Invasion of human oral epithelial cells by Prevotella intermedia

Invasion of oral epithelial cells by pathogenic oral bacteria may represent an important virulence factor in the progression of periodontal disease. H ere we report that a clinical isolate of Prevotella intermedia, strain 17, was found to invade a human oral epithelial cell line (KB), whereas P. inte rmedia 27, another clinical isolate, and P. intermedia 25611, the type stra in, were not found to invade the cell line. Invasion was quantified by the recovery of viable bacteria following a standard antibiotic protection assa y and observed by electron microscopy. Cytochalasin D, cycloheximide, monod ansylcadaverine, and low temperature (4 degrees C) inhibited the internaliz ation of P. intermedia 17. Antibodies raised against P. intermedia type C f imbriae and against whole cells inhibited invasion, but the anti-type-C-fim bria antibody inhibited invasion to a greater extent than the anti-whole-ce ll antibody. This work provides evidence that at least one strain of P. int ermedia fan invade an oral epithelial cell line and that the type C fimbria e and a cytoskeletal rearrangement are required far this invasion.