Mutations associated with virological response to darunavir/ritonavir in HIV-1-infected protease inhibitor-experienced patients

J Antimicrob Chemother. 2009 Mar;63(3):585-92. doi: 10.1093/jac/dkn544. Epub 2009 Jan 15.


Objective: The aim of the study was to identify a pattern of protease gene mutations associated with the virological response to darunavir/ritonavir-based regimens.

Patients and methods: We analysed 153 treatment-experienced patients receiving a darunavir/ritonavir salvage regimen as a sole protease inhibitor (PI). Virological response was defined as an HIV-1 RNA load of <200 copies/mL at month 3. The impact of individual protease gene mutations on the virological response to darunavir/ritonavir was examined, and the combination of mutations most strongly associated with the virological response was identified.

Results: The baseline median HIV RNA level was 4.7 log(10) copies/mL and the median CD4 cell count was 142 cells/mm(3). At month 3, 55% of patients had a virological response and the median fall in viral load from baseline was 1.7 log(10) copies/mL. All the patients had detectable darunavir concentrations at month 3. Cochran-Armitage procedure identified eight mutations with a negative impact on the virological response, namely K14R, K20I, E34Q, I47V, I54M, K55R, T74P and I84V; and two mutations (E35D and V82A) with a positive impact. In multivariate analyses, our genotypic scores were highly predictive of the virological response at month 3, along with the baseline plasma viral load and enfuvirtide co-prescription to enfuvirtide-naive patients.

Conclusions: Among the eight mutations with a negative impact on the virological response, I47V, I54M, T74P and I84V were previously described as darunavir resistance-associated mutations. Some PI resistance mutations had a positive impact on the virological response. These findings might help to explain the potency of darunavir/ritonavir on PI-resistant HIV.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Amino Acid Substitution / genetics
  • CD4 Lymphocyte Count
  • Darunavir
  • Drug Resistance, Viral*
  • Female
  • Genotype
  • HIV Infections / virology
  • HIV Protease / genetics*
  • HIV Protease Inhibitors / therapeutic use*
  • HIV-1 / drug effects
  • HIV-1 / genetics*
  • HIV-1 / isolation & purification
  • Humans
  • Male
  • Mutation, Missense*
  • RNA, Viral / blood
  • Ritonavir / therapeutic use*
  • Sulfonamides / therapeutic use*
  • Treatment Outcome
  • Viral Load


  • HIV Protease Inhibitors
  • RNA, Viral
  • Sulfonamides
  • HIV Protease
  • p16 protease, Human immunodeficiency virus 1
  • Ritonavir
  • Darunavir