Immunological comparison of major outer membrane proteins from different strains of Escherichia coli.

Rabbits were immunized with either the native trimer or the denatured monomer of OmpF porin of Escherichia coli. The specificity of the two antisera was checked by two different techniques. In liquid immunorecognition assays, the antisera detected the presence of common antigenic determinants at the surface of the monomer and trimer forms. A high response was observed between the two antisera and the native form of OmpF. Although cross-reactivity between the antiserum directed against the OmpF monomer and a denatured form of PhoE was obtained, this denatured porin was weakly recognized by the antiserum specific to the native protein. In immunoblotting experiments, though antiserum directed against the native porin detected the two forms of OmpF, antiserum specific to the monomer recognized only the denatured protein. These two antisera were used to check the immunological relationships of E. coli strains isolated from various contaminated waters. Proteins from several wild strains were compared to the immunoblotting patterns of E. coli reference strains. Porins from the majority of these wild strains were immunorelated to porins of the ML30 strain. In two strains, porins were related to the OmpC/OmpF of the K12 strain, and one strain contained a porin identical to the OmpF of the B strain. Thus, an immunological approach using polyclonal antibodies directed against a major outer membrane protein appears to be fruitful for an accurate classification of various E. coli strains. Moreover, the ecological habitat of a strain can also be investigated by this analysis.