''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. Viruses are found in almo ...
, in the family ''
Closteroviridae
''Closteroviridae'' is a family of viruses. Plants serve as natural hosts. There are seven genera in this family. Diseases associated with this family include: yellowing and necrosis, particularly affecting the phloem.
Taxonomy
Genome type and ...
''.
They are linear, single-stranded positive sense
RNA virus
An RNA virus is a virus characterized by a ribonucleic acid (RNA) based genome. The genome can be single-stranded RNA (ssRNA) or double-stranded (Double-stranded RNA, dsRNA). Notable human diseases caused by RNA viruses include influenza, SARS, ...
es (and are therefore
group IV). There are 14 species in this genus.
[ Diseases associated with this genus include: yellowing and necrosis, particularly affecting the phloem.]genome
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 genes, other functional regions of the genome such as ...
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 succi ...
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 compound, organic molecules composed of a nitrogenous base, a pentose sugar and a phosphate. They serve as monomeric units of the nucleic acid polymers – deoxyribonucleic acid (DNA) and ribonucleic acid (RNA), both o ...
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 residue (biochemistry), residues. Proteins perform a vast array of functions within organisms, including Enzyme catalysis, catalysing metab ...
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.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-loops are nucleic acid Biomolecular structure, secondary structural elements which form via intramolecular base pairing in single-stranded DNA or RNA. They are also referred to as hairpins or hairpin loops. A stem-loop occurs when two regi ...
structure inside loop L1.Closterovirus
''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 ...
, 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, listed by scientific name and followed by their common names:
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