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Marsh AE, Chaney SB, Howe DK, Saville WJ, Reed SM. Small sarcocysts can be a feature of experimental infections with Sarcocystis neurona merozoites. Vet Parasitol 2017; 245:116-118. [PMID: 28969829 DOI: 10.1016/j.vetpar.2017.08.017] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2017] [Revised: 08/20/2017] [Accepted: 08/23/2017] [Indexed: 11/18/2022]
Abstract
Several reports indicate the presence of small tissue cysts associated with Sarcocystis neurona infections. Several failed attempts to develop tissue cysts in potential intermediate host using in vitro derived parasites originally isolated from horses with equine protozoal myeloencephalitis suggest that the experimental methods to achieve bradyzoites with those isolates was not possible. Those prior studies reported the lack of detectable sarcocysts based on histology and in vivo feeding trials. A recent report of successful production and detection of small sarcocysts triggered us to review archived tissues from earlier experimental infection studies. The retrospective review sought to determine if small sized sarcocysts were not detected due to their relatively smaller size and infrequency as compared to larger sized sarcocysts produced with other isolates in these experimental inoculation trials. Tissues from two prior in vivo inoculation studies, involving in vitro-produced parasites inoculated into laboratory-reared cats and raccoons, were re-examined by immunohistochemistry staining to more easily detect the tissue cysts. In the experimental cat study no small tissue cysts were seen, consistent with the original publication results. However, in the experimental raccoon study, one raccoon inoculated with an EPM-derived isolate, SN-UCD1, had small sarcocysts not reported in the original publication. This retrospective study suggests that much closer scrutiny of tissues, including the use of immunohistochemistry on tissue sections is required to detect the smaller S. neurona sarcocysts associated with the experimental inoculations of the isolates originally derived from horses with EPM.
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Affiliation(s)
- Antoinette E Marsh
- Department of Veterinary Preventive Medicine, College of Veterinary Medicine, Ohio State University, Columbus, OH, 43210, USA.
| | - Sarah B Chaney
- Department of Veterinary Preventive Medicine, College of Veterinary Medicine, Ohio State University, Columbus, OH, 43210, USA
| | - Daniel K Howe
- Department of Veterinary Science, University of Kentucky, 108 Gluck Equine Research Center, Lexington, KY, 40546, USA
| | - William J Saville
- Department of Veterinary Preventive Medicine, College of Veterinary Medicine, Ohio State University, Columbus, OH, 43210, USA
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Chaney SB, Marsh AE, Lewis S, Carman M, Howe DK, Saville WJ, Reed SM. Sarcocystis neurona manipulation using culture-derived merozoites for bradyzoite and sporocyst production. Vet Parasitol 2017; 238:35-42. [PMID: 28372843 DOI: 10.1016/j.vetpar.2017.03.013] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2016] [Revised: 03/11/2017] [Accepted: 03/16/2017] [Indexed: 11/28/2022]
Abstract
Equine protozoal myeloencephalitis (EPM) remains a significant central nervous system disease of horses in the American continents. Sarcocystis neurona is considered the primary causative agent and its intermediate life stages are carried by a wide host-range including raccoons (Procyon lotor) in North America. S. neurona sarcocysts mature in raccoon skeletal muscle and can produce central nervous system disease in raccoons, mirroring the clinical presentation in horses. The study aimed to develop laboratory tools whereby the life cycle and various life stages of S. neurona could be better studied and manipulated using in vitro and in vivo systems and compare the biology of two independent isolates. This study utilized culture-derived parasites from S. neurona strains derived from a raccoon or from a horse to initiate raccoon infections. Raccoon tissues, including fresh and cryopreserved tissues, were used to establish opossum (Didelphis virginiana) infections, which then shed sporocyts with retained biological activity to cause encephalitis in mice. These results demonstrate that sarcocysts can be generated using in vitro-derived S. neurona merozoites, including an isolate originally derived from a naturally infected horse with clinical EPM. This study indicates the life cycle can be significantly manipulated in the laboratory without affecting subsequent stage development, allowing further purification of strains and artificial maintenance of the life cycle.
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Affiliation(s)
- Sarah B Chaney
- Veterinary Biosciences, College of Veterinary Medicine, The Ohio State University, Columbus, OH, 43210, United States
| | - Antoinette E Marsh
- Department of Veterinary Preventive Medicine, College of Veterinary Medicine, The Ohio State University, Columbus, OH, 43210, United States.
| | - Stephanie Lewis
- Department of Veterinary Preventive Medicine, College of Veterinary Medicine, The Ohio State University, Columbus, OH, 43210, United States
| | - Michelle Carman
- Department of Veterinary Preventive Medicine, College of Veterinary Medicine, The Ohio State University, Columbus, OH, 43210, United States
| | - Daniel K Howe
- Department of Veterinary Science, University of Kentucky, 108 Gluck Equine Research Center, Lexington, KY, 40546, United States
| | - William J Saville
- Department of Veterinary Preventive Medicine, College of Veterinary Medicine, The Ohio State University, Columbus, OH, 43210, United States
| | - Stephen M Reed
- Rood & Riddle, Equine Hospital, Lexington, KY, 40511, United States
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Diseases of the Nervous System. Vet Med (Auckl) 2017. [PMCID: PMC7322266 DOI: 10.1016/b978-0-7020-5246-0.00014-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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