IMMUNE-RESPONSE IN THE SKIN OF EEL AGAINS T CYTOPHAGA-COLUMNARIS

This study was undertaken to investigate the immune response of eel An guilla japonica against formalin-killed cells (FKC) of Cytophaga colum naris. Eels were vaccinated by immersion or injection with FKC. The im mune response of the eels was studied 2 weeks after the vaccination. P rior to the challenge, the eel skin was damaged by wiping with alcohol absorbed cotton. For the challenge, the fish were immersed in a suspe nsion of C. columnaris at a density of 1.0 x 10(7) CFU/ml for 15 min. The survival rates of the immersion, injection and control groups were 60, 20 and 0% respectively. In the immersion group skin lesions appea red later than in the other groups, and infiltration of leucocytes in skin lesions occurred at 12 h after the challenge, while no such leuco cyte infiltration occurred in other groups. Inhibition activity of bac terial adhesion in the skin was demonstrated in the immersion fish. Ho wever, no agglutinating antibody was detectable in the serum or mucus of fish vaccinated by immersion. These results indicate that immersion immunization can activate the eel skin defense system.