Figure 3

Biophysical and functional characterization of the FLIPr-C1q interaction.

Bio-layer interferometry (BLI) blank subtracted sensograms of (a) C1qA (200-3.1 nM), (b) C1qB (200-3.1 nM) and (c) C1qC (200-12.5 nM) subcomponents tested on covalently immobilized FLIPr. (d) BLI blank subtracted sensograms of FLIPr (5-0.15 μM) on immobilized C1q complex and (e) of C1q complex (3-0.09 nM) on immobilized FLIPr. The amount of ligand associating with the analyte was measured in nanometres (nm). Association and dissociation curves were fitted in a 1:1 model. (f) Summary table of the measured affinity constants (KD). (g) Complement classical pathway influence by FLIPr in WiELISA assay. Relative % of complement activation is shown for each sample. Results are mean of three replicates. P values ≤ 0.05 were considered significant. (h) FLIPr-mediated dose dependent increase of S. aureus survival in whole blood assay. Relative survival was monitored through CFU count. (i) Survival in human blood of S. aureus USA 300 LAC wt, flipR deletion mutant (ΔflipR) and flipR deletion mutant complemented with empty (ΔflipR + pOS1) and with plasmid bearing the flipR insert (ΔflipR + pOS1-flipR). Results are mean of three replicates. P values ≤ 0.05 were considered significant.