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Questions and Answers
What is the estimated cost of Bovine Spongiform Encephalopathy (BSE) to the Canadian cattle industry?
What is the estimated cost of Bovine Spongiform Encephalopathy (BSE) to the Canadian cattle industry?
Which genotype is associated with high susceptibility to scrapie?
Which genotype is associated with high susceptibility to scrapie?
How long can scrapie infectivity persist in the environment?
How long can scrapie infectivity persist in the environment?
What is a key factor in the control of scrapie according to Canadian regulations?
What is a key factor in the control of scrapie according to Canadian regulations?
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What was the first recorded case of scrapie, and where did it occur?
What was the first recorded case of scrapie, and where did it occur?
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What type of fluids from infected ewes is known to present scrapie infectivity?
What type of fluids from infected ewes is known to present scrapie infectivity?
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Which treatment is associated with atypical scrapie, specifically Nor98?
Which treatment is associated with atypical scrapie, specifically Nor98?
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What was a notable challenge in scrapie eradication programs?
What was a notable challenge in scrapie eradication programs?
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What is a key characteristic that distinguishes infectious prions from normal prion proteins?
What is a key characteristic that distinguishes infectious prions from normal prion proteins?
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Which of the following best describes the implications of bovine spongiform encephalopathy (BSE) on agriculture?
Which of the following best describes the implications of bovine spongiform encephalopathy (BSE) on agriculture?
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Which method is most effective for inactivating prions in a laboratory setting?
Which method is most effective for inactivating prions in a laboratory setting?
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How does scrapie primarily spread among sheep populations?
How does scrapie primarily spread among sheep populations?
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What is a notable challenge in detecting prion diseases such as Creutzfeldt-Jakob Disease?
What is a notable challenge in detecting prion diseases such as Creutzfeldt-Jakob Disease?
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What evidence supports the ongoing environmental persistence of prions?
What evidence supports the ongoing environmental persistence of prions?
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For the control measures of scrapie, what is a critical aspect that must be adopted?
For the control measures of scrapie, what is a critical aspect that must be adopted?
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In Western blot analysis of prions, what is the relevance of using proteinase K?
In Western blot analysis of prions, what is the relevance of using proteinase K?
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What is the main purpose of the Ruminant Feed Ban implemented in Canada in 2007?
What is the main purpose of the Ruminant Feed Ban implemented in Canada in 2007?
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Which characteristic distinguishes Atypical BSE from Classical BSE?
Which characteristic distinguishes Atypical BSE from Classical BSE?
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What is a primary feature of Chronic Wasting Disease (CWD)?
What is a primary feature of Chronic Wasting Disease (CWD)?
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What are Specified Risk Materials (SRM) as per the 2007 feed ban regulations?
What are Specified Risk Materials (SRM) as per the 2007 feed ban regulations?
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Why is the detection of Chronic Wasting Disease (CWD) complicated?
Why is the detection of Chronic Wasting Disease (CWD) complicated?
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What is one major risk associated with feeding infected meat and bone meal to cattle?
What is one major risk associated with feeding infected meat and bone meal to cattle?
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Which prion disease is recognized for its zoonotic potential?
Which prion disease is recognized for its zoonotic potential?
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What is a significant consequence of the environmental persistence of prions in relation to agriculture?
What is a significant consequence of the environmental persistence of prions in relation to agriculture?
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Which species has exhibited a higher prevalence of Chronic Wasting Disease than white-tailed deer in Saskatchewan?
Which species has exhibited a higher prevalence of Chronic Wasting Disease than white-tailed deer in Saskatchewan?
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What is considered a likely transmission route of Chronic Wasting Disease in moose?
What is considered a likely transmission route of Chronic Wasting Disease in moose?
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What is the current status of treatment options for Chronic Wasting Disease?
What is the current status of treatment options for Chronic Wasting Disease?
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Among the following species, which is considered very susceptible to Chronic Wasting Disease?
Among the following species, which is considered very susceptible to Chronic Wasting Disease?
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What percentage of male mule deer tested positive for Chronic Wasting Disease during the 2022/2023 monitoring in Saskatchewan?
What percentage of male mule deer tested positive for Chronic Wasting Disease during the 2022/2023 monitoring in Saskatchewan?
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What best describes the primary component of infectious prions?
What best describes the primary component of infectious prions?
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Which of the following methods effectively inactivates prions?
Which of the following methods effectively inactivates prions?
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What is the purpose of using proteinase K in distinguishing between normal and abnormal prions?
What is the purpose of using proteinase K in distinguishing between normal and abnormal prions?
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What is the estimated duration of the clinical phase for human prion diseases like Creutzfeldt-Jakob Disease?
