- In the 1950s, a disease called kuru was observed among the Fore people of New Guinea that caused trembling, loss of motor control, and ultimately death.
- Kuru and other transmissible spongiform encephalopathies (TSEs) are caused by prion proteins, which are unique infectious proteins that can reproduce on their own and convert normal prion proteins into the abnormal infectious form.
- Prions are extremely resistant to heat and chemicals and can survive in the environment for many years. They infect the central nervous system and cause neurodegeneration through a chain reaction that multiplies copies of the infectious prion protein.
The slides explain history of Prion diseases, proposed mechanisms of pathogenesis, investigations and proposed treatment options. Pl watch after downloading as the slides are mostly animated.
Prepared in June 2014
The slides explain history of Prion diseases, proposed mechanisms of pathogenesis, investigations and proposed treatment options. Pl watch after downloading as the slides are mostly animated.
Prepared in June 2014
This is my report on our cell biology. I hope it could help you.
Objectives: Identify infectious proteins (PrPsc), difference of PrPc and PrPsc, list of neurodegenerative diseases that caused by prions.
Detailed description about viroid, virusoid and prions are described in a simple and detailed manner, will be very to understand about different plant pathogens
A prion is a protein that can fold in multiple, structurally distinct ways, at least one of which is transmissible to other prion proteins. It is this form of replication that leads to disease that is similar to viral infection. The word prion, coined in 1982 by Stanley B. Prusiner, is short for “proteinaceous infectious particle” derived from the words protein and infection, in reference to a prion's ability to self-propagate and transmit its conformation to other prions. While several yeast proteins have been identified as having prionogenic properties, the first prion protein was discovered in mammals and is referred to as the major prion protein (PrP). This infectious agent causes mammalian transmissible spongiform encephalopathies, including bovine spongiform encephalopathy (BSE, also known as "mad cow disease") and scrapie in sheep. In humans, PrP causes Creutzfeldt-Jakob Disease (CJD), variant Creutzfeldt-Jakob Disease (vCJD), Gerstmann–Sträussler–Scheinker syndrome, Fatal Familial Insomnia and kuru.
This is my report on our cell biology. I hope it could help you.
Objectives: Identify infectious proteins (PrPsc), difference of PrPc and PrPsc, list of neurodegenerative diseases that caused by prions.
Detailed description about viroid, virusoid and prions are described in a simple and detailed manner, will be very to understand about different plant pathogens
A prion is a protein that can fold in multiple, structurally distinct ways, at least one of which is transmissible to other prion proteins. It is this form of replication that leads to disease that is similar to viral infection. The word prion, coined in 1982 by Stanley B. Prusiner, is short for “proteinaceous infectious particle” derived from the words protein and infection, in reference to a prion's ability to self-propagate and transmit its conformation to other prions. While several yeast proteins have been identified as having prionogenic properties, the first prion protein was discovered in mammals and is referred to as the major prion protein (PrP). This infectious agent causes mammalian transmissible spongiform encephalopathies, including bovine spongiform encephalopathy (BSE, also known as "mad cow disease") and scrapie in sheep. In humans, PrP causes Creutzfeldt-Jakob Disease (CJD), variant Creutzfeldt-Jakob Disease (vCJD), Gerstmann–Sträussler–Scheinker syndrome, Fatal Familial Insomnia and kuru.
PRIONS-structure, multiplication, diseases.pptxRASHMI M G
PRIONS are infectious agents composed primarily of sialoglycoprotein.
This protein is called prion protein (PrP)
They contain no nucleic acid.
They cause a variety of neurodegenerative diseases in humans and animals.
According to STANLEY PRUSINER,
Prions- ‘which means proteinaceous and infectious (-on by analogy to virion) that lacks nucleic acid’.
It refers to a previously undescribed form of infection due to protein misfolding . While the infectious agent was named prion, and the specific protein that make the prion was named PrP i.e. ‘protease resistant protein’.
PRIONS proteins in the form of fibres which also occur as fold rods.
The normal protein found in a variety of tissues is referred to as PrPC (C refers to cellular or common PrP), whereas the misfolded form of PrPC is called PrPSc which is responsible for the formation of amyloid plaques that results in neurodegeneration.
PrPSc is the infectious form of PrPC, (Sc refers to scrapie, a prion disease occurring in sheep) .
PrPc is a Alpha helical while PrPSc is a beta pleated sheet
PrPc do not contain beta sheet.
PrPc protein can adopt 2 distinct different stable conformations.
All known prions induce the formation of an amyloid fold in which the protein polymerizes into an aggregate consisting of tightly packed beta sheets.
This altered structure is extremely stable and accumulates in the infected tissue causing cell death and tissue damage resulting in death of animals.
It is supposed that the diseased form of PRION (PrPSc) originated spontaneously or transmitted through ingestion of food/feed directly interacts with the normal endogenous form PrPC and enables to rearrange its structure.
As a result of interaction the normal form PrPC is converted to abnormal form (PrPSc) .
It is assumed that an unidentified cellular protein (protein X) helps the conversion of PrPC to PrPSc by bringing a molecule of each of the two together into a complex.
Main reason for the cause of prions is ‘cannibalism’ i.e. eating of one human by another human.
2 types of cannibalism – endocannibalism (eating humans from the same community) and exocannibalism ( eating humans from other communities).
The tribal ground up the brain into a pale grey soup, heated it and ate it.
Therefore, ingestion of brain tissue of dead relatives for religious reasons was likely the route of transmission.
In cattles
-BOVINE SPONGIFORM ENCEPHALOPATHY
(mad cow disease).
