This is a single-center drug distribution and pharmacokinetic study of a single microdose of 18F-raltegravir given to 10 HIV-infected subjects who are either taking or not taking a raltegravir-containing ART regimen. After administration of IV 18F-raltegravir, subjects will undergo PET/MRI in order to determine the distribution of radiolabeled drug through the lymphoreticular system and other tissues throughout the entire body.

Inclusion Criteria:

• Age ≥18 years
• HIV infection
• Initiated a combination ART (HAART) regimen

Exclusion Criteria:

• Screening absolute neutrophil count <1,000 cells/mm3, platelet count <70,000 cells/mm3, hemoglobin < 8 mg/dL, estimated creatinine clearance <40 mL/minute, aspartate aminotransferase >100 units/L, alanine aminotransferase >100 units/L.
• Serious illness requiring hospitalization or parental antibiotics within the preceding 3 months.
• Any vaccination 2 weeks prior to baseline (Day 0) visit and throughout the study period.
• Concurrent treatment with immunomodulatory drugs, or exposure to any immunomodulatory drug in the preceding 16 weeks (e.g. corticosteroid therapy equal to or exceeding a dose of 15 mg/day of prednisone for more than 10 days, IL-2, interferon-alpha, methotrexate, cancer chemotherapy). NOTE: Use of inhaled or nasal steroid use is not exclusionary.
• Pregnant or breastfeeding women. Females of childbearing potential must have a negative serum pregnancy test at screening and agree to use a double-barrier method of contraception throughout the study period.
• Have a cardiac pacemaker or other indwelling foreign object that are contraindicated for MR imaging.