Immune efficacy of Edwardsiella tarda ghosts vaccine for European eel (Anguilla anguilla)by 3 kinds of inoculation routes

Edwardsiellosis caused by Edwardsiella tarda is one of the most serious diseases in the eel culture industry.Bacterial ghosts,which have native surface antigenic structures and can induce humoral and cellular immune response,have become an important candidate of vaccine development.In present study,immune efficacy of E.tarda ghosts vaccine for European eel was detected in 3 kinds of inoculation routes.Results indicate that antibody titer of European eel shows significant increase after immunization with E.tarda ghost(ETG)and Formalin killed cell(FKC),but there is no significant difference between ETG group and FKC group.The relative protective survival(RPS)of ETG by intraperitoneal injection and immersion and oral administration are 75.0%,52.5%,37.5% respectively,is higher than FKC's 55.0%,40.0%,32.5% respectively.Moreover,the beginning of death time of eel immunization with ETG has a delay compared with FKC.Above results indicate that immune efficacy of ETG was superior to FKC.In particular RPS of ETG is 52.5% by oral administration.Considering easily operating and less stress,oral immunization of ETG has a favorable application prospect in preventing Edwardsiellosis of eel industry.