Studies on the antibody response and side effects after intramuscular and intraperitoneal injection of Atlantic lumpfish (Cyclopterus lumpus L.) with different oil-based vaccines.

Atlantic lumpfish (Cyclopterus lumpus L.) is used as a biological delousing agent for sea lice (Lepeophtheirus salmonis K.) infestations in Norwegian aquaculture. Here, we present a study on the antibody response and vaccine side effects after intramuscular and intraperitoneal injection of lumpfish with two vaccines. Both vaccines contained bacterial antigens from atypical Aeromonas salmonicida A-layer types V and VI, Vibrio anguillarum serotype O1 and Moritella viscosa sp., but one vaccine contained a vegetable oil-based adjuvant, while the other contained a mineral oil-based adjuvant. Intramuscular injection of the mineral oil-based vaccine caused a high acute mortality of fish within 48 hr after immunization. Intraperitoneal injection of the mineral oil-based vaccine resulted in a lower severity of intra-abdominal side effects than the vegetable oil-based vaccine. Intramuscular injection of the mineral oil-based vaccine resulted in a significantly higher antibody response against A. salmonicida when compared to controls and the vegetable oil-based vaccine group. The antibody response was poor against V. anguillarum and M. viscosa for all groups. Our results indicate that intramuscular injection of oil-based vaccines might be feasible for providing immunological protection for Atlantic lumpfish against bacterial diseases, especially atypical A. salmonicida, but more work is required to identity optimal adjuvants.