PROJECT SUMMARY The Oregon National Primate Research Center (ONPRC) Expanded SPF (ESPF) Rhesus Macaque Breeding Colony is a highly specialized breeding colony that provides unique and essential macaques with an expanded SPF definition for AIDS research. This colony is critical for AIDS-related opportunistic infection research and vaccine vector development using opportunistic viral agents as vaccine vectors. In order to provide a sufficient number of appropriate animals, the breeding colony must produce 30 surplus animals annually. Concurrently, it is necessary to isolate lymphocryptovirus (LCV) free animals and re-derive LCV-free offspring from LCV seroconverted females in the colony and recruit additional LCV-free infants from Center's conventional SPF colony. A critical shortage of appropriate ESPF social housing severely constrain both our efforts to increase the size of the breeding colony to meet project demand and our endeavors to eliminate LCV from the colony. The application proposes to purchase novel caging and a tunnel to increase the colonies infrastructure for housing multiple cage-housed animals in the ESPF barrier housing facility. Enhancing social housing opportunities will benefit animals with existing behavioral problems, provide better developmental trajectories for infants recruited to the colony, and promote positive animal welfare and health, all while providing an avenue for ESPF population expansion to keep pace with demand. The application also proposes to purchase a storage shed for storing enrichment devices and animals transfer boxes. These items are dedicated for the exclusive support of ESPF macaques to minimize the risk of inadvertently compromising the animals ESPF status.