The objective of this study is to evaluate the safety and efficacy of a regimen containing cobicistat-boosted atazanavir (ATV+COBI) plus emtricitabine/tenofovir disoproxil fumarate (Truvada®; FTC/TDF) versus ritonavir-boosted atazanavir (ATV+RTV) plus FTC/TDF in HIV-1 infected, antiretroviral treatment-naive adults.

Participants will be randomized in a 2:1 ratio. Randomization will be stratified by HIV-1 RNA level (≤ 100,000 copies/mL or > 100,000 copies/mL) at screening. After Week 48, participants will continue to take their blinded study drug and attend visits every 12 weeks until treatment assignments are unblinded, at which point all participants will return for an unblinding visit and be given the option to participate in an open-label rollover extension and receive ATV+COBI+FTC/TDF until COBI tablets become commercially available, or until Gilead Sciences elects to terminate the study.

Inclusion Criteria:

• Ability to understand and sign a written informed consent form
• Plasma HIV-1 RNA levels ≥ 5,000 copies/mL
• No prior use of any approved or experimental anti-HIV drug
• Normal ECG (or if abnormal, determined by the investigator to be not clinically significant)
• Adequate renal function (estimated glomerular filtration rate ≥ 80 mL/min according to the Cockcroft-Gault formula)
• Hepatic transaminases ≤ 2.5 × upper limit of normal
• Total bilirubin ≤ 1.5 mg/dL, or normal direct bilirubin
• Adequate hematologic function (absolute neutrophil count ≥ 1000/mm^3; platelets ≥ 50,000/mm^3; hemoglobin ≥ 8.5 g/dL)
• Cluster of differentiation 4 (CD4) cell count > 50 cells/µL
• Serum amylase ≤ 1.5 × ULN (subjects with serum amylase >1.5 × ULN remained eligible if serum lipase is ≤ 1.5 × ULN)
• Normal thyroid-stimulating hormone
• Negative serum pregnancy test (females of childbearing potential only)
• Males and females of childbearing potential must agree to utilize highly effective contraception methods from screening throughout the duration of study treatment and for 30 days following the last dose of study drugs
• Age ≥ 18 years
• Life expectancy ≥ 1 year

Exclusion Criteria:

• New AIDS-defining condition diagnosed within the 30 days prior to screening
• Documented drug resistance to nucleoside or nucleotide reverse transcriptase inhibitors (NRTIs), nonnucleoside reverse transcriptase inhibitors (NNRTIs), or primary PI resistance mutation(s)
• Hepatitis B surface antigen positive
• Hepatitis C antibody positive
• Participants experiencing cirrhosis
• Participants experiencing ascites
• Participants experiencing encephalopathy
• Females who are breastfeeding
• Positive serum pregnancy test (female of childbearing potential)
• Vaccinated within 90 days of study dosing
• History or family history of Long QT Syndrome or have a family history of sudden cardiac death or unexplained death in an otherwise healthy individual under the age of 30 years
• Presence or history of cardiovascular disease, cardiomyopathy, and/or cardiac conduction abnormalities
• Prolonged QTcF (QT interval corrected for heart rate using Fridericia's formula) interval at screening (eg, a prolongation of the QTcF interval of greater than 450 msec for males and greater than 470 msec for females)
• PR interval greater than or equal to 200 msec or less than or equal to 120 msec on ECG at screening
• QRS greater than or equal to 120 msec on ECG at screening
• Implanted defibrillator or pacemaker
• Subjects receiving ongoing therapy with any disallowed medications
• Current alcohol or substance use judged to potentially interfere with subject study compliance
• History of or ongoing malignancy (including untreated carcinoma in-situ) other than cutaneous Kaposi's sarcoma, basal cell carcinoma, or resected, noninvasive cutaneous squamous carcinoma
• Active, serious infections (other than HIV-1 infection) requiring parenteral antibiotic or antifungal therapy within 30 days prior to baseline
• Participation in any other clinical trial without prior approval
• Medications contraindicated for use with ATV, RTV, FTC, or TDF
• Any known allergies to the excipients of ATV capsules, RTV capsules, COBI tablets or FTC/TDF tablets
• Any other clinical condition or prior therapy that would make the subject unsuitable for the study or unable to comply with the dosing requirements

After conclusion of the study and without prior written approval from Gilead, investigators in this study may communicate, orally present, or publish in scientific journals or other media only after the following conditions have been met:

• The results of the study in their entirety have been publicly disclosed by or with the consent of Gilead in an abstract, manuscript, or presentation form; or
• The study has been completed at all study sites for at least 2 years