Abstract
Although scrapie has been studied for many years, its pathogenesis is still poorly understood. It has not been possible to demonstrate any immune response to the scrapie agent, and it is not known if immune mechanisms play any role in defence against scrapie infection (Gibbs, Gajdusek & Morris, 1965; Clarke & Haig, 1966). It has been suggested that the disease caused by the scrapie agent may be analogous to experimental allergic encephalomyelitis (EAE), and that an immune response may actually cause the observed pathological lesions (Paterson et al. 1966). Because of this uncertainty about the role of the immune system in scrapie, experiments were undertaken to determine the effect of long-term immuno-suppression with cyclophosphamide (Cytoxan) on the outcome of scrapie infection in the mouse.
Cytoxan was obtained from Mead Johnson and a solution in phosphate buffered saline at a concentration of 20 mg./ml. was prepared just before use. A titrated pool of the scrapie agent in mouse brains was obtained from Dr C. J. Gibbs, Jun. at the National Institutes of Health; this strain was originally obtained from a sheep and was subsequently passaged in goats in England.
* Present address: Department of Biological Structure, University of Miami School of Medicine, Miami, Florida.