FIG. 4.

Adsorption of FH and FHL-1 from human plasma. (A) GAS strain 90-226 and its isogenic M1⁻ and Fba⁻ derivatives were incubated with human plasma, harvested by centrifugation, and washed extensively. Bound plasma proteins were eluted and subjected to Western analysis with FH antiserum. The phenotypes of the strains are listed above the blot. Adsorption experiments were performed with plasma or serum from four different sources. The topmost arrow to the right of the figure indicates the 150-kDa FH band. The lower arrow indicates a 49-kDa band determined by N-terminal sequencing to be FH or FHL-1. Lanes: Plasma, loaded with human plasma; FH, loaded with purified FH; M⁺ Fba⁺∗, mock adsorption performed with bacteria in the absence of plasma; None∗∗, mock adsorption performed with plasma in the absence of bacteria. (B) Plasma adsorptions were performed in the presence of protease inhibitors. Plasma adsorptions were performed with wild-type GAS in the absence of protease inhibitors (None) or in the presence of 25 μM E64, 1 mM PMSF, 25 μM E64 and 1 mM PMSF, 25 μM EDTA, or a cocktail of protease inhibitors (PIC; Sigma-Aldrich) as indicated.