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

Abstract

Atlantic lumpfish (<i>Cyclopterus lumpus</i> L.) is used as a biological delousing agent for sea lice (<i>Lepeophtheirus salmonis</i> 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 <i>Aeromonas salmonicida</i> A‐layer types V and VI, <i>Vibrio anguillarum</i> serotype O1 and <i>Moritella viscosa</i> 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 <i>A. salmonicida</i> when compared to controls and the vegetable oil‐based vaccine group. The antibody response was poor against <i>V. anguillarum</i> and <i>M. viscosa</i> 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 <i>A. salmonicida</i>, but more work is required to identity optimal adjuvants.