Vaccines are given to people to help their bodies fight infection. The vaccine being tested in this study is a DNA vaccine. The pGA2/JS2 plasmid DNA vaccine instructs the body to make some HIV proteins. These HIV proteins may trigger an immune response. Because only a few of the many proteins HIV needs are made through DNA vaccination, there is no risk of getting HIV from the vaccination. This and other similar DNA vaccines have been tested for safety in mice, rabbits, and monkeys. The vaccine has been well tolerated at doses to be used in this study.