Simple method for the preparation of antigen emulsions for immunization

Area of Science:

• Immunology and Vaccine Development
• Biophysical Chemistry and Emulsion Science

Background:

• Traditional methods for preparing antigen-in-adjuvant emulsions for immunization can be time-consuming and inconsistent.
• The widely used double-hubbed needle method for creating water-in-oil emulsions presents challenges in reproducibility and efficiency.

Purpose of the Study:

• To develop and evaluate a novel, rapid, safe, and reliable method for preparing water-in-oil emulsions of water-soluble antigens in an adjuvant oil phase.
• To compare the new stepwise addition method with the established double-hubbed needle method regarding emulsification time, antigen release rate, and immunogenicity.

Main Methods:

• A new emulsification technique utilizing a three-way 'T' connector and disposable syringes for stepwise addition of the aqueous phase into the oil phase.
• Comparative analysis of emulsification time, antigen release kinetics, emulsion stability, viscosity, and immunogenic response (antibody titers via ELISA) between the new method and the double-hubbed needle method.
• Tested antigens included bovine serum albumin and transferrin.

Main Results:

• The stepwise addition method significantly reduced emulsification time (6.1 ± 2.1 min) compared to the double-hubbed needle method (41.1 ± 28.0 min) (P < 0.001).
• The new method consistently produced water-in-oil emulsions, whereas the double-hubbed needle method failed approximately 20% of the time.
• Antigen release was significantly slower (P < 0.01) with the stepwise addition method, with no significant differences in emulsion viscosity, stability, or immunogenicity (antibody titers) between the two methods.

Conclusions:

• The stepwise addition method offers a superior approach for preparing antigen emulsions, characterized by increased speed, enhanced reproducibility, and improved safety due to reduced pressure requirements.
• The slower antigen release observed with the stepwise addition method may offer advantages for sustained immune responses.
• This method is recommended as the preferred technique for preparing antigen emulsions for immunization purposes.