Penetration of equine leukocytes by merozoites of Sarcocystis neurona.

The study investigates how merozoites, the stage of the Sarcocystis neurona parasite, can penetrate and survive within horse blood cells. The research explores the possibility that infected blood cells could act as carriers, allowing the parasite to cross into the central nervous system and cause neurological diseases in horses.

Objective of the Study

• The main aim of the study was to examine the capacity of Sarcocystis neurona merozoites to penetrate and survive within horse leukocytes (white blood cells).
• The researchers hypothesized that the parasite could be using infected leukocytes as a transport mechanism to the central nervous system, facilitating the onset of severe neurological diseases in horses.

Methodology and Observations

• The researchers cultured merozoites with equine leukocytes and observed the interaction.
• Within 5 minutes of co-culture, the merozoites penetrated the equine leukocytes.
• The leukocytes that were most commonly infected were usually monocytes, a type of white blood cell.
• Infected leukocytes were present through to the end of the examination period at 3 days, with up to three merozoites inhabiting a single monocyte.
• No development to schizont stages (the asexual stage of the parasite where it multiples) was evident in these infected cells.

Findings and Interpretations

• Based on the experimental results, the researchers postulate that the S. neurona merozoites can cross the blood-brain barrier by hiding inside leukocytes.
• Once inside the central nervous system, these merozoites could potentially exit the leukocytes and invade more cells, causing an inflammatory condition of the central nervous system known as encephalitis.
• All observed stages of the merozoite’s lifespan within the leukocytes took place in the host cell’s cytoplasm.

Significance of the Study

• The results of this study offer a possible explanation for the mechanism by which S. neurona parasites cross into the central nervous system in horses, highlighting the role of leukocytes as potential transport vessels.
• Understanding this mechanism could provide insight into how severe neurological diseases in horses, caused by this parasite, can be controlled and treated.