Poliovirus Flashcards
1
Q
Family
A
Picornaviridae
2
Q
Genus
A
Enterovirus
3
Q
Stages
A
Attachment, Penetration, Uncoating Gene Expression Genome Replication Assembly Maturation Release
4
Q
Attachment, Penetration, Uncoating
A
- receptor mediated attachment
- picornavirus particle attaches to host cell via canyon binding to specific receptor
- attachment triggers conformational change in the 5 fold vertex causing penetration/uncoating via direct injection of (+)sRNA into host cell cytoplasm
5
Q
Gene Expression
A
- translation
- ribosomes bind to ribosome landing pad
- single ORF encodes single polyprotein
- P1-2A translated. 2A protease co-translationally cleaves to release P1
- P2-3ABC translated. 3C protease co-translationally cleaves to release P2
- P3 translated. 3C protease post-translationally cleaves P1, P2, and P3
6
Q
Genome Replication
A
- P3 as 3D RNA polymerase
- takes place on cytoplasmic face of transport vesicles derived from ER membrane
- VPg used as a primer
- asymmetric synthesis of plus and minus strands. Need more plus than minus
- P3 binds to 3’ end of viral RNA
- 3D pol copies template and joins first nucleotide to VPg
- 3D pol stalls and must be cleaved by 3C protease in order to elongate
- 3C protease cleaves and 3D pol elongates
- when it reaches 5’ end of template it detaches and RNA synthesis terminates
7
Q
Assembly
A
- P1 folds up into nascent protomer
- 5 protomers combine to form pentamer
- pentamer binds to VPg-RNA and recruits 11 more to join to form provirion (nucleation mechanism)
8
Q
Release
A
cell lysis
9
Q
Maturation
A
VP0 cleaved to produce VP4 and VP2 inside virion.
