VIRION
Enveloped, bacilliform, about 100 nm in length and 50 nm in width.The two genomic RNAs are represented in the same particle, although this is not certain.
GENOME
Segmented, bipartite, linear, ssRNA(+) genome. The two segments are about 8.7 and 5 kb in size. The genomic RNA is capped, and polyadenylated.
GENE EXPRESSION
Genomic RNAs serve as messenger RNAs. RNA1 contains 2 ORFs, the first one encoding the replicase. RNA2 contains 4 ORFs, and may encode a movement proteins.
ENZYMES
- RNA-dependent RNA polymerase [Q1KZ59]
- Polyprotein major protease [Q1KZ59]
- Alpha-type capping [Q1KZ59]
REPLICATION
CYTOPLASMIC
- Virus penetrates into the host cell.
- Uncoating, and release of the viral genomic RNA into the cytoplasm.
- The viral RNA is translated to produce the two proteins necessary for RNA synthesis (replication and transcription).
- Replication takes place in cytoplasmic viral factories. A dsRNA genome is synthesized from the genomic ssRNA(+).
- The dsRNA genome is transcribed/replicated thereby providing viral mRNAs/new ssRNA(+) genomes.
- Expression of the subgenomic RNAs (sgRNAs).
- Each segment is encapsidated.
- Viral movement proteins probably mediate virion cell-to-cell transfer.