''Crinivirus'', formerly the ''lettuce infectious yellows virus group'', is a genus 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 bacteria and archaea. Since Dmitri Ivanovsky's 1 ...

, in the family ''

Closteroviridae ''Closteroviridae'' is a family of viruses. Plants serve as natural hosts. There are four genera and 59 species in this family, seven of which are unassigned to a genus. Diseases associated with this family include: yellowing and necrosis, parti ...

''. They are linear, single-stranded positive sense

RNA virus An RNA virus is a virusother than a retrovirusthat has ribonucleic acid (RNA) as its genetic material. The nucleic acid is usually single-stranded RNA ( ssRNA) but it may be double-stranded (dsRNA). Notable human diseases caused by RNA viruses ...

es (and are therefore

group IV The carbon group is a periodic table group consisting of carbon (C), silicon (Si), germanium (Ge), tin (Sn), lead (Pb), and flerovium (Fl). It lies within the p-block. In modern IUPAC notation, it is called group 14. In the field of semicond ...

). There are 14 species in this genus. Diseases associated with this genus include: yellowing and necrosis, particularly affecting the phloem. Examples of species whose entire

genome In the fields of molecular biology and genetics, a genome is all the genetic information of an organism. It consists of nucleotide sequences of DNA (or RNA in RNA viruses). The nuclear genome includes protein-coding genes and non-coding ge ...

s have been

sequenced In genetics and biochemistry, sequencing means to determine the primary structure (sometimes incorrectly called the primary sequence) of an unbranched biopolymer. Sequencing results in a symbolic linear depiction known as a sequence which suc ...

that are currently classified into the genus include the Sweet potato chlorotic stunt virus (SPCSV) and the Lettuce infectious yellows virus (LIYV).ICTVdB Management (2006)

Genetics

The viruses of this genus have segmented, bipartite genomes that add up to 7,500–19,500

nucleotide Nucleotides are organic molecules consisting of a nucleoside and a phosphate. They serve as monomeric units of the nucleic acid polymers – deoxyribonucleic acid (DNA) and ribonucleic acid (RNA), both of which are essential biomolecules wi ...

s in length. Their genomes also code for

protein Proteins are large biomolecules and macromolecules that comprise one or more long chains of amino acid residues. Proteins perform a vast array of functions within organisms, including catalysing metabolic reactions, DNA replication, respo ...

s that do not form part of the virion particles as well as structural proteins. The Universal Virus Database describes that their genome sequences near their 3'-ends are capable of hairpin-loop formation and also believe that their 5'-ends may have methylated caps. Each of the viral RNA molecules contains four hair-pin structures and a

pseudoknot __NOTOC__ A pseudoknot is a nucleic acid secondary structure containing at least two stem-loop structures in which half of one stem is intercalated between the two halves of another stem. The pseudoknot was first recognized in the turnip yellow ...

in the 3'UTR. The pseudoknot is unusual in that it contains a small

stem-loop Stem-loop intramolecular base pairing is a pattern that can occur in single-stranded RNA. The structure is also known as a hairpin or hairpin loop. It occurs when two regions of the same strand, usually complementary in nucleotide sequence when ...

structure inside loop L1. In the related genus Closterovirus, these secondary structures have been found to be important in viral RNA replication.

Structure

Viruses in the genus ''Crinivirus'' are non-enveloped, with bipartite filamentous geometries. The diameter is around 10-13 nm, with a length of 700-900 nm. Genomes are linear and bipartite, around 17.6kb in length.

Life cycle

Viral replication is cytoplasmic. 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 tubule-guided viral movement. Plants serve as the natural host. The virus is transmitted via a vector (bemisia tabaci). Transmission route is mechanical.

Taxonomy

The following species are assigned to the genus: *'' Abutilon yellows virus'' *'' Bean yellow disorder virus'' *''

Beet pseudoyellows virus ''Beet pseudoyellows virus'' (BPYV) is a species of virus in the genus '' Crinivirus''. The virus was first recognised by James E. Duffus of the United States Department of Agriculture, and reported in 1975 under the title 'A new type of whitefl ...

'' *'' Blackberry yellow vein-associated virus'' *'' Cucurbit yellow stunting disorder virus'' *'' Diodia vein chlorosis virus'' *'' Lettuce chlorosis virus'' *'' Lettuce infectious yellows virus'' *'' Potato yellow vein virus'' *'' Strawberry pallidosis-associated virus'' *'' Sweet potato chlorotic stunt virus'' *'' Tetterwort vein chlorosis virus'' *'' Tomato chlorosis virus'' *'' Tomato infectious chlorosis virus''

References

External links

ICTV Report: ''Closteroviridae''

Rfam entry for 3'-terminal pseudoknot in SPCSV

Rfam entry for 3'-terminal pseudoknot of CuYV/BPYV

Rfam entry for 3'-terminal pseudoknot in PYVV
{{Taxonbar, from=Q3002668 Closteroviridae Viral plant pathogens and diseases Virus genera