title: Can immunostimulants efficiently replace antibiotic in striped catfish (Pangasianodon hypophthalmus) against bacterial infection by Edwardsiella ictaluri?
abstract: The present study was performed to determine the efficacy of lipopolysaccharide (LPS) and levamisole on immune response and disease resistance in striped catfish and to compare their respective efficiency with the one of an antibiotic treatment after infection of fish by the bacteria Edwardsiella ictaluri. Fish were divided into 3 groups and each group was injected with LPS (3 mg/kg fish), levamisole (5 mg/kg fish) or phosphate buffer saline as control. At day 21st post immunostimulant injection, fish were bled for assaying immunological variables and then challenged with E. ictaluri. Three days after bacterial infection, an antibiotic treatment was applied into fish subgroups and mortality was compared daily between antibiotic treated and untreated fish until 2 weeks post-challenge. LPS and levamisole significantly enhanced non-specific immune responses such as respiratory burst, lysozyme and complement activity in fish compared with control (p < 0.05). Respiratory burst and complement activity significantly increased in levamisole groups when compared with LPS groups while lysozyme activity did not differ significantly between immunostimulant treatments. Total immunoglobulins significantly increased in levamisole treatment compared with control. After challenge test, accumulated mortality was reduced significantly in both non-antibiotic and antibiotic subgroups of LPS and levamisole compared with control. Moreover, no differences of mortality were observed between fish treated with levamisole or LPS without antibiotics and control fish treated with antibiotics. These results support the possible replacement of antibiotics in striped catfish farming by immunostimulants such as levamisole and LPS.
authors.affiliation: Research Unit in Environmental and Evolutionary Biology, University of Namur (FUNDP), Rue de Bruxelles 61, B-5000 Namur, Belgium; College of Aquaculture and Fisheries, Cantho University, Campus II, Cantho City, Viet Nam. Electronic address: btbhang@ctu.edu.vn.
authors.forename: Bui Thi
authors.initials: BT
authors.lastname: Bich Hang
authors.affiliation: College of Aquaculture and Fisheries, Cantho University, Campus II, Cantho City, Viet Nam. Electronic address: ntphuong@ctu.edu.vn.
authors.forename: Nguyen Thanh
authors.initials: NT
authors.lastname: Phuong
authors.affiliation: Research Unit in Environmental and Evolutionary Biology, University of Namur (FUNDP), Rue de Bruxelles 61, B-5000 Namur, Belgium. Electronic address: patrick.kestemont@unamur.be.
authors.forename: Patrick
authors.initials: P
authors.lastname: Kestemont
mesh_terms: D000276:Adjuvants, Immunologic / Q000494:pharmacology*; D000818:Animals; D000900:Anti-Bacterial Agents / Q000494:pharmacology; D002397:Catfishes; D060467:Disease Resistance / Q000187:drug effects; D020610:Edwardsiella ictaluri / Q000502:physiology; D004756:Enterobacteriaceae Infections / Q000276:immunology / Q000382:microbiology / Q000662:veterinary*; D005393:Fish Diseases / Q000276:immunology* / Q000382:microbiology; D007978:Levamisole / Q000494:pharmacology*; D008070:Lipopolysaccharides / Q000494:pharmacology*
chemical_list: D000276:Adjuvants, Immunologic; D000900:Anti-Bacterial Agents; D008070:Lipopolysaccharides; D007978:Levamisole
keywords: Immune system; Levamisole; Lipopolysaccharide; Striped catfish