Virions have rod-shaped particles with modal lengths of 320-360 nm and diameters of 18 nm. They do not have an envelope structure.
The genome is segmented; bipartite. After deproteinization of purified virions, both single stranded and double stranded RNA are detected.
These viruses contain a single coat protein (CP) with an Mr of approximately 48 kDa and do not possess an envelope structure.