''Ribozyviria'' is a

realm A realm is a community or territory over which a sovereign rules. The term is commonly used to describe a monarchical or dynastic state. A realm may also be a subdivision within an empire, if it has its own monarch, e.g. the German Empire. Etym ...

satellite A satellite or artificial satellite is an object intentionally placed into orbit in outer space. Except for passive satellites, most satellites have an electricity generation system for equipment on board, such as solar panels or radioisotope ...

nucleic acids. Established in ICTV TaxoProp 2020.012D, the realm is named after the presence of genomic and antigenomic

ribozyme Ribozymes (ribonucleic acid enzymes) are RNA molecules that have the ability to catalyze specific biochemical reactions, including RNA splicing in gene expression, similar to the action of protein enzymes. The 1982 discovery of ribozymes demonst ...

s of the ''

Deltavirus Hepatitis D is a type of viral hepatitis caused by the hepatitis delta virus (HDV). HDV is one of five known hepatitis viruses: A, B, C, D, and E. HDV is considered to be a satellite (a type of subviral agent) because it can propagate only in ...

'' type. Additional common features include a rod-like structure, a RNA-binding "delta antigen" encoded in the genome, and animal hosts. Furthermore, the size range of the genomes of these viruses is between around 1547–1735nt, they encode a

hammerhead ribozyme The hammerhead ribozyme is an RNA motif that catalyzes reversible cleavage and ligation reactions at a specific site within an RNA molecule. It is one of several catalytic RNAs (ribozymes) known to occur in nature. It serves as a model system for ...

or a

hepatitis delta virus ribozyme The hepatitis delta virus (HDV) ribozyme is a non-coding RNA found in the hepatitis delta virus that is necessary for viral replication and is the only known human virus that utilizes ribozyme activity to infect its host. The ribozyme acts to pr ...

, and their coding capacity only involves one conserved protein. Most lineages of this realm are poorly understood, the notable exception being members of the genus ''Deltavirus'', the causal agents of

Hepatitis D Hepatitis D is a type of viral hepatitis caused by the hepatitis delta virus (HDV). HDV is one of five known hepatitis viruses: A, B, C, D, and E. HDV is considered to be a satellite (a type of subviral agent) because it can propagate only in ...

in humans. This realm of viruses have an unclear origin. They may have derived from retrozymes (a family of

retrotransposons Retrotransposons (also called Class I transposable elements or transposons via RNA intermediates) are a type of genetic component that copy and paste themselves into different genomic locations (transposon) by converting RNA back into DNA through ...

) or one of the other groups of

mobile genetic elements Mobile genetic elements (MGEs) sometimes called selfish genetic elements are a type of genetic material that can move around within a genome, or that can be transferred from one species or replicon to another. MGEs are found in all organisms. In ...

that descended from retrozymes (i.e.

viroids Viroids are small single-stranded, circular RNAs that are infectious pathogens. Unlike viruses, they have no protein coating. All known viroids are inhabitants of angiosperms (flowering plants), and most cause diseases, whose respective economi ...

and satellites). But it was also proposed that they may have originated from

with capsid protein capture.

Taxonomy

Historical development

The first

taxa In biology, a taxon (back-formation from ''taxonomy''; plural taxa) is a group of one or more populations of an organism or organisms seen by taxonomists to form a unit. Although neither is required, a taxon is usually known by a particular nam ...

of this realm to receive acceptance by the ICTV is the species ''Hepatitis delta virus'' and its genus ''Deltavirus'', in 1993. ''Deltavirus'' remained unassigned to any higher taxa until 2018, when the ICTV mistakenly classified ''Deltavirus'' within the then newly established realm, ''

Riboviria ''Riboviria'' is a realm of viruses that includes all viruses that use a homologous RNA-dependent polymerase for replication. It includes RNA viruses that encode an RNA-dependent RNA polymerase, as well as reverse-transcribing viruses (with eithe ...

''. In 2019, this error was rectified and ''Deltavirus'' returned to its original position. In 2020, ''Hepatitis delta virus'' was abolished and replaced with eight new species, and the taxonomy developed to reach its current form, detailed below.

Current status

''Ribozyviria'' contains a single family, ''Kolmioviridae'', with no intermediate taxa between realm and family. This family contains eight genera. The names of all genera in this realm allude to the letter "D" in various languages. The family name comes from

Finnish Finnish may refer to: * Something or someone from, or related to Finland * Culture of Finland * Finnish people or Finns, the primary ethnic group in Finland * Finnish language, the national language of the Finnish people * Finnish cuisine See also ...

''kolmio'' "triangle"; another reference to the Greek letter "Δ" (delta). This taxonomy is shown hereafter: * Realm: ''Ribozyviria'' ** Family: ''Kolmioviridae'' *** Genus: ''

Daazvirus ''Daazvirus'' is a genus of viruses in the realm ''Ribozyviria ''Ribozyviria'' is a realm of satellite nucleic acids. Established in ICTV TaxoProp 2020.012D, the realm is named after the presence of genomic and antigenomic ribozymes of the ...

