Carlavirus | |
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Virus classification | |
(unranked): | Virus |
Realm: | Riboviria |
Kingdom: | Orthornavirae |
Phylum: | Kitrinoviricota |
Class: | Alsuviricetes |
Order: | Tymovirales |
Family: | Betaflexiviridae |
Subfamily: | Quinvirinae |
Genus: | Carlavirus |
Species | |
See text | |
Synonyms | |
Carnation latent virus group |
Carlavirus, formerly known as the "Carnation latent virus group", is a genus of viruses in the order Tymovirales , in the family Betaflexiviridae . Plants serve as natural hosts. There are 53 species in this genus. Diseases associated with this genus include: mosaic and ringspot symptoms. [1] [2]
Carlavirus is described in the 9th report of the ICTV (2009). [3] The genus is characterised by having six ORFs (open reading frames) including a TGB (Triple Gene Block). The viruses are transmitted by insects.
The genus was first proposed in the first report of the ICTV in 1971, as the 'Carnation latent virus group' but was renamed in 1975 as the 'Carlavirus group', and as the genus Carlavirus in 1995 (6th report). In 2005 (8th report) it was placed in the Flexiviridae family, having previously been unassigned. [4] [5] The current position in the 9th report (2009) as a genus of the family Betaflexiviridae derives from the subsequent subdivision of Flexiviridae. [5]
The following species are assigned to the genus: [2]
The virions are non enveloped, filamentous, 610–700 nanometers (nm) and 12–15 nm in diameter.
The linear 5.8–9 kilobase genome is positive sense, single-stranded RNA. The 3’ terminus is polyadenylated. In some species the 5’ end is capped. The genome encodes 3 to 6 proteins including a coat protein located at the 3' end and an RNA-dependent RNA polymerase located at the 5' end of the genome.
Viral replication is cytoplasmic, and is lysogenic. Entry into the host cell is achieved by penetration into the host cell. Replication follows the positive stranded RNA virus replication model. Positive stranded RNA virus transcription is the method of transcription. The virus exits the host cell by tripartite non-tubule guided viral movement. Plants serve as the natural host. [1]
Genus | Host details | Tissue tropism | Entry details | Release details | Replication site | Assembly site | Transmission |
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Carlavirus | Plants | None | Viral movement; mechanical inoculation | Viral movement | Cytoplasm | Cytoplasm | Mechanical: insects |
Infection is at times spread by aphids in a semi-persistent mode, that is, the vector is infective for a number of hours.(Pimentel) Some species are transmitted by Bemisia tabaci in a semi-persistent mode or through the seed. [6] Most species infect only a few hosts and cause infections with few or no symptoms, for example, American hop latent virus and lily symptomless virus. Some, such as blueberry scorch virus and poplar mosaic virus, cause serious illnesses. (Foster)
Viroids are small single-stranded, circular RNAs that are infectious pathogens. Unlike viruses, they have no protein coating. All known viroids are inhabitants of angiosperms, and most cause diseases, whose respective economic importance to humans varies widely. A recent metatranscriptomics study suggests that the host diversity of viroids and other viroid-like elements is broader than previously thought and that it would not be limited to plants, encompassing even the prokaryotes.
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, are also found in mammals, arthropods, and bacteria. They 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).
Tobamovirus is a genus of positive-strand RNA viruses in the family Virgaviridae. Many plants, including tobacco, potato, tomato, and squash, serve as natural hosts. Diseases associated with this genus include: necrotic lesions on leaves. The name Tobamovirus comes from the host and symptoms of the first virus discovered.
Potyvirus is a genus of positive-strand RNA viruses in the family Potyviridae. Plants serve as natural hosts. Like begomoviruses, members of this genus may cause significant losses in agricultural, pastoral, horticultural, and ornamental crops. More than 200 species of aphids spread potyviruses, and most are from the subfamily Aphidinae. The genus contains 190 species and potyviruses account for about thirty percent of all currently known plant viruses.
