Fig 2.

Antigenicity of GLA cross-linked gp140. Antibody binding to unmodified (WT) or cross-linked (GLA) gp140 from strain CN54 (clade C) was analyzed by ELISA (A to C) and SPR (D and E). (A) Representative titration series against CN54 gp140 using MAbs covering tested epitopes (indicated in parentheses) show selective decreases of binding of nonneutralizing CD4bs antibody and CD4i antibodies. Curves indicate results of the nonlinear fit. (B and C) The binding index (cross-linked/unmodified) for CN54 gp140 is shown for all antibodies tested, with glycan-dependent antibodies presented in panel C. Values lower than 1.0 indicate loss of binding. Error bars indicate SD from at least five (B) or two (C) independent experiments. (D) The binding index from SPR measurements of CN54 gp140 is shown, with error bars indicating SD of technical repeats. (E) SPR traces are shown for unmodified or cross-linked CN54 gp140 binding to the CD4i MAb 17b. sCD4 was added either before or after cross-linking as indicated. The dotted vertical line indicates the end of the injection. PS, polyclonal serum; *, P < 0.05; ****, P < 0.0001 according to a Kruskal-Wallis test.