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.