Mammalian orthoreovirus

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Mammalian orthoreovirus
Virus classification OOjs UI icon edit-ltr.svg
(unranked): Virus
Realm: Riboviria
Kingdom: Orthornavirae
Phylum: Duplornaviricota
Class: Resentoviricetes
Order: Reovirales
Family: Sedoreoviridae
Genus: Orthoreovirus
Species:Mammalian orthoreovirus
Serotypes [1]

Mammalian orthoreovirus (MRV) is a double-stranded RNA virus. It is a part of the family Reoviridae , as well as the subfamily Spinareovirinae . As seen in the name, the Mammalian Ortheoreovirus infects numerous mammalian species and vertebrates which serve as natural hosts. Some diseases that occur as a result of this virus or are associated with this virus include mild upper respiratory illness, and gastrointestinal illness. Examples of these are: upper respiratory tract syndromes, gastroenteritis (stomach flu), biliary atresia, obstructive hydrocephalus, jaundice, alopecia, conjunctivitis, and ‘oily hair’ associated with steatorrhea. [3] [4]

Contents

There are four serotypes, or distinct variations within the viral species, of Mammalian orthoreovirus. This means that there are four separate strains of Mammalian orthoreovirus: Type 1 Lang, Type 2 Jones, Type 3 Dearing, Type 4 Ndelle. An example of these strains is Mammalian orthoreovirus type 3, or Mammalian orthoreovirus 3-Dearing (MRV-3; Strain Dearing). It induces cell death preferentially in transformed cells and therefore displays inherent oncolytic properties. [4] [5]

It is believed that Mammalian orthoreovirus causes subclinical infection in humans more so than in other mammals. Meaning, that a human infected with Mammalian orthoreovirus, regardless of the serotype, is nearly or completely asymptomatic, and therefore, don't exhibit signs or symptoms of the virus. This theory is based upon evidence that the majority of people have antibodies for all of the serotypes, meaning they were exposed to the virus at some point and the body's immune system built an immunity to it after being infected. [3]

Viral classification

Baltimore Classification Baltimore Classification.svg
Baltimore Classification

Based upon the Baltimore classification scheme, the Mammalian orthoreovirus is a Group III virus. This is because the Mammalian orthoreovirus is a double stranded RNA virus, and as stated previously, a part of the Reovirus family. The name “Reo-“is derived from respiratory enteric orphan diseases. The term “orphan diseases” makes reference to the fact that some Reoviruses were not known to be associated with any diseases at the time of their discovery. The Reoviridae family is also characterized with "naked", icosahedral capsids and 10-12 segments of linear double stranded RNA. “Naked” meaning the icosahedral capsid is not surrounded by a viral envelope. [6]

Within the Reoviridae family the Mammalian orthoreovirus is a part of the Spinareovirinae subfamily. This is based on the fact that viruses within this subfamily, such as the Mammalian orthoreovirus, Aquareovirus, Coltivirus, Cypovirus, etc., have the presence of a turreted protein on the inner capsid. [5] [7]

History

Phylogenetic comparison of the viral polymerase protein sequences of viruses of the family Reoviridae. Reovirus phylogenetics.jpg
Phylogenetic comparison of the viral polymerase protein sequences of viruses of the family Reoviridae.

The etymology of the Mammalian orthoreovirus is based upon “ortho-“ translated from Greek as “straight” and “reovirus“ from respiratory enteric orphan virus. [7] The Mammalian orthoreovirus was labeled an orphan virus in the 1950s when it was discovered. It was described as a “ubiquitous presence” in mammals meaning it was found virtually everywhere. Serum surveys conducted in the 1950s found neutralizing antibodies to mammalian orthoreovirus in humans, monkeys, rabbits and guinea pigs. More recent studies suggest that MRV is still a ubiquitous presence in humans. The Mammalian orthoreovirus is well researched and understood on the biochemical and structural levels, additionally their pathogenesis in mice serves as a model system for studying the pathogenesis of the reoviruses in general. The Orthoreovirus genus is subdivided into fusogenic and non-fusogenic. The division is based upon fusogenic orthoreoviruses having the ability to cause fusion of infected cells, resulting in multinucleated cellular syncytia. These fusogenic orthoreoviruses encode a fusion-associated small transmembrane (FAST) protein that is plays a role in this ability. Prototypical Mammailian orthoreovirsus are non-fusogenic, and do not produce syncytia because of the lack of the fusion-associated transmembrane protein. [4] [7]

