| Hypovirus | |
|---|---|
Virus classification  | |
| (unranked): | Virus |
| Realm: | Riboviria |
| Kingdom: | Orthornavirae |
| Phylum: | Pisuviricota |
| Class: | Duplopiviricetes |
| Order: | Durnavirales |
| Family: | Hypoviridae |
| Genus: | Hypovirus |
Hypovirus is a genus of viruses, in the family Hypoviridae. [1] Fungi serve as natural hosts. There are four species in this genus. [2] Infection reduces the virulence of its parasitic host, making it a hyperparasite useful for blight control. [1] [3]
The following species are recognized by the International Committee on Taxonomy of Viruses (ICTV) , all of which were found with Cryphonectria parasitica : [1] [2]
There are numerous family members affecting other plant-pathogenic fungi not yet accepted into the ICTV nomenclature. A proposal reorganizes the family into three genera. [4] The informal family Fusariviridae is the sister group. [5]
The diameter is around 50–80 nm. Genomes are linear, around 9–13kb in length. The genome has 1 or 2 open reading frames, named OrfA (not always present) and OrfB. [1] [3]
| Genus | Structure | Symmetry | Capsid | Genomic arrangement | Genomic segmentation |
|---|---|---|---|---|---|
| Hypovirus | No true capsid | Non-enveloped | Linear | Monopartite |
The genome contains no structural proteins. The virus accordingly does not bud out of the cell (see "life cycle" below). Both open reading frames of CHV1 contain a papain-like protease to the N-terminal that is autocatalyticly cleaved. OrfA (p69, P10941 ) cleaves into the p29 C7 protease and a nonessential p40 protein. OrfB ( Q04350 ) cleaves into a p48 C8 protease and the RNA replicase – helicase. [3]
Viral replication is cytoplasmic. Replication follows the double-stranded RNA virus replication model. Double-stranded RNA virus transcription is the method of transcription. The virus exits the host cell by cell to cell movement. Fungi serve as the natural host. [1] [3]
| Genus | Host details | Tissue tropism | Entry details | Release details | Replication site | Assembly site | Transmission |
|---|---|---|---|---|---|---|---|
| Hypovirus | Fungi | None | Cytoplasmic exchange; hyphal anastomosis | Cytoplasmic exchange; hyphal anastomosis | Cytoplasm | Cytoplasm | Cytoplasmic exchange; hyphal anastomosis |
Up to 2000, Hypovirus CHV1 was the only hypovirus found in Europe. [6] It is known for reducing the virulence of the fungus that causes chestnut blight (i.e. hypovirulence). [7] Cryphonectria parasitica, the ascomycete fungus, originated in Asia and causes the disease chestnut blight in several chestnut species (Castanea spp.). Although symptoms are mild in Asian chestnut species that have co-evolved with the fungus, they are very severe in the North American chestnut species C. dentata and also in the European sweet chestnut, C. sativa. [8] Hypovirus has been used for protection against chestnut blight in Europe since the 1970s. [6]
The pathogenic fungus Cryphonectria parasitica is a member of the Ascomycota. This necrotrophic fungus is native to East Asia and South East Asia and was introduced into Europe and North America in the early 1900s. The fungus spread rapidly and caused significant tree loss in both regions.
Totiviridae is a family of double-stranded RNA viruses. Giardia lamblia, leishmania, trichomonas vaginalis, and fungi serve as natural hosts. The name of the group derives from Latin toti which means undivided or whole. There are 28 species in this family, assigned to 5 genera.
Barnaviridae is a family of non-enveloped, positive-strand RNA viruses. Cultivated mushrooms serve as natural hosts. The family has one genus, Barnavirus, which contains one species: Mushroom bacilliform virus. Diseases associated with this family includes La France disease.
Potyviridae is a family of positive-strand RNA viruses that encompasses more than 30% of known plant viruses, many of which are of great agricultural significance. The family has 12 genera and 235 species, three of which are unassigned to a genus.
Baltimore classification is a system used to classify viruses based on their manner of messenger RNA (mRNA) synthesis. By organizing viruses based on their manner of mRNA production, it is possible to study viruses that behave similarly as a distinct group. Seven Baltimore groups are described that take into consideration whether the viral genome is made of deoxyribonucleic acid (DNA) or ribonucleic acid (RNA), whether the genome is single- or double-stranded, and whether the sense of a single-stranded RNA genome is positive or negative.
Mycoviruses, also known as mycophages, are viruses that infect fungi. The majority of mycoviruses have double-stranded RNA (dsRNA) genomes and isometric particles, but approximately 30% have positive-sense, single-stranded RNA (+ssRNA) genomes.
