GROUP-B STREPTOCOCCI ADHERE TO A VARIANT OF FIBRONECTIN ATTACHED TO ASOLID-PHASE

Group B streptococci (GBS) are the leading cause of neonatal pneumonia and meningitis, Adherence of GBS to host tissues may play an importan t role in the pathogenesis of infection, The host molecules which medi ate GBS adherence to host tissues are unknown, Many bacterial pathogen s adhere to fibronectin, an important component of the extracellular m atrix (ECM). Some pathogens adhere to both immobilized and soluble fib ronectin, while others adhere to immobilized fibronectin, but not to s oluble fibronectin, Previous data indicated that GBS do not adhere to soluble fibronectin. We studied the ability of GBS to adhere to immobi lized fibronectin. Forty-five per cent of the input inoculum of COH1, a virulent GBS isolate, adhered to fibronectin immobilized on polystyr ene, COH1 did not adhere to the other ECM proteins tested (laminin, ty pe I collagen, vitronectin, and tenascin), Nine out of nine GBS strain s from human sources tested adhered specifically to fibronectin at lev els varying from 4-60%, We considered the possibility that GBS were ad herent to a contaminant in the fibronectin preparation, Properties of fibronectin, including the presence of an immunologic epitope of fibro nectin and binding to collagen, were verified to be properties of the molecule to which GBS adhere, COH1 adhered to fibronectin captured by a monoclonal antibody to fibronectin (FN-15), confirming that the mole cule to which GBS adhere bears immunologic determinants of fibronectin , Adherence of COH1 to fibronectin was inhibited by collagen, confirmi ng that the molecule to which GBS adhere binds to collagen, These data strongly suggest that GBS adhere to fibronectin, and not to a contami nant. Protein blot analysis revealed that GBS were adherent to a high- molecular-weight variant of non-reduced fibronectin monomers and dimer s, GBS did not adhere to reduced fibronectin monomers, We conclude tha t GBS adhere to a variant of plasma fibronectin when attached to a sol id phase.