Bacterial extracellular vesicle (BEV)

Bacterial extracellular vesicles (BEVs), including outer membrane vesicles (OMVs) from Gram-negative bacteria, are nano-sized, lipid-bilayer structures (20–400 nm) that serve as critical mediators in the communication between the microbiome and the host immune system (Nature Reviews Microbiology, 2020). These vesicles transport a diverse cargo of bacterial phospholipids, proteins, and nucleic acids, which function as pathogen-associated molecular patterns (PAMPs) recognized by host receptors. BEVs are primarily internalized by host dendritic cells (DCs), where they induce maturation and the expression of co-stimulatory molecules (Frontiers in Immunology, 2018). The lipid components, such as phospholipids, are processed and presented via CD1 molecules to specialized T cell subsets, while protein antigens are presented via MHC complexes, triggering robust adaptive immune responses (Nature Reviews Immunology, 2015). In the pharmaceutical industry, BEVs are being leveraged as potent vaccine platforms, as exemplified by the OMV-based Meningococcal B vaccine Bexsero, and as modular drug delivery vehicles for cancer immunotherapy (Journal of Extracellular Vesicles, 2021). Their ability to naturally adjuvant the immune system and traffic to lymphoid tissues makes them a significant focus for treating infectious diseases and oncology.

Other names

Outer membrane vesicleOMVBacterial vesicleMicrobiome-derived vesicleMembrane blebGram-negative outer membrane vesicle

Activation of host pattern recognition receptors (PRRs) such as TLRs and NLRs, and presentation of vesicle-associated lipid and protein antigens to T cells via CD1 and MHC molecules.