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]
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]