Effects of gamma-irradiated Ichthyophthirius multifiliis coated with calcium phosphate nanoparticles on immunological responses in rainbow trout (Oncorhynchus mykiss) skin mucus

Current study was performed to prepare a radiovaccine against Ichthyophthirius multifiliis, the causative agent of white spot in fresh water fishes. After irradiation with gamma ray, Ichthyophthirius multifiliis parasites were coated with calcium phosphate nanoparticles and then effects of prepared vaccine on non-specific immune system in rainbow trout skin mucus were evaluated. After 10-day adaption period, fish with mean weight 30 gram were distributed to 4 groups: Three groups were bath-vaccinated with gamma-irradiated Ichthyophthirius multifiliis coated with nano calcium phosphate, gamma-irradiated Ichthyophthirius multifiliis or nano calcium phosphate alone. In control group, no additives were used. On day 20, skin mucus from treated fish was analyzed for evaluating the innate immune parameters. Results showed that lysozyme and alkaline phosphatae activities and hemagglutination titer of fish treated with gamma-irradiated Ichthyophthirius multifilis coated with calcium phosphate nanoparticle were higher than other groups. But esterase activity in treatment groups did no change in comparison with the control group. It can be assumed that use of calcium phosphate nanoparticle formulated in gamma-irradiated Ichthyophthirius multifilis trophonts could enhance the innate immunity components in rainbow trout skin mucus. Further studies are needed to evaluate the effects of this radiovaccine on specific immune responses in rainbow trout.