'' **** Species: ''Daazvirus cynopis'' hinese fire belly newt virus 1 (CFBNV-1), formerly amHDV(host: '' Cynops orientalis'') *** Genus: ''

Dagazvirus ''Dagazvirus'' is a genus of viruses in the realm ''Ribozyviria ''Ribozyviria'' is a realm of satellite nucleic acids. Established in ICTV TaxoProp 2020.012D, the realm is named after the presence of genomic and antigenomic ribozymes of the ...

'' **** Species: ''Dagazvirus schedorhinotermitis'' hinotermitid virus 1 (RTV-1), rHDV(host: '' Schedorhinotermes intermedius'') *** Genus: ''

Daletvirus ''Daletvirus'' is a genus of viruses in the realm ''Ribozyviria'', containing the single species ''Daletvirus boae''. Host ''Boa constrictor The boa constrictor (scientific name also ''Boa constrictor''), also called the red-tailed boa, i ...

'' **** Species: ''Daletvirus boae'' wiss snake colony virus 1 (SwSCV-1), formerly sHDV(host: ''

Boa constrictor The boa constrictor (scientific name also ''Boa constrictor''), also called the red-tailed boa, is a species of large, non-venomous, heavy-bodied snake that is frequently kept and bred in captivity. The boa constrictor is a member of the family B ...

'', ''

Liasis mackloti savuensis ''Liasis mackloti savuensis'', known as the Savu python, is a python subspecies found in Indonesia. It is known by the locals as ''sanca mata putih'' (white-eyed python). Distribution and habitat The type locality given is " Savu Id." (=Sawoe ...

'') *** Genus: ''

Dalvirus ''Dalvirus'' is a genus of viruses in the realm ''Ribozyviria ''Ribozyviria'' is a realm of satellite nucleic acids. Established in ICTV TaxoProp 2020.012D, the realm is named after the presence of genomic and antigenomic ribozymes of the ' ...

'' **** Species: ''Dalvirus anatis'' abbling duck virus 1 (DabDV-1), formerly avHDV(host: ''

Anas gracilis The grey teal (''Anas gracilis'') is a dabbling duck found in open wetlands in Australia and New Zealand. Description It can be identified due to the presence of a crimson coloured iris in its eyes.Winter, M. (2018). Grey Teal. Wilderness Mag ...

'', '' A. castanea'', '' A. superciliosa'') *** Genus: ''

Deevirus ''Deevirus'' is a genus of viruses in the realm ''Ribozyviria ''Ribozyviria'' is a realm of satellite nucleic acids. Established in ICTV TaxoProp 2020.012D, the realm is named after the presence of genomic and antigenomic ribozymes of the ' ...

'' **** Species: ''Deevirus actinopterygii'' ay-finned fish virus 1 (RFFV-1), formerly fHDV(host: various

Actinopterygii Actinopterygii (; ), members of which are known as ray-finned fishes, is a class of bony fish. They comprise over 50% of living vertebrate species. The ray-finned fishes are so called because their fins are webs of skin supported by bony or h ...

spp.) *** Genus: ''

'' **** Species: ''Deltavirus cameroonense'' uman hepatitis delta virus 7 (HDV-7)(host: ''

Homo sapiens Humans (''Homo sapiens'') are the most abundant and widespread species of primate, characterized by bipedalism and exceptional cognitive skills due to a large and complex brain. This has enabled the development of advanced tools, culture, ...

'') **** Species: ''Deltavirus carense'' uman hepatitis delta virus 6 (HDV-6)(host: ''H. sapiens'') **** Species: ''Deltavirus italiense'' uman hepatitis delta virus 1 (HDV-1)(host: ''H. sapiens'') **** Species: ''Deltavirus japanense'' uman hepatitis delta virus 2 (HDV-2)(host: ''H. sapiens'') **** Species: ''Deltavirus peruense'' uman hepatitis delta virus 3 (HDV-3)(host: ''H. sapiens'') **** Species: ''Deltavirus senegalense'' uman hepatitis delta virus 8 (HDV-8)(host: ''H. sapiens'') **** Species: ''Deltavirus taiwanense'' uman hepatitis delta virus 4 (HDV-4)(host: ''H. sapiens'') **** Species: ''Deltavirus togense'' uman hepatitis delta virus 5 (HDV-5)(host: ''H. sapiens'') *** Genus: '' Dobrovirus'' **** Species: ''Dobrovirus bufonis'' husan Island toad virus 1 (CITV-1), formerly tfHDV(host: ''

Bufo gargarizans The Asiatic toad or Chusan Island toad (''Bufo gargarizans'') is a species of toad endemic to East Asia. The species was previously classified as ''Bufo bufo gargarizans'', a subspecies of the common toad. Distribution and habitat It is comm ...

'') *** Genus: '' Thurisazvirus'' **** Species: ''Thurisazvirus myis'' ome's spiny-rat virus 1 (TSRV-1), formerly RDev(host: ''

Proechimys semispinosus Tome's spiny rat (''Proechimys semispinosus''), also known as Tomes' spiny rat or the Central American spiny rat, is a species of spiny rat distributed from Honduras to Ecuador. The IUCN has assessed its conservation status as being of "least ...

'')

Taxonomy

Historical development

Current status

See also

References

Further reading