VirusoidVirusoids are circular single-stranded RNAs dependent on plant viruses for replication and encapsidation.[1] The genome of virusoids consist of several hundred nucleotides and only encodes structural proteins.

Virusoids are similar to viroids in size, structure and means of replication (rolling-circle replication)

Virusoids, while being studied in virology, are not considered as viruses but as subviral particles. Since they depend on helper viruses, they are classified as satellites. In the virological taxonomy they appear as Satellites/Satellite nucleic acids/Subgroup 3: Circular satellite RNAs.

The term virusoid is also sometimes used more generally to refer to all satellites