Prion

Question 1

What is a Prion?

Answer 1

Prion: infectious agents composed entirely of a protein material that can fold in multiple abstract ways and at least one of which si transmissible to other prion proteins. This lead to disease epidemiologically comparable to spread of virus. Composed of Prion Protein (PrP) and are believed to cause transmissible spongiform encephalopathies (TSEs) among other diseases
Cause fatal neurodegenerative diseases in humans and animals by converting the cellular prion protein (PrPC) into the aggregation-pron PrSc

Question 2

What is the difference between a isolate, strain and type?

Answer 2

Isolate: biological material obtained through sampling
Strain: defined prion population isolated from specific animal
Type: refers to biochemical parameters (unglycosylated prPSc fragment after proteinase K partial digestion) that is independent from the host

Question 3

What are the characteristics of Trasnmissilb eSpongiform Encephalopathies?

Answer 3

Long incubation periods
Illness is invariable
Accumulation in the brain and other tissues of friburlar amyloid proteins aggregates (PrP)
Pathological changes to CNS
Absence of immune response

Question 4

What makes TSEs different?

Answer 4

Pathogenesis

Transmission and distribution of infectivity

Question 5

What is chronic wasting disease and how do you control it?

Answer 5

Syndrome of weight loss and behavioral changes, after incubation of 2-4 years
Infectivity restricted to the brain but prPSc can be found in extraneural tissues: body fluids, excrete → facilitates horizontal transfer and can persist in the environment
Affects elk, deer, moose, reindeer
For captive animals, quarantine and depopulations of CWD herds, hard to reduce in free-ranging animals

Question 6

How do you get rid of Bovine Spongiform Encephalopathy?

Answer 6

VERY stable protiensStability of the protein:
High pressure of 121C
Exposure to 600C dry heat
Immersionin 01M NaOh
Immersion of 0.5% bealch
To inactivate the protein
Immersin of 1M NaOH
Dry heat of 10000C
Persis for years (2-8 year incubation) in the environemnt- can’t process and still have food, need to get rid of it all

Question 7

How do you control BSE?

Answer 7

1- Fee barns: regulate range form the banning of feeding remains back to ruminants, to prohibiting animal proteins to all animals for human consumption included fish
2- Specified Risk MAterials (SRM) bans: requires that high infectivity materials such as bovine brains and spinal cord be removed from both the food and feed chains and be destroyed
3- REgulations of Rendering: Materials used for slaughter require 20 minutes autoclave exposure at 133C under 3 bars pressure - GAP

Question 8

Describe the infectivity of CJD( Creutzfeldt-Jakob disease).

Answer 8

First recognized in the UK 10 years after BSE (incubation of 12-15 years)
Humans likely became infected given the magnitude of contamination
Theory: small packets of low level infectivity are heterogenous in meat, means one person from the family can show symptoms, other none
Adolescents affected, adutls over 50, sporadic
Clinical presentation: psychiatric disturbance (dpression, anxiety), complaints of sensory symptoms (limb pain)- 14 months