Sindbis Virus Flashcards
1
Q
Stages
A
Attachment
Penetration
Uncoating
Early Gene Expression
Genome Replication
Late Gene Expression
Maturation
Assembly
Release
2
Q
Family
A
Togaviridae
3
Q
Genus
A
Alphavirus
4
Q
Attachment
A
- receptor-mediated (heparan sulfate)
- attachment protein is E2 subunit of envelope
5
Q
Penetration
A
- Clathrin-mediated endocytosis
6
Q
Uncoating
A
- endosome acidificatioon causes conformational change in virion (both envelope spike and underlying nucleocapsid)
- E1 subunit of spike responsible for fusion or membrane penetration to form aqueous pore
7
Q
Early gene expression
A
- 40S subunit binds to 5’ cap, scans to AUG codon, and translates ORF 1
- if opal codon not recognized (read through 10% of time) P1234 produced otherwise (90%) P123 produced
8
Q
Genome replication
A
- P1234 polyprotein activated by cleavage to (P123+nsP4)
- (P123+nsP4) replicase complex binds to 3’ end (+) 49S RNA and initiates (-) 49S RNA synthesis - forms full length (-) 49S RNA strand
- complex cleaved to (nsP1+P23+nsP4) -(nsP1+P23+nsP4) complex binds to 3’ end of both (+) and (-) 49S strand - forms full length (+) and (-) 49S strands - complex cleaved
- (nsP1+nsP2+nsP3+nsP4) complex binds to both 3’ end and internal site on full length (-) 49S RNA strand - forms full length (+) 49S RNA strand and 26S RNA strand (transcription)
9
Q
Late Gene expression
A
- Transcription of 49S (-) strand by (nsP1+nsP2+nsP3+nsP4) to generate 26S (+) sRNA - translation of 26S sgRNA on free cytoplasmic ribosomes
- cotranslationally autocleavage of C exposes signal peptide
- signal peptide interact with SRP and blocks further translation and docks ribosome onto RER
- signalase cleaves 6K out of polyprotein
10
Q
Assembly
A
- C protein binds to 49S gRNA. Recognizes OAS
- addition of more C protein until viral RNA completely enclosed (nucleation mechanism)
11
Q
Maturation
A
- furin-like protease cleaves pE2 in trans-Golgi
- mature spike trimers trafficked form Golgi to plasma membrane in transport vesicles
12
Q
Release
A
- envelopment facilitated by 6K protein
- budding mechanism
