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. A truncated version of the structural polyprotein is produced by ribosomal frameshifting in the 6K region, the frameshift induces the translation of the TF protein .

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. Capsid assembly occurs in cytoplasm.
  8. The capsid is envelopped by budding at the plasma membrane where the virion exits the cell .

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

57 entries grouped by protein (browse by keywords)

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

25 entries

Non-structural polyprotein (Polyprotein nsP1234) (P1234)

Select_allDeselect_all
POLN_CHIKS
Chikungunya virus (strain S27-African prototype) (CHIKV) reference strain
POLN_SFV
Semliki forest virus (SFV) reference strain
POLN_SINDV
Sindbis virus (SINV) reference strain
POLN_AURAV
Aura virus (AURAV)
POLN_BFV
Barmah forest virus (BFV)
POLN_CHIK3
Chikungunya virus (strain 37997) (CHIKV)
POLN_EEEV1
Eastern equine encephalitis virus (strain PE-0.0155) (EEEV) (Eastern equine encephalomyelitis virus)
POLN_EEEV8
Eastern equine encephalitis virus (strain PE-3.0815) (EEEV) (Eastern equine encephalomyelitis virus)
POLN_EEEVF
Eastern equine encephalitis virus (strain Florida 91-469) (EEEV) (Eastern equine encephalomyelitis virus)
POLN_EEVV3
Venezuelan equine encephalitis virus (strain 3880) (VEEV)
POLN_EEVVC
Venezuelan equine encephalitis virus (strain CPA201) (VEEV)
POLN_EEVVM
Venezuelan equine encephalitis virus (strain Mena II) (VEEV)
POLN_EEVVP
Venezuelan equine encephalitis virus (strain P676) (VEEV)
POLN_EEVVT
Venezuelan equine encephalitis virus (strain Trinidad donkey) (VEEV)
POLN_GETV
Getah virus (GETV)
POLN_MAYAB
Mayaro virus (strain Brazil) (MAYV)
POLN_ONNVG
O'nyong-nyong virus (strain Gulu) (ONNV)
POLN_ONNVI
O'nyong-nyong virus (strain Igbo Ora) (ONNV) (Igbo Ora virus)
POLN_ONNVS
O'nyong-nyong virus (strain SG650) (ONNV)
POLN_RRVN
Ross river virus (strain NB5092) (RRV)
POLN_SAGV
Sagiyama virus (SAGV)
POLN_SINDO
Sindbis virus subtype Ockelbo (strain Edsbyn 82-5) (OCKV) (Ockelbo virus)
POLN_SLDV
Sleeping disease virus (SDV)
POLN_SPDV
Salmon pancreas disease virus (SPDV)
POLN_WEEV
Western equine encephalitis virus (WEEV)

31 entries

Structural polyprotein (p130)

Select_allDeselect_all
POLS_CHIKS
Chikungunya virus (strain S27-African prototype) (CHIKV) reference strain
POLS_SFV
Semliki forest virus (SFV) reference strain
POLS_SINDV
Sindbis virus (SINV) reference strain
POLS_AURAV
Aura virus (AURAV)
POLS_BFV
Barmah forest virus (BFV)
POLS_CHIK3
Chikungunya virus (strain 37997) (CHIKV)
POLS_CHIKN
Chikungunya virus (strain Nagpur) (CHIKV)
POLS_EEEV
Eastern equine encephalitis virus (EEEV) (Eastern equine encephalomyelitis virus)
POLS_EEEV1
Eastern equine encephalitis virus (strain PE-0.0155) (EEEV) (Eastern equine encephalomyelitis virus)
POLS_EEEV3
Eastern equine encephalitis virus (strain va33[ten broeck]) (EEEV) (Eastern equine encephalomyelitis virus)
POLS_EEEV8
Eastern equine encephalitis virus (strain PE-3.0815) (EEEV) (Eastern equine encephalomyelitis virus)
POLS_EEEVF
Eastern equine encephalitis virus (strain Florida 91-469) (EEEV) (Eastern equine encephalomyelitis virus)
POLS_EEVV3
Venezuelan equine encephalitis virus (strain 3880) (VEEV)
POLS_EEVV8
Venezuelan equine encephalitis virus (strain TC-83) (VEEV)
POLS_EEVVE
Venezuelan equine encephalitis virus (strain Everglades Fe3-7c) (VEEV)
POLS_EEVVM
Venezuelan equine encephalitis virus (strain Mena II) (VEEV)
POLS_EEVVP
Venezuelan equine encephalitis virus (strain P676) (VEEV)
POLS_EEVVT
Venezuelan equine encephalitis virus (strain Trinidad donkey) (VEEV)
POLS_GETV
Getah virus (GETV)
POLS_MAYAB
Mayaro virus (strain Brazil) (MAYV)
POLS_MIDDV
Middelburg virus
POLS_ONNVG
O'nyong-nyong virus (strain Gulu) (ONNV)
POLS_ONNVI
O'nyong-nyong virus (strain Igbo Ora) (ONNV) (Igbo Ora virus)
POLS_ONNVS
O'nyong-nyong virus (strain SG650) (ONNV)
POLS_RRVN
Ross river virus (strain NB5092) (RRV)
POLS_RRVT
Ross river virus (strain T48) (RRV)
POLS_SAGV
Sagiyama virus (SAGV)
POLS_SINDO
Sindbis virus subtype Ockelbo (strain Edsbyn 82-5) (OCKV) (Ockelbo virus)
POLS_SLDV
Sleeping disease virus (SDV)
POLS_SPDV
Salmon pancreas disease virus (SPDV)
POLS_WEEV
Western equine encephalitis virus (WEEV)

1 entry

Frameshifted structural polyprotein (p130)

POLSF_SFV
Semliki forest virus (SFV)