(396c) Acetalated Dextran Microparticulate Subunit Anthrax Vaccine Formulated Using Coaxial Electrospray Preserves Toxin Neutralization and Enhances Protection
An alternative polymer particle fabrication method such as coaxial electrohydrodynamic spraying (electrospray) is amenable to overcoming these formulation barriers. Coaxial electrospray processes do not create harsh denaturing conditions and have demonstrated gentle encapsulation of proteins in model studies. Despite these promising results, coaxial electrospray methods have yet to be applied to notable therapeutic or vaccine applications utilizing polymer particles. In our current work, we use coaxial electrospray to formulate an anthrax vaccine. We efficiently and gently encapsulate the labile recombinant protein antigen (antigen from Bacillus anthracis, causative agent of anthrax) and Th1-skewing resiquimod adjuvant (toll-like receptor 7/8 agonist) either in separate particle sets or co-encapsulated in the same particle. We compare our electrospray formulations in parallel with particles fabricated by solvent evaporation and the FDA-approved anthrax vaccine (BioThrax). Our electrospray formulations administered parenterally lead to increased Th1-skewing antibody production, preserved toxin neutralization, and enhanced protection against an inhaled challenge of the clinically virulent B. anthracis Ames strain. These promising results support electrosprayâ??s potential to be a powerful platform technique for fabricating subunit vaccines and other protein-based drug delivery formulations.