Effect of continuous dietary administration of the Saccharomyces cerevisiae yeast, Δmnn9, on Pacific oyster (Crassostrea gigas) juveniles : immunological and histopathological findings after Vibrio coralliilyticus challenge

• Published in: Aquaculture
• Main Authors: Loor Mera, Alfredo, Bossier, Peter, Wang, Dongdong, De Bels, Lobke, Van Den Broeck, Wim, Nevejan, Nancy, Declercq, Annelies
• Format: Article in Journal/Newspaper
• Language: English
• Published: 2023
• Subjects: Agriculture and Food Sciences; Crassostrea gigas; Mutant yeast; Immunostimulant; Host tolerance; Vibrio infection; Histopathology; BINDING-PROTEIN LGBP; BETA-GLUCAN; IMMUNE-RESPONSE; GENE-EXPRESSION; MEDITERRANEAN MUSSEL; LIPOPOLYSACCHARIDE-BINDING; MYTILUS-GALLOPROVINCIALIS; MOLECULAR-CLONING; INFECTION PROCESS; CDNA CLONING; Pacific; Pacific oyster
• Online Access: https://biblio.ugent.be/publication/01H172R6HCAHWVSN8GQYRWK32H; http://hdl.handle.net/1854/LU-01H172R6HCAHWVSN8GQYRWK32H; https://doi.org/10.1016/j.aquaculture.2023.739644; https://biblio.ugent.be/publication/01H172R6HCAHWVSN8GQYRWK32H/file/01H172RHACQ0K1T64JAPCHCNA3

Yeast cells and their cell wall components, mainly β-glucans, are strong immunostimulants in bivalves, however, it remains unclear whether long-term administration of yeast contributes to prolonged activity of bivalve immune systems. Understanding these innate immune mechanisms is essential to establishing feeding strategies and disease prevention in hatcheries and nurseries. The present study examined the immunostimulatory effect of continuous dietary supply of the Saccharomyces cerevisiae mnn9 mutant (∆mnn9), which exhibits elevated exposure of β-glucans on the cell-wall surface, on Crassostrea gigas juveniles, and its protective effect against Vibrio coralliilyticus infections. In trial 1 the expression levels of immune-related genes were determined in oysters fed the ∆mnn9-containing diet 50A50Y (50% algae, 50% ∆mnn9; based on dry weight), compared to those fed the 100% algae-based diet (100A), after 6, 9, 12, 18, 24 h of feeding. In trial 2: the feeding period was expanded to 8 days, where the algal diet (100A) was provided every day, but substituted with 50A50Y for 0, 1, 2, 4, and 8 days (treatments 0D (control), 1D, 2D, 4D, and 8D, respectively) just before a Vibrio challenge, which was monitored for 7 days. Gene expression was measured before and 24-h after the Vibrio challenge. Histological analysis was performed on oysters on day 7 post-Vibrio challenge. Results showed that 50A50Y induced upregulation of interleukin 17–5 (CgIL17–5; 6 h), lysozyme (CgLys; 6 and 9 h), β-glucan-binding protein (CgβGBP; 18 h), and superoxide dismutase (CgSOD; 18 and 24 h) genes in juveniles (trial 1). Before the challenge, trial 2 demonstrated overexpression of CgSOD in animals from 1D, CgLys in those from 1D, 2D, and 4D, but not in oysters from 8D, compared to those from 0D. However, higher CgIL17–5 expression levels were observed in animals from 2D, 4D, and 8D, suggesting that inflammatory genes can remain inducible after 8 days of ∆mnn9 feeding. After the Vibrio challenge, a significantly higher survival was observed in ...