Primary and secondary antibody responses to immunisation with single antigens and Aeromonas salmonicida bacterin in Atlantic salmon, Salmo salar L.

• Main Authors: Manning, A. J., Dacanay, A., Johnson, S. C.
• Format: Other/Unknown Material
• Language: English
• Published: Aquaculture Association of Canada 2008
• Subjects: Tapa; Atlantic salmon; Salmo salar
• Online Access: https://nrc-publications.canada.ca/eng/view/object/?id=46f10f17-8dad-45c9-8ea7-6d848c3861de; https://nrc-publications.canada.ca/fra/voir/objet/?id=46f10f17-8dad-45c9-8ea7-6d848c3861de

An important property of an effective vaccine is its ability to establish immunological memory. In this 25 week study, we compared primary and secondary antibody responses of individually tagged juvenile salmon immunised with three non-adjuvanted preparations: i) recombinant TapA protein, an A. salmonicida pilus protein that is a putative thymus-dependent antigen with memory-inducing potential; ii) lipopolysaccharide (LPS) purified from A. salmonicida (A449), a thymus-independent antigen of poor memory-inducing potential; and, iii) bacterin, the basis of most commercial vaccines, a suspension of formalin-killed A. salmonicida (A449) cells cultured under ironrestricted conditions. ELISA results showed that primary antibody responses to rTapA or LPS were synchronized while bacterin responses were individually variable. Immunological memory followed secondary immunisation with rTapA, but not LPS, which suggests that thymus-dependent and thymus-independent designations apply to these antigens. The immune response of bacterin-immunised fish to A. salmonicida lacked evidence of memory and was dominated by antibodies produced against LPS. This suggests that bacterin-based vaccines, while capable of producing short-term immunity to A. salmonicida, may not be able to stimulate immunological memory for adequate long-term antigen recognition. The study highlights the need to ensure that bacterin preparations are supplemented with thymus-dependent antigens capable of stimulating immunological memory. Peer reviewed: No NRC publication: Yes