The Mammalian orthoreovirus serotypes have been studied significantly at the antigenetic and sequence levels. Serotypes 1 (Lang), 2 (Jones), and 3 (Dearing) were originally recognized based upon virus neutralization and hemaglutination-inhibition profiles. Serotype 4 (Ndelle) have been studied at the antigenetic and molecular levels. [4] [6] [8]

Structure and genome

Just as the rest of the reoviruses are structured, the Mammalian orthoreovirus contains a segmented genome with a linear genomic arrangement, which is enclosed in a 70-80 nm double layered protein capsid, made up of an inner (T=2) and outer layer (T=13). The viral core of MRV, and orthoreoviruses alike, consist of an inner capsid layer plus its enclosed viral genome. The Mammalian orthoreovirus double stranded RNA genome contains 10 segments divided into three size classes (small, medium, and large) based upon their characteristic mobility during gel electrophoresis. The genome has three large segments, (L1, L2, and L3) which encode for λ (lambda) proteins; three medium segments (M1, M2, and M3) that encode for μ (mu) proteins; and four small segments (S1, S2, S3, and S4) which encode for σ (sigma) proteins. In total, the genome size is approximately 23,500 base pairs. [6] [7] [8]

Structure of Mammalian orthoreovirus Structure of the reovirus virion.png
Structure of Mammalian orthoreovirus

Generally, these double stranded RNA genome segments contain a single gene encoding a single protein, although there are some exceptions. The S1 genome segment of the non-fusogenic reoviruses (e.g., Mammalian orthoreovirus) encode the σ1 cell attachment protein. Contained with the σ1 gene is a second, smaller open reading frame encoding the non-structural σ1s. Reovirus double stranded RNA, cannot serve as a template for protein translation or as messenger RNA (mRNA). Because of the nature of double stranded RNA, double stranded RNA viruses such as reoviruses, and the Mammalian orthoreovirus must carry and/or encode the necessary enzymes within their virions in order to first transcribe their genome, producing mRNA, and delivering their infectious mRNA into the cytoplasm of the host cell. The double stranded RNA viral core, which plays an important role in packaging the genome and the transcription of mRNA as well as maturation, contain proteins which are present across the entire Type 3 double stranded RNA group. In the outer capsid layer, the proteins take part in the role of environmental stability, and cell attachment to a number of hosts, which are quite variable even within the same Orthoreovirus genus. [6]

The internal structure of MRV has been fully reconstructed. λ3 is the RNA replicase, whereas μ2 is a transcription factor. [9]

Replication cycle

As stated in the beginning of the article, the natural hosts of the Mammalian orthoreovirus are mammals, ranging from pigs to humans, and the majority of all mammalian species. This is why the Mammalian orthoreovirus is described as a ubiquitous presence, because antibodies for one (or more) serotypes have been found in virtually every mammalian species. This is at least partially due to because the Mammalian orthoreovirus does not rely on arthropods for transmission as many viruses do. Instead the Mammalian orthoreovirus is transmitted via the oral-fecal route, meaning in some way an infected host's feces are ingested by another person, or the aerosol route, meaning the viral particles travel through the air and are breathed in by a person. [6] [7] [10]

Entry into cell

Once inside the person the Mammalian orthoreovirus attaches to target cells via the σ1 protein, a filamentous trimer that protrudes from the outer capsid layer. Junctional adhesion molecule-A is a receptor for the Mammalian orthoreovirus regardless of the serotype. Sialic acid, resident within the respiratory system of most mammals is a co-receptor for Mammalian orthoreovirus Type 3 (Dearing). After binding to the receptors on the surface of the to-be host cell, the virus is brought into the cell via receptor-mediated endocytosis. Following the internalization of the virus, the viral outer capsid is disassembled within the endocytic compartment (the vesicle). This disassembly of the outer capsid of the virus is performed by endocytic proteases, during acidic pH conditions. This leads to the removal of the σ3 protein, resulting in the exposure of micro1, a membrane-penetration mediator, as well as a conformational change in the σ1 attachment protein. [7] [10] [11] [12]

