Harnessing bacterial biology and components for next-generation vaccine development.

Despite the success of global immunization, emerging pathogens necessitate flexible, scalable and multivalent vaccine platforms. This review explores the use of bacterial biology and constituent elements as versatile workhorses for next-generation vaccine design. Bacterial components including toxoids, polysaccharides, outer membrane vesicles, flagellin, and bacterial ghosts, function as both antigens and intrinsic adjuvants. In addition, lactic acid bacteria are increasingly being used as targeted mucosal delivery vehicles, offering the potential to establish immune defenses at sites of pathogen entry. By engaging pattern recognition receptors like Toll-like receptors and induction of signaling cascades, these platforms shape robust humoral, cellular, and mucosal immunity. Furthermore, bacterial components can shape immunological memory and the durability of immune responses through their capacity to activate innate immune sensing pathways. Some of these platforms represent mature technologies, while others are in ongoing progress. Integrating these components with synthetic biology allows for multivalent responses to evolving threats. Collectively, these approaches highlight the growing role of bacterial biology in shaping the future of broadly protective immunization strategies.