Abstract
The effects of Edwardsiella tarda lipopolysaccharide (LPS) on the immune response of eel were studied by determination of antibody titer and phagocytic activity of the blood and by determina-tion of survival rate to experimental challenge. Crude LPS and formalin killed cell (FKC) of E. tarda were injected twice intramuscularly in the eels. To compare the protective effect of the pre-parations, the eels were challenged with 2.4×107 cells/fish of live E. tarda, strain EF-1.
The agglutination antibody titer of both LPS and FKC immunized eels was high when com-pared to the controls. In vitro phagocytic activity of the total blood was high in both LPS and FKC immunization groups than that found in the control group, whereas the higher average ac-tivity was shown in the LPS immunization group. Only the eels immunized with LPS preparation showed survival to the experimental challenge. The results in the eel confirm the capacity of the LPS to increase not only the antibody titer, but also the level of phagocytosis and the protection to the infection.
