Identification of surrogates of protection against yersiniosis in immersion vaccinated Atlantic salmon

• Published in: PLoS ONE
• Main Authors: Bridle, AR, Koop, BF, Nowak, BF
• Format: Article in Journal/Newspaper
• Language: English
• Published: Public Library of Science 2012
• Subjects: Agricultural and Veterinary Sciences; Fisheries Sciences; Aquaculture; Atlantic salmon
• Online Access: https://doi.org/10.1371/journal.pone.0040841; http://www.ncbi.nlm.nih.gov/pubmed/22808275; http://ecite.utas.edu.au/78646

Simple cost-effective bacterins are the earliest and most successfully used commercial vaccines in fish. In particular, thoseprepared from Yersinia ruckeri have proven effective at controlling Enteric Red Mouth Disease (ERM) and yersiniosis inrainbow trout and Atlantic salmon, respectively. However, the emergence of outbreaks of ERM caused by atypical biotypesof Y. ruckeri and reports of vaccine failure resulting in mass mortality of hatchery Atlantic salmon has reinvigorated interestin vaccines against fish bacterial diseases. Therefore the objective of this study was to identify surrogates of protectionagainst yersiniosis using cDNA microarray to characterise the response of host genes in the gills of unvaccinated andvaccinated Atlantic salmon challenged with Y. ruckeri . Differentially expressed genes were identified using two-way ANOVAand restricted to those with >2.5-fold change at P<0.05. Using cDNA microarray we identified the expression of 6 genes inresponse to infection and 4 genes associated with the protective host response to yersiniosis. Analysis by real-time PCRconfirmed that three immunologically relevant genes, namely a cathelicidin (47-fold) and a C-type lectin (19-fold) increasedin response to yersiniosis. Including collagenase (17-fold increase), an important tissue remodelling and repair enzyme,these genes represent 3 of 6 non-protective and/or pathological responses to yersiniosis. Genes associated with theprotective host response included an immunoglobulin gene and a selenoprotein that showed significant fold changes (15-fold increases each), highlighting the importance of antibody-mediated protection against yersiniosis. These findingsprovide much needed knowledge of the host-pathogen interaction in response to bacterial infection and immunisation infish. Significantly, we identified a transcriptional biosignature consisting of predominantly immune-relevant genes (14 upand 3 down-regulated) in the gills of Atlantic salmon after immersion vaccination and before bacterial challenge. Thisbiosignature may be used as a surrogate of protection and therefore as a predictor of vaccine success against yersiniosis.