Evaluation of immune responses in horses immunized using a killed Sarcocystis neurona vaccine.

The research conducted here looks into immune responses in horses after they were vaccinated with a commercially available, inactivated Sarcocystis neurona vaccine. This was measured through the development of antibodies in the horses and their skin’s response to further testing, suggesting the cellular immunity has been provoked.

Objective of the Research

• The researchers intended to evaluate how effective a commercially available Sarcocystis neurona vaccine is in immunizing horses against S. neurona infections. Sarcocystis neurona is a parasite that can cause severe neurological disease in horses.

Methodology of the Research

• The study involved vaccinating clinically healthy horses with the S. neurona vaccine, which had been killed (inactivated) to ensure it would not cause disease in the horses.
• The researchers monitored the horses for signs of an immune response. This included tracking the development of anti-S. neurona IgG antibodies, which are produced by the immune system to fight off this specific infection. Additionally, the researchers carried out intradermal skin testing. This test involved injecting a small amount of the S. neurona allergen under the horse’s skin and observing for a local inflammatory reaction — a sign of immune response.

Results

• The results suggest that the vaccinated horses developed cellular immunity against S. neurona, evidenced by the observed antibody production and positive skin inflammatory responses.

On-going Research and Future Directions

• In order to fully assess the efficacy and safety of this vaccine, larger-scale studies are currently being performed in real-world conditions.
• In the future, the researchers aim to further test the vaccine’s ability to immunize horses against S. neurona by conducting experimental challenges. This involves deliberately exposing vaccinated horses to the S. neurona parasite to see whether or not they get infected. However, this can only be carried out once a reliable equine model of S. neurona encephalitis has been established that will allow for the re-growth of the pathogen after the experimental exposure.