Guevara Soto Maricruz, Vidondo Beatriz, Vaughan Lloyd, Seth-Smith Helena M B, Nufer Lisbeth, Segner Helmut, Rubin Jean-Francois, Schmidt-Posthaus Heike
Centre of Fish and Wildlife Health, Department of Infectious Diseases and Pathobiology, University of Bern, Bern, Switzerland.
Institute of Veterinary Public Health, University of Bern, Bern, Switzerland.
Arch Microbiol. 2016 May;198(4):315-24. doi: 10.1007/s00203-016-1192-x. Epub 2016 Jan 22.
We present the first study comparing epitheliocystis in a wild and farmed salmonid in Europe. Sampling three tributaries to the Lake Geneva, including one from headwaters to river mouth, revealed an unequal distribution of epitheliocystis in brown trout (Salmo trutta). When evaluated histologically and comparing sites grouped as wild versus farm, the probability of finding infected trout is higher on farms. In contrast, the infection intensities, as estimated by the number of cysts per gill arch, were higher on average and showed maximum values in the wild trout. Sequence analysis showed the most common epitheliocystis agents were Candidatus Piscichlamydia salmonis, all clustering into a single clade, whereas Candidatus Clavichlamydia salmonicola sequences cluster in two closely related subspecies, of which one was mostly found in farmed fish and the other exclusively in wild brown trout, indicating that farms are unlikely to be the source of infections in wild trout. A detailed morphological analysis of cysts using transmission electron microscopy revealed unique features illustrating the wide divergence existing between Ca. P. salmonis and Ca. C. salmonicola within the phylum Chlamydiae.
我们展示了第一项比较欧洲野生和养殖鲑科鱼类上皮囊肿病的研究。对日内瓦湖的三条支流进行采样，包括一条从源头到河口的支流，结果显示褐鳟（Salmo trutta）上皮囊肿病的分布不均。在进行组织学评估并比较分为野生组和养殖组的采样点时，发现养殖场所感染鳟鱼的概率更高。相比之下，以每鳃弓囊肿数量估计的感染强度平均更高，且在野生鳟鱼中出现最大值。序列分析表明，最常见的上皮囊肿病病原体是鲑鱼衣原体（Candidatus Piscichlamydia salmonis），所有序列都聚为一个单枝，而鲑鱼棒状衣原体（Candidatus Clavichlamydia salmonicola）序列聚为两个密切相关的亚种，其中一个主要在养殖鱼类中发现，另一个仅在野生褐鳟中发现，这表明养殖场不太可能是野生鳟鱼感染的源头。使用透射电子显微镜对囊肿进行详细的形态学分析，揭示了独特的特征，说明了衣原体门内鲑鱼衣原体和鲑鱼棒状衣原体之间存在的广泛差异。
