Lecture 5: Significant Virus and Prion Diseases

Question 1

What is an obligate intracellular parasite?

Answer 1

• need host cell to survive
• need immunologically naive host or become extinct
• only virus that causes disease that does not kills host can survive in closed community
• ideal virus is one that can infect the host but not kill them.

Question 2

Check out the tables of all the significant viral disease on slides 4,5,6,7

Answer 2

yikes

Question 3

Is there a link between viruses and cancer? explain

Answer 3

Persistant viral infections can rarely lead to neoplasm formation
-continuous infections like Hep B and C can lead to cancer (hematomacrosis)

Question 4

Prions- what is it?

Answer 4

A prion is a small infectious particle composed of abnormally folded protein that causes progressive neurodegenerative conditions. These mis-folded proteins do not multiply in the host organism that they infect. Instead they affect the brain structure by acting as a template, inducing proteins with normal folding to convert to the abnormal prion form.
These newly formed mis-folded proteins, in turn, act as further templates for the conversion of more normal proteins. There is therefore an exponential accumulation of the prions in the tissue of the central nervous system.

Question 5

Prions are resistant to all sorts of things including?

So what does work against prions?

Answer 5

• chemical disinfectants
• heat
• DNAase, RNAase, proteinases (enzymes that break down DNA and RNA)
• UV light, oozing radiation
• heat (cooking temp)
• high temp autoclaving
• burying for 3 years
• formaldehyde fixation
• survive in pastures
• steralize all heat resistant surgical instruments to ensure they aren’t contaminated with prions
• immerse in 1M NaOh and heat in a gravity- displacement autoclve at 121C for 30 mins; cleanm rinse in water then perform routine sterilisation tests

Question 6

Check out the table on slide 14 for Prion diseases, their hosts and how they are acquired.

Answer 6

nchey

Question 7

How do prions form?

Answer 7

• when an abnormal proton protein comes into contact with a normal protein it flips the normal protein into the abnormal shape
• some are though to just spontaneously occur.