Tombusvirus

Tombusvirus is a genus of viruses, in the family Tombusviridae. Plants serve as natural hosts. There are 17 species in this genus. Symptoms associated with this genus include mosaic. The name of the genus comes from Tomato bushy stunt virus.

Taxonomy
The genus contains the following species:
 * Artichoke mottled crinkle virus
 * Carnation Italian ringspot virus
 * Cucumber Bulgarian virus
 * Cucumber necrosis virus
 * Cymbidium ringspot virus
 * Eggplant mottled crinkle virus
 * Grapevine Algerian latent virus
 * Havel River virus
 * Lato River virus
 * Limonium flower distortion virus
 * Moroccan pepper virus
 * Neckar River virus
 * Pelargonium leaf curl virus
 * Pelargonium necrotic spot virus
 * Petunia asteroid mosaic virus
 * Sikte waterborne virus
 * Tomato bushy stunt virus

Structure
Viruses in Tombusvirus are non-enveloped, with icosahedral and spherical geometries, and T=3 symmetry. The diameter is around 28-34 nm. Genomes are linear and non-segmented, positive sense, single-stranded RNA, around 4-5.4kb in length. These virions have a regular surface structure and are composed of 17% nucleic acid.

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, using the premature termination model of subgenomic RNA transcription is the method of transcription. Translation takes place by suppression of termination. The virus exits the host cell by tubule-guided viral movement. Plants serve as the natural host. Transmission routes are mechanical, seed borne, and contact.

The virus uses the cis-regulatory elements, Tombus virus defective interfering (DI) RNA region 3 and Tombusvirus 5' UTR to control expression of defective interfering RNAs and viral RNA replication.