Cypovirus
Encyclopedia
Cypoviruses are a genus
of virus
es 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
. The virions are embedded in a protein matrix to form the structures referred to as polyhedra or occlusion bodies.
Cypoviruses have only been isolated from insect
s. Morphologically, these viruses have much in common with the much more widely studied nucleopolyhedroviruses (NPV), a genus of arthropod viruses in the Baculovirus
family. However, CPV have an RNA genome and replicate in the cytoplasm of the infected cells while NPV have a DNA genome and replicate in the nucleus.
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 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.
Genus
In biology, a genus is a low-level taxonomic rank used in the biological classification of living and fossil organisms, which is an example of definition by genus and differentia...
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 in 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 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
RNA
Ribonucleic acid , or RNA, is one of the three major macromolecules that are essential for all known forms of life....
. The virions are embedded in a protein matrix to form the structures referred to as polyhedra or occlusion bodies.
Cypoviruses have only been isolated from insect
Insect
Insects are a class of living creatures within the arthropods that have a chitinous exoskeleton, a three-part body , three pairs of jointed legs, compound eyes, and two antennae...
s. Morphologically, these viruses have much in common with the much more widely studied nucleopolyhedroviruses (NPV), a genus of arthropod viruses in the Baculovirus
Baculovirus
The baculoviruses are a family of large rod-shaped viruses that can be divided to two genera: nucleopolyhedroviruses and granuloviruses . While GVs contain only one nucleocapsid per envelope, NPVs contain either single or multiple nucleocapsids per envelope. The enveloped virions are further...
family. However, CPV have an RNA genome and replicate in the cytoplasm of the infected cells while NPV have a DNA genome and replicate in the nucleus.
Structure and proteins
CPVs are classified into 14 species based on the electrophoreticElectrophoresis
Electrophoresis, also called cataphoresis, is the motion of dispersed particles relative to a fluid under the influence of a spatially uniform electric field. This electrokinetic phenomenon was observed for the first time in 1807 by Reuss , who noticed that the application of a constant electric...
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
Methylase
A methylase is an enzyme that attaches a methyl group to a molecule.These are found in prokaryotes and eukaryotes. Bacteria use methylase to differentiate between foreign genetic material and their own, thus protecting their DNA from their own immune system...
domains with a highly conserved helix
Helix
A helix is a type of smooth space curve, i.e. a curve in three-dimensional space. It has the property that the tangent line at any point makes a constant angle with a fixed line called the axis. Examples of helixes are coil springs and the handrails of spiral staircases. A "filled-in" helix – for...
-pair/β-sheet/helix-pair sandwich fold but lacks the β-barrel flap present in orthoreovirus λ2
Lambda phage
Enterobacteria phage λ is a temperate bacteriophage that infects Escherichia coli.Lambda phage is a virus particle consisting of a head, containing double-stranded linear DNA as its genetic material, and a tail that can have tail fibers. The phage particle recognizes and binds to its host, E...
. 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.