Inclusion Criteria

Subjects must have:

• Normal history and physical exam.
• Negative HIV screening by ELISA, Western blot, and p24 antigen (PBMC HIV culture or HIV-specific PCR can be substituted for Western blot and p24 antigen).
• No history of smallpox (vaccinia) vaccination.
• Normal urinalysis.
• Absolute CD4 count = or > 500 cells/mm3.

Exclusion Criteria

Co-existing Condition:

Subjects with the following conditions are excluded:

• Hepatitis B surface antigenemia.
• Medical or psychiatric condition that precludes compliance with the protocol.

Subjects with the following prior conditions are excluded:

• History of immunodeficiency or chronic illness.
• Eczema within the past year.

Prior Medication:

Excluded:

• Prior experimental HIV vaccine.
• Prior smallpox vaccine.
• Immunoglobulin administration within 2 months prior to enrollment.
• Any experimental agent within 2 months prior to enrollment.
• History of use of immunosuppressive medications.

Prior Treatment:

Excluded:

• Blood or blood product transfusion within the past 6 months.

  1. Current high risk for HIV transmission (persons previously at high risk for HIV transmission can be enrolled provided they have a negative HIV screening and no high-risk behavior has been practiced within the last 6 months).

• Household contact with anyone who is pregnant, has eczema, is less than 12 months of age, or has immunodeficiency disease or is using immunosuppressive medications.