Non-enveloped, isometric, icosahedral, about 30 nm in diameter.
Linear, C-rich, ssRNA(+) genome of 7.5 kb. The 3' terminus has a poly(A) tract.
The virion RNA is infectious and serves as both the genome and viral messenger RNA. The genomic RNA encodes a large replication polyprotein which is cleaved. The capsid protein and two small proteins are translated from two or more 3'-coterminal subgenomic RNAs.
- RNA-dependent RNA polymerase [Polyprotein]
- Alpha-type capping [Polyprotein]
- Polyprotein major protease (Peptidase C21) [Polyprotein]
- Virus penetrates into the host cell.
- Uncoating, and release of the viral genomic RNA into the cytoplasm.
- The viral RNA is translated to produce the protein necessary for RNA synthesis (replication and transcription).
- Replication occurs in viral factories. A dsRNA genome is synthesized from the genomic ssRNA(+).
- The dsRNA genome is transcribed/replicated thereby providing viral mRNAs/new ssRNA(+) genomes.
- The RdRp recognizes an internal subgenomic promoter on the negative-sense RNA to transcribe the 3'co-terminal subgenomic RNA that will generate the capsid protein.
- Assembly of new virus particles.