FIG 7.
CD4i MAbs 21c and N12-i15 are sensitive to V1/V2 loop modifications. A binding ELISA was performed to test whether binding by the CD4i MAbs to gp120BaL is affected by the complete truncation of the V1/V2 loops (ΔV1V2) (A) or selective modification of the V1 or V2 loop (B). (A) MAb 21c becomes stringent and MAb N12-i15 loses all binding when the V1/V2 loops are fully truncated. (B) Selective modifications within the V1/V2 loops indicate that the V1 loop is not necessary for binding by MAbs 21c and N12-i15, but the core of the V2 loop (the V2 loop residues which fold into a Greek key conformation) (Fig. 4) is required. Statistically significant differences (P < 0.05) between the “−sCD4” and “+sCD4” columns are marked with an asterisk.