Safety of and Immune Response to Prime/Boost Vaccine Regimens in Healthy, HIV-1 Uninfected, Ad5 Seronegative Adults

Investigators will examine the safety of and immune responses to two vaccines expressing synthetic HIV proteins: NYVAC-B (a poxvirus), and rAd5 (an adenovirus). The study will compare responses in participants receiving NYVAC-B first, and rAd5 later, to those who receive rAd5 first, and NYVAC-B later. A different dose of rAd5 will be tested in each group.