Primary: To determine whether additional boosting with soluble recombinant gp160 vaccine (VaxSyn) after priming with a vaccinia-HIV envelope recombinant (HIVAC-1e) provides a significant advantage in the degree and duration of immunogenicity. Secondary: To learn more about the safety of the combination use of the two HIV envelope vaccines in the study (VaxSyn and HIVAC-1e).

Recent Phase I trials conducted at the AIDS Vaccine Units have shown that antibodies have persisted in most recipients for 6 months after boosting, and responses seem significantly higher and more persistent than responses achieved by just two doses of soluble protein vaccine alone or two doses of HIVAC-1e alone. This study tests in a previously recruited cohort of volunteers whether additional boosting with soluble recombinant gp160 results in increased immunogenicity of longer duration.

Recent Phase I trials conducted at the AIDS Vaccine Units have shown that antibodies have persisted in most recipients for 6 months after boosting, and responses seem significantly higher and more persistent than responses achieved by just two doses of soluble protein vaccine alone or two doses of HIVAC-1e alone. This study tests in a previously recruited cohort of volunteers whether additional boosting with soluble recombinant gp160 results in increased immunogenicity of longer duration.

Twelve volunteers who have previously received two doses of HIVAC-1e (or DryVax) and two doses of gp160 receive an additional boost of gp160 at 12-20 months after the last boost and an additional dose of HIVAC-1e at least 9 months after the final gp160 boost.

• Biological: HIVAC-1e
• Biological: gp160 Vaccine (MicroGeneSys)

• McElrath MJ, Corey L, Greenberg PD. Evaluation of cytotoxic T cell responses to candidate HIV-1 vaccines in HIV-1-uninfected individuals. AIDS Res Hum Retroviruses. 1994;10 Suppl 2:S69-72.
• Kent SJ, Greenberg PD, Hoffman MC, Akridge RE, McElrath MJ. Antagonism of vaccine-induced HIV-1-specific CD4+ T cells by primary HIV-1 infection: potential mechanism of vaccine failure. J Immunol. 1997 Jan 15;158(2):807-15.
• Mosier DE, Gulizia RJ, MacIsaac PD, Corey L, Greenberg PD. Resistance to human immunodeficiency virus 1 infection of SCID mice reconstituted with peripheral blood leukocytes from donors vaccinated with vaccinia gp160 and recombinant gp160. Proc Natl Acad Sci U S A. 1993 Mar 15;90(6):2443-7.
• McElrath MJ, Rabin M, Hoffman M, Klucking S, Garcia JV, Greenberg PD. Evaluation of human immunodeficiency virus type 1 (HIV-1)-specific cytotoxic T-lymphocyte responses utilizing B-lymphoblastoid cell lines transduced with the CD4 gene and infected with HIV-1. J Virol. 1994 Aug;68(8):5074-83.
• McElrath MJ, Corey L, Greenberg PD, Matthews TJ, Montefiori DC, Rowen L, Hood L, Mullins JI. Human immunodeficiency virus type 1 infection despite prior immunization with a recombinant envelope vaccine regimen. Proc Natl Acad Sci U S A. 1996 Apr 30;93(9):3972-7.
• Cooney EL, McElrath MJ, Corey L, Hu SL, Collier AC, Arditti D, Hoffman M, Coombs RW, Smith GE, Greenberg PD. Enhanced immunity to human immunodeficiency virus (HIV) envelope elicited by a combined vaccine regimen consisting of priming with a vaccinia recombinant expressing HIV envelope and boosting with gp160 protein. Proc Natl Acad Sci U S A. 1993 Mar 1;90(5):1882-6.

Inclusion Criteria

Patients must have:

• Normal history and physical exam.
• Negative ELISA for HIV.
• Negative HIV p24 antigen test.
• Normal urinalysis.

Prior Medication: Required:

• Two prior doses of HIVAC-1e (or DryVax) and two prior doses of gp160 vaccine.

Exclusion Criteria

Co-existing Condition:

Patients with the following symptoms and conditions are excluded:

• Risk factors for HIV infection including active intravenous drug use and more than 2 sexual partners.
• History of immunodeficiency or chronic illness.
• Hypersensitivity to insects.
• Medical or psychiatric condition that makes it unlikely the patient will comply with the protocol.

Patients with the following prior conditions are excluded:

• History of immunodeficiency or chronic illness.

Prior Medication:

Excluded:

• Immunosuppressive medications.

Prior Treatment:

Excluded:

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

Risk Behavior: Excluded:

• Intravenous drug use.
• More than 2 sexual partners.