Biomimetic Assembly of Spore@ZIF‐8 Microspheres for Vaccination

Vaccines have been one of the most powerful weapons to defend against infectious diseases for a long time now. Subunit vaccines are of increasing importance because of their safety and effectiveness. In this work, a Bacillus amyloliquefaciens spore@zeolitic imidazolate framework‐8 (ZIF‐8) vaccine platform is constructed. The ovalbumin (OVA) is encapsulated in the ZIF‐8 shells as a model antigen to form a spore@OVA@ZIF‐8 (SOZ) composite. The assembly of ZIF‐8 improves the loading content of OVA on the spores and provides OVA with long‐term protection. The SOZ composite enhances the immunization efficacy in multiple ways, such as facilitation of antigen uptake and lysosome escape, stimulation of dendritic cells to mature and secrete cytokines, boosting of antibody production and formation of an antigen depot. This platform shows several advantages including easy preparation, cost‐effectiveness, long life, convenience of transportation and storage, and no need for the cold chain. These findings may have promising implications for the rational design of safe and effective spore‐based composite vaccine platforms. A spore@ZIF‐8 vaccine platform is constructed via the biomimetic co‐mineralization of ZIF‐8 and antigen on the spore surface. It exhibits a good ability to induce the cellular and humoral immune responses in vitro and in vivo, including the activation of dendritic cells and the immunization of mice. This platform is easy to prepare, low cost, stable, effective, and biocompatible.