Immune response to Sarcocystis neurona infection in naturally infected horses with equine protozoal myeloencephalitis.

The study investigates the immune response in horses naturally infected with Sarcocystis neurona, the primary agent causing equine protozoal myeloencephalitis (EPM), a common neurologic disease in horses. Researchers have explored whether horses showing clinical signs of EPM indicate modified or suppressed immune responses when compared to healthy horses. They have also examined the influence of blood sample storage on these findings.

Research Background

• EPM is one of the most frequently diagnosed neurologic diseases in horses in the U.S, caused mainly by the parasitic protozoan Sarcocystis neurona.
• To date, understanding the protective or pathophysiologic immune response to S. neurona infection or the evolutionary development of EPM has been constrained.
• The study aims to identify if horses infected with S. neurona showing EPM symptoms have changed or suppressed immune responses when compared to neurologically normal horses.
• It’s crucial to also understand if blood sample storage methods can influence these findings.

Research Methods and Participants

• The study looked at two groups of horses – 20 clinically normal horses and 22 horses with EPM. EPM diagnosis was made based on the presence of S. neurona antibodies in the horses’ blood serum and/or cerebrospinal fluid (CSF) along with exhibiting clinical signs.
• The two groups were compared considering differences in immune cell subsets and their function.

Findings

• The results revealed that naturally infected horses had significantly higher percentages of CD4 T-lymphocytes and neutrophils in separated peripheral blood leukocytes compared to clinically normal horses.
• Leukocytes from naturally infected EPM horses had significantly lower proliferation responses to a non-antigen specific mitogen than clinically normal horses. These findings are currently being investigated to identify the role of CD4 T cells in disease and protection against S. neurona in horses and to discover the mechanism associated with suppressed in vitro proliferation responses.
• Overnight storage of blood samples was found to alter T lymphocyte phenotypes and viability among leukocytes, indicating that the handling and storage of samples could impact result accuracy.

Conclusion

• This study provides new insights into the immune response in horses naturally infected with S. neurona and raises important questions for further research. It demonstrated altered immune responses in horses with EPM and the possible effects of blood sample storage on these findings.
• Further research is required to clarify the function of CD4 T cells in the context of S. neurona infections and to unravel mechanisms behind the suppressed in vitro proliferation responses observed in the study.