Transmissible spongif orm encephalopathies

Transmissible spongiform encephalopathies (TSEs, also called Prion diseases) are fatal neurodegenerative diseases such as scrapie of sheep, Creutzfeldt-Jakob disease (CJD) of humans, bovine spongiform encephalopathy (mad cow disease) and chronic wasting disease (CWD) of deer and elk. Bovine Spongiform Encephalopathy is thought to be the cause of variant Creutzfeldt Jakob Disease (vCJD) which is a neurological disease different from CJD, leading to death in humans. TSEs are caused by accumulation of prion protein, an abnormal form of protein found in humans and animals. Normal prion protein is expressed in a wide variety of tissues, but conversion of normal prion protein to the TSE form appears to be restricted primarily to cells of the nervous and lymphoid systems. In order to determine why some cell types are more resistant to TSE infection than others, scientists developed a tissue culture system that allows them to monitor both acute and persistent abnormal prion protein (PrP- res) formation. It has been demonstrated that while any cell type can make new PrP- res following exposure to TSE infectivity, only some cell types go on to become chronically infected and make PrP-res persistently. This suggests that there are cell- specific factors that determine the susceptibility of a cell to chronic TSE infection. These factors, once identified, could be useful in designing effective anti-TSE therapeutics.