| Turnip crinkle virus | |
|---|---|
Virus classification  | |
| (unranked): | Virus |
| Realm: | Riboviria |
| Kingdom: | Orthornavirae |
| Phylum: | Kitrinoviricota |
| Class: | Tolucaviricetes |
| Order: | Tolivirales |
| Family: | Tombusviridae |
| Genus: | Betacarmovirus |
| Species: | Turnip crinkle virus |
Turnip crinkle virus (TCV) is a plant pathogenic virus of the family Tombusviridae . It was first isolated from turnip (Brassica campestris ssp. rapa).
TCV is a small (4054 nucleotides), single-stranded, positive-sense RNA virus (viral RNA is in the same orientation as mRNA). It has been shown to infect various types of plant species, including the common plant models Arabidopsis thaliana and Nicotiana benthamiana . Its gRNA encodes for five proteins: p28 and p88 (replication), p8 and p9 (movement) and CP (coat protein or encapsidation). [1] The structure of the virus was determined to 3.2 Ångstrom resolution using x-ray crystallography in 1986. It is structurally quite similar to the tomato bushy stunt virus. [2]
A number of non-coding RNA elements have been characterised in the TCV genome; examples are hairpin 5 and the core promoter. [3] [4]
Replication of the viral RNA begins with the migration of p28 to the mitochondrial membrane. p28 migrates to and invaginates the outer mitochondrial membrane; several p88 molecules are brought the newly formed vesicles. The viral RNA binds to the p28 bound to the membrane and the RNA dependent RNA polymerase, or p88, initiates replication of the positive strand RNA to produce a minus strand intermediate. The negative-strand intermediate is used as a template to produce progeny positive strand RNA. [5] The coat proteins p8, p9, and p38, are involved in movement in the plant. [6]
Small, helper viruses known as satellite RNA have been found to co-infect plants only in the presence of TCV. [7] These non-coding RNAs up-regulate the symptoms of TCV infection. The satellite RNA are dependent of the TCV and host machinery to propagate. Satellite C shares sequence homology with the 3'end of the TCV, while satellite D shares sequence homology with the 5'end of satellite C.[ citation needed ]
Much research has been done on TCV and the way that it affects Arabidopsis thaliana (thale cress). Arabidopsis tents to be very susceptible to TCV, along with several other species other than turnips. It is used for research as its susceptibility and simplicity make it a good model organism. Research has shown that only satellite C produces any symptoms in Arabidopsis. The same research has shown that how much the plant is affected by the Virus depends largely on the ecotype, as the Dijon-ecotype of Arabidopsis thaliana seems to be far more susceptible than other types. [8] It has also been shown that light affects the resistance of Arabidopsis to TCV, and that inoculations proved to be ineffective without the plant being exposed to light. [9] Research has also been done on what part of TCV is recognized by the strains of Arabidopsis that are resistant to TCV, and it appears to be the Amino terminus of the coat protein. This was determined by using Viruses both with and without the Amino terminus. [10]
Viroids are small single-stranded, circular RNAs that are infectious pathogens. Unlike viruses, they have no protein coating. All known viroids are inhabitants of angiosperms, and most cause diseases, whose respective economic importance to humans varies widely.
Tobacco mosaic virus (TMV) is a positive-sense single-stranded RNA virus species in the genus Tobamovirus that infects a wide range of plants, especially tobacco and other members of the family Solanaceae. The infection causes characteristic patterns, such as "mosaic"-like mottling and discoloration on the leaves. TMV was the first virus to be discovered. Although it was known from the late 19th century that a non-bacterial infectious disease was damaging tobacco crops, it was not until 1930 that the infectious agent was determined to be a virus. It is the first pathogen identified as a virus. The virus was crystallised by W.M. Stanley.
A poliovirus, the causative agent of polio, is a serotype of the species Enterovirus C, in the family of Picornaviridae. There are three poliovirus serotypes: types 1, 2, and 3.
Defective interfering particles (DIPs), also known as defective interfering viruses, are spontaneously generated virus mutants in which a critical portion of the particle's genome has been lost due to defective replication or non-homologous recombination. The mechanism of their formation is presumed to be as a result of template-switching during replication of the viral genome, although non-replicative mechanisms involving direct ligation of genomic RNA fragments have also been proposed. DIPs are derived from and associated with their parent virus, and particles are classed as DIPs if they are rendered non-infectious due to at least one essential gene of the virus being lost or severely damaged as a result of the defection. A DIP can usually still penetrate host cells, but requires another fully functional virus particle to co-infect a cell with it, in order to provide the lost factors.
Cauliflower mosaic virus (CaMV) is a member of the genus Caulimovirus, one of the six genera in the family Caulimoviridae, which are pararetroviruses that infect plants. Pararetroviruses replicate through reverse transcription just like retroviruses, but the viral particles contain DNA instead of RNA.
A satellite is a subviral agent that depends on the coinfection of a host cell with a helper virus for its replication. Satellites can be divided into two major classes: satellite viruses and satellite nucleic acids. Satellite viruses, which are most commonly associated with plants, are also found in mammals, arthropods, and bacteria. They encode structural proteins to enclose their genetic material, which are therefore distinct from the structural proteins of their helper viruses. Satellite nucleic acids, in contrast, do not encode their own structural proteins, but instead are encapsulated by proteins encoded by their helper viruses. The genomes of satellites range upward from 359 nucleotides in length for satellite tobacco ringspot virus RNA (STobRV).
