Cell surface-associated protein implicated in virulence by promoting bacterial attachment to both alpha- and beta-chains of human fibrinogen and inducing the formation of bacterial clumps. Anchored to the cell wall by sortase A (By similarity). The Asp/Ser-rich domain functions as a stalk to allow the ligand binding domain to be displayed in a functional form on the cell surface. Proteolytically cleaved by aureolysin (aur). This cleavage leads to the inactivation of ClfB (By similarity). Belongs to the serine-aspartate repeat-containing protein (SDr) family.