Notes on Family: Mesoniviridae
This family consists of insect-infecting nidoviruses and is placed in the order Nidovirales
, together with the families Arteriviridae
. Its name reflects the fact that the genomes in this family are intermediate (Greek, meso
= medium) in size between the small arteriviruses and the large corona- and roni-viruses.
Virions are enveloped spheres about 60-80 nm in diameter.
Monopartite positive sense single-stranded RNA about 20kb long and with a 3'-polyA tail. Two large, overlapping ORFs at the 5'-end of the genome encode the major non-structural proteins and are expressed as a fusion protein by ribosomal frameshift. Downstream are at least 4 other genes, mostly or entirely encoding structural proteins, and these are probably expressed from a 3'-coterminal nested set of subgenomic RNAs.
Genera in the Family
There is currently only one genus: