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

The research investigates how horses infected with Sarcocystis neurona, a parasite causing a common neurologic disease called Equine protozoal myeloencephalitis (EPM), have altered immune responses. The study particularly focuses on whether the horses’ immunity is suppressed post-infection.

Objectives and Methodology

• The main goal of the study was to understand the behaviors of the immune system in horses that were experimentally infected with S. neurona, especially focusing on whether their immune responses were suppressed.
• Thirteen horses, all tested negative for S. neurona antibodies in their serum and cerebrospinal fluid (CSF), were used in the experiment. They were divided into two groups: control (5 horses) and infected (8 horses).
• The researchers performed neurologic exams and CSF analyses before and after S. neurona infection. They recorded and studied several immune parameters before the infection and at different stages after the infection.

Findings

• All eight horses that were experimentally infected with S. neurona developed clinical signs that were consistent with EPM and tested positive for S. neurona antibodies in their serum and CSF.
• The study revealed that both the infected and control horses experienced an increase in the percentage of B cells at the 28th day post-infection, with the increase being significant.
• The infected horses demonstrated a significant drop in proliferation responses as early as 2 days post-infection. The proliferation responses were measured by thymidine incorporation to nonspecific mitogens phorbol myristate acetate (PMA) and ionomycin (I).

In essence, this study provides meaningful insights into the altered immune response in horses following S. neurona infestation, potentially paving the way for new therapeutic strategies for EPM.