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Abstract
Advances in the understanding of equine protozoal myeloencephalitis (EPM) are reviewed. It is now apparent that EPM can be caused by either of 2 related protozoan parasites, Sarcocystis neurona and Neospora hughesi, although S neurona is the most common etiologic pathogen. Horses are commonly infected, but clinical disease occurs only infrequently; the factors influencing disease occurrence are not well understood. Epidemiologic studies have identified risk factors for the development of EPM, including the presence of opossums and prior stressful health-related events. Attempts to reproduce EPM experimentally have reliably induced antibody responses in challenged horses, but have not consistently produced neurologic disease. Diagnosis of EPM has improved by detecting intrathecal antibody production against the parasite. Sulfadiazine/pyrimethamine (ReBalance) and the triazine compounds diclazuril (Protazil) and ponazuril (Marquis) are effective anticoccidial drugs that are now available as FDA-approved treatments for EPM.
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Affiliation(s)
- Robert J MacKay
- Department of Large Animal Clinical Sciences, College of Veterinary Medicine, University of Florida, 2015 Southwest 16th Avenue, PO Box 100136, Gainesville, FL 32610-0125, USA
| | - Daniel K Howe
- Department of Veterinary Science, M.H. Gluck Equine Research Center, University of Kentucky, 108 Gluck Equine Research Center, Lexington, KY 40546-0099, USA.
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2
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Hay AN, Wagner B, Leeth CM, LeRoith T, Cecere TE, Lahmers KK, Andrews FM, Werre SR, Johnson AL, Clark CK, Pusterla N, Reed SM, Lindsay DS, Taylor S, Estell KE, Furr M, MacKay RJ, Del Piero F, Witonsky SG. Horses affected by EPM have increased sCD14 compared to healthy horses. Vet Immunol Immunopathol 2021; 242:110338. [PMID: 34717126 DOI: 10.1016/j.vetimm.2021.110338] [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: 02/18/2021] [Revised: 10/05/2021] [Accepted: 10/11/2021] [Indexed: 11/29/2022]
Abstract
Equine protozoal myeloencephalitis (EPM) is a debilitating neurologic disease affecting horses across the Americas. Gaps in understanding the inflammatory immune response in EPM-affected horses create difficulties with diagnosis and treatment, subsequently negatively impacting the prognosis of affected horses. The purpose of the current study was to evaluate circulating levels of the inflammatory immune marker soluble CD14 (sCD14), in horses with EPM (n = 7) and determine if they differed from healthy neurologically normal horses (n = 6). Paired sera and cerebrospinal fluid (CSF) samples were analyzed for sCD14. Inclusion criteria for EPM horses consisted of the presence of neurologic signs consistent with EPM, Sarcocystis neurona surface antigens 2, 4/3 (SnSAG 2, 4/3) ELISA serum: CSF antibody ratio ≤ 100, and a postmortem diagnosis of EPM. Control horses were neurologically normal, healthy horses with SnSAG 2, 4/3 ELISA serum: CSF antibody ratios of > 100. Serum anti-Sarcocystis neurona antibodies indicate that healthy control horses were exposed to S. neurona but resistant to developing clinical EPM. EPM cases had significantly greater concentrations of sCD14 in CSF samples compared to control horses and increased serum sCD14 concentrations. A positive correlation between sCD14 serum and CSF concentrations was observed in EPM-affected horses but not healthy horses. Soluble CD14 is an inflammatory marker, and the study results suggest it is elevated in EPM patients. When performed in conjunction with clinical evaluation and standard antibody testing, there may be potential for sCD14 to be utilized as a correlate for EPM.
