The effects of feeding immunostimulant β-glucan on the immune response of Pangasianodon hypophthalmus.
Immunostimulants are food additives used by the aquaculture industry to enhance the immune response of fish, and although β-glucans are now commonly used for this purpose in aquaculture, little is known about their effects on the immune response of Pangasianodon hypophthalmus. Thus, a variety of immune parameters (e.g. phagocytosis, respiratory burst, lysozyme, complement, peroxidase, total protein, total anti-protease, total IgM, natural antibody titres, and specific IgM titres) was examined in this species after feeding fish with a basal control diet or diets supplemented with 0.05, 0.1, or 0.2 g/kg fungal-derived β-glucan or 0.1% commercial yeast-derived β-glucan, as a positive control diet, for a period of four weeks. The effect of the glucans on disease resistance was then evaluated by experimentally infecting the fish with Edwardsiella ictaluri by immersion and mortalities monitored for 14 days. Samples were collected from fish for analysis at 0, 1, 3, 7, 14, 21 and 28 days post-feeding (dpf), and also at 14 days post infection (dpi). The lowest dose of fungal-derived β-glucan (0.05%) appeared insufficient to effectively stimulate the immune response of the fish, while those fed with the two highest levels of fungal-derived β-glucan had enhanced immune responses compared to the control group. Significantly elevated levels of respiratory burst activity on all days examined (P < 0.05) and lysozyme activity on 7 dpf were found in the group fed 0.2% fungal-derived β-glucan, while plasma anti-protease activity was significantly enhanced (P < 0.05) by 21 dpf, natural antibody titres by 3 dpf and complement activity by 7 dpf and also at 14 dpi in the group fed 0.1% fungal-derived β-glucan. No statistical differences was seen in the level of mortalities between the dietary groups, although the group fed with the control diet had the highest level of mortalities and the groups fed with commercial yeast-derived β-glucan and 0.2% fungal-derived β-glucan the lowest.
Institute of Aquaculture, School of Natural Sciences, University of Stirling, Stirling, Scotland, UK; Faculty of Veterinary Science, Mahidol University, Salaya Campus, Nakornpathom, 73170, Thailand. Electronic address: wanna.sir@mahidol.ac.th.
Wanna
W
Sirimanapong
Institute of Aquaculture, School of Natural Sciences, University of Stirling, Stirling, Scotland, UK.
Alexandra
A
Adams
Novus International, Novus Aqua Research Center, Linh Trung Ward, Thu Duc District, Ho Chi Minh City, Viet Nam.
Ei Lin
EL
Ooi
Institute of Aquaculture, School of Natural Sciences, University of Stirling, Stirling, Scotland, UK.
Darren M
DM
Green
Nong Lam University, Linh Trung Ward, Thu Duc District, Ho Chi Minh City, Viet Nam.
Dang Khoa
DK
Nguyen
Novus International, Novus Aqua Research Center, Linh Trung Ward, Thu Duc District, Ho Chi Minh City, Viet Nam.
Craig L
CL
Browdy
Marine Scotland, Marine Laboratory, Aberdeen, Scotland, UK.
Bertrand
B
Collet
Institute of Aquaculture, School of Natural Sciences, University of Stirling, Stirling, Scotland, UK; Moredun Research Institute, Pentlands Science Park, Bush Loan, Penicuik, Near Edinburgh, Scotland, UK.
Kim D
KD
Thompson
D000276:Adjuvants, Immunologic / Q000008:administration & dosage / Q000494:pharmacology*; D000821:Animal Feed / Q000032:analysis; D000818:Animals; D002397:Catfishes; D004032:Diet / Q000662:veterinary; D019587:Dietary Supplements / Q000032:analysis; D020610:Edwardsiella ictaluri / Q000502:physiology; D004756:Enterobacteriaceae Infections / Q000276:immunology / Q000382:microbiology / Q000662:veterinary*; D005393:Fish Diseases / Q000276:immunology* / Q000382:microbiology; D007113:Immunity, Innate / Q000187:drug effects*; D047071:beta-Glucans / Q000008:administration & dosage / Q000494:pharmacology*
D000276:Adjuvants, Immunologic; D047071:beta-Glucans
Disease resistance; Edwardsiella ictaluri; Immune response; Pangasianodon hypophthalmus; β-glucan