The binding of soybean agglutinin (SBA) to the intestinal epithelium of Atlantic salmon, Salmo salar and Rainbow trout, Oncorhynchus mykiss, fed highlevels of soybean meal

A lectin present in soya, soybean agglutinin (SBA), was identified in elect rophoretic profiles and immunoblots of dehulled solvent-extracted soybean m eal (DSSM), full-fat soybean meal (FFSM) and of aqueous extracts of feeds i ncorporating them in their formulation. A quantitative estimation was made of the proportion of SBA comprising the total protein in FFSM and a trial d iet was prepared containing an amount of pure SBA similar to that in diets incorporating high levels of the whole soya product. Fish fed with this die t exhibited similar pathological disruption of the intestinal tract to that observed in fish given a diet with a high level of DSSM (60% of the diet). Furthermore, immuno-histochemistry revealed the binding of the SBA to the enterocytes lining the intestinal villi both of fish fed a diet incorporati ng pure SBA and those fed a diet containing a high-level of soya (60%). Our results suggest that SBA binds in vivo to the intestinal epithelium of fis h and has a contributory role in pathological changes associated with fish feeds containing high levels of soybean proteins. (C) 2001 Elsevier Science BN. All rights reserved.