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

• Published in: Journal of general microbiology Vol. 137; no. 8; pp. 1971 - 1979
• Main Authors: Cisar, John O, Barsumian, Edward L, Siraganian, Reuben P, Clark, William B, Yeung, Maria K, Hsu, S. Dana, Curl, Shelly H, Vatter, Albert E, Sandberg, Ann L
• Format: Journal Article
• Language: English
• Published: England Soc General Microbiol 01.08.1991
• Subjects: Actinomyces viscosus; Actinomyces viscosus - immunology; Actinomyces viscosus - metabolism; Agglutination Tests; Antibodies, Monoclonal - metabolism; Bacterial Adhesion - physiology; Bacterial Proteins - immunology; Bacterial Proteins - metabolism; Binding Sites - physiology; Durapatite; Electrophoresis, Polyacrylamide Gel; Fimbriae, Bacterial - chemistry; Fimbriae, Bacterial - immunology; Fimbriae, Bacterial - metabolism; Hydroxyapatites - metabolism; Immunoglobulin Fab Fragments - metabolism; Immunoglobulin G - metabolism; Microscopy, Electron; Saliva - metabolism
• ISSN: 0022-1287
• DOI: 10.1099/00221287-137-8-1971

Laboratory of Microbial Ecology Laboratory of Immunology, National Institute of Dental Research, Bethesda, MD 20892, USA Department of Oral Biology, University of Florida, Gainesville, FL 32610, USA Webb-Waring Lung Institute, University of Colorado Medical Center, Denver, CO 80262, USA ABSTRACT Each of five monoclonal antibodies (mAbs) prepared against the type 1 fimbriae of Actinomyces viscosus 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. viscosus whole cells. Maximum values for the number of antibody molecules bound per bacterial cell ranged from 7 x 10 3 to 1.2 x 10 4 for the different 125 I-labelled mAbs and was approximately 7 x 10 4 for 125 I-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. viscosus T14V to saliva-treated hydroxyapatite, each rabbit antibody gave 50% inhibition of adherence when approximately 5 x 10 4 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. viscosus 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. Present address: Department of Pediatric Dentistry. University of Texas Health Science Center at San Antonio, San Aztonio, TX 78284, USA. Present address: Institute for Molecular and Cellular Biology. Osaka University, Osaka, Japan.