Methods for Differentiating Prion Types in Food-Producing Animals

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.

An Overview of Prion Diseases: Protein Transformation, Effects on Animals, and Current Treatments

“…In humans, the symptoms of prion diseases are quite similar to the ones observed in animals. In addition, other symptoms observed in humans such as intellectual and memory loss, muscle atrophy, and increasing loss of brain function were also observed in prion diseases in animals (Gough, 2015).…”

Conventional and State-of-the-Art Detection Methods of Bovine Spongiform Encephalopathy (BSE)

“…Some studies have identified a larger molecular mass of the unglycosylated band of PrP res in sheep with natural scrapie than in experimentally BSE-infected sheep ( Figure 5 ). An unglycosylated band of PrP res in BSE sheep is approximately 1.6 kDa smaller than in sheep scrapie [ 6 , 21 , 53 , 77 , 78 , 79 , 80 , 81 ]. Unfortunately, the unglycosylated fraction represents only 5–20% of total PrP res , and the unglycosylated band can be very faint or invisible, making this approach less attractive for routine diagnosis.…”

“…The P4 antibody that recognizes the N-terminal end of the protein binds well only to PrP res in scrapie and almost not at all to PrP res in sheep with BSE. In contrast, monoclonal antibodies 6H4, 66.94b4, 505, 8G8, and R521, recognize the core region, and bind PrP res in samples from both BSE- and scrapie-infected sheep; thus, WB with double antibody discrimination can easily distinguish BSE and scrapie [ 6 , 8 , 75 , 79 ]. Furthermore, the ratio of P4/core antibody is significantly higher for scrapie than for BSE [ 16 , 53 , 78 , 82 ].…”

“…Therefore, it has been proposed that due to the high variability between blots, glycoform profiles should be obtained from repeated examination of samples across multiple blots using photo-imaging techniques to quantify band intensities. The inclusion of appropriate controls on each gel is also important in aiding the differentiation of the BSE in sheep samples [ 78 , 79 ].…”

Encefalopatia Espongiforme Bovina - Revisão De Literatura

“…O príon (PrPc), quando é mal dobrado, ele perde sua função e se torna PrPSc, que é o príon patogênico. Quando patogênico, ele deixa suas funções fisiológicas de lado e se torna tóxico para as células do sistema nervoso central (SNC), tendo como consequência patologias cerebrais características incluindo: espongiose no cérebro, astrocitose e também uma perda neuronal, ambas associadas a essas doenças (GOUGH et al, 2015).…”