title: Augmentation of the antibody response of Atlantic salmon by oral administration of alginate-encapsulated IPNV antigens.
abstract: The objective of the present study was to assess the effect of alginate-encapsulated infectious pancreatic necrosis virus antigens in inducing the immune response of Atlantic salmon as booster vaccines. One year after intraperitoneal injection with an oil-adjuvanted vaccine, post-smolts were orally boosted either by 1) alginate-encapsulated IPNV antigens (ENCAP); 2) soluble antigens (UNENCAP) or 3) untreated feed (control). This was done twice, seven weeks apart. Sampling was done twice, firstly at 7 weeks post 1st oral boost and the 2nd, at 4 weeks after the 2nd oral boost. Samples included serum, head kidney, spleen and hindgut. Serum antibodies were analyzed by ELISA while tissues were used to assess the expression of IgM, IgT, CD4, GATA3, FOXP3, TGF-β and IL-10 genes by quantitative PCR. Compared to controls, fish fed with ENCAP had a significant increase (p<0.04) in serum antibodies following the 1st boost but not after the 2nd boost. This coincided with significant up-regulation of CD4 and GATA3 genes. In contrast, serum antibodies in the UNENCAP group decreased both after the 1st and 2nd oral boosts. This was associated with significant up-regulation of FOXP3, TGF-β and IL-10 genes. The expression of IgT was not induced in the hindgut after the 1st oral boost but was significantly up-regulated following the 2nd one. CD4 and GATA3 mRNA expressions exhibited a similar pattern to IgT in the hindgut. IgM mRNA expression on the other hand was not differentially regulated at any of the times examined. Our findings suggest that 1) Parenteral prime with oil-adjuvanted vaccines followed by oral boost with ENCAP results in augmentation of the systemic immune response; 2) Symmetrical prime and boost (mucosal) with ENCAP results in augmentation of mucosal immune response and 3) Symmetrical priming and boosting (mucosal) with soluble antigens results in the induction of systemic immune tolerance.
authors.affiliation: Department of Basic Sciences and Aquatic Medicine, Norwegian University of Life Sciences, Oslo, Norway.
authors.forename: Lihan
authors.initials: L
authors.lastname: Chen
authors.affiliation: EWOS Innovation AS, Sandnes, Norway; Department of Mechanical Engineering, University College London, London, United Kingdom.
authors.forename: Goran
authors.initials: G
authors.lastname: Klaric
authors.affiliation: EWOS Innovation AS, Sandnes, Norway.
authors.forename: Simon
authors.initials: S
authors.lastname: Wadsworth
authors.affiliation: Department of Mechanical Engineering, University College London, London, United Kingdom.
authors.forename: Suwan
authors.initials: S
authors.lastname: Jayasinghe
authors.affiliation: Department of Animal Science/Institute of Biotechnology, National Ilan University, Taipei, Taiwan.
authors.forename: Tsun-Yung
authors.initials: TY
authors.lastname: Kuo
authors.affiliation: Department of Basic Sciences and Aquatic Medicine, Norwegian University of Life Sciences, Oslo, Norway.
authors.forename: Øystein
authors.initials: Ø
authors.lastname: Evensen
authors.affiliation: Department of Basic Sciences and Aquatic Medicine, Norwegian University of Life Sciences, Oslo, Norway.
authors.forename: Stephen
authors.initials: S
authors.lastname: Mutoloki
mesh_terms: D000464:Alginates; D000818:Animals; D018175:Birnaviridae Infections / Q000276:immunology / Q000517:prevention & control / Q000662:veterinary*; D005393:Fish Diseases / Q000276:immunology / Q000517:prevention & control*; D020723:Glucuronic Acid; D006603:Hexuronic Acids; D007110:Immunity, Active / Q000276:immunology; D018928:Immunity, Mucosal / Q000276:immunology; D018061:Infectious pancreatic necrosis virus / Q000276:immunology*; D020317:Salmo salar / Q000276:immunology*; D014611:Vaccination; D014612:Vaccines
chemical_list: D000464:Alginates; D006603:Hexuronic Acids; D014612:Vaccines; D020723:Glucuronic Acid