title: Signatures of resistance to Lepeophtheirus salmonis include a TH2-type response at the louse-salmon interface.
abstract: Disease outbreaks with the salmon louse Lepeophtheirus salmonis cause significant economic losses in mariculture operations worldwide. Variable innate immune responses at the louse-attachment site contribute to differences in susceptibility among species such that members of Salmo spp. are more susceptible to infection than those of some Oncorhynchus spp. Relatively little is known about the mechanisms that contribute to disease resistance or susceptibility to L. salmonis in salmon. Here, we utilize histochemistry and transcriptomics in a comparative infection model with susceptible (Atlantic, sockeye) and resistant (coho) salmon. At least three cell populations (MHIIβ+, IL1β+, TNFα+) were activated in coho salmon skin during L. salmonis infection. Locally elevated expression of several pro-inflammatory mediators (e.g. IL1β, IL8, TNFα, COX2, C/EBPβ), and tissue repair enzymes (MMP9, MMP13) were detected in susceptible and resistant species. However, responses specific to coho salmon (e.g. IL4, IL6, TGFβ) or responses shared among susceptible salmon (e.g. SAP, TRF, Cath in Atlantic and sockeye salmon) provide evidence for species-specific pathways contributing to resistance or susceptibility, respectively. Our results confirm the importance of an early pro-inflammatory TH1-type pathway as an initial host response during infection with Pacific sea lice, and demonstrate subsequent regulatory TH2-type processes as candidate defense mechanisms in the skin of resistant coho salmon.
authors.affiliation: Centre for Biomedical Research, Department of Biology, University of Victoria, Victoria, British Columbia V8W 3N5, Canada.
authors.forename: Laura M
authors.initials: LM
authors.lastname: Braden
authors.affiliation: Centre for Biomedical Research, Department of Biology, University of Victoria, Victoria, British Columbia V8W 3N5, Canada.
authors.forename: Ben F
authors.initials: BF
authors.lastname: Koop
authors.affiliation: Pacific Biological Station, 3190 Hammond Bay Road, Nanaimo, British Columbia V9T 6N7, Canada. Electronic address: simon.jones@dfo-mpo.gc.ca.
authors.forename: Simon R M
authors.initials: SR
authors.lastname: Jones
mesh_terms: D000818:Animals; D033342:Copepoda / Q000276:immunology*; D060467:Disease Resistance / Q000276:immunology; D004198:Disease Susceptibility; D005260:Female; D005393:Fish Diseases / Q000276:immunology* / Q000469:parasitology; D005786:Gene Expression Regulation; D000949:Histocompatibility Antigens Class II / Q000276:immunology; D006790:Host-Parasite Interactions / Q000276:immunology*; D053583:Interleukin-1beta / Q000096:biosynthesis; D015847:Interleukin-4 / Q000096:biosynthesis; D015850:Interleukin-6 / Q000096:biosynthesis; D053509:Matrix Metalloproteinase 13 / Q000096:biosynthesis; D020317:Salmo salar / Q000276:immunology* / Q000469:parasitology; D012867:Skin / Q000276:immunology / Q000469:parasitology; D013045:Species Specificity; D035182:TATA Box Binding Protein-Like Proteins / Q000096:biosynthesis; D018417:Th1 Cells / Q000276:immunology; D018418:Th2 Cells / Q000276:immunology*; D016212:Transforming Growth Factor beta / Q000096:biosynthesis; D014945:Wound Healing / Q000276:immunology
chemical_list: D000949:Histocompatibility Antigens Class II; D053583:Interleukin-1beta; D015850:Interleukin-6; D035182:TATA Box Binding Protein-Like Proteins; D016212:Transforming Growth Factor beta; D015847:Interleukin-4; D053509:Matrix Metalloproteinase 13
keywords: Ectoparasite; Gene expression; Immunohistochemistry; Lepeophtheirus salmonis; Salmon; T(H)2-type response