There are two different ways a vaccine can protect the body from infection. First, a vaccine may help the immune system make antibodies, which are proteins that recognize invading viruses or bacteria. Second, a vaccine may help the body make immune cells that destroy infected cells. The second type of vaccine is more powerful against HIV. In this study, doctors will see whether vCP205, vCP1433, vCP1452, and gp160 are good vaccines by seeing whether they help the body make immune cells.