Previous clinical trials have shown that people who receive a second vaccine for certain conditions after having received a prior vaccine may have a better antibody response to the second vaccine than people who receive the vaccine for the first time. This is known as priming and it may occur in people receiving a second vaccine even if the first vaccine was received several years previously. This study will enroll healthy, HIV-uninfected adults who have participated in a previous HIV vaccine clinical trial and received HIV-1 subtype B envelope subunit vaccines with MF59 adjuvant, and healthy, HIV-uninfected adults who have not participated in a previous HIV vaccine clinical trial and therefore have not previously received any HIV vaccines. Participants in this study will receive a total of two injections, each 6 months apart, of the HIV-1 Sub Cgp140 vaccine with MF59 adjuvant. Researchers will evaluate the safety and immune response to the study vaccine and determine if people who participated in a previous HIV vaccine clinical trial demonstrate an improved antibody response to the study vaccine versus people who have never received an HIV vaccine.~This study will enroll two groups of participants. Group 1 will include healthy, HIV-uninfected adults who have participated in a previous HIV vaccine clinical trial. Group 2 will include healthy, HIV-uninfected adults who have not participated in an HIV vaccine clinical trial. All participants will receive the study vaccine injected into their upper arm at baseline and Month 6.~At the baseline study visit, all participants will undergo a physical examination, a medical and medication history review, and blood collection. Female participants will also take a pregnancy test. Participants will complete questionnaires and receive counseling on HIV risk reduction and pregnancy prevention. Saliva samples will be obtained from all participants and rectal fluids, semen samples, and cervical secretions will be obtained from some participants. After receiving the vaccine, participants will remain in the clinic for at least 30 minutes for observation and monitoring of side effects. For 3 days after the vaccination, participants will record any side effects in a symptom log.~Participants in Group 1 will attend study visits 1 and 2 weeks after the first vaccination study visit, at Month 6 for the second vaccination, 1 and 2 weeks after the Month 6 study visit, and at Months 9 and 12. Participants in Group 2 will attend study visits 1 and 3 days and 1 and 2 weeks after the first vaccination study visit, at Month 6 for the second vaccination, 1 and 3 days and 1 and 2 weeks after the Month 6 study visit, and at Months 9 and 12. Follow-up study visits will include select study procedures. Blood collected during study visits may be saved for future testing. Study researchers will contact participants at Month 18 for follow-up health monitoring.~In July 2013, an extension to the study was announced. Current study participants will be screened to see if they are eligible to participate in the study extension. Participants who are eligible will receive one additional injection of the study vaccine, at a visit approximately 14 to 20 months after their second (Month 6) vaccination. Additional study visits will occur 2 weeks, and 3 and 6 months after receiving the third vaccination. Select visits will include a physical examination, blood collection, saliva collection, pregnancy test for female participants, HIV testing and risk reduction counseling, and interviews and questionnaires. Study researchers will contact participants 1 year after the third vaccination for follow-up health monitoring.
The purpose of this study is to evaluate the safety and immune response to an HIV vaccine in healthy, HIV-uninfected adults who have participated in a previous HIV vaccine clinical trial and in healthy, HIV-uninfected adults who have not participated in a previous HIV vaccine clinical trial.