Investigation of V520 in an HIV Vaccine Proof-of-Concept Study (V520-023)

Inclusion Criteria: Healthy, HIV seronegative adults at high risk of acquiring HIV infection Cannot have previously received an investigational vaccine Exclusion Criteria: In a monogamous relationship with an HIV-1 seronegative partner for > 1 year History of anaphylaxis and/or allergy to vaccine components, including Tris buffer, MgCl2, and polysorbate 80 (TWEEN) Received an immune globulin or blood derived products 3 months before injection with the first dose of vaccine/placebo or scheduled within 14 days after injection Previously vaccinated with a live virus vaccine within 30 days before injection with the first dose of vaccine or scheduled within 14 days after injection Previously vaccinated with an inactivated vaccine within 5 days before injection with the first dose of vaccine or scheduled within 14 days after injection Known history of immunodeficiency History of malignancy (with some exceptions) Contraindication to intramuscular (IM) injection such as anticoagulant therapy or thrombocytopenia Female subject who is pregnant or breast feeding, or expecting to conceive or donate eggs through Week 30 of the study Male subject who is planning to impregnate or provide sperm donation through Week 30 of the study Previously received an investigational HIV vaccine Has active drug or alcohol abuse or dependence that would interfere with adherence to study requirements, or endanger the subject's health while on the study Has a condition that might endanger the subject's health or interfere with the evaluation of the study objectives