Non-enveloped virion, about 40 nm in diameter with a T=4 icosahedral symmetry (240 copies of two proteins derived from the capsid precursor cleavage). The capsid precursor is expressed from a subgenomic RNA molecule which, along with genomic RNA, can be packaged into virions.


Linear ssRNA(+) genome of 6.1 kb without a polyA tail. There are three ORFs. The replicase ORF encodes two proteins via a suppression of termination mechanism.


The virion RNA is infectious and serves as both the genome and viral messenger RNA. Genomic RNA is translated into a polyprotein which is cleaved presumably by a viral protease into replication proteins and a 130 kDa protein. Replication produces a subgenomic RNA which encodes for capsid protein.



  1. Virus penetrates into the host cell.
  3. Genomic RNA is translated to produce replication proteins.
  6. Expression of the subgenomic RNA encoding the capsid protein.
  7. Assembly of new virus particles.
  8. Virion maturation by the viral protease.