title: The emergence of epitheliocystis in the upper Rhone region: evidence for Chlamydiae in wild and farmed salmonid populations.
abstract: 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.
authors.affiliation: Centre of Fish and Wildlife Health, Department of Infectious Diseases and Pathobiology, University of Bern, Bern, Switzerland.
authors.forename: Maricruz
authors.initials: M
authors.lastname: Guevara Soto
authors.affiliation: Institute of Veterinary Public Health, University of Bern, Bern, Switzerland.
authors.forename: Beatriz
authors.initials: B
authors.lastname: Vidondo
authors.affiliation: Institute of Veterinary Pathology, University of Zurich, Zurich, Switzerland.
authors.forename: Lloyd
authors.initials: L
authors.lastname: Vaughan
authors.affiliation: Functional Genomics Center Zurich, University of Zurich, Zurich, Switzerland.
authors.forename: Helena M B
authors.initials: HM
authors.lastname: Seth-Smith
authors.affiliation: Institute of Veterinary Pathology, University of Zurich, Zurich, Switzerland.
authors.forename: Lisbeth
authors.initials: L
authors.lastname: Nufer
authors.affiliation: Centre of Fish and Wildlife Health, Department of Infectious Diseases and Pathobiology, University of Bern, Bern, Switzerland.
authors.forename: Helmut
authors.initials: H
authors.lastname: Segner
authors.affiliation: Fondation de la Maison de la Rivière, Tolochenaz, Switzerland.
authors.forename: Jean-Francois
authors.initials: JF
authors.lastname: Rubin
authors.affiliation: Centre of Fish and Wildlife Health, Department of Infectious Diseases and Pathobiology, University of Bern, Bern, Switzerland. heike.schmidt@vetsuisse.unibe.ch.
authors.forename: Heike
authors.initials: H
authors.lastname: Schmidt-Posthaus
mesh_terms: D000818:Animals; D017756:Aquaculture; D002695:Chlamydiales / Q000145:classification* / Q000235:genetics / Q000502:physiology* / Q000648:ultrastructure; D060085:Coinfection; D005060:Europe; D005393:Fish Diseases / Q000382:microbiology* / Q000473:pathology; D005880:Gills / Q000382:microbiology / Q000473:pathology / Q000648:ultrastructure; D016905:Gram-Negative Bacterial Infections / Q000382:microbiology / Q000473:pathology / Q000662:veterinary*; D046529:Microscopy, Electron, Transmission; D008969:Molecular Sequence Data; D010802:Phylogeny; D012336:RNA, Ribosomal, 16S / Q000235:genetics; D045483:Rivers; D012689:Sequence Homology, Nucleic Acid; D013557:Switzerland; D014337:Trout
chemical_list: D012336:RNA, Ribosomal, 16S
keywords: Brown trout; Candidatus Clavichlamydia salmonicola; Candidatus Piscichlamydia salmonis; Farm; River