This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. Introduction. Nonhuman primates used in biomedical research can be provided the best quality of life if their management takes their disease status into consideration. For example, it is important to understand how to best meet the social needs of primates throughout the progression of simian AIDS. This study aims to 1) characterize the changes in psychological wellbeing associated with simian immunodeficiency virus disease progression, 2) determine the correspondence between measures of wellbeing and disease-related changes in physiology, and 3) identify any threshold behavioral or physiological values that should be used to trigger either increased scrutiny of compatibility or alterations in the social setting of research subjects. Methods. Subjects include adult, Indian-origin rhesus macaques assigned to research protocols involving SIV infection and anticipated development of SIV disease (i.e. not subject to vaccines, other prophylactic measures, or experimental treatments). The total number of subjects studied will be 32 of each sex. Using behavioral, physiological, immunological and clinical data, changes within individuals are assessed. In addition, effects of pair- versus single housing is being compared . Data collection begins prior to social introduction and SIV inoculation in order to document baseline profiles in single housing, and is repeated after introduction into pair housing and prior to infection. Within pairs, both members are inoculated on the same day. After inoculation, data are collected intensively for the first month. After the first month, a steady scheduling of less intensive data collection is followed until the endpoints approved by the Animal Care and Use Committee are reached. Results/Discussion. Data collection has been initiated for 24 subjects, all of whom have been infected to date but none of whom have reached study endpoints. Data analysis for each individual will commense after an individual is euthanized.