Safety, Tolerability, and Immunogenicity Study of Homologous Ad26 Mosaic Vector Vaccine Regimens or Heterologous Ad26 Mosaic and MVA Mosaic Vector Vaccine Regimens With Glycoprotein 140 (gp140) for Human Immunodeficiency Virus (HIV) Prevention

The purpose of this study is to assess the safety and tolerability of various regimens containing adenovirus serotype 26-Mosaic -Human Immunodeficiency Virus (Ad26.Mos.HIV), Modified Vaccinia Ankara (MVA)-Mosaic, and/or HIV type 1 Clade C glycoprotein 140 drug product (gp140 DP) components and to compare envelope binding antibody responses between the different vaccine regimens.

This is a multicenter (more than 1 hospital or medical school team work on a study), 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. All eligible participants will be randomly assigned to receive 1 of the 8 vaccine regimens. Participants will receive study vaccines (Ad26.Mos.HIV, MVA-Mosaic, gp140 DP, and placebo) 4 times as per assigned regimen. The study comprises a Screening Period (up to 4 weeks), a Vaccination Period (participants will be vaccinated at Baseline (Week 0), Week 12, Week 24 and Week 48), and a Follow-up Period (up to 48 weeks). A long-term follow-up period (approximately 2 years after Week 96) will continue for participants randomized to the regimen subsequently selected for future studies, based on analysis of Week 28 data. If Week 28 data are inconclusive, Week 52 data will be considered for regimen selection. If no clear decision can be made, the extended follow-up period could include participants from more than 1 group for assessing durability of immune responses. Participants' safety will be monitored throughout the study.

Eligibility Criteria:
Inclusion Criteria:

* Participant must be healthy on the basis of physical examination, medical history, electrocardiogram (ECG) and laboratory criteria, and vital signs measurement performed at Screening
* Participants are negative for human immunodeficiency virus (HIV) infection at Screening
* All female participants of childbearing potential must have a negative serum (beta human chorionic gonadotropin) at Screening, and a negative urine pregnancy test pre-dose on Week 0, 12, 24, and 48
* A woman must agree not to donate eggs (ova, oocytes) for the purposes of assisted reproduction until 3 months after receiving the last dose of study vaccine. A man must agree not to donate sperm until 3 months after receiving the last dose of study vaccine
* Participants are assessed by the clinic staff as being at low risk for HIV infection

Exclusion Criteria:

* Participant has chronic active hepatitis B or active hepatitis C, active syphilis infection, chlamydia, gonorrhea, or trichomonas. Active syphilis documented by exam or serology unless positive serology is due to past treated infection
* In the 12 months prior to enrollment, 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 any clinically significant acute or chronic medical condition that in the opinion of the investigator would preclude participation (for example, history of seizure disorders, bleeding/clotting disorder, autoimmune disease, active malignancy, poorly controlled asthma, active tuberculosis or other systemic infections)
* Participant has had major surgery within the 4 weeks prior to study entry or planned major surgery through the course of the study
* Participant has had a thyroidectomy, or thyroid disease requiring medication during the last 12 months
* Participant has a history of myocarditis, pericarditis, cardiomyopathy, congestive heart failure with permanent sequelae, clinically significant arrhythmia (including any arrhythmia requiring medication, treatment, or clinical follow up)
* Participant has an ECG (per examination and interpretation of a cardiologist) with clinically significant findings, or features that would interfere with the assessment of myo/pericarditis, including any of the following: a) conduction disturbance (complete left or complete right bundle branch block or nonspecific intraventricular conduction disturbance with QRS \>=120 millisecond \[ms\], PR interval \>=220 ms, any 2nd or 3rd degree AV block, or QTc prolongation \[\>450 ms\]); b) significant repolarization (ST segment or T wave) abnormality; c) significant atrial or ventricular arrhythmia, frequent atrial or ventricular ectopy (for example frequent premature atrial contractions, 2 premature ventricular contractions in a row); d) ST elevation consistent with ischemia, or evidence of past or evolving myocardial infarction
* Participant has a history of anaphylaxis or other serious adverse reactions to vaccines or vaccine products, or neomycin or streptomycin or egg products