Prions

Question 1

are prions dead or alive

Answer 1

good question

Question 2

what is the chain of infection

Answer 2

infectious agent
reservoir
portal of exit
mode of transmission
portal of entry
susceptible host

Question 3

what is an example of a prion disease

Answer 3

transmissible spongiform encephalopathies

Question 4

describe transmissible spongiform encephalopathies

Answer 4

they can pass from one individual to another. spongiform is the appearance the infection causes in the brain, which appears spongy under the microscope.

Question 5

what is transmissible spongiform encephalopathy

Answer 5

a fatal neurological disease with no known cure that occurs due to the accumulation within the central nervous system of insoluble aggregates of a cell membrane protein called prion protein

Question 6

what is the name prion derived from

Answer 6

proteinaceous infection particle

Question 7

what are the types of transmissible spongiform encephalopathies

Answer 7

classic CJD (sporadic)
kuru
scrapie

Question 8

what does scrapie affect

Answer 8

sheep

Question 9

what are the features of prions

Answer 9

• devoid of nucleic acid
• due to accumulation of an abnormal form of a natural protein
• as such, there is no immune response

Question 10

are there prions in a healthy body

Answer 10

yes, we have normal prion proteins that reside on the exterior surface of the cell membrane that have a believed role in relation to intercellular communication

Question 11

how are prion diseases unique

Answer 11

there are infectious agent forms like from contaminated blood, which could be genetic sporadic

Question 12

how common are genetic sporadic prion diseases

Answer 12

one in a million across the globe

Question 13

what causes the spongiform appearance of the brain

Answer 13

accumulation of a form of the prion protein that is difficult to degrade and accumulate over time to cause the spongiform appearance

Question 14

why is there no immune response to prion diseases

Answer 14

they are a form of a normal protein

Question 15

what are some prion inactivation agents

Answer 15

steam sterilisation of chemical disinfectant

Question 16

how do prion proteins reproduce

Answer 16

prion protein is proposed to be produced from the prion protien gene and is translated to prion protein cellular, which could encounter an abnormal form of prion protein, which can alter the shape of the normal cell protein to convert it to another abnormal prion protein.

Question 17

describe the biomechanics of prion protein production

Answer 17

the inital change from one abnormal prion protein to many is slow, but once you have achieved the transformation there is more rapid aggregation of the prion proteins to give a more spongiform appearance in the human brain tissue

Question 18

what are the types of human CJD

Answer 18

sporadic
familial
iatrogenic

Question 19

what is sCJD

Answer 19

sporadic CJD

Question 20

what is fCJD

Answer 20

familial CJD

Question 21

what is iCJD

Answer 21

iatrogenic CJD

Question 22

how can iCJD be transmitted

Answer 22

by surgical instruments contaminated hormones and gradts.

Question 23

what is kuru a form of

Answer 23

iatrogenic CJD

Question 24

how is kuru iatrogenic CJD transmitted

Answer 24

generation to generation by cannibalistic rituals

Question 25

how is variant CJD transmitted

Answer 25

consumption of contaminated food material from bovine spongiform encephalopathy

Question 26

how many cattle had to be killed as a result of BSE

Answer 26

5 million

Question 27

at what age does normal CJD occur

Answer 27

60 to 70

Question 28

at what age does variant CJD occur

Answer 28

a much younger age in comparison to variant

Question 29

how does the tissue infectivity of sporadic CJD compare to variant CJD

Answer 29

vCJD can spread outside of the central nervous system and affect the appendix, tonsils and spleen

Question 30

what areas of the central nervous system are affected by CJD

Answer 30

- brain - spinal cord - cranial and spinal ganglia - optic nerve - retina

Question 31

does CJD in any form have a large effect on blood or other tissues

Answer 31

no

Question 32

how many years have passed since the arrival of a new clinical case of CJD

Answer 32

four years

Question 33

which tissues in the oral cavity have been affected by forms of CJD

Answer 33

gingival pulpal saliva tongue tissue

Question 34

why is CJD clinically relevent in dentistry

Answer 34

can have an impact on the oral cavity as this is a fast way for the infection to reach the brain

Question 35

which ganglion in the face can be affected by human CJD

Answer 35

the trigeminal ganglion that branches to supply the teeth and lip

Question 36

why is abnormal prion protein such an issue in the dental setting

Answer 36

hard to clean from surgical instruments, can survive steam sterilisation. the incubation period can be decades long and carriage can be asymptomatic

Question 37

which dental instruments can be connected with abnormal prion protein

Answer 37

dental instruments like matrix bands and endodontic files had residual blood and tissue after cleaning and sterilisation, which could be a risk of transmission despite being sterilised

Question 38

are dental procedures high risk procedures for transmission of CJD

Answer 38

no, so the standard infection control precautions and cleaning can be used to treat people safely in our own dental practice