Theileria

Theileria
Scientific classification
Domain: Eukaryota
(unranked): SAR
(unranked): Alveolata
Phylum: Apicomplexa
Class: Aconoidasida
Order: Piroplasmida
Family: Theileriidae
Genus: Theileria
Species

Theileria annulata
Theileria electrophori
Theileria equi
Theileria microti
Theileria orientalis
Theileria parva

Theileria is a genus of parasitic protozoan that belongs to the phylum Apicomplexa and is closely related to Plasmodium. Two Theileria species, T. annulata and T. parva, are important cattle parasites.[1] T. annulata causes tropical theileriosis and T. parva causes East Coast fever. Theileria are transmitted by ticks.[2] The genomes of T. orientalis Shintoku[3], Theileria equi WA,[4] Theileria annulata Ankara[5] and Theileria parva Muguga[6] have been sequenced and published.

Theileria equi is a known cause of equine piroplasmosis.[7]

Vaccines against Theileria are in development.[1][8] In May 2010, it was reported that a vaccine to protect cattle against East Coast fever had been approved and registered by the governments of Kenya, Malawi and Tanzania.[9]

Description

Species in this genus undergo exoerythrocytic merogony in the lymphocytes, histiocytes, erythroblasts and other cells of the internal organs.

This is followed by invasion of the erythrocytes by the merozoites, which may or may not reproduce.

When merogony does occur no more than four daughter cells are produced.

The frequent occurrence of elongate bacillary or "bayonet" forms within the erythrocyte is considered as characteristic of this genus.

The organism is transmitted by various tick species including Rhipicephalus, Dermacentor and Haemaphysalis. The organism reproduces in the tick as it progresses through its life stages.[10]

Both T annulata and T parva induce transformation of infected cells of lymphocyte or macrophage/monocyte lineages. T orientalis does not induce uncontrolled proliferation of infected leukocytes and instead multiplies predominantly within infected erythrocytes.

Genomics

The genomes of T. orientalis Shintoku[3], Theileria equi WA,[4] Theileria annulata Ankara[5] and Theileria parva Muguga[6] have been sequenced. Genomic data can be accessed PiroplasmaDB which is part of the Eukaryotic Pathogen Bioinformatic Resource (EuPathDB).[11]

Evolution

The genus is thought to have first appeared in ruminants during the Miocene.

Transmission

Theileria can be transmitted to cattle through tick bites, including the brown ear tick Rhipicephalus spp.

Important species

Theileria parva

The cause of bovine Theileriosis and East Coast fever.[10]

Theileria annulata

Also the cause of bovine Theileriosis.[10]

Theileria equi

Causing equine piroplasmosis.[10]

Treatment

References

  1. 1 2 Morrison W, McKeever D (2006). "Current status of vaccine development against Theileria parasites". Parasitology. 133: S169–87. doi:10.1017/S0031182006001867. PMID 17274845.
  2. ↑ Florin-Christensen, M.; Schnittger, L. (Jan 2009). "Piroplasmids and ticks: a long-lasting intimate relationship". Frontiers in Bioscience. 14 (14): 3064–3073. doi:10.2741/3435. ISSN 1093-9946. PMID 19273257.
  3. 1 2 Hayashida K, Hara Y, Abe T, Yamasaki C, Toyoda A, Kosuge T, Suzuki Y, Sato Y, Kawashima S, Katayama T, Wakaguri H, Inoue N, Homma K, Tada-Umezaki M, Yagi Y, Fujii Y, Habara T, Kanehisa M, Watanabe H, Ito K, Gojobori T, Sugawara H, Imanishi T, Weir W, Gardner M, Pain A, Shiels B, Hattori M, Nene V, Sugimoto C (2012) Comparative genome analysis of three eukaryotic parasites with differing abilities to transform leukocytes reveals key mediators of theileria-induced leukocyte transformation. MBio 3(5). pii: e00204-12. doi: 10.1128/mBio.00204-12
  4. 1 2 Kappmeyer, Lowell S.; Thiagarajan, Mathangi; Herndon, David R.; Ramsay, Joshua D.; Caler, Elisabet; Djikeng, Appolinaire; Gillespie, Joseph J.; Lau, Audrey OT; Roalson, Eric H. (2012-01-01). "Comparative genomic analysis and phylogenetic position of Theileria equi". BMC Genomics. 13: 603. doi:10.1186/1471-2164-13-603. ISSN 1471-2164. PMC 3505731Freely accessible. PMID 23137308.
  5. 1 2 Pain, Arnab; Renauld, Hubert; Berriman, Matthew; Murphy, Lee; Yeats, Corin A.; Weir, William; Kerhornou, Arnaud; Aslett, Martin; Bishop, Richard (2005-07-01). "Genome of the host-cell transforming parasite Theileria annulata compared with T. parva". Science (New York, N.Y.). 309 (5731): 131–133. doi:10.1126/science.1110418. ISSN 1095-9203. PMID 15994557.
  6. 1 2 Gardner, Malcolm J.; Bishop, Richard; Shah, Trushar; de Villiers, Etienne P.; Carlton, Jane M.; Hall, Neil; Ren, Qinghu; Paulsen, Ian T.; Pain, Arnab (2005-07-01). "Genome sequence of Theileria parva, a bovine pathogen that transforms lymphocytes". Science (New York, N.Y.). 309 (5731): 134–137. doi:10.1126/science.1110439. ISSN 1095-9203. PMID 15994558.
  7. ↑ Englund, L. P. (2003). "New diseases and increased risk of diseases in companion animals and horses due to transport". Acta veterinaria Scandinavica. Supplementum. 100: 19–25. ISSN 0065-1699. PMID 16429803.
  8. ↑ Darghouth, A. (Dec 2008). "Review on the experience with live attenuated vaccines against tropical theileriosis in Tunisia: considerations for the present and implications for the future". Vaccine. 26. Suppl 6: G4–G10. doi:10.1016/j.vaccine.2008.09.065. ISSN 0264-410X. PMID 19178892.
  9. ↑ "Cattle disease vaccine launched 30 years after invention". 2010-05-07. SciDev.net (7 May 2010).
  10. 1 2 3 4
  11. ↑ Harb, Omar S.; Roos, David S. (2015-01-01). "The Eukaryotic Pathogen Databases: a functional genomic resource integrating data from human and veterinary parasites". Methods in Molecular Biology (Clifton, N.J.). 1201: 1–18. doi:10.1007/978-1-4939-1438-8_1. ISSN 1940-6029. PMID 25388105.
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