Sarcocystis neurona (Protozoa: Apicomplexa): description of oocysts, sporocysts, sporozoites, excystation, and early development.
Abstract: Equine protozoal myeloencephalitis is a major cause of neurological disease in horses from the Americas. Horses are considered accidental intermediate hosts. The structure of sporocysts of the causative agent, Sarcocystis neurona, has never been described. Sporocysts of S. neurona were obtained from the intestines of a laboratory-raised opossum fed skeletal muscles from a raccoon that had been fed sporocysts. Sporocysts were 11.3 by 8.2 microm and contained 4 sporozoites. The appearance of the sporocyst residuum was variable. The residuum of some sporocysts was composed of many dispersed granules, whereas some had granules mixed with larger globules. Excystation was by collapse of the sporocyst along plates. The sporocysts wall was composed of 3 layers: a thin electron-dense outer layer, a thin electron-lucent middle layer, and a thick electron-dense inner layer. The sporocyst wall was thickened at the junctions of the plates. Sporozoites were weakly motile and contained a centrally or posteriorly located nucleus. No retractile or crystalloid body was present, but lipidlike globules about 1 microm in diameter were usually present in the conoidal end of sporozoites. Sporozoites contained 2-4 electron-dense rhoptries and other organelles typical of coccidian zoites. Sporozoites entered host cells in culture and underwent schizogony within 3 days.
Publication Date: 2004-07-27 PubMed ID: 15272465DOI: 10.1645/GE-230RGoogle Scholar: Lookup
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- Journal Article
- Research Support
- Non-U.S. Gov't
- Research Support
- U.S. Gov't
- Non-P.H.S.
- Cell Culture
- Developmental Biology
- Diagnosis
- Disease Diagnosis
- Disease Treatment
- Equine Diseases
- Equine Health
- Equine Protozoal Myeloencephalitis
- Horses
- Infection
- Infectious Disease
- Laboratory Methods
- Microscopy
- Neurological Diseases
- Parasites
- Pathogenesis
- Pathophysiology
- Protozoa
- Sarcocystis
- Veterinary Medicine
- Veterinary Research
Summary
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The research paper describes the microscopic structures and early development of Sarcocystis neurona, a parasite that causes neurological disorders in horses.
Research Background
- The study focuses on the microscopic parasite Sarcocystis neurona, which is known to cause Equine protozoal myeloencephalitis, a major neurological disease in horses.
- This parasite originates primarily in opossums and finds its way into horses, which are considered accidental intermediate hosts.
Methodology
- The research involved obtaining sporocysts (the spore-like stage in the life cycle of certain parasites) of S. neurona from laboratory-raised opossums.
- These opossums were fed skeletal muscles from a raccoon that had also been fed these sporocysts.
- The researchers then visually described these sporocysts using microscopy, focusing on their size, number of sporozoites (infectious cells of the parasite), and the structure of the sporocyst wall.
Findings
- S. neurona sporocysts were approximately 11.3 by 8.2 micrometers and contained 4 sporozoites.
- The sporocyst wall was composed of three layers, two electron-dense, and a thin, electron-lucent layer sandwiched in between. There was thickening noticed at junctions.
- The sporozoites of S. neurona are slightly motile and contain a centrally or posteriorly situated nucleus, and had 1 micron lipid-like globules in one end.
- The structure of the residual matter within the sporocysts varied, being composed of many dispersed granules in some, while others had granules mixed with larger globules.
- The sporozoites then entered host cells under laboratory conditions and underwent further development (schizogony) within 3 days.
Significance
- Understanding the details of the S. neurona sporocyst structure and development helps further our knowledge about the life cycle of such parasites and their interactions with hosts.
- This is crucial to the future development of treatments or preventive measures for equine protozoal myeloencephalitis caused by S. neurona.
Cite This Article
APA
Lindsay DS, Mitchell SM, Vianna MC, Dubey JP.
(2004).
Sarcocystis neurona (Protozoa: Apicomplexa): description of oocysts, sporocysts, sporozoites, excystation, and early development.
J Parasitol, 90(3), 461-465.
https://doi.org/10.1645/GE-230R Publication
Researcher Affiliations
- Department of Biomedical Sciences and Pathobiology, Virginia-Maryland Regional College of Veterinary Medicine, Virginia Tech, Blacksburg, 24061-0342, USA. lindsayd@vt.edu
MeSH Terms
- Animals
- Cell Line
- Chlorocebus aethiops
- Horse Diseases / parasitology
- Horses
- Microscopy, Electron / veterinary
- Microscopy, Electron, Scanning / veterinary
- Opossums / parasitology
- Raccoons
- Sarcocystis / growth & development
- Sarcocystis / physiology
- Sarcocystis / ultrastructure
- Sarcocystosis / parasitology
- Sarcocystosis / veterinary
Citations
This article has been cited 8 times.- Marques C, da Silva B, Nogueira Y, Bezerra T, Tavares A, Borges-Silva W, Gondim L. Brazilian Horses from Bahia State Are Highly Infected with Sarcocystis bertrami.. Animals (Basel) 2022 Dec 10;12(24).
- Dumètre A, Dubey JP, Ferguson DJP. Effect of household bleach on the structure of the sporocyst wall of Toxoplasma gondii.. Parasite 2021;28:68.
- Borges-Silva W, de Jesus RF, Ferreira R, Gondim LFP. Reactivity of Horse Sera to Antigens Derived From Sarcocystis falcatula-Like and Sarcocystis neurona.. Front Vet Sci 2020;7:573016.
- Gondim LFP, Soares RM, Tavares AS, Borges-Silva W, de Jesus RF, Llano HAB, Gondim LQ. Sarcocystis falcatula-like derived from opossum in Northeastern Brazil: In vitro propagation in avian cells, molecular characterization and bioassay in birds.. Int J Parasitol Parasites Wildl 2019 Dec;10:132-137.
- Konradt G, Bianchi MV, Leite-Filho RV, da Silva BZ, Soares RM, Pavarini SP, Driemeier D. Necrotizing meningoencephalitis caused by Sarcocystis falcatula in bare-faced ibis (Phimosus infuscatus).. Parasitol Res 2017 Feb;116(2):809-812.
- Dubey JP, Howe DK, Furr M, Saville WJ, Marsh AE, Reed SM, Grigg ME. An update on Sarcocystis neurona infections in animals and equine protozoal myeloencephalitis (EPM).. Vet Parasitol 2015 Apr 15;209(1-2):1-42.
- Blazejewski T, Nursimulu N, Pszenny V, Dangoudoubiyam S, Namasivayam S, Chiasson MA, Chessman K, Tonkin M, Swapna LS, Hung SS, Bridgers J, Ricklefs SM, Boulanger MJ, Dubey JP, Porcella SF, Kissinger JC, Howe DK, Grigg ME, Parkinson J. Systems-based analysis of the Sarcocystis neurona genome identifies pathways that contribute to a heteroxenous life cycle.. mBio 2015 Feb 10;6(1).
- Talevich E, Kannan N. Structural and evolutionary adaptation of rhoptry kinases and pseudokinases, a family of coccidian virulence factors.. BMC Evol Biol 2013 Jun 6;13:117.
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