Effect of temperature on production of skin mucus antibody in flounder(Paralichthys olivaceus)

We evaluated the effects of water temperature on the kinetics of skin mucus antibody in the flounder(Paralichthys olivaceus) using an indirect enzyme-linked immunosorbent assay(ELISA).The fish were held at 9℃,15℃,21℃,and 26℃ and given an intraperitoneal injection of inactivated lymphocystis disease virus(LCDV).The optical density(OD) of mucus antibody peaked 9 and 7 weeks after treatment in the groups held at 9℃ and 15℃,respectively(9℃: OD=0.179;15℃: OD=0.233).The OD increased most rapidly in fish held at 21℃,peak-ing at 0.316 during the 5th week.The OD was lower in fish held at 26℃ than at 21℃ and peaked(0.295) in the 5th week.We collected a sample of skin mucus from fish with the highest OD and extracted mucus Ig by ammo-nium sulfate precipitation.The mucus proteins from all four treatment groups yielded bands at 72 kD and 26 kD.Western blotting analysis revealed that the monoclonal antibody against serum Ig heavy chain could only recog-nize the 72 kD protein,which represents the heavy chain of skin mucus Ig.In conclusion,the most pronounced immune response was measured in fish that were maintained at their optimal temperature(21℃).In addition,the isolated mucus Ig may be used to study mucosal immunity in flounder.