The use of polyclonal antibodies for detection of Myxidium leei infections in fish

Myxidium leei (Myxozoa: Myxosporea) is a histozoic parasite which causes severe chronic gut infections in cultured marine fish. A polyclonal antiserum raised in ICR mice against Myxidium leei cells recovered from infected gilthead seabream Sparus aurata L. was used for the detection of the parasite cells in the intestinal mucosa of M. leei infected S. aurata and red drum, Sciaenops ocellatus. Air-dried smears taken from Myxidium-infected gut of S. aurata produced a strong flurescent background staining with this antibody, probably due to the presence of antibodies specific to S. aurata antiqens in this antiserum. In contrast, exclusive immunofluorescence staining of the parasite cells was obtained with the same antibody in infected red drum intestinal mucosa smears. The results indicate that detection and identification of M. leei in smears of fish gut mucosa may be possible by immunoflourescence using antibodies raised against Myxidium cells of xenogeneic species. The method may be a useful diagnostic tool for detecting early, asymptomatic infections in intensively-reared mariculture stocks.