Livestock and Aquaculture, Commonwealth Scientific and Industrial Research Organisation, Agriculture and Food, Hobart, Tasmania, Australia.
Institute for Marine and Antarctic Studies, University of Tasmania, Launceston, Tasmania, Australia.
J Fish Dis. 2022 Nov;45(11):1721-1731. doi: 10.1111/jfd.13694. Epub 2022 Aug 25.
Epitheliocystis, an intracellular bacterial infection in the gills and skin epithelium, has been frequently reported in Atlantic salmon (Salmo salar) during freshwater production in a number of countries. This study describes the prevalence and intensity of a natural epitheliocystis infection present in the gills of two strains of Atlantic salmon reared in either a flow-through (FT) or a recirculation aquaculture system (RAS) in Ireland. Repeated sampling of gills prior to and throughout seawater transfer, histology and quantitative real-time PCR were used to determine infection prevalence and intensity. Despite no clinical gill disease, and minor histopathological changes, epitheliocystis lesions were identified in histology at all time points. Specific PCR confirmed the presence of Candidatus Clavichlamydia salmonicola in both strains and its number of copies was correlated with intensity of epitheliocystis lesions. A significant interaction between hatchery system and fish strain on the prevalence and intensity of gill epitheliocystis was found both using histological and molecular methods. Specifically, fish from FT had higher prevalence and intensity than RAS reared fish and within FT, the Irish cohort were more affected than Icelandic.
类晶体囊病是一种发生在鱼类皮肤和鳃上皮细胞内的细菌性传染病，在多个国家的鲑鱼淡水养殖阶段经常发生。本研究描述了在爱尔兰采用流水（FT）或循环水养殖系统（RAS）养殖的两个大西洋鲑品种的鳃中存在的天然类晶体囊病的流行率和严重程度。在海水转移之前和整个过程中，通过重复取样鳃、组织学和实时定量 PCR 来确定感染的流行率和严重程度。尽管没有临床鳃病和轻微的组织病理学变化，但在所有时间点的组织学检查中都发现了类晶体囊病病变。特异性 PCR 证实了两品种中均存在 Candidatus Clavichlamydia salmonicola，其拷贝数与类晶体囊病病变的严重程度相关。使用组织学和分子方法均发现孵化系统和鱼类品种对鳃上皮类晶体囊病的流行率和严重程度存在显著的相互作用。具体而言，来自 FT 的鱼类比 RAS 养殖的鱼类具有更高的流行率和严重程度，而在 FT 中，爱尔兰群体比冰岛群体受到的影响更大。
