18 - Prions

Question 1

Prion outbreak: disease was linked to using ______________ and rapidly became endemic in the UK and from there spread to other countries

Answer 1

slaughtered carcasses in animal feed

Question 2

It is estimated that ________ infected animals entered the food supply chain without being detected

Answer 2

3.5 million

Question 3

When the disease gets transmitted to humans it is known as ____________

Answer 3

variant Creutzfeldt-Jkob disease (vCJD)

Question 4

The practice of feeding agricultural waste to animals was banned in ____, cases after this were likely due to cross-feeding, and cross contamination.

Answer 4

1988

Question 5

Prionsareinfectious agents composed entirely of a___________ that can fold in multiple abstract ways and at least one of which is transmissible to other prion proteins. This leads to a disease that is epidemiologically comparable to the spread of ________

Answer 5

protein material

viral infection

Question 6

Prion composed of the prion protein (Prp) are believed to be the cause of _______________ among other diseases

Answer 6

transmissible spongiform encephalopathies (TSEs)

Question 7

Prions cause fatal ______________ in humans and animals by converting the cellular prion protein P____ into the aggregation-prone _____ .

Answer 7

neurodegenerative diseases
PrPC
PrPSc

Question 8

____________: biological material that has been obtained through sampling of infected individuals

Answer 8

isolate

Question 9

_________: the term corresponds to a defined prion population isolated from one specified animal

Answer 9

strain

Question 10

________: refers more particularly to a combination of biochemical parameters (mainly to the size of the unglycosylated PrPSc fragment after proteinase K partial digestion) that are independent from the host.

Answer 10

Type

Question 11

Each TSE disease shares some common characteristics:

Answer 11

• long incubation periods ranging from years to decades
• illness of weeks to months with invariable progression to death
• accumulation in the brain and other tissues of fibrillar amyloid protein aggregates (PrPTSE)
• Pathological changes confined to the CNS
• The absence of an immune response (cause it is only a misfolded protein - not recognized as foreign by the immune system)

Question 12

T or F: There are some biological differences in terms of pathogenesis, transmission, and distribution of infectivity in tissues

Answer 12

T

Question 13

Different strains of TSEs affect different humans and animals:

• scrapie affects ______ and _____
• chronic wasting disease affects ________
• transmissible mink encephalopathy affects ____
• kuru only affects ______, but really was only confined to Papua new Guinea cannibals

Answer 13

sheep and goats
cervids
mink
humans

Question 14

T or F: CWD first appeared in North America in captive animals in 1969 when biologists conducting a physiological study recognized that their animals often died with a syndrome of weight loss and behavioral changes

Answer 14

T

Question 15

CWD is a _______ developing disease, with prolonged _______________

Answer 15

slowly
incubation periods  (2-4 year incubation time)

Question 16

In most prion diseases, ______ and infectivity are restricted mainly to the brain. However, in _____, PrPSc can be found in many _______ tissues, body fluids, and excreta, facilitating ____________

Answer 16

PrPSc
CWD
extraneural
horizontal transmission.

Question 17

Name some natural CWD hosts:

Answer 17

• elk
• mule deer
• white-tailed deer
• moose
• reindeer

Question 18

_______ and _______ deer are also susceptible to CWD via experimental transmission

Answer 18

red deer and fallow deer

Question 19

T or F: A unique aspect of CWD is that unlike other prion diseases, indirect transmission also occurs via CWD prion deposition into the environment from urine, feces, and saliva onto and into water, soil, and plants.
Cervids and other animals likely consume prions contained in these reservoirs and become infected.

Answer 19

T (deers don’t have to ear each other to become infected)

Question 20

BSE =

Answer 20

Bovine spongiform encephalopathy

Question 21

Is it considered natural for a cow to eat the nervous system of another cow?

Answer 21

no

Question 22

It is suggested that sporadic disease of BSE may be cause by a __________ mutation

Answer 22

genetic

Question 23

Once cattle were infected, there is evidence to indicate that epidemic was perpetuated by _______________

Answer 23

feeding BSE-contaminated meat and bone meal to cattle

Question 24

In BSE, the stability of the protein shows an unusual resistance to destruction, protein can survive:

Answer 24

• heating under pressure at 121C
• exposure to dry heat at 600C
• immersion in 0.1N NaOH
• immersion in 0.5% bleach

Question 25

What do you need to do to inactivate the BSE protein:

Answer 25

1) Immersion in 1N NaOH
2) Dry heat at 1000C
* Can’t process to this extent and still have edible food
* when proteins enter the environment they may persist for years

Question 26

Animals affected by BSE develop _________________

Answer 26

degeneration of the nervous system (changes in temperament, abnormalities in posture and movement, signs of apprehension, nervousness, and aggression, incoordination, tremors, difficulty in standing)

Question 27

Animal is usually infected with BSE in ________________, though incubation is _________

Answer 27

first year of life

2-8 years

Question 28

When clinical symptoms develop, BSE may last from _____________

Answer 28

2 weeks to 6 months

Question 29

Humans likely became infected with vCJD by consumption of ______________

Answer 29

infected beef contaminated by CNS tissue

Question 30

Why were so few people infected given the magnitude of contamination (including only one family where more than one person was infected)?

Answer 30

The theory is that small packets of low-level infectivity were heterogeneously scattered through the meat

Question 31

In humans adolescents are afflicted, but only occasional cases in __________

Answer 31

adults over 50

Question 32

sporadic CJD usually occurs in humans ____

Answer 32

50-70
*clinical presentation is some psychiatric disturbance (depression or anxiety), complaints of sensory symptoms such as limb pain - average durations is 14 months

Question 33

How is BSE controlled now? (3)

Answer 33

1) Feed bans: regulations range from the banning of feeding ruminant remains back to ruminants, to prohibiting animal proteins to all animals for human consumption including fish
2) Specific risk materials (SRM) bans: Requires that high-infectivity materials such as bovine brain and spinal cord be removed from both the food and feed chains and be destroyed
3) Regulation of rendering: Materials used for slaughter require 20-minute autoclave exposure at 133C under 3 bars of pressure