The emergence of epitheliocystis in the upper Rhone region: evidence for Chlamydiae in wild and farm salmonid populations
Helmut Segner, Heike Schmidt-Posthaus, Maricruz Guevara Soto, Lisbeth Nufer, Beatriz Vidondo Curras, Lloyd Vaughan, Helena Seth-Smith, Jean-Francois Rubin
2016
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
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... , 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 sub-species, 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. Abstract Important notes This study compares epitheliocystis in wild and farmed brown trout in three tributaries to the Lake Geneva. It shows an unequal distribution of epitheliocystis in brown trout. When evaluated histologically and comparing sites grouped as wild versus farm, the probability of finding infected trout is higher on farms, whereas infection intensities were higher in 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 sub-species, 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. source: https://doi.org/10.7892/boris.78412 | downloaded: 25.2.2020
doi:10.7892/boris.78412
fatcat:cupnrvmh5rhuphv3opj4ft3jca