Study of the Safety and Pharmacokinetics of a Human Monoclonal Antibody, VRC-HIVMAB060-00-AB (VRC01), Administered Intravenously or Subcutaneously to Healthy Adults

Background: \- VRC01 is a manmade antibody directed against the human immunodeficiency virus (HIV). Antibodies fight infection. Researchers eventually want to know if VRC01 helps prevent or treat HIV infection. In this study they want to know if the study drug is safe if taken in a vein or under the skin. Taking VRC01 in this study will not protect against HIV infection. Objectives: \- To see if VRC01 and placebo are safe and well tolerated. Eligibility: \- Healthy adults 18 to 50 years old. Design: * Participants will be screened with medical history, physical exam, and lab tests. * Participants will be randomly divided into 4 groups. VRC01 or the placebo will be given in weeks 1 and 4. Blood samples will be taken several times after each VRC01 or placebo dose. * Three groups will receive VRC01 by needle into a vein with an IV pump. It will take about 1 hour and it is done in the hospital. * One group will receive either VRC01 or the placebo by needle into the fatty tissue under the skin, usually the belly. It will take up to 20 minutes and it is done in the hospital. * Participants will stay in the hospital overnight after receiving the medication and have about 14 clinic visits over 4 months. Most clinic visits last about 2 hours. * Participants will keep a symptom diary after receiving the medicatino. * Participants can volunteer to have mouth, rectal, and genital samples taken throughout the study. * The study will last 8 months.