Abstract
Characterization of the microbiological status is an important facet of a quality assurance program for laboratory animals. This paper addresses basic issues with regard to standardization of the characterization of murine viral status. Methods for such characterization include clinical signs, virus isolation, and serological tests. Significant considerations are screening profiles; sample collection, processing, and shipment; and sampling schedules. International standardization of programs and methods to control and characterize the microbiological status of laboratory animals is being developed, and will be highly significant in future efforts to produce, control, and maintain laboratory animals free of viral infections.