Bacteria-like particle bead complexes as an immunostimulatory platform for high-throughput vaccine antigen capture and delivery

Abstract

Abstract Vaccines are cited as the most cost-effective public health measure in controlling infectious diseases. Scalable and high-throughput platforms can accelerate vaccine discovery, which reduces the burden on human life, morbidity and health system resources. To expedite the antigen identification and production process during the first steps of vaccine development, we have developed a highly efficient bead capture system that allows for rapid antigen capture and delivery. This technology can be used in conjunction with protein microarrays to swiftly screen and identify antigens as potential vaccine candidates. Model antigens from Coxiella burnetii, a known biothreat and the etiological agent of Q fever, were chosen based on previous protein microarray data and expressed from plasmids containing a His-tag in a cell-free expression system. To demonstrate proof-of-concept, we used polystyrene beads with tris-NTA linkers to capture antigens from the mixture. The resulting antigen-conjugated beads were administered directly to C57BL/6 mice individually, multiplexed, and/or with an adjuvant cocktail of MPLA/CpG/squalene-in-water emulsion. Sera collected at regular intervals were screened against protein microarrays to monitor the dynamics and isotypes of the antibody response. Cytokine levels were assessed in antigen recall assays on splenocyte cell cultures through ELISPOT or by bead-based cytometric assay. Here we observed robust, durable and antigen-specific T cell and antibody responses. IgG isotypes and cytokine levels revealed that including adjuvants tuned the Th1/Th2 responses to a balanced profile. In vitro studies are currently underway to determine antibody functionality and neutralization potential.