Immunochemical and functional studies of Actinomyces viscosus T14V type 1 fimbriae with monoclonal and polyclonal antibodies directed against the fimbrial subunit

Abstract

~~ ~ ~Each of five monoclonal antibodies (mAbs) prepared against the type 1 fimbriae of Actinomyces uiscosus T14V reacted with a 54 kDa cloned protein previously identified as a fimbrial subunit. This purified protein completely inhibited the reaction of a specific anti-type-1-fimbria rabbit antibody with A. uiscosus whole cells. Maximum values for the number of antibody molecules bound per bacterial cell ranged from 7 x lo3 to 1-2 x 104 for the different 251-labelled mAbs and was approximately 7 x lo4 for 251-labelled rabbit IgG or Fab against either type 1 fimbriae or the 54 kDa cloned protein. Although the different mAbs, either individually or as a mixture, failed to inhibit the type-1-fimbria-mediated adherence of A. uiscosus T14V to saliva-treated hydroxyapatite, each rabbit antibody gave 50% inhibition of adherence when approximately 5 x lo4 molecules of IgG were bound per cell. However, binding of each corresponding rabbit Fab had no significant effect on bacterial attachment unless much higher concentrations were used. These findings suggest that antibodies directed solely against the 54 kDa fimbrial subunit do not react with the putative receptor binding sites of A. uiscosus T14V type 1 fimbriae. Instead, inhibition of attachment by the polyclonal antibodies may depend on an indirect effect of antibody binding that prevents the fimbria-receptor interaction.

Dual Function of a Tip Fimbrillin of Actinomyces in Fimbrial Assembly and Receptor Binding

“…This finding is consistent with results from previous studies in which certain antibodies against type 1 fimbriae effectively blocked the attachment of actinomyces to saliva-treated hydroxyapatite (10, 30) while others did not, including those known to be FimP specific (3). In the present study, incubation of Actinomyces with ␣-FimP or ␣-FimQ did not block subsequent aggregation of PRPcoated latex beads (results not shown).…”

Amended Description of the Genes for Synthesis ofActinomyces naeslundiiT14V Type 1 Fimbriae and Associated Adhesin

“…These features raised the possibility that FimQ represented a previously unidentified type 1 fimbria-associated protein. Support for this possibility was gained from proteomic analysis of immunoaffinity-purified type 1 fimbriae, isolated by elution from a coupled FimP-specific monoclonal antibody (MAb) (2). Eluted fimbriae were digested either with pepsin or by dilute-acid hydrolysis, and the resulting peptides were analyzed by liquid chromatography-tandem mass spectrometry.…”

Polypeptides associated with tufts of cell-surface fibrils in an oral Streptococcus

“…Cell-surface hydrophobicity is a factor that has been shown to influence adhesion properties of streptococci, particularly to salivary pellicle (Doyle et al, 1990). Surface hydrophobicities of S. oralis CN3410 and KP34V cells, as measured by the numbers of bacteria adsorbing to hexadecane, were found to be virtually identical (Table 2).…”