13 GI tract2

Question 1

is picornaviridae enveloped

Answer 1

no

Question 2

what is the capsid of picornaviridae like

Answer 2

icosahedral

Question 3

what are the fold axis of symmetry in picornaviridae

Answer 3

2 fold
3 fold
5 fold

Question 4

what is pico

Answer 4

small

Question 5

what surrounds the genome in picornaviridae

Answer 5

spherical, non-enveloped capsid

Question 6

what class virus is picornaviridae

Answer 6

IV

Question 7

what RNA is picornaviridae

Answer 7

+ssRNA

Question 8

what can the picornaviridae RNA do

Answer 8

directly translate as +RNA

Question 9

what is picornaviridae like

Answer 9

• large ORF
• covalently linked protein VPg
• non-segmented

Question 10

what is the baltimore classification of picornaviridae

Answer 10

IV: +ssRNA

Question 11

what does poliovirus cause

Answer 11

paralysis

aseptic meningitis

Question 12

what is enterovirus route of transmisson

Answer 12

faecal-oral

Question 13

what are the stages of enterovirus life cycle

Answer 13

1. attachement/penetration
2. penetration
3. primary translation
4. replication (-) and (+) strand
5. secondary translation
6. assembly
7. virion exit by cell lysis

Question 14

what happens in stage 1 of enterovirus life cycle

Answer 14

• virus binds to receptor on cell

> ejection of VP4 = viral capsid structural changes

Question 15

what happens in stage 2 of enterovirus life cycle

Answer 15

• uncoating of vRNA = enters cytosol

Question 16

what happens in stage 3 of enterovirus life cycle

Answer 16

viral RNA translates proteins of poliovirus
non-capped mRNA
polyribosomes translate polyprotein, using cap-independent translation

Question 17

what is the effect of the stages in stage 3 of primary translation

Answer 17

cellular translation is blocked = translational control

lytic or fast growing viruses

Question 18

what happens in stage 4 of enterovirus life cycle

Answer 18

(+) replciation
just made (-) sense strand then serves as template for more (-) strands RNA (+ mRNA)

Question 19

what happens in stage 5 of enterovirus life cycle

Answer 19

mRNA strands serve as templates for more translation of polyprotein
some RNA packaged

Question 20

what happens in stage 6 of enterovirus life cycle

Answer 20

P1 cleaved to make VP0, VP3, VP1
If more infectious cleaves VP0 into = VP2 and VP4
RNA must be inserted in virion = packaging

Question 21

what happens in lysis of enterovirus life cycle

Answer 21

~10^5 virions per infected cell released during cell lysis

Question 22

what are the outcomes of poliovirus exposure

Answer 22

paralytic poliomyelitis
non-paralytic poliomyelitis
abortive or minor illness
unapparent infection

Question 23

what is the % of paralytic poliomyeltitis

Answer 23

0.1-2%

Question 24

what is the % of non-paralytic poliomyelitis

Answer 24

0.1-2%

Question 25

what is the % of abortive or minor illness

Answer 25

4-8%

Question 26

what is the % of unapparent infection

Answer 26

95%

Question 27

what does bulbar polio cause

Answer 27

motor neurons of brain affected | reduced breathing, difficult to speak and swallow

Question 28

what is used to aid bulbar polio

Answer 28

iron lung to aid breathing

Question 29

is enterovirus - poliovirus common

Answer 29

rare due to infant immunity

Question 30

what are the symptoms of poliovirus

Answer 30

``` fever fatigue headache vomiting sore neck some get paralytic poliovirus ```

Question 31

what has reduced passive immunity in poliovirus

Answer 31

due to plumbing - sanitation

Question 32

what leads to increase in polio cases

Answer 32

aetiology still unknown

Question 33

how is Salk PV vaccine inactivated

Answer 33

formaldehyde heat pH

Question 34

how many serotypes of salk PV vaccine are there

Answer 34

3 serotypes

Question 35

where and how is PV grown

Answer 35

in the lab | using tissue culture

Question 36

what is Salk PV also known as

Answer 36

IPV

Question 37

what is the oral enterovirus vaccine for poliovirus known as

Answer 37

sabin

Question 38

what is the sabin vaccine like

Answer 38

attenuated

Question 39

what is VAPP

Answer 39

vaccine associated paralytic poliovirus

Question 40

how effect is sabin

Answer 40

100% efficacy after three doses

Question 41

what is the affect of VAPP

Answer 41

as attenuated is live and can replicate in the gut

Question 42

what causes the attenuated mutation in poliovirus vaccine

Answer 42

in 5’ NCR (non-coding region) of PV RNA secondary structure of the poliovirus 5’ non-coding region VAPP/Attenuating mutations of PV 1-3 Mutations in domain V U would have to revert back to C to get a wildtype Exposed to wildtype poliovirus= infected

Question 43

what is the inactivated polio virus vaccine

Answer 43

Salk

Question 44

what are the advantages of inactivated dead poliovirus vaccine

Answer 44

- Safe - Can be used for immune-deficient (or suppressed) patients - High uptake - Excellent systemic immunity - No reversion, no excretion of wild-type into community

Question 45

what are the disadvantages in poliovirus inactivated vaccine

Answer 45

- Requires repeated IM injection and is more expensive - Limited mucosal/intestinal immunity compared to live - risk due to use of wt virus as seed for vaccine

Question 46

what are the attenuated poliovirus vaccine advantages

Answer 46

- Strong systemic and intestinal immunity (cannot pass through as easily) - Inexpensive - Oral delivery - Relatively safe - Herd immunity: virus is excreted into the environment

Question 47

what are the attenuated poliovirus vaccine disadvantages

Answer 47

- Can mutate to NV form (neurovirulent form) – causing VAPP - Requires monkeys for testing - Unsuitable for immunodeficient and immunosuppressed individuals (as live) - Can lead to Vaccine Derived PV leading to outbreaks cVDPV (circulating VDPV)

Question 48

why should eradication of poliovirus feasible

Answer 48

- no animal reservoirs - virus is not airborne - only three serotypes - Poliovirus entry into cells is very inefficient

Question 49

how can we eliminate poliovirus

Answer 49

stop using the attenuated vaccine | to stop VAPP