Safety and Immune Response to Preventive HIV Immunization With Adenovirus Serotype 5 or 35 Vector

Inclusion Criteria: * Good general health * Access to a participating HVTN clinical research site and willingness to be followed for the duration of the study * Assessment of understanding, including understanding of Step Study results * Willing to receive HIV test results * Willing to discuss HIV infection risks, agree to HIV risk reduction counseling, and willing to continue 5 years of annual follow-up contact * Willing to commit to maintaining behavior consistent with low risk of HIV exposure through the last required protocol visit * Considered low risk for HIV infection after clinical staff assessment. More information on this criterion can be found in the protocol. * Certain laboratory values. More information on this criterion can be found in the protocol. * Negative Hepatitis B surface antigen * Negative anti-Hepatitis C virus antibodies * For females, agree to use effective contraception from at least 21 days prior to enrollment through the last protocol visit. More information on this criterion can be found in the protocol. Exclusion Criteria: * HIV-infected * Active drug or alcohol abuse within 12 months prior to study entry * History of newly acquired sexually transmitted infections. More information on this criterion can be found in the protocol. * Experimental vaccines received within 5 years prior to study entry * Immunosuppressive medications received within 168 days prior to first vaccination * Blood products received within 120 days prior to first vaccina…