Fig. 3: Strategies to enhance oral vaccine efficacy through their interaction with gut microbiota.

A Design of β-glucan-encapsulated probiotics to induce mucosal immunity by modulating the gut microbiota. B An orally administered inulin gel increased the abundance of SCFA producers, such as Akkermansia, Lactobacillus, Roseburia, and their metabolites, which can benefit T-cell immunity. C Spore-based oral autonomous nanoparticles were fabricated to penetrate multiple barriers in the gastrointestinal tract. D Genetically engineered E. coli-derived OMVs that can cross the intestinal epithelial barrier and be internalized by APCs in the intestine to promote tumor antigen presentation can be used to construct oral tumor vaccines. Panel A was reproduced under the terms of the Creative Commons CC-BY 4.0 license¹⁰²; Copyright 2021, The Authors, published by the American Association for the Advancement of Science. Panel B was reproduced with permission¹⁰⁶; Copyright 2021, Springer Nature. Panel C was reproduced with permission¹²⁸; Copyright 2019, John Wiley and Sons. Panel D was reproduced with permission¹³⁹; Copyright 2022, Springer Nature.