Differential rejection of salmon lice by pink and chum salmon: disease consequences and expression of proinflammatory genes.
The consequences of high (735 copepodids fish-1) and low (243 copepodids fish-1) level exposures of size-matched juvenile pink and chum salmon to Lepeophtheirus salmonis copepodids were examined. At both levels of exposure the prevalence and abundance of L. salmonis was significantly higher on chum salmon. In addition, the weight of exposed chum salmon following the high exposure was significantly less than that of unexposed chum salmon. At both exposures, the haematocrit of exposed chum salmon was significantly less than that of unexposed chum. Neither weight nor haematocrit of pink salmon was affected by exposures at these levels. Despite the presence of microscopic inflammatory lesions associated with attachment of L. salmonis on the epithelium of gill and fin of both salmon species, there were no mortalities following either exposure. A transient cortisol response was observed in chum salmon 21 d after low exposure. An earlier and quantitatively higher expression of the proinflammatory genes interleukin-8 (IL-8), tumour necrosis factor alpha-1 (TNFalpha-1) and interleukin-1beta (IL-1beta) in fin and head kidney of pink salmon suggested a mechanism of more rapid louse rejection in this species. Together, these observations indicate a relatively enhanced innate resistance to L. salmonis in the juvenile pink salmon compared with the juvenile chum salmon.
Jones
Simon R M
SR
Pacific Biological Station, 3190 Hammond Bay Road, Fisheries and Oceans Canada, Nanaimo, British Columbia V9T 6N7, Canada. joness@pac.dfo-mpo.gc.ca
Fast
Mark D
MD
Johnson
Stewart C
SC
Groman
David B
DB
D000199:Actins / Q000032:analysis / Q000096:biosynthesis / Q000235:genetics; D000818:Animals; D033342:Copepoda / Q000276:immunology*; D016207:Cytokines / Q000096:biosynthesis / Q000235:genetics / Q000276:immunology; D017931:DNA Primers / Q000737:chemistry; D004478:Ectoparasitic Infestations / Q000276:immunology / Q000473:pathology / Q000662:veterinary*; D005393:Fish Diseases / Q000276:immunology* / Q000469:parasitology / Q000473:pathology; D005398:Fisheries; D015870:Gene Expression / Q000276:immunology; D005880:Gills / Q000469:parasitology / Q000473:pathology; D006400:Hematocrit / Q000662:veterinary; D006790:Host-Parasite Interactions / Q000276:immunology; D006854:Hydrocortisone / Q000097:blood; D017685:Oncorhynchus keta / Q000276:immunology / Q000469:parasitology*; D020648:Peptide Elongation Factor 1 / Q000096:biosynthesis / Q000235:genetics / Q000276:immunology; D012474:Salmon / Q000276:immunology / Q000469:parasitology*; D013997:Time Factors
D000199:Actins; D016207:Cytokines; D017931:DNA Primers; D020648:Peptide Elongation Factor 1; D006854:Hydrocortisone