Reoviridae
Encyclopedia
Reoviridae is a family
of virus
es that can affect the gastrointestinal system (such as Rotavirus
) and respiratory tract
. Viruses in the family Reoviridae have genomes consisting of segmented, double-stranded RNA
(dsRNA). The name "Reoviridae" is derived from respiratory enteric
orphan viruses. The term "orphan virus" means that a virus that is not associated with any known disease. Even though viruses in the Reoviridae family have more recently been identified with various diseases, the original name is still used.
Reovirus infection occurs often in humans, but most cases are mild or subclinical. The virus can be readily detected in feces, and may also be recovered from pharyngeal or nasal secretions, urine, cerebrospinal fluid, and blood. Despite the ease of finding Reovirus in clinical specimens, their role in human disease or treatment is still uncertain.
Some viruses of this family infect plants. For example, Phytoreovirus
and Oryzavirus.
capsid
(T-13) composed of an outer and inner protein shell. The genomes of viruses in Reoviridae contain 10-12 segments which are grouped into three categories corresponding to their size: L (large), M (medium) and S (small). Segments range from ~ 3.9 kbp – 1kbp and each segment encodes 1-3 proteins. Reoviridae proteins are denoted by the Greek character corresponding to the segment it was translated from (the L segment encodes for λ proteins, the M segment encodes for μ proteins and the S segment encodes for σ proteins).
Since these viruses have dsRNA genomes, replication occurs exclusively in the cytoplasm and the virus encodes several proteins which are needed for replication and conversion of the dsRNA genome into (+)-RNAs. The virus can enter the host cell via a receptor on the cell surface. The receptor is not known but is thought to include sialic acid
and junctional adhesion molecules (JAMs). The virus is partially uncoated by proteases in the endolysosome, where the capsid is partially digested to allow further cell entry. The core particle then enters the cytoplasm by a yet unknown process where the genome is transcribed conservatively causing an excess of (+) sense strands, which are used as mRNA templates to synthesize (-) sense strands. Viral particles begin to assemble in the cytoplasm 6–7 hours after infection.
As of July 2009, ratified by the ICTV, there are two subfamilies; Sedoreovirinae & Spinareovirinae in the family Reoviridae.
"The name Spinareovirinae will be used to identify the subfamily containing the spiked or
turreted viruses and is derived from ‘reovirus’ and the Latin word ‘spina’ as a prefix, which
means spike, denoting the presence of spikes or turrets on the surface of the core particles. The
term ‘spiked’ is an alternative to ‘turreted’, that was used in early research to describe the
structure of the particle, particularly with the cypoviruses.
The name Sedoreovirinae will be used to identify the subfamily containing the non-turreted
virus genera and is derived from ‘reovirus’ and the Latin word ‘sedo’, which means smooth,
denoting the absence of spikes or turrets from the core particles of these viruses, which have a
relatively smooth morphology."
The subfamily Sedoreovirinae contains 6 genera:
The subfamily Spinareovirinae contains 9 genera:
Other genera
Crabreovirus
Reolysin
is a formulation of reovirus that is currently in clinical trials for the treatment of various cancers.
Family (biology)
In biological classification, family is* a taxonomic rank. Other well-known ranks are life, domain, kingdom, phylum, class, order, genus, and species, with family fitting between order and genus. As for the other well-known ranks, there is the option of an immediately lower rank, indicated by the...
of virus
Virus
A virus is a small infectious agent that can replicate only inside the living cells of organisms. Viruses infect all types of organisms, from animals and plants to bacteria and archaea...
es that can affect the gastrointestinal system (such as Rotavirus
Rotavirus
Rotavirus is the most common cause of severe diarrhoea among infants and young children, and is one of several viruses that cause infections often called stomach flu, despite having no relation to influenza. It is a genus of double-stranded RNA virus in the family Reoviridae. By the age of five,...
) and respiratory tract
Respiratory tract
In humans the respiratory tract is the part of the anatomy involved with the process of respiration.The respiratory tract is divided into 3 segments:*Upper respiratory tract: nose and nasal passages, paranasal sinuses, and throat or pharynx...
. Viruses in the family Reoviridae have genomes consisting of segmented, double-stranded RNA
Double-stranded RNA viruses
Double-stranded RNA viruses are a diverse group of viruses that vary widely in host range , genome segment number , and virion organization...
(dsRNA). The name "Reoviridae" is derived from respiratory enteric
Enteric
Enteric can refer to:* A general term describing something related to or associated with the intestines** Microorganisms that inhabit the intestines are commonly known as enteric bacteria* Enteric nervous system...
orphan viruses. The term "orphan virus" means that a virus that is not associated with any known disease. Even though viruses in the Reoviridae family have more recently been identified with various diseases, the original name is still used.
Reovirus infection occurs often in humans, but most cases are mild or subclinical. The virus can be readily detected in feces, and may also be recovered from pharyngeal or nasal secretions, urine, cerebrospinal fluid, and blood. Despite the ease of finding Reovirus in clinical specimens, their role in human disease or treatment is still uncertain.
Some viruses of this family infect plants. For example, Phytoreovirus
Phytoreovirus
Phytoreoviruses are non-turreted reoviruses that are major agricultural pathogens, particularly in Asia. One member of this family, Rice Dwarf Virus , has been extensively studied by electron cryomicroscopy and x-ray crystallography. From these analyses, atomic models of the capsid proteins and a...
and Oryzavirus.
