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 6.6 to 8.3 kb encoding for 2 successive ORFs.
GENE EXPRESSION
The presence of a RNA pseudoknot suggest that the translation of a the capsid ORF can be fused with RdRp ORF through ribosomal frameshift. There are presumably maturated by cleavage because experimentally the viral genome produces the capsid, RdRp and three smaller proteins.
ENZYMES
- RNA-directed RNA polymerase [RdRp]
- No capping activity [IRES?]
REPLICATION
CYTOPLASMIC
- Virus penetrates into the cytoplasm.
- 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.
- (+)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.
- Mature virions are transmitted to new cell by cytoplasmic exchange, sporogenesis or Hyphal anastomosis.