Bacterial outer membrane vesicles (OMVs) are secreted structures that play a critical role in Gram-negative pathogen-host interactions. These vesicles, derived from the outer membrane of growing bacteria, serve as vehicles for transporting proteins, lipids, and virulence factors to host cells. OMVs are involved in colonization, virulence, immune modulation, and toxin delivery. They are formed through a process involving the outer membrane bulging and pinching off, and they contain a subset of outer membrane proteins and periplasmic components. OMVs are distinct from other secretion systems and are a key mechanism for pathogens to deliver active virulence factors to host cells. OMVs are produced by both pathogenic and nonpathogenic Gram-negative bacteria, including Escherichia coli, Shigella, Neisseria, Pseudomonas aeruginosa, and Helicobacter pylori. They contain adhesins, toxins, and immunomodulatory compounds that facilitate bacterial binding, invasion, and immune modulation. OMVs can also contribute to bacterial survival by reducing toxic compounds and aiding in phage resistance. The composition and production of OMVs are influenced by environmental factors, bacterial growth phase, and the presence of virulence factors. OMVs are involved in various host-pathogen interactions, including the dissemination of pathogens, modulation of immune responses, and the transfer of genetic material between bacteria. They can mediate coaggregation of bacteria, enabling biofilm formation and colonization. OMVs also play a role in the internalization of pathogens into host cells, with some toxins being delivered directly into the cytosol. The ability of OMVs to deliver toxins and modulate immune responses makes them potent virulence factors. The formation of OMVs is influenced by bacterial growth, the integrity of the peptidoglycan layer, and the presence of specific genes. The composition of OMVs can be altered by environmental conditions, such as iron availability, oxygen stress, and the presence of antibiotics. OMVs can also be used by bacteria to gain a competitive advantage over other bacteria by delivering lytic enzymes or facilitating the transfer of beneficial genetic material. Overall, OMVs are a critical component of Gram-negative bacterial virulence, enabling the dissemination of virulence factors, immune modulation, and interaction with host cells. Understanding the mechanisms of OMV formation and their role in host-pathogen interactions is essential for developing strategies to combat bacterial infections.Bacterial outer membrane vesicles (OMVs) are secreted structures that play a critical role in Gram-negative pathogen-host interactions. These vesicles, derived from the outer membrane of growing bacteria, serve as vehicles for transporting proteins, lipids, and virulence factors to host cells. OMVs are involved in colonization, virulence, immune modulation, and toxin delivery. They are formed through a process involving the outer membrane bulging and pinching off, and they contain a subset of outer membrane proteins and periplasmic components. OMVs are distinct from other secretion systems and are a key mechanism for pathogens to deliver active virulence factors to host cells. OMVs are produced by both pathogenic and nonpathogenic Gram-negative bacteria, including Escherichia coli, Shigella, Neisseria, Pseudomonas aeruginosa, and Helicobacter pylori. They contain adhesins, toxins, and immunomodulatory compounds that facilitate bacterial binding, invasion, and immune modulation. OMVs can also contribute to bacterial survival by reducing toxic compounds and aiding in phage resistance. The composition and production of OMVs are influenced by environmental factors, bacterial growth phase, and the presence of virulence factors. OMVs are involved in various host-pathogen interactions, including the dissemination of pathogens, modulation of immune responses, and the transfer of genetic material between bacteria. They can mediate coaggregation of bacteria, enabling biofilm formation and colonization. OMVs also play a role in the internalization of pathogens into host cells, with some toxins being delivered directly into the cytosol. The ability of OMVs to deliver toxins and modulate immune responses makes them potent virulence factors. The formation of OMVs is influenced by bacterial growth, the integrity of the peptidoglycan layer, and the presence of specific genes. The composition of OMVs can be altered by environmental conditions, such as iron availability, oxygen stress, and the presence of antibiotics. OMVs can also be used by bacteria to gain a competitive advantage over other bacteria by delivering lytic enzymes or facilitating the transfer of beneficial genetic material. Overall, OMVs are a critical component of Gram-negative bacterial virulence, enabling the dissemination of virulence factors, immune modulation, and interaction with host cells. Understanding the mechanisms of OMV formation and their role in host-pathogen interactions is essential for developing strategies to combat bacterial infections.