VIRION

Non-enveloped capsid presumably with T=2* icosahedral symmetry and composed of 120 protein subunit monomers. The capsid is about 40 nm in diameter.

GENOME

Linear dsRNA genome about 6.7 to 8.1 kb encoding for 2 successive ORFs.

GENE EXPRESSION

The capsid ORF may be fused with RdRp ORF through ribosomal frameshift.

ENZYMES

• RNA-directed RNA polymerase [RdRp]
• No capping activity [IRES? Cap snatching?]

REPLICATION

CYTOPLASMIC

1. Virus penetrates into the cytoplasm.
2. Transcription of the dsRNA genome by viral polymerase occurs inside the virion, so that dsRNA is never exposed to the cytoplasm. This plus-strand transcript is used as template for translation.
3. (+)RNAs are encapsidated in virion particle, in which they are transcribed to give RNA (-) molecules with which they become base-paired to produce dsRNA genomes.
4. Mature virions are transmitted to new cell by cytoplasmic exchange, sporogenesis or Hyphal anastomosis.