title: Coordinated down-regulation of the antigen processing machinery in the gills of amoebic gill disease-affected Atlantic salmon (Salmo salar L.).
abstract: Several important cultured marine fish are highly susceptible to an ectoparasitic condition known as amoebic gill disease (AGD). In AGD-affected fish, modulation of IL-1beta, p53 and p53-regulated transcripts is restricted to the (multi)focal AGD-associated gill lesions. To determine whether this lesion-restricted modulation of transcripts occurs on a transcriptome-wide scale and to identify mechanisms that underpin the susceptibility of fish to AGD, we compared the transcriptome of AGD lesions with "normal" tissue from AGD-affected and healthy individuals. Global gene expression profiling using a 16K salmonid microarray, revealed a total of 176 significantly regulated annotated features and of those, the modulation of 99 (56%) was lesion-restricted. Annotated transcripts were classified according to functional gene ontology. Within the immune response category, transcripts were almost universally down-regulated. In AGD-affected tissue, significant, coordinated down-regulation of the major histocompatibility complex class I (MHC I) pathway-related genes occurred during the later stages of infection and appeared to be mediated by down-regulation of interferon-regulatory factor (IRF)-1, independent of interferon-alpha, interferon-gamma and IRF-2 expression. Within this micro-environment, suppression of the MHC I and possibly the MHC II pathways may inhibit the development of acquired immunity and could explain the unusually high susceptibility of Atlantic salmon to AGD.
authors.affiliation: Aquafin CRC, School of Aquaculture, Tasmanian Aquaculture and Fisheries Institute, University of Tasmania, Tasmania 7250, Australia. youngnd@postoffice.utas.edu.au
authors.forename: N D
authors.initials: ND
authors.lastname: Young
authors.forename: G A
authors.initials: GA
authors.lastname: Cooper
authors.forename: B F
authors.initials: BF
authors.lastname: Nowak
authors.forename: B F
authors.initials: BF
authors.lastname: Koop
authors.forename: R N
authors.initials: RN
authors.lastname: Morrison
mesh_terms: D000562:Amebiasis / Q000235:genetics / Q000276:immunology / Q000469:parasitology / Q000662:veterinary*; D016841:Amoebida; D000818:Animals; D017951:Antigen Presentation / Q000235:genetics*; D015536:Down-Regulation; D005393:Fish Diseases / Q000235:genetics / Q000276:immunology* / Q000469:parasitology; D029941:Fish Proteins / Q000235:genetics / Q000276:immunology / Q000378:metabolism; D020869:Gene Expression Profiling; D005805:Genes, MHC Class I; D005802:Genes, MHC Class II; D005880:Gills / Q000276:immunology* / Q000378:metabolism / Q000469:parasitology; D050856:Interferon Regulatory Factor-1 / Q000378:metabolism; D053583:Interleukin-1beta / Q000276:immunology / Q000378:metabolism; D020317:Salmo salar / Q000235:genetics / Q000276:immunology / Q000469:parasitology; D016159:Tumor Suppressor Protein p53 / Q000378:metabolism
chemical_list: D029941:Fish Proteins; D050856:Interferon Regulatory Factor-1; D053583:Interleukin-1beta; D016159:Tumor Suppressor Protein p53