Characterization of a novel bacterial adhesion specificity of Streptococcus suis recognizing blood group P receptor oligosaccharides.

Streptococcus suis causes sepsis, meningitis, and other serious infections in piglets, and meningitis in humans. Hemagglutination inhibition experiments with mono- and oligosaccharides and glycoproteins indicated that galactose-binding strains of S. suis recognized the Gal alpha 1-4Gal sequence present in the P1 and Pk blood group antigen structures. In thin-layer chromatography overlay assays the bacteria bound to trihexosylceramide (GbO3) but not to globoside (GbO4) or Forssman glycolipid (GbO5), in contrast to P-fimbriated Escherichia coli, which bound only to the latter two. The S. suis adhesin also differed from that of E. coli in that some of the hydrogen bonds formed with the receptor, as determined with chemically modified receptor analogues, were different. In agreement with the binding specificity, the S. suis bacteria agglutinated best among P blood group erythrocytes those of the P1k and P2k type, and from different animal erythrocytes those from rabbit, which express GbO3 as the predominant glycolipid. Binding to frozen sections of pig pharyngeal tissue was decreased by the free GbO3 oligosaccharide and its protein conjugate, which indicated that the corresponding glycolipid may function as receptor for galactose-binding strains of S. suis in pig pharyngeal epithelium.