This is a phase 1 single-center, randomized (the study drug is assigned by chance), parallel group (each group of participants will be treated at the same time), placebo-controlled (study in which the experimental treatment or procedure is compared to a pretend treatment with no drug in it to test if the drug has a real effect), and double-blind (neither physician nor participant knows the treatment that the participant receives) study. Participants will be randomized in to 3 groups and will receive study vaccines or placebo. Group 1 will have 4 vaccination time points during 48 weeks, Groups 2 and 3 will have 3 vaccination time points during 24 weeks. The study comprises a Screening Period (up to 4 weeks), a Vaccination Period (maximum 48 weeks), and a Follow-up Period (up to 72 weeks). Participants' safety will be monitored throughout the study. An optional Long-term Extension (LTE) phase (approximately 1 year after Week 72) will be performed for participants randomized to receive study vaccine, who have received all planned vaccinations and are negative for HIV infection at Week 72. The duration of the participation will be approximately 124 weeks for participants participating to the optional LTE phase.
