DETECTION AND CHARACTERIZATION OF THE COLI SURFACE-ANTIGEN-6 OF ENTEROTOXIGENIC ESCHERICHIA-COLI STRAINS BY USING MONOCLONAL-ANTIBODIES

We describe, for the first time, the production of monoclonal antibodi es (MAbs) against coli surface antigen 6 (CS6) of enterotoxigenic Esch erichia coli (ETEC) and their use for characterization and diagnosis o f CS6, Two MAbs, MAbs CS6-20:11:9 and CS6-2A:14, were produced by immu nizing mice with purified CS6 or CS6-containing bacterial extracts, Th e MAb specificity was demonstrated by enzyme-linked immunosorbent assa y (ELISA), immunoblotting, and immunoelectron microscopy, which showed that the MAbs bound to CS6-expressing bacteria as well as to purified CS6 and CS6 structural subunits but not to CS6-negative bacteria or o ther purified ETEC colonization factors, By using bacterial recombinan ts, i.e., strains with a complete CS6 operon or parts thereof, it was found that both MAbs were specific for CssB, one of the two structural subunits of CS6, Although the MAbs bound specifically to the entire s urface of CS6-expressing bacteria, no structure of CS6 could be identi fied, The usefulness of the MAbs for the detection of CS6 was evaluate d in an inhibition ELISA and in a dot blot test, Ninety-two ETEC strai ns with known colonization factors were analyzed, and all CS6-positive strains were identified by either assay,vith MAb CS6-2A:14, whereas M Ab CS6-20:ll:9 failed to identify two CS6-positive strains; in no inst ance was any CS6-negative strain identified by either of the MAbs, Par allel analyses of 48 strains with a gene probe specific for the other structural subunit of CS6, i.e., CssA, and the MAb-based assays gave i dentical results, suggesting the simultaneous presence of both subunit s.