| Batai orthobunyavirus | |
|---|---|
Virus classification  | |
| (unranked): | Virus |
| Realm: | Riboviria |
| Kingdom: | Orthornavirae |
| Phylum: | Negarnaviricota |
| Class: | Ellioviricetes |
| Order: | Bunyavirales |
| Family: | Peribunyaviridae |
| Genus: | Orthobunyavirus |
| Species: | Batai orthobunyavirus |
| Synonyms | |
| |
Batai orthobunyavirus (BATV) is a RNA virus belonging to order Bunyavirales , genus Orthobunyavirus .
Batai virus (BATV) is an enveloped, single-stranded, negative sense RNA genome. [1] It is a member of the genus Orthobunyavirus and belongs to the order Bunyavirales; it was first isolated from Culex mosquitoes in Malaysia in 1955. [2] Evidence from serological surveillance and virus isolation shows that this virus is widely distributed around the world. Similar to other orthobunyaviruses it contributes to both human and animal disease. In humans it has been noted in causing severe fever, and in bovines has been associated with premature birth, birth defects, and increased abortion rates. It is transmitted through mosquito bites, ticks, and biting midges, and occurs from cold to tropical regions of Africa, Asia, and Europe. [2]
The structure of Batai virus (BATV) consists of an enveloped nucleocapsid that is composed of three RNA segments: small (S), medium (M), and large (L). The S segment encodes the nucleocapsid (N) and the non-structural (NSs) proteins. The M segment encodes the virion surface glycoproteins (Gn, Gc) and non-structural proteins (NSm). The L segment encodes for the replicase/ transcriptase L protein. The nonstructural proteins NSm participate in virus assembly and NSs plays a key role in counteracting the host immune response by blocking alpha/beta interferon induction [3] The full-length genome of NM/12 consists of a 947 base pair nucleotide S segment, a 4405 base pair nucleotide M segment, and a 6870 base pair nucleotide L segment. It also contains one open reading frame that encode three proteins of 151, 943, or 1395 amino acids. [2]
Viral enveloped nucleocapsids utilize membrane glycoproteins on their surface to mediate entry into host cells. Averaging of glycoprotein spikes of membrane viruses, such as HIV-1, has been a particularly successful approach for studying their structure. [4] An understanding of the structure is integral for revealing both the molecular basis of virus–host interactions and guiding antiviral and vaccine design development. A software named Jsubtomo enables visualization of the structure of viral glycoprotein spikes to a resolution in the range of 20-40 Å and allows for study of the study of higher order spike-to-spike interactions on the virion membrane. [4]
Extensive research has yet to be performed on the detailed crystalline structure of Batai virus, but research on the closely related Bunyamwera virus has shown a distinct functionality of each of the two nucleocapsid side chains. An N-terminal arm and a C-terminal tail were found to interact with neighboring NP protomers to form a tetrameric ring-shaped organization. Each protomer bound a 10-nucleotide RNA molecule, which was acquired from the expression host, in the positively charged crevice between the N and C lobes. [5] Cryo-electron microscopy has also determined that whilst Bunyamwera virions are pleomorphic in shape, they display a locally ordered lattice of glycoprotein spikes. Each spike protrudes 18 nanometers from the viral membrane and becomes disordered upon introduction to an acidic environment. [6]
Although the exact icosahedral symmetry of a Batai virus viron is yet to be determined, studies using Cryo-electron tomography on related viruses of the Bunyaviridae family have shown that there exists an icosahedral lattice with clear T=12 quasisymmetry. [7] Consequently, this triangulation number would correlate with a viral nuclear capsid exhibiting 720 faces. This study was performed on the Rift Valley Fever Virus (RVFV), which is an arthropod borne disease that is endemic to regions of Africa and Asia, namely the Rift Valley in Kenya from which its name is derived. [8]
Batai virus is a member of the genus Orthobunyavirus and a member of the family Bunyaviridae. [9] Batai virus is part of a diverse group of arthropod-borne viruses. [9] Classified via the Baltimore scheme, Batai virus is a negative-sense, single-stranded RNA virus. [9] The orthobunyavirus genome has a characteristic segmented genome, with small, medium, and large (S, M, and L) segments which generally encode the nucleocapsid, envelope protein and the polymerase protein, respectively. [9] The size of the S segment is 943 nucleotides, the size of the M segment is 4440 nucleotides, and the size of the L segment is 6870 nucleotides. [9] In the S segment there are two open reading frames (ORFs), the nucleocapsid and non-structurals which were overlapping. [9] The M segment has a polyprotein precursor in the open reading frame. [9] The L segment encodes for an RNA-dependent RNA polymerase. [9]