Replication and transcription

After the uncoated virus particles penetrate the endosomes, early transcription of the double stranded RNA genome by viral polymerase occurs inside the uncoated (naked) viral core. This process occurs in this manner so the viral double stranded RNA is not exposed to the cytoplasm, as this would cause the cell to attack the viral particle. The viral core is then released into the cytoplasm of the host cell, where replication occurs. Replication is completed with the aid of protein λ3, which acts as RNA-dependent RNA polymerase. Positive-strand transcripts from each of the double stranded RNA segments are synthesized, these transcripts are then used as templates for the translation of proteins, in addition to make the negative-strand RNA. Viral protein μ2, is a transcriptase cofactor that is a part of transcription, it also has enzymatic functions such as capping the mRNA, and acts as RNA helicase, which separates double stranded RNA strands. [7] [11] [13] [14]

Assembly and release

Mammalian orthoreovirus messenger RNA transcripts have a short 5’ untranslated region, and do not have 3’ poly A tails, some lack 5’ caps during post-infection. It is unknown as to how uncapped versions of MRV's mRNA are able to use a host cell ribosome in translation. Mammalian orthoreovirus’ viral proteins and its genomic RNAs aggregate in cytoplasm viral factories. The positive and negative RNA stands will base pair to create the double stranded RNA viral genome. The virion is assembled in sub-viral particles in the cytoplasm. Due to the nature of the Mammalian orthoreovirus, its outer (T=13) and inner (T=2) capsid are self-assembled. The inner capsid proteins require the co-expression of the T2 protein and the σ2 protein, to stabilize the inner capsid structure as well as aid in assembly. The outer capsid's assembly is dependent upon the σ3 viral protein, which aids in the formation of the icosahedral capsid. After the virus has been fully assembled and matured, the newly formed Mammalian orthoreovirus particle is released from the host cell, the means in which the virus particle does this is uncertain but it is presumed to happen following cell death and the breakdown of the host plasma membrane. [7] [11] [13]

Interaction with hosts

The Mammalian orthoreovirus as stated previously is ubiquitous among mammals, infecting a large variety of species all over the world. Examples include, pigs, cattle, horses, primates, dogs, cats, rabbits, mice, marsupials, and humans. Experimental infection of Mammalian orthoreovirus Type 3 resulted in 100% mortality in neonatal pigs, the pigs developed acute gastroenteritis and severe diarrhea within 72 hours of infection. Additionally, it has been reported that MRV-3 causes enteritis, pneumonia, encephalitis and reproductive failure in swine. Experimental infection of Mammalian orthoreovirus Type 1 resulted in pneumonia, enteritis, fever, and diarrhea. [15] [16]

Related Research Articles

<span class="mw-page-title-main">Sedoreoviridae</span> Family of viruses

Sedoreoviridae is a family of double-stranded RNA viruses. Member viruses have a wide host range, including vertebrates, invertebrates, plants, protists and fungi. They lack lipid envelopes and package their segmented genome within multi-layered capsids. Lack of a lipid envelope has allowed three-dimensional structures of these large complex viruses to be obtained, revealing a structural and likely evolutionary relationship to the cystovirus family of bacteriophage. There are currently 97 species in this family, divided among 15 genera in two subfamilies. Reoviruses can affect the gastrointestinal system and respiratory tract. The name "reo-" is an acronym for "respiratory enteric orphan" viruses. The term "orphan virus" refers to the fact that some of these viruses have been observed not associated with any known disease. Even though viruses in the family Reoviridae have more recently been identified with various diseases, the original name is still used.

<i>Foot-and-mouth disease virus</i> Species of virus

Foot-and-mouth disease virus (FMDV) is the pathogen that causes foot-and-mouth disease. It is a picornavirus, the prototypical member of the genus Aphthovirus. The disease, which causes vesicles (blisters) in the mouth and feet of cattle, pigs, sheep, goats, and other cloven-hoofed animals is highly infectious and a major plague of animal farming.

