Summary: The goal of this project is to maintain and enhance the specific pathogen free (SPF) pigtail macaque (M. nemestrina) breeding colony at the Washington National Primate Research Center (WaNPRC). This colony is the only major domestic breeding colony of M. nemestrina and the primary source of this important animal model for AIDS studies and other types of biomedical research in the United States. M. nemestrina have unique immunological, genetic, behavioral, anatomical, and physiological characteristics that make them an essential model in a number of areas of research related to HIV/AIDS. Specific pathogens (SIV, SRV, STLV-1, McHV-1) are a threat to animal or human health, or interfere with research and must be excluded to optimize nonhuman primate research models. In this proposal we discuss how we will maintain the WaNPRC SPF M. nemestrina breeding colony to provide animals of the highest quality to meet research needs. The SPF colony is housed at two locations, the Arizona Breeding Colony (ABC) which is an integral part of the WaNPRC, and at the New Iberia Research Center (NIRC). Having animals at two sites raises some challenges, but provides for contingencies in case of adverse events, and we have established lines of communication to ensure consistency. At both sites we will use innovative bioinformatics tools to increase cost effectiveness by maximizing production per animal. In addition, in our Seattle Infant Primate Research Laboratory (IPRL) we will initiate breeding for the production of expanded SPF M. nemestrina, which will be free of simian foamy virus (SFV), cytomegalovirus (MnCMV), rhadinovirus (MnRV), and simian varicella (SVV). Viral exclusion testing for all present and future excluded viruses will be performed by the Primate Diagnostic Services Laboratory (PDSL) through the virology core. We will use state-of-the-art genomics to characterize the animals, focusing on expressed alleles in the MHC region through the MHC Genetic Typing Core.