2. In humans
-ALZHEIMER’S DISEASE
DOWN’S SYNDROME
FATAL FAMILIAL INSOMNIA
KURU LEPROSY
Misfolded proteins which catalyses the refolding of the native protein into the misfolded pathogenic forms are called as Prions. They are responsible for fatal neurodegenerative diseases. Some of the neurodegenerative diseases such as Scrapie, BSE, CWD of animals and Kuru, CJD, Fatal familial insomnia of human beings are included in the presentation.
Kuru is very rare disease. Kuru is found among people from New Guinea who practiced a form of cannibalism in which they ate the brains of dead people as part of a funeral ritual.
Prion Diseases ; An overview .........
Credit goes equally to Dr Siraj Uddin, M.V.Sc Scholar, IVRI and Dr. Gazanfar Abass, M.V.Sc. Scholar, VPH, IVRI.
For Further reference contact at gazanfar0966@gmail.com
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Prions
1.
2. In the 1950s, a district medical
officer working in the highlands
of New Guinea observed a fatal
disease among the people of the
Fore (FOR-ay) tribe. The Fore
people called this sickness kuru,
which means "trembling in fear."
After intially becoming unable to
walk, victims of kuru lost the
ability to swallow or chew. Drastic
weight loss would inevitably lead
to death. Today we know that
kuru is one of several diseases in
humans and animals caused by
prion (PREE-on) proteins.
The Mystery of Kuru
3. Introduction to Prions
- Pronounced “pree-on”
- Shortened term for:
Proteinaceous Infections Particle
- Causes TSE (Transmissible Spongiform Disease)
which attacks the central nervous system (the
brain).
4. Basic Structure
Normal prions
contain about
200-250 amino
acids twisted into
three telephone
chord-like coils
known as helices,
with tails of more
amino acids.
5. Basic Structure
The mutated, and
infectious, form is
built from the same
amino acids but
take a different
shape.
100 times smaller
than the smallest
known virus.
Normal Mutated
7. Differences From Bacteria &
Viruses
Prions do not contain nucleic acid; they don’t have
DNA or RNA.
They are extremely resistant to heat and chemicals.
Prions are very difficult to decompose biologically;
they survive in soil for many years.
8.
9. Prions (PREE-ons) are
proteins that are unique
in their ability to
reproduce on their own
and become infectious.
They can occur in two
forms called PrP-sen and
PrP-res.
10.
11. Both PrP-sen and PrP-res are made up of the exact
same string of amino acids, the building blocks that
make up proteins. However, the two forms have
different shapes.
PrP-sen is produced by normal healthy cells. The sen
stands for “sensitive” because this version of the
protein is sensitive to being broken down.
PrP-sen is present mainly in neurons in the brain, but
is also found in other cell types.
12. Scientists don’t know the exact function of PrP-sen,
but there is evidence that it may be involved in
communication between neurons, cell death, and
controlling sleep patterns. Interestingly, mice that are
genetically engineered to produce no PrP-sen seem to
be healthy.
The second type of prion protein, known as PrP-res, is
the disease-causing form. Organisms with it develop
spongiform disease. “res” stands for “resistant” because
this version of PrP is resistant to being broken down.
13. Unlike other infectious agents, prions do not contain
genetic material. However, once they infect an
individual, prions can replicate. How is this possible?
Scientists are still working out the details, but evidence
supports the idea that when PrP-sen comes into
contact with PrP-res it is converted to PrP-res. The
result is a chain reaction that multiplies copy after
copy of the infectious prion.
Because of their abnormal shape, PrP-res proteins
tend to stick to each other. Over time, the PrP-res
molecules stack up to form long chains called
“amyloid fibers”.
14. Amyloid fibers are toxic to cells, and ultimately kill
them.
Cells called astrocytes crawl through the brain
digesting the dead neurons, leaving holes where
neurons used to be. The amyloid fibers remain.
19. 1950s
High levels of kuru
appear among the Fore
people of New Guinea.
1960s
Scientists
experimentally transmit
Kuru and CJD to
chimpanzees,
demonstrating the
transmissible nature of
these diseases.
20. 1980s
60 people die from
CJD after being
infected by
contaminated
surgical
instruments. 85
people die after
receiving prion-
infected growth
hormone injections.
21. 1982
Dr. Stanley Prusiner
coins the term
"prion"
(PROteinaceous
INfectious particle).
Highly purified
PrP-res is shown to
be infectious. He
goes on to win the
Nobel Prize in
Medicine in 1997.
25. Classic CJD or Creutzfeldt-Jakob disease (human)
The most prevalent of the spongiform diseases
Occurs spontaneously in 1 out of a million people
10% of cases are inherited mutations in the PRPN gene
Usually strikes people age 50 to 75
Symptoms: dementia, muscle twitching, vision
problems
Fatal Familial Insomnia (human)
All cases are inherited mutations in the PrP
gene
Usually strikes people age 36 to 61
Disruption of sleep/wake cycle leads to
coma, then death
Scrapie (goats, sheep)
Occurs as infection in genetically susceptible
sheep
There is no evidence of spread to humans
26. BSE or Bovine Spongiform
Encephalopathy (cattle)
Also known as "Mad Cow Disease" because
infected animals act strangely and can be
aggressive
Spread rapidly through Britain by rendering
Chronic Wasting Disease (deer, elk)
Infectious disease in wild deer and elk
primarily in the western United States
Drooling, difficulty swallowing, weight loss
Kuru (human)
Struck members of the Fore tribe in the
1950s and 1960s
Muscle weakness, loss of coordination,
tremors, inappropriate episodes of laughter
or crying
Transmitted by ritual cannibalism as part of
funeral ceremonies
27.
28. Controversy
DNA and RNA are the only substances now known
to replicate in body tissues, so how do prions make
copies of themselves without any nucleic acids?
Some believe TSEs are caused by an unidentified
slow-acting virus.
Others believe a small virus accompanies a prion
and they work together to cause disease.