Lec 7 - Viruses and CNS

Question 1

for which viruses is neural spread a definitive characteristic of pathogenesis

Answer 1

rabies
alphaherpes

Question 2

in which viruses is CNS spread ‘accidental’

Answer 2

polio
only 1% of cases
mostly spread by haematogenous route

Question 3

where must viruses go in neurone for it to replciate

Answer 3

to cell body via microtubules and motor proteins

Question 4

Neurotropic

Answer 4

virus can infect neural cells via neural or haematogenous route.

Question 5

Neuroinvasive

Answer 5

virus can enter the central nervous system after infection of a peripheral site

Question 6

Neurovirulent

Answer 6

virus can cause disease of nervous tissue cause neurological symptoms and often death.

Question 7

2 types of movement a virus can have in neuron

Answer 7

retrograde
anterograde

Question 8

what motor protein is used for retrograde and anterograde movement

Answer 8

r= dyenin
a = kinesin

Question 9

3 main serotypes of polio virus

Answer 9

• brunhilde
• lansing
• leon

Question 10

proportion of symptoms people get with polio

Answer 10

90% subclinical
5-10% = nonparalytic
1% = paralytic

Question 11

what is incubation period for polio and why so variable

Answer 11

3-35 days
depends on number of virions you’re exposed to, how long it takes for them to replicate and cause damage

Question 12

why the paralysis with polio

Answer 12

viral replication in motor neurons
cell lysis = destroys motor neurons
depending on how much destruction, might or might not be able to recover

Question 13

where are the motor neurones that polio affects

Answer 13

anterior horn and brain stem

Question 14

how does polio enter body

Answer 14

via faecal oral route

Question 15

first place polio replicates

Answer 15

oralpharync
and in intestinal muscosal surfaces

Question 16

in those with polio paralysis, where does virus go after primary viremia

Answer 16

• reticuloendothelial cells
• spleen
• liver
• muscle
• brown fat tissue

Question 17

polio receptor

Answer 17

CD155
can only infect cells that express this

Question 18

replacing polio IRES with rhinovirus IRES allows what>

Answer 18

• minimal replication in neural tissue
• can inject into glioblastoma
• trigger immune repsonse

Question 19

rabies virus type

Answer 19

ssRNA
membrane bound

Question 20

2 glycoproteins that rabies has

Answer 20

• adhesin
• matrix protein

Question 21

2 types of rabeis transmission

Answer 21

• mostly animal to human
• very rarely iatrogenic (cornea translpant)

Question 22

why does incubation vary sm in rabies

Answer 22

depends of severity of wound
location of wound
inoculum size

Question 23

how does rabies travel in neurones

Answer 23

retrograde

Question 24

after rabies in CNS, how does it spread

Answer 24

in anterograde manner via efferent and afferent neural pathways

Question 25

what is prodome period

Answer 25

period of subclinical signs and symptoms that precedes the onset of psychosis

Question 26

symptoms of rabies

Answer 26

furious form = fever, anorexia, nausea
then
acute encephalitic phase = hydrophobia, hallucinations, excitement, shedding of virus in slaiva

OR

numb (paralytic form) = 20% of infecctions
= flaccid paralysis

Question 27

where does rabies adhesin glycoprotein target on muscle cells

Answer 27

nAChR on post synaptic muscle membrane

Question 28

how does rabies move from muslce to neurone

Answer 28

via neural cell adhesion molecule (NCAM)

Question 29

virulence stragetegies of rabies virus

Answer 29

-prevent cell death:
- immune unresponsiveness
- limit T cell proliferation
- keep blood brain barrier closed
- abolish apoptotic capability of the cell