Figure 2. Rooted maximum-likelihood trees illustrating the epidemiologic linkage between sequences from mother (green) and infant (blue) subjects within each transmission pair.

The nucleotide sequences of env V1-V5 region from each pair were aligned with two unrelated outgroup HIV-1 subtype C sequences obtained from the Los Alamos HIV Sequence Database. The branch containing unrelated outgroup sequences are not shown for space considerations. Only bootstrap support values greater than 75 are shown for the major nodes segregating mother and infant subjects.