Genus Tospovirus
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Type Species |
Tomato spotted wilt virus |
(TSWV) |
Distinguishing Features
Morphogenesis occurs in clusters in the cisternae of the endoplasmic reticulum of host cells. Nucleocapsid material may accumulate in the cytoplasm in dense masses; these masses may be composed of defective particles. The morphology of a tospovirus is shown in Figure 8. The consensus terminal sequences of the L, M and S genome segments are UCUCGUUA . . . at the 3
-end and AGAGCAAU . . . at the 5-end. Both the M and S segment RNAs of tospoviruses utilize an ambisense coding strategy. The virion glycoproteins G1 and G2 are encoded in the complementary-sense RNA of the M segment, and a nonstructural protein, NSm, is encoded in the genome-sense RNA. The S segment encodes the nucleocapsid protein in the complementary-sense RNA and a nonstructural protein, NSs, in the genome-sense RNA. The NSm protein plays a role in cell-to-cell movement of the virus during systemic infection of plants; NSs may form paracrystalline or filamentous inclusions in infected plant cells or when expressed in insect cells from recombinant baculovirus.
At least eight species of thrips in the genera Frankliniella (five) and Thrips (three) have been reported to transmit tospoviruses, and the G1 and/or G2 glycoproteins are involved in virus-vector interactions. Transmission can also be achieved through infected plant sap, and within an infected plant tospoviruses are transported mainly as free nucleocapsids. For the type species Tomato spotted wilt virus (TSWV) more than 925 plant species belonging to 70 botanical families are known to be susceptible whereas the other tospovirus species have much narrower host ranges.
List of Species Demarcation Criteria in the Genus
Species are defined on the basis of their vector specificity, their plant host range, serological relationships of the N protein and that their N protein sequence should show less than 90% amino acid identity with that of any other described tospovirus species.
List of Species in the Genus
Official virus species names are in italics. Tentative virus species names, alternative names ( ), strains or serotypes are not italicized. Virus names, vector types, genome sequence accession numbers [ ], and assigned abbreviations ( ) are:
Species in the Genus
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Groundnut bud necrosis virus |
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(GBNV) |
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(Peanut bud necrosis virus) |
T. palmi |
[L: AF025538] |
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[M: U42555] |
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[S: U27809] |
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Groundnut ringspot virus |
F. occidentalis |
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(GRSV) |
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F. schultzei |
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Groundnut yellow spot virus |
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(GYSV) |
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(Peanut yellow spot virus) |
N.D. |
[S: AF013994] |
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Impatiens necrotic spot virus |
F. occidentalis |
[L: X93218] |
(INSV) |
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[M: M74904] |
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[S: X66972] |
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Tomato chlorotic spot virus |
F. occidentalis |
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(TCSV) |
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F. schultzei |
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F. intonsa |
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Tomato spotted wilt virus |
F. occidentalis |
[L: (BR-01) D10066] |
(TSWV) |
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F. schultzei |
[M: (BR-01) S48091] |
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F. intonsa |
[S: (BR-01) D00645] |
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F. fusca |
[S: (B) L12048] |
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F. bispinosa |
[S: (BL) L20953] |
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T. tabaci |
[S: (L3) D13926] |
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T. setosus |
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T. palmi |
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Watermelon silver mottle virus |
T. palmi |
[M: U75379] |
(WSMoV) |
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[S: Z46419] |
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Zucchini lethal chlorosis virus |
N.D. |
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(ZLCV) |
Tentative Species in the Genus
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Chrysanthemum stem necrosis virus |
F. schultzei |
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(CSNV) |
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Iris yellow spot virus |
N.D. |
[S: (iris isolate NL) AF001387] |
(IYSV) |
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Groundnut chlorotic fan-spot virus |
N.D. |
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(GCFSV) |
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Physalis severe mottle virus |
N.D. |
[S: AF067151] |
(PhySMV) |
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Watermelon bud necrosis virus |
N.D. |
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(WBNV) |
Unassigned Species in the Family
There are seven groups (19 viruses) and 21 ungrouped viruses which have not been assigned to a recognized genera in the family Bunyaviridae. For most, no biochemical characterization of the viruses has been reported to determine their taxonomic status.
