(6-15) Cannibals & Cows [Prions]

Question 1

What are the symptoms of Kuru?

Answer 1

1. Unsteady gait
2. Slurring of speech
3. Muscle jerking
4. Incontinence
5. Lack of immune response

Question 2

What is the cause of symptoms in kuru?

Answer 2

Brain dysfunction

Question 3

What is kuru and when did it first arise?

Answer 3

In the early 1900s, a fatal neurodegenerative disease arose in Papua New Guinea

Question 4

How many of South Fore people (women and children) Died of kuru from 1957 - 1968?

Answer 4

Over 1100

Question 5

What happened when chimpanzees were injected with brain tissue from Kuru victims?

Answer 5

18 to 21 months later, they developed symptoms similar to Kuru.

Question 6

How was kuru transmitted from person-to-person in the south fore?

Answer 6

People in the South Fore partake in ritual acts of mortuary cannibalism. The women and children who lived apart from the men cooked and ate their dead relatives.

Question 7

What did scientists believe that Kuru was?

Answer 7

A slow virus

Question 8

What is Scrapie?

Answer 8

Neurodegenerative sheep disease first described in early 18th century

Question 9

What are the symptoms of Scrapie?

Answer 9

Sheep trembled, stumbled, and scraped against fences

Question 10

How do the brains of Scrapie sheep appear?

Answer 10

Brains were spongiform, hence the disease name, Scrapie spongiform encephelopathy.

Question 11

How is Scrapie transmitted?

Answer 11

Scrapie is known to be transmissible from one sheep to another via brain tissue

Question 12

What is a prion?

Answer 12

Proteinaceous Infectious particles, which contain protein, but nut nucleic acid.

Question 13

How did prions arise?

Answer 13

Prions apparently arose from mutations in the gene encoding normal prion proteins in humans and animals.

Question 14

What is fractionation?

Answer 14

A process that uses heat to separate a substance into its components.

Question 15

Can prions “reproduce” without nucleic acids?

Answer 15

1. Yes– sort-of.
2. Abnormal protein can cause normal cellular protein to change to abnormal form
3. PP + NP → PP + PP

Question 16

How can PP change NP into PP?

Answer 16

PP interacts with NP in such a way as to facilitate the re-folding to the PP confirmation.

Question 17

How do point-mutations in the NP affect its resistance to prions?

Answer 17

Some point-mutations in the NP make it more prone to abnormal re-folding

Question 18

How do normal protein conformations differ from abnormal ones?

Answer 18

1. Normal protease-sensitive conformation has normal cellular function in cells
2. Abnormal protease-resistant conformation accumulates and cause neuron death

Question 19

How structurally similar are PPs and NPs?

Answer 19

~ PPs were found to be almost identical to a normal human cellular protein (NP)
~Normal protein not protease resistant
~ Sequences are almost identical
~ Explains lack of immune response

Question 20

What did Stanley Prusiner win the 1997 Nobel Prize in Physiology or Medicine for?

Answer 20

He suggested infectious disease could be transmitted by protein alone.

Question 21

Why do prions appear to have a long “incubation time”?

Answer 21

Re-folding NP to the PP confirmation continues (slowly) inside neurons until pathology occurs

Question 22

What is Genetic Creutzfeldt-Jacob Disease (CJD)?

Answer 22

Inheritance of a form of NP that folds into the abnormal form very easily

Question 23

What is Sporadic CJD, whom does it affect, and how frequently does it occur?

Answer 23

Sometimes your NP spontaneously fold into the abnormal form
~ Rare (1 case in 1,000,000)
~ Primarily in age >45

Question 24

What is Variant CJD and whom does it affect?

Answer 24

PP from ‘Mad Cows’ leads to disease by re-folding NP

~ Younger people infected

Question 25

Do cured “mad cows” mean no more Mad Cow Disease in humans?

Answer 25

No. The occurrence of BSE in humans lags behind that in cows.

Question 26

Which prion disease affects sheep?

Answer 26

Scrapie spongiform encephalophathy

Question 27

Which prion disease affects cows and humans?

Answer 27

Mad cow spongiform encephalophathy

Question 28

Which 2 prion diseases affect humans?

Answer 28

1. Creutzfeldt-Jacob Disease

2. Kuru spongiform encephalophathy

Question 29

Which prion disease affects Deer and Elk?

Answer 29

Chronic wasting disease

Question 30

How did the spread of kuru stop?

Answer 30

The South Fore stopped eating their dead.

Question 31

Are there still Kuru cases today? Who is affected?

Answer 31

The long incubation time means that even today there are a few kuru cases every year, in 50 to 60 year olds who ate infected tissue as young children.