Cefas Weymouth Laboratory, The Nothe, Barrack Road, Weymouth, Dorset DT4 8UB, UK.
Dis Aquat Organ. 2023 Aug 3;155:7-19. doi: 10.3354/dao03737.
Enteric redmouth disease (ERM) caused by the enterobacterium Yersinia ruckeri poses a significant threat to salmonid aquaculture globally. Despite decades of experimental infection studies, key knowledge gaps remain regarding the onset of disease susceptibility and mechanisms of immunity during early developmental stages, undermining disease management efforts in all susceptible life-stages. In this study, a series of immersion challenges were conducted, challenging and re-challenging rainbow trout Oncorhynchus mykiss (Walbaum) at 7, 14 and 51 d post-hatch (dph; mean weights = 0.085, 0.1 and 2.0 g respectively) to high concentrations (1.72 × 107-1.1 × 108 CFU) of Y. ruckeri at 15°C. This study indicates the hitherto unknown initial point of susceptibility to infection as the time of first ingestion of exogenous food (14 dph), and shows that individuals surviving primary challenge at 14 dph are significantly more likely to survive re-challenge at 51 dph compared with naive individuals (hazard ratio = 1.446, p = 0.032). Other key findings include large variation in mortality between different development-stages, from 21.1% at 14 dph to 81.2% at 51 dph, and novel age-dependent symptoms not reported previously. Results from this study enhance our understanding of ERM in juvenile rainbow trout and inform the development of improved aquatic animal health management strategies, thereby contributing to the productivity and sustainability of salmonid aquaculture into the future.
肠型红嘴病（ERM）由肠型鲁克氏耶尔森菌引起，对全球鲑鱼养殖业构成重大威胁。尽管经过几十年的实验感染研究，但在早期发育阶段疾病易感性的发生和免疫机制方面仍存在关键知识空白，这削弱了所有易感生命阶段的疾病管理工作。在这项研究中，对彩虹鳜 Oncorhynchus mykiss（Walbaum）进行了一系列浸泡挑战，在孵化后 7、14 和 51 天（平均体重分别为 0.085、0.1 和 2.0 克）时，用高浓度（1.72×107-1.1×108 CFU）的 Y. ruckeri 进行挑战和再挑战，温度为 15°C。本研究表明，易感性感染的最初未知时间点是首次摄入外源性食物的时间（14 天），并表明在 14 天龄时幸存于初次挑战的个体在 51 天龄时再次挑战的存活可能性显著高于初次挑战的个体（风险比=1.446，p=0.032）。其他关键发现包括不同发育阶段之间死亡率的巨大差异，从 14 天龄的 21.1%到 51 天龄的 81.2%，以及以前未报道过的新型年龄依赖性症状。本研究的结果提高了我们对幼鲑鱼肠型红嘴病的认识，并为改进水生动物健康管理策略提供了信息，从而为未来鲑鱼养殖业的生产力和可持续性做出贡献。
