DAO 63:267-271 (2005)  -  doi:10.3354/dao063267

Epitopes associated with mature spores not recognized on Kudoa thyrsites from recently infected Atlantic salmon smolts

Catherine A. Young1, Simon R. M. Jones2,*

1Department of Biology, University of Victoria, Victoria, British Columbia V8W 3N5, Canada
2Pacific Biological Station, Department of Fisheries and Oceans, 3190 Hammond Bay Road, Nanaimo, British Columbia V9R 5K6, Canada
*Corresponding author. Email:

ABSTRACT: Atlantic salmon Salmo salar skeletal muscle was examined for Kudoa thyrsites by polymerase chain reaction (PCR) and positive fish were further examined by in situ hybridization (ISH) and immunohistochemistry (IHC). The infection was detected in 42% of salmon by PCR following a 60 d exposure to infective seawater at a temperature of 10°C (= 600 degree-days, °D). The parasite was detected by ISH in skeletal and cardiac muscle but not in gill, kidney, spleen, liver, stomach, intestine, pyloric caeca and skin. None of 4 monoclonal antibodies (2F4, 4H2, 1H2, 3E8) raised against mature K. thyrsites spores reacted with the stages identified by ISH following a 600 °D exposure, but they did react with ISH-identified stages following a 1600 °D exposure. In contrast, a polyclonal antibody reacted with K. thyrsites stages in salmon with both 600 and 1600 °D exposures, suggesting that the parasite observed in 600 °D infections represents an antigenically distinct developmental stage of K. thyrsites.


KEY WORDS: Kudoa thyrsites · Myxosporea · Salmo salar · In situ hybridization · Immunohistochemistry


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