Editing Virus classification (section)

==Subviral agents==

[[Infectious agent]]s are smaller than viruses and have only some of their properties.<ref name="subviral">{{cite web |work=ICTV 9th Report (2011) |title=Subviral Agents |url=https://talk.ictvonline.org/ictv-reports/ictv_9th_report/sub-viral-agents-2011/ |access-date=2020-06-15 |publisher=International Committee on Taxonomy of Viruses |url-status=dead |archive-url=https://web.archive.org/web/20220707080238/https://talk.ictvonline.org/ictv-reports/ictv_9th_report/sub-viral-agents-2011/ |archive-date= Jul 7, 2022 }} Updated version in sync with current release: {{cite web |title=Subviral Agents |url=https://talk.ictvonline.org/ictv-reports/ictv_online_report/subviral-agents/ |url-status=dead |archive-url=https://web.archive.org/web/20220702011937/https://talk.ictvonline.org/ictv-reports/ictv_online_report/subviral-agents/ |archive-date=Jul 2, 2022 |work=10th Report |publisher=International Committee on Taxonomy of Viruses}}</ref><ref name="STRAUSS STRAUSS 2008 pp. 345–368">{{cite book | last1=Strauss | first1=James H. | last2=Strauss | first2=Ellen G. | title=Viruses and Human Disease | chapter=Subviral Agents | publisher=Elsevier | year=2008 | isbn=978-0-12-373741-0 | doi=10.1016/b978-0-12-373741-0.50012-x | pages=345–368| s2cid=80872659 |doi-access=free }}</ref> Since 2015, the ICTV has allowed them to be classified in a similar way as viruses are.<ref>TaxoProp 2015.002aG</ref>

===Viroids and virus-dependent agents===

====Viroids====

{{main|Viroid}}
* Family ''[[Avsunviroidae]]''<ref>{{cite web |last1=Di Serio |first1=Francesco |last2=Li |first2=Shi-Fang |last3=Matoušek |first3=Jaroslav |last4=Owens |first4=Robert A. |last5=Pallás |first5=Vicente |last6=Randles |first6=John W. |last7=Sano |first7=Teruo |last8=Verhoeven |first8=Jacobus Th. J. |last9=Vidalakis |first9=Georgios |last10=Flores |first10=Ricardo |publisher=ICTV |title=Family: ''Avsunviroidae''|url=https://ictv.global/report/chapter/avsunviroidae/avsunviroidae |website=The 10th ICTV Report on Virus Classification and Taxon Nomenclature |date=June 2020 |access-date=16 January 2023}}</ref>
** Genus ''[[Avsunviroid]]''; [[type species]]: ''[[Avocado sunblotch viroid]]''
** Genus ''[[Pelamoviroid]]''; type species: ''[[Peach latent mosaic viroid]]''
** Genus ''[[Elaviroid]]''; type species: ''[[Eggplant latent viroid]]''
* Family ''[[Pospiviroidae]]''<ref>{{cite web |last1=Di Serio |first1=Francesco |last2=Owens |first2=Robert A. |last3=Li |first3=Shi-Fang |last4=Matoušek |first4=Jaroslav |last5=Pallás |first5=Vicente |last6=Randles |first6=John W. |last7=Sano |first7=Teruo |last8=Verhoeven |first8=Jacobus Th. J. |last9=Vidalakis |first9=Georgios |last10=Flores |first10=Ricardo |publisher=ICTV |title=Family: ''Pospiviroidae''|url=https://ictv.global/report/chapter/pospiviroidae/pospiviroidae |website=The 10th ICTV Report on Virus Classification and Taxon Nomenclature |date=November 2020 |access-date=16 January 2023}}</ref>
** Genus ''[[Pospiviroid]]''; type species: ''[[Potato spindle tuber viroid]]''
** Genus ''[[Hostuviroid]]''; type species: ''[[Hop stunt viroid]]''
** Genus ''[[Cocadviroid]]''; type species: ''[[Coconut cadang-cadang viroid]]''
** Genus ''[[Apscaviroid]]''; type species: ''[[Apple scar skin viroid]]''
** Genus ''[[Coleviroid]]''; type species: ''[[Coleus blumei viroid 1]]''

====Satellites====
{{main|Satellite (biology)}}
Satellites depend on co-infection of a host cell with a [[helper virus]] for productive multiplication. Their nucleic acids have substantially distinct nucleotide sequences from either their helper virus or host. When a satellite subviral agent encodes the coat protein in which it is encapsulated, it is then called a satellite virus.

