title: Characterisation of an emerging rickettsia-like organism in Tasmanian farmed Atlantic salmon Salmo salar.
abstract: A rickettsia-like organism (RLO) was observed in farmed Atlantic salmon Salmo salar located in south-east Tasmania, Australia. Several assays such as immunoperoxidase, immunoelectron microscopy, polymerase chain reaction and nucleic acid sequencing, as well as phylogenetic analysis of rDNA sequences, were performed on infected fish tissues. Immunohistochemistry results suggested the presence of related antigenic determinants between the Tasmanian RLO and the type strain LF-89 of Piscirickettsia salmonis. However, sequence alignment demonstrated that the Tasmanian RLO contains a 19 bp deletion at the 3'-end of the internal transcribed spacer region of the rDNA operon, indicating a genetic divergence from P. salmonis isolates, which are exotic to Australia.
authors.affiliation: AAHL Fish Diseases Laboratory, Australian Animal Health Laboratory, CSIRO Livestock Industries, Private Bag 24, Geelong, Victoria 3220, Australia. serge.corbeil@csiro.au
authors.forename: Serge
authors.initials: S
authors.lastname: Corbeil
authors.forename: Alex D
authors.initials: AD
authors.lastname: Hyatt
authors.forename: Mark St J
authors.initials: MS
authors.lastname: Crane
mesh_terms: D000818:Animals; D001483:Base Sequence; D016000:Cluster Analysis; D004275:DNA, Ribosomal / Q000235:genetics; D005393:Fish Diseases / Q000382:microbiology*; D007124:Immunoenzyme Techniques; D007150:Immunohistochemistry; D007668:Kidney / Q000382:microbiology / Q000648:ultrastructure; D008099:Liver / Q000382:microbiology / Q000648:ultrastructure; D016253:Microscopy, Immunoelectron; D008969:Molecular Sequence Data; D010802:Phylogeny; D044147:Piscirickettsiaceae / Q000235:genetics*; D044225:Piscirickettsiaceae Infections / Q000662:veterinary*; D020317:Salmo salar; D016415:Sequence Alignment; D017422:Sequence Analysis, DNA; D013648:Tasmania
chemical_list: D004275:DNA, Ribosomal