| Pospiviroid | |
|---|---|
Virus classification  | |
| (unranked): | Virus |
| Realm: | incertae sedis |
| Kingdom: | incertae sedis |
| Phylum: | incertae sedis |
| Class: | incertae sedis |
| Order: | incertae sedis |
| Family: | Pospiviroidae |
| Genus: | Pospiviroid |
| Species | |
Chrysanthemum stunt viroid | |
Pospiviroid is a genus of viroids that most commonly infects tubers. It belongs to the family Pospiviroidae . [1] The first viroid discovered was a pospiviroid, the PSTVd species (potato spindle tuber viroid).
Viroids are the smallest infectious pathogens known. They are composed solely of a short strand of circular, single-stranded RNA that has no protein coating. All known viroids are inhabitants of angiosperms, and most cause diseases, whose respective economic importance on humans varies widely.
Virus classification is the process of naming viruses and placing them into a taxonomic system similar to the classification systems used for cellular organisms.
Hepatitis D is a type of viral hepatitis caused by the hepatitis delta virus (HDV), a small spherical enveloped particle that shares similarities with both a viroid and virusoid. HDV is one of five known hepatitis viruses: A, B, C, D, and E. HDV is considered to be a satellite because it can propagate only in the presence of the hepatitis B virus (HBV). Transmission of HDV can occur either via simultaneous infection with HBV (coinfection) or superimposed on chronic hepatitis B or hepatitis B carrier state (superinfection).
Virusoids are circular single-stranded RNA(s) dependent on viruses for replication and encapsidation. The genome of virusoids consist of several hundred (200–400) nucleotides and does not code for any proteins.
A satellite is a subviral agent that depends on the coinfection of a host cell with a helper virus for its replication. Satellites can be divided into two major classes: satellite viruses and satellite nucleic acids. Satellite viruses, which are most commonly associated with plants, but are also found in mammals, arthropods, and bacteria, encode structural proteins to enclose their genetic material, which are therefore distinct from the structural proteins of their helper viruses. Satellite nucleic acids, in contrast, do not encode their own structural proteins, but instead are encapsulated by proteins encoded by their helper viruses. The genomes of satellites range upward from 359 nucleotides in length for satellite tobacco ringspot virus RNA (STobRV).
Theodor Otto Diener is a Swiss-American plant pathologist. In 1971, he discovered that the causative agent of the potato spindle tuber disease is not a virus, but a novel agent, which consists solely of a short strand of single-stranded RNA without a protein capsid, eighty times smaller than the smallest viruses. He proposed to name it, and similar agents yet to be discovered, viroids. Viroids displaced viruses as the smallest known infectious agents.
The Potato spindle tuber viroid ("PSTVd") was the first viroid to be identified. PSTVd is a small, single stranded circular RNA molecule closely related to the chrysanthemum stunt viroid. Present within the viroidal RNA is the Pospiviroid RY motif stem loop. The natural hosts are potatoes and tomatoes. All potatoes and tomatoes are susceptible to PSTVd and there is no form of natural resistance. Natural infections have also been seen in avocados and infections in other solanaceous crops have been induced in the laboratory. Until 2017 PSTVd was thought to be unable to infect Solanum sisymbriifolium. Then in May seeds exported by a Dutch company were noticed to be infected. These seeds were shipped from the company, but had been originally bred to their specifications in two Asian countries.
The Pospiviroidae are a family of viroids, including the first viroid to be discovered, PSTVd. Their secondary structure is key to their biological activity. The classification of this family is based on differences in the conserved central region sequence. The genome consists of an LH terminal domain, a pathogenic domain, conserved central region, variable domain, and an RH terminal domain. Pospiviroidae replication occurs in an asymmetric fashion via host cell RNA polymerase, RNase, and RNA ligase.
