A Safety, Tolerability and Immunogenicity Study of 2 Different Regimens of Tetravalent Ad26.Mos4.HIV Prime Followed by Boost With Tetravalent Ad26.Mos4.HIV Along With Either Clade C gp140 Plus Adjuvant OR With a Combination of Mosaic and Clade C gp140 Plus Adjuvant in Healthy HIV Uninfected Adults

Prior treatment

• In the 12 months prior to randomization, participant has a history of newly acquired herpes simplex virus type 2 (HSV-2), syphilis, gonorrhea, non-gonococcal urethritis, chlamydia, pelvic inflammatory disease, trichomonas, mucopurulent cervicitis, epididymitis, proctitis, lymphogranulomavenereum, chancroid, or hepatitis B
• Participant has had major surgery (eg, requiring general anesthesia) within the 4 weeks before screening, or will not have fully recovered from surgery, or has surgery planned through the course of the study
• Current or past drug/alcohol use that investigator assesses poses any more than a remotely increased risk of the ability of the participant to comply with the protocol requirements
• Has been in receipt of any licensed vaccine within 14 days prior to the first dose of study vaccine or placebo, plans to receive within 14 days after the first study vaccination, or plans to receive within 14 days before or after the second, third or fourth vaccination
• Is a recipient of a prophylactic or therapeutic HIV vaccine candidate at any time, or a recipient of other experimental vaccine(s) within the last 12 months prior to the Day 1 visit (Vaccination 1). For participants who received an experimental vaccine (except HIV vaccine) more than 12 months prior to the Day 1 visit (Vaccination 1), documentation of the identity of the experimental vaccine must be provided to the sponsor, who will determine eligibility on a case-by-case basis

Other illness

• Has chronic hepatitis B (measured by hepatitis B surface antigen test) or active hepatitis C (measured by hepatitis C virus \[HCV\] Ab test; if positive, HCV ribonucleic acid \[RNA\] polymerase chain reaction (PCR) test will be used to confirm active versus past HCV infection), active syphilis infection, chlamydia, gonorrhea, or trichomonas
• Participant has had a thyroidectomy or active thyroid disease requiring medication during the last 12 months (not excluded: a stable thyroid supplementation)

• Participant must be healthy on the basis of medical history, physical examination, and vital signs measurement performed at screening
• Participants are negative for human immunodeficiency virus (HIV) infection at screening
• Participants are amenable to HIV-risk reduction counseling and committed to maintaining behavior consistent with low risk of HIV exposure through the last required protocol clinic visit
• All female participants of childbearing potential must have a negative serum (beta-human chorionic gonadotropin \[beta-hCG\]) at the screening visit, and a negative urine pregnancy test pre-dose on Day 1
• Participants are willing/able to adhere to the prohibitions and restrictions specified in the protocol and study procedures
• Participant must be enrolled in the LTE phase to receive the late boost vaccination