View source for Biology:Anelloviridae

{{Short description|Family of viruses}}
{{Virusbox
| taxon              = Anelloviridae
| subdivision_ranks  = genus
| subdivision        =
(see text)
}}

'''''Anelloviridae''''' is a family of [[Biology:Virus|virus]]es. They are classified as vertebrate viruses and have a non-enveloped [[Biology:Capsid|capsid]], which is round with isometric, icosahedral symmetry and has a triangulation number of 3.

The name is derived from Italian ''anello'' 'ring', referring to the circular genome of anelloviruses. 

==Genome==

The [[Biology:Genome|genome]] is not segmented and contains a single molecule of [[Biology:CccDNA|circular]], negative-sense, single-stranded [[Biology:DNA|DNA]]. The complete genome is 3000–4000 [[Biology:Nucleotide|nucleotide]]s long.<ref>ICTVdB Management (2006). 00.107.0.01. Anellovirus. In: ICTVdB—The Universal Virus Database, version 4. Büchen-Osmond, C. (Ed), Columbia University, New York, USA</ref> They also contain a non-coding region with one to two  80–110 nt sequences that contain high GC content, forming a secondary structure of stems and loops.<ref name=":0">{{Cite book|last=Biagini|first=Philippe|title=Virus Taxon|publisher=Elsevier (London)|year=2011}}</ref> The genome has [[Biology:Open reading frame|ORFs]] and a high degree of genetic diversity.<ref>Viralzone</ref>

Although the mechanism of replication has not been studied heavily, anelloviridae appears to use the rolling circle mechanism where first ssDNA is converted to dsDNA. It requires a host polymerase for replication to occur as the genome itself does not encode for a viral polymerase and, as a result, anelloviridae must replicate inside the cell's nucleus.<ref>Viralzone</ref> 

Anelloviridae also have two main open reading frames, ORF1 and ORF2. They initiate at two different AUG codons.<ref name=":1">{{Cite journal|last1=Kaczorowska|first1=Joanna|last2=van der Hoek|first2=Lia|date=2020-05-01|title=Human anelloviruses: diverse, omnipresent and commensal members of the virome|url= |journal=FEMS Microbiology Reviews|language=en|volume=44|issue=3|pages=305–313|doi=10.1093/femsre/fuaa007|pmid=32188999|pmc=7326371|issn=0168-6445|doi-access=free}}</ref> Additional ORFs can be formed as well. These ORFs may overlap partially. <ref name=":0" />

ORF1 is thought to encode the putative capsid protein and replication-associated protein of anelloviruses. The specific role of these replication-associated proteins are still being studied.<ref>{{Cite web|title=Anelloviridae – ssDNA Viruses (2011) – ssDNA Viruses (2011) – ICTV|url=https://talk.ictvonline.org/ictv-reports/ictv_9th_report/ssdna-viruses-2011/w/ssdna_viruses/139/anelloviridae|access-date=2020-11-20|website=talk.ictvonline.org}}{{dead link|date=January 2023|bot=medic}}{{cbignore|bot=medic}}</ref> 

ORF2 is thought to either encode a protein with phosphatase activity (TTMVs) or a peptide that suppresses the NF-<math>\kappa</math>B pathways (TTVs).<ref>Zheng, H., Ye, L., Fang, X., Li, B., Wang, Y., Xiang, X., Kong, L., Wang, W., Zeng, Y., Ye, L. and Wu, Z., 2007. Torque teno virus (SANBAN Isolate) ORF2 protein suppresses NF-κB pathways via interaction with IκB kinases. Journal of virology, 81(21), pp.11917-11924.
</ref> It was seen to have a highly conserved motif in the N-terminal part.

