The AMP study is a new idea for HIV prevention that is related to what has been done in HIV vaccine research. In traditional HIV vaccine studies, people get a vaccine and researchers wait to see if their bodies will make antibodies against HIV in response. In this study, we will skip that step, and give people the antibodies directly. We will do this with an intravenous infusion, commonly known as an “IV” or “getting a drip”. This is the first study testing whether antibodies can prevent HIV infections in people.