Crinivirus
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 (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. Examples of species whose entire genomes have been sequenced that are currently classified into the genus include the Sweet potato chlorotic stunt virus (SPCSV) and the Lettuce infectious yellows virus (LIYV). Genetics. The viruses of this genus have segmented, bipartite genomes that add up to 7,500–19,500 nucleotides in  length. Their genomes also code for proteins 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 in the 3'UTR. The pseudoknot is unusual in that it contains a small stem-loop 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: