Prions

Creutzfeldt-Jacob disease

CJD

Human prion diseases

CJD, iCJD, vCJD, fCJD, sCJD, GSS, sFI, Kuru

CWD (chronic wasting disease)

affected animals: white-tailed deer, elk, mule deer, moose

Characteristics of variant CJD

Median age at death: 28 yrs Median duration of illness: 13-14 months clinical signs and symptoms: prominent psychiatric/behavioral symptoms; painful dysesthesias; delayed neurologic signs periodic sharp waves on EEG: often absent

Characteristics of classic CJD

Median age at death: 65 yrs Median duration of illness: 4-5 months clinical signs and symptoms: dementia; early neurologic signs periodic sharp waves on EEG: often present

FSE (feline spongiform encephalopathy)

affected animals: cat

BSE

affected animals: cattle

TME (transmissible mink encephalopathy)

affected animals: mink

Scrapie

affected animals: sheep and goat

prions cause neurodegenerative disease by

aggregating extracellularly within the central nervous system to form plaques known as amyloid, which disrupt the normal tissue structure. This disruption is characterized by 'holes' in the tissue with resultant spongy architecture due to the vacuole formation in the neurons

transmissible spongiform encephalopathies (TSEs)

all known prion diseases are collectively called ______, and are untreatable and fatal.

Many different mamalian species can be affected by prion diseases

as the prion protein (PrP) is very similar in all mammals

kuru incubation period

asymptomatic for 5-20 years following initial exposure

the mis-folded form of the prion has

been implicated in a number of diseases in a variety of mammals including BSE (mad cow disease) and CJD in humans.

prion propagation/reproduction

by transmitting a mis-folded protein state; as with viruses the protein itself does not self-replicate, rather it induces existing polypeptides in the host organism to take on the rogue form

transmission of kuru

cannibalistic funeral practices in which the men of the village took the choice cuts, the women and children would eat the rest including the brain, where prion particles were particularly concentrated. (8-9x more prevalent in women and children)

Stanley Prusiner

coined the word prion as a name for the infectious agent, was awarded the nobel prize in 1997 for his research into prions

How can you get CJD?

genetically through a mutation of the gene that codes for the prion protein (PRNP), this only occurs in 5-10% of all CJD cases. Latrogenic transmission, many cases in which transmission is unknown.

the human prion disease Variant CJD (vCJD)

however is believed to be caused by a prion which typically infects cattle causing BSE and is transmitted through infected meat

to sterilize prions

immerse in a pan containing 1N NaOH and heat in a gravity-displacement autoclave at 121C for 30min; clean; rinse in water; and then perform routine sterilization processes

trembling is present

in almost all patients with TSEs

portmanteau

is a combination of two (or more) words or morphemes into one new word

CJD

is a degenerative neurological disorder (brain disease) that is incurable and invariably fatal. It is the most common among the among the types of TSEs in humans

prion

is an infectious agent that is composed primarily of protein

vCJD

is believed to be caused by a prion which typically infects cattle, causing BSE and is transmitted through infected meat

Kuru

is believed to be caused by prions and is related to CJD. It is best known for the epidemic that occured in papa new guinea. although considered a transmissible prion disease, thought to be caused by cannibalism of a individual with CJD

Although CJD is the most common human prion disease

it is still rare, occuring in about 1 in 1million people every year. Usually affects people 45-75, most commonly 60-65. The exception to this is vCJD which occurs in younger poeple

transmission of CWD is thought to be

lateral (from animal to animal), maternal transmission may occur, an infected deer's saliva is able to spread the CWD prions

Bovine spongiform encephalopathy (BSE)

mad cow disease

while the incubation period for prion diseases is long

once symptoms appear the disease progresses rapidly, leading to brain damage and death. Neurodegenerative symptoms can include convulsions, dementia, ataxia (balance and coordination dysfunction), and behavioral or personality changes

chronic wasting disease

origin and mode of transmission of the prions causing CWD is unknown, but recent research indicates that prions can be excreted by deer and elk, and is transmitted by eating grass growing in contaminated soli

prions are generally quite resistant to

proteases, heat, radiation and formalin treatments

Latrogenic transmission

the medical staff caused the infection

Obex

the portion of the brain that must be obtained for the diagnosis of TSEs, scrapie and chronic wasting disease

all known prion diseases affect

the structure of the brain and other neural tissue and all are currently untreatable and are always fatal

the word prion is derived from

the words proteinaceous and infection

prions are infectious by

their effect on normal versions of protein. Sterilizing prions therefore involves the denaturation of the protein to a state where the molecule is no longer able to induce the abnormal folding of normal proteins.

Prion Protein (PrP)

while the infectious agent was named a prion, the specific protein that the prion was composed of is also known as ________ and may occur in both infectious and non infectious forms

In Rance and England

whole herds of cattle have been put to death in an effort to prevent the spread of disease