RT Journal Article SR Electronic(1) A1 Cisar, John O. A1 Barsumian, Edward L. A1 Siraganian, Reuben P. A1 Clark, William B. A1 Yeung, Maria K. A1 Hsu, S. Dana A1 Curl, Shelly H. A1 Vatter, Albert E. A1 Sandberg, Ann L.YR 1991 T1 Immunochemical and functional studies of Actinomyces viscosus T14V type 1 fimbriae with monoclonal and polyclonal antibodies directed against the fimbrial subunit JF Microbiology, VO 137 IS 8 SP 1971 OP 1979 DO https://doi.org/10.1099/00221287-137-8-1971 PB Microbiology Society, SN 1465-2080, AB 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 × 103 to 1·2 × 104 for the different 125I-labelled mAbs and was approximately 7 × 104 for 125I-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 × 104 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., UL https://www.microbiologyresearch.org/content/journal/micro/10.1099/00221287-137-8-1971