FIBRINOGEN BINDING STRUCTURES IN BETA-HEMOLYTIC STREPTOCOCCI GROUP-A, GROUP-C, AND GROUP-G - COMPARISONS WITH RECEPTORS FOR IGG AND AGGREGATED BETA-2-MICROGLOBULIN

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  • 1 January 1979
    • journal article
    • research article
    • Vol. 87  (5) , 303-310
Abstract
Binding of radiolabeled fibrinogen was measured to 197 strains of 16 different bacterial species. All streptococcal strains belonging to groups A, C and G isolated from human sources were strongly positive. S. aureus strains showed low binding values. Occasional group B streptococci were positive. Reactive strains were noted among group C streptococci of animal origin, Streptococcus zooepidemicus and S. equi and bovine .beta.-hemolytic group G streptococci. Bovine .alpha.-hemolytic group G strains and the remaining 7 spp. of human origin were all negative. Inhibition experiments and correlation studies indicated that the streptococcal receptor for fibrinogen was different from immunoglobulin Fc-binding reactivity. Comparisons with the newly discovered .beta.2-microglobulin binding factor showed that trypsin concentrations which destroyed this receptor left the fibrinogen receptor intact. Although the 2 receptors correlate in strain population studies and show competition for binding the difference in trypsin sensitivity indicates that they represent 2 different structural entities. Both receptors might serve as basic markers for M-protein-like surface components of gram-positive cocci.