Scrapie: Deciphering its pathophysiology and cause

Scrapie belongs to a group of fatal neurodegenerative diseases known as tra nsmissible spongiform encephalopathies. Molecular research into the cellula r pathophysiology of scrapie has identified the presence of a normal glycop rotein (PrPC) and an abnormal form (PrPSC) within neurons of affected sheep . The rate and ability of PrPC to be converted into PrPSC is dependent on t he genetic susceptibility unique to each breed of sheep. Three codon positi ons (136, 154, and 171) determine genetic susceptibility. The combination o f amino acids that-occurs at these loci conveys resistance to scrapie infec tions and influences incubation periods.