The inflammatory, genotoxicity, antioxidants, and pathological response to ectoparasite infection of cultured Nile tilapia

Ectoparasites Dactylogyrus spp. mainly infest fish gills and severely damage the host’s gill tissues. Correspondingly, the explanation of the interaction of fish with Dactylogyrus spp. infection is still insufficient. The present study describes the changes in hemato-biochemical, immune, antioxidant, genotoxic, and pathological indices response of Nile tilapia (Oreochromis niloticus) severely (n > 50), mildly infected (n = 1–50), and uninfected with Dactylogyrus spp. Data showed the adverse effect of hemato-biochemical indices in infected fish compared to uninfected, notably in severely infected O. niloticus. Compared to uninfected fish, there is a significantly decreased serum lysozyme and complement C3 and increased IgM and phagocytic activity along with significant upregulation of (COX-2), (IL-1β), (TNF-α), and (IL-10) genes in infected fish partially, in severely infected fish. Concisely, indices of antioxidants in the liver and gills marked an increased level of MDA in the infected fish compared to the uninfected fish. Conversely, levels of SOD, CAT, and GSH were decreased significantly with damaged DNA in the gills and liver of infected groups, particularly in severely infected (P < 0.05). Histopathologically investigating livers and gills in infected Nile tilapia indicated damaging and degenerative alterations, particularly with severe infection. Findings showed that Dactylogyrus spp.–infected Nile tilapia were effective in improving our knowledge of fish-pathogen interactions, which may be essential for fish defense against parasite infection.