Impact of HIV-1 replication on immunological evolution during long-term dual-boosted protease inhibitor therapy.

To explore CD4-cell and viral evolution in relation to different levels of HIV-1 replication, as observed during protease inhibitor (PI)-based antiretroviral therapy. Adult HIV-1 infected cohort patients, receiving historical salvage therapy with daily doses of saquinavir (2,000 mg), ritonavir (200 mg) and either lopinavir (800 mg) or atazanavir (300 mg) for >36 weeks were retrospectively analysed for highest detectable viral load up to week 96 and assigned to groups according to the viral load level: always 200 copies/ml was associated with decreasing CD4-cell slopes and emergence of major mutations, supporting this as benchmark for virological failure definition on PI therapy.