Hypovirus

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Hypoviridae
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Hypovirus
Virus classification Edit this 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]

Species

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]

Structure

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

RNA replicase–helicase. [3]

Life cycle

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

CHV1 – Chestnut blight hypovirulence

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]

References

  1. ^
    PMID 29589826
    .
  2. ^ a b "Virus Taxonomy: 2020 Release". International Committee on Taxonomy of Viruses (ICTV). March 2021. Retrieved 20 May 2021.
  3. ^ a b c d "Viral Zone". ExPASy. Retrieved 15 June 2015.
  4. PMID 32038565
    .
  5. ^ "ICTV report: Hypoviridae". Ictv.global. Retrieved 31 December 2021.
  6. ^
    PMID 11055936
    . Retrieved 13 August 2014.
  7. .
  8. ^ "Sweet chestnut blight (Cryphonectria parasitica)". Forestry Commission, UK. Retrieved 13 August 2014.

External links