Safety of and Immune Response to Two Different HIV Vaccines, Each Followed by a Adenoviral Vaccine Boost, in HIV Uninfected Adults

Inclusion Criteria: * HIV uninfected * Good general health * Pre-existing adenovirus 5 (Ad5) neutralizing antibody titers of less than a 1:12 ratio * Hepatitis B surface antigen negative * Anti-hepatitis C virus (anti-HCV) antibody negative or negative HCV PCR if anti-HCV antibody is positive * 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 forms of contraception 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 120 days prior to first study vaccination * Live attenuated vaccines within 30 days prior to first study vaccination * Investigational research agents within 30 days prior to first study vaccination * Medically indicated subunit or killed vaccines within 14 days prior to first study vaccination * Current anti-tuberculosis (TB) preventive therapy or treatment * Clinically significant medical condition, abnormal physical exam findings, abnormal laboratory results, or past medical history that may affect current health. More information about this criterion can be found in the protocol. * Any medical, psychiatric, or social condition that would interfere with the study. More information about this criterion can be found in the protocol. * Any job-related responsibility that would interfere with the study * Serious adverse reactions to vaccines, including hypersensitivity and related symptoms. A person who had an adverse reaction to pertussis vaccine as a child is not excluded. * Autoimmune disease or immunodeficiency * Active syphilis infection. Participants who have been fully treated for syphilis for more than 6 months prior to study entry are not excluded. * Moderate to severe asthma. More information on this criterion can be found in the protocol. * Type 1 or type 2 diabetes mellitus. Participants with histories of isolated gestational diabetes are not excluded. * Thyroid disease or surgical removal of the thyroid requiring medication during the 12 months prior to study entry * Accumulation of fluid in the blood vessels (angioedema) within 3 years prior to study entry if episodes are considered serious or have required medication in the 2 years prior to study entry * Uncontrolled hypertension * Body mass index (BMI) of 40 or greater OR BMI of 35 or greater if certain other criteria apply. More information about these criteria can be found in the protocol. * Bleeding disorder * Cancer. Participants with surgically removed cancer that is unlikely to recur are not excluded. * Seizure disorder * Absence of the spleen * Mental illness that would interfere with the study * Pregnancy or breastfeeding