PRION PROTEIN AND SCRAPIE SUSCEPTIBILITY

This article presents briefly current views on the role of prion prote in (PrP) in Transmissible Spongiform Encephalopathies or prion disease s and the effect of PrP polymoryhisms on the susceptibility to these d iseases, with special emphasis on sheep scrapie, The PrP genotype of s heep apears to be a major risk factor for scrapie, and polymorphisms a t codons 136, 154, and 171 modulate the susceptibility of sheep for sc rapie, Nevertheless, scrapie is not a spontaneous genetic disease alon e, We describe an in vitro system in which sheep PrP variants show cha racteristics which reflect their linkage with in vivo scrapie suscepti bility, Studies with this in vitro system not only confirm that scrapi e susceptibility is determined by the PrP genotype of the target anima l, but also suggest that the PrP genotype of the animal that is the so urce of the infectious agent plays an important role in determining sc rapie susceptibility. The behaviour of PrP variants in this in vitro s ystem mag be an indicator for the transmissibility of prion diseases.