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Máca O, Kouba M, Langrová I, Panská L, Korpimäki E, González-Solís D. The Tengmalm's owl Aegolius funereus (Aves, Strigidae) as the definitive host of Sarcocystis funereus sp. nov. (Apicomplexa). Front Vet Sci 2024; 11:1356549. [PMID: 38384962 PMCID: PMC10880445 DOI: 10.3389/fvets.2024.1356549] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2023] [Accepted: 01/24/2024] [Indexed: 02/23/2024] Open
Abstract
Background Owls have been reported as definitive hosts, whereas wild small mammals (naturally and experimentally) as intermediate hosts of several species of Sarcocystis. Recently, dead fledglings were found infected by an unnamed species of Sarcocystis since its intermediate host was unknown. After collecting additional samples of owls and wild small mammals, the present study focused on elucidating the identity, potential intermediate host, and complete life cycle of the found Sarcocystis through experimentally infected rodents. The developmental stages' morphological and molecular characterizations (28S rRNA gene, ITS1 region) are presented herein. Methods In total, 21 Tengmalm's owl carcasses (15 nestlings, 5 fledglings, and 1 adult male) were collected in Kauhava (west-central Finland) and parasitologically examined by wet mounts. Intestinal mucosa scrapings were used to isolate oocysts/sporocysts and employed for experimental infections in dexamethasone-immunosuppressed BALB/cOlaHsd mice. Additionally, sarcocysts were searched in the skeletal muscle of 95 samples from seven wild small mammal species. All these developmental stages were molecularly characterized by the 28S rRNA gene and ITS1 region. Experimental infections were carried out by using immunosuppressed female 8-week-old BALB/cOlaHsd mice, divided into three groups: (1) water with 15 μg/mL of dexamethasone, (2) water with 30 μg/mL of dexamethasone, (3) no dexamethasone treatment. Each group consisted of four individuals. In each group, two mice were infected with 1,000 sporocysts each, and the remaining two with 10,000 sporocysts each. All mice were euthanized on specific days post-infection. Results The intestinal mucosa of 11 nestlings and 5 fledglings of the Tengmalm's owl were positive for Sarcocystis funereus sp. nov. The adult male owl and all owls' breast and heart muscles were negative for Sarcocystis. Two dexamethasone-immunosuppressed BALB/cOlaHsd mice (group 2) were positive to S. funereus sp. nov. in diaphragm and leg muscles after 22- and 24-day post-infection. Some sarcocysts were found in the wild small mammals. Molecular identification at 28S rRNA revealed sequences from naturally infected Tengmalm's owls, as well as sarcocysts of dexamethasone-immunosuppressed BALB/cOlaHsd mice were 99.87-100% similar to Sarcocystis sp. isolate Af1 previously found in the Tengmalm's owl. At the ITS1 region, the S. funereus sp. nov. isolates Af2 haplotype B and Af3 haplotype A were 98.77-100% identical to Sarcocystis sp. isolate Af1. The sequences from sarcocysts of naturally infected wild small mammals were 75.23-90.30% similar at ITS1 region to those of S. funereus sp. nov. Conclusion The morphological and molecular characterizations and phylogenetic placement of S. funereus sp. nov. are presented here for the first time and support the erection of the new species.
