Alphavirus

VIRION

Enveloped, spherical, icosahedral, 65-70nm in diameter, capsid with a T=4 icosahedral symmetry made of 240 monomers. The envelope contains 80 spikes, each spike are trimer of E1/E2 proteins.

GENOME

Monopartite, linear, ssRNA(+) genome of 11-12 kb. The genome is capped and polyadenylated.

GENE EXPRESSION

The virion RNA is infectious and serves as both genome and viral messenger RNA. The whole genome is translated into a non-structural polyprotein which is processed by host and viral proteases. RdRp is expressed by suppression of termination at the end of 10% of nsP polyproteins. In late phase of infection, structural polyprotein is expressed through a subgenomic mRNA. The mRNA contains a Downstream Hairpin Loop (DLP)to avoid the translation shutoff induced by the host PKR in the late phase of infection.

REPLICATION

CYTOPLASMIC

  1. Attachement of the viral E glycoprotein to host receptors mediates clathrin-mediated endocytosis of virus into the host cell.
  2. Fusion of virus membrane with host endosomal membrane. RNA genome is released into the cytoplasm.
  3. The positive-sense genomic ssRNA is translated into a polyprotein, which is cleaved into non-structural proteins necessary for RNA synthesis (replication and transcription).
  4. Replication takes place in cytoplasmic viral factories at the surface of endosomes. A dsRNA genome is synthesized from the genomic ssRNA(+).
  5. The dsRNA genome is transcribed/replicated thereby providing viral mRNAs/new ssRNA(+) genomes.
  6. Expression of the subgenomic RNA (sgRNA) gives rise to the structural proteins.
  7. Virus assembly occurs at the endoplasmic reticulum.
  8. Virions bud at the endoplasmic reticulum, are transported to the Golgi apparatus, and then exit the cell via the secretory pathway.
h2. Host-virus interaction Chikungunya probably activates an autophagic process which promotes viral replication .

Host gene expression shutoff by virus

Togaviruses mediate host translation shutoff.
Alphaviruses induce strong PKR activation leading to leading to the almost complete phosphorylation of eIF2alpha and host translation arrest .

Alphaviruses perform host transcription shutoff by inhibiting host RNA polymerase II. Host RNA-pol II catalytic subunit is targeted for degradation as early as 4-6h p.i. .

Matching UniProtKB/Swiss-Prot entries

56 entries grouped by strain (browse by keywords)

All proteins are shown (view only 48 complete proteome entries)

2 entries

Chikungunya virus (strain S27-African prototype) (CHIKV) reference strain

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POLN_CHIKSNon-structural polyprotein (Polyprotein nsP1234) (P1234)
POLS_CHIKSStructural polyprotein (p130)

2 entries

Semliki forest virus (SFV) reference strain

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POLN_SFVNon-structural polyprotein (Polyprotein nsP1234) (P1234)
POLS_SFVStructural polyprotein (p130)

2 entries

Sindbis virus (SINV) reference strain

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POLN_SINDVNon-structural polyprotein (Polyprotein nsP1234) (P1234)
POLS_SINDVStructural polyprotein (p130)

2 entries

Aura virus (AURAV)

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POLN_AURAVNon-structural polyprotein (Polyprotein nsP1234) (P1234)
POLS_AURAVStructural polyprotein (p130)

2 entries

Barmah forest virus (BFV)

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POLN_BFVNon-structural polyprotein (Polyprotein nsP1234) (P1234)
POLS_BFVStructural polyprotein (p130)

2 entries

Chikungunya virus (strain 37997) (CHIKV)

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POLN_CHIK3Non-structural polyprotein (Polyprotein nsP1234) (P1234)
POLS_CHIK3Structural polyprotein (p130)

2 entries

Eastern equine encephalitis virus (strain Florida 91-469) (EEEV) (Eastern equine encephalomyelitis virus)

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POLN_EEEVFNon-structural polyprotein (Polyprotein nsP1234) (P1234)
POLS_EEEVFStructural polyprotein (p130)

2 entries

Eastern equine encephalitis virus (strain PE-0.0155) (EEEV) (Eastern equine encephalomyelitis virus)

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POLN_EEEV1Non-structural polyprotein (Polyprotein nsP1234) (P1234)
POLS_EEEV1Structural polyprotein (p130)

2 entries

Eastern equine encephalitis virus (strain PE-3.0815) (EEEV) (Eastern equine encephalomyelitis virus)

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POLN_EEEV8Non-structural polyprotein (Polyprotein nsP1234) (P1234)
POLS_EEEV8Structural polyprotein (p130)

