VIRION
Non enveloped, capsid with T=2* icosahedral symmetry, 35-40 nm in diameter 
.
GENOME
Segmented linear dsRNA genome: 2 segments encode for 4 proteins. Segments size range from 1.7 to 2.5 kb. Genome total size is about 4 kb.
GENE EXPRESSION
Genomic segment A encodes for a polyprotein (ORF1) that self-cleaves to yield the mature coat protein and a large peptide. Also encodes another protein (ORF2).
Genomic segment B encodes for the RNA-dependent RNA polymerase.
ENZYMES
- RNA-dependent RNA polymerase [RdRp]
- Self-cleavage, Virion maturation (Peptidase N5) [Capsid precursor]
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, inside which they are transcribed to give RNA (-) molecules with which they become base-paired to produce dsRNA genomes.
- Mature virions are released by budding.