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Affiliation(s)
- Ondřej Máca
- Department of Pathology and Parasitology, State Veterinary Institute Prague, Prague, Czechia
- Department of Zoology and Fisheries, Faculty of Agrobiology, Food and Natural Resources, Czech University of Life Sciences Prague, Prague, Czechia
| | - Marek Kouba
- Department of Ethology and Companion Animal Science, Faculty of Agrobiology, Food and Natural Resources, Czech University of Life Sciences Prague, Prague, Czechia
- Department of Game Management and Wildlife Biology, Faculty of Forestry and Wood Sciences, Czech University of Life Sciences Prague, Prague, Czechia
| | - Iva Langrová
- Department of Zoology and Fisheries, Faculty of Agrobiology, Food and Natural Resources, Czech University of Life Sciences Prague, Prague, Czechia
| | - Lucie Panská
- Department of Zoology and Fisheries, Faculty of Agrobiology, Food and Natural Resources, Czech University of Life Sciences Prague, Prague, Czechia
- Department of Ecology, Faculty of Environmental Sciences, Czech University of Life Sciences Prague, Prague, Czechia
| | - Erkki Korpimäki
- Section of Ecology, Department of Biology, University of Turku, Turku, Finland
| | - David González-Solís
- Department of Systematics and Aquatic Ecology, El Colegio de la Frontera Sur, Chetumal, Quintana Roo, Mexico
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Hay AN, Potter A, Lindsay D, LeRoith T, Zhu J, Cashwell S, Witonsky S, Leeth C. Interferon gamma protective against Sarcocystis neurona encephalitis in susceptible murine model. Vet Immunol Immunopathol 2021; 240:110319. [PMID: 34474260 DOI: 10.1016/j.vetimm.2021.110319] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2021] [Revised: 07/30/2021] [Accepted: 08/26/2021] [Indexed: 11/27/2022]
Abstract
Sarcocystis neurona is the predominant etiological agent of the infectious equine neurologic disease, equine protozoal myeloencephalitis (EPM), which is prevalent in the United States. A wealth of knowledge about S. neurona biology and its life cycle has accumulated over the last several decades. However, much remains unknown about the aberrant equine host's immune response to S. neurona and the relatively high prevalence of exposure to the protozoa but relatively infrequent occurrence of clinical neurologic disease. Mouse models simulating EPM are commonly used to study the disease due to numerous challenges associated with studying the disease in horses. The critical role of the cytokine, interferon gamma (IFNγ), in protection against S. neurona encephalitis has been well established as Ifnγ-/- mice are highly susceptible to S. neurona encephalitis. However, there are discrepancies in the literature regarding S. neurona disease susceptibility in lymphocyte deficient mice, lacking T-lymphocytes and their associated Ifnγ production. In the current study, we investigated S. neurona encephalitis susceptibility in 2 genetically different strains of lymphocyte null mice, C57Bl/6 (B6).scid and Balb/c.scid. The B6.scid mouse was determined to be susceptible to S. neurona encephalitis as 100 % of infected mice developed neurologic disease within 60 days post infection (DPI). The Balb/c.scid mouse was nearly disease resistant as only 10 % of mice developed neurologic disease 60 DPI. Encephalitis was histologically demonstrable and S. neurona was identified in cerebellar samples collected from B6.scid but absent in Balb/c.scid mice. To further investigate the importance of T-lymphocyte derived Ifnγ, T- lymphocytes were adoptively transferred into B6.scid mice. The adoptive transfer of Ifnγ competent T- lymphocytes offered complete protection against S. neurona encephalitis but transfer of Ifnγ deficient T- lymphocytes did not with 100 % of these recipient mice succumbing to S. neruona encephalitis. Histological analysis of collected cerebellar samples confirmed the presences of S. neurona and encephalitis in recipient mice that developed neurologic disease. These studies show that the background strain is critical in studying SCID susceptibility to S. neurona disease and suggest a protective role of Ifnγ producing T- lymphocytes in S. neurona encephalitis susceptible mice.
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Affiliation(s)
- Alayna N Hay
- Virginia Tech, Department of Animal and Poultry Sciences, 175 West Campus Drive, 3280 Litton Reaves Hall, Blacksburg, VA, 24061, United States
| | - Ashley Potter
- Virginia Tech, Department of Animal and Poultry Sciences, 175 West Campus Drive, 3280 Litton Reaves Hall, Blacksburg, VA, 24061, United States
| | - David Lindsay
- Department of Biomedical Sciences and Pathobiology, Virginia- Maryland College of Veterinary Medicine, Virginia Tech, Blacksburg, VA, 24061, United States
| | - Tanya LeRoith
- Department of Biomedical Sciences and Pathobiology, Virginia- Maryland College of Veterinary Medicine, Virginia Tech, Blacksburg, VA, 24061, United States
| | - Jing Zhu
- Virginia Tech, Department of Animal and Poultry Sciences, 175 West Campus Drive, 3280 Litton Reaves Hall, Blacksburg, VA, 24061, United States
| | - Sarah Cashwell
- Virginia Tech, Department of Animal and Poultry Sciences, 175 West Campus Drive, 3280 Litton Reaves Hall, Blacksburg, VA, 24061, United States
| | - Sharon Witonsky
- Department of Large Animal Clinical Sciences, Virginia- Maryland College of Veterinary Medicine, Virginia Tech, Blacksburg, VA, 24061, United States
| | - Caroline Leeth
- Virginia Tech, Department of Animal and Poultry Sciences, 175 West Campus Drive, 3280 Litton Reaves Hall, Blacksburg, VA, 24061, United States.
