Biology:Theileria

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Theileria is a genus of parasites 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 species 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 infects equid blood cells causing equine piroplasmosis.[7] The disease presents with a variety of clinical conditions, such as fever, depression, jaundice, cramps, haemolytic anaemia, hemoglobinuria and even death, but asymptomatic infections are frequently observed.[8] The most common vectors are the ticks Dermacentor nitens and Rhipicephalus microplus[9] but Amblyomma cajennense was also implicated in the disease transmission.[10]

Vaccines against Theileria are in development.[1][11] In May 2010, a vaccine that was reported to protect cattle against East Coast fever had been approved and registered by the governments of Kenya, Malawi, and Tanzania.[12]

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 elongated 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.[13] 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.

Following infection with Theileria equi, horses may develop detectable antibodies, with seroprevalence varying widely across regions. Serological surveys have revealed a high prevalence of T. equi antibodies in horses and other equids, including 39.8% in Central-Southern Italy[14] and 33.4% in Northern Brazil.[15]

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 though PiroplasmaDB which is part of the Eukaryotic Pathogen Database).[16]

Evolution

The genus is thought to have first appeared in ruminants during the Miocene. It is named for parasitologist Gertrud Theiler, daughter of Arnold Theiler.

Transmission

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

Important species

  • T. parva is the cause of bovine theileriosis and East Coast fever.[13]
  • T. annulata also is a cause of bovine theileriosis.[13]
  • T. equi causes equine piroplasmosis.[13] It was originally classified as Babesia equi in 1901 by Charles Louis Alphonse Laveran, but was reclassified as T. equi in 1998 by Heinz Mehlhorn and Eberhard Schein.[17]

Treatment

  • Buparvaquone is a promising compound for the therapy and prophylaxis of all forms of theileriosis.

References

  1. ↑ 1.0 1.1 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. ↑ 3.0 3.1 "Comparative genome analysis of three eukaryotic parasites with differing abilities to transform leukocytes reveals key mediators of Theileria-induced leukocyte transformation". mBio 3 (5): e00204–12. 2012. doi:10.1128/mBio.00204-12. PMID 22951932. 
  4. ↑ 4.0 4.1 Kappmeyer, Lowell S.; Thiagarajan, Mathangi; Herndon, David R.; Ramsay, Joshua D.; Caler, Elisabet; Djikeng, Appolinaire; Gillespie, Joseph J.; Lau, Audrey OT et al. (2012-01-01). "Comparative genomic analysis and phylogenetic position of Theileria equi". BMC Genomics 13. doi:10.1186/1471-2164-13-603. PMID 23137308. 
  5. ↑ 5.0 5.1 Pain, Arnab; Renauld, Hubert; Berriman, Matthew; Murphy, Lee; Yeats, Corin A.; Weir, William; Kerhornou, Arnaud; Aslett, Martin et al. (2005-07-01). "Genome of the host-cell transforming parasite Theileria annulata compared with T. parva". Science 309 (5731): 131–3. doi:10.1126/science.1110418. PMID 15994557. 
  6. ↑ 6.0 6.1 Gardner, Malcolm J.; Bishop, Richard; Shah, Trushar; de Villiers, Etienne P.; Carlton, Jane M.; Hall, Neil; Ren, Qinghu; Paulsen, Ian T. et al. (2005-07-01). "Genome sequence of Theileria parva, a bovine pathogen that transforms lymphocytes". Science 309 (5731): 134–7. doi:10.1126/science.1110439. PMID 15994558. 
  7. ↑ Mehlhorn, H.; Schein, E. (1998-05-01). "Redescription of Babesia equi Laveran, 1901 as Theileria equi Mehlhorn, Schein 1998" (in en). Parasitology Research 84 (6): 467–475. doi:10.1007/s004360050431. ISSN 1432-1955. https://link.springer.com/article/10.1007/s004360050431. 
  8. ↑ Rothschild, Chantal M. (2013-07-01). "Equine Piroplasmosis". Journal of Equine Veterinary Science 33 (7): 497–508. doi:10.1016/j.jevs.2013.03.189. ISSN 0737-0806. https://linkinghub.elsevier.com/retrieve/pii/S0737080613003079. 
  9. ↑ de Waal, D. T. (1992-01-01). "Equine piroplasmosis: A review". British Veterinary Journal 148 (1): 6–14. doi:10.1016/0007-1935(92)90061-5. ISSN 0007-1935. https://www.sciencedirect.com/science/article/abs/pii/0007193592900615. 
  10. ↑ Scoles, Glen A.; Hutcheson, H. Joel; Schlater, Jack L.; Hennager, Steven G.; Pelzel, Angela M.; Knowles, Don P. (October 2011). "Equine piroplasmosis associated with Amblyomma cajennense Ticks, Texas, USA". Emerging Infectious Diseases 17 (10): 1903–1905. doi:10.3201/eid1710.101182. ISSN 1080-6059. PMID 22000367. 
  11. ↑ 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. 
  12. ↑ "Cattle disease vaccine launched 30 years after invention". 2010-05-07. http://www.scidev.net/en/news/cattle-disease-vaccine-launched-30-years-after-invention.html.  SciDev.net (7 May 2010).
  13. ↑ 13.0 13.1 13.2 13.3 *Theileria reviewed and published by WikiVet, accessed 11 October 2011.
  14. ↑ Bartolomé Del Pino, Leticia Elisa; Roberto, Nardini; Vincenzo, Veneziano; Francesca, Iacoponi; Antonella, Cersini; Luca, Autorino Gian; Francesco, Buono; Teresa, Scicluna Maria (2016-04-01). "Babesia caballi and Theileria equi infections in horses in Central-Southern Italy: Sero-molecular survey and associated risk factors". Ticks and Tick-borne Diseases 7 (3): 462–469. doi:10.1016/j.ttbdis.2016.01.011. ISSN 1877-959X. https://www.sciencedirect.com/science/article/abs/pii/S1877959X16300103. 
  15. ↑ Minervino, Antonio Humberto Hamad; Torres, Allana Cavalcante; Moreira, Thiago Rocha; Vinholte, Brena Peleja; Sampaio, Bruna Matarucco; Bianchi, Daniela; Portela, Juliana Machado; Sarturi, Cristiane et al. (2020). "Factors associated with the prevalence of antibodies against Theileria equi in equids of Western Pará, Brazil" (in en). Transboundary and Emerging Diseases 67 (S2): 100–105. doi:10.1111/tbed.13268. ISSN 1865-1682. 
  16. ↑ Harb, Omar S.; Roos, David S. (2015-01-01). "The Eukaryotic Pathogen Databases: A Functional Genomic Resource Integrating Data from Human and Veterinary Parasites". Parasite Genomics Protocols. Methods in Molecular Biology. 1201. pp. 1–18. doi:10.1007/978-1-4939-1438-8_1. ISBN 978-1-4939-1437-1. 
  17. ↑ Mehlhorn, Heinz; Schein, Eberhard (1998). "Redescription of Babesia equi Laveran, 1901 as Theileria equi Mehlhorn, Schein 1998". Parasitology Research 84 (6): 467–475. doi:10.1007/s004360050431. PMID 9660136. https://doi.org/10.1007/s004360050431. Retrieved June 19, 2020. 

Wikidata ☰ Q5233857 entry



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