The virions are non-enveloped and
isometric with a diameter of around 30 nm, with an
icosahedral structure and a
triangulation number T=3. The linear
genome is between of 6–7.5 kilobases in length and encodes three
open reading frames. It is capped at the 5’ terminus. The 3’ terminus may have a
tRNA-like structure or a polyA tract, depending upon the species. The genome is relatively
cytosine rich. ==Life cycle==