Evaluating the Safety and Immune Response to an HIV Vaccine Boost Following the Administration of Two HIV Vaccines, in HIV-Uninfected, Healthy Adults (Study Extension to HVTN 073/SAAVI 102)

The HVTN 073/SAAVI 102 study is evaluating the safety of two experimental HIV vaccines-SAAVI DNA-C2 and SAAVI MVA-C-given sequentially as a prime-boost regimen in healthy, HIV-uninfected adults. This is an extension of that study and will enroll people who participated in the HVTN 073/SAAVI 102 study. Previous studies have shown that a protein vaccine boost to an HIV vaccine may improve antibody responses. This study will evaluate the safety and immune response to an HIV envelope protein vaccine-the Sub C gp140 vaccine with MF59 adjuvant-in healthy, HIV-uninfected adults who have previously participated in the HVTN 073/SAAVI 102 study. Study researchers will explore whether the addition of a protein boost vaccine to the SAAVI DNA-C2 and SAAVI MVA-C vaccine regimen improves antibody response. This study will enroll people who participated in the HVTN 073/SAAVI 102 study,regardless of whether they received vaccine or placebo. Participants will be randomly assigned to receive either the Sub C gp140 vaccine with MF59 adjuvant or a placebo injection during study visits at baseline and Month 3. At the baseline and Month 3 visits, participants will undergo a physical examination, HIV testing and counseling, pregnancy testing for female participants, interviews and questionnaires, risk reduction counseling, and blood collection (at the baseline visit only). They will then receive their assigned vaccine or placebo as one injection in their upper arm. Participants will remain in the clinic for 30 minutes after receiving the vaccination for observation and monitoring. For 3 days after the vaccination, participants will record any side effects in a symptom log and make contact daily with the study site staff. Additional study visits will occur at Weeks 1 and 2, 1 and 2 weeks after the Month 3 visit, and Months 6 and 9. At these visits, select baseline study procedures will occur. At Month 15, study staff will contact participants for follow-up health monitoring. Participants will then complete any annual health contacts for the original HVTN 073/SAAVI 102 study.