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Affiliation(s)
- Alayna N Hay
- Department of Animal and Poultry Sciences, Virginia Tech, Blacksburg, VA, USA
| | - Bettina Wagner
- Department of Population Medicine and Diagnostic Sciences, Cornell University, Ithaca, NY, USA
| | - Caroline M Leeth
- Department of Animal and Poultry Sciences, Virginia Tech, Blacksburg, VA, USA
| | - Tanya LeRoith
- Department of Biomedical Sciences and Pathobiology, Virginia- Maryland College of Veterinary Medicine, Virginia Tech, Blacksburg, VA, USA
| | - Thomas E Cecere
- Department of Biomedical Sciences and Pathobiology, Virginia- Maryland College of Veterinary Medicine, Virginia Tech, Blacksburg, VA, USA
| | - Kevin K Lahmers
- Department of Biomedical Sciences and Pathobiology, Virginia- Maryland College of Veterinary Medicine, Virginia Tech, Blacksburg, VA, USA
| | - Frank M Andrews
- Equine Health Studies Program, Department of Veterinary Clinical Sciences, School of Veterinary Medicine, Louisiana State University, Baton Rouge, LA, USA
| | - Stephen R Werre
- Department of Population Health Sciences, Virginia- Maryland College of Veterinary Medicine, Virginia Tech, Blacksburg, VA, USA
| | - Amy L Johnson
- Department of Clinical Studies, University of Pennsylvania, School of Veterinary Medicine, New Bolton Center, Kennett Square, PA, USA
| | | | - Nicola Pusterla
- Department of Medicine and Epidemiology, School of Veterinary Medicine, University of California, Davis, Davis, CA, USA
| | | | - David S Lindsay
- Department of Biomedical Sciences and Pathobiology, Virginia- Maryland College of Veterinary Medicine, Virginia Tech, Blacksburg, VA, USA
| | - Sandra Taylor
- Department of Veterinary Clinical Sciences, College of Veterinary Medicine, Purdue University, West Lafayette, IN, USA
| | - Krista E Estell
- Department of Large Animal Clinical Sciences, Marion duPont Scott Equine Medical Center, Leesburg, VA, USA
| | - Martin Furr
- Department of Physiological Sciences, Center for Veterinary Health Sciences, Oklahoma State University, Stillwater, OK, USA
| | - Robert J MacKay
- Department of Large Animal Clinical Sciences, University of Florida, Gainesville, FL, USA
| | - Fabio Del Piero
- Department of Pathobiological Sciences, School of Veterinary Medicine, Louisiana State University, Baton Rouge, LA, USA
| | - Sharon G Witonsky
- Department of Large Animal Clinical Sciences, Virginia- Maryland College of Veterinary Medicine, Virginia Tech, Blacksburg, VA, USA.
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Sánchez-Ovejero C, Akdur E, Manzano-Román R, Hernández-González A, González-Sánchez M, Becerro-Recio D, González-Miguel J, Akhan O, Cretu CM, Vutova K, Tamarozzi F, Mariconti M, Brunetti E, Vola A, Fabiani M, Casulli A, Siles-Lucas M. Evaluation of the sensitivity and specificity of GST-tagged recombinant antigens 2B2t, Ag5t and DIPOL in ELISA for the diagnosis and follow up of patients with cystic echinococcosis. PLoS Negl Trop Dis 2020; 14:e0008892. [PMID: 33253168 PMCID: PMC7728171 DOI: 10.1371/journal.pntd.0008892] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2019] [Revised: 12/10/2020] [Accepted: 10/14/2020] [Indexed: 12/23/2022] Open
Abstract
Cystic echinococcosis (CE) is a neglected zoonotic disease caused by Echinococcus granulosus sensu lato. Diagnosis and monitoring of CE rely primarily on imaging while serology is used as a confirmatory test. However, imaging is not always conclusive and currently available serological assays have suboptimal sensitivity and specificity, lack standardization, and are not useful for patients´ follow-up. Seroassays for CE are usually based on hydatid fluid (HF), a complex, variable antigenic mixture, and cross-reactivity exists especially with alveolar echinococcosis. Recombinant proteins based on immunogenic antigens most abundant in HF, such as AgB1, AgB2 and Ag5, have been used to overcome these limitations. None of them so far showed potential to replace HF; however, their performance have been largely tested on a limited number of