Deposition of disease-associated prion protein involves the peripheral nervous system in experimental scrapie

There is some evidence that the peripheral nervous system (PNS) is involved in the pathogenesis of transmissible spongiform encephalopathies (TSEs). T he TSE-specific abnormal prion protein (PrPsc) is considered as surrogate m arker for infectivity. We traced the deposition of PrPsc by immunocytochemi stry in sheep and hamsters inoculated intraperitoneally with scrapie. The t rigeminal, dorsal root, celiac, thoracic, and nodose ganglia contained gang lion cells and fewer satellite cells with prominent granular PrPsc depositi on. As a novel deposition pattern, punctate deposits in adaxonal location w ere seen along nerve fibers of peripheral nerve adjacent to ganglia. Such p rominent involvement of the PNS in two different experimental scrapie model s emphasizes the need to consider the PNS in natural scrapie and other TSEs including bovine spongiform encephalopathy as potential source of infectiv ity.