Sindbis Virus Flashcards Preview

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Flashcards in Sindbis Virus Deck (12)
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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