The purpose of this study is to determine the safety of a new HIV vaccine. The vaccine in this study is mixed with a chemical called alum to improve the body's response to the vaccine. Healthy adults who are not infected with HIV may participate in the study.

EnvPro is a recombinant, purified envelope protein vaccine with an aluminum hydroxide (alum) adjuvant. Aluminum hydroxide is licensed as an adjuvant in other vaccines, such as the hepatitis B vaccine. This study will examine the safety and tolerability of EnvPro with alum adjuvant in healthy, HIV uninfected adults.

All participants in this study will receive vaccine injections in the upper arm muscle. Participants will receive a second vaccine injection eight weeks after the first injection. Blood tests will be performed at study visits before the vaccine is given, during the eight weeks between injections, and at selected times for up to three years after the vaccine is given.

Inclusion Criteria:

• HIV uninfected
• Normal medical history and physical exam
• Normal complete blood count
• Normal liver function
• Normal renal function
• Normal serum creatine phosphokinase (CPK)
• Availability for at least 1 year follow-up

Exclusion Criteria:

• History of immunosuppressive illness, chronic illness, or use of any immunosuppressive medications
• Medical or psychiatric condition or occupational responsibilities which preclude compliance with the study
• Live attenuated vaccines within 60 days of study entry
• Use of experimental agents within 30 days of study entry