Horses experimentally infected with Sarcocystis neurona develop altered immune responses in vitro

Sharon G. Witonsky, Siobhan Ellison, Jibing Yang, Robert M. Gogal, Heather Lawler, Yasuhiro Suzuki, Namalwar Sriranganathan, Frank Andrews, Daniel Ward, David S. Lindsay

Research output: Contribution to journalArticlepeer-review

16 Scopus citations


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 non-specific mitogens phorbol myristate acetate (PMA) and ionomycin (I) as soon as 2 days postinfection.

Original languageEnglish
Pages (from-to)1047-1054
Number of pages8
JournalJournal of Parasitology
Issue number5
StatePublished - Oct 2008

ASJC Scopus subject areas

  • Parasitology
  • Ecology, Evolution, Behavior and Systematics


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