A Method for Producing Protein Nanoparticles with Applications in Vaccines.

Area of Science:

• Bioconjugation Chemistry
• Nanotechnology
• Vaccine Development

Background:

• Reliable synthesis of protein conjugate vaccines is crucial for preclinical and clinical studies.
• Existing methods may lack reproducibility or broad applicability.
• There is a need for adaptable nanoparticle synthesis for diverse protein antigens.

Purpose of the Study:

• To describe a practical and reproducible method for synthesizing conjugated protein nanoparticles.
• To demonstrate the general applicability of this method across various protein structures.
• To validate the efficacy of these nanoparticles as potential vaccine candidates.

Main Methods:

• Utilized thioether (thiol-maleimide) cross-linking chemistry for nanoparticle synthesis.
• Created single-component nanoparticles from malarial antigens (AMA1, CSP, Pfs25).
• Developed two-component nanoparticles by cross-linking antigens with the carrier protein EPA (Pseudomonas aeruginosa exotoxin A).

Main Results:

• Synthesized protein nanoparticles with average molar masses (Mw) from 487 kDa to 3,420 kDa and hydrodynamic radii (Rh) from 12.1 nm to 38.3 nm.
• Confirmed that protein antigenic properties and secondary structures remained largely intact post-conjugation, evidenced by unchanged far UV circular dichroism spectra.
• Demonstrated successful binding to conformation-dependent monoclonal antibodies.
• Showcased enhanced antigen-specific antibody levels in mice vaccinated with Pfs25 or CSP-EPA nanoparticles compared to monomeric antigens.

Conclusions:

• The described thioether cross-linking method provides a reliable and reproducible platform for protein nanoparticle synthesis.
• These protein nanoparticles maintain protein integrity and immunogenicity, showing promise as effective vaccine formulations.
• The method's general applicability supports its potential for developing diverse protein conjugate vaccines for various diseases.