title: Assay method for Vibrio cholerae and Escherichia coli enterotoxins by automated counting of floating chinese hamster ovary cells in culture medium.
abstract: As Chinese hamster ovary (CHO) cells on plastic proliferate, many cells float off into the medium instead of piling up after they form a monolayer. Fewer cells were floating in the medium when CHO cells were incubated with cholera toxin at a concentration as low as 10 pg/ml. The toxin increased the adhesiveness of the cells forming confluent monolayers so that the floating cells accumulated on the adherent monolayers. On the basis of this finding, a simple, quantitative assay method for cholera and Escherichia coli enterotoxins was devised by cultivating CHO cells in a Linbro multidish and counting the cells in the medium with a Coulter Counter. The method was sensitive enough to detect toxins in 100- to 200-fold-diluted culture media of toxigenic E. coli strains. Little or no activity was detected by this method in the culture medium of nontoxigenic E. coli.
mesh_terms: D000818:Animals; D001427:Bacterial Toxins / Q000032:analysis* / Q000494:pharmacology; D001681:Biological Assay / Q000379:methods*; D002448:Cell Adhesion / Q000187:drug effects; D002460:Cell Line; D002478:Cells, Cultured / Q000187:drug effects*; D002772:Cholera Toxin / Q000032:analysis* / Q000494:pharmacology; D006224:Cricetinae; D004768:Enterotoxins / Q000032:analysis* / Q000494:pharmacology; D004926:Escherichia coli / Q000032:analysis*
chemical_list: D001427:Bacterial Toxins; D004768:Enterotoxins; D002772:Cholera Toxin