VIRION
Non-enveloped, 25-30 nm in diameter, pseudo T=3 icosahedral capsid.
GENOME
Segmented, bipartite linear ssRNA(+) genome of 7 kb for RNA1 and 4.6 to 5.4 kb for RNA2. The 5' terminus has a genome-linked protein (VPg).
GENE EXPRESSION
The virion RNA are infectious and serves as both the genome and viral messenger RNA. Both RNA encode a single polyprotein which is processed to yield the mature proteins.
ENZYMES
- RNA-dependent RNA polymerase [RdRp]
- VPG-type capping [VPg]
- NTPase-helicase [Hel]
- Polyprotein major protease (Peptidase C3) [Pro]
REPLICATION
CYTOPLASMIC
- Virus penetrates into the cell.
- Uncoating, and release of the viral genomic RNA into the cytoplasm.
- Synthesis and proteolytic cleavage of the replicase polyprotein RNA-1.
- Replication occurs in viral factories made of membrane vesicles derived from the ER. A dsRNA genome is synthesized from the genomic ssRNA(+).
- The dsRNA genome is transcribed/replicated thereby providing viral mRNAs/new ssRNA(+) genomes.
- Assembly of new virus particles.
- Movement protein allows cell-to-cell movement.