| Orthonairovirus
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| Virus classification
|
| (unranked):
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Virus
|
| Realm:
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Riboviria
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| Phylum:
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Negarnaviricota
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| Class:
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Ellioviricetes
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| Order:
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Bunyavirales
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| Family:
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Nairoviridae
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| Genus:
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Orthonairovirus
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| Type species
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Dugbe orthonairovirus
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| Species[1]
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- Artashat orthonairovirus
- Chim orthonairovirus
- Crimean-Congo hemorrhagic fever orthonairovirus
- Dera Ghazi Khan orthonairovirus
- Dugbe orthonairovirus
- Hazara orthonairovirus
- Hughes orthonairovirus
- Kasokero orthonairovirus
- Keterah orthonairovirus
- Nairobi sheep disease orthonairovirus
- Qalyub orthonairovirus
- Sakhalin orthonairovirus
- Tamdy orthonairovirus
- Thiafora orthonairovirus
|
Orthonairovirus is a genus in the family Nairoviridae of the order Bunyavirales that include viruses with circular, negative-sense single stranded RNA. It got its name from the Nairobi sheep disease that affects the gastrointestinal tracts of sheep and goats.[2] The vast majority, and perhaps all viruses in this genus are tick-borne viruses that can have human or other vertebrate hosts.[3]
Taxonomy
Nairobi sheep disease orthonairovirus (NSD) is the prototype virus of the genus.[3][4]
NSD is found in East and Central Africa, and causes acute hemorrhagic gastroenteritis in sheep and goats.
Serogroups
The genus is divided into at least nine serogroups. The Hughes and Sakhalin serogroups appear to be sister groups.
Serogroups
- Crimean-Congo hemorrhagic fever
- Dera Ghazi Khan
- Hughes
- Kasokero
- Nairobi sheep disease
- Qalyub
- Sakhalin
- Tamdy
- Thiafora
Within each serogroup are a number of related viruses:
Crimean-Congo hemorrhagic fever serogroup
- Crimean-Congo hemorrhagic fever virus
- Hazara virus
- Tofla virus
Dera Ghazi Khan serogroup
- Abu Hammad virus
- Abu Mina virus
Hughes serogroup:
- Caspiy virus
- Farallon virus
- Hughes virus
- Puffin Island virus
- Punte Salinas virus
- Raza virus
- Soldado virus
- Zirqa virus
Kasokero serogroup
- Kasokero virus
- Leopards Hill virus
- Yogue virus
Nairobi sheep disease serogroup
- Dugbe virus
- Ganjam virus
- Kupe virus
- Nairobi sheep disease virus
Qalyub serogroup
- Bandia virus
- Chim virus
- Geran virus
- Qalyub virus
Sakhalin serogroup
- Avalon virus
- Paramushir virus
- Sakhalin virus
- Tillamook virus
Tamdy serogroup
- Burana virus
- Tamdy virus
Thiafora serogroup
- Erve virus
- Thiafora virus
Unclassified
- Ahun virus
- Artashat virus
- Burana virus
- Gossas virus
- Issyk-Kul virus
- Keterah virus
- South Bay virus
- Tamdy virus
- Uzun Agach virus
Genome
Nairovirus genomes are negative sense, single-stranded RNA. The complete genome is about 17,100–22,800 nucleotides long, and is divided into three segments: large, medium, and small.[3] The large segment is about 11000–14400 nucleotides long (11–14.4 kb), and it encodes the viral polymerase.[5][6] The medium segment is about 4,400–6,300 nucleotides long (4.4–6.3 kb), and it encodes for glycoproteins G¬n and Gc.[5][6] The small segment is about 1,700–2,100 nucleotides long (1.7–2.1 kb), and it encodes the nucleocapsid protein.[3][5][6]
The genome has terminally redundant sequences, with the sequences being repeated at both ends. The terminal nucleotides are base-paired forming, non-covalently closed, circular RNA.[5] Both the 5’ and 3’ ends have conserved regions, 9 nucleotides in length. The sequences are, 5’end: UCUCAAAGA, and 3’end: AGAGUUUCU.[5]
Virion
The virions for viruses in this genus have a spherical shape.[6] They range in size from about 80–120 nm in diameter, with 50% of their weight attributed to proteins and 20–30% of their weight attributed to lipids.[5] The ribonucleocapsid is filamentous, having a length of about 200-300 nm and a width of about 2–2.5 nm.[5]
These nucleocapsids are surrounded by a single envelope that has projections made of glycoproteins protruding from its surface. These projections evenly cover the surface of the virion, and are about 5–10 nm long.[5] They aid in attachment to the host receptor in replication.
