Flavivirus
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Flavivirus | ||||||||||||||||
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The genus Flavivirus comprises enveloped viruses with a positive-stranded RNA single strand as genome , which are transmitted to birds and mammals as vectors by arthropods ( ticks and mosquitoes ) . The name of the genus and the entire virus family Flaviviridae is derived from the yellow fever virus in humans (from Latin flavus , "yellow"), which Walter Reed recognized in 1904 as being transmitted by mosquitoes.
Viruses of the genus Flavivirus cause important diseases in animals and humans. These include diseases that correspond to a viral hemorrhagic fever or are characterized by an infection of the central nervous system in the sense of encephalitis , meningoencephalitis or leukoencephalitis . In addition to yellow fever , these include, for example, early summer meningoencephalitis (TBE), Japanese encephalitis , dengue fever and West Nile fever .
morphology
The virus particles (virions) of the flaviviruses are about 50 nm in diameter and, in the electron microscopic representation, of spherical, irregular shape. Analyzes by means of cryoelectron microscopy showed an icosahedral symmetry of the virus envelope in the dengue virus , which suggests an interaction of the envelope proteins with the capsid proteins. The capsid is made up of only one capsid protein (C, 11 kDa ). 90 dimers of the E protein (50 kDa) are embedded in the virus envelope of the virion. Another, smaller envelope protein ( M protein , 26 kDa) is found between this network of E dimers .
Genome organization
The positive-stranded RNA is about 11,000 nucleotides long and comprises only one open reading frame that codes for a polyprotein . The viral protease (N-terminal part of NS3) and the host's own proteases cut this polyprotein into 3 structural (C, prM, E) and 7 non-structural proteins (NS1, NS2A, NS2B, NS3, NS4A, NS4B, NS5 ); the list corresponds to the arrangement of the genes coding for the proteins on the genome. In contrast to the other genera of the Flaviviridae family , viruses of the Flavivirus genus have a 5 'cap structure of type 1 (m-7GpppAmp) followed by a conserved dinucleotide A G at the 5' end of the RNA . In contrast to the other genera, flaviviruses do not have a poly (A) tail at the 3 'end .
Replication
The viruses attack monocytes , macrophages and dendritic cells, among others . They attach to the cell surface via specific receptors and are taken up by a developing endosome vesicle . Inside the endosome, the acidic pH induces the fusion of the endosome membrane and the virus envelope. This causes the capsid to enter the cytosol , disintegrate, and release the genome. Both receptor binding and membrane fusion are catalyzed by protein E, which undergoes a conformational change at acidic pH, which leads to the 90 homodimers reorganizing into 60 homotrimers.
After entering the host cell, the viral genome is replicated in the rough endoplasmic reticulum and in so-called vesicle packets . Within the ER, an immature form of the virus particles is first produced, in which the M protein has not yet been cleaved by a maturation step and is present as prM ( precursor M ) in a complex with E. The immature particles are processed in the Golgi apparatus by the host protein furin , which cuts prM into M. This releases E from the complex and can take its place in the mature, infectious virion.
transmission
Flaviviruses can be transmitted indirectly by blood-sucking insects or in rare cases (for example with the Rio Bravo virus ) directly from one vertebrate to another. Some flaviviruses circulate between rodents and bats with no other vector known.
Systematics
The viruses of the genus Flavivirus were previously distinguished as arbovirus group B from arbovirus group A because of their transmission by arthropods ; the genus Alphavirus of the Togaviridae family later emerged from the latter .
The genus Flavivirus contains 89 virus species (as of 2018; in 2009 there were 53 species with 73 serotypes). The species are classified into (non-taxonomic) groups according to the type of vector (mosquito, tick), unknown vector (NKV group: no known vector ) and on the basis of phylogenetic studies. The English names are the official species names according to ICTV (International Committee on Taxonomy of Viruses), as of November 2018.
