The purpose of this proposal is to continue to provide essential professional staff and laboratory resources specifically designed for the investigation of the naturally occurring diseases of research animals at the John Hopkins University and affiliated institutions. The major function of these laboratories is to provide diagnostic support in outbreaks of naturally occurring diseases in the 25,000 to 30,000 animals present daily and to develop and implement procedures to prevent and control disease outbreaks. The personnel and laboratories also carry on the important role of preventive medicine both in order to minimize introduction of diseased animals into the Hopkins facilities, and to monitor animal sources.