Fig. 2

CR9501 enhances opening of prefusion F. Two prefusion F variants that include previously described stabilizing mutations and a trimerization motif—a PR-DM or b DS-Cav1—or c a prefusion-stabilized variant lacking the trimerization motif (monomeric DS-Cav1) were immobilized and bound with saturating levels of either motavizumab or CR9501. A second Fab, either CR9501 (black) or motavizumab (red), was then injected over the surface while measuring the binding response. The bottom row shows the controls in which buffer replaced the first Fab incubation. d Model for binding of CR9501 and motavizumab to soluble prefusion F protein illustrating the effects of antibody order-of-addition on trimer opening. The cartoon depicts prefusion F protomers in blue, light gray, and dark gray, CR9501 in pink and light pink, and motavizumab in orange and tan