samples, and comparison of different antigens using the same cohort has been rarely performed. The combination of several immunogenic epitopes in a single recombinant protein could enhance test sensitivity. For the diagnosis and follow-up of patients with CE, we compared the performance of the crude HF, previously described recombinant 2B2t antigen, and GST-tagged version of 2B2t, and novel designed recombinants (GST-Ag5t and the GST-DIPOL chimera containing AgB1, AgBB2 and Ag5 epitopes) by IgG-ELISA format. Samples belong to a retrospective cohort of 253 well-characterized patients with CE, previously described for the evaluation of the 2B2t antigen, 92 patients with alveolar echinococcosis, and 82 healthy donors. The reference standard for CE diagnosis was the presence of a CE lesion as diagnosed by ultrasonography. The highest sensitivity was obtained with HF [86.7%, 95% confidence interval (CI): 81.2–91.0], followed by GST-2B2t (70.0%, 95% CI: 63.1–76.2), 2B2t (65.5%, 95% CI: 58.5–72.0), GST-Ag5t (64.5%, 95% CI: 57.5–71.1) and GST-DIPOL (63.1%, 95% CI: 56.0–69.7). The GST-2B2t had the best specificity (95.8%, 95% CI: 88.3–99.1) and the lowest cross-reactivity (38.7%, 95% CI: 27.6–50.6). Good response to treatment also correlated to negative test results in the GST-2B2t ELISA. While none of the tested recombinant antigen appears suitable to replace HF for the diagnosis of CE, GST-2B2t should be further explored as a confirmation test, based on its high specificity and low cross-reactivity, and for the follow-up after treatment in those patients with positive serology for this antigen. Cystic echinococcosis (CE) is a neglected parasitic zoonosis. Its diagnosis and follow-up require evaluation with imaging. Currently available serological tests are applied to confirm the diagnosis in doubtful cases, although having limitations in diagnostic accuracy, and they are not useful for patients’ follow-up. Seroassays for CE are usually based on hydatid fluid (HF) obtained from infected animals, with consequent problems of heterogeneity and low specificity. The use of semi-purified HF derivatives or recombinant antigens has been attempted to improve these aspects, but with an unacceptable loss in sensitivity. Most newly developed antigens have been tested on a limited number of samples, not always well characterized, and have been rarely compared using the same samples cohort. Here, we tested and compared three recombinant antigens (2B2t, GST-2B2t and GST-Ag5t), and a recombinant chimeric antigen (DIPOL) based on three highly immunogenic components of HF (B1, B2 and Ag5), in an attempt to increase the sensitivity of recombinant antigen-based seroassays for the diagnosis and follow-up of patients with CE. We found that GST-2B2t had higher sensitivity than the other antigenic preparations, but still not as high as HF, and that GST-2B2t and GST-DIPOL had statistically higher specificity than any of the other tested antigens. GST-2B2t also showed potential for the follow-up of patients with CE after drug treatment.
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Affiliation(s)
| | - Eylem Akdur
- Cukurova Univeristy, Department of Parasitology, Sarıçam/Adana, Turkey
| | - Raúl Manzano-Román
- Proteomic Unit, Center for Cancer Research, University of Salamanca, Campus Miguel de Unamuno, Salamanca
| | - Ana Hernández-González
- Instituto de Salud Carlos III, Centro Nacional de Microbiología, Majadahonda, Madrid, Spain
| | - María González-Sánchez
- Instituto de Recursos Naturales y Agrobiología de Salamanca (IRNASA-CSIC), Cordel de Merinas, Salamanca, Spain
| | - David Becerro-Recio
- Instituto de Recursos Naturales y Agrobiología de Salamanca (IRNASA-CSIC), Cordel de Merinas, Salamanca, Spain
| | - Javier González-Miguel
- Instituto de Recursos Naturales y Agrobiología de Salamanca (IRNASA-CSIC), Cordel de Merinas, Salamanca, Spain
| | - Okan Akhan
- Faculty of Medicine, Hacettepe University, Ankara, Turkey
| | - Carmen M. Cretu
- University of Medicine and Pharmacy, Colentina Clinical Hospital—Parasitology, Bucharest, Romania
