Antiretroviral therapy is complicated by drug interactions and contraindications. Novel regimens are needed.

This open label study randomly assigned treatment-naive, human immunodeficiency virus (HIV)—infected subjects to receive tenofovir-emtricitabine with efavirenz (Arm I), with ritonavir-boosted atazanavir (Arm II), or with zidovudine/abacavir (Arm III). Pair-wise comparisons of differences in time-weighted mean change from baseline plasma HIV-RNA to week 48 formed the primary analysis. Treatment arms were noninferior if the upper limit of the 95% confidence interval (CI) was <0.5 log10 copies/mL. Secondary objectives included virologic, immunologic and safety end points.