Orthoreovirus
Encyclopedia
Orthoreoviruses are members of the Reoviridae
virus
family
. They have double stranded RNA
genome
s and are therefore group III viruses. These viruses infect vertebrates (including humans) but no disease symptoms are normally seen. In some cases however, orthoreovirus infection can lead to complications, especially in mice and birds.
The structure of the virus particles is complex. The virus is non-enveloped and has icosahedral symmetry with a triangulation number of 13. It can be compared to a wheel with spokes radiating out of it. The virus has a double protein
shell. The outer shell is approximately 80 nm in diameter and the inner shell is 60 nm in diameter.
The genome
can be divided into three main classes: L (large), M (medium) and S (small). The L genes encode λ proteins, the M genes encode μ proteins and the S genes encode σ proteins.
σ1, σ3, λ2 and μ1c proteins make up in the outer capsid
. Proteins λ1, λ3, σ2 and μ2 make up the inner capsid.
Replication of the virus takes place in the host cell
cytoplasm
.
Like other members of the Reoviridae
family, the reoviruses are non-enveloped and characterized by concentric capsid shells that encapsidate a segmented dsRNA genome
. A 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 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).
Reoviridae
Reoviridae is a family of viruses that can affect the gastrointestinal system and respiratory tract. Viruses in the family Reoviridae have genomes consisting of segmented, double-stranded RNA...
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...
family
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...
. They have 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...
genome
Genome
In modern molecular biology and genetics, the genome is the entirety of an organism's hereditary information. It is encoded either in DNA or, for many types of virus, in RNA. The genome includes both the genes and the non-coding sequences of the DNA/RNA....
s and are therefore group III viruses. These viruses infect vertebrates (including humans) but no disease symptoms are normally seen. In some cases however, orthoreovirus infection can lead to complications, especially in mice and birds.
The structure of the virus particles is complex. The virus is non-enveloped and has icosahedral symmetry with a triangulation number of 13. It can be compared to a wheel with spokes radiating out of it. The virus has a double protein
Protein
Proteins are biochemical compounds consisting of one or more polypeptides typically folded into a globular or fibrous form, facilitating a biological function. A polypeptide is a single linear polymer chain of amino acids bonded together by peptide bonds between the carboxyl and amino groups of...
shell. The outer shell is approximately 80 nm in diameter and the inner shell is 60 nm in diameter.
The genome
Genome
In modern molecular biology and genetics, the genome is the entirety of an organism's hereditary information. It is encoded either in DNA or, for many types of virus, in RNA. The genome includes both the genes and the non-coding sequences of the DNA/RNA....
can be divided into three main classes: L (large), M (medium) and S (small). The L genes encode λ proteins, the M genes encode μ proteins and the S genes encode σ proteins.
σ1, σ3, λ2 and μ1c proteins make up in the outer 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...
. Proteins λ1, λ3, σ2 and μ2 make up the inner capsid.
Replication of the virus takes place in the host cell
Cell (biology)
The cell is the basic structural and functional unit of all known living organisms. It is the smallest unit of life that is classified as a living thing, and is often called the building block of life. The Alberts text discusses how the "cellular building blocks" move to shape developing embryos....
cytoplasm
Cytoplasm
The cytoplasm is a small gel-like substance residing between the cell membrane holding all the cell's internal sub-structures , except for the nucleus. All the contents of the cells of prokaryote organisms are contained within the cytoplasm...
.
Like other members of the Reoviridae
Reoviridae
Reoviridae is a family of viruses that can affect the gastrointestinal system and respiratory tract. Viruses in the family Reoviridae have genomes consisting of segmented, double-stranded RNA...
family, the reoviruses are non-enveloped and characterized by concentric capsid shells that encapsidate a segmented dsRNA genome
Genome
In modern molecular biology and genetics, the genome is the entirety of an organism's hereditary information. It is encoded either in DNA or, for many types of virus, in RNA. The genome includes both the genes and the non-coding sequences of the DNA/RNA....
. A 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 the proteins of mammalian reovirus (MRV), which is the best-studied genotype. Electron cryo-microscopy (cryoEM) and X-ray crystallography
Crystallography
Crystallography is the experimental science of the arrangement of atoms in solids. The word "crystallography" derives from the Greek words crystallon = cold drop / frozen drop, with its meaning extending to all solids with some degree of transparency, and grapho = write.Before the development of...
have provided a wealth of structural information about two specific MRV strains, type 1 Lang (T1L) and type 3 Dearing (T3D).
External links
- MicrobiologyBytes - Reoviruses
- Viralzone: Orthoreovirus