A novel Edwardsiella ictaluri E-ict-VL33 strain, a vaccine derived from the novel Edwardsiella ictaluri E-ict-VL33 strain, especially in immersion form and oral form, and a method for protecting fishes from the infection of Edwardsiella ictaluri , especially catfish, the method including a primary immersion immunization using immersion vaccine, and after an appropriate period, boosting by oral vaccination, resulting in a strong and long-lasting immunity for fishes.
1. A method for improving fish immunity against Edwardsiella ictaluri comprising: administering an Edwardsiella ictaluri vaccine composition to fish by immersion, as primary immunization; followed by first and second booster immunizations; by oral delivery, wherein the first booster immunization is at 8 to 21 days and the second booster immunization is at 101 to 107 days, wherein the Edwardsiella ictaluri vaccine comprises inactivated to Edwardsiella ictaluri E-ict-VL33 strain.
2. The method as recited in claim 1 , wherein before the Edwardsiella ictaluri vaccine composition is administered to fish by oral delivery, the vaccine composition is spray-coated on the outside of a feed, and then the coated feed is further sprayed with a oleaginous substance to obtain a feed coating by the vaccine composition.
3. The method as recited in claim 2 , wherein the oleaginous substance is at least one selected from the group consisting of: mineral oil, plant oil and animal oil.