The effects of dietary Immunogen® on innate immune response, immune related genes expression and disease resistance of rainbow trout (Oncorhynchus mykiss)

This study investigates the effects of prebiotic Immunogen® on lysozyme, TNFα and HSP70 gene expression in head kidney, humoral innate immune parameters and resistant to Aeromonas hydrophila of rainbow trout. 120 healthy rainbow trout (81.65 ± 1.49 g) were distributed in six fiberglass tanks assigned to two groups fed control or diet supplemented with 2 g kg−1 Immunogen® for 45 days. The results revealed that administration of Immunogen® significantly (P < 0.05) up regulated lysozyme and TNFα gene expression. HSP70 gene expression was significantly (P < 0.05) lower in Immunogen® fed fish at the end of trial. Humoral innate immune parameters (lysozyme activity, ACH50 and bactericidal activity) were significantly (P < 0.05) increased whether 15 or 45 days after feeding on Immunogen® supplemented diet. However, significant (P < 0.05) increase in agglutination antibody titer observed just after 45 days feeding on Immunogen®. Rainbow trout fed with 2 g kg−1 Immunogen® showed remarkably higher resistance against A. hydrophila (64.44% survival) compared to the control group (24.44% survival). These results confirm that Immunogen® can up regulates immune related genes expression, stimulates immune response that per se enhances disease resistance in rainbow trout.