FIG 2 .

Autologous NAb responses of nontransmitting and transmitting mothers. (A) IC₅₀s of nontransmitting and transmitting mothers are color coded by mother. Each square or dot represents the IC₅₀ of an individual envelope variant tested against contemporaneous autologous plasma. Data are shown as raw IC₅₀s on a log₂ scale; black bars represent medians and IQRs, and the dotted line represents an IC₅₀ of 25 (resistant to neutralization at a 1:50 dilution). The P value is based on logistic regression with clustered standard errors using log₂-transformed data. (B) Percentages of virus variants with IC₅₀s below the detection limit, which we defined as the midpoint between 0 and the lowest dilution tested (IC₅₀, 25); IC₅₀s of <100; and IC₅₀s of <200 for nontransmitting (black) and transmitting (gray) mothers. The P values were determined by t tests comparing the proportions of neutralization-resistant viruses of transmitting and nontransmitting mothers at the IC₅₀s shown.