Closterovirus, also known as beet yellows viral group, is a genus of viruses, in the family Closteroviridae. Plants serve as natural hosts. There are 17 species in this genus. Diseases associated with this genus include: yellowing and necrosis, particularly affecting the phloem. This genus has a probably worldwide distribution and includes among other viral species the Beet yellows virus and Citrus tristeza virus, rather economically important plant diseases. At least some species require vectors such as aphids or mealybugs for their transmission from plant to plant.
Crinivirus, formerly the lettuce infectious yellows virus group, is a genus of viruses, in the family Closteroviridae. They are linear, single-stranded positive sense RNA viruses. There are 14 species in this genus. Diseases associated with this genus include: yellowing and necrosis, particularly affecting the phloem.
Nepovirus is a genus of viruses in the order Picornavirales, in the family Secoviridae, in the subfamily Comovirinae. Plants serve as natural hosts. There are 40 species in this genus. Nepoviruses, unlike the other two genera in the subfamily Comovirinae, are transmitted by nematodes.
Ilarvirus is a genus of positive-strand RNA viruses in the family Bromoviridae. Plants serve as natural hosts. There are 22 species in this genus.
Sobemovirus is a genus of non-enveloped, positive-strand RNA viruses which infect plants. Plants serve as natural hosts. There are 21 species in this genus. Diseases associated with this genus include: mosaics and mottles.
Potexvirus is a genus of pathogenic viruses in the order Tymovirales, in the family Alphaflexiviridae. Plants serve as natural hosts. There are 48 species in this genus, three of which are assigned to a subgenus. Diseases associated with this genus include: mosaic and ringspot symptoms. The genus name comes from POTato virus X).
Trichovirus is a genus of viruses in the order Tymovirales, in the family Betaflexiviridae. Plants, specifically angiosperms such as pome fruits, citrus, and pear, serve as natural hosts for this plant pathogen. There are seven species in this genus.
Betaflexiviridae is a family of viruses in the order Tymovirales. Plants and fungi serve as natural hosts. There are 108 species in this family, assigned to 13 genera in two subfamilies. Diseases associated with this family include mosaic and ringspot symptoms.
Emaravirus is a genus of negative-strand RNA viruses which infect plants. The plant virus group is the sole genus in the family Fimoviridae. The genus has 21 species.
Allexivirus is a genus of viruses in the order Tymovirales, in the family Alphaflexiviridae. Shallot, onion, and garlic serve as natural hosts. There are 13 species in this genus, seven of which are assigned to a subgenus. Diseases associated with this genus include: mosaic and ringspot symptoms.
Badnavirus is a genus of viruses, in the family Caulimoviridae order Ortervirales. Plants serve as natural hosts. There are 67 species in this genus. Diseases associated with this genus include: CSSV: leaf chlorosis, root necrosis, red vein banding in young leaves, small mottled pods, and stem/root swelling followed by die-back. Infection decreases yield by 25% within one year, 50% within two years and usually kills trees within 3–4 years.
Bromovirus is a genus of viruses, in the family Bromoviridae. Plants serve as natural hosts. There are six species in this genus.
Foveavirus is a genus of viruses in the order Tymovirales, in the family Betaflexiviridae. Plants serve as natural hosts. There are eight species in this genus. Diseases associated with this genus include: mosaic and ringspot symptoms.
Mastrevirus is a genus of ssDNA viruses, in the family Geminiviridae. Mostly monocotyledonous plants serve as natural hosts. They are vectored by planthoppers. There are 45 species in this genus. Diseases associated with this genus include: maize streak virus: maize streak disease (MSD).
Tymovirus is a genus of viruses in the order Tymovirales, in the family Tymoviridae. Plants serve as natural hosts. There are 28 species in this genus.
Alphanecrovirus is a genus of viruses, in the family Tombusviridae. Plants serve as natural hosts. There are four species in this genus.