Abstract
Prions are an enigma amongst infectious disease agents as they lack a genome yet confer specific pathologies thought to be dictated mainly, if not solely, by the conformation of the disease form of the prion protein (PrPSc). Prion diseases affect humans and animals, the latter including the food-producing ruminant species cattle, sheep, goats and deer. Importantly, it has been shown that the disease agent of bovine spongiform encephalopathy (BSE) is zoonotic, causing variant Creutzfeldt Jakob disease (vCJD) in humans. Current diagnostic tests can distinguish different prion types and in food-producing animals these focus on the differentiation of BSE from the non-zoonotic agents. Whilst BSE cases are now rare, atypical forms of both scrapie and BSE have been reported, as well as two types of chronic wasting disease (CWD) in cervids. Typing of animal prion isolates remains an important aspect of prion diagnosis and is now becoming more focused on identifying the range of prion types that are present in food-producing animals and also developing tests that can screen for emerging, novel prion diseases. Here, we review prion typing methodologies in light of current and emerging prion types in food-producing animals.
Highlights
It was noted that on western blots the glycoform pattern of the PrPSc-res triplet bands could be indicative of prion type, for instance with bovine and ovine bovine spongiform encephalopathy (BSE) displaying a dominant diglycan compared to classical scrapie [79]
Whilst the cases of BSE in ruminants is very low and the associated concern for the contamination of the human food chain with the zoonotic BSE agent has eased, there are still concerns surrounding the exposure of humans to prions from food-producing animals
The more recent description of atypical/Nor98 scrapie in goats/sheep and atypical bovine BSE as well as the discovery of two distinct types of chronic wasting disease (CWD) all raise the possibility that further types of prions are circulating in ruminants that are not detected and/or defined by current assay methods
Summary
It is thought that PrPSc is responsible for the conversion of additional molecules of PrPC into PrPSc and that this is the central molecular event that occurs during TSE disease. This conversion event is largely restricted to those cells of the lymphoreticular tissues (LRS) and central nervous system (CNS), and the end product has a propensity to aggregate and form amyloid. It is thought that either this PrPSc end product, or a conformer of this protein formed along the folding pathway is toxic to cells of the CNS and is responsible for the characteristic brain pathology including the spongiosis, astrocytosis and neuronal loss that are commonly associated with these diseases
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
