TSE/BSE

Question 1

Give examples of TSEs of animals

Answer 1

• Scrapie (Sheep and goats)
• Chronic wasting disease (Deer and elk)
• Bovine Spongiform Encephalopathy (Cattle, Cats, Goats and exotic ungulates )

Question 2

What are TSEs

Definition

Answer 2

Transmissible Spongiform Encephalopathy

Question 3

What are TSEs

Answer 3

• Neurological disorders
• Neuronal loss
• Invariably Fatal
• Very long incubation periods

Question 4

What causes TSEs

Answer 4

Misfolded prion protein (PrPsc)

Question 5

When was BSE first identified in UK cattle

Answer 5

1986

Question 6

Describe the control measures put in place because of the BSE out break

Answer 6

• Culling, cohort culling (cows on the farm born 2 years before and after the birth of the infected cow)
• Feed ban for ruminant material
• older cattle banned from food chain
• ban on specified-risk material from food chain( CNS)
• export ban
• surveillance

Question 7

Clinical signs of TSEs

Answer 7

• weight loss
• behaviour changes (hypersensitive)
• licking lips, grinding teeth, scratching
• pruritus (itching just scrapie)
• posture, gait
• Ataxia, tremors
• None, sometimes animal just found dead

Question 8

Why are TSEs hard to diagnose with clinical signs

Answer 8

The clinical signs don’t specifically show that it is a TSE could be different disease causing these issues

Question 9

Describe the properties of prions

Answer 9

• convert normal PrPc to PrPsc
• relatively insoluble
• exceptionally high stability for protein

Question 10

What are prions resistant to

Answer 10

• proteases
• heat treatment
• UV

Question 11

Describe the issues cause by prions high stability

Answer 11

• can’t easily decontaminate premises or in a clinical setting
• can survive in environmental reservoirs for many years

Question 12

Where is the primary site for pathogenic prions in the brain

Answer 12

• The obex (caudal part of the medulla)

Question 13

Describe the composition of PrPc

Answer 13

(Normal)

Rich in alpha helices

Question 14

Describe the composition of PrPsc

Answer 14

Rich in beta pleated sheets
Have some alpha helices
Misfolded protein

Question 15

How does infection by PrPsc occur

Answer 15

• ingestion of PrPsc contaminated feeds
• Horizontal transmission during perinatal period
• Superfical abrasion s
• Environmental

Question 16

How is a TSE diagnosed

Answer 16

A diagnosis of TSE can only be made b demonstrating the presence of prion protein (has to be done post mortum )

Question 17

Describe the TSE confirmatory test most used

Answer 17

Immunoassays- western blots and ELISAs (rely on the protease resistance of PrPsc compared to PrPc)
Positive test= 3 bands produced

Question 18

Are TSEs Zoonotic

Answer 18

BSE= Zoonotic 
CWD= unlikely to be zoonotic 
Scrapie = non-zoonotic

Question 19

Explain the economic impact of TSEs in the uk

Answer 19

• loss of income for agriculture/ government compensation
• export ban
• collapse of home market for beef
• lower market for milk/ lamb
• cost of surveillance
• cost of research