The primary objective of the trial is to assess the ability of an early and intermittent antiretroviral therapy in maintaining an immunological stability in antiretroviral naive HIV infected adults, to offer a potential alternative strategy to differed and continuous antiretroviral treatment.This is a 2-year phase II, open-label, multicentric "proof of concept" trial. The patients included are treated following a pulse-therapy scheme, i.e. 6-month periods with once daily boosted-PI based therapy in alternance with 6-month periods without antiretroviral therapy. The preferentially recommended treatment of the study is atazanavir boosted with ritonavir, associated with a fixed combination of abacavir and lamivudine or emtricitabine + tenofovir.The patients are closely followed to assess the efficacy and the tolerance of the strategy, with clinical, biochemical, immunological, virological and pharmacokinetic evaluations.

Inclusion Criteria:

• adult confirmed HIV-1 infection
• no previous treatment with antiretroviral drugs or interleukin-2
• CD4 count ≥ 500/mm3
• no active opportunistic infection
• written informed consent

Exclusion Criteria:

• non barrier contraception in women of child bearing potential, pregnant or breastfeeding woman, pregnancy project within the next 2 years
• HIV-2 infection (with or without HIV-1), recent HIV primary infection, resistance to trial drugs at study entry, Ag HBs+, HCV requiring specific therapy
• previous history of cerebrovascular accident or coronary heart disease, splenectomy
• previous CD4 count < 400/mm3
• CD4 percentage < 15%
• hemoglobin < 8 g/dl, neutrophils < 750/mm3, platelets < 100.000/mm3, creatinine clearance < 50 ml/mn, AST or ALT or total bilirubin > 3 ULN