This Phase 1/1b study will examine dose, safety, tolerability and immunogenicity of an investigational MVA-vectored Ebola vaccine in healthy adults. The vaccine encodes wild type (WT) glycoprotein (GP) from Zaire strain of Ebola and will be administered intramuscularly (IM) with needle and syringe. The safety and tolerability of the MVA-EbolaZ will be evaluated at escalating doses of 1x10(7) and 1x10(8) plaque forming units (PFU). Part 1 includes enrollment of vaccine-naive subjects to conduct a dose escalation of the MVA-EbolaZ vaccine and to evaluate the vaccine as a boost for the cAd3-EBO vaccine. In Part 2 of the study, up to 140 subjects who received the cAd3-EBO or cAd3-EBOZ vaccine in VRC 207 study will be boosted with MVA-EbolaZ. The hypotheses are that the study vaccines will be safe and elicit immune responses to Ebola GP, and that the prime-boost regimens will be safe and result in a more polyfunctional response to Ebola GP that is of greater magnitude and duration than response to either of the vaccines alone.