Determination of the cell adhesion specificity of Streptococcus suis with the complete set of monodeoxy analogues of globotriose

Streptococcus suis causes meningitis and other serious infections in pigs a nd humans, and binds to host cell globotriosylceramide. In order to determi ne the essential hydroxyls involved in binding, the complete set of monodeo xy derivatives of the receptor trisaccharide Gal alpha 1-Gal beta 1-4Glc we re tested as inhibitors of bacterial hemagglutination. Removal of the 4 "-, 6 ", 2' or 3'-hydroxyls abolished inhibitory activity, which indicated tha t they were critically involved in binding. The same results were obtained using synthetic lipid-linked monodeoxy derivatives of the trisaccharides in a thin-layer overlay assay. The P-N and P-O subtypes of the S. suis adhesi n showed similar binding patterns. The hydroxyls of the glucose moiety were not critical for binding, although the adhesin binds better to the trisacc haride Gal alpha 1-4Gal beta 1-4Glc than the disaccharide Gal alpha 1-4Gal.