<span class="mw-page-title-main">Viral replication</span> Formation of biological viruses during the infection process

Viral replication is the formation of biological viruses during the infection process in the target host cells. Viruses must first get into the cell before viral replication can occur. Through the generation of abundant copies of its genome and packaging these copies, the virus continues infecting new hosts. Replication between viruses is greatly varied and depends on the type of genes involved in them. Most DNA viruses assemble in the nucleus while most RNA viruses develop solely in cytoplasm.

<i>Orbivirus</i> Genus of viruses

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.

<i>Orthoreovirus</i> Genus of viruses

Orthoreovirus is a genus of viruses, in the family Reoviridae, in the subfamily Spinareovirinae. Vertebrates serve as natural hosts. There are ten species in this genus. Diseases associated with this genus include mild upper respiratory tract disease, gastroenteritis, and biliary atresia. Mammalian orthoreovirus 3 induces cell death preferentially in transformed cells and therefore displays inherent oncolytic properties.

<i>Cypovirus</i> Genus of viruses

Cypovirus, short for cytoplasmic polyhedrosis virus, is a genus of double-stranded RNA viruses in the family Reoviridae and subfamily Spinareovirinae. Cypoviruses have only been isolated from insects. Diseases associated with this genus include chronic diarrhoea and pale blue iridescence in the guts of larvae. Sixteen species are placed in this genus.

<span class="mw-page-title-main">Golden shiner virus</span> Species of virus

The golden shiner virus is an aquatic virus that infects a bait fish known as the golden shiner and to a lesser extent, aquatic animals like crustaceans and molluscs. About 6 virus species have been identified in this genus since the late 1970s. It causes death through a hemorrhagic shock. Symptoms include bleeding from the back eyes and the head. The virus is 70 nm in diameter and replicates best at 20-30 degrees Celsius. The virus has properties similar to those of the pancreatic necrosis virus. This could mean that golden shiners are more susceptible in the summer.

<i>Coltivirus</i> Genus of viruses

Coltivirus is a genus of viruses that infects vertebrates and invertebrates. It includes the causative agent of Colorado tick fever. Colorado tick fever virus can cause a fever, chills, headache, photophobia, myalgia, arthralgia, and lethargy. Children, in particular, may develop a hemorrhagic disease. Leukopenia with both lymphocytes and neutrophils is very common for Colorado tick fever virus. In either case, the infection can lead to encephalitis or meningitis.

<i>Fijivirus</i> Genus of viruses

Fijivirus is a genus of double-stranded RNA viruses in the family Reoviridae and subfamily Spinareovirinae. Plants serve as natural hosts. Diseases associated with this genus include: galls (tumours) in infected plants and Fiji disease, with severe stunting, deformation and death. The group name derives from Fiji island the place where the first virus was isolated. There are nine species in this genus.

<span class="mw-page-title-main">Double-stranded RNA viruses</span> Type of virus according to Baltimore classification

Double-stranded RNA viruses are a polyphyletic group of viruses that have double-stranded genomes made of ribonucleic acid. The double-stranded genome is used as a template by the viral RNA-dependent RNA polymerase (RdRp) to transcribe a positive-strand RNA functioning as messenger RNA (mRNA) for the host cell's ribosomes, which translate it into viral proteins. The positive-strand RNA can also be replicated by the RdRp to create a new double-stranded viral genome.

<i>Phytoreovirus</i> Genus of viruses

Phytoreovirus is a genus of viruses, in the family Reoviridae, in the subfamily Sedoreovirinae. They are non-turreted reoviruses that are major agricultural pathogens, particularly in Asia. Oryza sativa for RDV and RGDV, dicotyledonous for WTV, and leafhoppers serve as natural hosts. There are three species in this genus. Diseases associated with this genus include: WTV: galls (tumor). RDV: dwarf disease of rice. RGDV: dwarfing, stunting, and galls.