Structure
Reoviruses are non-enveloped and have an icosahedralIcosahedron
In geometry, an icosahedron is a regular polyhedron with 20 identical equilateral triangular faces, 30 edges and 12 vertices. It is one of the five Platonic solids....
capsid
Capsid
A capsid is the protein shell of a virus. It consists of several oligomeric structural subunits made of protein called protomers. The observable 3-dimensional morphological subunits, which may or may not correspond to individual proteins, are called capsomeres. The capsid encloses the genetic...
(T-13) composed of an outer and inner protein shell. The genomes of viruses in Reoviridae contain 10-12 segments which are grouped into three categories corresponding to their size: L (large), M (medium) and S (small). Segments range from ~ 3.9 kbp – 1kbp and each segment encodes 1-3 proteins. Reoviridae proteins are denoted by the Greek character corresponding to the segment it was translated from (the L segment encodes for λ proteins, the M segment encodes for μ proteins and the S segment encodes for σ proteins).
Since these viruses have dsRNA genomes, replication occurs exclusively in the cytoplasm and the virus encodes several proteins which are needed for replication and conversion of the dsRNA genome into (+)-RNAs. The virus can enter the host cell via a receptor on the cell surface. The receptor is not known but is thought to include sialic acid
Sialic acid
Sialic acid is a generic term for the N- or O-substituted derivatives of neuraminic acid, a monosaccharide with a nine-carbon backbone. It is also the name for the most common member of this group, N-acetylneuraminic acid...
and junctional adhesion molecules (JAMs). The virus is partially uncoated by proteases in the endolysosome, where the capsid is partially digested to allow further cell entry. The core particle then enters the cytoplasm by a yet unknown process where the genome is transcribed conservatively causing an excess of (+) sense strands, which are used as mRNA templates to synthesize (-) sense strands. Viral particles begin to assemble in the cytoplasm 6–7 hours after infection.
Genera and type species
Fifteen genera of Reoviridae exist and are divided based on the presence of a "turret" protein on the inner capsid.As of July 2009, ratified by the ICTV, there are two subfamilies; Sedoreovirinae & Spinareovirinae in the family Reoviridae.
"The name Spinareovirinae will be used to identify the subfamily containing the spiked or
turreted viruses and is derived from ‘reovirus’ and the Latin word ‘spina’ as a prefix, which
means spike, denoting the presence of spikes or turrets on the surface of the core particles. The
term ‘spiked’ is an alternative to ‘turreted’, that was used in early research to describe the
structure of the particle, particularly with the cypoviruses.
The name Sedoreovirinae will be used to identify the subfamily containing the non-turreted
virus genera and is derived from ‘reovirus’ and the Latin word ‘sedo’, which means smooth,
denoting the absence of spikes or turrets from the core particles of these viruses, which have a
relatively smooth morphology."
The subfamily Sedoreovirinae contains 6 genera:
- Cardoreovirus
- Mimoreovirus
- OrbivirusOrbivirusThe genus Orbivirus is a member of the Reoviridae family. This genus currently contains 22 species and at least 130 different serotypes. Orbiviruses can infect and replicate within a wide range of arthropod and vertebrate hosts...
- PhytoreovirusPhytoreovirusPhytoreoviruses are non-turreted reoviruses that are major agricultural pathogens, particularly in Asia. One member of this family, Rice Dwarf Virus , has been extensively studied by electron cryomicroscopy and x-ray crystallography. From these analyses, atomic models of the capsid proteins and a...
- RotavirusRotavirusRotavirus is the most common cause of severe diarrhoea among infants and young children, and is one of several viruses that cause infections often called stomach flu, despite having no relation to influenza. It is a genus of double-stranded RNA virus in the family Reoviridae. By the age of five,...
- Seadornavirus
The subfamily Spinareovirinae contains 9 genera:
- Aquareovirus
- ColtivirusColtivirusColtivirus is a genus of viruses that infects vertebrates, invertebrates, and plants. It includes the causative agent of Colorado tick fever....
- CypovirusCypovirusCypoviruses are a genus of viruses in the Reoviridae family. The virions have an icosahedral structure typical of other reoviruses and are 55-69 nm in diameter. The genome is composed of 10 segments of double-stranded RNA...
- Dinovernavirus
- FijivirusFijivirus-Taxonomy:The genus Fijivirus is a member of the Reoviridae virus family. These have double-stranded RNA genomes and are therefore group III viruses...
- Idnoreovirus
- Mycoreovirus
- OrthoreovirusOrthoreovirusOrthoreoviruses are members of the Reoviridae virus family. They have double stranded RNA genomes and are therefore group III viruses. These viruses infect vertebrates but no disease symptoms are normally seen. In some cases however, orthoreovirus infection can lead to complications, especially in...
- OryzavirusRice ragged stunt virusRice ragged stunt virus is a plant pathogenic virus of the family Reoviridae.Family: ReoviridaeGenus: OryzavirusSpecies: Rice ragged stunt virusAcronym: RRSV...
Other genera
Crabreovirus
Therapeutic applications
The reovirus has been demonstrated to have oncolytic (cancer-killing) properties and has encouraged the development of reovirus-based therapies for cancer treatment.Reolysin
Reolysin
Reolysin is a formulation of reovirus that Oncolytics Biotech is developing for the treatment of various cancers and cell proliferative disorders. Reolysin is classified as a oncolytic virus, a virus that preferentially lyses cancer cells...
is a formulation of reovirus that is currently in clinical trials for the treatment of various cancers.