Flagellin is the major component of the flagellum, and a ligand for Toll-like receptor 5. As reported, recombinant flagellin (rFLA) from Vibrio anguillarum and its D1 domain (rND1) are able to promote in vitro an upregulation of pro-inflammatory genes in gilthead seabream (Sparus aurata) and rainbow trout (Oncorhynchus mykiss) macrophages. This study evaluated the in vitro and in vivo stimulatory/adjuvant effect for rFLA and rND1 during P. salmonis vaccination in Atlantic salmon (Salmo salar). We demonstrated that rFLA and rND1 are molecules able to generate an acute upregulation of pro-inflammatory cytokines (IL-1β, IL-8, IL-12β), allowing the expression of genes associated with T-cell activation (IL-2, CD4, CD8β), and differentiation (IFNγ, IL-4/13, T-bet, Eomes, GATA3), in a differential manner, tissue/time dependent way. Altogether, our results suggest that rFLA and rND1 are valid candidates to be used as an immuno-stimulant or adjuvants with existing vaccines in farmed salmon.

鞭毛蛋白是鞭毛的主要成分，也是 Toll 样受体 5 的配体。据报道，来自鳗弧菌的重组鞭毛蛋白 (rFLA)及其 D1 结构域 (rND1) 能够在体外促进促炎基因的上调在金头鲷 ( Sparus aurata ) 和虹鳟鱼 ( Oncorhynchus mykiss ) 巨噬细胞中。本研究评估了大西洋鲑（Salmo salar）鲑鱼疫苗接种过程中rFLA和 rND1的体外和体内刺激/辅助作用。我们证明 rFLA 和 rND1 是能够产生促炎细胞因子（IL-1β、IL-8、IL-12β）急性上调的分子，允许与 T 细胞活化相关的基因（IL-2、CD4 、CD8β）和分化（IFNγ、IL-4/13、T-bet、Eomes、GATA3），以不同的方式，组织/时间依赖的方式。总之，我们的结果表明 rFLA 和 rND1 是有效的候选者，可用作养殖鲑鱼中现有疫苗的免疫刺激剂或佐剂。