This is a first time in humans (FTiH) study designed to assess the experimental TDENV-PIV vaccine in a predominantly dengue-primed adult population. The study is designed to afford a first time in humans (FTiH) safety and immunogenicity assessment of three TDENV-PIV vaccine candidates, each formulated with a different adjuvant: either aluminum hydroxide, AS01E or AS03B (adjuvants used in GSK Biologicals' hepatitis B candidate vaccine, malaria candidate vaccine and pandemic flu vaccine, respectively). Each vaccine candidate will contain 1 µg of purified virus antigen per each of the four DENV types. Additionally, the study will evaluate an alum adjuvanted TDENV-PIV vaccine candidate containing 4 µg of purified virus antigen per each of the four DENV types. The control group will receive a saline placebo. All experimental vaccinations will be administered according to a 2-dose schedule, 28 days apart. There is a parallel FTiH study that is conducted in the United States in a dengue-naive population using the same investigational vaccines.