Virusoid

Virusoids are circular single-stranded RNAs dependent on plant viruses for replication and encapsidation.^[1] The genome of virusoids consist of several hundred nucleotides and does not code for any proteins.

Virusoids are essentially viroids that have been encapsulated by a helper virus coat protein. They are thus similar to viroids in their means of replication (rolling circle replication) and due to the lack of genes, but they differ in that viroids do not possess a protein coat.

Virusoids, while being studied in virology, are subviral particles rather than viruses. 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.

References

^ Symons RH (1991). "The intriguing viroids and virusoids: what is their information content and how did they evolve?" (PDF). Mol. Plant Microbe Interact. 4 (2): 111–21. doi:10.1094/MPMI-4-111. PMID 1932808.

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[1] Symons RH (1991). "The intriguing viroids and virusoids: what is their information content and how did they evolve?" (PDF). Mol. Plant Microbe Interact. 4 (2): 111–21. doi:10.1094/MPMI-4-111. PMID 1932808.

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