 The purpose of this study is to determine the safety of and immune response to an experimental HIV vaccine, HIV-1 gag DNA, with and without an IL-15 DNA adjuvant at escalating doses of 100, 500, and 1500 mcg. This study will also test the safety of and immune response to the HIV-1 gag DNA vaccine plus IL-15 DNA adjuvant given with or without 2 other adjuvant-containing booster vaccines. 