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HEALTH IMPACTS : Bt TOXIN4. Vazquez-Padron R.I., L. Moreno-Fierros, L. Neri-Bazan, A.F. Martínez-Gil,G.A. de-la- Riva and R. Lopez-Revilla (2000) : Characterization of the mucosaland systemic immune response induced by Cry1Ac protein from Bacillusthuringiensis HD 73 in mice. Brazilian Journal of Medical and BiologicalResearch, 33, 147-155.The present paper describes important features of the immune response inducedby the Cry1Ac protein from Bacillus thuringiensis in mice. The kinetics of inductionof serum and mucosal antibodies showed an immediate production of anti-Cry1Ac IgM and IgG antibodies in serum after the first immunization with theprotoxin by either the intraperitoneal or intragastric route. The antibody fraction inserum and intestinal fluids consisted mainly of IgG1. In addition, plasma cellsproducing anti-Cry1Ac IgG antibodies in Peyer’s patches were observed usingthe solid-phase enzyme-linked immunospot (ELISPOT). Cry1Ac toxinadministration induced a strong immune response in serum but in the smallintestinal fluids only anti-Cry1Ac IgA antibodies were detected. The data obtainedin the present study confirm that the Cry1Ac protoxin is a potent immunogen ableto induce a specific immune response in the mucosal tissue, which has not beenobserved in response to most other proteins.http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0100-79X20000002000025. Vazquez-Padron, Gonzales-Cabrera, J., García-Tovar, C., Neri-Bazan, L.,Lopez- Revilla, R., Hernandez, M., Moreno-Fierro, L. and de la Riva, G. A.(2000) : Cry1Ac protoxin from Bacillus thuringiensis sp. kurstaki HD73binds to surface proteins in the mouse small intestine. Biochem. Biophys.Res. Comm. 271, 54–58.Bacillus thuringiensis (Bt), considered a safe insecticide, produces insecticidalproteins named Cry during sporulation, which possess exceptional immunologicalproperties. In this work using an immunohistochemical test we demonstratedthat Cry1Ac protoxin (pCry1Ac) binds to the mucosal surface of the mouse smallintestine. Ligand blot assay allowed us to detect, under denaturing conditions,six pCry1Ac-binding polypeptides present in brush border membrane vesiclesisolated from the small intestine. Moreover, this protein induced in situ temporalchanges in the electrophysiological properties of the mouse jejunum. The dataobtained indicate a possible interaction in vivo of Cry proteins with the animalbowel which could induce changes in the physiological status of the intestine.http://www.ncbi.nlm.nih.gov/pubmed/107776806. Vazquez-Padron RI, Moreno-Fierros L, Neri-Bazan L, de la Riva GA, Lopez-Revilla R.Vazquez et al (1999) : Intragastric and intra-peritonealadministration of Cry1Ac protoxin from Bacillus thuringiensis inducessystemic and mucosal antibody responses in mice. Life Sciences, 64(21) : 1897-1912.The spore-forming soil bacterium Bacillus thuringiensis produces parasporalinclusion bodies composed by delta-endotoxins also known as Cry proteins,(37)