2 entries

Getah virus (GETV)

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POLN_GETVNon-structural polyprotein (Polyprotein nsP1234) (P1234)
POLS_GETVStructural polyprotein (p130)

2 entries

Mayaro virus (strain Brazil) (MAYV)

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POLN_MAYABNon-structural polyprotein (Polyprotein nsP1234) (P1234)
POLS_MAYABStructural polyprotein (p130)

2 entries

O'nyong-nyong virus (strain Gulu) (ONNV)

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POLN_ONNVGNon-structural polyprotein (Polyprotein nsP1234) (P1234)
POLS_ONNVGStructural polyprotein (p130)

2 entries

O'nyong-nyong virus (strain Igbo Ora) (ONNV) (Igbo Ora virus)

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POLN_ONNVINon-structural polyprotein (Polyprotein nsP1234) (P1234)
POLS_ONNVIStructural polyprotein (p130)

2 entries

O'nyong-nyong virus (strain SG650) (ONNV)

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POLN_ONNVSNon-structural polyprotein (Polyprotein nsP1234) (P1234)
POLS_ONNVSStructural polyprotein (p130)

2 entries

Ross river virus (strain NB5092) (RRV)

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POLN_RRVNNon-structural polyprotein (Polyprotein nsP1234) (P1234)
POLS_RRVNStructural polyprotein (p130)

2 entries

Sagiyama virus (SAGV)

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POLN_SAGVNon-structural polyprotein (Polyprotein nsP1234) (P1234)
POLS_SAGVStructural polyprotein (p130)

2 entries

Salmon pancreas disease virus (SPDV)

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POLN_SPDVNon-structural polyprotein (Polyprotein nsP1234) (P1234)
POLS_SPDVStructural polyprotein (p130)

2 entries

Sindbis virus subtype Ockelbo (strain Edsbyn 82-5) (OCKV) (Ockelbo virus)

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POLN_SINDONon-structural polyprotein (Polyprotein nsP1234) (P1234)
POLS_SINDOStructural polyprotein (p130)

2 entries

Sleeping disease virus (SDV)

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POLN_SLDVNon-structural polyprotein (Polyprotein nsP1234) (P1234)
POLS_SLDVStructural polyprotein (p130)

2 entries

Venezuelan equine encephalitis virus (strain 3880) (VEEV)

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POLN_EEVV3Non-structural polyprotein (Polyprotein nsP1234) (P1234)
POLS_EEVV3Structural polyprotein (p130)

2 entries

Venezuelan equine encephalitis virus (strain Mena II) (VEEV)

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POLN_EEVVMNon-structural polyprotein (Polyprotein nsP1234) (P1234)
POLS_EEVVMStructural polyprotein (p130)

2 entries

Venezuelan equine encephalitis virus (strain P676) (VEEV)

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POLN_EEVVPNon-structural polyprotein (Polyprotein nsP1234) (P1234)
POLS_EEVVPStructural polyprotein (p130)

2 entries

Venezuelan equine encephalitis virus (strain Trinidad donkey) (VEEV)

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POLN_EEVVTNon-structural polyprotein (Polyprotein nsP1234) (P1234)
POLS_EEVVTStructural polyprotein (p130)

2 entries

Western equine encephalitis virus (WEEV)

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POLN_WEEVNon-structural polyprotein (Polyprotein nsP1234) (P1234)
POLS_WEEVStructural polyprotein (p130)

1 entry

Chikungunya virus (strain Nagpur) (CHIKV)


POLS_CHIKNStructural polyprotein (p130)

1 entry

Eastern equine encephalitis virus (EEEV) (Eastern equine encephalomyelitis virus)


POLS_EEEVStructural polyprotein (p130)

1 entry

Eastern equine encephalitis virus (strain va33[ten broeck]) (EEEV) (Eastern equine encephalomyelitis virus)


POLS_EEEV3Structural polyprotein (p130)

1 entry

Middelburg virus


POLS_MIDDVStructural polyprotein (p130)

1 entry

Ross river virus (strain T48) (RRV)


POLS_RRVTStructural polyprotein (p130)

1 entry

Venezuelan equine encephalitis virus (strain CPA201) (VEEV)


POLN_EEVVCNon-structural polyprotein (Polyprotein nsP1234) (P1234)

1 entry

Venezuelan equine encephalitis virus (strain Everglades Fe3-7c) (VEEV)


POLS_EEVVEStructural polyprotein (p130)

1 entry

Venezuelan equine encephalitis virus (strain TC-83) (VEEV)


POLS_EEVV8Structural polyprotein (p130)