Inclusion Criteria

Volunteers must have:

• Good health as determined by medical history, physical examination, and clinical judgment.
• Negative serology for HIV infection as determined by licensed HIV ELISA test performed within 6 weeks prior to first immunization.
• In vitro Epstein-Barr virus-immortalized cell line from peripheral blood can be established (required for selected Part B volunteers only).

Exclusion Criteria

Co-existing Condition:

Volunteers with the following symptoms or conditions are excluded:

• Significant acute systemic infection.
• Occupational or other responsibilities that would prevent completion of participation in the study.
• Any condition that might interfere with the evaluation of the study objectives.

Volunteers with the following prior conditions are excluded:

• History of immunodeficiency, autoimmune disease, or any serious chronic illness.
• Evidence of psychiatric or medical history or substance abuse that would adversely affect the volunteer's ability to participate in the trial.

• History of anaphylaxis or other serious adverse reactions to vaccines or vaccine components.

  1. Immunosuppressive medications.

• Live, attenuated vaccine within 60 days of study entry.

NOTE:

• Medically indicated subunit or killed vaccines (e.g., influenza or pneumococcal) are not exclusionary but should be given at least 4 weeks before or after HIV immunizations to avoid potential confusion of adverse reactions.
• Experimental agents within 30 days of study entry.
• HIV vaccine or MF59 adjuvant. Blood products or immunoglobulins in the past 3 months.

Engaging in high-risk behavior within 6 months of study entry, i.e.:

• injection drug use, sexual intercourse without a condom with 4 or more partners or with known iv drug user or HIV+ partner, or newly acquired sexually-transmitted disease.