Effect of dietary supplementation with Echinacea purpurea on vaccine efficacy against infection with Flavobacterium columnare in zebrafish (Danio rerio)

The effect of dietary Echinacea purpurea (EP) on the response of zebrafish (Danio rerio) to a Flavobacterium columnare vaccine was investigated. Two hundred D. rerio with an average weight of 290 ± 40 g were selected and fed different levels of E. purpurea (5 g kg⁻¹ diet - group 1, 10 g kg⁻¹ diet - group 2, 20 g kg⁻¹ diet - group 3, 30 g kg⁻¹ diet - group 4, and 0 g kg⁻¹ diet - group 5). Experimental feeding was begun 3 weeks prior to bath immunization and continued until the end of the experiment. Twenty-eight days after immunization the fish were challenged by bath immersion with F. columnare at a concentration of 1x106 CFU/ml. The relative percent survival of the experimental groups (1, 2, 3, 4 and 5) was 5.0, 6.0, 30.0, 36.0 and 5.0, respectively. In conclusion, diet supplementation with E. purpurea may effectively enhance the response of zebrafish to a F. columnare vaccine.