Circoviridae
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Circoviridae | ||||||||||||||
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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
- Genus circovirus
- Species Beak and feather disease virus (BFDV)
- Species canary circovirus (CaCV)
- Species goose circovirus (GoCV)
- Species pigeon circovirus (PiCV), pathogen of the Young Pigeon Disease Syndrome ("young pigeon disease ")
- Species Porcine Circovirus-1 (PCV-1)
- Species Porcine Circovirus-2 (PCV-2)
- preliminary species within the genus:
- Species duck circovirus (DuCV)
- Species finch circovirus (FiCV)
- Species seagull circovirus (GuCV)
- Genus Gyrovirus
- Species Chicken Anemia Virus (CAV)
not classified within the family:
- Genus Anellovirus
- Species Torqueno Teno Virus (TTV) (5 groups / genotypes)
- preliminary species within the genus:
- Species Torqueno Teno Mini Virus (TTMV) (13 TTMV species)
- Species feline torqueno teno virus (TTV4-Fc)
- Species canine torqueno teno virus (TTV10-Cf)
- Species owl monkey torqueno teno virus (TTV3-At)
- Species porcine torqueno teno virus (TTV31-Sd)
- Species Tamarin Torqueno Teno Virus (TTV2-So)
- Species Tupaia Torqueno Teno Virus (TTV14-Tbc)
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
- ↑ a b c d e ICTV: ICTV Taxonomy history: Porcine circovirus 1 , EC 51, Berlin, Germany, July 2019; Email ratification March 2020 (MSL # 35)
- ↑ SIB: Circovirus , on: ViralZone
- ↑ SIB: Gyrovirus , on: ViralZone