Human picobirnavirus
| Picobirnavirus | |
|---|---|
| Virus classification | |
| Group: | Group III (dsRNA) |
| Family: | Picobirnaviridae |
| Genus: | Picobirnavirus |
| Type Species | |
Picobirnavirus is a genus of dsRNA viruses, the only genus in the family Picobirnaviridae. Amniotes, especially mammals, serve as natural hosts. There are currently only two species in this genus including the type species Human picobirnavirus. Diseases associated with this genus include: gastroenteritis in animals and humans, but the disease association is unclear.
First detection of Picobirnavirus (PBV) was in humans and black-footed pigmy rice rats in 1988.
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. Mammals serve as the natural host. Transmission routes are fecal-oral.
Viruses in Picobirnavirus are non-enveloped, with icosahedral geometries, and T=3 symmetry. The diameter is around 35-40 nm.
The genome is linear, bipartate, and double stranded RNA. It includes a segment 1 – 2.5 (2.2–2.7) kilobases (kb) length and a segment 2 – 1.7 (1.2–1.9) kb in length. The genome codes for 3 to 4 proteins. The capsid protein gene is encoded by the second open reading frame of the larger genomic segment.
These viruses are divided into two genogroups on the basis of the sequence of segment 2.
They have been isolated from humans and other mammals, as well as birds and squamates. Their role in pathogenicity if any is not yet clear.
PBV was initially thought to belong to family Birnaviridae but later confirmed to differ with respect to host, virion size, capsid, RNA polymerase, genome size, and organization. Now PBV has been classified distinctly A new viral family named Picobirnaviridae under the proposed order Diplornavirales was created to accommodate this unique virus and a complete new taxonomic order was assigned [1]. This new viral family is composed of only one viral genus, Picobirnavirus. The two species under the genus are Human Picobirnavirus and Rabbit Picobirnavirus, where the former one is nominated as a type species and the latter one was designated species by the International Committee on Taxonomy of Viruses in 2008. The nomenclature of the virus has been derived from its size and genome characteristics: the prefix “pico” signifies the small diameter of the viral particle (35 nm) and “birna” signposts a genome composed of two segments of dsRNA.
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