title: Characterization of 'Candidatus Syngnamydia salmonis' (Chlamydiales, Simkaniaceae), a bacterium associated with epitheliocystis in Atlantic salmon (Salmo salar L.).
abstract: Two Chlamydiales have previously been found to infect Atlantic salmon (Salmo salar L.), Candidatus Piscichlamydia salmonis and Candidatus Clavichlamydia salmonicola. Both develop intracellularly in cyst-like inclusions in gill cells, generally referred to as epitheliocysts. Here, we present evidence for the association of a novel species of Chlamydiales with epitheliocystis in Atlantic salmon. Based on its partial 16S rRNA gene sequence, it is a new member of the family Simkaniaceae, and a 95.7 % identity to the type species Candidatus Syngnamydia venezia suggests inclusion in the candidate genus Syngnamydia. The presence of the bacterium in epitheliocysts in gills of Atlantic salmon was demonstrated by RNA-RNA hybridization. Ultrastructurally, the novel bacterium produces pleomorphic reticulate bodies and elementary bodies (EBs) with a characteristic morphology. The EBs are short rods with a terminal disc-like cap area, a sub-apical spherical vacuole-like electron-lucent structure and a post-equatorial nucleoid. We propose the name Candidatus Syngnamydia salmonis for this new agent from epitheliocysts in seawater-reared salmon .
authors.affiliation: Department of Biology, University of Bergen, P.O. Box 7803, 5020, Bergen, Norway.
authors.forename: Stian
authors.initials: S
authors.lastname: Nylund
authors.forename: Andreas
authors.initials: A
authors.lastname: Steigen
authors.forename: Egil
authors.initials: E
authors.lastname: Karlsbakk
authors.forename: Heidrun
authors.initials: H
authors.lastname: Plarre
authors.forename: Linda
authors.initials: L
authors.lastname: Andersen
authors.forename: Marius
authors.initials: M
authors.lastname: Karlsen
authors.forename: Kuninori
authors.initials: K
authors.lastname: Watanabe
authors.forename: Are
authors.initials: A
authors.lastname: Nylund
mesh_terms: D000818:Animals; D002695:Chlamydiales / Q000145:classification* / Q000235:genetics / Q000302:isolation & purification* / Q000648:ultrastructure; D004847:Epithelial Cells / Q000382:microbiology / Q000648:ultrastructure; D005393:Fish Diseases / Q000382:microbiology* / Q000473:pathology; D005880:Gills / Q000382:microbiology* / Q000648:ultrastructure; D016905:Gram-Negative Bacterial Infections / Q000382:microbiology / Q000473:pathology / Q000662:veterinary*; D002479:Inclusion Bodies / Q000382:microbiology* / Q000648:ultrastructure; D008969:Molecular Sequence Data; D012336:RNA, Ribosomal, 16S / Q000235:genetics; D020317:Salmo salar / Q000382:microbiology*; D012623:Seawater; D017422:Sequence Analysis, DNA; D014617:Vacuoles / Q000648:ultrastructure
chemical_list: D012336:RNA, Ribosomal, 16S