A Phase 1B Open-label Clinical Trial to Expand the Characterization of the Immune Responses to the Merck Adenovirus Serotype 5 HIV-1 Gag/Pol/Nef Vaccine in Healthy, HIV-1-uninfected Adult Participants

Note: As of 09/19/07, enrollment and vaccinations have been discontinued.

Inclusion Criteria:

- Good general health

- HIV uninfected

- Weight of 110 pounds or greater

- Have access to a participating HIV Vaccine Trials Unit (HVTU) and are willing to be
followed during the study

- Willing to receive HIV test results

- Understand the vaccination procedure

- Willing to use acceptable methods of contraception for at least 21 days prior to
study entry and until the last study visit

Exclusion Criteria:

- HIV vaccines or placebos in prior HIV trial. Participants who can provide
documentation that they received a placebo in a prior HIV trial may be eligible.

- Immunosuppressive medications within 168 days prior to first study vaccination

- Blood products within 90 days prior to first study vaccination or within 14 days
after the injection

- Immunoglobulin within 90 days prior to first study vaccination or within 14 days
after the injection

- Live attenuated vaccines within 42 days prior to first study vaccination or within 14
days after the injection

- Investigational research agents within 30 days prior to first study vaccination

- Medically indicated subunit or killed vaccines within 5 days prior to first study
vaccination or within 14 days after the injection

- Allergy treatment with antigen injections within 30 days prior to first study
vaccination

- Clinically significant medical condition, abnormal physical exam findings, abnormal
laboratory results, or past medical history that may affect current health

- Any medical, psychiatric, or social condition that, in the opinion of the
investigator, would interfere with the study.

- History of anaphylaxis and/or allergy to vaccine components

- Autoimmune disease or immunodeficiency

- Uncontrolled hypertension

- Bleeding disorder

- Cancer. Participants with surgically removed cancer that is unlikely to recur are not
excluded.

- Seizure disorder

- Absence of the spleen

- Abnormal laboratory values

- Mental illness that would interfere with the study

- Hysterectomy

- Pregnancy or breastfeeding