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International journal for parasitology2016; 46(13-14); 871-880; doi: 10.1016/j.ijpara.2016.08.003

Selective inhibition of Sarcocystis neurona calcium-dependent protein kinase 1 for equine protozoal myeloencephalitis therapy.

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.
Copyright © 2016 Australian Society for Parasitology. Published by Elsevier Ltd. All rights reserved.
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Publication Date: 2016-10-08 PubMed ID: 27729271PubMed Central: PMC5130624DOI: 10.1016/j.ijpara.2016.08.003Google Scholar: Lookup
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Summary

This research summary has been generated with artificial intelligence and may contain errors and omissions. Refer to the original study to confirm details provided. Submit correction.

The research article is about the identification of a protein in Sarcocystis neurona, a parasite that causes equine protozoal myeloencephalitis (EPM), a debilitating disease in horses. The researchers evaluated the efficacy of selective inhibitors of this protein, suggesting that these substances could be a new treatment approach for EPM.

Objective of the Study

  • The aim of this study was to identify SnCDPK1, a homologue of calcium-dependent protein kinase 1 (CDPK1) in Sarcocystis neurona – a parasite that causes equine protozoal myeloencephalitis, a devastating neurological disease in horses. The researchers wanted to assess whether selective SnCDPK1 inhibitors could potentially treat EPM.

Methods and Procedures

  • Four bumped kinase inhibitors were tested against recombinant SnCDPK1, these inhibitors were previously shown to efficiently inhibit T. gondii CDPK1 and T. gondii tachyzoite growth.
  • The researchers used thermal shift assays to confirm SnCDPK1 binding.
  • In vivo experiments were conducted using a murine model of S. neurona. Mice were divided into groups and treated with BKI-1553 for 30 days.

Findings of the Study

  • They found SnCDPK1 to be inhibited by low nanomolar concentrations of bumped kinase inhibitors.
  • Mammalian cells infected with S. neurona showed disruption of the host cell invasion process in the 0.5-2.5μM range of bumped kinase inhibitors. High concentrations of inhibitors (2.5μM) interfered with intracellular division of S. neurona.
  • In the in vivo model, mice that were treated for 30 days with the bumped kinase inhibitor BKI-1553 did not show signs of the disease.
  • Antibodies were found in all control (untreated) infected animals whereas only 20% of infected animals treated with BKI-1553 had elevated antibody responses. Also, parasites were found in brains of 100% of control infected animals, but only in 10% of treated animals.

Conclusion of the Study

  • Based on the results, the researchers concluded that targeting SnCDPK1 with bumped kinase inhibitors could be a promising therapeutic approach for treating equine protozoal myeloencephalitis.

Cite This Article

APA
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. (2016). Selective inhibition of Sarcocystis neurona calcium-dependent protein kinase 1 for equine protozoal myeloencephalitis therapy. Int J Parasitol, 46(13-14), 871-880. https://doi.org/10.1016/j.ijpara.2016.08.003

Publication

International journal for parasitology
ISSN: 1879-0135
NlmUniqueID: 0314024
Country: England
Language: English
Volume: 46
Issue: 13-14
Pages: 871-880
PII: S0020-7519(16)30211-9

Researcher Affiliations

Ojo, Kayode K
  • Department of Medicine, Division of Allergy and Infectious Disease, Center for Emerging and Reemerging Infectious Disease (CERID), University of Washington, Seattle, WA 98109, USA. Electronic address: ojo67kk@u.washington.edu.
Dangoudoubiyam, Sriveny
  • Department of Veterinary Pathobiology, College of Veterinary Medicine and Biomedical Sciences, Texas A&M University, College Station, TX 77843, USA.
Verma, Shiv K
  • United States Department of Agriculture, Agricultural Research Service, Beltsville Agricultural Research Center, Animal Parasitic Diseases Laboratory, Beltsville, MD 20705, USA.
Scheele, Suzanne
  • Center for Infectious Disease Research, Seattle, WA 98109, USA.
DeRocher, Amy E
  • Center for Infectious Disease Research, Seattle, WA 98109, USA.
Yeargan, Michelle
  • Department of Veterinary Science, University of Kentucky, Lexington, KY 40546, USA.
Choi, Ryan
  • Department of Medicine, Division of Allergy and Infectious Disease, Center for Emerging and Reemerging Infectious Disease (CERID), University of Washington, Seattle, WA 98109, USA.
Smith, Tess R
  • Department of Medicine, Division of Allergy and Infectious Disease, Center for Emerging and Reemerging Infectious Disease (CERID), University of Washington, Seattle, WA 98109, USA.
Rivas, Kasey L
  • Department of Medicine, Division of Allergy and Infectious Disease, Center for Emerging and Reemerging Infectious Disease (CERID), University of Washington, Seattle, WA 98109, USA.
Hulverson, Matthew A
  • Department of Medicine, Division of Allergy and Infectious Disease, Center for Emerging and Reemerging Infectious Disease (CERID), University of Washington, Seattle, WA 98109, USA.
Barrett, Lynn K
  • Department of Medicine, Division of Allergy and Infectious Disease, Center for Emerging and Reemerging Infectious Disease (CERID), University of Washington, Seattle, WA 98109, USA.
Fan, Erkang
  • Department of Biochemistry, University of Washington, Seattle, WA 98195, USA.
Maly, Dustin J
  • Department of Chemistry, University of Washington, Seattle, WA 98195, USA.
Parsons, Marilyn
  • Center for Infectious Disease Research, Seattle, WA 98109, USA; Department of Global Health, University of Washington, Seattle, WA 98195, USA.
Dubey, Jitender P
  • United States Department of Agriculture, Agricultural Research Service, Beltsville Agricultural Research Center, Animal Parasitic Diseases Laboratory, Beltsville, MD 20705, USA.
Howe, Daniel K
  • Department of Veterinary Science, University of Kentucky, Lexington, KY 40546, USA. Electronic address: daniel.howe@uky.edu.
Van Voorhis, Wesley C
  • 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. Electronic address: wesley@uw.edu.

MeSH Terms

  • Animals
  • Cell Line
  • Chlorocebus aethiops
  • Encephalomyelitis / drug therapy
  • Encephalomyelitis / parasitology
  • Female
  • Horse Diseases / drug therapy
  • Horse Diseases / parasitology
  • Horses
  • Interferon-gamma / genetics
  • Male
  • Mice
  • Mice, Knockout
  • Protein Kinase Inhibitors / chemistry
  • Protein Kinase Inhibitors / pharmacology
  • Protein Kinase Inhibitors / therapeutic use
  • Protein Kinases / drug effects
  • Rabbits
  • Sarcocystis / drug effects
  • Sarcocystis / enzymology
  • Sarcocystosis / drug therapy
  • Temperature
  • Toxoplasma / drug effects
  • Toxoplasma / enzymology

Grant Funding

  • R01 AI089441 / NIAID NIH HHS
  • R01 AI111341 / NIAID NIH HHS
  • R01 GM086858 / NIGMS NIH HHS
  • R01 AI097177 / NIAID NIH HHS
  • R01 HD080670 / NICHD NIH HHS

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Citations

This article has been cited 16 times.
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