Lecture 21 - Poliovirus

Question 1

What genome type do Polioviruses have?

Answer 1

(+) ssRNA

Question 2

What effect does Polio generally cause people?

Answer 2

paralysis

Question 3

Has Polio been eradicated?

Answer 3

no

Question 4

What disease does Poliovirus cause?

Answer 4

Poliomyelitis

Question 5

What type of virus is Poliovirus? What does that mean?

Answer 5

enterovirus = intestines = where the virus likes to infect

Question 6

What can be done with a (+)ssRNA? What is it’s template? How can it be translated into protein?

Answer 6

(+)ssRNA –> (-)ssRNA = template to make more (+)ssRNA | can be directly translated into protein

Question 7

Where do enteroviruses multiply?

Answer 7

mucosa of the gut

Question 8

How serious are most of the diseases due to enteroviruses?

Answer 8

usually mild and result in full recovery of the patients

Question 9

What viral family are Polioviruses part of?

Answer 9

Picornaviridae

Question 10

What does it tell us about Polioviruses due to the fact that they are very resistant to most of the antimicrobials used to target viruses?

Answer 10

can stick around for a long time and hard to eliminate it

Question 11

Where is VP4 found?

Answer 11

inside of capsid

Question 12

Where is the VPg protein found? At end of the genome?

Answer 12

found on the RNA (+ss) genome | 5’ end

Question 13

What is VPg used for?

Answer 13

replication, serves as a protein primer

Question 14

What significant structure is at the 5’ end? What purpose does it serve?

Answer 14

clover-leaf tRNA-like structure = serves as an internal ribosomal entry site (IRES)

Question 15

What does the internal ribosomal entry site (IRES) mean?

Answer 15

ribosomes can enter with that and do not need to rely on a 5’ cap

Question 16

Why does the Polioviral genome don’t need to acquire a 5’ cap?

Answer 16

it has an IRES that the ribosome can bind to and start translation

Question 17

For a monocistronic genome, how does the Poliovirus carry out translation for the different proteins it needs?

Answer 17

encodes a POLYPROTEIN precursor = gets cleaved and cut up to different proteins

Question 18

What is the receptor for Poliovirus?

Answer 18

CD155 (poliovirus receptor PVR)

Question 19

What are the 2 lymphoid tissues that poliovirus infects?

Answer 19

Peyer’s patches and tonsils

Question 20

Which viral proteins form a pore on the host cell membrane?

Answer 20

VP1 and VP4

Question 21

Where are Peyer’s patches found?

Answer 21

along the intestines

Question 22

Where does the injection of the Poliovirus genome occur?

Answer 22

at the cell membrane or in early endosomes after being endocytosed

Question 23

After the Poliovirus genome enters the cytoplasm, what immediately occurs?

Answer 23

VPg is removed = translation can happen efficiently

Question 24

After translation of the Poliovirus genome, what happens next?

Answer 24

polyprotein = processed via protease

Question 25

In terms of the replication process, what happens first?

Answer 25

protein products for viral RNA replication transported to membrane-bound vesicles

Question 26

During genome replication, what happens after the proteins are transported to membrane-bound vesicles?

Answer 26

VPg acts as a protein primer = make (-)ssRNA –> dsRNA –> (+)ssRNA

Question 27

Why must genome replication occur within membrane-bound vesicles?

Answer 27

due to dsRNA intermediate

Question 28

How does Poliovirus exit the cell?

Answer 28

via lysis

Question 29

What is the portal of entry of Poliovirus?

Answer 29

mouth

Question 30

What is the transmission of Poliovirus?

Answer 30

fecal-oral or oral-oral

Question 31

What percent of poliovirus infections causes mild symptoms? What are these mild symptoms?

Answer 31

4-8% = malaise, fever, flu-like, GI disturbances

Question 32

What percent of poliovirus infections cause paralysis? What are characteristics of this paralysis?

Answer 32

1-2% = flaccid paralysis leading to inflammation and destruction of neurons; paralysis can be asymmetric

Question 33

What is the defining symptom of Poliomyelitis?

Answer 33

flaccid paralysis

Question 34

What is flaccid paralysis?

Answer 34

can’t move but limbs are limpy

Question 35

What are the 3 forms of paralytic poliomyelitis?

Answer 35

spinal, bulbar, bulbospinal

Question 36

What is the spinal paralytic form of poliomyelitis?

Answer 36

when the virus infects lower spinal cord = asymmetric/symmetric paralysis due to spinal cord

Question 37

What is the bulbar paralytic form of poliomyelitis?

Answer 37

muscle weakness; cannot talk or swallow, hard time breathing = lung muscle impacted | iron-lung

Question 38

What is the bulbospinal paralytic form of poliomyelitis?

Answer 38

combination of the bulbar and spinal paralytic forms of poliomyelitis

Question 39

What is the transient viremia stage and when during the Poliovirus pathogenesis does it occur?

Answer 39

virus is in the blood for a short time | after infects and replicates initial sites of infection

Question 40

How does the virus get into the central nervous system?

Answer 40

through the blood

Question 41

Where and when did polio epidemics occur?

Answer 41

intermittently, seasonally, and more often in industrialised countries

Question 42

Why was Polio a mass public concern?

Answer 42

disease appearance was mysterious (its all of the sudden and didn’t know the cause of symptoms) and seasonal | paralyze respiratory muscles | disfiguring, crippling, and sometimes fatal

Question 43

What is the percentage of Polio infected individuals are asymptomatic?

Answer 43

95%