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The groups are: |
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Bhanja virus |
(BHAV) |
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Forecariah virus |
(FORV) |
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Kismayo virus |
(KISV) |
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Kaisodi virus |
(KSOV) |
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Lanjan virus |
(LJNV) |
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Silverwater virus |
(SILV) |
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Mapputta virus |
(MAPV) |
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Gan Gan virus |
(GGV) |
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Maprik virus |
(MPKV) |
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Trubanaman virus |
(TRUV) |
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Okola virus |
(OKOV) |
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Tanga virus |
(TANV) |
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Resistencia virus |
(RTAV) |
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Antequera virus |
(ANTV) |
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Barranqueras virus |
(BQSV) |
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Upolu virus |
(UPOV) |
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Aransas Bay virus |
(ABV) |
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Yogue virus |
(YOGV) |
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Kasokero virus |
(KASV) |
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Ungrouped viruses: |
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Bangui virus |
(BGIV) |
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Belem virus |
(BLMV) |
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Belmont virus |
(BELV) |
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Bobaya virus |
(BOBV) |
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Caddo Canyon virus |
(CDCV) |
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Chim virus |
(CHIMV) |
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Enseada virus |
(ENSV) |
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Issyk-Kul virus |
(ISKV) |
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Keterah virus |
(KTRV) |
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Kowanyama virus |
(KOWV) |
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Lone Star virus |
(LSV) |
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Pacora virus |
(PCAV) |
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Razdan virus |
(RAZV) |
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Salanga virus |
(SGAV) |
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Santarem virus |
(STMV) |
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Sunday Canyon virus |
(SCAV) |
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Tai virus |
(TAIV) |
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Tamdy virus |
(TDYV) |
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Tataguine virus |
(TATV) |
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Wanowrie virus |
(WANV) |
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Witwatersrand virus |
(WITV) |
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Yacaaba virus |
(YACV) |
Phylogenetic Relationships within the Family
As documented above the analogous genes and gene products of viruses in the different genera vary widely in size, and there is little obvious global similarity at either nucleotide or amino acid level. Attempts to produce convincing alignments of either genome segments or structural proteins from which to generate phylogenetic trees have so far proved unsuccessful, with the exception of the putative polymerase domain of the L proteins. Such analysis suggests that viruses in the family Bunyaviridae fall into two major lineages, comprising bunyaviruses, hantaviruses and tospoviruses on one, and nairoviruses and phleboviruses on the other. The significant point to note is that L protein phylogeny does not segregate with the use of an ambisense coding strategy (Fig. 9).
Similarity with Other Taxa
The plant-infecting tenuiviruses show some similarities to the family Bunyaviridae, particularly the Phlebovirus genus. Tenuiviruses have a ssRNA genome comprising four or five segments which encode proteins using a negative or ambisense coding strategy. The tenuivirus RNA terminal sequences are conserved and the 3 and 5-sequences exhibit inverted complementarity; the conserved 3-sequence, UGUGUUUCAG . . . , is similar to the consensus phlebovirus sequence. Tenuiviruses employ a cap-snatching mechanism to prime viral mRNA synthesis, similar to members of the family Bunyaviridae. Weak sequence homology has been noted between Rice stripe virus 94 
103 protein and phlebovirus glycoproteins, and between tenuivirus nucleocapsid proteins and those of phleboviruses.
Derivation of Names
Bunya: from Bunyamwera; place in Uganda, where type virus was isolated.
Hanta: from Hantaan virus; river in South Korea near where type virus was isolated.
Nairo: from Nairobi sheep disease; first reported disease caused by member virus.
Phlebo: refers to phlebotomine vectors of sandfly fever group viruses; Greek phlebos, “vein”.
Tospo: from Tomato spotted wilt virus.
