Papillomaviridae

from Wikipedia, the free encyclopedia
Papillomaviridae
Papilloma Virus (HPV) EM.jpg

Human papillomavirus ( TEM picture)

Systematics
Classification : Viruses
Area : Monodnaviria
Empire : Shotokuvirae
Phylum : Cossaviricota
Class : Papovaviricetes
Order : Zurhausenvirales
Family : Papillomaviridae
Taxonomic characteristics
Genome : dsDNA circular
Baltimore : Group 1
Symmetry : icosahedral
Cover : no
Scientific name
Papillomaviridae
Left
NCBI  Taxonomy: 151340
ViralZone ( ExPASy , SIB): 5
ICTVdB Virus Code : 00.099

The virus family Papillomaviridae comprises 16 genera of non-enveloped viruses with a double-stranded, circular DNA as genome . Until 2002, the family Papillomaviridae formed the genus Papillomavirus together with the now own family Polyomaviridae, the family Papovaviridae . In 1964, Joseph Melnick proposed this virus family, which is now obsolete, because of the morphological and genetic similarities. However, the reproduction strategy, the spectrum of diseases and the arrangement of the genes are so different that they have been divided into two different families. In March 2020, has International Committee on Taxonomy of Viruses (ICV) , this former family Papovaviridae again as a class Papovaviricetes introduced to the official taxonomy, under which the two sub-families are reunited.

Papilloma viruses cause skin growths in the form of warts (papillomas) in a large number of different vertebrates . The first agent from this group recognized as a virus was isolated by Richard Shope in 1932 from diseased rabbits ( Shope's rabbit papilloma virus ). The emergence of malignant tumors from these benign growths was already observed at that time. Today, the development of various types of cancer in humans and animals is associated with representatives of the Papillomaviridae . In humans this is predominantly cervical carcinoma due to infections with human papilloma viruses . The reproduction of papillomaviruses is strictly limited to epithelia and they need cells that are in a phase of dedifferentiation to reproduce. Due to this strict tissue tropism , a complete reproduction of the Papillomaviridae in cell cultures has not yet been possible.

In 2013, hybrids between papillomaviruses and polyomaviruses were described .

morphology

Cryo reconstruction of the bovine papillomavirus 1 . The five-pointed symmetry of the subunits can be seen.

The approximately 55 nm large, non-enveloped virions (virus particles) of the papilloma viruses consist of an icosahedral capsid ( T = 7 ), which is made up of 72 capsomeres . Of the capsomeres, 60 are arranged in a five-pointed symmetry ( pentamers ) and these in turn are arranged in 12 six -pointed symmetry ( hexamers ). Disulfide bridges exist between the pentamers . Filamentous capsids can also be observed in the event of incorrect maturation and assembly. The capsomeres are made up of two structural proteins (L1 and L2). The L1 (55 to 60  kDa ) is dominant with over 80% weight. It has outward-facing, species-specific epitopes . The L2 (50 to 53 kDa) has group-specific epitopes. The virions have a high level of environmental stability ; mild detergents (soap), acidic pH values and for virus inactivation fat-dissolving substances commonly used (for example, 2-propanol not) inactivate papilloma viruses. They are heat-stable for 1 hour at 50 ° C.

Inside the capsids is the circular DNA of the virus genome. This is twisted several times ( “supercoiled” ) and, together with cellular histones, forms a nucleoprotein complex that is structurally very similar to eukaryotic nucleosomes . Of the five known histones, the histones H2a , H2b , H3 and H4 are found .

Genome organization

The genome of the papilloma virus is about 6800 to 8400 bp in size and codes with 9 to 10 open reading frames (ORF) for the early virus proteins ( early : E1-E8) and the late structural proteins ( late : L1 and L2). Some species are missing E3 or E8 reading frames. In contrast to the Polyomaviridae , the reading direction is the same for all ORFs. In front of the genes for the early virus proteins there is a regulatory region (LCR, long control region ) which contain control sequences ( promoters , enhancers and origin of replication ). The reading frames partially overlap and are in different reading frames . The viral mRNAs transcribed in the cell nucleus by cellular RNA polymerases are subject to further modifications such as capping , polyadenylation and RNA splicing . The viruses do not have their own DNA polymerase to replicate the genomic DNA of the Papillomaviridae . For virus replication, they rely on sufficient quantities of cellular DNA polymerases to be available and active. Since this is particularly the case during cell division , the Papillomaviridae have developed various mechanisms to stimulate the host cell to divide continuously, through E6 and E7 . These mechanisms are the cause of the typical tissue growths in infections with papilloma viruses and possible degeneration of the cells.

