, which is either of the chemokine receptors CCR5 or CXCR4. Extending from the helices are the chemokine binding domains, comprising the N-terminus and three extracellular loops (ECL1, 2 and 3). Sulfation of tyrosine residues in the CCR5 N-terminus, those at position 10 and 14, has been shown to be important for HIV-1 entry [7,8]

Methods

Results

Conclusion