Loss of protease dimerization inhibition activity of darunavir is associated with the acquisition of resistance to darunavir by HIV-1

J Virol. 2011 Oct;85(19):10079-89. doi: 10.1128/JVI.05121-11. Epub 2011 Aug 3.


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 (FRET)-based HIV expression assay. All recombinant HIV(NL4-3)-based clones with such a protease dimerization-disrupting substitution failed to replicate. A highly DRV-resistant in vitro-selected HIV variant and clinical HIV strains isolated from AIDS patients failing to respond to DRV-containing antiviral regimens typically had the V32I, L33F, I54M, and I84V substitutions in common in protease. None of up to 3 of the 4 substitutions affected DRV's protease dimerization inhibition, which was significantly compromised by the four combined substitutions. Recombinant infectious clones containing up to 3 of the 4 substitutions remained sensitive to DRV, while a clonal HIV variant with all 4 substitutions proved highly resistant to DRV with a 205-fold 50% effective concentration (EC(50)) difference compared to HIV(NL4-3). The present data suggest that the loss of DRV activity to inhibit protease dimerization represents a novel mechanism contributing to HIV resistance to DRV. The finding that 4 substitutions in PR are required for significant loss of DRV's protease dimerization inhibition should at least partially explain the reason DRV has a high genetic barrier against HIV's acquisition of DRV resistance.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, N.I.H., Intramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Amino Acid Substitution / genetics
  • Anti-HIV Agents / metabolism*
  • Cell Line
  • DNA Mutational Analysis
  • Darunavir
  • Drug Resistance, Viral*
  • Fluorescence Resonance Energy Transfer
  • HIV Protease / genetics
  • HIV Protease / metabolism*
  • HIV-1 / drug effects*
  • HIV-1 / physiology
  • Humans
  • Mutant Proteins / genetics
  • Mutant Proteins / metabolism
  • Protein Multimerization / drug effects*
  • Sulfonamides / metabolism*
  • Virus Replication / drug effects*


  • Anti-HIV Agents
  • Mutant Proteins
  • Sulfonamides
  • HIV Protease
  • p16 protease, Human immunodeficiency virus 1
  • Darunavir