Satellite-like nucleic acids resemble satellite nucleic acids, in that they replicate with the aid of helper viruses. However they differ in that they can encode functions that can contribute to the success of their helper viruses; while they are sometimes considered to be genomic elements of their helper viruses, they are not always found within their helper viruses.<ref name="subviral"/>
* Satellite viruses<ref>{{cite journal |last1=Krupovic |first1=Mart |last2=Kuhn |first2=Jens H. |last3=Fischer |first3=Matthias G. |title=A classification system for virophages and satellite viruses |journal=Archives of Virology |date=7 October 2015 |volume=161 |issue=1 |pages=233–247 |doi=10.1007/s00705-015-2622-9|doi-access=free |pmid=26446887 |hdl=11858/00-001M-0000-0028-DC34-F |hdl-access=free }}</ref>
** Single-stranded [[RNA]] satellite viruses
*** (unnamed family)
**** ''[[Aumaivirus]]'' – ''[[Maize white line mosaic satellite virus]]''
**** ''[[Papanivirus]]'' – ''[[Panicum mosaic satellite virus]]''
**** ''[[Virtovirus]]'' – ''[[Tobacco mosaic satellite virus]]''
**** ''[[Albetovirus]]'' – ''[[Tobacco necrosis satellite virus]]''
*** Family ''[[Sarthroviridae]]''
**** ''[[Macronovirus]]'' – ''[[Macrobrachium satellite virus 1]]'' (extra small virus)
*** (unnamed genus) – ''[[Nilaparvata lugens commensal X virus]]''
*** (unnamed genus) – ''[[Chronic bee-paralysis satellite virus]]''
** Double-stranded [[DNA]] satellite viruses
*** Family ''[[Lavidaviridae]]'' – Virophages
** Single-stranded [[DNA]] satellite viruses
*** Genus ''[[Dependoparvovirus]]'' – [[Adeno-associated virus]] group
* Satellite nucleic acids
** Single-stranded satellite DNAs
*** Family [[Alphasatellitidae]] (encoding a replication initiator protein)
*** Family [[Tolecusatellitidae]] (encoding a pathogenicity determinant βC1)
** Double-stranded satellite RNAs
** Single-stranded satellite RNAs
*** Subgroup 1: Large satellite RNAs
*** Subgroup 2: Small linear satellite RNAs
*** Subgroup 3: Circular satellite RNAs ([[virusoid]]s)
*** Genus ''[[Deltavirus]]''
*** [[Polerovirus]]-associated RNAs
** Satellite-like RNA
** Satellite-like DNA

====Defective interfering particles====
{{main|Defective interfering particle}}

Defective interfering particles are defective viruses that have lost their ability to replicate except in the presence of a helper virus, which is normally the parental virus. They can also interfere with the helper virus.
* Defective interfering particles (RNA)
* Defective interfering particles (DNA)

=== Viriforms ===
Viriforms are a polyphyletic category of [[endogenous viral element]]s. Sometime in their evolution, they became "domesticated" by their host as a key part of the host's lifecycle. The prototypical example is members of the (also polyphyletic) ''[[Polydnaviriformidae]]'', which are used by wasps to send pieces of immunity-blunting DNA into the prey by packing them into [[virus-like particle|virion-like particles]]. Other members are so-called [[gene transfer agent]]s (GTAs) found among prokaryotes. GTA particles resemble [[Caudoviricetes|tailed phages]], but are smaller and carry mostly random pieces of host DNA. GTAs are produced by the host in times of stress; releasing GTAs kills the host cell, but allows pieces of its genetic material to live on in other bacteria, usually of the same species.<ref>{{cite journal |last1=Kuhn |first1=JH |last2=Koonin |first2=EV |title=Viriforms-A New Category of Classifiable Virus-Derived Genetic Elements. |journal=Biomolecules |date=3 February 2023 |volume=13 |issue=2 |page=289 |doi=10.3390/biom13020289 |pmid=36830658 |pmc=9953437 |doi-access=free}}</ref> The three known clades of GTAs, ''[[Rhodogtaviriformidae]]'', ''[[Bartogtaviriformidae]]'', and ''[[Brachygtaviriformidae]]'', all arose independently from different parts of the ''[[Caudoviricetes]]'' family tree.<ref>{{cite journal |last1=Kogay |first1=R |last2=Koppenhöfer |first2=S |last3=Beatty |first3=JT |last4=Kuhn |first4=JH |last5=Lang |first5=AS |last6=Zhaxybayeva |first6=O |title=Formal recognition and classification of gene transfer agents as viriforms. |journal=Virus Evolution |date=2022 |volume=8 |issue=2 |pages=veac100 |doi=10.1093/ve/veac100 |pmid=36381234 |pmc=9662315}}</ref>