Transmissible spongiform encephalopathies are an uncommon group of neurodegenerative disorders that can impact both animals and humans. They are induced by abnormally folded proteins in the brain, particularly prion protein misfolding.
This causes a gradual decline in brain function, resulting in changes in memory, behavior, and movement. Transmissible spongiform encephalopathies are ultimately fatal. In the US, approximately 300 cases of TSEs are reported each year.
Misfolded PrP can connect to healthy PrP in people with transmissible spongiform encephalopathies, causing the healthy protein to fold abnormally as well. Misfolded PrP starts to build up and form clumps within the brain, causing nerve cells to be damaged and killed. Under a microscope, this damage induces tiny holes to form in brain tissue, giving it a sponge-like appearance.