Bunyavirales

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Bunyavirales
Rift Valley Fever Virus.jpg

Rift Valley Fever Viruses in Tissues

Systematics
Classification : Viruses
Area : Riboviria
Empire : Orthornavirae
Phylum : Negarnaviricota
Subphylum : Polyploviricotina
Class : Ellioviricetes
Order : Bunyavirales
Taxonomic characteristics
Genome : (-) ss RNA segmented
Baltimore : Group 5
Symmetry : helical
Cover : available
Scientific name
Bunyavirales
Left

The bunyaviruses ( order Bunyavirales , formerly family Bunyaviridae ) comprise enveloped viruses with a single-stranded, segmented RNA as a genome . The RNA segments are predominantly of negative polarity , e.g. T. but also ambisense RNA.

The first representatives of the bunyaviruses were isolated in the place Bunyamwera ( Uganda ), from which the name of the order is derived.

morphology

The virions of the bunyaviruses have a round to irregular shape and, depending on the genus, are 80–120 nm in size. Two 5–10 nm long glycoprotein spikes (virus proteins Gn and Gc ) are embedded in the virus envelope . The capsid (a ribonucleocapsid) is 2 to 2.5 nm thick and, depending on the length of the RNA strand, 200-3000 nm long and of helical symmetry .

The viral genome consists of one molecule each of three single-stranded RNAs with negative or mixed (i.e. ambisense, +/-) polarity. They are called L ( large ), M ( medium ) and S ( small ). The ends of the individual RNA segments are complementary, so that they close to form three non-covalently closed rings (with ring-shaped capsids). The sequence of these terminal RNA sections are highly conserved within a genus. By segmenting the genome, a genetic reassortment (reassortment) is possible, similar to the Orthomyxoviridae (e.g. influenza viruses) , which has already been shown for some species in vitro and in vivo .

All bunyaviruses have four structural proteins: the two envelope proteins Gc and Gn (encoded on the M segment), the nucleocapsid protein N (on the S segment) and a large RNA polymerase molecule L (on the L segment). Another 1–2 non-structural proteins (NSm and NSs) of still little researched function are coded on the M or S segment, depending on the genus; the genus Hantavirus has no other non-structural protein.

Biological properties

The bunyaviruses (with the exception of the Fimoviridae family and the Tospovirus genus ) can multiply in vertebrates and, alternatively, in insects . When replicating in vertebrate cells, they dissolve the cell (cytolytically) while no or only slight cytopathological changes are found in insect cells. The individual virus species are very closely adapted to their vertebrate and insect host.

The different virus species are transmitted as vectors by mosquitoes , ticks , sand flies (genus Phlebotomus ) and other insects . No vector of this type is known for the hantaviruses; airborne transmission has been described for them and non-cytopathogenic persistence in rodents as hosts. The genus Tospovirus occupies a special position, as it only infects plants (like the Fimoviridae family ) and is transmitted by fringed winged birds ( Thysanoptera ).

Systematics

Structure of peribunya viruses (left) and TEM image of its member California Encephalitis Virus (CEV, right)

In 2016, the previous family Bunyaviridae was divided by the International Committee on Taxonomy of Viruses (ICTV) into several families ( Hantaviridae , Nairoviridae , Peribunyaviridae , Phenuiviridae , Tospoviridae ) of the newly formed order Bunyavirales , which also includes the Arenaviridae family and other smaller families of the Arenaviruses . The systematics given here represents the status of November 2018 (type species of the families are marked with '(*)'. Viruses (subspecies) belonging to some selected species are listed.

  • Family Peribunyaviridae - most of the species that were formerly part of the Bunyaviridae are summarized here:
  • Genus Emaravirus with 9 species including:
    • Species fig mosaic virus , officially Fig mosaic emaravirus (*)
  • Genus Orthohantavirus , formerly Hantavirus , with 35 species, including:
    • Species Hantaanvirus , officially Hantaan orthohantavirus (*) - natural infections especially in rodents, some of which can also cause hemorrhagic fever in humans
    • Species Sin Nombre Virus , officially Sin Nombre orthohantavirus - natural infections mainly in rodents, some of which can also cause hemorrhagic fever in humans
  • Genus loan virus with 2 species
    • Species Longquan loanvirus (*)
  • Genus Mobatvirus with 3 species
    • Species Nova mobatvirus (*)
  • Genus thottim virus with 2 species
    • Species Thottopalayam thottimvirus (*)
  • Genus Orthophasmavirus with 5 species including:
    • Species Kigluaik phantom virus , officially Kigluaik phantom orthophasmavirus (*)
  • Genus Feravirus (formerly in own family Feraviridae ) with 1 species:
  • Genus Inshuvirus with 1 species
    • Species Insect inshuvirus (*)
  • Genus Jonvirus (formerly own family Jonviridae ) with 1 species, including:
    • Species Jonchet virus , officially Jonchet jonvirus , obsolete Jonchet orthojonvirus (*)
  • Genus Wuhivirus with 1 species
    • Species Insect wuhivirus (*)

In addition, there are the number of virus species that have been proposed for the order Bunyavirales but have not yet been assigned to a genus.

Individual evidence

  1. ICTV Master Species List 2018b v1 MSL # 34, Feb. 2019
  2. a b ICTV: ICTV Taxonomy history: Akabane orthobunyavirus , EC 51, Berlin, Germany, July 2019; Email ratification March 2020 (MSL # 35)
  3. ViralZone: ICTV 2016 Master Species List # 31 with Acronyms, (Excel XLSX) , SIB Swiss Institute of Bioinformatics
  4. SIB: Orthotospovirus , on: ViralZone
  5. SIB: [1] , on: ViralZone
  6. a b Piet Maes et al. : Expansion of the order Bunyavirales , ICTV Technical Report, June 2018, doi: 10.13140 / RG.2.2.25861.40163
  7. a b An alternative proposal was previously: Species ' Tick-borne phlebovirus ' (TBPV) of the genus Phlebovirus ; Shu Shen, Xiaomei Duan, Bo Wang, Liying Zhu, Yanfang Zhang, Jingyuan Zhang, Jun Wang, Tao Luo, Chun Kou, Dan Liu, Chuanwei Lv, Lei Zhang, Chenchen Chang, Zhengyuan Su, Shuang Tang, Jie Qiao, Abulimiti Moming , Cheng Wang, Abulikemu Abudurexiti, Hualin Wang, Zhihong Hu, Yujiang Zhang, Surong Sun, Fei Deng: A novel tick-borne phlebovirus, closely related to severe fever with thrombocytopenia syndrome virus and Heartland virus, is a potential pathogen , in: Nature : Emerging Microbes & Infections, Volume 7, Article No. 95, May 25, 2018, doi : 10.1038 / s41426-018-0093-2

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

Web links