Streptococcus pyogenes cell wall protein responsible for binding to pharyngeal epithelial cells.

The aim of this study was to identify a streptococcal cell wall substance which is able to bind to epithelial cells. The water-soluble phase of sonicated M+ and M- strains was incubated with pharyngeal and buccal epithelial cells. Electrophoretic analysis of these materials, before and after incubation, showed disappearance of one band from the M+ samples only, after incubation with pharyngeal epithelial cells. The specific anti-M protein serum did not precipitate this protein. Incubation of tested materials with buccal epithelial cells did not change their composition. The molecular mass of this band was estimated as 35,000 Daltons by the use of SDS-PAGE and marker proteins. These results suggest that an adhesin responsible for the streptococcal group A binding to pharyngeal epithelial cells is a protein closely associated with the M antigen.