Development of a novel mucosal vaccine against strangles by supercritical enhanced atomization spray-drying of Streptococcus equi extracts and evaluation in a mouse model.

The study outlines a new approach to developing a vaccine against strangles, a highly infectious disease in horses, using a spray-drying technique. The created nanospheres successfully induced immune responses in a mouse model, suggesting the possibility of an effective strangles vaccine.

Understanding Strangles and the Need for a Vaccine

• Strangles is a highly contagious, sometimes lethal disease that affects the Equidae family, which comprises horses, donkeys, and zebras. The disease, caused by the bacterium Streptococcus equi, has global prevalence and has significant implications for animal health and the equine industry.
• Developing an effective vaccine against strangles is essential to control and potentially eradicate this infectious disease. Currently, available vaccines have inconsistencies in protection and might induce adverse reactions, thus the search for novel development methodologies is warranted.

The Supercritical Enhanced Atomization Spray-Drying Technique

• The research focuses on the development of a mucosal vaccine using a Supercritical Enhanced Atomization (SEA) spray-drying technique. This approach involves converting aqueous solutions containing S. equi extracts and chitosan, a natural polysaccharide, into nanospheres, without using any organic solvents.
• The SEA technique has several advantages, including potential for scale-up and productivity, and ability to obtain small and homogenous particles suitable for mucosal application.

Results and Implications

• The study used a mouse model to evaluate the immune response to the formulated vaccine. Results showed that the nanospheres elicited a balanced Th1 and Th2 response, indicated by equal concentrations of two types of antibodies—Immunoglobulin G2a (IgG2a) and Immunoglobulin G1 (IgG1). Alongside, Immunoglobulin A (IgA) production was also observed, which is a significant aspect of mucosal immunity.
• The balanced immune response suggested effective immunization against S. equi., making the SEA technique, and the resultant vaccine, a potential method to control strangles.
• This strategy could therefore be a feasible option for the production of a strangles vaccine. However, it is important to note that the research is in its preliminary stages, and further tests in larger animal models and ultimately in horses will be needed to confirm the effectiveness and safety of the proposed vaccine.