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Hay AN, Witonsky SG, Lindsay DS, LeRoith T, Zhu J, Kasmark L, Leeth CM. Sarcocystis neurona-Induced Myeloencephalitis Relapse Following Anticoccidial Treatment. J Parasitol 2019. [PMID: 31033388 DOI: 10.1645/18-193] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
Abstract
Sarcocystis neurona is a ubiquitous parasite in the eastern United States, which is the principal causative agent in the neurologic disorder equine protozoal myeloencephalitis (EPM). While much is known about this protozoa's life cycle in its natural host, the opossum (Didelphis virginiana), little is known of how it acts in the aberrant equine host, which displays a high incidence of exposure with a relatively low rate of morbidity. For this study, we employed the popular interferon gamma knockout mouse model to determine the potential for recrudescence of S. neurona infection after treatment with the anticoccidial drug diclazuril. Mice were infected with S. neurona merozoites, and 7-days post-infection (DPI) they were treated with diclazuril for 30 or 60 days or not treated at all. All infected non-treated mice developed neurologic signs consistent with S. neurona infection within 30 DPI. All diclazuril-treated infected mice remained clinically normal while on treatment but developed neurologic signs within 60 days of treatment cessation. Histological examination of cerebella from all infected mice demonstrated characteristic lesions of S. neurona infection, regardless of treatment status. Cerebellar samples collected from infected treated mice, displaying neurologic signs, produced viable S. neurona in culture. However, cerebellar samples collected from infected and neurologically normal mice at the end of a 30-day treatment period did not produce viable S. neurona in culture. Analysis of the humoral immune response in infected mice showed that during treatment IgM antibody production decreased, suggesting the organism was sequestered from immune surveillance. The cessation of treatment and subsequent development of neurologic disease resulted in increased IgM antibody production, suggesting recognition by the immune system at that time. Based on the study results the authors propose that diclazuril was able to inhibit the replication and migration of S. neurona but not fully eliminate the parasite, suggesting recrudescence of infection after treatment is possible.
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Affiliation(s)
- Alayna N Hay
- 1 Department of Animal and Poultry Sciences, Virginia Tech, Blacksburg, Virginia 24061
| | - Sharon G Witonsky
- 2 Department of Large Animal Clinical Sciences, Virginia-Maryland College of Veterinary Medicine, Virginia Tech, Blacksburg, Virginia 24061
| | - David S Lindsay
- 3 Department of Biomedical Sciences and Pathobiology, Virginia-Maryland College of Veterinary Medicine, Virginia Tech, Blacksburg, Virginia 24061
| | - Tanya LeRoith
- 3 Department of Biomedical Sciences and Pathobiology, Virginia-Maryland College of Veterinary Medicine, Virginia Tech, Blacksburg, Virginia 24061
| | - Jing Zhu
- 1 Department of Animal and Poultry Sciences, Virginia Tech, Blacksburg, Virginia 24061
| | - Leah Kasmark
- 1 Department of Animal and Poultry Sciences, Virginia Tech, Blacksburg, Virginia 24061
| | - Caroline M Leeth
- 1 Department of Animal and Poultry Sciences, Virginia Tech, Blacksburg, Virginia 24061
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Reed SM, Furr M, Howe DK, Johnson AL, MacKay RJ, Morrow JK, Pusterla N, Witonsky S. Equine Protozoal Myeloencephalitis: An Updated Consensus Statement with a Focus on Parasite Biology, Diagnosis, Treatment, and Prevention. J Vet Intern Med 2016; 30:491-502. [PMID: 26857902 PMCID: PMC4913613 DOI: 10.1111/jvim.13834] [Citation(s) in RCA: 57] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2015] [Revised: 12/30/2015] [Accepted: 12/30/2015] [Indexed: 11/27/2022] Open
Abstract
Equine protozoal myeloencephalitis (EPM) remains an important neurologic disease of horses. There are no pathognomonic clinical signs for the disease. Affected horses can have focal or multifocal central nervous system (CNS) disease. EPM can be difficult to diagnose antemortem. It is caused by either of 2 parasites, Sarcocystis neurona and Neospora hughesi, with much less known about N. hughesi. Although risk factors such as transport stress and breed and age correlations have been identified, biologic factors such as genetic predispositions of individual animals, and parasite‐specific factors such as strain differences in virulence, remain largely undetermined. This consensus statement update presents current published knowledge of the parasite biology, host immune response, disease pathogenesis, epidemiology, and risk factors. Importantly, the statement provides recommendations for EPM diagnosis, treatment, and prevention.
