Inclusion Criteria

Volunteers must have:

• Negative ELISA for HIV within 8 weeks of immunization.
• Normal history and physical examination.
• Normal chest x-ray within 4 weeks prior to initial immunization.
• Low-risk sexual behavior as defined by AVEG.

Exclusion Criteria

Co-existing Condition:

Volunteers with the following conditions are excluded:

• Medical or psychiatric condition that precludes compliance with the protocol, including recent suicidal ideation or present psychosis.
• Occupational responsibilities which preclude compliance with the protocol.
• Active syphilis (if the serology is documented to be a false positive or due to a remote [more than 6 months] treated infection, the volunteer is eligible).
• Active tuberculosis (volunteers with a positive purified protein derivative and a normal chest x-ray showing no evidence of TB and not requiring isoniazid therapy are eligible).
• Positivity for hepatitis B surface antigen.

Volunteers with the following prior conditions are excluded:

• History of immunodeficiency, chronic illness, malignancy, or autoimmune disease. NOTE: Individuals with a history of cancer are excluded unless there has been surgical excision followed by a sufficient observation period to give a reasonable assurance of cure.
• History of suicide attempts or past psychosis.
• History of anaphylaxis or other serious adverse reactions to vaccines.
• History of serious allergic reaction to any substance, requiring hospitalization or emergent medical care (e.g., Stevens-Johnson syndrome, bronchospasm, or hypotension).
• History of lung disease.

Prior Medication:

Excluded:

• Live attenuated vaccines within 60 days of study. NOTE: Medically indicated subunit or killed vaccines (e.g., influenza, pneumococcal) are not exclusionary, but should be given at least 2 weeks away from HIV immunizations.
• Experimental agents within 30 days prior to study.
• HIV-1 vaccines or placebo, received in a previous HIV vaccine trial.
• Immunosuppressive medications.

Prior Treatment:

Excluded:

• Receipt of blood products or immunoglobulin in the past 6 months.

Risk Behavior: Excluded:

• Alcohol intake greater than or equal to the equivalent of 1 oz of 100 proof per day (4 oz. glass of wine or 12 oz. of beer per day).
• Identifiable higher-risk behavior for HIV infection as determined by screening questions designed to identify risk factors for HIV infection; specific exclusions include a history of injection drug use within the last 12 months prior to enrollment and higher- or immediate-risk sexual behavior as defined by the AVEG (i.e., meeting the criteria for AVEG Risk Groups C and D).