| | - Kamenna Vutova
- Specialised Hospital of Infectious and Parasitic Diseases "Prof. Ivan Kirov", Department of Infectious, Parasitic and Tropical Diseases, Medical University, Sofia, Bulgaria
| | - Francesca Tamarozzi
- WHO Collaborating Centre for the epidemiology, detection and control of cystic and alveolar echinococcosis, Istituto Superiore di Sanità, Rome, Italy
| | - Mara Mariconti
- Department of Clinical Surgical Diagnostic and Paediatric Sciences, University of Pavia, Via Taramelli 5, Pavia, Italy
| | - Enrico Brunetti
- Department of Clinical Surgical Diagnostic and Paediatric Sciences, University of Pavia, and Division of Infectious and Tropical Diseases, San Matteo Hospital Foundation, Via Taramelli 5, Pavia, Italy
| | - Ambra Vola
- San Matteo Hospital Foundation, Via Taramelli 5, Pavia, Italy
| | - Massimo Fabiani
- Infectious Diseases Department, Istituto Superiore di Sanità, Rome, Italy
| | - Adriano Casulli
- WHO Collaborating Centre for the epidemiology, detection and control of cystic and alveolar echinococcosis, Istituto Superiore di Sanità, Rome, Italy
- European Reference Laboratory for Parasites (EURLP), Istituto Superiore di Sanità, Rome, Italy
| | - Mar Siles-Lucas
- Instituto de Recursos Naturales y Agrobiología de Salamanca (IRNASA-CSIC), Cordel de Merinas, Salamanca, Spain
- * E-mail:
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Antibodies Against Sarcocystis neurona , Neospora spp., and Toxoplasma gondii in Horses and Mules From the Northern Pantanal Wetland of Brazil. J Equine Vet Sci 2017. [DOI: 10.1016/j.jevs.2017.04.007] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
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Alvarado-Esquivel C, Howe DK, Yeargan MR, Alvarado-Esquivel D, Alfredo Zamarripa-Barboza J, Dubey JP. Seroepidemiology of Sarcocystis neurona and Neospora hughesi infections in domestic donkeys (Equus asinus) in Durango, Mexico. ACTA ACUST UNITED AC 2017; 24:27. [PMID: 28730993 PMCID: PMC5520387 DOI: 10.1051/parasite/2017030] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2017] [Accepted: 07/07/2017] [Indexed: 01/05/2023]
Abstract
There is currently no information regarding Sarcocystis neurona and Neospora hughesi infections in donkeys in Mexico. Here, we determined the presence of antibodies against S. neurona and N. hughesi in donkeys in the northern Mexican state of Durango. Serum samples of 239 domestic donkeys (Equus asinus) were assayed for S. neurona and N. hughesi antibodies using home-made enzyme-linked immunoassays; six (2.5%) of the 239 donkeys tested seropositive for S. neurona. The seroprevalence of S. neurona infection was comparable among donkeys regardless of their origin, health status, or sex. Multivariate analysis showed that seropositivity to S. neurona was associated with increased age (OR = 2.95; 95% CI: 1.11–7.82; p = 0.02). Antibodies to N. hughesi were found in two (0.8%) of the 239 donkeys. Both exposed donkeys were healthy, 3- and 6-year-old females. This is the first evidence of S. neurona and N. hughesi infections in donkeys in Mexico.
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Affiliation(s)
- Cosme Alvarado-Esquivel
- Biomedical Research Laboratory, Faculty of Medicine and Nutrition, Juárez University of Durango State. Avenida Universidad S/N, 34000 Durango, Mexico
| | - Daniel K Howe
- Department of Veterinary Science, M. H. Gluck Equine Research Center, University of Kentucky Lexington, Kentucky 40546-0099, USA
| | - Michelle R Yeargan
- Department of Veterinary Science, M. H. Gluck Equine Research Center, University of Kentucky Lexington, Kentucky 40546-0099, USA
| | - Domingo Alvarado-Esquivel
- Biomedical Research Laboratory, Faculty of Medicine and Nutrition, Juárez University of Durango State. Avenida Universidad S/N, 34000 Durango, Mexico
| | - José Alfredo Zamarripa-Barboza
- Healthcare Center No. 1 "Dr. Carlos León de la Peña". Secretary of Health, Boulevard de la Juventud S/N, 34000 Durango, Mexico
| | - Jitender P Dubey
