Identification of Vibrio anguillarum Outer Membrane Vesicles Related to Immunostimulation in the Japanese Flounder, Paralichthys olivaceus

Abstract

We identified outer membrane vesicle (OMV) production in Vibrio anguillarum O1, a major fish pathogen that causes vibriosis, and characterized the OMVs. They were produced during normal growth, and were appeared as spherical vesicle fractions. The protein profile of the OMVs was similar to that of the outer membrane proteins, and the 38-kDa major protein band of OMV was identified as OmpU. The OMVs had enzyme activity of metalloprotease, hemolysin, and phospholipase, and stimulated the production of proinflammatory cytokines, such as TNF-α, IL-1β, and IL-6 when injected into the flounder.