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Size-dependent resistance to amoebic gill disease in naive Atlantic salmon (Salmo salar)

Smith, AJ, Adams, MB ORCID: 0000-0002-5737-5474, Crosbie, PBB ORCID: 0000-0001-8856-1731, Nowak, BF ORCID: 0000-0002-0347-643X and Bridle, AR ORCID: 0000-0002-5788-1297 2022 , 'Size-dependent resistance to amoebic gill disease in naive Atlantic salmon (Salmo salar)' , Fish and Shellfish Immunology, vol. 122 , pp. 437-445 , doi:

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Amoebic gill disease, caused by the protozoan ectoparasite Neoparamoeba perurans, remains a significant threat to commercial Atlantic salmon aquaculture operations worldwide, despite partial control afforded by selective breeding and therapeutic intervention. Anecdotal reports from commercial producers suggest that historically, smaller Atlantic salmon smolts are more susceptible to AGD than larger smolts. Here, large (>350g) and small (N. perurans trophozoites L−1 without intervention. Progression and severity of AGD in challenged cohorts was evaluated through gill pathology, using gill score and histological examination, and quantification of gill-associated amoebae burden using qPCR. To determine the potential basis for differences in AGD susceptibility between cohorts, transcriptome analysis was conducted using RNA extracted from whole gill arches. Overall, the large Atlantic salmon cohort had significantly lower gill parasite burdens and reduced AGD-related gross pathology compared to the small cohort. Relative gill load of N. perurans appeared to be proportional to gill score in both size classes, with larger smolts typically observed to have comparatively reduced parasite burdens at a given gill score. Moreover, comparison between gene expression profiles of large and small smolts highlighted upregulation of genes consistent with elevated immune activity in large smolts. Combined, the results presented here provide strong evidence of size-dependent resistance to AGD in AGD-naive Atlantic salmon.

Item Type: Article
Authors/Creators:Smith, AJ and Adams, MB and Crosbie, PBB and Nowak, BF and Bridle, AR
Keywords: Neoparamoeba perurans, quantitative PCR, transcriptome, gene expression, Immune response, farmed Atlantic salmon
Journal or Publication Title: Fish and Shellfish Immunology
Publisher: Academic Press Ltd Elsevier Science Ltd
ISSN: 1050-4648
DOI / ID Number:
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© 2022 Elsevier Ltd. All rights reserved.

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