Cyclovirus (taxid:742914)



Non-enveloped, round, T=1 icosahedral symmetry, about 17 nm in diameter. The capsid consists of 12 pentagonal trumpet-shaped pentamers.



Monopartite, circular, ssDNA genome of about 1800 to 2000bp.
The genome is replicated through double-stranded intermediates. The replication (Rep) protein initiates and terminates rolling circle replication, the host DNA polymerase being used for DNA replication itself. There is a potential stem-loop structure in the intergenic region that includes a conserved nonanucleotide sequence (AGTATTAC) where ssDNA synthesis is initiated.


The encapsidated viral DNA and the complementary DNA of the replicative intermediate encode two mRNAs for the Rep and capsid proteins.
Rep mRNA can undergo alternative splicing in some strains to produce Rep' protein.




  1. Virus penetrates into the host cell probably by clathrin- and caveolae-independent endocytosis.
  2. Uncoating, the viral ssDNA genome penetrates into the nucleus.
  3. Viral ssDNA is converted into dsDNA with the participation of cellular factors. dsDNA transcription gives rise to viral mRNAs.
  4. Viral mRNAs are translated to produce viral proteins.
  5. Replication may be mediated by a Rep protein, and would occur by rolling circle producing ssDNA genomes.
  6. These newly synthesized ssDNA can either
    a) be converted to dsDNA and serve as a template for transcription/replication
    b) be encapsidated by capsid protein and form virions released by cell lysis.

Matching UniProtKB/Swiss-Prot entries

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2 entries grouped by protein

1 entry

Capsid protein

Human associated cyclovirus 1 (isolate Homo sapiens/Pakistan/PK5510/2007) (HuCyV-1) (Cyclovirus PK5510) reference strain

1 entry

Replication-associated protein (Rep) (EC 2.7.7.-) (EC 3.1.21.-) (EC 3.6.1.-) (ATP-dependent helicase Rep) (RepP)

Human associated cyclovirus 1 (isolate Homo sapiens/Pakistan/PK5510/2007) (HuCyV-1) (Cyclovirus PK5510) reference strain
These structures were created with the help of Colabfold by Jason Nomburg, Nathan Price and Jennifer Doudna (ModelArchive).

Bat circovirus POA/2012/VI taxid:1572239

Protein ModelArchive
Capsid ma-jd-viral-27483
Replicase ma-jd-viral-17138

Cyclovirus NGchicken15/NGA/2009 taxid:942037

Protein ModelArchive
Cap protein ma-jd-viral-27174
Replication-associated protein (ATP-dependent helicase Rep) (RepP) ma-jd-viral-20740

Cyclovirus PKgoat11/PAK/2009 taxid:942034

Protein ModelArchive
Cap protein ma-jd-viral-27181
Replication-associated protein (ATP-dependent helicase Rep) (RepP) ma-jd-viral-20828

Cyclovirus PKgoat21/PAK/2009 taxid:942033

Protein ModelArchive
Cap protein ma-jd-viral-27171
Replication-associated protein (ATP-dependent helicase Rep) (RepP) ma-jd-viral-20716

Cyclovirus TsCyV-1_JP-NUBS-2014 taxid:1592764

Protein ModelArchive
Capsid protein ma-jd-viral-27192
Replication-associated protein (ATP-dependent helicase Rep) (RepP) ma-jd-viral-20807

Cyclovirus ZM36a taxid:1506568

Protein ModelArchive
Capsid protein ma-jd-viral-27187
Replication-associated protein (ATP-dependent helicase Rep) (RepP) ma-jd-viral-20672

Cyclovirus bat/USA/2009 taxid:942035

Protein ModelArchive
Cap protein ma-jd-viral-27184
Replication-associated protein (ATP-dependent helicase Rep) (RepP) ma-jd-viral-20851

Dragonfly associated cyclovirus 1 taxid:1234879

Protein ModelArchive
Capsid protein ma-jd-viral-27188
Replication-associated protein (ATP-dependent helicase Rep) (RepP) ma-jd-viral-20940

Dragonfly associated cyclovirus 3 taxid:1234881

Protein ModelArchive
Putative capsid protein ma-jd-viral-27170
Replication-associated protein ma-jd-viral-20785
Spliced replication-associated protein ma-jd-viral-20936

Dragonfly associated cyclovirus 5 taxid:1234883

Protein ModelArchive
Putative capsid protein ma-jd-viral-27165
Replication-associated protein (ATP-dependent helicase Rep) (RepP) ma-jd-viral-20817

Dragonfly cyclovirus 2 taxid:1234880

Protein ModelArchive
Putative capsid protein ma-jd-viral-28875
Replication-associated protein (ATP-dependent helicase Rep) (RepP) ma-jd-viral-20804

Feline cyclovirus taxid:1530454

Protein ModelArchive
Capsid protein ma-jd-viral-28014
Replication-associated protein ma-jd-viral-20853

Human cyclovirus taxid:1455626

Protein ModelArchive
Capsid protein ma-jd-viral-28874
Replication-associated protein (ATP-dependent helicase Rep) (RepP) ma-jd-viral-20835

Human cyclovirus VS5700009 taxid:1345637

Protein ModelArchive
Capsid protein ma-jd-viral-27190
Replication-associated protein (ATP-dependent helicase Rep) (RepP) ma-jd-viral-20890

Indian encephalitis associated cyclovirus taxid:1755290

Protein ModelArchive
Capsid protein ma-jd-viral-27182
Replication-associated protein ma-jd-viral-20704