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 convention 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 complete modifications of the existing southwest outdoor sheltered housing structure providing an additional four 500 sq. ft. social housing units. The proposed modifications would expand the total number of outdoor ESPF breeding animals housed in social groups permitting increased production, facilitate genetic management by providing smaller housing units that are more appropriate for housing 7-10 females and a male and offspring, provide sufficient separation between individual housing units to prevent transmission of agents between groups, and improve animal welfare through social housing.