Loss of Protease Dimerization Inhibition Activity of Darunavir Is Associated with the Acquisition of Resistance to Darunavir by HIV-1

Abstract

Dimerization of HIV protease is essential for the acquisition of protease's proteolytic activity. We previously identified a group of HIV protease dimerization inhibitors, including darunavir (DRV). In the present work, we examine whether loss of DRV's protease dimerization inhibition activity is associated with HIV development of DRV resistance. Single amino acid substitutions, including I3A, L5A, R8A/Q, L24A, T26A, D29N, R87K, T96A, L97A, and F99A, disrupted protease dimerization, as examined using an intermolecular fluorescence resonance energy transfer (

Loss of the Protease Dimerization Inhibition Activity of Tipranavir (TPV) and Its Association with the Acquisition of Resistance to TPV by HIV-1

“…These data together should explain why the genetic barrier of TPV against viral resistance is substantially lower than that of DRV. The present data on TPV as well as thus far published data on DRV (20,21) demonstrate that the inhibition of protease dimerization contributes to the overall anti-HIV-1 activity of TPV and DRV, and it is hoped that agents with further potent activity to block protease dimerization can be developed. …”

“…Importantly, TPV's activity to block protease dimerization is compromised mostly with a single amino acid substitution, while the loss of DRV's ability to block protease dimerization requires as many as 4 amino acid substitutions (20). In addition, the activity of TPV to block protease dimerization per se is significantly less potent than that of DRV.…”

“…However, various amino acid substitutions that are potentially related to HIV-1 resistance to DRV have been reported (7,19,20,27,38). We have recently demonstrated, using the FRET-based HIV-1 expression assay, that the loss of DRV activity to inhibit protease dimerization requires at least four combined amino acid substitutions in protease and that the loss of DRV's protease dimerization inhibition activity is associated with HIV-1 acquisition of DRV resistance (20). In the present work, we specifically asked whether TPV's protease dimerization inhibition activity contributes to the antiretroviral activity of TPV against a series of multi-PI-resistant HIV-1 variants and whether the loss of such protease dimerization inhibition activity of TPV is associated with the development of HIV-1 resistance to TPV.…”

“…Using this assay, we have recently identified a group of nonpeptidyl small-molecule inhibitors of HIV-1 PR dimerization, including TPV, darunavir (DRV), and a series of experimental antiretroviral agents (21). DRV (12,13,22) potently inhibits the enzymatic activity and dimerization of HIV-1 PR (20,21), and a high genetic barrier against HIV-1 development of DRV resistance exists (7,8). However, various amino acid substitutions that are potentially related to HIV-1 resistance to DRV have been reported (7,19,20,27,38).…”

“…DRV (12,13,22) potently inhibits the enzymatic activity and dimerization of HIV-1 PR (20,21), and a high genetic barrier against HIV-1 development of DRV resistance exists (7,8). However, various amino acid substitutions that are potentially related to HIV-1 resistance to DRV have been reported (7,19,20,27,38). We have recently demonstrated, using the FRET-based HIV-1 expression assay, that the loss of DRV activity to inhibit protease dimerization requires at least four combined amino acid substitutions in protease and that the loss of DRV's protease dimerization inhibition activity is associated with HIV-1 acquisition of DRV resistance (20).…”