An arenavirus is a bisegmented ambisense RNA virus that is a member of the family Arenaviridae. These viruses infect rodents and occasionally humans. A class of novel, highly divergent arenaviruses, properly known as reptarenaviruses, have also been discovered which infect snakes to produce inclusion body disease. At least eight arenaviruses are known to cause human disease. The diseases derived from arenaviruses range in severity. Aseptic meningitis, a severe human disease that causes inflammation covering the brain and spinal cord, can arise from the lymphocytic choriomeningitis virus. Hemorrhagic fever syndromes, including Lassa fever, are derived from infections such as Guanarito virus, Junin virus, Lassa virus, Lujo virus, Machupo virus, Sabia virus, or Whitewater Arroyo virus. Because of the epidemiological association with rodents, some arenaviruses and bunyaviruses are designated as roboviruses.
Tomato bushy stunt virus (TBSV) is a virus of the tombusvirus family. It was first reported in tomatoes in 1935 and primarily affects vegetable crops, though it is not generally considered an economically significant plant pathogen. Depending upon the host, TBSV causes stunting of growth, leaf mottling, and deformed or absent fruit. The virus is likely to be soil-borne in the natural setting, but can also transmitted mechanically, for example through contaminated cutting tools. TBSV has been used as a model system in virology research on the life cycle of plant viruses, particularly in experimental infections of the model host plant Nicotiana benthamiana.
Alfalfa mosaic virus (AMV), also known as Lucerne mosaic virus or Potato calico virus, is a worldwide distributed phytopathogen that can lead to necrosis and yellow mosaics on a large variety of plant species, including commercially important crops. It is the only Alfamovirus of the family Bromoviridae. In 1931 Weimer J.L. was the first to report AMV in alfalfa. Transmission of the virus occurs mainly by some aphids, by seeds or by pollen to the seed.
Tombusvirus 3′ UTR is an important cis-regulatory region of the Tombus virus genome.
Tombusvirus 5′ UTR is an important cis-regulatory region of the Tombus virus genome.
The turnip crinkle virus (TCV) core promoter hairpin (Pr) is an RNA element located in the 3' UTR of the viral genome that is required for minus strand RNA synthesis. The picture shown is not the TCV core promoter, but an upstream hairpin that is also required for replication of the virus.
The TCV hairpin 5 (H5) is an RNA element found in the turnip crinkle virus. This RNA element is composed of a stem-loop that contains a large symmetrical internal loop (LSL). H5 can repress minus-strand synthesis when the 3' side of the LSL pairs with the 4 bases at the 3'-terminus of the RNA(GCCC-OH).
Rice hoja blanca tenuivirus (RHBV), meaning "white leaf rice virus", is a plant virus in the family Phenuiviridae. RHBV causes Hoja blanca disease (HBD), which affects the leaves of the rice plant Oryza sativa, stunting the growth of the plant or killing it altogether. RHBV is carried by an insect vector, Tagosodes orizicolus, a type of planthopper. The virus is found in South America, Mexico, throughout Central America, the Caribbean region, and the southern United States. In South America, the disease is endemic to Colombia, Venezuela, Ecuador, Peru, Suriname, French Guiana and Guyana.
Nonstructural protein 5A (NS5A) is a zinc-binding and proline-rich hydrophilic phosphoprotein that plays a key role in Hepatitis C virus RNA replication. It appears to be a dimeric form without trans-membrane helices.
Hepatitis B virus (HBV) is a partially double-stranded DNA virus, a species of the genus Orthohepadnavirus and a member of the Hepadnaviridae family of viruses. This virus causes the disease hepatitis B.
In molecular biology, Turnip crinkle virus (TCV) hairpin H4 is an RNA hairpin found at the 3' end of the Turnip crinkle virus (TCV) genome.
Positive-strand RNA viruses are a group of related viruses that have positive-sense, single-stranded genomes made of ribonucleic acid. The positive-sense genome can act as messenger RNA (mRNA) and can be directly translated into viral proteins by the host cell's ribosomes. Positive-strand RNA viruses encode an RNA-dependent RNA polymerase (RdRp) which is used during replication of the genome to synthesize a negative-sense antigenome that is then used as a template to create a new positive-sense viral genome.
Modoc virus (MODV) is a rodent-associated flavivirus. Small and enveloped, MODV contains positive single-stranded RNA. Taxonomically, MODV is part of the Flavivirus genus and Flaviviridae family. The Flavivirus genus includes nearly 80 viruses, both vector-borne and no known vector (NKV) species. Known flavivirus vector-borne viruses include Dengue virus, Yellow Fever virus, tick-borne encephalitis virus, and West Nile virus.
James C. Carrington is a plant biologist and the current president of the Donald Danforth Plant Science Center. In 2005 he was elected a fellow of the American Association for the Advancement of Science and in 2008 he was elected to the National Academy of Sciences.