Replication
Nairoviruses attach to the host receptor by their Gn-Gc glycoprotein dimer.[6] The virus is then endocytosed into the host cell via a vesicle. The ribonucleocapsid segments are released into the cytoplasm, commencing transcription.[6] Transcription and replication occur within the cell, and the newly synthesized virions are released by budding.
Transmission & Distribution
Members of this viral genus infect many different vertebrate hosts, and are transmitted via ticks.[5]
Members of the genus Nairovirus may be found the world over, wherever their arthropod vectors and vertebrate hosts are found together.[6]
Evolution
Phylogenetic analysis has shown that these viruses fall into two major monophyletic groups, the hard (Ixodidae) and soft (Argasidae) tick-vectored groups.[7] Fossil and phylogenetic data places the hard tick-soft tick divergence between 120 million years ago and 92 million years ago. This suggests that the Nairoviruses have been associated with these ticks for over 100 million years.
Additionally, nairoviruses vectored by ticks of the genera Argas, Carios and Ornithodoros form three separate monophyletic lineages, again supporting the suggestion of host-virus cospeciation.
The hard bodied tick serogroups are
- Crimean-Congo hemorrhagic fever
- Nairobi sheep disease
- Sakhalin
- Tamdy
The soft bodied tick serogroups are
- Hughes
- Dera Ghazi Khan
- Qalyub
The tick vectors for the Kasokero and Thiafora serogroups are not currently known.
Clinical importance
Only four viruses in this genus have, to date, been recognised as human pathogens:
- Crimean-Congo hemorrhagic fever virus
- Dugbe virus
- Nairobi sheep disease virus
- Kasokero virus.
A fifth— Erve virus —may also be pathogenic for humans.
Notes and references
- ^ Virus Taxonomy: 2018 Release, EC 50, Washington, DC, July 2018, Email ratification October 2018 (MSL #33) https://talk.ictvonline.org/taxonomy/
- ^ "ICTV 9th Report (2011) Bunyaviridae" (html). International Committee on Taxonomy of Viruses (ICTV). Retrieved 31 January 2019.
Nairo: from Nairobi sheep disease, first reported disease caused by member virus.
- ^ a b c d Crabtree, Mary B., Rosemary Sang, and Barry R. Miller. "Kupe Virus, a New Virus in the Family Bunyaviridae, Genus Nairovirus, Kenya." Emerging Infectious Diseases 15 (2009): 147–54.
- ^ Clerx, John PM, Jordi Casals, and David HL Bishop. "Structural Characteristics of Nairoviruses (Genus Nairovirus, Bunyaviridae)." Journal of General Virology 55 (1981): 165–78.
- ^ a b c d e f g h i Büchen-Osmond, Cornelia. "00.011.0.03. Nairovirus." ICTVdb Virus Descriptions. 25 Apr. 2006. International Committee on Taxonomy of Viruses. 17 Apr. 2009 <http://phene.cpmc.columbia.edu/ICTVdB/00.011.0.03.htm>.
- ^ a b c d e f g "Nairovirus." Nairovirus. Viral Zone. <http://www.expasy.ch/viralzone/all_by_species/251.html>.
- ^ Honig JE, Osborne JC, Nichol ST (2004) The high genetic variation of viruses of the genus Nairovirus reflects the diversity of their predominant tick hosts. Virology 318(1):10-16
External links
| Taxon identifiers |
- Wikidata: Q3067948
- EoL: 80607
- IRMNG: 1014261
- NCBI: 11592
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