PSTV may refer to:
Rolling circle replication (RCA) is a process of unidirectional nucleic acid replication that can rapidly synthesize multiple copies of circular molecules of DNA or RNA, such as plasmids, the genomes of bacteriophages, and the circular RNA genome of viroids. Some eukaryotic viruses also replicate their DNA or RNA via the rolling circle mechanism.
The International Committee on Taxonomy of Viruses (ICTV) authorizes and organizes the taxonomic classification of and the nomenclatures for viruses. The ICTV has developed a universal taxonomic scheme for viruses, and thus has the means to appropriately describe, name, and classify every virus that affects living organisms. The members of the International Committee on Taxonomy of Viruses are considered expert virologists. The ICTV was formed from and is governed by the Virology Division of the International Union of Microbiological Societies. Detailed work, such as delimiting the boundaries of species within a family, typically is performed by study groups of experts in the families.
Avocado sunblotch viroid (ASBV) is a disease affecting avocado trees.
Non-cellular life, or acellular life is life that exists without a cellular structure for at least part of its life cycle. Historically, most (descriptive) definitions of life postulated that a living organism must be composed of one or more cells, but this is no longer considered necessary, and modern criteria allow for forms of life based on other structural arrangements.
Peach latent mosaic viroid is the type species of the genus Pelamoviroid, which belongs to the family Avsunviroidae. This family is characterized as having chloroplastic viroids with hammerhead ribozymes. Peach latent mosaic viroid is a 336-351nt circular RNA which has a branched formation. This branched formation is stabilised by a pseudoknot between two kissing loops. Peach latent mosaic viroid was first described in the 1980s in Spain by a group of scientists.
The Avsunviroidae are a family of viroids. There are four species in three genera. They consist of RNA genomes between 246–375 nucleotides in length. They are single-stranded covalent circles and have intramolecular base pairing. All members lack a central conserved region.
The Pospiviroid RY motif stem loop is an RNA element found in Pospiviroids such as potato spindle tuber viroid (PSTVd). The RY nucleotide sequence motif in PSTVd, is thought to bind with the tomato protein Virp1. The exact function of this motif and the significance of Virp1 binding is unknown. It is however thought that RY motifs are essential for establishing a viroid infection.
The hop stunt viroid is a viroid species that infects the common hop plant, citrus plants and grapevines, among others. It is a member of the Pospiviroidae family and the Hostuviroid genus. There are quite a few different sub-species of the hop stunt viroid.
Hostuviroid is a genus of viroids that includes Hop stunt viroid, a species of viroids that infects many different types of plants, including the common hop plant.
Cadang-cadang is a disease caused by Coconut cadang-cadang viroid (CCCVd), a lethal viroid of coconut, African oil palm, anahaw, and buri palms. The name cadang-cadang comes from the word gadang-gadang that means dying in Bicol. It was originally reported on San Miguel Island in the Philippines in 1927/1928. "By 1962, all but 100 of 250,000 palms on this island had died from the disease," indicating an epidemic. Every year one million coconut palms are killed by CCCVd and over 30 million coconut palms have been killed since Cadang-cadang was discovered. CCCVd directly affects the production of copra, a raw material for coconut oil and animal feed. Total losses of about 30 million palms and annual yield losses of about 22,000 tons of copra have been attributed to Cadang-cadang disease in the Philippines.
In virology, realm is the highest taxonomic rank established for viruses by the International Committee on Taxonomy of Viruses (ICTV), which oversees virus taxonomy. Four virus realms are recognized and united by specific highly conserved traits: Duplodnaviria, which contains all double-stranded DNA (dsDNA) viruses that encode the HK97-fold major capsid protein; Monodnaviria, which contains all single-stranded DNA (ssDNA) viruses that encode a HUH superfamily endonuclease and their descendents; Riboviria, which contains all RNA viruses that encode RNA-dependent RNA polymerase and all viruses that encode reverse transcriptase; and Varidnaviria, which contains all dsDNA viruses that encode a vertical jelly roll major capsid protein.
 | This virus-related article is a stub. You can help Wikipedia by expanding it. |