The mouse model for scrapie: inoculation, clinical scoring, and histopathological techniques

Transmission to mice and other laboratory rodents are central to the study of prion diseases. Bioassays are essential for testing the presence of infectivity, as well as for titration and strain typing studies. Given the peculiar nature of prions, their characterization relies mainly on the measurement of the length of the incubation period in inoculated mice and on the study of a number of parameters, such as the clinical manifestations, the type of pathological changes and the biochemical characteristics of PrP(Sc), that call for considerable experience and care in the execution of laboratory procedures and in the reading and interpretation of results. Researchers who are new to the prion field or who would like to expand into studies of rodent models may need information about the practical aspects of prion diseases in mice. This chapter reviews the techniques used in transmission studies, from the preparation of the inocula to pathological investigations, with specific focus on the potential problems that may occur and how to solve them.