ABSTRACT
GM1 ganglioside has been identified as the receptor for cholera toxin (CT) and heat-labile (LT) enterotoxin of Escherichia coli in many cell types. Using the radial immune hemolysis (RIH) and indirect hemagglutination (IH) tests described for the detection of these enterotoxins, a study was conducted on the 100% inhibition of these reactions by pre-incubating these enterotoxins, a study was conducted on the 100% inhibition of these reactions by pre-incubating these enterotoxins with GM1, GD 1a and GT1 gangliosides. GM1 was found to be much more efficient than the othjer two. With respect to the RIH test, GT1 was more efficient than GD1a as an inhibitor of enterotoxin binding. Similar results were obtained with the IH test. These data also showed that sheep red blood cells provide a good model system for the study of receptors for CT, LT and probably other enterotoxins which bind to gangliosides
Subject(s)
Cholera Toxin , Enterotoxins , Escherichia coli/pathogenicity , Gangliosides/adverse effects , Hemagglutination , HemolysisABSTRACT
A enterotoxina termo-estavel (ST) de E.coli, proveniente de amostra humana, foi parcialmente purificada por cromatografia em coluna de permutador anionico, equilibrado com acetato de amonio 0,01M, pH 9, dialise em sacos tratados com piridina e andrido acetico (V/V) e filtracao em coluna de Sephadex G-15 foi examinado por cromatografia descendente em papel, no sistema de solventes acido acetico, butanol e agua (1:4:5). Conseguiu-se distinguir diversas substancias presentes na amostra e localizar, apos eluicao e analise pelo teste do camundongo recem-nascido, a mancha correspondente a enterotoxina ST. Em recromatografia da toxina ST eluida, no mesmo solvente, obteve-se apenas uma mancha. Entretanto, em vista do baixo rendimento observado neste ultimo metodo, o seu uso deve ser indicado, apenas como um processo analitico da purificacao de ST