Avian orthoreovirus, also known as avian reovirus, is an orthoreovirus from the Reoviridae family. Infection causes arthritis and tenosynovitis in poultry. It can also cause respiratory disease.

Xi River virus (XRV) is a putative novel bat virus in the genus Orthoreovirus isolated from fruit bats in Guangdong Province in southern China. It is the first bat reovirus isolated in China.

Melaka virus(MELV) is a bat-borne virus. It was first isolated in a human in Melaka, Malaysia in 2006. A bat reservoir was suspected because traceback analysis revealed that the patient had been exposed to a bat prior to the onset of infection. Melaka virus causes a non-fatal respiratory tract illness in humans.

<i>Sedoreovirinae</i> Subfamily of viruses

Sedoreovirinae was a subfamily of the Reoviridae family of viruses. Viruses in this subfamily are distinguished by the absence of a turreted protein on the inner capsid to produce a smooth surface.

Epizootic hemorrhagic disease virus, often abbreviated to EHDV, is a species of the genus Orbivirus, a member of the family Reoviridae. It is the causative agent of epizootic hemorrhagic disease, an acute, infectious, and often fatal disease of wild ruminants. In North America, the most severely affected ruminant is the white-tailed deer, although it may also infect mule deer, black-tailed deer, elk, bighorn sheep, and pronghorn antelope. It is often mistakenly referred to as “bluetongue virus” (BTV), another Orbivirus that like EHDV causes the host to develop a characteristic blue tongue due to systemic hemorrhaging and lack of oxygen in the blood. Despite showing clinical similarities, these two viruses are genetically distinct.

Idnoreovirus is a genus of double-stranded RNA viruses in the family Reoviridae and subfamily Spinareovirinae. Hymenoptera insects serve as natural hosts. The genus name is an acronym for insect derived non occluded reovirus. There are five species in this genus.

<i>Dinovernavirus</i> Genus of viruses

Dinovernavirus is a genus of double-stranded RNA viruses in the family Reoviridae and subfamily Spinareovirinae. Member viruses replicate in a variety of mosquito cell lines. The name is an abbreviation for double-stranded, insect, novem, rna virus. There is one species in the genus: Aedes pseudoscutellaris reovirus.

Mimoreovirus is a genus of viruses, in the family Reoviridae, in the subfamily Sedoreovirinae. The only isolate infects the marine photosynthetic protist Micromonas pusilla, a prasinophyte. There is only one species in this genus: Micromonas pusilla reovirus.

<i>Piscine orthoreovirus</i> Species of virus

Piscine orthoreovirus (PRV) is a species in the genus Orthoreovirus that infects fish exclusively, PRV was first discovered in 2010 in farmed Atlantic salmon exhibiting Heart and Skeletal Muscle Inflammation (HSMI) and has been found present at higher concentration in fish with various diseases. These diseases include HSMI, jaundice syndrome, proliferative darkening syndrome and erythrocytic body inclusion syndrome. PRV is thought to mainly affect aquacultured and maricultured fish stocks, and recent research has been focused around the susceptibility of wild stock. However, whether PRV is virulent with respect to HSMI remains a topic of debate. PRV has been in the public eye mostly due to a potential linkage to farmed Atlantic Salmon exhibiting HSMI. Public concern has been raised regarding the possibility of open ocean-net farms transmitting PRV to wild salmon populations and being a factor in declining populations. PRV has not been confirmed to be pathogenic in wild salmon stocks.

