Orthonairovirus | |
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Crimean-Congo hemorrhagic fever orthonairovirus virion and genome | |
Virus classification | |
(unranked): | Virus |
Realm: | Riboviria |
Kingdom: | Orthornavirae |
Phylum: | Negarnaviricota |
Class: | Ellioviricetes |
Order: | Bunyavirales |
Family: | Nairoviridae |
Genus: | Orthonairovirus |
Orthonairovirus is a genus of viruses in the family Nairoviridae of the order Bunyavirales that include viruses with circular, negative-sense single stranded RNA. [1] It got its name from the Nairobi sheep disease that affects the gastrointestinal tracts of sheep and goats. [1] The vast majority, and perhaps all viruses in this genus are tick-borne viruses that can have human or other vertebrate hosts. [2]
The virions for viruses in this genus have a spherical shape. [3] 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. [1] The ribonucleocapsid is filamentous, having a length of about 200-300 nm and a width of about 2–2.5 nm. [1] 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. [1] They aid in attachment to the host receptor in replication.
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. [2] The large segment is about 11000–14400 nucleotides long (11–14.4 kb), and it encodes the viral polymerase. [1] [3] 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. [1] [3] The small segment is about 1,700–2,100 nucleotides long (1.7–2.1 kb), and it encodes the nucleocapsid protein. [2] < [1] [3]
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. [1] Both the 5’ and 3’ ends have conserved regions, 9 nucleotides in length. The sequences are, 5’end: UCUCAAAGA, and 3’end: AGAGUUUCU. [1]
Nairoviruses attach to the host receptor by their Gn-Gc glycoprotein dimer. [3] The virus is then endocytosed into the host cell via a vesicle. The ribonucleocapsid segments are released into the cytoplasm, commencing transcription. [3] Transcription and replication occur within the cell, and the newly synthesized virions are released by budding.
Members of this viral genus infect many different vertebrate hosts, and are transmitted via ticks. [1]
Members of the genus Nairovirus may be found the world over, wherever their arthropod vectors and vertebrate hosts are found together. [3]
Only four viruses in this genus have, to date, been recognised as human pathogens:
A fifth— Erve virus —may also be pathogenic for humans.
Phylogenetic analysis has shown that these viruses fall into two major monophyletic groups, the hard ( Ixodidae ) and soft ( Argasidae ) tick-vectored groups. [4] 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
The soft bodied tick serogroups are
The tick vectors for the Kasokero and Thiafora serogroups are not currently known.
The genus includes 41 species: [5]
Flaviviridae is a family of enveloped positive-strand RNA viruses which mainly infect mammals and birds. They are primarily spread through arthropod vectors. The family gets its name from the yellow fever virus; flavus is Latin for "yellow", and yellow fever in turn was named because of its propensity to cause jaundice in victims. There are 89 species in the family divided among four genera. Diseases associated with the group include: hepatitis (hepaciviruses), hemorrhagic syndromes, fatal mucosal disease (pestiviruses), hemorrhagic fever, encephalitis, and the birth defect microcephaly (flaviviruses).
Bunyavirales is an order of segmented negative-strand RNA viruses with mainly tripartite genomes. Member viruses infect arthropods, plants, protozoans, and vertebrates. It is the only order in the class Ellioviricetes. The name Bunyavirales derives from Bunyamwera, where the original type species Bunyamwera orthobunyavirus was first discovered. Ellioviricetes is named in honor of late virologist Richard M. Elliott for his early work on bunyaviruses.
An arenavirus is a bi- or trisegmented ambisense RNA virus that is a member of the family Arenaviridae. These viruses infect rodents and occasionally humans. A class of novel, highly divergent arenaviruses, properly known as reptarenaviruses, have also been discovered which infect snakes to produce inclusion body disease. At least eight arenaviruses are known to cause human disease. The diseases derived from arenaviruses range in severity. Aseptic meningitis, a severe human disease that causes inflammation covering the brain and spinal cord, can arise from the lymphocytic choriomeningitis virus. Hemorrhagic fever syndromes, including Lassa fever, are derived from infections such as Guanarito virus, Junin virus, Lassa virus, Lujo virus, Machupo virus, Sabia virus, or Whitewater Arroyo virus. Because of the epidemiological association with rodents, some arenaviruses and bunyaviruses are designated as roboviruses.
Crimean–Congo hemorrhagic fever (CCHF) is a viral disease. Symptoms of CCHF may include fever, muscle pains, headache, vomiting, diarrhea, and bleeding into the skin. Onset of symptoms is less than two weeks following exposure. Complications may include liver failure. In those who survive, recovery generally occurs around two weeks after onset.
Mardivirus is a genus of viruses in the order Herpesvirales, in the family Herpesviridae, in the subfamily Alphaherpesvirinae. Chickens, turkeys, and quail serve as natural hosts. There are six species in this genus. Diseases associated with this genus include: Marek's disease, which causes asymmetric paralysis of one or more limbs, neurological symptoms, and development of multiple lymphomas that manifest as solid tumors. Gallid herpesvirus 2 is the only one of these viruses known to be pathogenic and due to the antigenic similarity between the three viruses the other two have been used to vaccinate against Marek's disease. These viruses have double stranded DNA genomes with no RNA intermediate.
