Mitoviridae

Mitoviridae is a family of RNA viruses that primarily infect fungi. These viruses are characterized by their simple genome structure and their unique replication mechanism within the host's mitochondria. The family Mitoviridae is currently unassigned to any order.

Structure

Mitoviridae viruses are non-enveloped and possess a simple, linear, positive-sense, single-stranded RNA genome. The genome is typically around 2.3 to 3.6 kilobases in length. Unlike many other viruses, Mitoviridae do not form traditional virions; instead, they exist as naked RNA molecules within the host cell.

Genome

The genome of Mitoviridae encodes a single open reading frame (ORF) that translates into a RNA-dependent RNA polymerase (RdRp). This enzyme is crucial for the replication of the viral RNA within the host's mitochondria. The lack of additional structural proteins is a distinctive feature of this family, as it relies entirely on the host cell's machinery for replication and transmission.

Replication

Mitoviridae replicate within the mitochondria of their fungal hosts. The replication process begins with the synthesis of a complementary negative-sense RNA strand by the RdRp, which then serves as a template for the production of new positive-sense RNA genomes. These new genomes can either be translated to produce more RdRp or packaged into new viral particles for transmission to other cells.

Transmission

Transmission of Mitoviridae occurs primarily through cytoplasmic exchange between fungal cells, such as during cell division or hyphal fusion. There is no evidence of extracellular transmission, as these viruses do not form traditional virions.

Host Range

Mitoviridae primarily infect fungi, including important plant pathogens such as those in the genera Cryphonectria and Ophiostoma. The presence of mitoviruses can sometimes attenuate the virulence of their fungal hosts, a phenomenon that has been explored for potential biological control applications.

Taxonomy

The family Mitoviridae contains a single genus, Mitovirus. Within this genus, there are several species, each typically named after the host fungus from which it was first isolated.

Research and Applications

Research into Mitoviridae has focused on their unique replication mechanisms and their potential use in controlling fungal diseases. The ability of some mitoviruses to reduce the virulence of their host fungi has led to interest in their use as biological control agents.

Also see

• RNA virus
• Fungal virology
• RNA-dependent RNA polymerase
• Biological control