Immunoprotection against enterotoxigenicEscherichia colidiarrhea in rabbits by peroral administration of purified colonization factor antigen I (CFA/I)

Abstract

Development of reliable methods for producing artificially induced immunoprotection against the enterotoxigenic enteropathogens Vibrio cholerae and enterotoxigenic Escherichia coil (ETEC) has been the subject of much investigation [1-6]. Numerous experiments with cholera vibrios, cholera toxin, various cholera toxoids and ETEC heat-labile enterotoxin (LT) as immunogens in various animal species have been reported [25,7,8]. These studies generally lead to the conclusion that immunoprotection against V. cholerae and ETEC diarrhea is primarily dependent upon stimulation of an adequate local immune response in the intestine, the primary mechanism being secretion of specific secretory IgA antibody [2-6,9]. In approaching the problem of immunoprophylaxis against ETEC diarrhea, consideration must be given to the choice of antigens for study. Since numerous different ETEC serotypes produce antigenically identical LT [10,11] this antigen is considered to be a good candidate as an immunogen. On the other hand, since the first step in ETEC infection is intestinal colonization it follows that protection from colonization should be equivalent