Involvement of staphylococcal protein A and cytoskeletal actin in Staphylococcus aureus invasion of cultured human oral epithelial cells

Following the coincidental discovery that beta -actin isolated from renal e pithelial cells was precipitated by staphylococcal protein A (SPA), the pos sibility that SPA and cytoskeletal actin filaments may be involved in Staph ylococcus aureus infection of epithelial cells was considered. Therefore, t o clarify the potential role of SPA and actin filaments in S. aureus infect ion, the invasion efficiency of S. aureus was determined quantitatively by measuring the number of cfu of viable organisms recovered from cultured KB cells. S. aureus invasion was found to be time dependent (0-60 min) and inc reased linearly when increasing numbers of bacteria were added (10(4)-10(6) cfu/ml). However, significant variation in the level of invasion was noted in protein A-deficient S. aureus Wood 46. Cytochalasin B inhibited the inv asion efficiency of S. aureus in a dose-dependent manner. The present study suggests that interaction of staphylococcal protein A and cytoskeletal act in filaments is involved in the S. aureus invasion of cultured KB cells, an d this process may contribute, in part, to the intracellular movement, cell -to-cell spread and dissemination of S. aureus within human oral epithelial cells in vivo.