DAO 43:49-53 (2000)  -  doi:10.3354/dao043049

Innate susceptibility differences in chinook salmon Oncorhynchus tshawytscha to Loma salmonae (Microsporidia)

R. W. Shaw1,*, M. L. Kent2, M. L. Adamson3

1#9 26520 Twp Rd 512, Spruce Grove, Alberta T7Y 1G1, Canada
2Center for Salmon Disease Research, 220 Nash Hall, Oregon State University, Corvallis, Oregon 937331-3804, USA
3Department of Zoology, 6270 University Boulevard, University of British Columbia, Vancouver, British Columbia V6T 1Z4, Canada

ABSTRACT: Loma salmonae (Putz, Hoffman and Dunbar, 1965) Morrison & Sprague, 1981 (Microsporidia) is an important gill pathogen of Pacific salmon Oncorhynchus spp. in the Pacific Northwest. Three strains of chinook salmon O. tshawytscha were infected in 2 trials with L. salmonae by feeding of macerated infected gill tissue or per os as a gill tissue slurry. Intensity of infection was significantly higher in the Northern stream (NS) strain as compared to the Southern coastal (SC) and a hybrid (H) strain derived from these 2 strains. Both wet mount and histological enumeration of intensity of infection demonstrated strain differences. Survival in the NS strain was significantly lower than the other strains. The NS strain may represent a naive strain and be less able to mount an effective immune response against the parasite.


KEY WORDS: Loma salmonae · Microsporidia · Innate susceptibility


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