Molecular biology

VIRION

Non-enveloped icosahedric capsid, about 30 nm in diameter. Icosahedric symmetry is presumably T=1 but has not been determined. The two genomic segments are encapsidated separately.

GENOME

Segmented dsRNA linear genome: 2 segments encoding potentially for 2 proteins. Segments are about 1.7 and 2.0 kb each, total size about 4 kb

GENE EXPRESSION

Each genomic segment is monocistronic.

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, inside which they are transcribed to give RNA (-) molecules with which they become base-paired to produce dsRNA genomes.
4. Mature are probably transmitted to new cell during cell division.