What is the estimated duration of the clinical phase for human prion diseases like Creutzfeldt-Jakob Disease?
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Which of the following statements accurately describes prion disease detection methods?
Which of the following statements accurately describes prion disease detection methods?
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What distinguishes the protease resistance of abnormal prion proteins from that of normal prion proteins?
What distinguishes the protease resistance of abnormal prion proteins from that of normal prion proteins?
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Which statement best describes the antibody response to prion infections?
Which statement best describes the antibody response to prion infections?
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What type of diseases are characterized by abnormal prion protein accumulation?
What type of diseases are characterized by abnormal prion protein accumulation?
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What is the primary source of infectious prions in infected animals?
What is the primary source of infectious prions in infected animals?
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How does the incubation period of prion diseases in humans generally compare to that of infected cattle?
How does the incubation period of prion diseases in humans generally compare to that of infected cattle?
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Which of the following statements correctly describes the characteristics of the infectious form of prion protein?
Which of the following statements correctly describes the characteristics of the infectious form of prion protein?
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What role does the Prion Protein (PrP) play in the host organism?
What role does the Prion Protein (PrP) play in the host organism?
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Which prion disease is characterized by a long incubation period and affects various animal species?
Which prion disease is characterized by a long incubation period and affects various animal species?
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Which statement regarding the infectivity of prions in animal brains is true?
Which statement regarding the infectivity of prions in animal brains is true?
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What are the characteristics of prion diseases in terms of treatability and resistance to inactivation?
What are the characteristics of prion diseases in terms of treatability and resistance to inactivation?
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Which prion disease affects humans and is associated with consumption of infected beef?
Which prion disease affects humans and is associated with consumption of infected beef?
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What are the characteristics of the PRNP gene related to scrapie resistance and susceptibility?
What are the characteristics of the PRNP gene related to scrapie resistance and susceptibility?
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Which of the following statements best describes the transmission of scrapie among sheep?
Which of the following statements best describes the transmission of scrapie among sheep?
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What is the primary challenge faced in the eradication of scrapie over the decades?
What is the primary challenge faced in the eradication of scrapie over the decades?
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Which treatment is associated with the study of atypical scrapie and involves proteinase K?
Which treatment is associated with the study of atypical scrapie and involves proteinase K?
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What is the estimated economic impact of Bovine Spongiform Encephalopathy (BSE) on the Canadian cattle industry?
What is the estimated economic impact of Bovine Spongiform Encephalopathy (BSE) on the Canadian cattle industry?
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What is a unique feature of Atypical Scrapie compared to Classical Scrapie?
What is a unique feature of Atypical Scrapie compared to Classical Scrapie?
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Which aspect is crucial for producers to minimize the risk of scrapie in their sheep flocks?
Which aspect is crucial for producers to minimize the risk of scrapie in their sheep flocks?
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What is a significant characteristic of the environmental contamination associated with scrapie?
What is a significant characteristic of the environmental contamination associated with scrapie?
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Which age group of cattle is primarily affected by Atypical BSE?
Which age group of cattle is primarily affected by Atypical BSE?
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What is a critical environmental characteristic of Chronic Wasting Disease (CWD)?
What is a critical environmental characteristic of Chronic Wasting Disease (CWD)?
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What distinguishes Atypical BSE from Classical BSE?
What distinguishes Atypical BSE from Classical BSE?
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Which of the following statements about the Ruminant Feed Ban is accurate?
Which of the following statements about the Ruminant Feed Ban is accurate?
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What is the major zoonotic risk associated with Bovine Spongiform Encephalopathy (BSE)?
What is the major zoonotic risk associated with Bovine Spongiform Encephalopathy (BSE)?
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Which category of materials is designated as Specified Risk Materials (SRM)?
Which category of materials is designated as Specified Risk Materials (SRM)?
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What is a notable feature of Chronic Wasting Disease regarding testing methods?
What is a notable feature of Chronic Wasting Disease regarding testing methods?
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What is the primary cause of Classical BSE in cattle?
What is the primary cause of Classical BSE in cattle?
