This study will consist of two groups, with Group 1 enrolling first. Group 1 participants will be randomly assigned to receive either 10^3 PFU of rDEN3delta30/31-7164 or placebo subcutaneously in their deltoid. Participants will be monitored at the clinic for 30 minutes after receiving the immunization to monitor for adverse effects. After that, participants will be asked to return to the clinic approximately every other day for the next 16 days, and then on Day 21, 28, 42, and 180. At each visit participants will have physical and clinical exams, vital signs, measures, blood drawn, and will be asked about any adverse events they may have experience. Female participants will be given a pregnancy test. In addition, participants will be asked to measure their temperature 3 times a day and record it in a temperature diary for the first 16 days after immunization.