Picornavirus Replication Flashcards
Give 5 picornaviruses
- FMDV
- Poliovirus
- Enteroviruses 71
- Cocksackie virus A16 (CAV16)
- Human rhinovirus (HRV)
What does FMDV cause?
Degradation of tongue epithelium so cattle cannot eat, even if the animal recovers their productivity does not. Endemic to Africa, Asia and South America
What are EV-A71 and CAV16?
The main causative agents in hand, foot and mouth disease.
What is hand, foot and mouth disease?
Causes a rash in children, occasionally associated with brain stem encephalitis, poliomyelitis-like disease and death.
Why don’t you see RNA duplexes?
Other proteins in the reaction complex keep the strands apart
What is the genome organisation of FMDV?
untranslated region - structural proteins (capsid proteins) - non-structural proteins (replication complexes) - untranslated region
How is the FMDV polyprotein processed?
Lpro is used for cleaving the capsid proteins
What cleaves capsid proteins in polio?
2A
What is the name of the protease which is used to cleave up the structural proteins in HRV?
3C
What is the RdRp in picornaviruses the product of?
The 3D gene
What is similar about the RdRps in FMDV and PV?
They are structurally conserved but not sequentially
What is the IRES important in?
Translation, not replication
Where is the CRE in polio and FMDV?
in the genome in PV and in the 5’-untranslated region in FMDV
Why does RNA circularise?
Prevent degradation by covering up free ends and increases efficiency as the polymerase just has to move around in a circle.
What is the role of the CRE?
Templates the addition of uridine residues onto VPg at the 5’-end which then acts as a primer for RdRp.
What type of VPg acts as a primer?
Uridylated
Why must translation and replication be spatially and temporally separate?
The molecular machines would crash
What removes VPg and what does it leave?
TDP2
5’-monophosphate
What is a possible reason for FMDVs rapid replication and persistence?
There are 3 copies of each primer
Replication can still occur without symptoms - silent reservoir
Give a use of the FMDV replicon?
Remove the structural proteins and replace with GFP, can visualise the RNA being made
How does polio cause paralytic poliomyelitis?
If the virus enters the blood and moves out of the gut. Results in motor neurone disease. Infection of the NS by retrograde transport along axons and passage of the virus across the BBB.
What is viremia?
Presence of virus in the blood
What are the current PV vaccines?
OPV - mutant virus
IPV - inactivated virus
When does replication occur?
Post-translationaly
