The major limitation of the clinical importance of enterotoxigenic E.coli in diarrheal illness is the lack of a simple rapid assay for the enterotoxin produced by certain E.coli. On the basis of the activation of adenylate cyclase by heat labile enterotoxin of E.coli (LT) and by cholera toxin (CT) in intestinal and other tissues, cultured Chinese hamster ovary (CHO) cells with known morphological responses to dibutyryl cyclic adenosine 5' monophosphate (AMP) were exposed to these enterotoxins. Crude culture filtrates of LT producing E.coli and CT stimulated cyclic AMP accumulation and cell elongation in CHO cells. The similarity of time course, concentration dependence, and potentiation by phosphodiesterase inhibitors suggested cyclic AMP mediation of the morphological change. Heat inactivated CT and LT in this system. Choleragenoid inhibited CT; antiserum against CT inhibited both enterotoxin effects. In contrast to culture filtrates of 16 strains of E.coli known to produce LT, culture filtrates from 13 E.coli that do not produce LT did not alter CHO cell morphology. The morphological change is a simple, specific assay for these enterotoxins and detect 3 x 10-17 mol of CT or a 1:250 dilution of crude culture filtrate of LT producing E.coli 334.
ASJC Scopus subject areas
- Infectious Diseases