The binding data for each mAb are displayed in Figure S1 and expressed as half-maximal binding concentrations at equilibrium (K 50 ), which approximate to the equilibrium dissociation constants [58] . Of the 58 mAbs, 37 bound to gp120 and 21 to gp41. Several gp120-specific and gp41-specific mAbs showed a broad pattern of reactivity with most recombinant proteins, although usually within a broad range of K 50 values. Overall, there was no relationship between the donor's HIV-1 clade and the clade specificity of the isolated mAbs.