Marnaviridae (taxid:324901)

VIRION

Non-enveloped, T=pseudo3 icosahedral capsid, about 25nm in diameter and composed of 60 trimers of VP1-VP2-VP3 proteins.

GENOME

Monopartite, linear ssRNA(+) genome about 8.6 kb in size. 3'end is polyadenylated.

GENE EXPRESSION

The virion RNA is infectious and serves as both the genome and viral messenger RNA. The polyprotein is processed presumably by several proteases.

ENZYMES

• RNA-dependent RNA polymerase [RdRp Q7T7T5]
• VPG-type capping [VPg Q7T7T5]
• NTPase-helicase [NTPase Q7T7T5]
• Polyprotein major protease (Peptidase C3) [Protease Q7T7T5]

REPLICATION

1. Virus penetrates into the host cell.
2. Uncoating, and release of the viral genomic RNA into the cytoplasm possibly through the formation of a pore in the host cell membrane.
3. Synthesis and proteolytic cleavage of the polyprotein.
4. Replication occurs in viral factories. 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 virions.
7. Virus release.