- United States Department of Agriculture, Agricultural Research Service, Beltsville Agricultural Research Center, Animal Parasitic Diseases Laboratory, Building 1001, Beltsville, Maryland 20705-2350, USA
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Gutiérrez-Expósito D, García-Bocanegra I, Howe DK, Arenas-Montes A, Yeargan MR, Ness SL, Ortega-Mora LM, Álvarez-García G. A serosurvey of selected cystogenic coccidia in Spanish equids: first detection of anti-Besnoitia spp. specific antibodies in Europe. BMC Vet Res 2017; 13:128. [PMID: 28490374 PMCID: PMC5424396 DOI: 10.1186/s12917-017-1046-z] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2017] [Accepted: 05/04/2017] [Indexed: 11/15/2022] Open
Abstract
Background Equine besnoitiosis, caused by Besnoitia bennetti, and equine protozoal myeloencephalitis (EPM), caused by Sarcocystis neurona and Neospora hughesi are relevant equine diseases in the Americas that have been scarcely studied in Europe. Thus, a serosurvey of these cystogenic coccidia was carried out in Southern Spain. A cross-sectional study was performed and serum samples from horses (n = 553), donkeys (n = 85) and mules (n = 83) were included. An in-house enzyme-linked immunosorbent assay (ELISA) was employed to identify a Besnoitia spp. infection and positive results were confirmed by an a posteriori western blot. For Neospora spp. and Sarcocystis spp., infections were detected using in-house ELISAs based on the parasite surface antigens N. hughesi rNhSAG1 and S. neurona rSnSAG2/3/4. Risk factors associated with these protozoan infections were also investigated. Results Antibodies against Besnoitia spp., Neospora spp. and Sarcocystis spp. infections were detected in 51 (7.1%), 46 (6.4%) and 20 (2.8%) of 721 equids, respectively. The principal risk factors associated with a higher seroprevalence of Besnoitia spp. were the host species (mule or donkey), the absence of shelter and the absence of a rodent control programme. The presence of rodents was the only risk factor for Neospora spp. infection. Conclusions This study was the first extensive serosurvey of Besnoitia spp. infection in European equids accomplished by two complementary tests and gives evidence of the presence of specific antibodies in these populations. However, the origin of the infection is still unclear. Further parasite detection and molecular genotyping are needed to identify the causative Besnoitia and Neospora species. Finally, cross-reactions with antibodies directed against other species of Sarcocystis might explain the positive reactions against the S. neurona antigens. Electronic supplementary material The online version of this article (doi:10.1186/s12917-017-1046-z) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Daniel Gutiérrez-Expósito
- SALUVET, Animal Health Department, Faculty of Veterinary Sciences, Complutense University of Madrid, Ciudad Universitaria s/n, 28040, Madrid, Spain
| | - Ignacio García-Bocanegra
- Animal Health Department, Faculty of Veterinary Sciences, University of Cordoba-Agrifood Excellence International Campus (ceiA3), Cordoba, Spain
| | - Daniel K Howe
- Department of Veterinary Science, M.H. Gluck Equine Research Center, University of Kentucky, Lexington, KY, 40546-0099, USA
| | - Antonio Arenas-Montes
- Animal Health Department, Faculty of Veterinary Sciences, University of Cordoba-Agrifood Excellence International Campus (ceiA3), Cordoba, Spain
| | - Michelle R Yeargan
- Department of Veterinary Science, M.H. Gluck Equine Research Center, University of Kentucky, Lexington, KY, 40546-0099, USA
| | - SallyAnne L Ness
- Department of Clinical Sciences, College of Veterinary Medicine, Box 52, Cornell University, Ithaca, NY, 14853, USA
| | - Luis M Ortega-Mora
- SALUVET, Animal Health Department, Faculty of Veterinary Sciences, Complutense University of Madrid, Ciudad Universitaria s/n, 28040, Madrid, Spain
| | - G Álvarez-García
- SALUVET, Animal Health Department, Faculty of Veterinary Sciences, Complutense University of Madrid, Ciudad Universitaria s/n, 28040, Madrid, Spain.
