A Worldwide, Phase I, Dose-Escalating Study of a 3-Dose Regimen of the MRKAd5 (Clade B) Vaccine in Healthy Adults (V520-018)

A Worldwide, Phase I, Dose-Escalating Study of Safety, Tolerability, and Immunogenicity of a 3-Dose Regimen of the MRKAd5 HIV-1 Gag Vaccine in Healthy Adults

This three stage study will evaluate the safety and tolerability of MRKAd5 HIV-1 Gag Vaccine. In Stage I subjects will be randomized to receive the vaccine at 1x10^9 viral particles/dose (vp/d) or placebo. In Stage II subjects will be randomized to receive the vaccine at 1x10^10 vp/d or placebo. In Stage III subjects will be randomized to receive the vaccine at 1x10^9 vp/d, at 1x10^10 vp/d, or placebo. Immunogenicity of the single dose regimen of MRKAd5 HIV-1 Gag Vaccine will also be measured.

Inclusion Criteria:

• Subject is in good general health
• Subject tests negative for Hepatitis B, Hepatitis C, and HIV
• Subjects of reproductive potential agree to use an accepted method of birth control through the entire study

Exclusion Criteria:

• Subject has a recent history of fever at time of vaccination
• Subject has received immune globulin or blood product 3 months prior to injection
• Subject has been vaccinated with live virus vaccine 30 days prior to receipt of first dose
• Subject has been vaccinated with inactivated vaccine with 14 days prior to receipt of first dose
• Subject has a chronic medical condition that is considered progressive
• Subject has history of malignancy
• Subject weighs less than 105 lb.
• Female subject is pregnant or breast feeding, Male subject is planning to impregnate during the first year of study
• Subject has contraindication to intramuscular injection
• Subject is unlikely or unwilling to adhere to lower risk sex practices during the course of the study
• Subject has a tattoo on the deltoid region of the arm or the injection of Depo-Provera