Effect of immunomodulator Roncoleukin on some indices of nonspecific immunity of arctic char

Health protection of aquacultured hydrobionts faces the problem of correcting immunodeficiency states of various genesis. Immunosuppression is associated with the development of opportunistic infections. In addition, the immuno-physiological status of farmed fish is directly related to fish production and, consequently, to the economic performance of aquaculture enterprises. The use of immune-correcting drugs in aquaculture is one of the new effective methods of controlling fish diseases. One such drug is Roncoleukin (recombinant interleukin-2), which provides the cellular component of adaptive immunity. Its use in fish farming has yielded positive results in sturgeon, carp and young salmon fish. In 2023 in the cold-water basin farm of IE Romanov (Leningrad Region) on three-year old Arctic char Salvelinus alpinus (Linnaeus, 1758) the effect of the preparation “Roncoleukin” on the indices of nonspecific immunity was evaluated. As a result of the experiment, the parameters characterizing the intensity of anti-infective immunity of fish bactericidal activity of blood serum, the level of C-reactive protein, the content of circulating nonspecific immune complexes and phagocytic activity of neutrophils were studied. The study showed a high level of bactericidal activity of blood serum in control and experimental fish and, as a consequence, the absence of immunodeficient individuals. The high index of neutrophil phagocytic activity in Arctic char fed Ronkoleikin indicates the stimulating effect of this drug on the mechanisms of cellular immunity. This indirectly confirms the higher content of immune complexes and the number of individuals with a positive level of C-reactive protein in the group of experimental fish.