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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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Ojo KK, Dangoudoubiyam S, Verma SK, Scheele S, DeRocher AE, Yeargan M, Choi R, Smith TR, Rivas KL, Hulverson MA, Barrett LK, Fan E, Maly DJ, Parsons M, Dubey JP, Howe DK, Van Voorhis WC. Selective inhibition of Sarcocystis neurona calcium-dependent protein kinase 1 for equine protozoal myeloencephalitis therapy. Int J Parasitol 2016; 46:871-880. [PMID: 27729271 DOI: 10.1016/j.ijpara.2016.08.003] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2016] [Revised: 08/01/2016] [Accepted: 08/05/2016] [Indexed: 01/12/2023]
Abstract
Sarcocystis neurona is the most frequent cause of equine protozoal myeloencephalitis, a debilitating neurological disease of horses that can be difficult to treat. We identified SnCDPK1, the S. neurona homologue of calcium-dependent protein kinase 1 (CDPK1), a validated drug target in Toxoplasma gondii. SnCDPK1 shares the glycine "gatekeeper" residue of the well-characterized T. gondii enzyme, which allows the latter to be targeted by bumped kinase inhibitors. This study presents detailed molecular and phenotypic evidence that SnCDPK1 can be targeted for rational drug development. Recombinant SnCDPK1 was tested against four bumped kinase inhibitors shown to potently inhibit both T. gondii (Tg) CDPK1 and T. gondii tachyzoite growth. SnCDPK1 was inhibited by low nanomolar concentrations of these BKIs and S. neurona growth was inhibited at 40-120nM concentrations. Thermal shift assays confirmed these bumped kinase inhibitors bind CDPK1 in S. neurona cell lysates. Treatment with bumped kinase inhibitors before or after invasion suggests that bumped kinase inhibitors interfere with S. neurona mammalian host cell invasion in the 0.5-2.5μM range but interfere with intracellular division at 2.5μM. In vivo proof-of-concept experiments were performed in a murine model of S. neurona infection. The experimental infected groups treated for 30days with compound BKI-1553 (n=10 mice) had no signs of disease, while the infected control group had severe signs and symptoms of infection. Elevated antibody responses were found in 100% of control infected animals, but only 20% of BKI-1553 treated infected animals. Parasites were found in brain tissues of 100% of the control infected animals, but only in 10% of the BKI-1553 treated animals. The bumped kinase inhibitors used in these assays have been chemically optimized for potency, selectivity and pharmacokinetic properties, and hence are good candidates for treatment of equine protozoal myeloencephalitis.
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Affiliation(s)
- Kayode K Ojo
- Department of Medicine, Division of Allergy and Infectious Disease, Center for Emerging and Reemerging Infectious Disease (CERID), University of Washington, Seattle, WA 98109, USA.
| | - Sriveny Dangoudoubiyam
- Department of Veterinary Pathobiology, College of Veterinary Medicine and Biomedical Sciences, Texas A&M University, College Station, TX 77843, USA
| | - Shiv K Verma
- United States Department of Agriculture, Agricultural Research Service, Beltsville Agricultural Research Center, Animal Parasitic Diseases Laboratory, Beltsville, MD 20705, USA
| | - Suzanne Scheele
- Center for Infectious Disease Research, Seattle, WA 98109, USA
| | - Amy E DeRocher
- Center for Infectious Disease Research, Seattle, WA 98109, USA
| | - Michelle Yeargan
- Department of Veterinary Science, University of Kentucky, Lexington, KY 40546, USA
| | - Ryan Choi
- Department of Medicine, Division of Allergy and Infectious Disease, Center for Emerging and Reemerging Infectious Disease (CERID), University of Washington, Seattle, WA 98109, USA
| | - Tess R Smith
- Department of Medicine, Division of Allergy and Infectious Disease, Center for Emerging and Reemerging Infectious Disease (CERID), University of Washington, Seattle, WA 98109, USA
| | - Kasey L Rivas
- Department of Medicine, Division of Allergy and Infectious Disease, Center for Emerging and Reemerging Infectious Disease (CERID), University of Washington, Seattle, WA 98109, USA
| | - Matthew A Hulverson
- Department of Medicine, Division of Allergy and Infectious Disease, Center for Emerging and Reemerging Infectious Disease (CERID), University of Washington, Seattle, WA 98109, USA
| | - Lynn K Barrett
- Department of Medicine, Division of Allergy and Infectious Disease, Center for Emerging and Reemerging Infectious Disease (CERID), University of Washington, Seattle, WA 98109, USA
| | - Erkang Fan
- Department of Biochemistry, University of Washington, Seattle, WA 98195, USA
| | - Dustin J Maly
- Department of Chemistry, University of Washington, Seattle, WA 98195, USA
| | - Marilyn Parsons
- Center for Infectious Disease Research, Seattle, WA 98109, USA; Department of Global Health, University of Washington, Seattle, WA 98195, USA
| | - Jitender P Dubey
- United States Department of Agriculture, Agricultural Research Service, Beltsville Agricultural Research Center, Animal Parasitic Diseases Laboratory, Beltsville, MD 20705, USA
| | - Daniel K Howe
- Department of Veterinary Science, University of Kentucky, Lexington, KY 40546, USA.
| | - Wesley C Van Voorhis
- Department of Medicine, Division of Allergy and Infectious Disease, Center for Emerging and Reemerging Infectious Disease (CERID), University of Washington, Seattle, WA 98109, USA; Department of Global Health, University of Washington, Seattle, WA 98195, USA.
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