Systematics

The internal systematics of the Papillomaviridae is as follows according to the ICTV , as of November 2018; Genera with no species listed have only one (i.e., they are monotypic):

  • Family Papillomaviridae
  • Subfamily Firstpapillomavirinae
  • Species Alphapapillomavirus 1 to 14
  • Species betapapillomavirus 1 to 6
  • Species gammapapillomavirus 1 to 27
  • Species delta papillomavirus 1 to 7
  • Species epsilon papillomavirus 1 and 2
  • Species Iotapapillomavirus 1 and 2
  • Species Kappapapillomavirus 1 and 2
  • Species lambda papillomavirus 1 to 5
  • Species Mupapillomavirus 1 to 3
  • Species Xipapillomavirus 1 to 5
  • Species Pipapillomavirus 1 and 2
  • Species Rhopapillomavirus 1 and 2
  • Species Taupapillomavirus 1 to 4
  • Species upsilon papillomavirus 1 to 3
  • Species Psipapillomavirus 1 to 3
  • Species Dyoiotapapillomavirus 1 and 2
  • Species Dyokappapapillomavirus 1 to 5
  • Subfamily Secondpapillomavirinae
  • unclassified species within the family Papillomaviridae :

This naming scheme has not changed significantly until April 2020 (ICTV MSL # 35), but there is now a proposal to the ITV for renaming.

swell

  • E.-M. de Villiers, et al. : Family Papillomaviridae . In: CM Fauquet, MA Mayo et al. : Eighth Report of the International Committee on Taxonomy of Viruses . London, San Diego, 2005 pp. 239ff, ISBN 0-12-249951-4
  • Peter M. Howley , Douglas R. Lowy: Papillomaviruses . In: David M. Knipe, Peter M. Howley (eds.-in-chief): Fields' Virology . 5th edition, Volume 2, Philadelphia 2007, pp. 2299ff, ISBN 0-7817-6060-7

Individual evidence

  1. ↑ a b c d e ICTV: ICTV Taxonomy history: Alphapapillomavirus 1 , EC 51, Berlin, Germany, July 2019; Email ratification March 2020 (MSL # 35)
  2. ↑ ICTV: ICTV Taxonomy history: Alphapapillomavirus 1 , EC 51, Berlin, Germany, July 2019; Email ratification March 2020 (MSL # 35)
  3. ↑ Annabel Rector, Marc Van Ranst: Animal papillomaviruses , Virology Volume 445, Edition 1–2, October 2013, pp. 213–223, doi: 10.1016 / j.virol.2013.05.007
  4. ↑ TS Baker et al. : Structures of bovine and human papillomaviruses. Analysis by cryoelectron microscopy and three-dimensional image reconstruction . Biophys. J. (1991) 60 (6): pp. 1445-1456, PMID 1663794 , PMC 1260204 (free full text)
  5. ^ Y. Modis et al. : Atomic model of the papillomavirus capsid . EMBO Journal (2002) 21 (18): pp. 4754–4762, PMID 12234916 , PMC 126290 (free full text)
  6. ↑ ICTV : Master Species List 2018a v1 , MSL including all taxa updates since the 2017 release. Fall 2018 (MSL # 33)
  7. ↑ SIB: Deltapapillomavirus , on: ViralZone
  8. ↑ SIB: Epsilonpapillomavirus , on: ViralZone
  9. ↑ SIB: Zetapapillomavirus , on: ViralZone
  10. ↑ SIB: Etapapillomavirus , on: ViralZone
  11. ↑ SIB: Thetapapillomavirus , on: ViralZone
  12. ↑ SIB: Iotapapillomavirus , on: ViralZone
  13. ↑ SIB: Kappapapillomavirus , on: ViralZone
  14. ↑ SIB: Lambdapapillomavirus , on: ViralZone
  15. ↑ SIB: Mupapillomavirus , on: ViralZone
  16. ↑ SIB: Nupapillomavirus , on: ViralZone
  17. ↑ SIB: Rhopapillomavirus , on: ViralZone
  18. ↑ SIB: Sigmapillomavirus , on: ViralZone
  19. ↑ SIB: Taupapillomavirus , on: ViralZone
  20. ↑ SIB: Upsilonpapillomavirus , on: ViralZone
  21. ↑ SIB: Phipapillomavirus , on: ViralZone
  22. ↑ SIB: Chipapillomavirus , on: ViralZone
  23. ↑ SIB: Psipapillomavirus , on: ViralZone
  24. ↑ SIB: Omegapapillomavirus , on: ViralZone
  25. ↑ SIB: Alefpapillomavirus , on: ViralZone
  26. ↑ Koenraad Van Doorslaer; Peter J. Walker (Ed.): 2019.009D.v1.Papillomaviridae

Web links