Inclusion Criteria

Subjects must have:

• Normal history and physical exam.
• HIV negativity by ELISA within 8 weeks of study entry.
• Absolute CD4 count >= 400 cells/mm3.
• Normal urine dipstick with esterase and nitrite.
• Lower or intermediate risk sexual behavior.

NOTE:

• No more than 10 percent of subjects may be over 50 years of age.

Exclusion Criteria

Co-existing Condition:

Subjects with the following symptoms or conditions are excluded:

• Positive hepatitis B surface antigen.
• Medical or psychiatric condition (such as psychosis or suicidal tendencies) or occupational responsibilities that preclude study compliance.
• Active syphilis. NOTE: Subjects whose serology is documented to be a false positive or due to a remote (> 6 months) treated infection are eligible.
• Active tuberculosis. NOTE: Subjects with a positive PPD and normal chest x-ray showing no evidence of TB and not requiring isoniazid therapy are eligible.

Subjects with the following prior conditions are excluded:

• History of immunodeficiency, chronic illness, or autoimmune disease.
• History of anaphylaxis or other serious reactions to vaccines.
• History of inflammatory gastrointestinal disease, celiac disease, or intestinal malignancy.
• History of acute gastroenteritis within the past month or gastrointestinal surgery within the past year.
• History of cancer unless there has been surgical excision with reasonable assurance of cure.
• History of serious allergic reaction.

Prior Medication:

Excluded:

• History of immunosuppressive medications.
• Live attenuated vaccines within 60 days prior to study entry (NOTE: Medically indicated subunit or killed vaccines, e.g., influenza or pneumococcal, are not exclusionary, but should not be given within 2 weeks of HIV immunization).
• Experimental agents within 30 days prior to study entry.
• Prior HIV vaccines.

Prior Treatment:

Excluded:

• Blood products or immunoglobulin within the past 6 months.

Identifiable higher risk behavior for HIV infection, including the following:

• History of injection drug use within the past 12 months.
• Higher risk sexual behavior as defined by the AVEG.