Infection with HIV, SIV, and administration of vaccines based upon their components, elicit specific humoral and cellular immune responses. The quantitation of these responses, and the identification of antigenic epitopes recognized by specific effector mechanisms, are crucial to the success of the projects described in this PO1. The overall objective of the Immunology Core is to provide comprehensive immunologic services, reagents, and facilities to members of ADARC, thereby facilitating evaluation of the immunological properties of candidate vaccines.