Carnation latent virus
Carnation latent virus (CLV) is a plant pathogenic virus of the family ''Betaflexiviridae''.
External linksICTVdB - The Universal Virus Database: Carnation latent virusvirus
A virus is a submicroscopic infectious agent that replicates only inside the living Cell (biology), cells of an organism. Viruses infect all life forms, from animals and plants to microorganisms, including bacteria and archaea. Viruses are ...
es in the order ''
Tymovirales
''Tymovirales'' is an order of viruses with five families. The group consists of viruses which have positive-sense, single-stranded RNA genomes. Their genetic material is protected by a special coat protein.
Description
Tymoviruses are mainly ...
'', in the family ''
Betaflexiviridae
''Betaflexiviridae'' is a family of viruses
A virus is a submicroscopic infectious agent that replicates only inside the living cells of an organism. Viruses infect all life forms, from animals and plants to microorganisms, including ...
''. Plants serve as natural hosts. There are 74 species in this genus. Diseases associated with this genus include: mosaic and ringspot symptoms.
Description
''Carlavirus'' is described in the 9th report of the ICTV (2009). The genus is characterised by having six ORFs (
open reading frame
In molecular biology, reading frames are defined as spans of DNA sequence between the start and stop codons. Usually, this is considered within a studied region of a prokaryotic DNA sequence, where only one of the six possible reading frames ...
s) including a TGB (
Triple Gene Block
Triple is used in several contexts to mean "threefold" or a " treble":
Sports
* Triple (baseball), a three-base hit
* A basketball three-point field goal
* A figure skating jump with three rotations
* In bowling terms, three strikes in a row
* I ...
). 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
''Flexiviridae'' was a family of viruses named after being filamentous and highly flexible. Members of the family infect plants. In 2009, the family was dissolved and replaced with four families, each of which still contain the name ''flexiviridae ...
Passiflora latent virus
''Passiflora'', known also as the passion flowers or passion vines, is a genus of about 550 species of flowering plants, the type genus of the family Passifloraceae.
''Passiflora'' species are widely cultivated for their striking flowers, flav ...
Helleborus net necrosis virus
Commonly known as hellebores (), the Eurasian genus ''Helleborus'' consists of approximately 20 species of herbaceous or evergreen perennial flowering plants in the family Ranunculaceae, within which it gave its name to the tribe of Helleboreae ...
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
RNA-dependent RNA polymerase (RdRp) or RNA replicase is an enzyme that catalyzes the self-replication, replication of RNA from an RNA template. Specifically, it catalyzes synthesis of the RNA strand Complementarity (molecular biology), compleme ...
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.
Transmission
Infection is at times spread by
aphid
Aphids are small sap-sucking insects in the Taxonomic rank, family Aphididae. Common names include greenfly and blackfly, although individuals within a species can vary widely in color. The group includes the fluffy white Eriosomatinae, woolly ...
s in a semi-persistent mode, that is, the vector is infective for a number of hours.(Pimentel) Some species are transmitted by ''
Bemisia tabaci
The silverleaf whitefly (''Bemisia tabaci'', also informally referred to as the sweet potato whitefly) is one of several species of whitefly that are currently important agricultural pests. A review in 2011 concluded that the silverleaf whitefly ...
'' in a semi-persistent mode or through the seed.Astier S. Principles of Plant Virology p78 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)