| Tobacco etch virus | |
|---|---|
 | |
| Symptoms of tobacco etch virus inburley tobacco (Nicotiana tabacum) | |
Virus classification | |
| (unranked): | Virus |
| Realm: | Riboviria |
| Kingdom: | Orthornavirae |
| Phylum: | Pisuviricota |
| Class: | Stelpaviricetes |
| Order: | Patatavirales |
| Family: | Potyviridae |
| Genus: | Potyvirus |
| Species: | Tobacco etch virus |
| Synonyms | |
datura Z virus | |
Tobacco etch virus (TEV) is aplant virus in the genusPotyvirus and familyPotyviridae.[1] Like other members of the genusPotyvirus, TEV has a monopartitepositive-sense, single-stranded RNA genome surrounded by acapsid made from a single viral encoded protein. The virus is a filamentous particle that measures about 730 nm in length. It is transmissible in a non-persistent manner by more than 10 species ofaphids includingMyzus persicae. It also is easily transmitted by mechanical means but is not known to be transmitted by seeds.[2]
This virus infects many species ofSolanaceae. Agriculturally important crops that it infects include several species ofCapsicum (i.e.C. annuum,C. frutescens), tomato (Lycopersicon esculentum), andtobacco (Nicotiana spp.).
It also infects manyperennial weed species that can act as virus reservoirs for susceptible agricultural crops. These weed species includeSolanum nigrum (nightshade),S. aculeatissimum (soda apple),Chenopodium album (pigweed),Datura stramonium (jimson weed),Linaria canadensis (blue toadflax), andPhysalis spp. (ground cherry). Thus, recommendations for the control of this virus include the control of weeds in and around susceptible solanaceous crops.[3]
Symptoms seen on plants infected with this virus can vary depending on the plant. However typical symptoms include vein clearing, mottling, and necrotic lines or etching. Symptoms can occur on leaves and fruit and the plants can become stunted.[4]
Like other potyviruses, TEV makes viral inclusions that can be seen in the light microscope if properly stained.[5][6][7] This particular potyvirus makes two kinds of inclusions that can be diagnostic in a known host. One of the inclusions is the cylindrical inclusions found in the cytoplasm of infected cells and the second inclusion is found in the nucleus. Neither inclusion type stains in the nucleic acid stain (AzureA). (Inclusions of tobacco etch virus in various hosts.)
TEV appears to be a virus that evolved in theNew World.[8] It has been reported in Canada, the United States (including Hawaii), Mexico and Puerto Rico in North America and in Venezuela in South America.[2]
Potyvirus RNA codes for at least seven different proteins.[9] One of them is a protease. TheTEV protease is a highly site-specific protease that biochemists have used to their advantage to create aprotein purification system by incorporating TEV protease's recognition site into protein purification tags.
A gene construct is created containing the protein of interest fused to a TEV protease recognition site, followed by anaffinity tag, such as apolyhistidine-tag. Followingaffinity chromatography, the purified protein is then treated with TEV protease. TEV protease cleaves at its recognition site, removing the affinity tag. This allows for affinity purification of proteins that are not well-behaved when fused to protein tags.[10]