FIG. 4.

Humoral immune responses. (A) Envelope-specific binding Ab titers versus rgp120 from HIV-SF162. (B) Neutralizing-Ab titers versus HIV-SF162 in mother-infant pairs. Babies (open symbols) are plotted with respect to their paired mothers (solid symbols) during the course of SHIV infection. The solid vertical line in each graph indicates the birth of the infant. The dotted lines indicate plasma dilutions of 1:50 (A) and 1:4 (B), the assay detection limits. IgG titers of <50 are graphed as 25. NAb titers of <4 are graphed as 2. Median IgG and NAb titers from three independent experiments are shown. Endpt, endpoint.