Written by the Fiveable Content Team • Last updated September 2025
Written by the Fiveable Content Team • Last updated September 2025
Definition
Virusoids are subviral particles composed of circular single-stranded RNA that depend on helper viruses for replication. They do not encode proteins and rely entirely on the host's cellular machinery and a helper virus for their lifecycle.
5 Must Know Facts For Your Next Test
Virusoids are classified as satellite RNAs since they require a helper virus for replication.
Unlike viroids, virusoids need a co-infecting virus to propagate within host cells.
The RNA genome of virusoids is circular and single-stranded, similar to viroids.
Virusoids do not encode any proteins; their RNA acts solely as a genetic element.
They are mostly associated with plant diseases, but their study helps understand RNA-based pathogens in general.
An infectious agent consisting of an abnormal form of a protein that can trigger normal proteins in the brain to fold abnormally.
Helper Virus: A virus that provides necessary functions for the replication or transmission of another viral entity such as a satellite or defective virus.