A specific cell surface antigen of Streptococcus gordonii is associated with bacterial hemagglutination and adhesion to alpha 2-3-linked sialic acid-containing receptors

A Ca2+-independent Lectin activity for alpha 2-3-linked sialic acid-containing receptors is associated with Streptococcus gordonii DL1 (Challis) but not with a spontaneous mutant, strain D102, that specifically Larks hemagglutinating activity, Comparison of crossed-immunoelectrophoresis patterns of parent and mutant sonicated cell extracts identified a unique antigen (Hs antigen) in the parent cell extract that was purified by DEAE Sephacel column chromatography and by a wheat germ agglutinin (WGA) lectin affinity column. The purified antigen formed a single are in crossed immunoelectrophoresis with anti-DL1 serum and migrated as a diffuse band above the 200-kDa marker in sodium dodecyl sulfate-polyacrylamide gel electrophoresis, Immunoelectron microscopy with specific anti-Ils antibody revealed labeling of structures in the fibrillar layer of strain DL1 and no labeling of fibrillar structures on strain D102, Rabbit anti-DL1 serum and anti-Hs Fab inhibited the hemagglutinating activity of strain DL1, and the inhibition was specifically neutralized by purified Hs antigen, Anti-Hs Fab did not inhibit the hemagglutinating activities of several heterologous S. gordonii strains; however, these bacteria were agglutinated by anti-as immunoglobulin G and also by WGA. In contrast, two S. gordonii strains that lacked hemagglutinating activity did not react with anti-as antibody or with WGA, These findings associate the sialic acid-binding lectin activity of S. gordonii DL1 with a specific fibrillar antigen, which is composed of protein and WGA reactive carbohydrate, and indicate that crossreactive antigens occur on other strains of this species that possess hemagglutinating activity.