title: Neoparamoeba perurans n. sp., an agent of amoebic gill disease of Atlantic salmon (Salmo salar).
abstract: Amoebic gill disease (AGD) is a potentially fatal disease of some marine fish. Two amphizoic amoebae Neoparamoeba pemaquidensis and Neoparamoeba branchiphila have been cultured from AGD-affected fish, yet it is not known if one or both are aetiological agents. Here, we PCR amplified the 18S rRNA gene of non-cultured, gill-derived (NCGD) amoebae from AGD-affected Atlantic salmon (Salmo salar) using N. pemaquidensis and N. branchiphila-specific oligonucleotides. Variability in PCR amplification led to comparisons of 18S rRNA and 28S rRNA gene sequences from NCGD and clonal cultured, gill-derived (CCGD) N. pemaquidensis and N. branchiphila. Phylogenetic analyses inferred from either 18S or 28S rRNA gene sequences unambiguously segregated a lineage consisting of NCGD amoebae from other members of the genus Neoparamoeba. Species-specific oligonucleotide probes that hybridise 18S rRNA were designed, validated and used to probe gill tissue from AGD-affected Atlantic salmon. The NCGD amoebae-specific probe bound AGD-associated amoebae while neither N. pemaquidensis nor N. branchiphila were associated with AGD-lesions. Together, these data indicate that NCGD amoebae are a new species, designated Neoparamoeba perurans n.sp. and this is the predominant aetiological agent of AGD of Atlantic salmon cultured in Tasmania, Australia.
authors.affiliation: School of Aquaculture, Aquafin CRC, University of Tasmania, Locked Bag 1370, Launceston, Tasmania, Australia. youngnd@utas.edu.au
authors.forename: N D
authors.initials: ND
authors.lastname: Young
authors.forename: P B B
authors.initials: PB
authors.lastname: Crosbie
authors.forename: M B
authors.initials: MB
authors.lastname: Adams
authors.forename: B F
authors.initials: BF
authors.lastname: Nowak
authors.forename: R N
authors.initials: RN
authors.lastname: Morrison
mesh_terms: D000562:Amebiasis / Q000662:veterinary*; D000656:Amoeba / Q000235:genetics*; D000818:Animals; D005393:Fish Diseases / Q000469:parasitology*; D005399:Fishes / Q000469:parasitology; D005880:Gills / Q000469:parasitology; D016133:Polymerase Chain Reaction / Q000379:methods; D012337:RNA, Ribosomal, 18S / Q000235:genetics; D012339:RNA, Ribosomal, 28S / Q000235:genetics; D020317:Salmo salar / Q000469:parasitology*; D013648:Tasmania
chemical_list: D012337:RNA, Ribosomal, 18S; D012339:RNA, Ribosomal, 28S