Differential detection of cholera enterotoxin and Escherichia coli heat-labile enterotoxin by enzyme-linked immunosorbent assays with antibodies specific to the two toxins.

Enzyme-linked immunosorbent assays (ELISAs) with antibodies specific to either cholera enterotoxin (CT) of Vibrio cholerae or heat-labile enterotoxin (LT) of enterotoxigenic Escherichia coli were developed to detect LT and CT, respectively. With these ELISA systems, LT and CT could be detected only with the respective specific antibody. Both antibody ELISA and ganglioside ELISA were used for differential detection of LT and CT, but the former method seemed to be more specific. By this ELISA, as little as 0.1 ng of purified LT or CT could be detected per ml. The type of toxins in fluids in intestinal loops of experimental animals challenged with living cells of either V. cholerae or LT-producing E. coli was identified correctly by this ELISA. These results suggest that the ELISA systems reported here could be used to detect and differentiate CT and LT in unknown samples; it could also be used for assaying toxins in stool specimens for the diagnosis of diarrhea due to V. cholerae or LT-producing E. coli directly, without or before bacterial isolation.