FIG 9.

MBL inhibition of NAb binding to IO-NP SOSIP trimers. (A) VRC01-captured B41 SOSIP.v4.1-KG4 IO-NP trimers were exposed to recombinant full-length mouse MBL (5-μg/ml final concentration) before addition of the indicated anti-trimer MAbs at a range of concentrations. (B) The bar chart depicts the percent binding of various anti-trimer MAbs to VRC01-immobilized B41 SOSIP.v4.1-KG4 IO-NP trimers in the presence of full-length recombinant mouse MBL (5-μg/ml final concentration) relative to that with no MBL addition (100% binding). The MAb concentrations were based on earlier titration curves and were intended to generate OD values in the range of 0.7 to 1.0, a signal level that approaches the maximum extent of MAb binding under the assay conditions, and were as follows: BG18, PGT135, SF12, and BG1, 3.3 μg/ml; PGT145, PGT121, 8ANC195, VRC01, 3BNC117, and PG9, 1 μg/ml; and 16D and 2G12, 0.3 μg/ml. Citations describing the MAbs used and their epitopes are located in the Materials and Methods section. The bars are ranked from the highest to the lowest relative binding (in percent) and represent the means from 2 replicate ELISAs + SEM. The red bars indicate that inhibition was >50%. (C) The epitopes for the various MAbs tested in the assay whose results are presented in panel B are plotted on the B41 SOSIP trimer surface. The red patches indicate <50% MAb binding in the presence of MBL at the concentrations tested (see the legend to panel B). (D) As for panel A, except that the B41 SOSIP.v4.1-KG4 IO-NP trimers were exposed to PBS, normal mouse serum (10% by volume, i.e., a 1:10 dilution), or normal mouse IgG (200 μg/ml) before addition of the anti-trimer MAbs.