Abstract
Natural killer (NK) activity of head kidney leucocytes of rainbow trout (Oncorhynchus mykiss) against IPN virus-infected and uninfected RTG-2 cells was examined by 51Cr release assay. Fish leucocytes were classified into four groups by cytotoxic activities : Type I, cytotoxic activity against uninfected RTG-2 cells was higher than that against infected cells; Type II, cytotoxic activity against infected cells was higher than that against uninfected cells; Type III, cytotoxic activity was low against both infected and uninfected cells; Type IV, cytotoxic activity was high against both cells. These results indicate that there are individual variations in NK activity of rainbow trout against allogenic and viral antigens.
