Skip to main content
. Author manuscript; available in PMC: 2017 Jun 16.
Published in final edited form as: Cell. 2016 Jun 16;165(7):1609–1620. doi: 10.1016/j.cell.2016.04.050

Figure 6. Hinge length and flexibility requirements for the enhanced neutralization activity of the 3BNC117/PGT135 biNAb.

Figure 6

(A) Side and (B) top view of 3BNC117 (cyan; PDB ID: 4JPV) and PGT135 (red; PDB ID: 4JM2) Fabs bound to the Env trimer (PDB ID: 4NCO). The crystal structures of PGT135 and 3BNC117 Fab complexed with gp120 (JRFL and 93TH057, respectively) were aligned onto the crystal structure of the BG505.SOSIP.664 trimer (PDB ID: 4NCO). The distance between the ends of the two Fabs was calculated to be 67Å, suggesting that the IgG3C- hinge variant might facilitate bivalent, intra-trimeric interactions of the 3BNC117/PGT135 biNAb. (C–D) In vitro neutralization activity (IC50 titers (μg/ml)) of 3BNC117 + PGT135 bNAb mix or 3BNC117/PGT135 biNAb expressed with the following hinge domain structures: IgG1, IgG3 and IgG3C- (see also related Fig. 3A for sequence). 3BNC117/PGT135 IgG3C- biNAb exhibited significantly improved neutralization activity (**p<0.001) compared to IgG1 or IgG3 biNAb hinge variants. IC50 titer (μg/ml) results are presented as geometric mean±95%CI. (E–F) IC50 and IC80 titers (μg/ml) of 3BNC117/PGT135 IgG3C- biNAbs with variable hinge domain length. Shorter variants of IgG3C- (“Full length”) were generated by deleting either one (“-15mer”) or two (“-2x15mer”) of the three 15-mer repeats (EPKSSDTPPPSPRSP). (F) Comparison of the neutralization activity between 3BNC117/PGT135 IgG3C- biNAb (full length) and shortened hinge domain variants revealed that enhanced neutralization activity is correlated with hinge domain length. IC50 titer (μg/ml) results are presented as geometric mean±95%CI. *p<0.05; **p<0.001.