FIG. 1.

Phylogenetic analysis of the V1 to V3 sequences of envelopes investigated. V1 to V3 gp120 Env sequences were used to construct the phylogenetic tree by the neighbor-joining method. The sequence of the NL4.3 virus was used as an outgroup. The percentage of bootstrap repetitions (out of 1,000) in which the nucleotide sequences grouped together is represented as a number at the branch node, but only the bootstrap values of >74% are shown. The genetic distance was 2%. Envelopes from pediatric patients P-1206, P-1114, and P-1031 are designated by the letters S, C, and J, respectively.