Inclusion Criteria

Subjects must have:

• Normal history and physical exam.
• HIV negativity by ELISA within 6 weeks of immunization.
• CD4 count >= 400 cells/mm3.
• Normal urine dipstick with esterase and nitrite.

Exclusion Criteria

Co-existing Condition:

Subjects with the following symptoms or conditions are excluded:

• Hepatitis B surface antigen.
• Medical or psychiatric condition or occupational responsibilities that preclude compliance.
• Active syphilis. NOTE: Subjects with serology documented to be 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, autoimmune disease, or use of immunosuppressive medications.
• History of anaphylaxis or other serious adverse reactions to vaccines.
• History of allergy to thimerosal.
• AS PER AMENDMENT 07/02/97: History of eczema or allergic-type reactions to rsgp120/HIV-1MN vaccine (for volunteers undergoing DTH testing).

Prior Medication:

Excluded:

• Live attenuated vaccines within 60 days prior to study entry. (NOTE: Medically indicated subunit or killed vaccines, such as influenza or pneumococcal, are allowed but should be given at least 2 weeks prior to HIV immunizations.)
• Experimental agents within 30 days prior to study entry.
• Prior HIV vaccines.
• AS PER AMENDMENT 07/02/97: Use of systemic steroids in the past month (for volunteers undergoing DTH testing).

Prior Treatment:

Excluded:

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

Identifiable high-risk behavior for HIV infection as determined by screening questionnaire, including history of injection drug use within the past year and higher or intermediate risk sexual behavior.