Edwardsiella tarda outer membrane protein 1 is a virulence factor and a protective immunogen

Abstract

The bacterial outer membrane proteins are important components of bacterial cell. Edwardsiella tarda is a vital bacterial pathogen to a wide range of aquaculture animals. In this study, we examined the function of an outer membrane protein of E. tarda (named Omp1Et). Omp1Et was found to localize on the surface of E. tarda, and recombinant Omp1Et (rOmp1Et) was able to interact with flounder peripheral blood leukocytes. Compared to the wild type, the omp1Et knockout TX01Δomp1 was significantly reduced in motility, biofilm formation, attachment and invasion into host cells, dissemination in host tissues, and inducing host mortality. Furthermore, TX01Δomp1 was significantly impaired in the ability to survive under low pH and oxidizing conditions. When introduced into flounder as a subunit vaccine, rOmp1Et induced strong immune protection against E. tarda challenge. Taken together, these results indicate that Omp1Et is a surface-located virulence factor of E. tarda and rOmp1Et can induce effective immune-protection as a submit vaccine.