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Affiliation(s)
- S M Reed
- Rood and Riddle Equine Hospital, 2150 Georgetown Road, Lexington, Kentucky, 40511.,Department of Veterinary Science, Maxwell H. Gluck Equine Research Center, University of Kentucky, Lexington, KY
| | - M Furr
- Department of Physiological Sciences, Center for Veterinary Health Sciences, Oklahoma State University, Stillwater, OK
| | - D K Howe
- Department of Veterinary Science, Maxwell H. Gluck Equine Research Center, University of Kentucky, Lexington, KY
| | - A L Johnson
- New Bolton Center, University of Pennsylvania School of Veterinary Medicine, Kennett Square, PA
| | - R J MacKay
- College of Veterinary Medicine, University of Florida, Gainesville, FL
| | - J K Morrow
- Equine Diagnostic Solutions LLC, Lexington, KY
| | - N Pusterla
- Department of Medicine and Epidemiology, School of Veterinary Medicine, University of California, Davis, CA
| | - S Witonsky
- Virginia-Maryland Regional College of Veterinary Medicine, Blacksburg, VA
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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; 209:1-42. [PMID: 25737052 DOI: 10.1016/j.vetpar.2015.01.026] [Citation(s) in RCA: 60] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2014] [Revised: 01/27/2015] [Accepted: 01/29/2015] [Indexed: 01/27/2023]
Abstract
Equine protozoal myeloencephalitis (EPM) is a serious disease of horses, and its management continues to be a challenge for veterinarians. The protozoan Sarcocystis neurona is most commonly associated with EPM. S. neurona has emerged as a common cause of mortality in marine mammals, especially sea otters (Enhydra lutris). EPM-like illness has also been recorded in several other mammals, including domestic dogs and cats. This paper updates S. neurona and EPM information from the last 15 years on the advances regarding life cycle, molecular biology, epidemiology, clinical signs, diagnosis, treatment and control.
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Affiliation(s)
- J P Dubey
- United States Department of Agriculture, Agricultural Research Service, Animal Parasitic Diseases Laboratory, Beltsville Agricultural Research Center, Building 1001, Beltsville, MD 20705-2350, USA.
| | - D K Howe
- M.H. Gluck Equine Research Center, Department of Veterinary Science, University of Kentucky, Lexington, KY 40546-0099, USA
| | - M Furr
- Marion du Pont Scott Equine Medical Center, Virginia Maryland Regional College of Veterinary Medicine, 17690 Old Waterford Road, Leesburg, VA 20176, USA
| | - W J Saville
- Department of Veterinary Preventive Medicine, The Ohio State University, 1920 Coffey Road, Columbus, OH 43210, USA
| | - A E Marsh
- Department of Veterinary Preventive Medicine, The Ohio State University, 1920 Coffey Road, Columbus, OH 43210, USA
| | - S M Reed
- Rood and Riddle Equine Hospital, Lexington, KY 40511, USA
| | - M E Grigg
- Molecular Parasitology Section, Laboratory of Parasitic Diseases, National Institutes of Health, National Institutes of Allergy, and Infectious Diseases, 4 Center Drive, Room B1-06, Bethesda, MD 20892, USA
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Effects of Experimental Sarcocystis neurona-Induced Infection on Immunity in an Equine Model. J Vet Med 2014; 2014:239495. [PMID: 26464923 PMCID: PMC4590861 DOI: 10.1155/2014/239495] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2014] [Revised: 08/21/2014] [Accepted: 09/15/2014] [Indexed: 11/17/2022] Open
Abstract
Sarcocystis neurona is the most common cause of Equine Protozoal Myeloencephalitis (EPM), affecting 0.5-1% horses in the United States during their lifetimes. The objective of this study was to evaluate the equine immune responses in an experimentally induced Sarcocystis neurona infection model. Neurologic parameters were recorded prior to and throughout the 70-day study by blinded investigators. Recombinant SnSAG1 ELISA for serum and CSF were used to confirm and track disease progression. All experimentally infected horses displayed neurologic signs after infection. Neutrophils, monocytes, and lymphocytes from infected horses displayed significantly delayed apoptosis at some time points. Cell proliferation was significantly increased in S. neurona-infected horses when stimulated nonspecifically with PMA/I but significantly decreased when stimulated with S. neurona compared to controls. Collectively, our results suggest that horses experimentally infected with S. neurona manifest impaired antigen specific response to S. neurona, which could be a function of altered antigen presentation, lack of antigen recognition, or both.
