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47-653: MRV can refer to: Mammalian orthoreovirus Merovingian Music , a record label Mini-rotary viscometer Multiple reentry vehicle MRV Communications , an American company MRV Engenharia , a Brazilian homebuilder company The IATA code for Mineralnye Vody Airport Magnetic resonance venography , a variation of magnetic resonance angiography Magnetic resonance velocimetry , an experimental method to obtain velocity fields in fluid mechanics Medium reconnaissance vehicle, an Australian M113 armored personnel carrier variant "Measurable, reportable, verifiable" –

94-405: 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

141-417: A Gag-Pol fusion protein (180 kDa) formed by a -1 ribosomal frameshift. L-A can support the replication and encapsidation in separate viral particles of any of several satellite dsRNAs, called M dsRNAs, each of which encodes a secreted protein toxin (the killer toxin) and immunity to that toxin. L-A and M are transmitted from cell to cell by the cytoplasmic mixing that occurs in the process of mating. Neither

188-596: A diverse range of eukaryotes, and cystoviruses , which are the only dsRNA viruses known to infect prokaryotes. Apart from RdRp, viruses in Duplornaviricota also share icosahedral capsids that contain 60 homo- or heterodimers of the capsid protein organized on a pseudo T=2 lattice. The phylum is divided into three classes: Chrymotiviricetes , which primarily contains fungal and protozoan viruses, Resentoviricetes , which contains reoviruses, and Vidaverviricetes , which contains cystoviruses. The class Duplopiviricetes

235-404: A highly conserved helix -pair/β-sheet/helix-pair sandwich fold but lacks the β-barrel flap present in orthoreovirus λ2 . The stacking of turret protein functional domains and the presence of constrictions and A spikes along the mRNA release pathway indicate a mechanism that uses pores and channels to regulate the highly coordinated steps of RNA transcription, processing, and release. Rotavirus

282-573: A term qualifying carbon emissions reductions in contexts such as deforestation ( REDD ) Roll Flight MR V , a German powered parachute design Topics referred to by the same term [REDACTED] This disambiguation page lists articles associated with the title MRV . If an internal link led you here, you may wish to change the link to point directly to the intended article. Retrieved from " https://en.wikipedia.org/w/index.php?title=MRV&oldid=1225936422 " Category : Disambiguation pages Hidden categories: Short description

329-451: 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. 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

376-481: Is a double-stranded RNA non-enveloped virus. The members of genus Orbivirus within the Reoviridae family are arthropod borne viruses and are responsible for high morbidity and mortality in ruminants . Bluetongue virus (BTV) which causes disease in livestock ( sheep , goat , cattle ) has been in the forefront of molecular studies for the last three decades and now represents the best understood orbivirus at

423-458: Is a member of the Cystoviridae family. It infects Pseudomonas bacteria (typically plant-pathogenic P. syringae ). It has a three-part, segmented, double-stranded RNA genome, totalling ~13.5 kb in length. Φ6 and its relatives have a lipid membrane around their nucleocapsid, a rare trait among bacteriophages . It is a lytic phage, though under certain circumstances has been observed to display

470-609: 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. 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

517-412: 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. Once inside

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564-401: Is different from Wikidata All article disambiguation pages All disambiguation pages Mammalian orthoreovirus 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

611-414: Is naturally released from the cell or enters cells by other mechanisms, but the high frequency of yeast mating in nature results in the wide distribution of these viruses in natural isolates. Moreover, the structural and functional similarities with dsRNA viruses of mammals has made it useful to consider these entities as viruses. Infectious bursal disease virus (IBDV) is the best-characterized member of

658-431: 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

705-428: Is the most common cause of acute gastroenteritis in infants and young children worldwide. This virus contains a dsRNA genome and is a member of the Reoviridae family. The genome of rotavirus consists of eleven segments of dsRNA. Each genome segment codes for one protein with the exception of segment 11, which codes for two proteins. Among the twelve proteins, six are structural and six are non-structural proteins. It

752-699: Is the second clade of dsRNA viruses and is in the phylum Pisuviricota , which also contains positive-sense single-stranded RNA viruses. Duplopiviricetes mostly contains plant and fungal viruses and includes the following four families: Amalgaviridae , Hypoviridae , Partitiviridae , and Picobirnaviridae . Reoviridae are currently classified into nine genera . The genomes of these viruses consist of 10 to 12 segments of dsRNA , each generally encoding one protein . The mature virions are non-enveloped. Their capsids, formed by multiple proteins, have icosahedral symmetry and are arranged generally in concentric layers. The orthoreoviruses ( reoviruses ) are

799-402: 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

846-440: 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

893-537: The electrophoretic migration profiles of their genome segments. Cypovirus has only a single capsid shell, which is similar to the orthoreovirus inner core. CPV exhibits striking capsid stability and is fully capable of endogenous RNA transcription and processing. The overall folds of CPV proteins are similar to those of other reoviruses. However, CPV proteins have insertional domains and unique structures that contribute to their extensive intermolecular interactions. The CPV turret protein contains two methylase domains with

940-436: The rotaviruses , known globally as a common cause of gastroenteritis in young children, and bluetongue virus , an economically significant pathogen of cattle and sheep. The family Reoviridae is the largest and most diverse dsRNA virus family in terms of host range. Two clades of dsRNA viruses exist: the phylum Duplornaviricota and the class Duplopiviricetes , which is in the phylum Pisuviricota . Both are included in

