Circoviridae

The family Circoviridae (Latin circulus: Kreis ) comprises two genera and a provisional genus of viruses with single-stranded, circular DNA with negative or ambisense polarity as genome. The members of the Circoviridae are causative agents of diseases in birds ( circovirus Gyrovirus ) and swine ( circovirus ); the members of the provisional genus Annelovirus infect various mammals (including humans) than persistent infection with no detectable disease.

Morphology

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

The single-stranded DNA genome of negative polarity ( Gyrovirus, Anellovirus ) or having ambisense polarity ( circovirus ), i.e. that opposite directions of reading on an identical DNA strand present. The viral genome is 1.8 to 2.3 kb in size and encodes for 2-4 genes. Circoviridae not have their own DNA polymerase, however, use for the synthesis of a double- strand DNA as an intermediate step in the virus replication, the cellular DNA polymerases.

Biological Significance

Circoviridae have a very narrow host range. In the avian species is a fecal- oral transmission is assumed a congenital infection on the egg ( vertical transmission ) could be detected. Within a population, the Circoviridae are widespread (TTV in humans to 95%) and usually show a high variability and geographically distinct subtypes or groups.

Veterinary Medical significant infections caused by Circoviridae are:

  • Infectious anemia in chickens (chicken anemia virus, CAV)
  • Psittacine Beak and Feather Disease PBFD ( Beak and feather disease virus, BFDV )
  • Circovirus disease of pigeons ( pigeon circovirus, PiCV )
  • Postweaning multisystemic wasting syndrome ( PMWS ) in pigs ( porcine circovirus -2, PCV -2)
  • Porcine dermatitis and nephropathy syndrome ( PDNS ) in pigs ( porcine circovirus -2, PCV -2)

System

  • Genus circovirus Species Beak and feather disease virus ( BFDV )
  • Species goose circovirus ( GoCV )
  • Species pigeon circovirus ( PiCV ), agent of the Young Pigeon Disease Syndrome ( " Young Bird Sickness " )
  • Porcine circovirus species -1 (PCV -1)
  • Porcine circovirus species -2 ( PCV -2)
  • Species duck circovirus ( DuCV )
  • Species Finch circovirus ( FiCV )
  • Species of gulls circovirus ( GuCV )
  • Genus Gyrovirus
  • Species chicken anemia virus (CAV)

Non- classified within the family:

  • Genus Anellovirus
  • Species Torqueno Teno virus ( TTV ) (5 groups / genotypes)
  • Species Torqueno Teno Mini Virus ( TTMV ) (13 TTMV species)
  • Species Dog Torqueno Teno virus ( TTV10 -Cf )
  • Species pork Torqueno Teno virus ( TTV31 SD )
  • Species Tamarin Torqueno Teno virus ( TTV2 -Sun)
  • Species Tupaia - Torqueno Teno virus ( TTV14 - TB )
Virus classification National Center for Biotechnology Information
190919
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