Isolation of potent neutralizing antibodies from a survivor of the 2014 Ebola virus outbreak by Zachary A. Bornholdt, Hannah L. Turner, Charles D. Murin, Wen Li, Devin Sok, Colby A. Souders, Ashley E. Piper, Arthur Goff, Joshua D. Shamblin, Suzanne E. Wollen, Thomas R. Sprague, Marnie L. Fusco, Kathleen B. J. Pommert, Lisa A. Cavacini, Heidi L. Smith, Mark Klempner, Keith A. Reimann, Eric Krauland, Tillman U. Gerngross, Dane K. Wittrup, Erica Ollmann Saphire, Dennis R. Burton, Pamela J. Glass, Andrew B. Ward, and Laura M. Walker Science Volume ():aad5788 February 18, 2016 Published by AAAS

Fig. 1 Antigen-binding properties of anti-GP mAbs. Antigen-binding properties of anti-GP mAbs. (A) Apparent binding affinities of GP-specific IgGs to Zaire GP∆TM and Zaire GP∆muc constructs as determined by BLI measurements. Newly discovered anti-GP mAbs are shown as red circles. KZ52 IgG (yellow diamond), 13C6 IgG (green triangle), 1H3 IgG (orange square), and 2G4 IgG (purple hexagon) are included for comparison. (B) Apparent binding affinities of GP-specific IgGs to Zaire sGP and Zaire GP∆muc as determined by BLI measurements. (C) Pie chart summarizing antibody binding profiles. Cross-reactive mAbs refer to those that bind to both GP and sGP. N.B., non-binder; W.B., weak binder. IgG KDs were calculated for mAbs with BLI responses >0.1 nm. MAbs with BLI responses <0.05 nm were designated as N.B.; MAbs with BLI responses between 0.05 and 0.1 nm were designated as W.B. All data are representative of two or more independent experiments. Zachary A. Bornholdt et al. Science 2016;science.aad5788 Published by AAAS

Fig. 2 Epitope mapping. Epitope mapping. (A) Percentage of sGP-reactive and sGP non-reactive mAbs directed against each antigenic site on EBOV GP. Epitope binning was performed using a previously described yeast-based competition assay (20). (B) Percentage of selected KZ52 competitors that cross-react with SUDV GP and BDBV GP. Binding cross-reactivity was assessed by ELISA. (C) ELISA binding of selected KZ52 competitors to a minimal GP core that contains deletions in the mucin-like domain and glycan cap (GPCL). ELISA binding is expressed as the OD405 reading at a concentration of 0.2 μg/ml. (D) Percentage of selected KZ52 non-competitors that cross-react with SUDV GP and BDBV GP. Binding cross-reactivity was assessed by ELISA. (E) Summary of the antigenic sites targeted by the anti-GP mAbs. All data are representative of two or more independent experiments. Zachary A. Bornholdt et al. Science 2016;science.aad5788 Published by AAAS

Fig. 3 Neutralizing activity of anti-GP mAbs. Neutralizing activity of anti-GP mAbs. (A) Percentage of mAbs in each competition group that reached PRNT50 or PRNT80 at concentrations ≤50 μg/ml. The total number of mAbs tested from each competition group are shown at the top of the corresponding bar. (B) PRNT50 and PRNT80 values of selected mAbs from each competition group. KZ52 IgG is included for comparison (green inverted triangle). Red bars indicate median PRNT50 and PRNT80 values. Neutralization assays were performed using a live virus plaque reduction assay. PRNT50 and PRNT80 values represent the concentration of IgG required to reduce viral infectivity by 50 and 80%, respectively. All data are representative of two independent experiments. Zachary A. Bornholdt et al. Science 2016;science.aad5788 Published by AAAS

Fig. 4 Negative stain electron microscopy of Fab:EBOV GP∆TM complexes. Negative stain electron microscopy of Fab:EBOV GP∆TM complexes. (A) A structure-based (PDB 3CSY and 3S88) (5) surface representation of the ebolavirus GP trimer. The mucin domain (gray), glycan cap domain of GP1 (aqua green), GP1 core (blue), GP2 (light blue), fusion loop region of GP2 (pink), and the stalk/HR2 region (orange) have been mapped onto the structure. The residues comprising the trimeric body and the stalk region of the ebolavirus GP are displayed on the right. The mucin domains are modeled only as spheres as they are largely unstructured and poorly defined (27). Residues 613-637 corresponding to the stalk/HR2 region were modeled in silico using threefold symmetry and peptide structure prediction for the HR2 region (28). (B) Corresponding three-dimensional reconstructions of four Fab:EBOV GPΔTM complexes are shown in transparent surface representation (gray) with the model from (A) fitted in the density. Additionally, structural models for each Fab variable region were generated using the ROSIE server (29, 30) and then fitted into the density maps as surface representations. Each structure is shown as side (left) and top (right) views with the exception of ADI-15758, which is shown from the bottom up, respective to the viral membrane. Zachary A. Bornholdt et al. Science 2016;science.aad5788 Published by AAAS

Fig. 5 Therapeutic efficacy of NAbs against MA-EBOV. Therapeutic efficacy of NAbs against MA-EBOV. Kaplan–Meier survival curves for ADI-15974 competitor NAbs (A) KZ52 competitor NAbs (B) 13C6 competitor NAbs (C) and NAbs targeting undefined epitopes (D). Mice were infected with 100 p.f.u. of MA-EBOV and treated intraperitoneally with a single dose of the indicated mAbs at two dpi (dotted black line). Negative control mice were treated with PBS. MAb 2G4 is included for comparison. Data are representative of one experiment with 10 mice per group. Zachary A. Bornholdt et al. Science 2016;science.aad5788 Published by AAAS