Enterotoxigenic Escherichia coli isolated from diarrhea stools of chickens were examined for production of heat‐stable enterotoxin II which is considered to be implicated only in diarrhea of pigs. Seven out of 38 strains examined were found to contain heat‐stable enterotoxin II gene, determined by colony hybridization and the polymerase chain reaction. The culture supernatants of these strains caused fluid accumulation in the mouse intestinal loop test. This fluid accumulation activity was not lost by heating at 100°C and was neutralized by anti‐heat‐stable enterotoxin II antiserum. Purified heat‐stable enterotoxin II caused fluid accumulation in the chicken intestinal loop assay. These results indicate that STII‐producing E. coli is implicated in chicken diarrhea.
The heat‐labile enterotoxin (LTc) isolated from chicken enterotoxigenic Escherichia coli was purified to homogeneity and its molecular and antigenic properties were compared with those of purified LTs from porcine and human enterotoxigenic Escherichia coli (LTp, LTh). The A subunit of LTc was identical to that of LTp and the B subunit of LTc was identical to that of LTh but not that of LTp, in mobility on SDS‐polyacrylamide gel electrophoresis. Ouchterlony tests demonstrated that LTc is antigenically identical to LTh but not with LTp. The pI point and amino acid composition of LTc were also compared and the results suggest that chicken enterotoxigenic E. coli produced an LT similar to LTh.
We purified heat‐labile enterotoxins (LThs) from YT3, H‐10407 and YT240 strains isolated from human diarrheal patients. These LThs were immunologically identical to each other. The molecular weights of their A and B subunits were also the same by means of SDS‐polyacrylamide gel electrophoresis. However, the ionic charges of the molecular surfaces of these LThs were different as shown by polyacrylamide gel isoelectric focusing. Though the pI points of B subunits of the LThs were identical to each other, the pI points of A subunits were found to be different. These data suggest that the ionic charge differences among A subunits cause differences in holo LThs in their charge, and that there is heterogeneity among A subunits produced by strains of human enterotoxigenic Escherichia coli.
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