References

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  2. ↑ Mahy, Brian W J (2001). A dictionary of virology (3. ed.). San Diego, Calif. [u.a.]: Academic Press. pp.  1. ISBN   978-0-12-465327-6.
  3. 1 2 "disease.html". web.stanford.edu. Retrieved 2017-11-04.
  4. 1 2 3 4 Mahy, Brian W. J. (2009-02-26). The Dictionary of Virology. Academic Press. ISBN   9780080920368.
  5. 1 2 Liu, Dongyou (2016-05-25). Molecular Detection of Animal Viral Pathogens. CRC Press. ISBN   9781498700375.
  6. 1 2 3 4 5 Day, J. Michael (February 6, 2009). "The diversity of the orthoreoviruses: Molecular taxonomy and phylogentic divides". Infection, Genetics and Evolution. 9 (4): 390–400. doi:10.1016/j.meegid.2009.01.011. PMID   19460305.
  7. 1 2 3 4 5 6 7 8 "Orthoreovirus". viralzone.expasy.org. Retrieved 2017-11-04.
  8. 1 2 Center for Food Security and Public Health, College of Veterinary Medicine, Iowa State University (July 2016). "Orthoreovirus" (PDF). swinehealth.org.
  9. ↑ Pan, M; Alvarez-Cabrera, AL; Kang, JS; Wang, L; Fan, C; Zhou, ZH (7 July 2021). "Asymmetric reconstruction of mammalian reovirus reveals interactions among RNA, transcriptional factor μ2 and capsid proteins". Nature Communications. 12 (1): 4176. doi: 10.1038/s41467-021-24455-4 . PMC   8263624 . PMID   34234134.
  10. 1 2 Attachment and Cell Entry of Mammalian Orthoreovirus (PDF Download Available). Vol. 309. February 2006. Retrieved 2017-11-04.{{cite book}}: |website= ignored (help)
  11. 1 2 3 Bussiere, Luke D.; Choudhury, Promisree; Bellaire, Bryan; Miller, Cathy L. (2017-11-15). "Characterization of a Replicating Mammalian Orthoreovirus with Tetracysteine-Tagged μNS for Live-Cell Visualization of Viral Factories". Journal of Virology. 91 (22). doi:10.1128/JVI.01371-17. ISSN   1098-5514. PMC   5660500 . PMID   28878073.
  12. ↑ Guglielmi, K. M.; Johnson, E. M.; Stehle, T.; Dermody, T. S. (2006). Attachment and cell entry of mammalian orthoreovirus. Current Topics in Microbiology and Immunology. Vol. 309. pp. 1–38. doi:10.1007/3-540-30773-7_1. ISBN   978-3-540-30772-3. ISSN   0070-217X. PMID   16909895.
  13. 1 2 Eichwald, Catherine; Kim, Jonghwa; Nibert, Max L. (2017). "Dissection of mammalian orthoreovirus μ2 reveals a self-associative domain required for binding to microtubules but not to factory matrix protein μNS". PLOS ONE. 12 (9): e0184356. Bibcode:2017PLoSO..1284356E. doi: 10.1371/journal.pone.0184356 . ISSN   1932-6203. PMC   5589220 . PMID   28880890.
  14. ↑ Stuart, Johnasha D.; Phillips, Matthew B.; Boehme, Karl W. (2017). "Reverse Genetics for Mammalian Orthoreovirus". Reverse Genetics of RNA Viruses. Methods in Molecular Biology. Vol. 1602. pp. 1–10. doi:10.1007/978-1-4939-6964-7_1. ISBN   978-1-4939-6962-3. ISSN   1940-6029. PMID   28508210.
  15. ↑ Qin, Pan; Li, Huan; Wang, Jing-Wei; Wang, Bin; Xie, Rong-Hui; Xu, Hui; Zhao, Ling-Yan; Li, Long; Pan, Yongfei (September 2017). "Genetic and pathogenic characterization of a novel reassortant mammalian orthoreovirus 3 (MRV3) from a diarrheic piglet and seroepidemiological survey of MRV3 in diarrheic pigs from east China". Veterinary Microbiology. 208: 126–136. doi:10.1016/j.vetmic.2017.07.021. ISSN   1873-2542. PMC   7117289 . PMID   28888627.
  16. ↑ Lelli, Davide; Beato, Maria Serena; Cavicchio, Lara; Lavazza, Antonio; Chiapponi, Chiara; Leopardi, Stefania; Baioni, Laura; De Benedictis, Paola; Moreno, Ana (2016-08-12). "First identification of mammalian orthoreovirus type 3 in diarrheic pigs in Europe". Virology Journal. 13: 139. doi: 10.1186/s12985-016-0593-4 . ISSN   1743-422X. PMC   4983005 . PMID   27519739.
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