Partitiviridae is a family of double-stranded RNA viruses.[2]Plants, fungi, and protozoa serve as natural hosts. It has been suggested that they can also infect bacteria.[3] 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.[4][5]
Structure
Penicillium stoloniferum virus F (PsV-F), Gammapartititvirus, and PsV-F CPdimer
Viruses in the family Partitiviridae are non-enveloped with icosahedral geometries and T=1 symmetry.[6] The diameter of partitiviruses is around 25–43 nm.[4]
Genome
Genome of atkinsonella hypoxylon virus (AhV) of genus Betapartitivirus
Partitiviruses have double-stranded RNA genomes divided into two genomic segments, and there may be additional subgenomic segments. The two genome 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.[4][6]
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.[4][6] Cryspoviruses infect apicomplexian protozoa of the genus Cryptosporidium,[7] while viruses of the other genera infect plants and fungi. It has been suggested that they can also infect bacteria.
Genus
Host details
Tissue tropism
Entry details
Release details
Replication site
Assembly site
Transmission
Cryspovirus
Protists
None
Cell division; sporogenesis; hyphal anastomosis
Cell division; sporogenesis; hyphal anastomosis
Cytoplasm
Cytoplasm
Cell division; sporogenesis; hyphal anastomosis
Alphapartitivirus
None
Cytoplasm
Cytoplasm
Cell division
Deltapartitivirus
Plants
None
Viral movement; mechanical inoculation
Cell division
Cytoplasm
Cytoplasm
Cell division
Betapartitivirus
None
Cytoplasm
Cytoplasm
Cell division
Gammapartitivirus
Fungi
None
Cytoplasmic exchange; hyphal anastomosis
Cytoplasmic exchange; hyphal anastomosis
Cytoplasm
Cytoplasm
Cytoplasmic exchange; hyphal anastomosis
Phylogenetics
Based on the RNA polymerase gene this group can be divided into four clades (I-IV).[8] Four isolates from animals and protozoans form a fifth clade. Clades I–IV consist of mixtures of partitivirus-like sequences from plants and fungi.[citation needed]
Taxonomy
Phylogenetic tree of Partitiviridae
There are five recognized genera within the Partitiviridae family. There are an additional fifteen species in the family unassigned to a genus:[4][5]
^Neri U, Wolf YI, Roux S, Camargo AP, Kazlauskas D, Min Chen I, Lee B, Ivanova N, Allen LZ, Paez-Espino D, Bryant DA, Bhaya D, Krupovic M, Dolja VV, Kyrpides NC, Koonin EV, Gophna U (17 February 2022). "A five-fold expansion of the global RNA virome reveals multiple new clades of RNA bacteriophages". bioRxiv10.1101/2022.02.15.480533.
^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
^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.