987-455: 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. Based upon the Baltimore classification scheme,

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1034-463: 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. 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

1081-402: 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

1128-493: 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

1175-472: 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,

1222-448: The RdRp to create a new double-stranded viral genome. A distinguishing feature of the dsRNA viruses is their ability to carry out transcription of the dsRNA segments within the capsid , and the required enzymes are part of the virion structure. Double-stranded RNA viruses are classified into two phyla, Duplornaviricota and Pisuviricota (specifically class Duplopiviricetes ), in

1269-413: The capsid proteins and a plausible model for capsid assembly have been derived. While the structural proteins of RDV share no sequence similarity to other proteins, their folds and the overall capsid structure are similar to those of other Reoviridae . The L-A dsRNA virus of the yeast Saccharomyces cerevisiae has a single 4.6 kb genomic segment that encodes its major coat protein, Gag (76 kDa) and

1316-519: The capsid proteins of some positive-sense single-stranded RNA viruses, such as the nodaviruses and tetraviruses , as well as the T  = 13 capsid shell protein of the Reoviridae . The T  = 13 shell of the IBDV capsid is formed by trimers of VP2, a protein generated by removal of the C-terminal domain from its precursor, pVP2. The trimming of pVP2 is performed on immature particles as part of

1363-476: The family Birnaviridae . These viruses have bipartite dsRNA genomes enclosed in single layered icosahedral capsids with T  = 13l geometry. IBDV shares functional strategies and structural features with many other icosahedral dsRNA viruses, except that it lacks the T  = 1 (or pseudo T  = 2) core common to the Reoviridae , Cystoviridae , and Totiviridae . The IBDV capsid protein exhibits structural domains that show homology to those of

1410-401: The genome size is approximately 23,500 base pairs. 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

1457-520: The kingdom Orthornavirae and realm Riboviria . The two phyla do not share a common dsRNA virus ancestor, but evolved their double strands two separate times from positive-strand RNA viruses . In the Baltimore classification system, dsRNA viruses belong to Group III. Virus group members vary widely in host range ( animals , plants , fungi , and bacteria ), genome segment number (one to twelve), and virion organization ( T-number , capsid layers, or turrets). Double-stranded RNA viruses include

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1504-475: The kingdom Orthornavirae in the realm Riboviria . Based on phylogenetic analysis of RdRp, the two clades do not share a common dsRNA ancestor but are instead separately descended from different positive-sense, single-stranded RNA viruses. In the Baltimore classification system, which groups viruses together based on their manner of mRNA synthesis, dsRNA viruses are group III. Duplornaviricota contains most dsRNA viruses, including reoviruses , which infect

1551-409: The lack of the fusion-associated transmembrane protein. 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. Just as

1598-402: The maturation process. The other major structural protein, VP3, is a multifunctional component lying under the T  = 13 shell that influences the inherent structural polymorphism of pVP2. The virus-encoded RNA-dependent RNA polymerase , VP1, is incorporated into the capsid through its association with VP3. VP3 also interacts extensively with the viral dsRNA genome. Bacteriophage Φ6 ,

1645-545: The molecular and structural levels. BTV, like other members of the family, is a complex non-enveloped virus with seven structural proteins and a RNA genome consisting of 10 variously sized dsRNA segments. Phytoreoviruses are non-turreted reoviruses that are major agricultural pathogens, particularly in Asia. One member of this family, Rice Dwarf Virus (RDV), has been extensively studied by electron cryomicroscopy and x-ray crystallography . From these analyses, atomic models of

1692-606: 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 . 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,

1739-449: 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

1786-405: 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

1833-439: 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 . Double-stranded RNA viruses Double-stranded RNA viruses ( dsRNA viruses ) are

1880-446: The presence of a turreted protein on the inner capsid. The etymology of the Mammalian orthoreovirus is based upon “ortho-“ translated from Greek as “straight” and “reovirus“ from r espiratory e nteric o rphan virus. 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

1927-416: The proteins of mammalian reovirus (MRV), which is the best-studied genotype. Electron cryo- microscopy (cryoEM) and X-ray crystallography have provided a wealth of structural information about two specific MRV strains, type 1 Lang (T1L) and type 3 Dearing (T3D). The cytoplasmic polyhedrosis viruses (CPVs) form the genus Cypovirus of the family Reoviridae . CPVs are classified into 14 species based on

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1974-530: The prototypic members of the virus Reoviridae family and representative of the turreted members, which comprise about half the genera. Like other members of the family, the reoviruses are non-enveloped and characterized by concentric capsid shells that encapsidate a segmented dsRNA genome . In particular, reovirus has eight structural proteins and ten segments of dsRNA. A series of uncoating steps and conformational changes accompany cell entry and replication. High-resolution structures are known for almost all of

2021-408: 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

2068-481: 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

2115-840: 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,

2162-572: The same Orthoreovirus genus. The internal structure of MRV has been fully reconstructed. λ3 is the RNA replicase, whereas μ2 is a transcription factor. 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

2209-412: The σ3 protein, resulting in the exposure of micro1, a membrane-penetration mediator, as well as a conformational change in the σ1 attachment protein. 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

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