Totivirus is a genus of double-stranded RNA viruses in the family Totiviridae. Fungi serve as natural hosts. The name of the group derives from Latin toti which means undivided or whole. There are seven species in this genus.
Alphachrysovirus is a genus of double-stranded RNA viruses. It is one of two genera in the family Chrysoviridae. They infect fungi, in particular Penicillium. Their name is derived from the Greek word chrysos which means yellow-green. There are 20 species in this genus.
Teschovirus is a genus of viruses in the order Picornavirales, in the family Picornaviridae. Pigs serve as natural hosts. There are two species in this genus, including Teschovirus A, which is responsible for the porcine enteroviral encephalomyelitis disease caused in pigs. The genus name comes from this species and the disease it causes: Teschen disease, which itself was named for the town Teschen in Poland/Czechoslovakia where the disease was first recognised in 1929.
Benyvirus is a genus of viruses, in the family Benyviridae. Plants serve as natural hosts. There are four species in this genus. Diseases associated with this genus include: BNYVV: rhizomania.
Endornaviridae is a family of viruses. Plants, fungi, and oomycetes serve as natural hosts. There are 31 species in this family, assigned to 2 genera. Members of Alphaendornavirus infect plants, fungi and the oomycete Phytophthora sp., members of Betaendornavirus infect ascomycete fungi.
Alphaflexiviridae is a family of viruses in the order Tymovirales. Plants and fungi serve as natural hosts. There are 65 species in this family, assigned to six genera. Diseases associated with this family include: mosaic and ringspot symptoms.
Gammaflexiviridae is a family of viruses in the order Tymovirales. Fungi serve as natural hosts. There is only one genus in the family, Mycoflexivirus, which has one species: Botrytis virus F.
Mitovirus is a genus of positive-strand RNA viruses, in the family Mitoviridae. Fungi serve as natural hosts. There are five species in the genus.
Mycoreovirus is a genus of double-stranded RNA viruses in the family Reoviridae and subfamily Spinareovirinae. Fungi serve as natural hosts. Diseases associated with this genus include: hypovirulence of the fungal host. The name of the group derives from Ancient Greek myco which means fungus. There are three species in this genus.
Sclerodarnavirus is a genus of viruses in the order Tymovirales, in the family Alphaflexiviridae. Fungi serve as natural hosts. There is only one species in this genus: Sclerotinia sclerotiorum debilitation-associated RNA virus. Diseases associated with this genus include: hypovirulence or debilitation.
Megabirnaviridae is a family of double-stranded RNA viruses with one genus Megabirnavirus which infects fungi. The group name derives from member's bipartite dsRNA genome and mega that is greater genome size than families Birnaviridae and Picobirnaviridae. There is only one species in this family: Rosellinia necatrix megabirnavirus 1. Diseases associated with this family include: reduced host virulence.
Spiraviridae is a family of incertae sedis viruses that replicate in hyperthermophilic archaea of the genus Aeropyrum, specifically Aeropyrum pernix. The family contains one genus, Alphaspiravirus, which contains one species, Aeropyrum coil-shaped virus. The virions of ACV are non-enveloped and in the shape of hollow cylinders that are formed by a coiling fiber that consists of two intertwining halves of the circular DNA strand inside a capsid. An appendage protrudes from each end of the cylindrical virion. The viral genome is ssDNA(+) and encodes for significantly more genes than other known ssDNA viruses. ACV is also unique in that it appears to lack its own enzymes to aid replication, instead likely using the host cell's replisomes. ACV has no known relation to any other archaea-infecting viruses, but it does share its coil-like morphology with some other archaeal viruses, suggesting that such viruses may be an ancient lineage that only infect archaea.
Yokose virus (YOKV) is in the genus Flavivirus of the family Flaviviridae. Flaviviridae are often found in arthropods, such as mosquitoes and ticks, and may also infect humans. The genus Flavivirus includes over 50 known viruses, including Yellow Fever, West Nile Virus, Zika Virus, and Japanese Encephalitis. Yokose virus is a new member of the Flavivirus family that has only been identified in a few bat species. Bats have been associated with several emerging zoonotic diseases such as Ebola and SARS.
Planarian secretory cell nidovirus (PSCNV) is a virus of the species Planidovirus 1, a nidovirus notable for its extremely large genome. At 41.1 kilobases, it is the largest known genome of an RNA virus. It was discovered by inspecting the transcriptomes of the planarian flatworm Schmidtea mediterranea and is the first known RNA virus infecting planarians. It was first described in 2018.