fig4

Figure 4. Strategies to engineer the membrane surface of BEVs. (A) Utilizing genetic engineering techniques to eliminate toxic molecules in BEVs membrane surface, fuse desired proteins with anchor protein or catcher, or displaying polysaccharide antigens on BEVs surface; (B) Using covalent (forming stable chemical bonds) or non-covalent (electrostatic interaction, hydrophobic insertion, receptor-ligand binding) reactions to coat antigens on BEVs surface; (C) Fusion with liposomes or natural cell membranes forms hybrid BEVs. BEVs: Bacterial extracellular vesicles; LPS: lipopolysaccharide; SpyTag: SpyTag peptide; SpyCatcher: SpyCatcher protein; O-PS: O-polysaccharide (O-antigen); PO-PS: pathogen-specific O-polysaccharide.