Lopinavir/ritonavir resistance in patients infected with HIV-1: two divergent resistance pathways?

The HIV-1 protease L76V mutation has been described recently as conferring high-level resistance to lopinavir/ritonavir (LPV/r). The aim was to identify the factors and particularly protease mutations associated with the presence of L76V in treatment-experienced patients infected with HIV-1 who have failed virologically an LPV/r-based antiretroviral therapy regimen. This is a retrospective exploratory study. Patients were eligible if they were in care at the Northern France AIDS reference center between 2000 and 2009, failed virologically an LPV/r-based regimen, and infected with HIV-1 strains carrying LPV/r-resistant mutations (genotype resistance test after failure). Multivariate logistic regressions were used to compare LPV/r-resistant patients infected with virus harboring the L76V mutation or not (L76V positive/L76V negative). Twelve patients with virus L76V positive were identified and compared to 24 patients with virus L76V negative selected at random. Demographic and clinical data were not different significantly between the two groups. In univariate analyses, of the mutations found in ≥10% of patients, L89M and Q58E were more prevalent in viruses L76V positive than L76V negative (L89M, 42% vs. 0%, P = 0.0007; Q58E, 50% vs. 25%, P = 0.1). In contrast, I54V, G73S and L90M were less prevalent in viruses L76V positive than L76V negative (I54V, 42% vs. 83%, P = 0.01; G73S, 0% vs. 33%, P = 0.02; L90M, 25% vs. 83%, P = 0.0006). L90M, I54V and Q58E were associated with L76V in a multivariate analysis (P < 0.0001, P = 0.002, and P = 0.008, respectively). These results suggest two divergent pathways leading to LPV/r resistance. One contains the L76V and Q58E mutations and the other contains the L90M and I54V mutations.