Non-enveloped, spherical virion about 34 nm in diameter with T=3 icosahedral symmetry composed of 180 CP proteins that make bumps at the surface of the virion.


Monopartite, linear, ssRNA(+) genome of 4.4 kb with a stem loop structure at the 3'-end.


The virion RNA is infectious and serves as both the genome and viral messenger RNA. ORF1 encodes the replicase and ORF2 encodes the capsid protein.



  1. Virus penetrates into the host cell.
  2. Uncoating, and release of the viral genomic RNA into the cytoplasm.
  3. The viral RNA ORF1 and ORF2 are translated.
  4. Replication takes place in cytoplasmic 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. Virus assembly.
  7. Virions accumulate in the host cytoplasm forming a crystalline array.
  8. Cell lysis and virus release.