Batai virus is geographically spread throughout Asia and Europe. It has been shown that batai viruses from Japan, Malaysia and India share homologies in the genomic sequence more so than when virus strains from Europe and Asia are compared to each other. Reassortment of the genome can have some serious effects. It has been observed that reassortment between the M segment and the S and L segments with another strain of Batai virus (BUNV) can cause an increase in the virulence of Batai virus. Reassortment of the genome within the genus Orthobunyavirus are not uncommon and can lead to an increase in virulence. [2]
It is well known that the geographical distribution of Batai virus (BATV) includes the regions of Europe, Asia and Africa. The most common vertebrate affected by BATV are domestic pigs, horses, ruminants and wild birds, which have been known to be the primary mammalian hosts. The transmission cycle of BATV occurs in agricultural ecosystems via Anopheles, Culex and Ochlerotatus species mosquitoes in a typical vertebrate–mosquito cycle. [9]
While limited research has been conducted on the viral cycle of the Batai virus, comparable studies with the close relative Bunyamwera virus has shown that viral infection begins in the salivary glands of mosquitos. [10] At the onset of replication the virus particles coalesce into vacuole membranes lining the cytoplasm of the infected cells. [11] Entry into the cell is facilitated by the viral enveloped nucleocapsid, which contains glycoproteins G1 and G2. Encoded by the M RNA segment they are involved in attachment to the host cell through unidentified receptors on the surface and elicit neutralizing antibodies. Transcription of BATV is said to be similar to that of influenza in that mRNA synthesis is primed by cap-containing oligonucleotides that are generated by a certain viral-endonuclease, functioning to cleave the host cell mRNA. These resulting primers are then incorporated into the viral mRNA. [12] BATV will also encode for two non-structural proteins, NSm on the M segment and NSs on the S segment. During the process it is believed that NSm actively participates in assembly of the virus. These newly assembled viral particles will mature over a period of time inside of the hosts cell in the membranes of the Golgi apparatus before being released. [11]
However, while able to replicate in both vertebrate and invertebrate species, in mosquito cells no cell death is observed and persistent infection is established. Whereas in mammalian cells infection is typically categorized as lytic and eventually leads to cell death. This stems from the viruses ability to form clear lytic plaques in cells of vertebrate species but not in those derived from insects. [13] It has been demonstrated in previous studies that in mammalian cells, the NSs protein will induce a shut-off of host protein synthesis which will lead to the death of the host cell. It has also been shown to counteract the host cell antiviral response. [14] This would establish it as the main virulence factor as it acts during the transcriptional phase by inhibiting RNA polymerase II–mediated transcription. Meanwhile, the mosquito cells neither host cell transcription nor translation are inhibited by this fact. It would seem the difference in the behavior of the NSs protein could be one of the factors responsible for the different outcomes of infection attributed to the Batai virus in mammalian and mosquito cells. Some have theorized that a release method that does not rupture the cell membrane could explain why viral replication does not kill mosquito cells and persistence is maintained. [13] Similar NSs proteins of the Rift Valley fever phlebovirus have quite a distinct size and amino acid sequence, but they play a similar role in mammalian cells in overcoming the innate immune responses that are a consequence of the global shut-down of the cells transcription mechanisms. Similar NSs proteins of the Rift Valley fever phlebovirus have quite a distinct size and amino acid sequence, but they play a similar role in mammalian cells in overcoming the innate immune responses that are a consequence of the global shut-down of the cells transcription mechanisms. [15]
Batai virus (BATV) is a member of the family Bunyaviridae. [2] Associated viruses include Crimean-Congo hemorrhagic fever, Bunyamwera orthobunyavirus , and severe fever with thrombocytopenia syndrome. [16]
