Identification of a novel polymycovirus infecting the entomopathogenic fungus Metarhizium robertsii.

Mycoviruses studies have been increasing in the last few years. Most of them are focused on the ability of the virus to positively or negatively affect the virulence of their host. Hypervirulence-associated mycoviruses infecting important entomopathogenic fungi such as Metarhizium anisopliae or Beauveria bassiana increase their pathogenicity against lepidopteran pests, and with it, their potential as biocontrol agents. In this work, we characterized a novel four-segmented dsRNA mycovirus isolate from Metarhizium robertsii. The mycovirus is a member of the family Polymycoviridae that we have named "Metarhizium robertsii polymycovirus 1" (MrPmV1). Polymycoviridae is an orphan family within the realm Riboviria without any order-to-kingdom taxa assigned. The polymycoviruses are closely related to members of the Hadakaviridae, a family of (+)ssRNA mycoviruses. Because of this, we suggest that both families should be assigned to the same phylum, class, and order.