MSP2-C1

This study is a multi-center, double-blind, placebo-controlled, Phase I study to evaluate the safety, reactogenicity, tolerability, and immunogenicity of Modified Vaccinia Ankara-Bavarian Nordic-Yellow Fever (MVA-BN-YF) in Flavivirus-naive healthy male and non-pregnant female adult subjects. There are six dose groups in this study. Subjects who have never received a licensed or investigational smallpox vaccine will be randomized to Groups 1-5 and vaccine administration and follow-up will be conducted in a double-blinded fashion. Subjects who have previously received two, 1 x 10^8 TCID50 doses of Modified Vaccinia Ankara-Bavarian Nordic (MVA-BN) between 19 and 45 days apart by s ubcutaneous (SC) or intramuscular (IM) routes will be enrolled in Group 6 and will be dosed open-label. Since this is a first in human, phase I study, a sentinel cohort will be utilized. The first two subjects (1st sentinel group) one at each clinical site will be randomized to Group 2 or 3 and vaccinated with MVA-BN-YF with or without Montanide ISA 720 adjuvant (ISA 720). Subjects and study personnel will be blinded as to whether ISA 720 was administered. The primary objectives are the: 1) assessment of the safety, tolerability, and reactogenicity of MVA-BN-YF vaccine administered with or without ISA 720; 2) comparison of the safety, tolerability, and reactogenicity of MVA-BN-YF vaccine administered with or without ISA 720 with Yellow Fever Vaccine (YF-VAX) and MVA-BN.