Circoviridae

Genus: Cyclovirus


Genus: Cyclovirus

Distinguishing features

Cyclovirus genomes contain two major ORFs encoding the Rep and Cp. In contrast to members of the genus Circovirus, cycloviruses have the putative ori on the Cp-encoding strand (Rosario et al., 2012). In addition, cyclovirus genomes have an IR between the 5' end of major ORFs; however, the IR between the 3' ends of these ORFs is smaller than that of genomes representing the genus Circovirus or may be absent (Li et al., 2010, Delwart and Li 2012). Introns have been identified within the ORFs of several cyclovirus genomes, while none have been reported for circoviruses.

Virion

Morphology

Unknown.

Physicochemical and physical properties

Unknown.

Nucleic acid

Cycloviruses exhibit small, circular ssDNA genomes ranging approximately from 1.7 to 1.9 kb.

Proteins

Unknown.

Lipids

Unknown.

Carbohydrates

Unknown.

Genome organization and replication

Cyclovirus genomes contain two major ORFs encoding the Rep and Cp (Rosario et al., 2017). Although the virion strand has not be experimentally demonstrated for cycloviruses, knowledge from other eukaryotic Rep-encoding ssDNA viruses suggests that the strand containing the nonanucleotide motif is encapsidated (Rosario et al., 2012). Since the putative cyclovirus ori and predicted Rep share conserved features with members of the genus Circovirus, cycloviruses are also thought to replicate through RCR.  Similar to circoviruses, the putative cyclovirus ori contains the canonical nonanucleotide motif ‘NAGTATTAC’ located at the apex of a potential stem-loop structure found between the 5’ ends of major ORFs. In addition, the Rep contains endonuclease and helicase domains with RCR and SF3 motifs similar to those identified in circovirus Reps. These conserved motifs include RCR motifs I [FT(L/W)NN], II [(P/x)HLQG] and III [Y(C/l)(S/x)K] and SF3 helicase motifs Walker-A [G(P/x)(P/t)(G/x)xGKS], Walker-B [uuDDF], and motif C [uTS(N/e)], where ‘‘x’’ represents any type of residue and ‘‘u’’ represents a hydrophobic amino acid (i.e., F, I, L, V, M). Moreover, putative Rep-binding domains characterized by iterative sequences near the stem-loop structure have been identified for some cyclovirus genomes (Dayaram et al., 2013).

Antigenicity

Unknown.

Biology

Cyclovirus genomes were originally discovered in primate stool samples and meat products from diverse animals (camels, chickens, cows, goats, sheep) (Li et al., 2010, Delwart and Li 2012). However, cyclovirus genomes have now been reported from various types of human samples other than faeces, including cerebrospinal fluid, blood serum, and respiratory secretions (Smits et al., 2013, Tan le et al., 2013, Phan et al., 2014, Phan et al., 2015). Additionally, cycloviruses have been detected in sampled from a wide range of mammalian and insect species (Rosario et al., 2017). Since genomes belonging to the genus Cyclovirus have only been identified through sequence-based analyses (i.e., degenerate PCR and metagenomic sequencing), definitive hosts and biology are largely unknown.

Species demarcation criteria

The species demarcation threshold is 80% genome-wide nucleotide sequence identity based on pairwise identity distribution analysis (Figure 3.Circovirus) (Rosario et al., 2017).

