Carlavirus

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 currently 53 species in this genus including the type species Carnation latent virus. Diseases associated with this genus include: mosaic and ringspot symptoms.[1][2]

Carlavirus
Virus classification
(unranked): Virus
Realm: Riboviria
Kingdom: Orthornavirae
Phylum: Kitrinoviricota
Class: Alsuviricetes
Order: Tymovirales
Family: Betaflexiviridae
Subfamily: Quinvirinae
Genus: Carlavirus
Type species
Carnation latent virus
Species

See text

Synonyms

Carnation latent virus group

Description

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.

Taxonomy

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] The current position in the 9th report (2009) as a genus of the family Betaflexiviridae derives from the subsequent subdivision of Flexiviridae.

Group: ssRNA(+)

[2]

Virology

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.

Life cycle

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]

GenusHost detailsTissue tropismEntry detailsRelease detailsReplication siteAssembly siteTransmission
CarlavirusPlantsNoneViral movement; mechanical inoculationViral movementCytoplasmCytoplasmMechanical: insects

Transmission

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.[5] 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)

References
  1. "Viral Zone". ExPASy. Retrieved 15 June 2015.
  2. ICTV. "Virus Taxonomy: 2014 Release". Retrieved 15 June 2015.
  3. King 2012.
  4. Adams, M. J.; Antoniw, J. F.; Bar-Joseph, M.; Brunt, A. A.; Candresse, T.; Foster, G. D.; Martelli, G. P.; Milne, R. G.; Fauquet, C. M. (2 May 2004). "Virology Division News: The new plant virus family Flexiviridae and assessment of molecular criteria for species demarcation". Archives of Virology. 149 (5): 1045–60. doi:10.1007/s00705-004-0304-0. PMID 15098118. S2CID 34493607.
  5. Astier S. Principles of Plant Virology p78

Bibliography
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