In this study, a mineral oil-based emulsion with a food-grade inexpensive saponin extract (OWq) and oil-based adjuvant that produces an emulsion after gentle mixing with an aqueous phase were tested for safety and immunological activity in swine vaccination.
In OWq, the saponin extract served as an emulsifier for stabilization of emulsion droplets and as an immunostimulant in the subunit vaccine.
Freshly prepared OWq emulsion had nanosize droplets in a range from 91 to 531 nm and low zeta potential (-51.7 mV), which provides electrostatic repulsion between the droplets and prevents their fast flocculation and coalescence.
However, a decrease in zeta potential value indicates lower colloidal stability over time in comparison with OWq emulsion.
Small subcutaneous bumps were observed at the injection sites of the OWq vaccine group, although they decreased in size significantly or disappeared towards the end of the experiment.
In addition, further investigation is required to confirm the level of protection of swine immunized with E2 protein and OWq saponin-based emulsion after the challenge with CSF virus.
Thus, OWq can be stored at least 180 days at different temperatures without dramatic changes in droplet size, creaming, or phase separation.
(a) Freshly prepared OWq emulsion had droplets within 90-600 nm size range, while oil-based adjuvant (OBA) mixed with PBS produced emulsion with droplets between 100 and 3000 nm.
Caption: Figure 3: Safety and immunological effect of OWq and OBA injected with E2 antigenic protein.