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Surendran N, Zimmerman K, Seleem MN, Sriranganathan N, Boyle SM, Hiltbold EM, Lawler H, Heid B, Witonsky SG. Ability of Brucella abortus rough vaccine strains to elicit DC and innate immunity in lung using a murine respiratory model. Vaccine 2010; 28:7009-15. [DOI: 10.1016/j.vaccine.2010.08.039] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2010] [Revised: 07/31/2010] [Accepted: 08/03/2010] [Indexed: 01/22/2023]
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Witonsky SG, Ellison S, Yang J, Gogal RM, Lawler H, Suzuki Y, Sriranganathan N, Andrews F, Ward D, Lindsay DS. Horses experimentally infected with Sarcocystis neurona develop altered immune responses in vitro. J Parasitol 2009; 94:1047-54. [PMID: 18973416 DOI: 10.1645/ge-1441.1] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2007] [Accepted: 01/23/2008] [Indexed: 11/10/2022] Open
Abstract
Equine protozoal myeloencephalitis (EPM) due to Sarcocystis neurona infection is 1 of the most common neurologic diseases in horses in the United States. The mechanisms by which most horses resist disease, as well as the possible mechanisms by which the immune system may be suppressed in horses that develop EPM, are not known. Therefore, the objectives of this study were to determine whether horses experimentally infected with S. neurona developed suppressed immune responses. Thirteen horses that were negative for S. neurona antibodies in serum and cerebrospinal fluid (CSF) were randomly assigned to control (n = 5) or infected (n = 8) treatment groups. Neurologic exams and cerebrospinal fluid analyses were performed prior to, and following, S. neurona infection. Prior to, and at multiple time points following infection, immune parameters were determined. All 8 S. neurona-infected horses developed clinical signs consistent with EPM, and had S. neurona antibodies in the serum and CSF. Both infected and control horses had increased percentages (P < 0.05) of B cells at 28 days postinfection. Infected horses had significantly decreased (P < 0.05) proliferation responses as measured by thymidine incorporation to nonspecific mitogens phorbol myristate acetate (PMA) and ionomycin (I) as soon as 2 days postinfection.
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Affiliation(s)
- Sharon G Witonsky
- Department of Large Animal Clinical Sciences, Phase II, Duck Pond Dr., Virginia-Maryland Regional College of Veterinary Medicine, Virginia Tech, Blacksburg, Virginia 24061-0442, USA.
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Witonsky SG, Gogal RM, Duncan RB, Norton H, Ward D, Yang J, Lindsay DS. Humoral immunity is not critical for protection against experimental infection with Sarcocystis neurona in B-cell-deficient mice. J Parasitol 2006; 91:830-7. [PMID: 17089750 DOI: 10.1645/ge-488r.1] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
Abstract
Immunodeficient B-cell-deficient mice (mmuMT) were infected with Sarcocystis neurona merozoites to determine the role of B cells and the humoral immune response in protective immunity. As expected, the mice did not seroconvert based on a direct agglutination test. Infected mice did not have significant changes in gross pathology at the time points examined. Histologic changes included mild perivascular and peribronchial infiltrate in the lungs; perivascular infiltrate and mild inflammatory sinusoidal foci in the liver; prominent high endothelial venules in the lymph nodes; and moderate cellular expansion of the periarteriolar sheaths (PALS) in the spleen. Changes resolved by day 60 postinfection. Mice developed significant CD4 and CD8 responses in lymphoid organs, including significant effector (CD45RB(high)) and memory (CD44(high)) CD4 and CD8 responses. Flow cytometry confirmed the lack of B cells. Overall, these data suggest that B cells are not critical to the protective immune response to SN infection.
