Ribozyviria

Kolmioviridae
Diagram of a Deltavirus virion
Virus classification Edit this classification
(unranked): Virus
Realm: Ribozyviria
Family: Kolmioviridae
Subtaxa
1 family
8 genera
15 species

See text

Ribozyviria is a realm of satellite nucleic acids — infectious agents that resemble viruses, but cannot replicate without a helper virus.[1] Established in ICTV TaxoProp 2020.012D, the realm is named after the presence of genomic and antigenomic ribozymes of the Deltavirus type. The agents in Ribozyviria are satellite nucleic acids, which are distinct from satellite viruses in that they do not encode all of their own structural proteins but require proteins from their helper viruses in order to assemble.[2] Additional common features include a rod-like structure, an RNA-binding "delta antigen" encoded in the genome, and animal hosts.[3] Furthermore, the size range of the genomes of these viruses is between around 1547–1735nt, they encode a hammerhead ribozyme or a hepatitis delta virus ribozyme, and their coding capacity only involves one conserved protein. Most lineages of this realm are poorly understood, the notable exception being the genus Deltavirus, comprising the causal agents of hepatitis D in humans.[4]

The realm Ribozyviria has an unclear evolutionary origin. It has been proposed that they may have derived from retrozymes (a family of retrotransposons) or a viroid-like element (i.e. viroids and satellites) with capsid protein capture.[4][5]

  1. ^ "Virus Taxonomy: 2020 Release". International Committee on Taxonomy of Viruses (ICTV). March 2021. Retrieved 10 May 2021.
  2. ^ Baez J. "Subcellular Life Forms". University of California, Riverside. Retrieved 2020-06-04.
  3. ^ Hepojoki J, Hetzel U, Paraskevopoulou S, Drosten C, Harrach B, Zerbini M, Koonin EV, Krupovic M, Dolja V, Kuhn JH (6 December 2020). "Create one new realm (Ribozyviria) including one new family (Kolmioviridae) including genus Deltavirus and seven new genera for a total of 15 species" (docx). International Committee on Taxonomy of Viruses (ICTV). Retrieved 27 May 2021.
  4. ^ a b Lee BD, Koonin EV (2022-01-12). "Viroids and Viroid-like Circular RNAs: Do They Descend from Primordial Replicators?". Life. 12 (1): 103. Bibcode:2022Life...12..103L. doi:10.3390/life12010103. ISSN 2075-1729. PMC 8781251. PMID 35054497.
  5. ^ Netter HJ, Barrios MH, Littlejohn M, Yuen LK (2021). "Hepatitis Delta Virus (HDV) and Delta-Like Agents: Insights Into Their Origin". Frontiers in Microbiology. 12: 1448. doi:10.3389/fmicb.2021.652962. ISSN 1664-302X. PMC 8256844. PMID 34234753.