VRC 208: Dose, Safety and Immunogenicity of a Recombinant Modified Vaccinia Virus Ankara Ebola Vaccine, VRC-EBOMVA079-00-VP (MVA-EbolaZ), Administered Alone or as a Boost to cAd3-Ebola Vaccines in Healthy Adults

* INCLUSION CRITERIA: Inclusion Criteria for Groups 1, 2, and 3. A volunteer must meet all of the following criteria to be eligible: 1. 18 to 50 years old. 2. Available for clinical follow-up through the last study visit. 3. Able to provide proof of identity to the satisfaction of the study clinician completing the enrollment process. 4. Able and willing to complete the informed consent process. 5. Willing to donate blood for sample storage to be used for future research. 6. In good general health without clinically significant medical history. 7. Physical examination and laboratory results without clinically significant findings and a body mass index (BMI) less than or equal to 40 within the 56 days prior to enrollment. Laboratory Criteria within 56 days prior to enrollment: 8. Hemoglobin within institutional normal range or accompanied by the Principal Investigator (PI) or designee approval. 9. White blood cells (WBC) = 3,300-12,000 cells/mm(3). 10. WBC differential either within institutional normal range or accompanied by the PI or designee approval. 11. Total lymphocyte count greater than or equal to 800 cells/mm(3). 12. Platelets = 125,000-400,000/mm(3). 13. Alanine aminotransferase (ALT) less than or equal to 1.25 times upper limit of normal. 14. Serum creatinine less than or equal to 1.1 times upper limit of normal. 15. Partial thromboplastin time (PTT) less than or equal to 1.1 times upper limit of normal or accompanied by the Principal Investigator (PI) or designee approval. 16. Prothrombin time (PT) less than or equal to1.1 times upper limit of normal or accompanied by the Principal Investigator (PI) or designee approval. 17. HIV-uninfected as evidenced by a negative FDA-approved HIV diagnostic blood test. -Female-Specific Criteria: 18. Negative beta-HCG (human chorionic gonadotropin) pregnancy test (urine or serum) on day of enrollment if woman is presumed to be of reproductive potential. 19. Agrees to use an effective means of birth control from at least 21 days prior to enrollment through 24 weeks after last study vaccination if presumed to be of reproductive potential. EXCLUSION CRITERIA: Exclusion Criteria for Groups 1, 2, and 3 A volunteer will be excluded if one or more of the following conditions apply: Volunteer has received any of the following substances: 1. Investigational Marburg vaccine in a prior clinical trial. 2. Investigational Ebola vaccine in a prior clinical trial. 3. Investigational cAd3 or MVA vaccines in a prior clinical trial. 4. Evidence of increased cardiovascular disease risk defined as \>10% five year risk by the non-laboratory method. 5. Electrocardiogram (ECG) with clinically significant abnormalities (examples may include: pathologic Q waves, significant ST-T wave changes, left ventricular hypertrophy, any non-sinus rhythm excluding isolated premature atrial contractions, right or left bundle branch block, advanced A-V heart block). ECG abnormalities determined by a cardiologist to be clinically insignificant as related to study participation do not preclude study enrollment. 6. Type 1 hypersensitivity reaction to aminoglycoside antibiotics. 7. More than 10 days of systemic immunosuppressive medications except for short-term treatments of minor ailments in otherwise healthy volunteers, or cytotoxic medications within the 4 weeks prior to enrollment, or any within the 14 days prior to enrollment. 8. Blood products within 112 days (16 weeks) prior to enrollment. 9. Investigational research agents within 28 days (4 weeks) prior to enrollment. 10. Live attenuated vaccines within 28 days (4 weeks) prior to enrollment. 11. Medically indicated subunit or killed vaccines, e.g. influenza, pneumococcal within 2 weeks of initial study vaccine administration unless approved by the study Principal Investigator (PI) or designee 12. Current anti-tuberculosis prophylaxis or therapy. -Female-specific criteria: 13. Woman who is breast-feeding or planning to become pregnant during the 24 weeks of study participation. -Volunteer has a history of any of the following clinically significant conditions: 14. Serious adverse reactions to vaccines such as anaphylaxis, urticaria (hives), respiratory difficulty, angioedema, or abdominal pain. 15. Clinically significant autoimmune disease or immunodeficiency. 16. Asthma that is not well controlled. 17. Diabetes mellitus (type I or II), with the exception of gestational diabetes. 18. Thyroid disease that is not well controlled. 19. A history of hereditary angioedema (HAE), acquired angioedema (AAE), or idiopathic forms of angioedema. 20. Idiopathic urticaria within the last 1 year. 21. Hypertension that is not well controlled. 22. Bleeding disorder diagnosed by a doctor (e.g. factor deficiency, coagulopathy, or platelet disorder requiring special precautions) or significant bruising or bleeding difficulties with IM injections or blood draws. 23. Malignancy that is active or history of a malignancy that is likely to recur during the period of the study. 24. Seizure in the past 3 years or treatment for seizure disorder in the past 3 years. 25. Asplenia or functional asplenia. 26. Psychiatric condition that precludes compliance with the protocol; past or present psychoses; or within five years prior to enrollment, history of a suicide plan or attempt. 27. Any medical, psychiatric, social condition, occupational reason or other responsibility that, in the judgment of the investigator, is a contraindication to protocol participation or impairs a volunteer s ability to give informed consent.