Blood-group-reactive glycoprotein from human saliva interacts with lipoteichoic acid on the surface of Streptococcus sanguis cells.

[3H]-Glycerol-labelled lipoteichoic acid (LTA) was extracted from Streptococcus sanguis cells using aqueous phenol. Chemical analysis of the LTA yielded phosphate:glycerol:glucose:fatty acids in the mole ratio 1.0:0.97:0.76:0.03. The LTA inhibited the interaction between Strep. sanguis cells and a high mol. wt blood-group-reactive glycoprotein (BGR-glycoprotein) isolated from human saliva and reduced Strep. sanguis-mediated haemagglutination activity. Purified LTA from Strep. mutans strains OMZ61 and HS6, which have been shown not to interact with the BGR-glycoprotein, also inhibited the BGR-glycoprotein mediated aggregation of Strep. sanguis, as did an antiserum prepared against Lactobacillus casei LTA. It is proposed that the binding of the salivary glycoprotein to Strep. sanguis cells in achieved through LTA associated with bacterial surface fibrils.