To evaluate the safety and immunogenicity of a combination of microparticulate monovalent HIV-1 MN synthetic branched peptide candidate vaccine for oral administration and monovalent HIV-1 MN synthetic branched peptide vaccine in alum for intramuscular administration in intermediate or higher risk HIV-negative volunteers.
Inclusion Criteria Volunteers must have: * Normal history and physical exam. * HIV negativity. * CD4 count \>= 400 cells/mm3. * Intermediate or high risk sexual behavior or a history of injection drug use within 12 months prior to study entry. * Normal urine dipstick with esterase and nitrite. Exclusion Criteria Co-existing Condition: Volunteers with the following symptoms or conditions are excluded: * Active tuberculosis. * Occupational or other responsibilities that would prevent completion of study. Volunteers with the following prior conditions are excluded: * History of immunodeficiency, chronic illness, autoimmune disease, or use of immunosuppressive medications. * Psychiatric, medical, or substance abuse problems within the past 6 months that would affect ability to participate in study. * History of anaphylaxis or other serious adverse reactions to vaccines. * History of inflammatory gastrointestinal disease, celiac disease, or intestinal malignancy. * Acute gastroenteritis or gastrointestinal surgery within the past 12 months. Prior Medication: Excluded: * Live or attenuated vaccine within the past 60 days. * Illicit or experimental agents within the past 30 days. Intermediate or high risk sexual behavior. Injection drug use within the past 12 months.