Thogotovirus is a genus of enveloped RNA viruses, one of seven genera in the virus family Orthomyxoviridae. Their single-stranded, negative-sense RNA genome has six or seven segments. Thogotoviruses are distinguished from most other orthomyxoviruses by being arboviruses – viruses that are transmitted by arthropods, in this case usually ticks. Thogotoviruses can replicate in both tick cells and vertebrate cells; one subtype has also been isolated from mosquitoes. A consequence of being transmitted by blood-sucking vectors is that the virus must spread systemically in the vertebrate host – unlike influenza viruses, which are transmitted by respiratory droplets and are usually confined to the respiratory system.
Orbivirus is a genus of double-stranded RNA viruses in the family Reoviridae and subfamily Sedoreovirinae. Unlike other reoviruses, orbiviruses are arboviruses. They can infect and replicate within a wide range of arthropod and vertebrate hosts. Orbiviruses are named after their characteristic doughnut-shaped capsomers.
Argentinian mammarenavirus, better known as the Junin virus or Junín virus (JUNV), is an arenavirus in the Mammarenavirus genus that causes Argentine hemorrhagic fever (AHF). The virus took its original name from the city of Junín, around which the first cases of infection were reported, in 1958.
Orthobunyavirus is a genus of the Peribunyaviridae family in the order Bunyavirales. There are currently ~170 viruses recognised in this genus. These have been assembled into 103 species and 20 serogroups.
Lagovirus is a genus of viruses, in the family Caliciviridae. Lagomorphs serve as natural hosts. There are two species in this genus. Diseases associated with this genus include: necrotizing hepatitis leading to fatal hemorrhages.
Kupe orthonairovirus, also called Kupe virus, is a species of virus in the genus Orthonairovirus.
Cilevirus is a genus of viruses in the family Kitaviridae. Plants serve as natural hosts. There are two species: Citrus leprosis virus C and Citrus leprosis virus C2.
In 1954 the Hazara orthonairovirus, one of the 34 tick-borne viruses of the genus Orthonairovirus, was discovered in Pakistan in the Ixodes tick native to that region. Today this virus is studied in mice in an attempt to develop treatments for the highly pathogenic Crimean-Congo Hemorrhagic Fever virus.
Batai orthobunyavirus (BATV) is a RNA virus belonging to order Bunyavirales, genus Orthobunyavirus.
Cache Valley orthobunyavirus (CVV) is a member of the order Bunyavirales, genus Orthobunyavirus, and serogroup Bunyamwera, which was first isolated in 1956 from Culiseta inornata mosquitos collected in Utah's Cache Valley. CVV is an enveloped arbovirus, nominally 80–120 nm in diameter, whose genome is composed of three single-stranded, negative-sense RNA segments. The large segment of related bunyaviruses is approximately 6800 bases in length and encodes a probable viral polymerase. The middle CVV segment has a 4463-nucleotide sequence and the smallest segment encodes for the nucleocapsid, and a second non-structural protein. CVV has been known to cause outbreaks of spontaneous abortion and congenital malformations in ruminants such as sheep and cattle. CVV rarely infects humans, but when they are infected it has caused encephalitis and multiorgan failure.
Quaranjavirus is a genus of enveloped RNA viruses, one of seven genera in the virus family Orthomyxoviridae. The genome is single-stranded, negative-sense segmented RNA, generally with six segments. The genus contains two species: Johnston Atoll virus and Quaranfil virus; it has been proposed to contain species or strains including Cygnet River virus, Lake Chad virus, Tyulek virus and Wellfleet Bay virus. Quaranjaviruses predominantly infect arthropods and birds; As of March 2015, Quaranfil quaranjavirus is the only member of the genus to have been shown to infect humans. The Quaranfil and Johnston Atoll viruses are transmitted between vertebrates by ticks, resembling members of Thogotovirus, another genus of Orthomyxoviridae.
Nairoviridae is a family of viruses in the order Bunyavirales. Its name derives from Nairobi sheep disease, caused by the member Nairobi sheep disease orthonairovirus.
The Nairobi sheep disease orthonairovirus (NSDV), also known as Ganjam virus is a species in the genus Orthonairovirus belonging to the Nairobi sheep disease serogroup. NSDV's known hosts belong to the hard tick family Ixodidae, including Rhipicephalus appendiculatus, and Amblyomma variegatum, and afflict sheep and goats naturally. The virus is in the family Nairoviridae and order Bunyavirales.
The Tofla virus is a strain of Hazara orthonairovirus in the genus Orthonairovirus belonging to the Crimean-Congo hemorrhagic fever serogroup. It was isolated from Ixodid in Japan in 2016.
Farallon virus is a strain of Hughes orthonairovirus in the genus Orthonairovirus belonging to the Hughes serogroup. A known host of the virus is Ornithodoros. The virus is named after the Farallon Islands.