Fig. 7.

Contribution of avidity to the neutralizing activity of PG9 and PG16. (a) Neutralization assays were performed as described in Materials and Methods, using IgG or Fab versions of PG9 or PG16. The neutralization data were transformed [x = log(x)] and fitted using a sigmoidal dose-response curve to calculate IC₅₀ neutralization values: MNR = (IC₅₀ Fab)/(IC₅₀ IgG). An MNR value of >1 indicates that a higher molar concentration of Fab is required to achieve 50% neutralization compared to IgG. (b) Neutralization curves of SF162K160N by the IgG and the Fab versions of PG16 from three independent experiments, each conducted in duplicate. The error bars indicate standard deviations.