Circovirus

VIRION

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

GENOME

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.

GENE EXPRESSION

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.

REPLICATION

NUCLEAR

  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.

Host-virus interaction

Autophagy modulation

Cap protein of PCV2 induces activation of host autophagy in order to enhance its own replication .

Apoptosis modulation

PCV2 ORF3-encoded protein induces apoptosis by activating caspase-8 and caspase-3 pathways . This protein may be a candidate for PML bodies inhibition which is essential for nuclear virus replication in mammals.

Matching UniProtKB/Swiss-Prot entries

24 entries grouped by protein (browse by keywords)

6 entries

Capsid protein

Select_allDeselect_all
CAPSD_BFDV
Beak and feather disease virus (BFDV) reference strain
CAPSD_CACV
Canary circovirus (CaCV) reference strain

Probable capsid protein

CAPSD_PCV1C
Porcine circovirus 1 (isolate China) (PCV1) reference strain
CAPSD_GOCV
Goose circovirus (GoCV)

Probable capsid protein

CAPSD_PCV2
Porcine circovirus 2 (PCV2)
CAPSD_PICV
Pigeon circovirus (PiCV) (Columbid circovirus)

Probable capsid protein

1 entry

Protein NS0

NS0_PCV2
Porcine circovirus 2 (PCV2)

2 entries

Protein ORF3

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ORF3_BFDV
Beak and feather disease virus (BFDV) reference strain

Uncharacterized protein ORF3

ORF3_PCV2
Porcine circovirus 2 (PCV2)

1 entry

Uncharacterized protein ORF4

ORF4_BFDV
Beak and feather disease virus (BFDV) reference strain

1 entry

Uncharacterized protein ORF5

ORF5_BFDV
Beak and feather disease virus (BFDV) reference strain

1 entry

Uncharacterized protein ORF6

ORF6_BFDV
Beak and feather disease virus (BFDV) reference strain

1 entry

Uncharacterized protein ORF7

ORF7_BFDV
Beak and feather disease virus (BFDV) reference strain

2 entries

Uncharacterized protein ORFC2

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ORFC2_GOCV
Goose circovirus (GoCV)
ORFC2_PICV
Pigeon circovirus (PiCV) (Columbid circovirus)

1 entry

Uncharacterized protein ORFC3

ORFC3_PICV
Pigeon circovirus (PiCV) (Columbid circovirus)

1 entry

Uncharacterized protein ORFC4

ORFC4_PICV
Pigeon circovirus (PiCV) (Columbid circovirus)

1 entry

Uncharacterized protein ORFV2

ORFV2_GOCV
Goose circovirus (GoCV)

6 entries

Replication-associated protein (EC 2.7.7.-) (EC 3.1.21.-) (EC 3.6.1.3) (ATP-dependent helicase Rep) (RepP)

Select_allDeselect_all
REP_BFDV
Beak and feather disease virus (BFDV) reference strain
REP_CACV
Canary circovirus (CaCV) reference strain
REP_PCV1C
Porcine circovirus 1 (isolate China) (PCV1) reference strain
REP_GOCV
Goose circovirus (GoCV)
REP_PCV2
Porcine circovirus 2 (PCV2)
REP_PICV
Pigeon circovirus (PiCV) (Columbid circovirus)