Crimean-Congo hemorrhagic fever is one of the viruses that is associated with Batai virus, as it is in the same family Bunyaviridae. This occurs in the same areas throughout the world including Africa, Asia, Europe. It mainly infects farmworkers in these regions of the world, and is a tick-borne illness. Infection results in high fever, chills, severe headache, dizziness, back, and abdominal pains. Other symptoms that have been noted include nausea, vomiting, diarrhea, and cardiovascular and neuropsychiatric changes. If severe symptoms may include hemorrhages in the skin, causing lesions or bruising. It has a 30% fatality rate. [17]
A closely associated disease is the Bunyamwera virus, which is of the same family and genus as the Batai virus (BATV); it is known to cause Bunyamwera fever. This particular virus is spread by mosquitos biting infected mice and then biting humans. [18]
Batai virus (BATV) is also associated with severe fever with thrombocytopenia syndrome (SFTS). This was a recently discovered in China in 2011 and is transmitted either directly to humans through ticks, or to house pets as an intermediate host and then on to humans. Symptoms are characterized by fever, vomiting, diarrhea, thrombocytopenia and leukopenia. SFTS virus has a 6-30% fatality rate. [19]
Rift Valley fever (RVF) is a viral disease of humans and livestock that can cause mild to severe symptoms. The mild symptoms may include: fever, muscle pains, and headaches which often last for up to a week. The severe symptoms may include: loss of sight beginning three weeks after the infection, infections of the brain causing severe headaches and confusion, and bleeding together with liver problems which may occur within the first few days. Those who have bleeding have a chance of death as high as 50%.
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.
Lassa mammarenavirus (LASV) is an arenavirus that causes Lassa hemorrhagic fever, a type of viral hemorrhagic fever (VHF), in humans and other primates. Lassa mammarenavirus is an emerging virus and a select agent, requiring Biosafety Level 4-equivalent containment. It is endemic in West African countries, especially Sierra Leone, the Republic of Guinea, Nigeria, and Liberia, where the annual incidence of infection is between 300,000 and 500,000 cases, resulting in 5,000 deaths per year.
Bwamba orthobunyavirus (BWAV) belongs to the genus Orthobunyavirus and the order Bunyavirales RNA viruses. BWAV is present in large parts of Africa, endemic in Mozambique, Tanzania and Uganda. It is transmitted to humans through mosquito bites and results in a brief benign generalised infection with headache, skin rash, diarrhea and joint pain and lasts 4–5 days. The animal reservoir of the virus includes birds, monkeys and donkeys.
Oropouche fever is a tropical viral infection transmitted by biting midges and mosquitoes from the blood of sloths to humans. This disease is named after the region where it was first discovered and isolated at the Trinidad Regional Virus Laboratory in 1955 by the Oropouche River in Trinidad and Tobago. Oropouche fever is caused by a specific arbovirus, the Oropouche virus (OROV), of the Bunyaviridae family.
Alphavirus is a genus of RNA viruses, the sole genus in the Togaviridae family. Alphaviruses belong to group IV of the Baltimore classification of viruses, with a positive-sense, single-stranded RNA genome. There are 32 alphaviruses, which infect various vertebrates such as humans, rodents, fish, birds, and larger mammals such as horses, as well as invertebrates. Alphaviruses that could infect both vertebrates and arthropods are referred dual-host alphaviruses, while insect-specific alphaviruses such as Eilat virus and Yada yada virus are restricted to their competent arthropod vector. Transmission between species and individuals occurs mainly via mosquitoes, making the alphaviruses a member of the collection of arboviruses – or arthropod-borne viruses. Alphavirus particles are enveloped, have a 70 nm diameter, tend to be spherical, and have a 40 nm isometric nucleocapsid.
The genome and proteins of HIV (human immunodeficiency virus) have been the subject of extensive research since the discovery of the virus in 1983. "In the search for the causative agent, it was initially believed that the virus was a form of the Human T-cell leukemia virus (HTLV), which was known at the time to affect the human immune system and cause certain leukemias. However, researchers at the Pasteur Institute in Paris isolated a previously unknown and genetically distinct retrovirus in patients with AIDS which was later named HIV." Each virion comprises a viral envelope and associated matrix enclosing a capsid, which itself encloses two copies of the single-stranded RNA genome and several enzymes. The discovery of the virus itself occurred two years following the report of the first major cases of AIDS-associated illnesses.
