A Phase I Clinical Trial to Evaluate:Part A. The Safety and Immunogenicity of Two Dose Levels of SF-2 gp120 (CHO) With or Without MTP-PE Adjuvant in the MF59 Emulsion Part B. The Safety and Immunogenicity of Five Monthly Doses of 50 mcg gp120 Protein in MF59 Emulsion (Without MTP-PE) Versus the Emulsion Control

Inclusion Criteria

Patients must have:

• Normal history and physical exam.
• No identifiable high-risk behavior for HIV infection.
• Negative ELISA for HIV.
• Normal cell-mediated immune responses using Merieux skin test.

Exclusion Criteria

Co-existing Condition:

Patients with the following symptoms or conditions are excluded:

• Significant evidence of depression.
• Positive syphilis serology (e.g., RPR) that is documented not to be a false positive or from a remote (> 6 months) treated infection.
• Circulating Hepatitis B antigenemia.
• More than two sexual partners, or sexual contact with a high-risk partner, within the past 6 months.

Patients with the following prior conditions are excluded:

• History of immunodeficiency, chronic illness, autoimmune disease, or use of immunosuppressive medications.
• Significant evidence of depression or under treatment for psychiatric problems within the past year.
• History of anaphylaxis or other adverse vaccine reactions.
• Syphilis, gonorrhea, or any other sexually transmitted diseases (including chlamydia or pelvic inflammatory disease) within the past 6 months.

Prior Medication:

Excluded:

• Immunoglobulin or vaccines within the past 2 months.
• Experimental agents within the past 30 days.

Prior Treatment:

Excluded:

• Blood transfusions or cryoprecipitates within the past 3 months.

Risk Behavior: Excluded:

• History of IV drug use within the past year.
• More than two sexual partners, or sexual contact with a high-risk partner, within the past 6 months.

History of severe allergic reactions to study medication Currently pregnant or breastfeeding Recent participation in another clinical trial within the last 30 days Presence of uncontrolled medical conditions that could affect safety