This study will test the safety of an experimental vaccine developed to protect against Ebola virus infection and to determine if the vaccine induces an immune response to the virus. The Ebola virus causes a disease called Ebola hemorrhagic fever. Symptoms begin with fever and muscle aches and progress to breathing problems, severe bleeding, kidney problems, and shock. The infection may be mild, but it can also lead to death. The vaccine used in this study is made from small parts of Ebola genetic material. It cannot cause Ebola hemorrhagic fever to develop in those who receive it.