The HIV type 1 protease L10I minor mutation decreases replication capacity and confers resistance to protease inhibitors.

The effect of minor mutations in PR on treatment outcome has not been well established. We characterized the HIV protease minor mutations, L10I, compared to the minor mutation, L63P, and the major mutation D30N and their impact on viral fitness and resistance to protease inhibitors. Mutations were introduced individually and in combination by site-directed mutagenesis into the provirus pNL4.3ren and constructs used for replication capacity (RC) and resistance assays. A structure prediction of the protease carrying the L10I mutation was determined. The prevalence of the minor mutation L10I had a pattern similar to that found for major mutations D30N, with a low prevalence (4.9%) in naive patients and significantly higher prevalence in treated patients. Furthermore, viruses carrying the major mutation D30N or the minor mutation L10I showed a significant decrease in RC (p-value <0.05), whereas viruses carrying the minor mutation L63P had RC similar to wild-type virus. In addition, the L10I mutation conferred resistance to saquinavir, which was supported by the higher prevalence in the cohort of the L10I mutation among patients with SQV resistance. The molecular modeling suggests that L10I may affect the conformation of Leu-23, a critical residue in the substrate binding site. In conclusion, the L10I mutation impairs RC and confers resistance to SQV, similarly to other major mutations, which may be related with changes in the conformation in the protease binding site. The presence of this mutation in the genotype of HIV from patients should be taken into consideration when designing new optimize treatments.