1. Flaviviruses transmitted by ticks
- Group of tick-borne flaviviruses in mammals ( tick-borne encephalitis complex , TBE)
- Species Gadgets Gully Virus ( en.Gadgets Gully virus , GGYV)
- Species Kyasanur Forest Disease Virus ( KFD virus , en. Kyasanur Forest disease virus , KFDV) with subtype Al Khurma virus
- Species Langat virus (en. Langat virus , LGTV)
- Species Louping Ill virus (en. Louping ill virus , LIV)
- Species Omsk hemorrhagic fever virus (en. Omsk hemorrhagic fever virus , OHFV)
- Species Powassan virus (en. Powassan virus , POWV) with subtype Deer tick virus (DTV)
- Species Royal farm virus (s. Royal Farm virus , RFV) with subtype Karshi virus (ksiv)
- Species TBE virus (s. Tick-borne encephalitis virus , TBEV) with subtype Absettarov virus (ABSV)
- Group of tick-borne flaviviruses in seabirds
- Species Kadam virus (en. Kadam virus , KADV)
- Species Meaban virus (en. Meaban virus , MEAV)
- Species Saumarez Reef Virus (en. Saumarez Reef virus , SREV)
- Species Tyuleniy virus ( en.Tyuleniy virus , TYUV)
2. Flaviviruses transmitted by mosquitoes ( Mosquito Borne Encephalitis Complex , MBE)
- Aroa virus group
- Species Aroa virus ( en.Aroa virus , AROAV) with subtypes Bussuquara virus (BSQV), Iguape virus (IGUV), Naranjal virus (NJLV)
- Dengue virus group
- Species dengue virus ( dengue virus , DENV)
- Species Kedougou virus (en. Kedougou virus , KEDV)
- Japanese encephalitis virus group
- Species Cacipacore virus (en. Cacipacore virus , CPCV)
- Species Japanese encephalitis virus (s. Japanese encephalitis virus , JEV), subtypes JAOARS982, M28, Nakayama, SA (V), and SA-14
- Species Koutango virus (en. Koutango virus , KOUV)
- Species Murray Valley encephalitis virus ( en.Murray Valley encephalitis virus , MVEV)
- Species St. Louis encephalitis virus (en. St. Louis encephalitis virus , SLEV) - St. Louis encephalitis
- Species Usutu virus (en. Usutu virus , USUV)
- Species West Nile virus (en. West Nile virus , WNV) with subtype Kunjin virus
- Species Yaounde virus ( en.Yaounde virus , YAOV)
- Kokobera virus group
- Species Kokobera virus (en. Kokobera virus , KOKV) with subtypes New Mapoon virus (NMV) and Stratford virus (STRV)
- Ntaya virus group
- Species Bagaza virus ( en.Bagaza virus , BAGV)
- Species Ilheus virus (en. Ilheus virus , ILHV) with subtype Rocio virus (ROCV): Rocio viral encephalitis
- Species Israel turkey meningoencephalitis virus ( en.Israel turkey meningoencephalomyelitis virus , ITV)
- Species Ntaya virus ( en.Ntaya virus , NTAV)
- Species " T'Ho virus ", not confirmed by ICTV
- Species Tembusu virus ( en.Tembusu virus , TMUV) with subtypes Duck egg drop syndrome virus (DEDSV, BYDV) and Sitiawan virus (STWV)
- Spondweni virus group
- Species " Spondweni virus " (en " Spondweni virus ", SPONV), not confirmed by ICTV
- Species Zika virus ( en.Zika virus , ZIKV)
- Yellow fever virus group
- Species Banzi virus (en. Banzi virus , BANV)
- Species Bouboui virus ( en.Bouboui virus , BOUV)
- Species Edge Hill virus (s. Edge Hill virus , EHV)
- Species " Bamaga virus " (en. " Bamage virus ", BgV), not confirmed by ICTV
- Species " Fitzroy river virus ", not confirmed by ICTV
- Species Jugra virus ( en.Jugra virus , JUGV)
- Species Saboya virus (en. Saboya virus , SABV)
- Species Sepik virus ( en.Sepik virus , SEPV)
- Species Uganda S virus (en. Uganda S virus , UGSV)
- Species Wesselsbron virus (en. Wesselsbron virus , WESSV)
- Species yellow fever virus (s. Yellow fever virus , YFV)
3. Flaviviruses with unknown vector
- Species Entebbe bat virus (s. Entebbe bat virus , ENTV)
- Species Yokose virus ( en.Yokose virus , YOKV)
- Species " Nanay virus "
- Species " Tamana bat virus " (en. " Tamana bat virus " TABV), not confirmed by ICTV
- Modoc virus group
- Species Apoi virus (en. Apoi virus , APOIV)
- Species Cowbone Ridge Virus ( en.Cowbone Ridge virus , CRV)
- Species Jutiapa virus (en. Jutiapa virus , JUTV)
- Species Modoc virus ( Modoc virus , MODV)
- Species Sal Vieja virus ( en.Sal Vieja virus , SVV)
- Species San Perlita virus ( en.San Perlita virus , SPV)
- Rio Bravo Virus Group
- Species Bukalasa bat virus ( en.Bukalasa bat virus , BBV)
- Species Carey Island virus (en. Carey Island virus , CIV)
- Species Dakar bat virus ( en.Dakar bat virus , DBV)
- Species Montana myotis leukoencephalitis virus (en. Montana myotis leukoencephalitis virus , MMLV)
- Species Phnom Penh bat virus (en. Phnom Penh bat virus , PPBV) with subspecies Batu cave virus
- Species Rio Bravo virus ( en.Rio Bravo virus , RBV)
4. Non-vertebrate virus group ( English Non vertebrate viruses )
- Species “ Soybean cyst nematode virus 5 ”, not confirmed by ICTV
5. Other unclassified candidates for this genus
- Species " Mediterranean Ochlerotatus flavivirus "
- Species " Nanay virus "
- Species " Nounané virus "
- Species " Ochlerotatus caspius flavivirus "
- Species " Palm Creek virus "
- Species " Parramatta River virus "
- Species " Aedes flavivirus - NCBI unclassif Flavivirus "
- Species " Culex theileri flavivirus "
literature
- H.-J. Thiel, MS Collett, et al. : Genus Flavivirus . In: CM Fauquet, MA Mayo et al. : Eighth Report of the International Committee on Taxonomy of Viruses . London / San Diego, 2005, ISBN 0-12-249951-4
- D. Gubler, G. Kuno, L. Markoff: Flaviviruses . In: David M. Knipe, Peter M. Howley (eds.-in-chief): Fields' Virology . 5th edition. Philadelphia 2007, Volume 1, ISBN 0-7817-6060-7 , pp. 1153 ff.
