''Quadriviridae'' is a family of

double-stranded RNA viruses Double-stranded RNA viruses (dsRNA viruses) are a polyphyletic group of viruses that have double-stranded genomes made of ribonucleic acid. The double-stranded genome is used as a template by the viral RNA dependent RNA polymerase (RdRp) to ...

with a single genus ''Quadrivirus''. The

fungi A fungus (: fungi , , , or ; or funguses) is any member of the group of eukaryotic organisms that includes microorganisms such as yeasts and mold (fungus), molds, as well as the more familiar mushrooms. These organisms are classified as one ...

Rosellinia necatrix ''Rosellinia'' is a genus of fungi in the family Xylariaceae consisting of over 90 species. Several of the species in this genus are plant pathogens. Fossils of ''Rosellinia'' have been found in 12 million year old rocks from central England. T ...

'' serves as a natural

host A host is a person responsible for guests at an event or for providing hospitality during it. Host may also refer to: Places * Host, Pennsylvania, a village in Berks County * Host Island, in the Wilhelm Archipelago, Antarctica People * ...

. The name of the group derives from the ''quadri''partite genome of its members where in

Latin Latin ( or ) is a classical language belonging to the Italic languages, Italic branch of the Indo-European languages. Latin was originally spoken by the Latins (Italic tribe), Latins in Latium (now known as Lazio), the lower Tiber area aroun ...

''quad'' means four. The genus has three species.

Structure

Mycovirus Mycoviruses (Ancient Greek: μύκης ' ("fungus") + Latin '), also known as mycophages, are viruses that infect fungi. The majority of mycoviruses have dsRNA virus, double-stranded RNA (dsRNA) genomes and isometric particles, but approximately ...

es in the family ''Quadriviridae'' have a non-enveloped isometric

capsid A capsid is the protein shell of a virus, enclosing its genetic material. It consists of several oligomeric (repeating) structural subunits made of protein called protomers. The observable 3-dimensional morphological subunits, which may or m ...

which consists of 60 copies of heterodimers of the structural proteins P2 and P4. The diameter of the capsid is around 48 nm.

Genome

Family member

genomes A genome is all the genetic information of an organism. It consists of nucleotide sequences of DNA (or RNA in RNA viruses). The nuclear genome includes protein-coding genes and non-coding genes, other functional regions of the genome such as ...

are composed of double-stranded RNA. They are divided in to four segments which each code for a protein. The length of the different segments are between 3.5 and 5.0 kbp. The total genome is around 16.8 kbp. Inside the capsid with the genome there is also the

RNA-dependent RNA polymerase RNA-dependent RNA polymerase (RdRp) or RNA replicase is an enzyme that catalyzes the self-replication, replication of RNA from an RNA template. Specifically, it catalyzes synthesis of the RNA strand Complementarity (molecular biology), compleme ...

Life cycle

Quadriviruses are transmitted internally. They are propagated during cell division and

hypha A hypha (; ) is a long, branching, filamentous structure of a fungus, oomycete, or actinobacterium. In most fungi, hyphae are the main mode of vegetative growth, and are collectively called a mycelium. Structure A hypha consists of one o ...

anastomosis An anastomosis (, : anastomoses) is a connection or opening between two things (especially cavities or passages) that are normally diverging or branching, such as between blood vessels, leaf veins, or streams. Such a connection may be normal (su ...

. Viral replication occurs in the

cytoplasm The cytoplasm describes all the material within a eukaryotic or prokaryotic cell, enclosed by the cell membrane, including the organelles and excluding the nucleus in eukaryotic cells. The material inside the nucleus of a eukaryotic cell a ...

. It follows the

double-stranded RNA virus Double-stranded RNA viruses (dsRNA viruses) are a polyphyletic group of viruses that have double-stranded genomes made of ribonucleic acid. The double-stranded genome is used as a template by the viral RNA dependent RNA polymerase (RdRp) to t ...

replication model. Double-stranded RNA virus transcription is the method of transcription. The fungi ''

'' serves as a natural host.

Taxonomy

The family ''Quadrivirdae'' has one genus ''Quadrivirus'', which contains the following species: * '' Quadrivirus ichi'' (Rosellinia necatrix quadrivirus 1) * '' Quadrivirus ni'' * '' Quadrivirus sani''

References

External links

ICTV Report: ''Quadriviridae''

{{Taxonbar, from=Q18811737 Virus families Riboviria