Picobirnavirus | |
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Electron micrograph of human picobirnavirus particles | |
Virus classification | |
(unranked): | Virus |
Realm: | Riboviria |
Kingdom: | Orthornavirae |
Phylum: | Pisuviricota |
Class: | Duplopiviricetes |
Order: | Durnavirales |
Family: | Picobirnaviridae |
Genus: | Picobirnavirus |
Picobirnavirus is a genus of double-stranded RNA viruses. It is the only genus in the family Picobirnaviridae. [1] Although amniotes, especially mammals, were thought to serve as hosts, it has been recently suggested that these viruses might infect bacteria and possibly some other invertebrates. If they do infect bacteria, then they are Bacteriophages. [2] [3] There are three species in this genus. Associated symptoms include gastroenteritis in animals and humans, though the disease association is unclear. [4] [5]
Picobirnavirus is a small (pico, Spanish for small), bisegmented (bi, Latin for two), double-stranded RNA virus. Picobirnaviruses were initially considered to be birna-like viruses, and the name was derived from birnavirus (bisegmented RNA), but the virions are much smaller (diameter 35 nm vs. 65 nm). [6] Picobirnaviruses were first detected in humans and black-footed pigmy rice rats in 1988. [7]
Viruses in the genus are non-enveloped, with icosahedral geometries, and T=3 symmetry. The diameter is around 35–40 nm. [5] [4]
The genome is linear, bipartite, and composed of double-stranded RNA. It includes a segment 1 which is 2.2–2.7 kilobases (kb) in length and a segment 2 which is 1.2–1.9 kb in length. The genome codes for three to four proteins. [4] The capsid protein gene is encoded by the second open reading frame of the larger genomic segment 1. [4]
Picobirnaviruses are divided into two genogroups on the basis of the sequence of segment 2. The RNA-dependent RNA polymerase (RdRp) is encoded by segment 2. The group viruses have been isolated from humans and other mammals, as well as birds and squamates. [8]
Picobirnaviruses target intestine tissue. Entry into the host cell is achieved by penetration into the host cell. Once in the host cell, viral replication is cytoplasmic. Replication follows the double-stranded RNA virus replication model. Double-stranded RNA virus transcription is the method of transcription. The viruses are released from the cell by budding. Mammals serve as the natural host. Transmission routes are fecal-oral. [5] [4]
Picobirnaviruses were initially thought to belong to the family Birnaviridae , but later were confirmed to differ with respect to host, virion size, capsid, RNA-dependent RNA polymerase, genome size, and organization. [9] The family Picobirnaviridae is now classified distinctly and composed of one genus Picobirnavirus, which has three species: [10]
Hepadnaviridae is a family of viruses. Humans, apes, and birds serve as natural hosts. There are currently 18 species in this family, divided among 5 genera. Its best-known member is hepatitis B virus. Diseases associated with this family include: liver infections, such as hepatitis, hepatocellular carcinomas, and cirrhosis. It is the sole accepted family in the order Blubervirales.
Rubella virus (RuV) is the pathogenic agent of the disease rubella, transmitted only between humans via the respiratory route, and is the main cause of congenital rubella syndrome when infection occurs during the first weeks of pregnancy.
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Geminiviridae is a family of plant viruses that encode their genetic information on a circular genome of single-stranded (ss) DNA. There are 520 species in this family, assigned to 14 genera. Diseases associated with this family include: bright yellow mosaic, yellow mosaic, yellow mottle, leaf curling, stunting, streaks, reduced yields. They have single-stranded circular DNA genomes encoding genes that diverge in both directions from a virion strand origin of replication. According to the Baltimore classification they are considered class II viruses. It is the largest known family of single stranded DNA viruses.
Cystovirus is a genus of double-stranded RNA viruses which infects bacteria. It is the only genus in the family Cystoviridae. The name of the group cysto derives from Greek kystis which means bladder or sack. There are seven species in this genus.
Pseudoviridae is a family of viruses, which includes three genera.
Potyviridae is a family of positive-strand RNA viruses that encompasses more than 30% of known plant viruses, many of which are of great agricultural significance. The family has 12 genera and 235 species, three of which are unassigned to a genus.
Kobuvirus is a genus of viruses in the order Picornavirales, in the family Picornaviridae. Humans and cattle serve as natural hosts. There are six species in this genus. Diseases associated with this genus include: gastroenteritis. The genus was named because of the virus particles' lumpy appearance by electron microscopy; "kobu" means "knob" in Japanese.
Erbovirus is a genus of viruses in the order Picornavirales, in the family Picornaviridae. Horses serve as natural hosts. There is only one species in this genus: Erbovirus A. Diseases associated with this genus include: upper respiratory tract disease with viremia and fecal shedding. Viruses belonging to the genus Erbovirus have been isolated in horses with acute upper febrile respiratory disease. The structure of the Erbovirus virion is icosahedral, having a diameter of 27–30 nm.
Gyrovirus is a genus of viruses, in the family Anelloviridae. Until 2011, chicken anemia virus was the only Gyrovirus identified, but since then gyroviruses have also been identified in humans. Diseases associated with this genus include: chicken infectious anemia, which is associated with depletion of cortical thymocytes and erythroblastoid cells.
Corticovirus is a genus of viruses in the family Corticoviridae. Corticoviruses are bacteriophages; that is, their natural hosts are bacteria. The genus contains two species. The name is derived from Latin cortex, corticis. However, prophages closely related to PM2 are abundant in the genomes of aquatic bacteria, suggesting that the ecological importance of corticoviruses might be underestimated. Bacteriophage PM2 was first described in 1968 after isolation from seawater sampled from the coast of Chile.
Vesivirus is a genus of viruses, in the family Caliciviridae. Swine, sea mammals, and felines serve as natural hosts. There are two species in this genus. Diseases associated with this genus include: respiratory disease, Feline calicivirus (FCV); conjunctivitis, and respiratory disease.
Lagovirus is a genus of viruses, in the family Caliciviridae. Lagomorphs serve as natural hosts. There are two species in this genus. Diseases associated with this genus include: necrotizing hepatitis leading to fatal hemorrhages.
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Virgaviridae is a family of positive-strand RNA viruses. Plants serve as natural hosts. The name of the family is derived from the Latin word virga (rod), as all viruses in this family are rod-shaped. There are currently 59 species in this family, divided among seven genera.
Yingchengvirus is a genus of double stranded DNA viruses that infect haloarchaea. The genus was previously named Betasphaerolipovirus.
Avibirnavirus is a genus of viruses in family Birnaviridae. There is a single species in this genus: Infectious bursal disease virus, which infects chickens and other fowl. It causes severe inflammation of the bursa of Fabricius, and causes considerable morbidity and mortality.
Entomobirnavirus is a genus of viruses in the family Birnaviridae. Its natural host is the fly Drosophila melanogaster. There are two species in this genus.
Quadriviridae is a family of double-stranded RNA viruses with a single genus Quadrivirus. The fungi Rosellinia necatrix serves as a natural host. The name of the group derives from the quadripartite genome of its members where in Latin quad means four. There is only one species in this family: Rosellinia necatrix quadrivirus 1.
Bacilladnaviridae is a family of single-stranded DNA viruses that primarily infect diatoms.