Conformational inactivation induces immunogenicity of the receptor-binding pocket of a bacterial adhesin.

摘要: Inhibiting antibodies targeting receptor-binding pockets in proteins is a major focus the development of vaccines and antibody-based therapeutic strategies. Here, by using common mannose-specific fimbrial adhesin Escherichia coli, FimH, we demonstrate that locking low-binding conformation induces production binding pocket-specific, adhesion-inhibiting antibodies. A di-sulfide bridge was introduced into conformationally dynamic FimH lectin domain, away from mannose-binding pocket but rendering it defective with regard to mannose binding. Unlike native, functionally active domain potent inducing inhibitory monoclonal blocked FimH-mediated bacterial adhesion epithelial cells urinary bladder infection mice. Inhibition involved direct competition between for pocket. Binding pocket-specific also were abundant polyclonal immune serum raised against domain. The elicited binding-defective protein bound high-affinity more avidly than low-affinity form. However, both soluble blood plasma strongly inhibited antibody recognition We propose binding-pocket epitopes are shielded targeted ligand masking strong immunogenicity unblocked when adhesive nonbinding conformation.