Effects of iridovirus-like agent on the cell-mediated immunity in sheatfish (Silurus glanis)—an in vitro study

An iridovirus-like agent was tested for the first time in vitro on cell-mediated immunity in sheatfish (Silurus glanis). The influence of the iridovirus-like agent on pronephric macrophage metabolism was examined at two temperatures, 20 and 30°C, by studying the respiratory burst activity stimulated by phorbol myristate acetate as well as the proliferative ability of lymphocytes stimulated by concanavalin A (ConA) and lipopolysaccharide (LPS) measured by MTT assay. The results showed that the iridovirus-like agent decreased the macrophage activity at incubation temperatures of 20 and 30°C. The highest inhibitory effect was observed at 30°C. The proliferative ability of pronephric lymphocytes had a similar pattern. The results showed that applying a virus at the same time or after the mitogen at 20 and 30°C decreased the lymphocyte proliferation that was stimulated by either ConA or LPS. The highest suppressive effect was observed when virus was applied 14 h after the mitogen. This preliminary in vitro study demonstrated a strong suppressive influence of the iridovirus-like agent on pronephric macrophage and lymphocyte activity in sheatfish.