VIRION
Non-enveloped, 25-30 nm in diameter, pseudo T=3 icosahedral capsid.
GENOME
Bipartite linear ssRNA(+) genome of 7 kb for RNA1 and 3.3 kb for RNA2. The 3'terminus is polyadenylated.
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.