This study will test the safety of an experimental vaccine against HIV and examine whether it induces an immune response to HIV. A vaccine is a substance given to try to create resistance or immunity to a disease or infection. The vaccine in this study is made from DNA (genetic material) of four HIV proteins called 'gag', 'pol', 'Nef', and 'Env'. Injected into a human, the viral DNA instructs the body to make small amounts of some HIV proteins. This study will see if the body then creates an immune response to these proteins. Study participants cannot catch HIV or AIDS from the DNA vaccine or any proteins made from it.