Fig. 4

Cross-seeding and in vivo activity. a Concentration-dependent hemolysis of human erythrocytes by selected peptides (average and SD of three replicates) shown as percent of hemolysis compared to 1% Triton. b, c Cytoxicity of P2 (black bars) and P2Pro (gray) to human HeLa cells measured using the CellTiter Blue assay (b) (average and SD of three replicates) and the lactate dehydrogenase (LDH) release assay (average and SD of three replicates), represented as percentage of cell survival compared to control. d Fluorescence micrography of HeLa cells mixed with E. coli O157:H7, treated with FITC-P2 (green channel). Blue is DAPI (4',6-diamidino-2-phenylindole), red is CellMask Deep Red. e Aggregation kinetics of the Alzheimer β (Aβ) peptide at 50 µM with/without P2, monitored using thioflavin-T fluorescence (average and s.d. of three replicates). f Same as b for human islet amyloid polypeptide (IAPP). g Inhibitory effect of 5, 25, and 50 µg/mL P2 on bacterial growth in the presence of human blood serum (25 or 50%; average and SD of three replicates). h ELISA on immobilized FITC-P2 using blood serum of mice treated for 18 days with 30 mg/kg P2. An anti-FITC antibody was used as a positive control for peptide immobilization (three replicates from three mice). i–l Antibacterial efficacy of P2 in a mouse model of bladder infection. The bacterial load of mice infected with E. coli O157:H7 transurethrally was determined after treatment with P2 (P2 administered urethrally (P2 UT) or intraperitoneally (P2 IP)) and controls (ampicillin administered orally (Amp.oral), buffer (mock), and P2Pro administered urethrally (P2Pro2.UT)) in i kidney, j colon, k bladder, and l ureter. Each treatment group consisted of 15 animals. Bacterial loads are expressed as log₁₀(CFU/mL). See text and Methods for more details. Plots i–l show individual measurements, as well as mean and s.d. Significant differences were calculated using ANOVA with Tukey's post hoc test. Statistical significance is indicated as follows: ***P ≤ 0.001