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Affiliation(s)
- Sharon G Witonsky
- Department of Large Animal Clinical Sciences, Virginia Polytechnic Institute and State University (Virginia Tech), Blacksburg, Virginia 24061, USA.
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Yang J, Ellison S, Gogal R, Norton H, Lindsay DS, Andrews F, Ward D, Witonsky S. Immune response to Sarcocystis neurona infection in naturally infected horses with equine protozoal myeloencephalitis. Vet Parasitol 2006; 138:200-10. [PMID: 16563631 DOI: 10.1016/j.vetpar.2006.02.007] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2005] [Revised: 01/30/2006] [Accepted: 02/07/2006] [Indexed: 11/21/2022]
Abstract
Equine protozoal myeloencephalitis (EPM) is one of the most common neurologic diseases of horses in the United States. The primary etiologic agent is Sarcocystis neurona. Currently, there is limited knowledge regarding the protective or pathophysiologic immune response to S. neurona infection or the subsequent development of EPM. The objectives of this study were to determine whether S. neurona infected horses with clinical signs of EPM had altered or suppressed immune responses compared to neurologically normal horses and if blood sample storage would influence these findings. Twenty clinically normal horses and 22 horses with EPM, diagnosed by the presence of S. neurona specific antibodies in the serum and/or cerebrospinal (CSF) and clinical signs, were evaluated for differences in the immune cell subsets and function. Our results demonstrated that naturally infected horses had significantly (P<0.05) higher percentages of CD4 T-lymphocytes and neutrophils (PMN) in separated peripheral blood leukocytes than clinically normal horses. Leukocytes from naturally infected EPM horses had significantly lower proliferation responses, as measured by thymidine incorporation, to a non-antigen specific mitogen than did clinically normal horses (P<0.05). Currently, studies are in progress to determine the role of CD4 T cells in disease and protection against S. neurona in horses, as well as to determine the mechanism associated with suppressed in vitro proliferation responses. Finally, overnight storage of blood samples appears to alter T lymphocyte phenotypes and viability among leukocytes.
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Affiliation(s)
- Jibing Yang
- Department of Large Animal Clinical Sciences, Phase II, Duck Pond Dr., Virginia-Maryland Regional College of Veterinary Medicine, Virginia Tech, Blacksburg, 24061, USA
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Witonsky SG, Gogal RM, Duncan RB, Norton H, Ward D, Lindsay DS. Prevention of meningo/encephalomyelitis due to Sarcocystis neurona infection in mice is mediated by CD8 cells. Int J Parasitol 2005; 35:113-23. [PMID: 15619522 DOI: 10.1016/j.ijpara.2004.10.021] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2004] [Revised: 10/19/2004] [Accepted: 10/19/2004] [Indexed: 11/29/2022]
Abstract
Immunodeficient CD8 knockout mice were infected with Sarcocystis neurona merozoites, in order to determine the role of CD8 cells in protective immunity. Using a direct agglutination test, all infected mice seroconverted by selected time points. Infected mice developed splenomegaly and bilateral lymphadenopathy. Histological changes included marked follicular development in the spleen, endothelitis and moderate perivascular inflammation in the liver, and meningoencephalitis in the brain. Infected brains were positive for S. neurona by polymerase chain reaction. Corresponding to histopathological changes, there were decreased numbers of B-cells in the spleen. The mice did not have significant memory (CD44hi/CD4) or effector (CD45RBhi/CD4) populations present at the time of euthanasia. Flow cytometry confirmed the lack of CD8 cells. Taken together, these data support previous studies suggesting a critical role for CD8 cells in the prevention of menigoencephalitis in S. neurona-infected mice.
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Affiliation(s)
- Sharon G Witonsky
- Department of Large Animal Clinical Sciences, Virginia-Maryland Regional College of Veterinary Medicine, Phase II, Duck Pond Dr., VMRCVM, Blacksburg, VA 24061-0442, USA.
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