title: Oral vaccination of first-feeding Atlantic salmon, Salmo salar L., confers greater protection against yersiniosis than immersion vaccination.
abstract: Yersinia ruckeri is a ubiquitous pathogen of finfish capable of causing major mortalities in farmed fish stocks. It can be transmitted vertically from parent to progeny as well as horizontally in the water column from both clinically infected fish and asymptomatic carriers, and is consequently capable of infecting fish at early stages of development. Immunisation strategies that can protect small fry are therefore critical for the effective management of fish health, as is the ability to detect covertly infected fish. In this study, first-feeding Atlantic salmon fry (<0.5 g) were immunised either by oral administration of a microencapsulated Y. ruckeri vaccine formulation (0.38 g initial weight), or via immersion in bacterin suspension (0.26 g), with and without a booster immersion vaccination at 1g size. Protection in groups receiving only immersion immunisation did not differ significantly from untreated controls when challenged with Y. ruckeri at approximately 5 g size, while orally immunised fish were significantly better protected than untreated controls (F=4.38, df=4,10, P=0.026), with RPS varying between 29.4% (ORAL) and 51% (ORAL+DIP). A quantitative real-time PCR assay was used to successfully detect covertly infected fish among challenge survivors, indicating more than 50% of surviving fish in each group were infected with no significant differences between immunised fish and untreated controls.
authors.affiliation: Institute for Marine and Antarctic Sciences, University of Tasmania, Locked Bag 1370, Launceston, Tasmania 7250, Australia. Electronic address: bikramjit.ghosh@utas.edu.au.
authors.forename: Bikramjit
authors.initials: B
authors.lastname: Ghosh
authors.affiliation: Institute for Marine and Antarctic Sciences, University of Tasmania, Locked Bag 1370, Launceston, Tasmania 7250, Australia. Electronic address: Diem.Nguyen@utas.edu.au.
authors.forename: Thu D
authors.initials: TD
authors.lastname: Nguyen
authors.affiliation: Institute for Marine and Antarctic Sciences, University of Tasmania, Locked Bag 1370, Launceston, Tasmania 7250, Australia. Electronic address: philip.crosbie@utas.edu.au.
authors.forename: Philip B B
authors.initials: PBB
authors.lastname: Crosbie
authors.affiliation: Institute for Marine and Antarctic Sciences, University of Tasmania, Locked Bag 1370, Launceston, Tasmania 7250, Australia. Electronic address: b.nowak@utas.edu.au.
authors.forename: Barbara F
authors.initials: BF
authors.lastname: Nowak
authors.affiliation: Institute for Marine and Antarctic Sciences, University of Tasmania, Locked Bag 1370, Launceston, Tasmania 7250, Australia. Electronic address: andrew.bridle@utas.edu.au.
authors.forename: Andrew R
authors.initials: AR
authors.lastname: Bridle
mesh_terms: D000284:Administration, Oral; D000818:Animals; D000907:Antibodies, Bacterial / Q000097:blood; D001428:Bacterial Vaccines / Q000008:administration & dosage* / Q000627:therapeutic use; D002353:Carrier State / Q000382:microbiology / Q000662:veterinary; D004797:Enzyme-Linked Immunosorbent Assay; D005393:Fish Diseases / Q000517:prevention & control*; D056724:Immunity, Humoral; D020317:Salmo salar; D014611:Vaccination / Q000379:methods* / Q000662:veterinary; D015009:Yersinia Infections / Q000517:prevention & control / Q000662:veterinary*; D044124:Yersinia ruckeri
chemical_list: D000907:Antibodies, Bacterial; D001428:Bacterial Vaccines
keywords: First feeding; Fry; Microencapsulation; Mucosal vaccination; Oral vaccination; S. salar; Y. ruckeri