Enrichment of outer membrane vesicles shed by Legionella pneumophila.

The production of outer membrane vesicles (OMVs) is a widespread phenomenon employed by bacteria to secrete cell envelope components into the environment. A contribution of Legionella pneumophila OMVs to the pathogenesis of Legionnaires' disease is likely due to the high number of virulence-related proteins in the vesicles. OMVs are isolated from the supernatant of liquid cultures of L. pneumophila. After low-speed centrifugation, residual bacteria and cell fragments are eliminated by passing the supernatant through a filter. OMVs are pelleted by ultracentrifugation and resuspended in buffer. The isolated OMVs can be analyzed for their molecular components and their interactions with host structures, bacterial cells, or surfaces.