The main study, HVTN 205 will evaluate the safety of and immune response to a two vaccine regimen in healthy, HIV-uninfected adults who never received an HIV preventive vaccine before. HVTN 205 will include two parts, Part A, in which the two vaccine regimen is compared to a placebo, and Part B, in which the two vaccine regimen will be compared to both a placebo and a single vaccine regimen with the rMVA vaccine.