Bacterial Outer Membrane Vesicles: An Emerging Tool in Vaccine Development, as Adjuvants, and for Therapeutic Delivery

Background: Advances in methods for engineering bacterial outer membrane vesicles are improving their utility as therapeutic and drug delivery agents. Specifically, bacterial vesicles have been investigated as adjuvants in vaccine formulations for some time. While success in this field has been demonstrated in animal models, especially in protection from infection by bacteria including Shigella, Acinetobacter, and Vibrio, further advances in bacterial vesicle engineering will make these materials more amenable as both vaccine components and drug delivery vehicles. Specifically, novel methods being developed to leverage natural bacterial processes in order to load specific cargo into bacterial vesicles as well as decorate their outer surface. Objective: This mini-review explores current literature focusing on research into the use of bacterial membrane vesicles in vaccine formulations as well as emerging technologies for engineering these structures, including cargo loading and surface modification. Conclusion: Engineered bacterial vesicles are emerging as novel reagents in the development of vaccines for bacterial pathogens and as adjuvant components of existing vaccine formulations. With continued advances in microbial engineering there is significant potential to develop bacterial vesicles as tools for not only vaccine development but also for use in the delivery of therapeutic compounds to targeted cells.