Localization and enumeration of fimbria-associated adhesins of Bacteroides loescheii.

Monoclonal antibodies that specifically inhibit coaggregation between Bacteroides loescheii PK1295 and its two gram-positive partners Streptococcus sanguis 34 and Actinomyces israelii PK14 were used to enumerate and localize two distinct types of fimbria-associated adhesins on the surface of B. loescheii. Binding studies with radiolabeled monoclonal antibodies indicated that a maximum (Bmax calculated from Scatchard plots) of approximately 400 adhesin molecules specific for S. sanguis and 310 adhesin molecules specific for A. israelii reside on the surface of the cell. Immunoelectron microscopy revealed that the adhesins were not an integral part of the fimbrial subunit; rather, they were usually found on the distal portion of the structures arranged in a random fashion.