DETECTION OF SCRAPIE AGENT IN THE PERIPHERAL NERVOUS-SYSTEM OF A DISEASED SHEEP

In an attempt to determine whether scrapie infectivity can be found in the peripheral nervous system of a scrapie-diseased sheep, mice were inoculated intracerebrally or intraperitoneally with 10-fold dilutions of homogenates of Nervus (N.) axillaris, N. ulnaris, N, medianus, N. ischiadicus, N. tibialis, N. fibularis, and N. saphenus. Mice were obs erved for clinical signs of scrapie for 700 days and their brains were analyzed for accumulation of pathological prion protein by immunoblot . Substantial amounts of infectivity were found in all peripheral nerv es tested except N. saphenus. Infectivity at titers of approximately 1 0(4.5) mouse infectious units (MIU)/g were detected in N. axillaris an d N. ischiadicus, of approximately 10(3.0) MIU/g in N. ulnaris, N, med ianus, N. tibialis, and N. fibularis, and of 10(6) MIU/g in the cerebe llum. Since muscles are traversed by the nerve tracts tested, mutton o f scrapie-diseased animals should not be regarded as being free of scr apie agent. (C) 1996 Academic Press, Inc.