Squalene containing solid lipid nanoparticles, a promising adjuvant system for yeast vaccines

Area of Science:

• Vaccinology
• Nanotechnology
• Immunology

Background:

• Potent adjuvants are crucial for subunit and single antigen vaccines to enhance immunogenicity.
• Squalene nanoemulsions (e.g., MF59®, AddaVax™) are established, safe, and effective human-use adjuvants.
• Adjuvants can decrease the number of immunizations and antigen dose required for vaccines.

Purpose of the Study:

• To develop novel squalene-containing solid lipid nanoparticles (SLNs) as vaccine adjuvants.
• To characterize the physical properties, particularly particle size, of the developed squalene SLNs.
• To evaluate the immunogenicity and biocompatibility of squalene SLNs compared to existing adjuvants.

Main Methods:

• Development and characterization of squalene-loaded solid lipid nanoparticles.
• Particle size analysis using dynamic and static light scattering.
• Differential scanning calorimetry (DSC) and 1H NMR for material interaction studies.
• Vaccine trial in a mouse model using a yeast-based vaccine against infectious bursal disease virus.

Main Results:

• Developed squalene SLNs exhibited a favored particle size range (120-170 nm), similar to AddaVax™.
• DSC and NMR studies indicated homogeneous distribution of liquid squalene within the solid lipid matrix.
• Squalene SLNs demonstrated excellent biocompatibility and immune-stimulating properties comparable to Freund's adjuvant and a commercial squalene nanoemulsion.

Conclusions:

• Squalene-containing solid lipid nanoparticles represent a promising new class of vaccine adjuvants.
• The developed squalene SLNs are sterilizable and can be stored as freeze-dried powder, enhancing stability and usability.
• These novel adjuvants show comparable efficacy and safety to established systems, offering potential for improved vaccine formulations.