Transcript Prions - Mount Mansfield Union High School

Sly Richards
The first cases of transmissible spongiform
encephalopathies were reported in Great
Britain in the 1700’s.
The first case was documented in sheep and is
called Scrapie.
In the 1970’s, the prion disease was widely
recognized in Papua New Guinea and was
called Kuru.
 A prion is an infectious agent in the form of a misfolded protein.
 Prions are different compared to other infectious agents.
 They have no genetic material and they are smaller than viruses.
 They are not alive.
 Prions are responsible for neurodegenerative spongiform
encephalopathies.
 10% of prion diseases are hereditary and the other 90% are
contracted or sporadic.
 Prion disease is contracted by consuming contaminated meat.
 All prion diseases are neurodegenerative and lethal.
 All prion diseases have an incubation period but it can range from
weeks to years depending on the spread rate of the prions.
In every organism, there is a protein in the
body that scientists believe prions originate
from. This protein can misfold and become a
prion.
When a prion enters a healthy organism, it
travels to the brain where the preexisting
prion proteins reside and when it touches one
of them, that protein becomes a prion, and a
chain reaction occurs.
 There are three different ways that a species can
contract prions: acquired, inherited, or sporadic.
 The primary transmission method in animals is
acquired by ingestion. When an animal dies of a prion
disease, other animals can eat it or prions can linger on
particles of dirt. If it is in a nearby water source it
could contaminate that.
 Infection can occur from manure and since manure can
be near reservoir areas it can leak into the water
supply and contaminate it.
 Prions can also bind to airborne particles and travel
large distances.
Sterilization of prions is extremely difficult
because of their extremely stable structure.
Prions are resistant to all normal methods of
sterilization.
Effective sterilization relies upon protein
hydrolysis, reduction, or destruction of the
protein tertiary structure.
Bleach, caustic soda, or strong acidic
detergents can be used to destroy prions.
PrPc is a normal protein found throughout
the body.
PrPsc is the infectious form of the protein
 When it touches the normal protein, the normal
protein transforms into the infectious protein
which starts a chain reaction.
 A group of prions starts forming which causes
the neuro-degeneration and eventual death.
The Affected species
Disease
Sheep, Goat
Scrapie
Cattle
Bovine Spongiform Encephalopathy (AKA
Mad Cow Disease)
Mink
Transmissible Mink Encephalopathy
White Tailed Deer, elk, mule, moose
Chronic Wasting disease
Cat
Feline Spongiform Encephalopathy
Nyala, oryx, Kudu
Exotic Ungulate Encephalopathy
Ostrich
Spongiform Encephalopathy
Human
Creutzfeldt-Jakob Disease
The name scrapie come from one of the
symptoms of the disease. Animals will
compulsively scrape against anything they can
find which causes rashes and bare spots on
the fleece.
Other symptoms are excessive smacking of
lips, strange walking patterns, and convulsive
collapsing.
When a prion infects cattle, it will cause a
change in behavior, uncoordinated
movements, trouble standing and walking,
weight loss despite an appetite, and
decreased milk production.
 Eventually the cow dies.
In Europe, there used to be a program called
MBM which stood for meat and bone meal.
 European farmers used to feed cattle the ground
up remains of other cattle
 some of those would be infected and that was
how an epizootic occurred.
TME is a rare disease that affects only adult
mink and usually only occurs in ranch-raised
mink.
The symptoms of this disease are behavioral
changes, loss of cleanliness, aimless circling,
weight loss, matted fur, hind quarter ataxia,
and seizures rarely occur.
This causes cervids (the deer family) to slowly
lose weight and eventually die.
The symptoms include decreased interactions
with other animals, listlessness, lowering of
the head, blank facial expression, repetitive
walking in set patterns, and a smell like rotten
flesh.
This disease effects the brains and liver of
cats. It symptoms include behavioral changes
and ataxia.
This affects exotic zoo animals. This prion
infectious disease was spread when these
animals were fed supplemented meat and
bone meal.
Ostrich can contract this disease, but once
they contract it, it has been theorized that the
disease is not transmissible.
This form of prion disease affects humans.
Symptoms
 Dementia followed by memory loss, personality
changes, hallucinations, speech impairment, jerky
movements, balance and coordination
dysfunction, changes in gait, rigid posture, and
seizures.
Kuru is a Prion disease that was noticed in
Papua new Guinea.
It was transferred throughout the tribe via
cannibalism.
Classic symptoms involved tremorsand
sporadic laughing.