#scrapie

prion diseases

(weirdly interested in the topic^)

(not forced ofc, take as long as you need)

Oh my gosh we would love to! Also first ask let's goooooo!

So prion diseases (also known as transmissible spongiform encephalopathies) are rare neurodegenetive disorders that form in the brain due to the misfolding of the prion protein! It can affect lots of animals, and there are different strains!

Humans commonly (well when I say that I mean that the stats for humans with prion diseases are what we're looking at) get CJD, and some other neurodegenetive diseases such as Parkinson disease form in very similar ways!

The deer family (and also hampsters apparently) commonly get Chronic Wasting Disease! This is a disease that causes excessive drooling, stumbling, loss of agility and general weirdness. CWD can also be called Zombie Deer Disease due to its symptoms!

Cows get Mad Cow Disease, and sheep and I think goats get Scrapie. Humans can contract prion diseases from eating infected meat, but butchers don't sell that meant because prion diseases are deadly.

My personal favourite is Kuru! That's a disease that humans get from eating the brain or spinal cord of another human who already had Kuru! It likely started from a genetic malfunction and is super rare, buuut it's part of the reason why cannibalism is illegal!

But what about scrapie. The sheep version. Where they compulsively scrape up against anything in sight to the point of scraping away their wool.

Imagine that but people

Two sheep flocks in central Alberta have been quarantined by the Canadian Food Inspection Agency (CFIA) for scrapie, a fatal disease that affects the central nervous system of both sheep and goats and is related to mad cow disease.

The CFIA said in mid-June it confirmed a sheep had scrapie, and implemented disease-control measures at that farm. 

It found the diseased sheep had lived on multiple premises, which resulted in a flock at a second farm being quarantined as well.

Microglia Are Key Defenders Against Prion Disease

The findings suggest that drugs that increase the helpful activity of microglia may have a role in slowing the progression of prion diseases.

As for prion research, they started by trying to study scrapie infectivity in mice through the use of sedimentation properties. They didn’t really learn anything for this except that infectivity was spread throughout the entire gradient - i.e. their method of measuring for infective particles didn’t work on scrapie (didn’t separate the infective particles cleanly). Thus, different research methods had to be devised.

In in vitro studies, they tried to inject brains of scrapie-infected sheep into lab mice, but found that it took another 1-2 years of inoculation for the mice to succumb to the disease and become available for data collection. This was too slow for the scientists, but then they discovered that syrian hamsters succumbed much more quickly to the scrapie disease. Thus they began experimenting on syrian hamsters instead for scrapie studies.

They found the phenols, which could hydrolyze or modify proteins, reduced scrapie, but the disease was resistant to treatment methods that altered nucleic acids (UV radiation). Then finally the hypothesis that scrapie was a protein emerged. Thus they coined the term prion, based on how it was proteinaceous and infectious.

PrPSc (Scrapie form of Prion Protein) was identified from the brains of sheep infected by scrapie. They tested portions of sheep brain to see if they were capable of being infected, and they were. The cellular form has superscript C and is not infectious. This prion protein has a molecular mass of 27-30 kiloDaltons and is the protease-resistant core of PrPSc. They managed to sequence the N-terminus of the protein through Edman degradation (way of sequencing where you cleave off amino acids one by one in order to get the correct order). This allowed them to reverse predict the nucleotide sequence and then conduct molecular cloning experiments.