Immunization of rainbow trout, <i>Salmo gairdneri</i> Richardson, against vibriosis: comparison of an extract antigen with whole cell bacterins by oral and intraperitoneal routes

Abstract

Abstract. An extract vaccine against Vibrio anguillarum was compared with other vaccine preparations when administered to rainbow trout intraperitoneally or orally on food. Intraperitoneal vaccination resulted in virtually 100% protection within two weeks whereas oral vaccination gave a maximum protection of 50–70% after eight weeks. When administered intraperitoneally the extract performed better than formalin killed cells but when administered orally formalin killed cells were better. The addition of alum as adjuvant enhanced the response to antigen administered by both routes. Serum agglutinin litres after oral vaccination were low and variable but after intraperitoneal injection they reached a consistent peak of 64. As the response to oral vaccination was so low it was not possible to relate agglutinin titre to protection in a quantitative relationship.