Norovirus (taxid:142786)



Non-enveloped, capsid of about 38-40 nm in diameter, with T=3 icosahedral symmetry. The capsid is composed of 180 VP1 proteins. Small empty virions are about 23nm in diameter, and would be of T=1 icosahedral symmetry, composed of 60 VP1 proteins.



Monopartite, linear ssRNA(+) genome of 7.3 to 8.3 kb. The 5'-terminus is linked to a VPg protein and the 3'-terminus has a poly(A) tract.n (VPg)is covalently linked to genome, whereas 3'-terminus is polyadenylated.


The virion RNA is infectious and serves as both genome and viral messenger RNA. Cleavage of ORF1 polyprotein by the virus-encoded 3C-like cysteine proteinase yields the mature nonstructural proteins. Subgenomic RNA encodes the capsid protein and VP2 minor structural protein which is expressed through RNA termination-reinitiation. Murine norovirus express an alternative ORF from the CP mRNA by leaky scanning.




  1. Attachement to host receptors mediates clathrin- and caveolin-independent endocytosis of the virus.
  2. Uncoating, and release of the viral genomic RNA into the cytoplasm.
  3. VPg is removed from the viral RNA, which is then translated into a processed ORF1 polyprotein to yield the replication proteins.
  4. Replication occurs in viral factories. A dsRNA genome is synthesized from the genomic ssRNA(+).
  5. The dsRNA genome is transcribed/replicated thereby providing viral mRNAs/new ssRNA(+) genomes.
  6. Subgenomic RNA translation gives rise to the capsid protein and VP2.
  7. Assembly of new virus particles and release by cell lysis.

Host-virus interaction

Apoptosis modulation

Murine norovirus induces host cell apoptosis .

Host gene expression shutoff by virus

Noroviruses mediate host translation shutoff by cleaving PABP1 .

Matching UniProtKB/Swiss-Prot entries

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9 entries grouped by strain

3 entries

Norovirus (strain Human/NoV/United States/Norwalk/1968/GI) (Hu/NV/NV/1968/US) reference strain

POLG_NVN68 Genome polyprotein [Cleaved into: Protein p48; NTPase (EC (p41); Protein p22; Viral ...
CAPSD_NVN68 Capsid protein VP1 (CP) (p59) [Cleaved into: Soluble capsid protein (Protein 30k) (p30)]
VP2_NVN68 Protein VP2 (Minor capsid protein)

3 entries

Lordsdale virus (strain GII/Human/United Kingdom/Lordsdale/1993) (Human enteric calicivirus) (Hu/NV/LD/1993/UK)

POLG_LORDV Genome polyprotein [Cleaved into: Protein p37; NTPase (EC (p40); Protein p20; Viral ...
CAPSD_LORDV Capsid protein (CP) (VP1) [Cleaved into: Soluble capsid protein]
VP2_LORDV Protein VP2 (Minor capsid protein)

3 entries

Southampton virus (strain GI/Human/United Kingdom/Southampton/1991) (SHV) (Hu/NV/SHV/1991/UK)

POLG_SOUV3 Genome polyprotein [Cleaved into: Protein p48; NTPase (EC (p41); Protein p22; Viral ...
CAPSD_SOUV3 Capsid protein VP1 (CP) [Cleaved into: Soluble capsid protein]
VP2_SOUV3 Protein VP2 (Minor capsid protein)