Non-enveloped, bacilliform, about 50 nm in length and 30 nm in width, resembling those of cileviruses.


Segmented, tripartite, linear, ssRNA(+) genome. The three segments are about 8.4, 3.2 and 3.1 kb in size. The genomic RNA is capped, and polyadenylated.


Genomic RNAs serve as messenger RNAs. RNA1 contains 1 ORF encoding the replicase. RNA2 contains 4 ORFs, and may encode a movement proteins. RNA3 contains 3 ORFs.



  1. Virus penetrates into the host cell.
  2. Uncoating, and release of the viral genomic RNA into the cytoplasm.
  3. The viral RNA is translated to produce the two proteins necessary for RNA synthesis (replication and transcription).
  4. Replication takes place in cytoplasmic viral factories. A dsRNA genome is synthesized from the genomic ssRNA(+).
  5. The dsRNA genome is transcribed/replicated thereby providing viral mRNAs/new ssRNA(+) genomes.
  6. Expression of the subgenomic RNAs (sgRNAs).
  7. Each segment is encapsidated.
  8. Viral movement proteins probably mediate virion cell-to-cell transfer.