FIG 1 .
Neighbor-joining trees of maternal HIV envelope genes. Envelope clones from nontransmitting (A) and transmitting (B) mothers. Each envelope sequence is identified by a maternal ID number followed by the timing of isolation and envelope ID. P number, pregnancy week; W number, week after delivery. Samples are color coded on the basis of average IC50s, as shown at the right, when tested against contemporaneous maternal plasma. Viruses resistant to neutralization at a 1:50 dilution of maternal plasma (IC50, 25) are in bold. Reference sequences are not colored.