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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.

We determine phenotypic susceptibility of human immunodeficiency virus type 2 (HIV-2) isolates to amprenavir, atazanavir, darunavir, indinavir, lopinavir, nelfinavir, saquinavir, and tipranavir. Saquinavir, lopinavir, and darunavir are potent against wild-type HIV-2 isolates and should be preferred as first-line options for HIV-2-infected patients. Other protease inhibitors are less active against HIV-2 than against HIV-1.

Objectives: The sequence variability in the protease and in the 5 Gag cleavage sites (CS) were explored to look for eventual associations between the mutations. Moreover, we have evaluated associations between the Gag region sequence and the virological response to Protease Inhibitors (PI)., Methods: The protease and the 5 Gag CS sequences from 98 PI-experienced patients were sequenced and compared to the HXB2 reference sequence. Sixty patients, treated by Saquinavir plus Ritonavir, were studied to evaluate the clinical impact of the Gag region variability., Results: The relationship between 63 protease mutations and 21 Gag CS mutations were explored. Two patterns of mutations in the protease were identified: (M46I/L, I54V, V82A/T/F) was associated to the A431V and (K20I/R/M, L89M/I) to the S373Q and L449P. None of the Gag CS mutations resulting from PI treatment was associated to the virological response to SQV/r. On the other hand, the S373P mutation had a negative impact on the virological response that remained statistically significant in a multivariate analysis after adjustment on the number of PI resistance mutations., Conclusions: These results evoke the pertinence to introduce some mutations found in the Gag CS in the algorithms used for the interpretation of resistance testing.

Objective: To identify a genotypic score for resistance to saquinavir boosted with ritonavir (SQV/r; 1,000/100 mg twice daily)-based regimens in protease inhibitor (PI)-experienced patients., Methods: One-hundred and fifty-one PI-experienced patients receiving a SOV/r-containing regimen were enrolled retrospectively. The virological response (VR) was defined as the decrease in HIV RNA at months 3-5. The effect of each mutation in the protease gene on the VR to SQV/r regimen was assessed using non-parametric univariate analyses and then a step-by-step analysis was carried out using a Jonckheere-Tepstra (JT) nonparametric test to retain the group of mutations most strongly associated with VR., Results: Among the 138 patients with detectable plasma SQV, the median VR was -1.48 [range: -4 to +1.2] log10 copies/ml. Changes at 12 codons were associated with a reduced VR to SQV/r: codons 10, 15, 20, 24, 46, 54, 62, 71, 73, 82, 84 and 90. The JT procedure led to selection of the following genotypic score, 10+15+20+ 24+62+73+82+84+90, as providing the strongest association with VR. In the 35 patients with none of the mutations in this score, the median decrease in HIV RNA was -2.24 log10 copies/ml and it was -1.88 (n=29), -1.43 (n=24), -0.52 (n=30), -0.18 (n=9), -0.11 (n=6) and -0.30 (n=5) log10 copies/ml in those with 1, 2, 3, 4, 5 and 6 mutations, respectively., Conclusion: With this resistance score to SQV/r, the isolates were classified as having no evidence of resistance (0-2), possible resistance (3) or resistance (> or =4) by grouping the number of mutations in samples for which the viral load reduction was similar.

We investigated, in the protease and GAG cleavage sites, the role of minority populations on the evolution of resistance to a subsequent boosted protease inhibitor (PI) regimen after a first failure to nelfinavir. Two pathways were observed: the addition of mutations to a currently dominant genotype when minority variants are not shown, or the emergence of a minority variant as a dominant strain. These minor species, not detected by standard genotype, may influence PI susceptibility.