Member Species

SpeciesVirus name(s)Exemplar isolateExemplar accession numberExemplar RefSeq numberAvailable sequenceOther isolatesOther isolate accession numbersVirus Abbreviation(s)
Bat associated cyclovirus 1bat faeces associated cyclovirus 1GF-4cHM228874Complete genomeBatACyV1-GF-4c
Bat associated cyclovirus 10bat associated cyclovirus 10POA/2012/6KM382270NC-025792Complete genomeBatACyV10-POA/2012/6
Bat associated cyclovirus 11bat associated cyclovirus 11BtMspp/CV/GD2012KJ641717Complete genomeBatACyV11-BtMspp/CV/GD2012
Bat associated cyclovirus 12bat associated cyclovirus 12POA/2012/IIKM382269NC_025791Complete genomeBatACyV12-POA/2012/II
Bat associated cyclovirus 13bat associated cyclovirus 13BtPa-CV-2/NX2013KJ641728Complete genomeBatACyV13-BtPa-CV-2/NX2013
Bat associated cyclovirus 14bat associated cyclovirus 14Tbat/H/103699KT732785Complete genomeBatACyV14-Tbat7H/103699
Bat associated cyclovirus 15bat associated cyclovirus 15Tbat/H/88317KT732786Complete genomeBatACyV15-Tbat/H/88317
Bat associated cyclovirus 16bat associated cyclovirus 16Tbat/K/103923KT732787Complete genomeBatACyV16-Tbat/K/103923
Bat associated cyclovirus 2bat faeces associated cyclovirus 2YN-BtCV-2JF938079Complete genomeBatACyV2-YN-BtCV-2
Bat associated cyclovirus 3bat faeces associated cyclovirus 3YN-BtCV-4JF938081Complete genomeBatACyV3-YN-BtCV-4
Bat associated cyclovirus 4bat faeces associated cyclovirus 4YN-BtCV-5JF938082Complete genomeBatACyV4-YN-BtCV-5
Bat associated cyclovirus 5bat associated cyclovirus 5CYCV-TBHQ738637NC_014929Complete genomeBatACyV5-CyCV-TB
Bat associated cyclovirus 6bat associated cyclovirus 6BtRp-CV-3/GD2012KJ641712Complete genomeBatACyV6-BtRp-CV-3/GD2012
Bat associated cyclovirus 7bat associated cyclovirus 7BtRf-CV-24/YN2010KJ641740Complete genomeBatACyV7-BtRf-CV-24/YN2010
Bat associated cyclovirus 8bat associated cyclovirus 8BtRp-CV-52/GD2012KJ641715Complete genomeBatACyV8-BtRp-CV-52/GD2012
Bat associated cyclovirus 9bat associated cyclovirus 9BtTp-CV-2/GX2012KJ641720Complete genomeBatACyV9-BtTp-CV-2/GX2012
Bovine associated cyclovirus 1bovine cyclovirusPKbeef23HQ738634Complete genomeBoACyV1-PKbeef23
Chicken associated cyclovirus 1chicken associated cyclovirus 1NGchicken8HQ738643Complete genomeChickACyV1-NGchicken8
Chimpanzee associated cyclovirus 1chimpanzee faeces associated cyclovirusChimp11GQ404849Complete genomeChimpACyV1-Chimp11
Cockroach associated cyclovirus 1Florida wood cockroach cyclovirusGS140JX569794NC_020206Complete genomeCroACyV1-GS140
Dragonfly associated cyclovirus 1dragonfly cyclovirus 1TO-DFpB1-2010JX185419Complete genomeDfACyV1-TO-DFpB1-2010
Dragonfly associated cyclovirus 2dragonfly cyclovirus 2FL1-NZ38-2010JX185422NC_023869Complete genomeDfACyV2-FL1-NZ38-2010
Dragonfly associated cyclovirus 3dragonfly cyclovirus 3FL2-5E-2010JX185424NC_023868Complete genomeDfACyV3-FL2-5E-2010
Dragonfly associated cyclovirus 4dragonfly cyclovirus 4US-DFKWGX-2012KC512916Complete genomeDfACyV4-US-DFKWGX-2012
Dragonfly associated cyclovirus 5dragonfly cyclovirus 5PR-6E-2010JX185426NC_023866Complete genomeDfACyV5-PR-6E-2010
Dragonfly associated cyclovirus 6dragonfly cyclovirus 6US-DFKWGX-2012KC512918Complete genomeDfACyV6-US-DFKWGX-2012
Dragonfly associated cyclovirus 7dragonfly cyclovirus 7NZ-DFNZ3-2011KC512919Complete genomeDfACyV7-NZ-DFNZ3-2011
Dragonfly associated cyclovirus 8dragonfly cyclovirus 8AU-DFB007B-2012KC512920Complete genomeDfACyV8-AU-DFB007B-2012
Feline associated cyclovirus 1feline cyclovirusKM017740NC_024700Complete genomeFeACyV1
Goat associated cyclovirus 1goat cyclovirusPKgoat11HQ738636NC_014928Complete genomeGoACyV1-PKgoat11
Horse associated cyclovirus 1horse cyclovirusEqu1KR902499Complete genomeHoACyV1-Equ1
Human associated cyclovirus 1human associated cyclovirus 1PK5510GQ404847Complete genomeHuACyV1-PK5510
Human associated cyclovirus 10human associated cyclovirus 107078AKF726984NC_023874Complete genomeHuACyV10-7078A
Human associated cyclovirus 11human associated cyclovirus 11SL-108277KJ831064Complete genomeHuACyV11-SL-108277
Human associated cyclovirus 2human associated cyclovirus 2PK5006GQ404844Complete genomeHuACyV2-PK5006
Human associated cyclovirus 3human associated cyclovirus 3PK5222GQ404846Complete genomeHuACyV3-PK5222
Human associated cyclovirus 4human associated cyclovirus 4TN25GQ404857Complete genomeHuACyV4-TN25
Human associated cyclovirus 5human associated cyclovirus 5PK5034GQ404845Complete genomeHuACyV5-PK5034
Human associated cyclovirus 6human associated cyclovirus 6NG12GQ404854Complete genomeHuACyV6-NG12
Human associated cyclovirus 7human associated cyclovirus 7NG14GQ404855Complete genomeHuACyV7-NG14
Human associated cyclovirus 8human associated cyclovirus 8hcf2KF031466Complete genomeHuACyV8-hcf2
Human associated cyclovirus 9human associated cyclovirus 9VS5700009KC771281NC_021568Complete genomeHuACyV9-VS5700009
Squirrel associated cyclovirus 1squirrel cyclovirusJP-NUBS-2014LC018134NC_027530Complete genomeSqACyV1-JP-NUBS-2014

Virus names, the choice of exemplar isolates, and virus abbreviations, are not official ICTV designations.
Download GenBank/EMBL query for sequences listed in the table here.

Derivation of names

Cyclo: indicates circle or ring in Greek.

  • Created by
  • When: Jul 6, 2017 10:21 PM
  • Last revision by
  • When: Jul 7, 2017 4:13 AM
  • Revisions: 5
  • Comments: 0