PEPTIDES (VIDLL18)-V-14 AND (96)FEAAAL(101) DEFINED AS EPITOPES OF ANTIBODIES RAISED AGAINST AMINO-ACID-SEQUENCES OF ENTEROTOXIGENIC ESCHERICHIA-COLI COLONIZATION FACTOR ANTIGEN-I FUSED TO SALMONELLA FLAGELLIN

Antibodies raised against four hybrid Salmonella flagellins carrying a mino acid sequences derived from the fimbrial subunit of the colonizat ion factor I antigen (CFA/I) of enterotoxigenic Escherichia coil (ETEC ), i.e. hybrid flagellins Fla I (aa 1-15), Fla II (aa 11-25), Fla III (aa 32-45) and Fla IV (aa 88-102), were not able to inhibit the in vit ro binding of CFA/I-expressing ETEC bacteria to enterocyte-like Caco-2 cells. However, one of the hybrid flagellins (Fla II) was recognized by a previously described anti-CFA/I subunit mAb (S-CFA/I 17:8) which was able to block adhesion of CFA/I-expressing bacteria to Caco-2 cell s and to bind to the amino acid sequence (15)IDLLQ(19) of the CFA/I fi mbrial subunit. Pepscan analysis of antibodies raised against the hybr id flagellins Fla II and Fla IV showed that they were specific for the sequences (VIDLL18)-V-14 and (96)FEAAAL(101), respectively, of the CF A/I fimbrial subunit. Thus, the discrepancy in the abilities of the an ti-Fla II serum and the mAb S-CFA/I 17:8 to block binding might be asc ribed to their slightly different fine specificity for epitopes.