This randomized, single-center, open-label, one-sequence, two-period crossover study in three parts will assess the effects of multiple doses of ketoconazole, rifampicin and ritonavir-boosted atazanavir on the pharmacokinetics of a single dose of RO5093151 in healthy male and female volunteers. In Period 1, subjects will receive a single oral dose of RO5093151. In Period 2, subjects will receive a single oral dose of RO5093151 and multiple oral doses of either ketoconazole, rifampicin or ritonavir-boosted atazanavir. Anticipated time on study is up to 8.5 weeks.

Inclusion Criteria:

• Healthy male and female subjects, 18 to 65 years of age. Healthy status is defined by absence of evidence of any active or chronic disease following a detailed medical and surgical history and complete physical examination
• Body mass index (BMI) 18 to 30 kg/m2
• Females of child-bearing potential must agree to use two effective methods of contraception, including a barrier method and an intrauterine non-hormonal device (set in place at least 3 months before first dosing) for the duration of the study and at least 1 month after last dosing
• Non-smoker for at least 90 days prior to screening

Exclusion Criteria:

• Pregnant or lactating females
• History of drug abuse in the past 2 years, or suspicion of regular consumption of drugs of abuse, or positive result on drugs of abuse test
• History of alcoholism in the past 2 years, or positive alcohol test
• Positive for hepatitis B, hepatitis C or HIV infection
• Systemic , topical, intranasal or inhaled corticosteroid therapy for more than 2 weeks within 3 months prior to screening
• Participation in an investigational drug or device study within 90 days prior to screening