- EA Gould, T. Solomon: Pathogenic flaviviruses . Seminar. In: Lancet 2008, 371, pp. 500-509
Web links
- Genus Flavivirus in the NCBI database
- Genus Flavivirus in the ICTV database
Individual evidence
- ↑ ICTV Master Species List 2018b.v2 . MSL # 34, March 2019
- ↑ a b c d ICTV: ICTV Taxonomy history: Yellow fever virus , EC 51, Berlin, Germany, July 2019; Email ratification March 2020 (MSL # 35)
- ^ EA Gould, T Solomon: Pathogenic flaviviruses . In: The Lancet . 371, No. 9611, February 2008, pp. 500-9. doi : 10.1016 / S0140-6736 (08) 60238-X . PMID 18262042 .
- ↑ RJ Kuhn, W Zhang, MG Rossmann et al .: Structure of dengue virus: implications for flavivirus organization, maturation, and fusion . In: Cell . 108, No. 5, March 2002, pp. 717-25. PMID 11893341 .
- ↑ a b c d A Sampath, R Padmanabhan: Molecular targets for flavivirus drug discovery . In: Antiviral Research . 81, No. 1, January 2009, pp. 6-15. doi : 10.1016 / j.antiviral.2008.08.004 . PMID 18796313 .
- ↑ Master Species List (# 33) 2018a v1. ICTV , autumn 2018
- ↑ H. Weissenböck, Z. Hubálek, T. Bakonyi, N. Nowotny: Zoonotic mosquito-borne flaviviruses: worldwide presence of agents with proven pathogenicity and potential candidates of future emerging diseases . In: Veterinary Microbiology, Elsevier, 2010, 140 (3-4), pp. 271 ff, doi: 0.1016 / j.vetmic.2009.08.025
- ^ NCBI: Tick-borne encephalitis virus group
- ^ Anne Piantadosi, Daniel B Rubin, Daniel P McQuillen, Liangge Hsu, Philip A Lederer: Emerging Cases of Powassan Virus Encephalitis in New England: Clinical Presentation, Imaging, and Review of the Literature . In: Clinical Infectious Diseases: An Official Publication of the Infectious Diseases Society of America . tape 62 , no. 6 , March 15, 2016, ISSN 1537-6591 , p. 707-713 , doi : 10.1093 / cid / civ1005 , PMID 26668338 , PMC 4850925 (free full text).
- Jump up ↑ Powassan Basics: About Powassan Virus Disease , Minnesota Department of Health, April 11, 2019
- ^ NCBI: Karshi virus
- ^ NCBI: Seaborne tick-borne virus group
- ^ NCBI: Dengue virus group
- ↑ NCBI: Japanese encephalitis virus group
- ↑ NCBI: Kokobera virus group
- ↑ NCBI: Ntaya virus group
- ↑ Joel H. Ellwanger et al. : Rocio Virus: An Overview , on: ResearchGate, July 2017
- ↑ NCBI: T'Ho virus (species)
- ↑ PMC 5469153 (free full text)
- ↑ Peipei Liu et al : Genomic and antigenic characterization of the newly emerging Chinese duck egg-drop syndrome flavivirus: genomic comparison with Tembusu and Sitiawan viruses , in: Journal of General Virology, Volume 93, No. 10, October 1, 2012, doi : 10.1099 / vir.0.043554-0
- ^ NCBI: Yellow fever virus group
- ^ Andrew F. van den Hurk, Willy W. Suen, Roy A. Hall, Caitlin A. O'Brien, Helle Bielefeldt-Ohmann, Jody Hobson-Peters, Agathe MG Colmant: A newly discovered flavivirus in the yellow fever virus group displays restricted replication in vertebrates . In: Journal of General Virology . 97, No. 5, 2016, pp. 1087-1093. doi : 10.1099 / jgv.0.000430 . PMID 26878841 . PDF
- ↑ NCBI: Fitzroy river virus (species)
- ↑ Cheryl A. Johansen et al : Characterization of Fitzroy River Virus and Serologic Evidence of Human and Animal Infection , in: Emerging Infectious Diseases, Volume 23, No. 8, August 2017
- ↑ NCBI: Nanay virus (species)
- ^ NCBI: Modoc virus group
- ↑ S Bekal, LL Domier, B Gonfa, NK McCoppin, KN Lambert, K Bhalerao: A novel flavivirus in the soybean cyst nematode . In: Journal of General Virology . 95, No. Pt 6, 2014, pp. 1272-1280. doi : 10.1099 / vir.0.060889-0 . PMID 24643877 .
- ^ NCBI: unclassified flavivirus