Circoviridae
{{Short description|Family of viruses}}
{{Use dmy dates|date=April 2017}}
{{Virusbox
| taxon = Circoviridae
| subdivision_ranks = Genera
| subdivision =
}}
Circoviridae is a family of DNA viruses.{{cite journal |doi=10.1099/jgv.0.000871 |pmid=28786778 |pmc=5656780 |title=ICTV Virus Taxonomy Profile: Circoviridae |journal=Journal of General Virology |volume=98 |issue=8 |pages=1997–1998 |year=2017|author-link1=Mya Breitbart |last1=Breitbart |first1=Mya |last2=Delwart |first2=Eric |last3=Rosario |first3=Karyna |last4=Segalés |first4=Joaquim |last5=Varsani |first5=Arvind }}{{cite web|title=ICTV Report Circoviridae|url=http://www.ictv.global/report/circoviridae}} Birds and mammals serve as natural hosts. The family has two genera. Diseases associated with this family include: PCV-2: postweaning multisystemic wasting syndrome; CAV: chicken infectious anemia.{{cite web|title=Viral Zone|url=http://viralzone.expasy.org/all_by_species/11.html|publisher=ExPASy|access-date=15 June 2015}}{{cite web |title=Virus Taxonomy: 2020 Release |url=https://ictv.global/taxonomy |publisher=International Committee on Taxonomy of Viruses (ICTV) |date=March 2021 |access-date=11 May 2021}}
Structure
Viruses in the family Circoviridae are non-enveloped, with icosahedral and round geometries, and T=1 symmetry. The diameter is around 20 nm. Genomes are circular and non-segmented, around 3.8kb in length. The capsid consists of 12 pentagonal trumpet-shaped pentamers. There are two main open reading frames arranged in opposite directions that encode the replication and capsid proteins.
| class="wikitable sortable" style="text-align:center" | |||||
| Genus | Structure || Symmetry | Capsid | Genomic arrangement | Genomic segmentation | |
|---|---|---|---|---|---|
| Cyclovirus | Icosahedral | T=1 | Non-enveloped | Circular | Monopartite |
| Circovirus | Icosahedral | T=1 | Non-enveloped | Circular | Monopartite |
Life cycle
Viral replication is nuclear. Entry into the host cell is achieved by penetration into the host cell. Replication follows the ssDNA rolling circle model. DNA templated transcription, with some alternative splicing mechanism is the method of transcription. The virus exits the host cell by nuclear egress, and nuclear pore export. A stem loop structure with a conserved nonanucleotide motif is located at the 5' intergenic region of circovirus genomes and is thought to initiate rolling-cycle replication.
Birds and mammals serve as the natural host. Transmission routes are fecal-oral.
| class="wikitable sortable" style="text-align:center" | |||||||
| Genus | Host | Tissue tropism | Entry | Release | Replication site | Assembly site | Transmission |
|---|---|---|---|---|---|---|---|
| Cyclovirus | Birds | Chicken: Thymocytes, erythrobalstoid cells; Egg: embryonal tissues and eggshell membrane | Cell receptor endocytosis | Budding | Nucleus | Nucleus | Horizontal: oral-fecal; vertical: bird to egg |
| Circovirus | Birds; pigs | None | Cell receptor endocytosis | Budding | Nucleus | Nucleus | Horizontal; oral-fecal |
Taxonomy
The family Circoviridae contains two genera—Circovirus and Cyclovirus.
Clinical
A cyclovirus—cyclovirus-Vietnam—has been isolated from the cerebrospinal fluid of 25 Vietnamese patients with CNS infections of unknown aetiology.{{cite journal |doi=10.1128/mBio.00231-13 |title=Identification of a New Cyclovirus in Cerebrospinal Fluid of Patients with Acute Central Nervous System Infections |journal=mBio |volume=4 |issue=3 |pages=e00231–13 |year=2013 |last1=Tan |first1=L. V |last2=Van Doorn |first2=H. R |last3=Nghia |first3=H. D. T |last4=Chau |first4=T. T. H |last5=Tu |first5=L. T. P |last6=De Vries |first6=M |last7=Canuti |first7=M |last8=Deijs |first8=M |last9=Jebbink |first9=M. F |last10=Baker |first10=S |last11=Bryant |first11=J. E |last12=Tham |first12=N. T |last13=Bkrong |first13=N. T. T. C |last14=Boni |first14=M. F |last15=Loi |first15=T. Q |last16=Phuong |first16=L. T |last17=Verhoeven |first17=J. T. P |last18=Crusat |first18=M |last19=Jeeninga |first19=R. E |last20=Schultsz |first20=C |last21=Chau |first21=N. V. V |last22=Hien |first22=T. T |last23=Van Der Hoek |first23=L |last24=Farrar |first24=J |last25=De Jong |first25=M. D |pmc=3684831 |pmid=23781068}} The same virus has been isolated from the faeces of healthy children and also from pigs and chickens. This suggests an orofaecal route of transmission with a possible animal reservoir.
See also
References
{{Reflist|2}}
External links
- [http://www.ictv.global/report/circoviridae ICTV Online Report; Circoviridae]
- [https://www.ncbi.nlm.nih.gov/ICTVdb/Ictv/fs_circo.htm ICTVdB Entry for Circoviridae]
- [http://viralzone.expasy.org/all_by_species/11.html Viralzone: Circoviridae]
{{Baltimore classification}}
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{{Authority control}}