A Multicenter, Randomized, Placebo-Controlled, Double-Blind Trial to Evaluate the Safety and Immunogenicity of the Therion Recombinant Vaccinia-HIV-1 IIIB ENV/GAG/POL Vaccine (TCB-3B) and MN RGP 120/HIV-1 In Alum.

To evaluate the safety of administering Therion Recombinant Vaccinia-HIV-1 IIIB env/gag/pol Vaccine (TBC-3B) vaccinations to vaccinia-naive individuals. To evaluate the immunogenicity of priming with TBC-3B by the scarification, intradermal, and subcutaneous routes, followed by booster immunization of MN rgp120 HIV-1. To compare the immunogenicity of priming with TBC-3B in vaccinia-naive individuals to vaccinia-immune individuals. In prior trials evaluating alternative methods of vaccine administration, scarification has been found to be an imprecise method of administration and allows only 1.0 - 2.5 microliters of immunogen to be given. Since it is not feasible to produce vaccine at concentrations higher than 10 to the 10th pfu/ml, this method limits the maximum deliverable dose. Intradermal and subcutaneous injection routes allow larger volumes of vaccinia to be given, i.e.: up to 200 microliters intradermally and up to 100 ml subcutaneously. In the present study, the initial priming dose will be the same administered by all 3 methods; however, the second priming dose administered at 2 months intradermally and subcutaneously will be 2 logs higher in order to achieve boosting of immune responses, particularly to gag and pol components of TBC-3B. In prior trials evaluating alternative methods of vaccine administration, scarification has been found to be an imprecise method of administration and allows only 1.0 - 2.5 microliters of immunogen to be given. Since it is not feasible to produce vaccine at concentrations higher than 10 to the 10th pfu/ml, this method limits the maximum deliverable dose. Intradermal and subcutaneous injection routes allow larger volumes of vaccinia to be given, i.e.: up to 200 microliters intradermally and up to 100 ml subcutaneously. In the present study, the initial priming dose will be the same administered by all 3 methods; however, the second priming dose administered at 2 months intradermally and subcutaneously will be 2 logs higher in order to achieve boosting of immune responses, particularly to gag and pol components of TBC-3B. After volunteers are recruited, screened and enrolled in the study, they will be randomized to group C, D, or E. Each group will enroll 10 patients and 2 controls. The placebo control for TBC-3B will be standard vaccinia vaccination administered at doses no higher than that administered by scarification; the placebo control for MN rgp120 will be alum. Group C will receive undiluted TBC-3B by scarification, at months 0 and 2. Group D will receive diluted TBC-3B intradermally at month 0 and undiluted TBC-3B at month 2. Group E will receive diluted TBC-3B subcutaneously at month 0 and undiluted TBC-3B at month 2. At months 8 and 12 all groups will receive MN rgp 120/HIV-1 in alum intramuscularly.