Binding of m43 and control mAbs to recombinant Envs by ELISA (A–E) and to gp41 intermediate structures by Western blot (F).

<p><b>A</b>: Binding of Fab m43 to recombinant gp140s, gp120s and gp41Fc fusion protein. <b>B</b>: Binding of Fabs m43 and Z13, and IgG₁ 2F5 to non-denatured (solid symbols) and denatured gp140_89.6 (empty symbols). <b>C</b>: Binding of Fabs m43, m44 and Z13, and mouse mAb NC-1 to recombinant gp140_89.6 in the absence (solid symbols) or presence (empty symbols) of sCD4 (2 µg/ml). <b>D</b>: Competition of CD4bs mAbs b12, m18 and VRC01, CD4i mAbs m16 and m9Fc fusion protein, and gp41-specific mAbs m44, m46, 2F5 and 4E10 with biotinylated IgG₁ m43 for binding to coated gp140_89.6. <b>E</b>: EC₅₀s of IgG₁ m43, CD4bs mAbs b12 and VRC01, CD4i mAb 17b, and V3 loop-specific mAb 39F with gp120_JRFL wild-type (WT) and V1, V2, V3 loop deletion mutants, and gp120_yu2 WT and its site mutants in CD4bs (D368R), CD4i (I420R), loop D (N279E) and V5 loop (G459E). nd: not done. <b>F</b>: Binding of Fabs m43 and m44 to non-reduced N35_CCG-gp41 (lane 1), N35_CCG-N13 (lane 2), N34_CCG (lane 3), gp41 core (lane 4), and 5HB (25.4 kDa) (lane 5) by Western blot.