Phlebovirus is one of twenty genera of the family Phenuiviridae in the order Bunyavirales. The genus contains 66 species. It derives its name from Phlebotominae, the vectors of member species Naples phlebovirus, which is said to be ultimately from the Greek phlebos, meaning "vein". The proper word for "vein" in ancient Greek is however phleps (φλέψ).
A viral envelope is the outermost layer of many types of viruses. It protects the genetic material in their life cycle when traveling between host cells. Not all viruses have envelopes. A viral envelope protein or E protein is a protein in the envelope, which may be acquired by the capsid from an infected host cell.
Andes orthohantavirus (ANDV), a species of Orthohantavirus, is a major causative agent of hantavirus cardiopulmonary syndrome (HCPS) and hantavirus pulmonary syndrome (HPS) in South America. It is named for the Andes mountains of Chile and Argentina, where it was first discovered. Originating in the reservoir of rodents, Andes orthohantavirus is easily transmitted to humans who come into contact with infected rodents or their fecal droppings. However, infected rodents do not appear ill, so there is no readily apparent indicator to determine whether the rodent is infected or not. Additionally, Andes orthohantavirus, specifically, is the only hantavirus that can be spread by human to human contact via bodily fluids or long-term contact from one infected individual to a healthy person.
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.
Bunyamwera orthobunyavirus (BUNV) is a negative-sense, single-stranded enveloped RNA virus. It is assigned to the Orthobunyavirus genus, in the Bunyavirales order.
Dabie bandavirus, also called SFTS virus, is a tick-borne virus in the genus Bandavirus in the family Phenuiviridae, order Bunyavirales. The clinical condition it caused is known as severe fever with thrombocytopenia syndrome (SFTS). SFTS is an emerging infectious disease that was first described in northeast and central China 2009 and now has also been discovered in Japan, South Korea, Vietnam and Taiwan in 2015. SFTS has a fatality rate of 12% and as high as over 30% in some areas. The major clinical symptoms of SFTS are fever, vomiting, diarrhea, multiple organ failure, thrombocytopenia, leukopenia and elevated liver enzyme levels. Another outbreak occurred in East China in the early half of 2020.
Tahyna orthobunyavirus ("TAHV") is a viral pathogen of humans classified in the California encephalitis virus (CEV) serogroup of the Orthobunyavirus family in the order Bunyavirales, which is endemic to Europe, Asia, Africa and possibly China.
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.
Phenuiviridae is a family of negative-strand RNA viruses in the order Bunyavirales. Ruminants, camels, humans, and mosquitoes serve as natural hosts. Member genus Phlebovirus is the only genus of the family that has viruses that cause disease in humans except Dabie bandavirus.
Middelburg virus (MIDV) is an alphavirus of the Old World Group that has likely endemic and zoonotic potential. It is of the viral family Togaviridae. It was isolated from mosquitos in 1957 in South Africa, MDIV antigens have now been found in livestock, horses, and humans.
Rio Negro virus is an alphavirus that was first isolated in Argentina in 1980. The virus was first called Ag80-663 but was renamed to Rio Negro virus in 2005. It is a former member of the Venezuelan equine encephalitis complex (VEEC), which are a group of alphaviruses in the Americas that have the potential to emerge and cause disease. Río Negro virus was recently reclassified as a distinct species. Closely related viruses include Mucambo virus and Everglades virus.
Bunyaviridae nonstructural S proteins (NSs) are synthesized by viral DNA/RNA and do not play a role in the replication or the viral protein coating. The nonstructural S segment (NSs) created by Bunyaviridae virus family, are able to interact with the human immune system, in order to increase their replication in infected cells. Understanding this mechanism can have global health impacts.
Ngari virus (NRIV) is a single-stranded, negative sense, tri-segmented RNA virus. It is a subtype of the Bunyamwera virus (BUNV) and closely related to the Batai virus (BATV). NRIV is the only reassortment virus of the subtypes. There is evidence suggesting that NRIV stems from a naturally occurring reassortment event in which a host was infected with both BUNV and BATV. It is commonly found in areas that experience an outbreak of Rift Valley fever virus (RFVF)