ORAL VACCINATION AGAINST YERSINIA RUCKERI: BIOMARKERS OF PROTEIN OXIDATION IN THE HEPATIC TISSUE OF RAINBOW TROUT (ONCORHYNCHUS MYKISS WALBAUM)

The aim of this study was to evaluate the one-month effect of oral vaccination against Yersinia ruckeri based on oxidative stress biomarkers in the hepatic tissue of rainbow trout (Oncorhynchus mykiss Walbaum). The vaccine consisted of three strains of Y. ruckeri (serotype O1) obtained from rainbow trout from different farms where fish showed clinical signs of enteric redmouth disease. The vaccine was produced at the Department of Fish Diseases, National Veterinary Research Institute in Pulawy (Poland) according to the process covered by patent no. P.428259. The concentrated vaccine was added to the fish feed. Treatment was administered three times at one-day intervals. Livers were sampled one month after immunisation. Our results show that immunisation with the anti-Yersinia vaccine did not alter the liver tissue of rainbow trout. aldehydic and ketonic derivatives of oxidatively modified proteins (OMP) were not significantly altered in the hepatic tissue of vaccinated fish prior to immunisation. One month after immunisation, the levels of ketonic derivatives of OMP in the hepatic tissue of untreated trout were reduced compared to the untreated group before immunisation. Similar to the untreated groups, the levels of ketonic derivatives of OMP in the hepatic tissue of the vaccinated group one month after immunisation were reduced compared to the vaccinated group before immunisation. A statistically non-significant decrease in the total antioxidant capacity (TAC) levels was observed between the values obtained in the untreated and vaccinated groups before vaccination and one month after vaccination. Understanding the role of oxidative stress in the tissues of vaccinated trout has important implications for understanding the complex physiological changes that occur during vaccination, and also for improving aquaculture practices to maximise tissue growth and health of vaccinated trout.