''Partitiviridae'' is a family of

double-stranded RNA viruses Double-stranded RNA viruses (dsRNA viruses) are a Polyphyly, polyphyletic group of viruses that have Nucleic acid double helix, double-stranded genomes made of ribonucleic acid. The double-stranded genome is used to transcribe a Sense (molecular ...

Plants Plants are predominantly photosynthetic eukaryotes of the kingdom Plantae. Historically, the plant kingdom encompassed all living things that were not animals, and included algae and fungi; however, all current definitions of Plantae exclude ...

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

, and protozoa serve as natural hosts. It has been suggested that they can also infect

bacteria Bacteria (; singular: bacterium) are ubiquitous, mostly free-living organisms often consisting of one Cell (biology), biological cell. They constitute a large domain (biology), domain of prokaryotic microorganisms. Typically a few micrometr ...

. The name comes from the Latin ''partitius,'' which means divided, and refers to the segmented genome of partitiviruses. There are five genera and 60 species in the family, 15 of which are unassigned to a genus.

Structure

Viruses in the family ''Partitiviridae'' are non-enveloped with icosahedral geometries and T=1 symmetry. The diameter of partitiviruses is around 25–43 nm.

Genome

Partitiviruses have double-stranded RNA genomes divided into two genomic segments, and there may be additional subgenomic segments. The two

genome In the fields of molecular biology and genetics, 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 g ...

segments are packaged in separate virus particles. They code for two separate proteins. The first segment codes for the RNA-dependent RNA polymerase (RdRp), and the second segment codes for the coat protein. The segments are around 1.4–3.0 kbp in length, while the total genome length is around 3.0–4.8 kbp.

Life cycle

Viral replication is cytoplasmic. Entry into the host cell is achieved by penetration into the host cell. 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 and plants serve as the natural host. Cryspoviruses infect apicomplexian protozoa of the genus '' Cryptosporidium'',Nibert ML, Woods KM, Upton SJ, Ghabrial SA (2009) Cryspovirus: a new genus of protozoan viruses in the family Partitiviridae. Arch Virol 154(12):1959–1965 while viruses of the other genera infect plants and fungi. It has been suggested that they can also infect bacteria.

Phylogenetics

Based on the RNA polymerase gene this group can be divided into four clades (I-IV).Liu H, Fu Y, Xie J, Cheng J, Ghabrial SA, Li G, Yi X, Jiang D (2012) Discovery of Novel dsRNA Viral Sequences by In Silico Cloning and Implications for Viral Diversity, Host Range and Evolution. PLoS One. 2012;7(7):e42147. Four isolates from animals and protozoans form a fifth clade. Clades I–IV consist of mixtures of partitivirus-like sequences from plants and fungi.

Taxonomy

References

External links

ICTV Online Report: ''Partitivirdae''

{{Taxonbar, from=Q3772877 Virus families Riboviria