STUDY DESIGN:
The VRC DNA vaccine and VRC recombinant adenoviral vector (rAd5) vaccine have been previously shown to elicit immune responses to HIV-1-specific peptides when administered intramuscularly (IM) alone and in prime-boost schedules. This Phase I, randomized, open-label exploratory study will evaluate the safety and tolerability and the immune responses when IM, subcutaneous (SC) or intradermal (ID) routes of administration are used for the priming vaccinations in a prime-boost schedule. The randomization will ensure that subjects with negative and positive screening adenovirus type 5 antibody (Ad5Ab) titers will be equally represented in each prime-boost schedule evaluated in the study. Group 1 subjects will receive three DNA prime vaccinations followed by a rAd5 boost vaccination and Group 2 subjects will receive one rAd5 prime vaccination followed by a rAd5 boost vaccination. It is also of interest to explore whether vaccination by SC or ID route alters the functional qualities of the immune response. About half of the subjects who screen for HIV vaccine studies at the VRC Clinic have negative Ad5Ab titer and half have positive Ad5Ab titers.
The hypotheses are: 1) IM, SC and ID are all safe routes of administration for both the DNA and rAd5 vaccines; 2) all regimens will elicit immune responses to HIV-1-specific peptides; 3) intradermal administration will allow a lower dosage of the DNA vaccine to be used for eliciting an immune response; and 4) rAd5 booster administered after a rAd5 prime will boost the cellular and humoral immune response. The primary objectives relate to evaluation of the safety and tolerability of the DNA and rAd5 vaccines when administered by IM, SC and ID routes. Secondary objectives are related to evaluation of the immunogenicity of the vaccines when administered by SC and ID routes as compared to the IM route and the social impact of participating in an HIV-1 vaccine trial. Exploratory evaluations of the immunogenicity of the vaccination regimens are also planned.
PROTOCOL DESCRIPTION:
VRC-HIVDNA016-00-VP (DNA vaccine) is composed of 6 closed, circular DNA plasmids that encode HIV-1 Gag, Pol and Nef (from clade B) and Env glycoprotein from clade A, clade B, and clade C; each plasmid comprises 16.67 percent (by weight) of the vaccine. VRC-HIVADV014-00-VP (rAd5 vaccine) is composed of 4 recombinant non-replicating adenoviral vectors that encode for HIV-1 Gag/Pol polyproteins (from clade B) and Env glycoprotein from clade A, clade B, and clade C, which are combined in a 3:1:1:1 ratio, respectively.
SUBJECTS:
Sixty healthy adult volunteers, 18 to 50 years old, 30 subjects with negative Ad5Ab titers (less than 1:12) and 30 subjects with positive Ad5Ab titers (greater than or equal to 1:12).
STUDY PLAN:
Subjects with negative and positive Ad5Ab titers will be equally randomized to the six prime-boost schedules evaluated in the study as shown in the schema below. All injections will be administered by a needle and syringe device appropriate for the route of administration specified.