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Study Notes
Scrapie
- A disease of sheep and goats
- First recorded case in the UK: 1732
- First case in Canada: 1938
- First case in the U.S.: 1947
- Worldwide distribution
- Scrapie eradication has been challenging over decades, but current approaches are successful
Scrapie Transmission
- Contagious
- Scrapie infectivity is present in fluid and tissue from the placentas of infected ewes
- Environmentally persistent: >15 years
PRNP Gene
-
+H -COO- 3N-
136 154 171
ARR resistance to scrapie
VRQ susceptible to scrapie
VRQ/VRQ highly susceptible ARR/ARR highly resistant
Controlling Scrapie: Canadian Food Inspection Agency (CFIA) Program
- Scrapie is a Reportable Disease
- Suspect cases must be reported to a CFIA veterinarian immediately
- Sheep documented with scrapie and all animals exposed to the same birthing environment must be destroyed
- Producers are compensated for the loss of their animals
- Producers can consider selective breeding for genetic resistance to scrapie to minimize the risk of scrapie in their sheep flock
Atypical vs Classical Scrapie
- Atypical Scrapie
- Nor98
- PK treatment: low molecular weight (10-12 kDa)
- Increased PK sensitivity
- More abundant in the cerebellum and cortex than the brainstem
- Identified in "scrapie-resistant" sheep, A136 R154 R171
- Abundance?
- Classical Scrapie
- Bovine Spongiform Encephalopathy
- Friesian cow, 9 years old
- ~200,000 cattle (Great Britain)
- 26 Cattle (North America)
The Cost of BSE
- The cost of BSE to the Canadian cattle industry has been estimated to be around $7 billion dollars.
Prion Infectivity and Food Chain
- Prions are resistant to inactivation
- Prion infectivity remains in meat and bone meal
- Infected meat and bone meal was added to cattle feed
Ruminant Feed Ban
- Prohibits the feeding of:
- Most mammalian-derived proteins to ruminants
- Poultry litter and restaurant waste to ruminants
- Canada: 1997.
- Feed ban 2007 (July 12, 2007)
- SRMs are also banned from all animal feeds, pet foods, and fertilizers.
- SRMs = "Specified Risk Materials": nervous tissue (skull, brain, spinal cord) from animals 30 months or older
BSE in North America
- 26 known BSE cases
- 1 imported from Great Britain (Red Deer, 1993)
- 5 US
- 20 or 21 Canada (Wash 2003)
- A = Atypical BSE
Classical vs Atypical BSE
- Classical BSE
- Caused by feeding cattle contaminated feed
- Average age of infected cattle: 4-5 years
Atypical BSE
- Very old cattle
- 10 years +
- Appears to be sporadic (randomly occurs)
- Distinguished from classical BSE by the characteristics of the abnormal prion protein
- NOT linked to animal feed (Meat and bone meal)!
Chronic Wasting Disease
- Contagious Prion disease
- Affects the central nervous system and lymphatic system.
- Always fatal
- No treatment or cure
- Complicated detection
- Post mortem --- No useful live tests
- CWD Strains
Chronic Wasting Disease Environmental Contamination
- Persists in the environment for years
- Long Preclinical Phase
- Slow Spread
- Confined to Cervids
- Zoonotic?
Zoonotic Potential
- Prion Disease Zoonotic?
- Scrapie No
- Bovine Spongiform Encephalopathy Yes
- Chronic Wasting Disease ?
PrPC
- Sequence as PrPC
- Metal homeostasis
- Resistant to degradation
- Necessary for prion infection
PrPC Prion Replication
- PrPSc - Converting PrPC to PrPSc
- PrPC - Normal Form of prion protein
- PrPSC - Abnormal form of prion protein
Detecting Prion Diseases: Factors
- Infectious agent
- Abnormal protein (PrPSC)
- No virus to culture or detect
- No bacteria to characterize
- Antibody Response
- None useful
- Serology not appropriate
- Extended Preclinical Stage, Short Clinical Stage
- Years
- Deer (chronic wasting disease)
- Cattle (bovine spongiform encephalopathy)
- Sheep (scrapie)
- Decades
- Humans (Creutzfeldt Jakob Disease)
- Years
Protease Resistance
- Means of distinguishing normal from abnormal prions
- Uninfected
- Normal form of prion protein (PrPC)
- PrPC + proteinase K = No protein
- Normal form of prion protein (PrPC)
- Infected
- Normal Form of prion protein + PrPCWD
- PrPCWD + PrPC + proteinase K = PrPCWD
- Normal Form of prion protein + PrPCWD
Protease Resistance: Uninfected vs Infected
- Uninfected Infected
- PrPC PrPC PrPSC
-
Proteinase K Proteinase K
-
PrPSC
Western Blot Analysis: Distinguishing PrPC from PrP CWD
- CWD+ CWD-
-
32 kDa
-
PK - + - + - + - +
-
50 ug/ml proteinase K (PK) 30 minutes
-
PrP Antibody: 6H4
Obex Staining (CWD)
- No detectable Obex score 1
-
Obex score 4
Infectious Prions Resist
- Chemical inactivation
- Acids
- Base
- Detergent
- Extreme conditions (1 N NaOH) will inactivate
- Standard Sterilization Methods
- Autoclaving---medical sterilization (120 o C 20 min)
- Extreme conditions (autoclaving at 134 C for 1 hour) will inactivate
- UV and gamma irradiation levels that inactivate most bacteria and viruses
Healthy or Infected?
