Analysis of antigenic determinants in cholera enterotoxin and heat-labile enterotoxins from human and porcine enterotoxigenic Escherichia coli.

Antigenic determinants of cholera enterotoxin (CT) and heat-labile enterotoxin from a human strain (LTh) and a porcine strain (LTp) were analyzed by Ouchterlony double-gel diffusion test against anti-CT, anti-LTh, and anti-LTp, which were treated by immunoaffinity column chromatography. The results showed the existence of the following antigenic determinants: (i) antigenic determinants unique to CT, LTh, and LTp, respectively; (ii) an antigenic determinant common to CT, LTh, and LTp; (iii) an antigenic determinant common to CT and LTh, but not LTp; and (iv) an antigenic determinant common to LTh and LTp, but not CT. On the basis of these results, an antigenic scheme for CT, LTh, and LTp is proposed.