Protective immunity in fish against protozoan diseases.
The demand for and costs of producing land-based animal protein continues to escalate as the world population increases. Fish is an excellent protein, but the catch-fishery is stagnant or in decline. Intensive cage culture of fish is a viable option especially in countries with lakes/rivers and/or a long coastline; however, disease outbreaks will likely occur more frequently with cage culture. Hence protective strategies are needed, and one approach is to exploit the piscine immune system. This discussion highlights immunity (innate/natural and adaptive/acquired) in fish against three pathogenic protozoa (Amyloodinium ocellatum, Ichthyophthirius multifiliis and Cryptobia salmositica). Histone-like proteins in the mucus and skin of naturally resistant fish kill trophonts of A. ocellatum, and also may cause abnormal development of tomonts. Breeding of Cryptobia-resistant brook charrs is possible as resistance is controlled by a dominant Mendelian locus, and the parasite is lysed via the Alternative Pathway of Complement Activation. Production of transgenic Cryptobia-tolerant salmon is an option. Recovered fish are protected from the three diseases (acquired immunity). Live I. multifiliis theronts injected intraperitoneally into fish elicit protection. Also, a recombinant immoblizing-antigen vaccine against ichthyophthirosis has been developed but further evaluations are necessary. The live Cryptobia vaccine protects salmonids from infections while the DNA-vaccine stimulates production of antibodies to neutralize the disease causing factor (metalloprotease) in cryptobiosis; hence infected fish recover more rapidly.
Woo
P T K
PT
Department of Integrative Biology, University of Guelph, Guelph, Ontario N1G 2W1, Canada. pwoo@uoguelph.ca
D000818:Animals; D000913:Antibodies, Protozoan / Q000097:blood; D017756:Aquaculture / Q000379:methods; D001947:Breeding; D016770:Ciliophora Infections / Q000276:immunology / Q000517:prevention & control / Q000662:veterinary; D005393:Fish Diseases / Q000276:immunology* / Q000517:prevention & control; D005398:Fisheries / Q000379:methods; D005399:Fishes / Q000276:immunology* / Q000469:parasitology; D016803:Hymenostomatida / Q000254:growth & development / Q000276:immunology; D007113:Immunity, Innate / Q000235:genetics / Q000276:immunology; D016830:Kinetoplastida / Q000254:growth & development / Q000276:immunology; D009093:Mucus / Q000276:immunology; D011529:Protozoan Infections, Animal / Q000276:immunology* / Q000517:prevention & control; D016052:Protozoan Vaccines / Q000008:administration & dosage / Q000276:immunology; D012487:Salmonidae / Q000276:immunology / Q000469:parasitology; D012867:Skin / Q000737:chemistry / Q000276:immunology; D014611:Vaccination / Q000379:methods / Q000662:veterinary
D000913:Antibodies, Protozoan; D016052:Protozoan Vaccines