Data_Sheet_3_Vaccine-Induced Protection Against Furunculosis Involves Pre-emptive Priming of Humoral Immunity in Arctic Charr.xlsx

With respect to salmonid aquaculture, one of the most important bacterial pathogens due to high mortality and antibiotic usage is the causative agent of typical furunculosis, Aeromonas salmonicida spp. salmonicida (Asal). In Atlantic salmon, Salmo salar, the host response during infections with Asal is well-documented, with furunculosis outbreaks resulting in significant mortality in commercial settings. However, less is known about the host-pathogen interactions in the emerging aquaculture species, Arctic charr Salvelinus alpinus. Furthermore, there is no data on the efficacy or response of this species after vaccination with commonly administered vaccines against furunculosis. To this end, we examined the immunological response of S. alpinus during infection with Asal, with or without administration of vaccines (Forte Micro®, Forte Micro® + Renogen®, Elanco Animal Health). Artic charr (vaccinated or unvaccinated) were i.p.-injected with a virulent strain of Asal (106 CFUs/mL) and tissues were collected pre-infection/post-vaccination, 8, and 29 days post-infection. Unvaccinated Arctic charr were susceptible to Asal with 72% mortalities observed after 31 days. However, there was 72–82% protection in fish vaccinated with either the single or dual-vaccine, respectively. Protection in vaccinated fish was concordant with significantly higher serum IgM concentrations, and following RNA sequencing and transcriptome assembly, differential expression analysis revealed several patterns and pathways associated with the improved survival of vaccinated fish. Most striking was the dramatically higher basal expression of complement/coagulation factors, acute phase-proteins, and iron hemostasis proteins in pre-challenged, vaccinated fish. Remarkably, following Asal infection, this response was abrogated and instead the transcriptome was characterized by a lack of immune-stimulation compared to that of unvaccinated fish. Furthermore, where pathways of actin assembly and FcγR-mediated phagocytosis were significantly differentially regulated in unvaccinated fish, vaccinated fish showed either the opposite regulation (ForteMicro®), or no impact at all (ForteMicro®Renogen®). The present data indicates that vaccine-induced protection against Asal relies on the pre-activation and immediate control of humoral immune parameters that is coincident with reduced activation of apoptotic (e.g., NF-κB) and actin-associated pathways.

针对鲑科水产养殖而言，因高致死率与抗生素使用量居高而成为最重要的细菌性致病菌之一的，是典型疖疮病的病原菌——杀鲑气单胞菌杀鲑亚种（Aeromonas salmonicida spp. salmonicida，简称Asal）。在大西洋鲑（Salmo salar）中，宿主感染Asal后的免疫应答已得到充分研究，疖疮病暴发会在商业养殖场景中造成显著死亡。但针对新兴养殖物种北极红点鲑（Salvelinus alpinus）的宿主-病原体互作研究仍相对匮乏，且尚无该物种接种常用疖疮病疫苗后的免疫应答与疫苗效力相关数据。
为此，本研究探究了北极红点鲑在感染Asal时的免疫应答，同时设置了不同疫苗接种组别：单剂Forte Micro®、双剂Forte Micro® + Renogen®（均由礼蓝动保（Elanco Animal Health）推出）。将接种或未接种疫苗的北极红点鲑以强毒株Asal（10⁶ CFU/mL）进行腹腔注射接种，并分别于疫苗接种后（感染前）、感染后第8天及第29天采集组织样本。
未接种疫苗的北极红点鲑对Asal易感，感染31天后死亡率达72%；而接种单剂或双剂疫苗的鱼群分别可获得72%~82%的保护率。该保护效果与接种组鱼群的血清免疫球蛋白M（IgM）浓度显著升高相一致。通过RNA测序（RNA sequencing）与转录组组装（transcriptome assembly）开展的差异表达分析，揭示了与接种组鱼群存活率提升相关的多种表达模式及信号通路。
最显著的特征是，攻毒前已接种疫苗的鱼群体内，补体/凝血因子（complement/coagulation factors）、急性期蛋白（acute phase-proteins）及铁稳态蛋白（iron hemostasis proteins）的基础表达水平显著升高。值得注意的是，在Asal感染后，这种预先升高的免疫应答被消除，与未接种组鱼群相比，接种组鱼群的转录组反而呈现免疫刺激不足的特征。此外，未接种组鱼群中肌动蛋白组装及FcγR介导的吞噬作用（FcγR-mediated phagocytosis）通路显著差异调控，而接种单剂疫苗组（ForteMicro®）呈现相反的调控模式，接种双剂疫苗组（ForteMicro®+Renogen®）则无明显影响。
本研究数据表明，疫苗诱导的抗Asal保护作用依赖于体液免疫参数的预激活与即时调控，这与细胞凋亡通路（如核因子κB（NF-κB））及肌动蛋白相关通路的激活减弱相契合。