==Clinical==

Anellovirus species are highly prevalent and genetically diverse. Their virome has been present in most humans. They enter in the cell early in life and replicate persistently.<ref>{{Cite journal|last1=Freer|first1=Giulia|last2=Maggi|first2=Fabrizio|last3=Pifferi|first3=Massimo|last4=Di Cicco|first4=Maria E.|last5=Peroni|first5=Diego G.|last6=Pistello|first6=Mauro|date=2018-04-10|title=The Virome and Its Major Component, Anellovirus, a Convoluted System Molding Human Immune Defenses and Possibly Affecting the Development of Asthma and Respiratory Diseases in Childhood|journal=Frontiers in Microbiology|volume=9|page=686|doi=10.3389/fmicb.2018.00686|issn=1664-302X|pmc=5902699|pmid=29692764|doi-access=free}}</ref> This happens in the first month of life. It remains debated whether or not the first infection is symptomatic or not, however. They are probably repressed by host immunity, as the anelloviruses increase during host immunosuppression.<ref name=":1" />

The overall prevalence in the general population is over 90% and has been found in all continents.<ref name=":0" /> They cause chronic human viral infections that have not yet been associated with disease. There is also no evidence of viral clearance following infection.<ref name=":1" /> At least 200 different species are present in humans and animals.<ref name="pmid20497515">{{cite journal |vauthors =Bernardin F, Operskalski E, Busch M, Delwart E |title=Transfusion transmission of highly prevalent commensal human viruses |journal=Transfusion |volume= 50|issue= 11|pages= 2474–2483|date=May 2010 |pmid=20497515 |doi=10.1111/j.1537-2995.2010.02699.x|s2cid=29973708 }}</ref>

It has been shown that there are multiple methods of transmission such as saliva droplets and maternal or sexual routes.<ref name=":0" />

==Taxonomy==
Most genera has a name pattern of a certain (Greek, Arabic or Hebrew) letter+torquevirus with the exception of gyrovirus, as Alphatorquevirus (where torque means necklace) is one of the first genera to represent the family. The family contains the following genera:<ref name="ICTV"> {{cite web |title=Virus Taxonomy: 2022 Release |url=https://ictv.global/taxonomy |website=International Committee on Taxonomy of Viruses (ICTV) |access-date=13 August 2023 |language=en |date=March 2023}} </ref>

{{div col}}
*''Aleptorquevirus''
*''[[Biology:Alphatorquevirus|Alphatorquevirus]]''
*''[[Biology:Betatorquevirus|Betatorquevirus]]''
*''Chitorquevirus''
*''Dalettorquevirus''
*''[[Biology:Deltatorquevirus|Deltatorquevirus]]''
*''[[Biology:Epsilontorquevirus|Epsilontorquevirus]]''
*''[[Biology:Etatorquevirus|Etatorquevirus]]''
*''[[Biology:Gammatorquevirus|Gammatorquevirus]]''
*''Gimeltorquevirus''
*''[[Biology:Gyrovirus|Gyrovirus]]''
*''Hetorquevirus''
*''[[Biology:Iotatorquevirus|Iotatorquevirus]]''
*''[[Biology:Kappatorquevirus|Kappatorquevirus]]''
*''[[Biology:Lambdatorquevirus|Lambdatorquevirus]]''
*''Mutorquevirus''
*''Nutorquevirus''
*''Omegatorquevirus''
*''Omicrontorquevirus''
*''Pitorquevirus''
*''Psitorquevirus''
*''Rhotorquevirus''
*''Sigmatorquevirus''
*''Tettorquevirus''
*''[[Biology:Thetatorquevirus|Thetatorquevirus]]''
*''Upsilontorquevirus''
*''Wawtorquevirus''
*''Xitorquevirus''
*''Zayintorquevirus''
*''[[Biology:Zetatorquevirus|Zetatorquevirus]]''
{{div col end}}

== References ==
{{Reflist|2}}

== External links ==
* {{MeshName|Anellovirus}}
* [https://www.ncbi.nlm.nih.gov/ICTVdb/ICTVdB/00.107.0.01.htm ICTVdb]
* [http://www.expasy.org/viralzone/all_by_protein/772.html Viral Zone]

{{Baltimore classification|II}}
{{Taxonbar|from=Q4761639}}

[[Category:Anelloviridae| ]]
[[Category:Virus families]]

{{Sourceattribution|Anelloviridae}}