Sindbis Virus Flashcards
1
Q
Family
A
Togaviridae
2
Q
Genus
A
Alphavirus
3
Q
Stages
A
Attachment Pentration Uncoating Early Gene Expression Genome Replication Late Gene Expression Assembly Maturation Release
4
Q
Attachment
A
- receptor mediated (heparan sulfate)
- E2 subunit of the spike is the attachment protein
5
Q
Penetration
A
- clathrin mediated endocytosis
6
Q
Uncoating
A
- acidification of the late endosome by H+-ATPase causes a conformational change in virion (both envelope 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 starts translating ORF 1
- if opal codon not recognized (read through 10% of time) P1234 produced otherwise (90% of time) P123 produced
8
Q
Genome Replication
A
- P1234 polyprotein activated by nsP2 protease cleavage to (P123+nsP4)
- initiates (-) 49S gRNA synthesis
- complex cleaved by nsP2 protease to (nsP1+P23+nsP4).
- initiates (+/-) 49S gRNA synthesis
- complex cleaved by nsP2 protease to (nsP1+nsP2+nsP3+nsP4)
- initiates synthesis of (+) 49S gRNA
9
Q
Late Gene Expression
A
- (-) 49S gRNA transcribed to (+) 26S sgRNA and translated on free cytoplasmic ribosomes
- co-translational autocleavage by C protease exposes signal peptide
- signal peptide interacts with SRP to block further translation and dock ribosome onto RER
- 6K protein cleaved out of polypeptide by signalase
10
Q
Assembly
A
- C protein binds to (+) 49S gRNA through recognition of its OAS
- recruits more C protein to bind viral RNA completely enclosed (nucleation mechanism)
11
Q
Maturation
A
- cleavage of pE2 subunit by turin-like protease in trans-Golgi
- mature spike timers trafficked from Golgi to plasma membrane through transport vesicles
12
Q
Release
A
- 6K protein facilitates envelopment
- budding mechanism
