Differential MHC-II, IL-8 and IgM genes expression in the liver, head Kidney and gill tissues of juvenile rainbow trout (Oncorhynchus mykiss) immunized by inactive trophonts of Ichthyophthirius multifiliis

The current study was designed to compare the genes expression levels of MHC-Pi, IL-8 and IgM in the head kidney and liver (central organs), as well as gill tissue (mucosal surface) of juvenile rainbow trout were immunized with gamma-irradiated and formalin inactive trophonts with/without alginate nanoparticles against Ichthyophthirius multifiliis. On day 20 after bath-immunization, fish in all the treatments, except negative control, was exposed to live trophonts. On the 30 th day, fish tissues were analyzed by real-time PCR. Results showed, the IL-8 expression up-regulated in the kidney, hepatic and gill of immunized fish with irradiated and formalin inactive trophonts plus alginate nanoparticles and non-immunized fish challenged with live trophonts (P<0.05). The MHC-II showed up-regulation in gill and kidney of immunized fish with irradiated and formalin inactive trophonts plus alginate nanoparticles and non-immunized fish challenged with live trophonts while hepatic MHC-Pi was up-regulated in immunized fish with formalin inactive trophonts plus alginate nanoparticles (P<0.05). A significant increase in the IgM expression was detected in gill of immunized fish with irradiated trophonts with/without alginate nanoparticles and formalin inactive trophonts plus alginate nanoparticles (P<0.05). The renal IgM showed upregulation in all of treatments (P<0.05). A significant increase in the hepatic IgM expression was in immunized fish via irradiated trophonts with/without alginate nanoparticles (P<0.05). These findings indicated that the higher expression of IgM, MHC-II and IL-8 at the gill, kidney and liver could prove the potential of the entire treatments to enhance both mucosal and systemic immune responses in immunized fish with gamma irradiated trophonts against I. multifiliis.

Automated summary

The study compared gene expression levels of MHC-Pi, IL-8, and IgM in rainbow trout vaccinated with gamma-irradiated trophonts against Ichthyophthirius multifiliis. Results showed up-regulation of these genes in vaccinated fish with the potential to enhance mucosal and systemic immune responses.