title: Goldfish (Carassius auratus L.) possess natural antibodies with trypanocidal activity towards Trypanosoma carassii in vitro.
abstract: Natural infection of cyprinids, such as carp, with the extracellular protozoan parasite Trypanosoma carassii can attain up to 100% prevalence and cause significant host morbidity and mortality, particularly in aquaculture settings. Host recovery from T. carassii infection has been shown to be antibody (Immunoglobulin M; IgM)-mediated, conferring long-term immunity in recovered animals upon challenge. To assess the role of IgM in parasite clearance in the goldfish, IgM was purified by PEG-6000 precipitation from goldfish serum collected at 0 (naïve), 21 (peak parasitaemia) and 42 (recovery phase; immune) days post infection (dpi) and used for in vitro assays. Purified IgM from 0, 21, and 42 dpi serum showed dose- and time-dependent trypanocidal activity in vitro. Incubation of T. carassii with 0 dpi IgM showed the greatest reduction in trypanosome numbers after 24 h, followed by 42 dpi IgM, and finally by 21 dpi IgM. The trypanocidal activity of the PEG-purified IgM was abrogated by pre-absorption with parasites in vitro and was affected by temperature. Furthermore, studies using 0 dpi IgM purified using gel permeation chromatography showed increased trypanocidal activity, with complete elimination of parasites after 12 h when incubated with 200 μg of 0 dpi IgM, or by 24 h when incubated with 80 μg or 100 μg of 0 dpi IgM. Lastly, in vivo passive transfer experiments demonstrated that while immune serum or purified IgM from 42 dpi serum conferred protection against a challenge, neither 0 dpi serum or 0 dpi purified IgM conferred protection against challenge with T. carassii.
authors: Department of Biological Sciences, University of Alberta, Edmonton, Alberta, Canada.
authors: Barbara A
authors: BA
authors: Katzenback
authors: Debbie A
authors: DA
authors: Plouffe
authors: Miodrag
authors: M
authors: Belosevic
mesh_terms: D000818:Animals; D000913:Antibodies, Protozoan / Q000097:blood; D017756:Aquaculture; D015153:Blotting, Western / Q000662:veterinary; D004591:Electrophoresis, Polyacrylamide Gel / Q000662:veterinary; D005393:Fish Diseases / Q000276:immunology* / Q000469:parasitology; D006054:Goldfish; D007106:Immune Sera / Q000276:immunology; D007075:Immunoglobulin M / Q000097:blood; D059208:Parasite Load / Q000662:veterinary; D018512:Parasitemia / Q000662:veterinary*; D014344:Trypanocidal Agents / Q000097:blood; D014345:Trypanosoma / Q000276:immunology*; D014352:Trypanosomiasis / Q000276:immunology / Q000469:parasitology / Q000662:veterinary*
chemical_list: D000913:Antibodies, Protozoan; D007106:Immune Sera; D007075:Immunoglobulin M; D014344:Trypanocidal Agents