Sequivirus (taxid:12057)

VIRION

Non-enveloped, 25-30 nm in diameter, pseudo T=3 icosahedral capsid.

GENOME

Monopartite linear ssRNA(+) genome of about 9 kb. The 5' terminus has a genome-linked protein (VPg).

GENE EXPRESSION

The virion RNA is infectious and serves as both the genome and viral messenger RNA. The genome single (or major) ORF is translated into a polyprotein which is subsequently processed by virus-encoded proteases into functional products.

ENZYMES

• RNA-dependent RNA polymerase [RdRp]
• VPG-type capping [VPg]
• NTPase-helicase [2C]
• Polyprotein major protease (Peptidase C3) [3Cpro, 2A]

REPLICATION

CYTOPLASMIC

1. Virus penetrates into the cell.
2. Uncoating, and release of the viral genomic RNA into the cytoplasm.
3. Synthesis and proteolytic cleavage of the viral polyprotein.
4. Replication occurs in viral factories made of membrane vesicles derived from the ER. A dsRNA genome is synthesized from the genomic ssRNA(+).
5. The dsRNA genome is transcribed/replicated thereby providing viral mRNAs/new ssRNA(+) genomes.
6. Assembly of new virus particles.