Circovirus

VIRION

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

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 the capsid proteins and form virions released from the cell by budding.

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)

All proteins are shown (view only 23 complete proteome entries)

Capsid protein

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CAPSD_PCV1CPorcine circovirus 1 (isolate China) (PCV1) reference strain
CAPSD_BFDVBeak and feather disease virus (BFDV)
CAPSD_CACVCanary circovirus (CaCV)

Probable capsid protein

CAPSD_GOCVGoose circovirus (GoCV)

Probable capsid protein

CAPSD_PICVPigeon circovirus (PiCV) (Columbid circovirus)

Probable capsid protein

CAPSD_PCV2Porcine circovirus 2 (PCV2)

Protein NS0


NS0_PCV2Porcine circovirus 2 (PCV2)

Uncharacterized protein ORF3

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ORF3_BFDVBeak and feather disease virus (BFDV)
ORF3_PCV2Porcine circovirus 2 (PCV2)

Protein ORF3

Uncharacterized protein ORF4


ORF4_BFDVBeak and feather disease virus (BFDV)

Uncharacterized protein ORF5


ORF5_BFDVBeak and feather disease virus (BFDV)

Uncharacterized protein ORF6


ORF6_BFDVBeak and feather disease virus (BFDV)

Uncharacterized protein ORF7


ORF7_BFDVBeak and feather disease virus (BFDV)

Uncharacterized protein ORFC2

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ORFC2_GOCVGoose circovirus (GoCV)
ORFC2_PICVPigeon circovirus (PiCV) (Columbid circovirus)

Uncharacterized protein ORFC3


ORFC3_PICVPigeon circovirus (PiCV) (Columbid circovirus)

Uncharacterized protein ORFC4


ORFC4_PICVPigeon circovirus (PiCV) (Columbid circovirus)

Uncharacterized protein ORFV2


ORFV2_GOCVGoose circovirus (GoCV)

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

Select_all Deselect_all  
REP_PCV1CPorcine circovirus 1 (isolate China) (PCV1) reference strain
REP_BFDVBeak and feather disease virus (BFDV)
REP_CACVCanary circovirus (CaCV)
REP_GOCVGoose circovirus (GoCV)
REP_PICVPigeon circovirus (PiCV) (Columbid circovirus)
REP_PCV2Porcine circovirus 2 (PCV2)