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

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.

Long‐term epidemiological survey of Kudoa thyrsites (Myxozoa) in Atlantic salmon (Salmo salar L.) from commercial aquaculture farms

“…Our evidence of first infections (355 and 509 degree days) was similar to the 6-week detection (approximately 420 degree days) found by Moran et al (1999a) by PCR in multiple tissue, including blood. Visually we were able to detect K. thyrsites in the muscle after 975 and 1113, but not at 778 degree days, similar to the 1000 degree days reported by Moran & Kent (1999), but not as early as Moran et al (1999a) and Young & Jones (2005) where early stages of cysts were described around 600-630 degree days.…”

“…Visually we were able to detect K. thyrsites in the muscle after 975 and 1113, but not at 778 degree days, similar to the 1000 degree days reported by Moran & Kent (), but not as early as Moran et al . () and Young & Jones () where early stages of cysts were described around 600–630 degree days.…”

Insights into myxozoan composition and physiology revealed by histochemical properties of myxospores

“…Similar to staining differences observed between stages of myxospore development, differential staining between mother and daughter cells suggests changes in composition throughout their development, although no differences in staining were appreciated between extrasporogonic stages located within the interstitial space and tubules. This is consistent with previous work which suggests myxozoan structural and antigenic configuration is not conserved across developmental stages (Young & Jones, 2005). Myxozoans are thought to express different antigenic profiles as a result of adaptation to different hosts and environments across their developmental timeline.…”

Acquired Protective Immunity in Atlantic Salmon Salmo salar against the Myxozoan Kudoa thyrsites Involves Induction of MHIIβ + CD83 + Antigen-Presenting Cells

“…Indeed, in Atlantic salmon infected with K. thyrsites, weakly infective circulating extrasporogonic stages have been detected (13,34), which may interact with antigen-presenting cells (APCs) to activate the host immune response. There is evidence of stage-specific surface antigens in K. thyrsites (76), raising the possibility of differential stimulation of defense responses during early and late stages of parasite development.…”