Prions Flashcards
are prions dead or alive
good question
what is the chain of infection
infectious agent
reservoir
portal of exit
mode of transmission
portal of entry
susceptible host
what is an example of a prion disease
transmissible spongiform encephalopathies
describe transmissible spongiform encephalopathies
they can pass from one individual to another. spongiform is the appearance the infection causes in the brain, which appears spongy under the microscope.
what is transmissible spongiform encephalopathy
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
what is the name prion derived from
proteinaceous infection particle
what are the types of transmissible spongiform encephalopathies
classic CJD (sporadic)
kuru
scrapie
what does scrapie affect
sheep
what are the features of prions
- devoid of nucleic acid
- due to accumulation of an abnormal form of a natural protein
- as such, there is no immune response
are there prions in a healthy body
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
how are prion diseases unique
there are infectious agent forms like from contaminated blood, which could be genetic sporadic
how common are genetic sporadic prion diseases
one in a million across the globe
what causes the spongiform appearance of the brain
accumulation of a form of the prion protein that is difficult to degrade and accumulate over time to cause the spongiform appearance
why is there no immune response to prion diseases
they are a form of a normal protein
what are some prion inactivation agents
steam sterilisation of chemical disinfectant
how do prion proteins reproduce
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.
describe the biomechanics of prion protein production
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
what are the types of human CJD
sporadic
familial
iatrogenic
what is sCJD
sporadic CJD
what is fCJD
familial CJD
what is iCJD
iatrogenic CJD
how can iCJD be transmitted
by surgical instruments contaminated hormones and gradts.
what is kuru a form of
iatrogenic CJD
how is kuru iatrogenic CJD transmitted
generation to generation by cannibalistic rituals
how is variant CJD transmitted
consumption of contaminated food material from bovine spongiform encephalopathy
how many cattle had to be killed as a result of BSE
5 million
at what age does normal CJD occur
60 to 70
at what age does variant CJD occur
a much younger age in comparison to variant
how does the tissue infectivity of sporadic CJD compare to variant CJD
vCJD can spread outside of the central nervous system and affect the appendix, tonsils and spleen
what areas of the central nervous system are affected by CJD
- brain
- spinal cord
- cranial and spinal ganglia
- optic nerve
- retina
does CJD in any form have a large effect on blood or other tissues
no
how many years have passed since the arrival of a new clinical case of CJD
four years
which tissues in the oral cavity have been affected by forms of CJD
gingival
pulpal
saliva
tongue tissue
why is CJD clinically relevent in dentistry
can have an impact on the oral cavity as this is a fast way for the infection to reach the brain
which ganglion in the face can be affected by human CJD
the trigeminal ganglion that branches to supply the teeth and lip
why is abnormal prion protein such an issue in the dental setting
hard to clean from surgical instruments, can survive steam sterilisation. the incubation period can be decades long and carriage can be asymptomatic
which dental instruments can be connected with abnormal prion protein
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
are dental procedures high risk procedures for transmission of CJD
no, so the standard infection control precautions and cleaning can be used to treat people safely in our own dental practice