- Protozoa, Helminths, Fungi Bacteria Viruses Prion Disease
-
Eukaryotic Prokaryotic DNA or RNA Protein + Protein coat
-
Nucleic Acid Detection Protein Detection
Prion Diseases
- Prion diseases are fatal neurodegenerative diseases caused by misfolded proteins called prions.
- These prions are highly resistant to inactivation and can persist in the environment for extended periods.
### Prion Diseases & Their Hosts
- Scrapie: Primarily affects sheep and goats.
- Bovine Spongiform Encephalopathy (BSE): Affects cattle.
- Chronic Wasting Disease (CWD): Impacts cervids, including deer, elk, and moose.
- Creutzfeldt-Jakob Disease (CJD): Occurs in humans.
- Variant CJD (vCJD): A human prion disease linked to BSE.
- Kuru: A human prion disease transmitted through ritualistic cannibalism.
Characteristics of Prion Diseases
- Spongiform Degeneration: The brain tissue develops holes, giving it a sponge-like appearance.
- Transmissible: Prion diseases are spread through the transfer of infectious prions.
- Long Incubation Period: It can take years to decades for symptoms to manifest after exposure.
- Extended Preclinical Stage: The disease can exist without visible symptoms for an extended period.
- Fatal: There is currently no cure for prion diseases.
- Extreme Resistance to Inactivation: Prions are highly resistant to conventional sterilization methods.
The Prion Protein (PrP)
- Normal Form (PrPC): Expressed on the cell surface of neurons, glia, and other peripheral cells.
- Infectious Form (PrPSc): Misfolded version of PrPC with a different conformation.
- PrPSc Conversion: PrPSc acts as a template to convert PrPC into the infectious form, leading to prion replication.
Detecting Prion Diseases
- Difficult to Detect: Currently, no reliable live tests exist.
- No Antibody Response: Serology is not effective for detecting prion infection.
- Protease Resistance: PrPSc resists proteinase K digestion, a characteristic used to distinguish it from PrPC.
Environmental Persistence
- Prions are highly resistant to inactivation and can persist in the environment for extended periods.
- This poses challenges for managing prion diseases, particularly regarding contaminated surgical instruments, animal products, and environmental contamination.
Scrapie
- History: First recorded in the UK in 1732, with global distribution.
- Transmission: Contagious through direct contact and environmental contamination.
- Eradication Efforts: Extensive but challenging due to prion resilience.
- Genetic Resistance: Sheep with certain PRNP gene variations (ARR) have increased resistance to scrapie.
- Atypical Scrapie: A strain distinct from classical scrapie, showing increased PK sensitivity and distribution in the brain.
Bovine Spongiform Encephalopathy (BSE)
- Origin: Linked to the feeding of meat and bone meal contaminated with prions.
- Impact: Caused significant economic losses and led to widespread bans on feeding mammalian-derived proteins to ruminants.
- North American Cases: Approximately 26 cases documented, with 1 imported from the UK and the rest attributed to sporadic events.
- Atypical BSE: Distinguished from classical BSE by age of infected cattle, characteristics of the abnormal prion protein, and is not believed to be linked to animal feed.
Chronic Wasting Disease (CWD)
- Impact: Affects cervids and is a significant concern for wildlife populations.
- Transmission: Contagious through direct contact, environmental contamination, and possibly through ingestion of contaminated feed.
- Zoonotic Potential: Research ongoing to determine if it poses a threat to humans.
- Current Status: Spreads throughout the US and Canada, with a substantial increase in prevalence.
- Control Challenges: No drugs, vaccines, or cures available; depopulation and population reduction efforts are ongoing.
CWD Susceptible Species
- White-tailed Deer: Highly susceptible and contribute to disease spread.
- Mule Deer: Highly susceptible with increased prevalence in Alberta and Saskatchewan.
- Elk: Susceptible with both free-ranging and captive populations affected.
- Moose: Susceptible but less common than other cervids, but environmental transmission is possible.
- Caribou: No cases reported in North America, but considered susceptible.
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Description
This quiz covers the disease scrapie, which affects sheep and goats. It includes information about its history, transmission methods, the PRNP gene's role in susceptibility, and how it is controlled under the Canadian Food Inspection Agency regulations. Test your knowledge on this contagious and challenging livestock disease.