Submitted to: American Association of Veterinary Parasitologists Proceedings
Publication Type: Abstract Only
Publication Acceptance Date: 5/23/2007
Publication Date: 7/14/2007
Citation: Xu, D., Klesius, P.H., Shoemaker, C.A. 2007. Protective immunity of channel catfish against parasite Ichthyophthirius. American Association of Veterinary Parasitologists Proceedings. 105: p.101.
Technical Abstract: The ciliated protozoan Ichthyophthirius multifiliis (Ich) causes high mortality and economic loss in fish aquaculture. Chemical treatment of Ich infection is usually ineffective, costly for fish farmers, and causes public concern regarding food and environmental safety. The aim of this study was to assess protective immunity in channel catfish against parasite Ich following immunization. Immunizations were done with live theronts or sonicated trophonts by both bath immersion and intraperitoneal (IP) injection. Levels of anti-Ich antibodies were measured after immunization by theront immobilization assay. The level of Ich infection and survival of catfish were determined after theront challenge at a dose of 15,000 theronts per fish. Anti-Ich antibody levels were significantly higher in fish immunized with live theronts or with sonicated trophonts administered by IP injection compared to fish immunized with sonicated trophonts by immersion, with bovine serum albumin, or non-immunized controls. Host protection was achieved in fish immunized with live theronts (immersion or IP injection) or with sonicated trophonts by IP injection. Anti-Ich antibodies immobilized theronts in vitro. Fewer fish were infected and the infection was less severe for fish exposed to theronts treated with anti-Ich antibodies than fish exposed to theronts treated with serum from control fish. The result of the study indicated that fish can be successfully immunized with live or sonicated trophont and anti-Ich antibody appeared to be responsible for protection against Ich.