Circoviridae

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Circoviridae
Systematics
Classification : Viruses
Area : Monodnaviria
Empire : Shotokuvirae
Phylum : Cressdnaviricota
Class : Arfiviricetes
Order : Cirlivirales
Family : Circoviridae
Taxonomic characteristics
Genome : (-) ssDNA circular
Baltimore : Group 1
Symmetry : icosahedral
Cover : no
Scientific name
Circoviridae
Left
NCBI  Taxonomy: 39724
ViralZone ( ExPASy , SIB): 11
ICTVdB Virus Code : 00.016

The family Circoviridae (lat. Circulus : circle) comprises two genera and a preliminary genus of viruses with single-stranded, circular DNA with negative or ambisense polarity as genome . The members of the Circoviridae cause diseases in birds ( Circovirus , Gyrovirus ) and pigs ( Circovirus ); the members of the preliminary genus Annelovirus infect various mammals (including humans) as a persistent infection with no detectable disease.

morphology

The non-enveloped capsids of the Circoviridae are (very variable according to species) 15-30 nm in diameter and have an icosahedral symmetry . The capsid usually consists of only one capsid protein (CP) with a molecular mass between 30 (PCV-1/2) and 50  kDa (CAV). So far, there is only evidence of three different capsid proteins in the case of the beak and feather disease virus (BFDV).

The single-stranded DNA genome is of negative polarity ( Gyrovirus , Anellovirus ) or has ambisense polarity ( Circovirus ), which means that opposite reading directions are present on an identical DNA strand. The viral genome is between 1.8 and 2.3 kb in size and codes for 2-4 genes. Circoviridae do not have their own DNA polymerase , but use cellular DNA polymerases as an intermediate step in virus replication to synthesize a double-stranded DNA strand.

Biological importance

Circoviridae have a very narrow host range. Faecal-oral transmission is assumed in the avian species; congenital infection via the egg (vertical transmission) has been demonstrated. The Circoviridae are widespread within a population (95% TTV in humans) and mostly show a high degree of variability and geographically different subtypes or groups.

Veterinary important infections caused by Circoviridae are:

  • the infectious anemia of chickens ( chicken anemia virus , CAV)
  • Psittacine Beak and Feather Disease PBFD ( Beak and feather disease virus , BFDV)
  • Circovirus disease in pigeons (Pigeon Circovirus, PiCV)
  • Postweaning Multisystemic Wasting Syndrome (PMWS) in pigs ( Porcines Circovirus-2 , PCV-2)
  • Porcine Dermatitis and Nephropathy Syndrome (PDNS) in pigs ( Porcine Circovirus-2 , PCV-2)

Systematics
preliminary species within the genus:

not classified within the family:

preliminary species within the genus:

literature

  • CM Fauquet, MA Mayo et al .: Eighth Report of the International Committee on Taxonomy of Viruses , London, San Diego, 2004
  • David M. Knipe, Peter M. Howley, et al. (eds.): Fields' Virology, 4th Edition, Philadelphia 2001

Individual evidence

  1. ↑ a b c d e ICTV: ICTV Taxonomy history: Porcine circovirus 1 , EC 51, Berlin, Germany, July 2019; Email ratification March 2020 (MSL # 35)
  2. ↑ SIB: Circovirus , on: ViralZone
  3. ↑ SIB: Gyrovirus , on: ViralZone

Web links